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1.
2.
We have measured the ionic conductivities of pressed pellets of the layered compounds MUO2PO4 · nH2O, and correlated the results with TGA data. The conductivities (in ohm?1 m?1), at temperatures increasing with decreasing water content over the range 20 to 200°C, were approximately as follows: Li+4H2O, 10?4; Li+, Na+, K+, and NH4+3H2O, 10?4, 10?2, 10?4, and 10?4; H+, Li+, and Na+1.5H2O, 10?2, 10?4, and 10?4; Na+1H2O, 10?5; H+, K+, and NH4+0.5H2O, all 10?5; and H+, Li+, Na+, K+, NH+4, and 12Ca2+OH2O, 10?5, 10?5, 10?4, 10?5, 10?5, and 10?6. A ring mechanism is proposed to account for the high conductivity found in NaUO2PO4 · 3.1H2O. The accurate TGA data showed that most of the hydrates had water vacancies of the Schottky type, and should be represented as MUO2PO4(A ? x)H2O, where x can be between 0 and 0.3.  相似文献   

3.
Probabilities of gamma-ray simultaneous emission have been calculated for the determination of correction factors of full-energy peak areas of radionuclides with a complex decay scheme at measurements of gamma-spectra using HPGe detectors. Coincidence probabilities were determined using the Monte Carlo method for the following radionuclides: 22Na, 24Na, 46Sc, 51Cr, 52Fe, 54Mn, 56Co, 57Co, 58Co, 59Fe, 60Co, 64Cu, 65Zn, 67Cu, 68Ge-68Ga, 75Se, 85Sr, 88Y, 94Nb, 108mAg, 109Cd, 111In, 124Sb, 125Sb, 125I, 131I, 132Cs, 133Ba, 134Cs, 139Ce, 152Eu, 153Sm, 153Gd, 155Eu, 166mHo, 169Yb, 177Lu, 186Re, 207Bi, 208Tl, 212Pb, 212Bi, 241Am.  相似文献   

4.
A recently discovered phenomenon of excessively high X-ray production is discussed. The high yield is attributed to the build-up of potential on non-conducting targets irradiated with accelerated ion beams, and the subsequent discharge. Ion-beams of1H+,1H2 +,2H+,2H2 +,3He+,3He2+,4He+,14N+,14N2+,16O+ and20Ne+ were used. A new mechanism of X-ray excitation is proposed. The increased X-ray fluxes produced by this process are suitable for analytical applications of high specificity. The mechanism of excitation associated with the process, factors affecting the high X-ray yields, applications and a general overview of the studies undertaken with the various ion beams are given.  相似文献   

5.
1,1,1,4,5,5,5-Heptafluoro-4-(trifluoromethyl)-2,3-pentanedione reacted with λ3σ3-phosphorus compounds, PR1R2R3 (R1 = CF3, R2 = R3 = Me, iPr, NEt2; R1 = NCO, R2 = R3 = OMe, OEt, R2−R3 = OCH2CH2O, OCMe2CMe2O; R1 = OSiMe3, R2 = R3 = OEt; R1 = NEt2, R2 = R3 = OCH2CF3; R1 = R2 = Et2N, R3 = OCH2CF3, OCH(CF3)2, OCH2Ph, OC6F5) to give new 1,3,2λ5σ5-dioxaphospholenes. The first λ5σ5 phosphoranes with an OCN group bonded to phosphorus were obtained. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:109–113, 1998  相似文献   

6.
Potential energy curves of 22 electronic states of RhN have been calculated by the complete active space second‐order perturbation theory method. The X1Σ0+ is assigned as the ground state, and the first excited state a3Π0+ is 978 cm?1 higher. The 1Δ(I) and B1Σ+ states are located at 9521 and 13,046 cm?1 above the ground state, respectively. The B1Σ+ state should be the excited state located 12,300 cm?1 above the ground state in the experimental study. Moreover, two excited states, C1Π and b3Σ+, are found 14,963 and 15,082 cm?1 above the X1Σ+ state, respectively. The transition C1Π1–X1Σ0+ may contribute to the experimentally observed bands headed at 15,071 cm?1. There are two excited states, D1Δ and E1Σ+, situate at 20,715 and 23,145 cm?1 above the X1Σ+ state. The visible bands near 20,000 cm?1 could be generated by the electronic transitions D1Δ2–a3Π1 and E1Σ+0–X1Σ+0 because of the spin–orbit coupling effect. © 2013 Wiley Periodicals, Inc.  相似文献   

7.
Sensitive and selective nuclear reaction methods have been sought for the nuclear microprobe measurement of the spatial distributions of13C and13C/12C ratios. The13C(α, n)16O reaction, with neutron detection, is the most selective for13C, and has a sensitivity of ca. 100 ppm. The reactions13C(d, p)14C and12C(d, p)13C, with proton detection, are the most sensitive for the simultaneous measurement of13C and12C, with detection limits of 30 and 2 ppm respectively. Less sensitive alternative reaction pairs are;13C(3He, p)15N and12C(3He, p)14N;13C(d, nγ)14N and12C(d, pγ)13C;13C(3He, pγ)15N and12C(3He, pγ)14N. The conditions governing their use, particularly light element interferences, are detailed.  相似文献   

8.
Diatomic halogens are studied with UV photoelectron spectroscopy using new techniques to preserve high resolution even for reactive species. For the first time vