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1.
Starting from 8-bromoadenosine, 2′,3′-O-isopropylidene-(IIa) and 2′,3′-O-ethoxymethylidene-5′-O-tosyl-8-bromoadenosme (IIb) were synthesized. Compounds IIa, b gave 8,5′-anhydronucleosides (IV a and b) on treatment with hydrogen sulfide in pyridine or aqueous sodium hydrogen sulfide in pyridine at −5–−15°. The structure of IV was confirmed by UV absorption, NMR and elemental analysis. CD and ORD measurements of IV showed large positive Cotton effects around absorption maxima. Acidic removal of the protecting group in IV gave 8,5′-anhydro-8-mercaptoadenosine (V), which was desulfurized to afford 5′-deoxyadesine (VI). 相似文献
2.
8,5'-Aminimino bridging in the guanosine series using 5'- O-tosyl (1) and 5'- O-mesyl derivatives (2) of 2',3'- O-isopropylidene-8-bromoguanosine (5) and hydrazine gave N3,5'-cyclized product 3 and the N5,5'-cyclonucleoside of 4-carboxyhydrazido-5-amino-2-bromoimidazole 4. To exclude the N3,5'-cyclization through ionization in the base moiety, a N2-dimethylaminomethylidene- N1-methoxymethylene derivative 7 was synthesized from 5 through the N2-protected compound 6. 7 was converted into the N2-dimethylaminomethy analogue 8, which with hydrazine yielded first the N2-deprotected form of 8 (9). 8 or 9 with hydrazine under forcing conditions gave an 8,5'-aminimino- N1-methox derivative 10. Oxidation of 10 with sodium metaperiodate or sodium nitrite yielded 8,5'-imino- N1-methoxymethyleneguanosine (11a) and 8,5'-imino- N1-methoxymethylenexanthosine derivative 11b, respectively. 11a was deprotected to 8,5'-imino- N1-methoxymethyleneguanosine 12. 相似文献
3.
The reaction of Ag 2O with pybz (pybz=4-(4-pyridyl)benzoate) gave the monomer compound [Ag(pycz)(H 2O)], 1. Using 4,4′-bipyridyl (bpy) as a spacer to increase the length of the monomer resulted in the nanosized molecular chain compound [Ag 2(pybz) 2(bpy)], 2. In 1, two monomers [Ag(pycz)(H 2O)] are combined together through Agπ, ππ and Ag(CC) interactions to form a dimer, with the distances of 3.34, 3.56 and 3.18 Å, respectively. In 2, the [Ag 2(pybz) 2(bpy)] units are held together via ππ (3.4–3.5 Å) interactions resulting in a 3D network with 1D open channels. 相似文献
4.
Phase behavior of the extraction system, Cyanex 923–heptane/H 2SO 4–H 2O has been studied. The third phase appeared at different aqueous H 2SO 4 concentration with varying initial Cyanex 923 concentration and temperature affects its appearance. Almost all of H 2SO 4 and H 2O are extracted into the middle phase. The H 2SO 4 concentration in the third phase increases with the increasing aqueous acid concentration ( CH2SO4,b) while the water content first increases and then reaches a constant value at CH2SO4,b=11.3 mol l −1. In the region of CH2SO4,b higher than 5.2 mol l −1, the composition of the middle phase is only related to the equilibrium concentration of H 2SO 4 in the bottom phase. H 2SO 4 and H 2O are transferred into the middle phase mainly by their coordination with Cyanex 923 when CH2SO4,b is less than 11.3 mol l −1. When CH2SO4,b is higher than 11.3 mol l −1, excess H 2SO 4 is solubilized into the polar layer of the aggregates. In the region considered, the extracted complex changes from C923 · H 2SO 4 to C923 · H 2SO 4 · H 2O and then to C923 · (H 2SO 4) 2 · H 2O. 相似文献
5.
Structures of the following compounds have been obtained: N-(2-pyridyl)- N′-2-thiomethoxyphenylthiourea, PyTu2SMe, monoclinic, P2 1/ c, a=11.905(3), b=4.7660(8), c=23,532(6) Å, β=95.993(8)°, V=1327.9(5) Å 3 and Z=4; N-2-(3-picolyl)- N′-2-thiomethoxyphenyl-thiourea, 3PicTu2SeMe, monoclinic, C2/ c, a=22.870(5), b=7.564(1), c=16.941(4) Å, β=98.300(6)°, V=2899.9(9) Å 3 and Z=8; N-2-(4-picolyl)- N′-2-thiomethoxyphenylthiourea, 4PicTu2SMe, monoclinic P2 1/ a, a=9.44(5), b=18.18(7), c=8.376(12) Å, β=91.62(5)°, V=1437(1) Å 3 and Z=4; N-2-(5-picolyl)- N′-2-thiomethoxyphenylthiourea, 5PicTu2SMe, monoclinic, C2/ c, a=21.807(2), b=7.5940(9), c=17.500(2) Å, β=93.267(6)°, V=2893.3(5) Å 3 and Z=8; N-2-(6-picolyl)- N′-2-thiomethoxyphenylthiourea, 6PicTu2SMe, monoclinic, P2 1/ c, a=8.499(4), b=7.819(2), c=22.291(8) Å, β=90.73(3)°, V=1481.2(9) Å 3 and Z=4 and N-2-(4,6-lutidyl)- N′-2-thiomethoxyphenyl-thiourea, 4,6LutTu2SMe, monoclinic, P2 1/ c, a=11.621(1), b=9.324(1), c=14.604(1) Å, β=96.378(4)°, V=1572.4(2) Å 3 and Z=4. Comparisons with other N-2-pyridyl- N′-arylthioureas having substituents in the 2-position of the aryl ring are included. 相似文献
6.
The tail-to-tail dimerization of methyl acrylate (MA) in the presence of H 2Ru(PPh 3) 4 (1) or H 2(CO)Ru(PPh 3) 3 (2) and CF 3SO 3H to give a mixture of linear dimers is described. In neat methyl acrylate at 85°C the reaction shows turnover numbers of 300 in 20 h and 640 in 7 d. Mechanistic studies show that the initial step of the reaction is the reduction of H 2Ru(PPh 3) 4 (1) by MA to form Ru(MA) 2 (PPh 3) 2 (5). After activation with CF 3SO 3H the catalytically active species contains only one phosphane ligand. The basic mechanistic features of the dimerization reaction have been revealed by 2H NMR spectroscopy involving the use of CF 3SO 3D. The deuterium-labelling studies indicate the intermediate formation of a ruthenium(II) hydride complex. Subsequent olefin insertions in this complex, followed by β-hydride elimination,lead to the linear dimeric products. 相似文献
7.
The structures of 3,3′-dicarbometoxy-2,2′-bipyridine ( dcmbpy) complexes with copper(II) and silver(I) cations have been determined using single crystal X-ray-diffraction. The crystals of Cu( dcmbpy)Cl 2 are monoclinic, C2/ c, a = 16.966(3), b = 18.373(3), c = 13.154(2) Å, β = 126.543(3)°. The crystals of Ag( dcmbpy)NO 3 · H 2O are also monoclinic, C2/ c, a = 16.7547(13), b = 11.0922(9), c = 18.7789(18) Å, β = 100.228(7)°. The results have been compared with the literature data on the complexes of dcmbpy and its precursors: 2,2′-bipyridine ( bpy) and 3,3′-dicarboxy-2,2′-bipyridine ( dcbpy). Two types of complexes of 3,3′-carboxy derivatives of bpy are distinguished: (1) with metal atom bonded to two N atoms of the same molecule and (2) with metal atom bonded to two N atoms of two different molecules. The Cu( dcmbpy)Cl 2 complex belongs to the first type, whereas Ag( dcmbpy)NO 3 · H 2O belongs to the second type. 相似文献
8.
A novel tetranuclear terbium(III) complex [Tb 4(OH) 4(pybet) 6(H 2O) 8][Tb 4(OH) 4(pybet) 6(H 2O) 7 (NO 3)](ClO 4) 14·6H 2O has been synthesized and shown by X-ray crystallography to have a cubane-like Tb 4(μ 3-OH) 4(μ 2-carboxylato-O,O′) 6 core. The ligand pybet is pyridinoacetate, C 5H 5+N-CH 2CO 2−. Magnetic susceptibility data were measured for this Tb 4 complex in the range of 2.0–320 K and in fields of 1.0 G to 50.0 kG. It is concluded that either there is very weak antiferromagnetic exchange interaction ( J = −0.015 cm −1) or there is a small crystal-field splitting of the 7F 6 Tb III ground state. 相似文献
9.
This work presents chemical modeling of solubilities of metal sulfates in aqueous solutions of sulfuric acid at high temperatures. Calculations were compared with experimental solubility measurements of hematite (Fe 2O 3) in aqueous ternary and quaternary systems of H 2SO 4, MgSO 4 and Al 2(SO 4) 3 at high temperatures. A hybrid model of ion-association and electrolyte non-random two liquid (ENRTL) theory was employed to fit solubility data in three ternary systems H 2SO 4–MgSO 4–H 2O, H 2SO 4–Al 2(SO 4) 3–H 2O at 235–270 °C and H 2SO 4–Fe 2(SO 4) 3–H 2O at 150–270 °C. Employing the Aspen Plus™ property program, the electrolyte NRTL local composition model was used for calculating activity coefficients of the ions Al 3+, Mg 2+ Fe 3+ and SO 42−, HSO 4−, OH −, H 3O +, respectively, as well as molecular species. The solid phases were hydronium alunite (H 3O)Al 3(SO 4) 2(OH) 6, hematite Fe 2O 3 and magnesium sulfate monohydrate (MgSO 4)·H 2O which were employed as constraint precipitation solids in calculating the metal sulfate solubilities. A correlation for the equilibrium constants of the association reactions of complex species versus temperature was implemented. Based on the maximum-likelihood principle, the binary interaction energy parameters for the ionic species as well as the coefficients for equilibrium constants of the reactions were obtained simultaneously using the solubility data of the ternary systems. Following that, the solubilities of metal sulfates in the quaternary systems H 2SO 4–Fe 2(SO 4) 3–MgSO 4–H 2O, H 2SO 4–Fe 2(SO 4) 3–Al 2(SO 4) 3–H 2O at 250 °C and H 2SO 4–Al 2(SO 4) 3–MgSO 4–H 2O at 230–270 °C were predicted. The calculated results were in excellent agreement with the experimental data. 相似文献
10.
By an investigation of the effect of 4,4′-thiobis(2-methyl-6-t.butylphenol) (I) on the decomposition of t.butyl hydroperoxide (TBH) at 85°, analysis of the composition of the reaction mixture and by the determination of the effect of primary transformation products of I on the decomposition of TBH, the mechanism of deactivation of the latter was determined as a model for the reaction of an antioxidant with polymeric hydroperoxide. In the region of an accelerated decomposition of TBH, formation of SO 2, H 2SO 4 and a sulphonic acid was established; the peroxidolytic character was confirmed by carrying out the reaction in presence of calcium carbonate. 相似文献
11.
Reaction of potassium 3{5}-(3′,4′-dimethoxyphenyl)pyrazolide with 2-bromopyridine in diglyme at 130°C for 3 days followed by an aqueous quench, affords 1-{pyrid-2-yl}-3-{3′,4′-dimethoxyphenyl}pyrazole (L 2) in 69% yield after recrystallization from hot hexanes. Complexation of [Cu(NCMe) 4]BF 4 by 2 molar equivalents of 1-{pyrid-2-yl}-3-{2′,5′-dimethoxyphenyl}pyrazole (L 1) or L 2 in MeCN at room temperature, followed by concentration and crystallisation with Et 2O, gives [Cu(L) 2]BF 4 L = L 1, L 2) in good yields. Treatment of AgBF 4 with L 1 or L 2 in MeNO 2 similarly gives [Ag(L) 2]BF 4 L = L 1, L 2); reaction of AfBF 4 with L 2 in MeCN gives a product of stoichiometry [Ag(L 2)(NCMe)]BF 4. The 1H NMR spectra of the [M(L) 2]BF 4 complexes show peaks arising from a single coordinated environment. The single crystal X-ray structure of [Cu(L 1) 2]BF 4 shows a tetrahedral complex cation with Cu---N = 2.011(8), 2.036(8), 2.039(8), 2.110(8) Å. The Cu I centre is close to tetrahedral, the dihedral angle between the least-squares planes formed by the Cu atom and the N donor atoms of the two ligands being 88.3(3)°. Complexation of hydrated Cu(BF 4) 2 by L 2 in MeCN at room temperature yields [Cu(L 2) 2](BF 4) 2. The cyclic voltammograms of the three Ag I complexes in MeCN/0.1 M Bu 4n NPF 6 are suggestive of extensive ligand dissociation in this solvent. 相似文献
12.
139La-NMR chemical shifts were measured for several anionic complexes of formulae Li(C 4H 8O 2) 3/2 [La(ν 3-C 3H 5) 4], [Li(C 4H 8O 2) 2][Cp′ nLa(ν 3-C 3]H 5) 4−n] (Cp′ = Cp(ν 5-C 5H 5); n = 1, 2 and Cp′ = Cp * (ν 5-C 5Me5); N = 1) and Li[R nLa(ν 3-C 3H 4) 4− n] (R = N(SiMe 3) 2; n = 1, 2 and R = CCsIMe 3; n = 4), as well as for neutral compounds for formulae La(ν 3-C 3H 5) 3L n (L = (C 4H 8O 2) 1.5, (HMPT) 2, TMED), Cp′ nLa(ν 3-C 3H 5) 3−n (Cp′= Cp(ν 5-Cp 5H 5), Cp *(ν 5-C 5Me 5); n = 1, 2) and La(ν 3-C 3H 2) 2X(THF) 2 X = Cl, Br, I). Typical ranges of the 139La-NMR chemical shifts were found for the different types of complex independent of number and kind of organyl groups directly bonded to lanthanum. Zusammenfassung139La-NMR-Spektroskopie wurde an einer Reihe anionischer Allyllanthanat(III)-Komplexe der Zusammensetzung
]- [La)ν3-C3H5)4, [Li(C4H8)2][Cp′nLa(ν3-C3H5)4−n(Cp′ = Cp(ν5-C5H5); n = 1, 2 und Cp′ = Cp * (ν5-C5Me5); N = 1) und Li[RnLa(ν3-C3H5)4−n (R = B(SiMe3)2; n = 1, 2 und R = CCSiMe3; n = 4 sowie neutraler Allyllanthan(III)-Komplexe der Zusammensetzung La(ν3-C3H5)3Ln (Ln = (C4H8O2)1.5, (HMPT)2, TMED), Cp′n, La(ν3-C3H5)3−n (Cp′ = Cp(ν5-C5H5), Cp * (ν5- Cp5Me5); n = 1, 2) und La(ν3-Cp3H5)2X(THF)2 (X = Cl, Br, I) durchgefürt. In Abhängikeit von der Anzahl und der Art der am Lanthan gebundenen Gruppen wurden für die verschieden Komplextypen charakteristische Resonanzbereiche ermittelt. 相似文献
13.
Reactions of [(η 6-arene)RuCl 2] 2 (1) (η 6-arene= p-cymene (1a), 1,3,5-Me 3C 6H 3 (1b), 1,2,3-Me 3C 6H 3 (1c) 1,2,3,4-Me 4C 6H 2(1d), 1,2,3,5-Me 4C 6H 2 (1e) and C 6Me 6 (1f)) or [Cp*MCl 2] 2 (M=Rh (2), Ir (3); Cp*=C 5Me 5) with 4-isocyanoazobenzene (RNC) and 4,4′-diisocyanoazobenzene (CN–R–NC) gave mononuclear and dinuclear complexes, [(η 6-arene)Ru(CNC 6H 4N=NC 6H 5)Cl 2] (4a–f), [Cp*M(CNC 6H 4N=NC 6H 5)Cl 2] (5: M=Rh; 6: M=Ir) , [{(η 6-arene)RuCl 2} 2{μ-CNC 6H 4N=NC 6H 4NC}] (8a–f) and [(Cp*MCl 2) 2(μ-CNC 6H 4N=NC 6H 4NC)}] (9: M=Rh; 10: M=Ir) , respectively. It was confirmed by X-ray analyses of 4a and 5 that these complexes have trans-forms for the ---N=N--- moieties. Reaction of [Cp*Rh(dppf)(MeCN)](PF 6) 2 (dppf=1,1′-bis (diphenylphosphino)ferrocene) with 4-isocyanoazobenzene gave [Cp*Rh(dppf)(CNC 6H 4N=NC 6H 5)](PF 6) 2 (7), confirmed by X-ray analysis. Complex 8b reacted with Ag(CF 3SO 3), giving a rectangular tetranuclear complex 11b, [{(η 6-1,3,5-Me 3C 6H 3)Ru(μ-Cl} 4(μ-CNC 6H 4N=NC 6H 4NC) 2](CF 3SO 3) 4 bridged by four Cl atoms and two μ-diisocyanoazobenzene ligands. Photochemical reactions of the ruthenium complexes (4 and 8) led to the decomposition of the complexes, whereas those of 5, 7, 9 and 10 underwent a trans-to- cis isomerization. In the electrochemical reactions the reductive waves about −1.50 V for 4 and −1.44 V for 8 are due to the reduction of azo group, [---N=N---]→[---N=N---] 2−. The irreversible oxidative waves at ca. 0.87 V for the 4 and at ca. 0.85 V for 8 came from the oxidation of Ru(II)→Ru(III). 相似文献
14.
Using zinc hexamethylenedithiocarbamate (Zn(HMDC) 2) and flame atomic absorption spectrometry (FAAS) and/or flow injection hydride generation atomic absorption spectrometry (FI-HGAAS), solvent extraction of As(III) from HCl and H 2SO 4 media into 2,6-dimethyl-4-heptanone (diisobutyl ketone, DIBK) was examined. Arsenic(III) was quantitatively extracted with 2.41×10 −3 mol l −1 Zn(HMDC) 2 from about 0.004 (pH 2.4) to 4 mol l −1 HCl and H 2SO 4 aqueous solutions. The logarithmic conditional extraction constant of As(HMDC) 3 in the HCl–DIBK system was determined to be 8.3±0.7, by the measurement of the distribution ratios of Zn(II) and As(III). The effectiveness of the proposed extraction method was ascertained in the determination of As in geochemical standard reference materials supplied by the Geological Survey of Japan. Furthermore, the analysis of arsenic in procedural blanks was 0.083±0.003 μg l −1. 相似文献
15.
The Schiff base compound, N- N′-bis(4-methoxybenzylidene)ethylenediamine (C 18H 20N 2O 2) has been synthesized and its crystal structure has been investigated by X-ray analysis and PM3 method. The compound crystallizes in monoclinic space group P2 1/ n with a=10.190(1), b=7.954(1), c=10.636(1) Å, β=111.68(1)°, V=801.1(1) Å 3, Z=2 and Dcal=1.229 Mgm −3. The title structure was solved by direct methods and refined to R=0.056 for 2414 reflections [ I>3.0σ( I)] by full-matrix anisotropic least-squares methods. The energy profile of the compound was calculated by PM3 method as a function of θ[N1′–C9′–C9–N1]. The most stable molecular structure of the title compound is the anti conformation, which is different in energy by 5.0 and 1.0 kcal mol −1 from the eclipsed conformation I and gauche conformations, (III and V), respectively. 相似文献
16.
Recent results (post-1990) on the synthesis and structures of bis(trimethylsilyl)methyls M(CHR 2) m (R = SiMe 3) of metals and metalloids M are described, including those of the crystalline lipophilic [Na(μ-CHR 2)] ∞, [Rb(μ-CHR 2)(PMDETA)] 2, K 4(CHR 2) 4(PMDETA) 2, [Mg(CHR 2)(μ-CHR 2)] ∞, P(CHR 2) 2 (gaseous) and P 2(CHR 2) 4, [Yb(CHR 2) 2(OEt 2) 2] and [{Yb(CR 3)(μ-OEt)(OEt 2)} 2]; earlier information on other M(CHR 2) m complexes and some of their adducts is tabulated. Treatment of M(CHR 2) (M = Li or K) with four different nitriles gave the X-ray-characterized azaallyls or β-diketinimates
,
and
(LL′ = N(R)C( tBu)CHR, L′L′ = N(R)C(Ph)C(H)C(Ph)NR, LL″ = N(R)C(Ph)NC(H)C(Ph)CHR, R = SiMe 3 and Ar = C 6H 3Me 2-2,5). The two lithium reagents were convenient sources of other metal azaallyls or β-diketinimates, including those of K, Co(II), Zr(IV), Sn(IV), Yb(II), Hf(IV) and U(VI)/U(III). Complexes having one or more of the bulky ligands [LL′] −, [L′L′] −, [LL] −, [LL″] −, [L″L] −, [LL] − and [{N(R)C( tBu)CH} 2C 6H 4-2] 2− are described and characterized (LL = N(H)C(Ph)C(H)C(Ph)NH, L″L = N(R)C( tBu)C(H)C(Ph)NR, LL = N(R)C( tBu)CHPh). Among the features of interest are (i) the contrasting tetrahedral or square-planar geometry for
and
, respectively, and (ii) olefin-polymerization catalytic activity of some of the zirconium(IV) chlorides. 相似文献
17.
A photoluminescent supramolecular compound [Cd(Hbic) 2(H 2O)]·(4,4′-bpy)·H 2O, H 2bic = 1-H-benzimidazole-5-carboxylic acid, has been synthesized and structurally characterized. With CH–π stacking and hydrogen bond, the 4,4′-bipyridine is used as template to construct the neighboring layers into a three-dimensional supramolecular architecture. Solid-state emission spectrum of compound 1 shows luminescence with emission peak at 565 nm. 相似文献
18.
A series of chromium(III) complexes [Cr(bipy)(HC 2O 4) 2]Cl·3H 2O (1), [Cr(phen)(HC 2O 4) 2]Cl·3H 2O (2), [Cr(phen) 2(C 2O 4)]ClO 4 (3), [Cr 2(bipy) 4(C 2O 4)](SO 4)·(bipy) 0.5·H 2O (4) and [Mn(phen) 2(H 2O) 2] 2[Cr(phen)(C 2O 4) 2] 3ClO 4·14H 2O (5) were synthesized (bipy=4,4′-bipyridine, phen=1,10-phenanthroline), while the crystal structures of 1 and 3–5 have been determined by X-ray analysis. 1 and 3 are mononuclear complexes, 4 contains binuclear chromium(III) ions and 5 is a 3D supromolecule formed by complicated hydrogen bonding. 1–3 are potential molecular bricks of chromium(III) building blocks for synthesis heterometallic complexes. When we use these molecular bricks as ligands to react with other metal salts, unexpected complexes 4 and 5 are isolated in water solution. The synthesis conditions and reaction results are also discussed. 相似文献
19.
The compounds (π-C 5H 5)(CO) 2LM-X (L = CO, PR 3; M = Mo, W; X = BF 4, PF 6, AsF 6, SbF 6) react with H 2S, p-MeC 6H 4SH, Ph 2S and Ph 2SO(L′) to give ionic complexes [(π-C 5H 5)(CO) 2LML′] + X −. Also sulfur-bridged complexes, [(π-C 5H 5)(CO) 3W---SH---W(CO) 3(π-C 5H 5)] + AsF 6− and [(π-C 5H 5)(CO) 3M-μ-S 2C=NCH 2Ph-M(CO) 3(π-C 5H 5)], have been obtained. Reactions with SO 2 and CS 2 have been examined. 相似文献
20.
Three new aminodiphosphonates, namely M(phen)(AEDPH 3) 2·4H 2O (M = Zn, (1); Ni, (2)) and Cu(phen)(AEDPH 3) 2·H 2O (4), in addition to the previously reported Co(phen)(AEDPH 3) 2·4H 2O (3), Cu(2,2′-bipy)(H 2O)(HEDPH 2)·2H 2O (5), and Cu(phen)(H 2O)(HEDPH 2)·2H 2O (6) (AEDPH 4 = 1-aminoethylidenediphosphonic acid, HEDPH 4 = 1-hydroxyethylidenediphosphonic acid, phen = 1,10-phenanthroline and 2,2′-bipy = 2,2′-bipyridyl), have been synthesized and characterized. These compounds are all synthesized at the similar condition (80 °C), whereas they illustrate different frameworks. Compounds 1, 2 and 3 are isomorphous, which contain two same chelate and one six-coordinated metal ion, and display a three-dimensional (3D) supramolecular structure through hydrogen bonds and π–π stacking interactions. Compound 4 contains a chelate and a monodentate , while the Cu ion is five-coordinated. The coordination model of Cu 2+ in 4 is similar to that of 5 and 6. Comparing with four aminoethylidenediphosphonates, the difference of their structures is directed to the coordination model of the metal ions, while the three copper(II) diphosphonates illustrate different structures based on the deprotonized degree of the corresponding diphosphonic acids. 相似文献
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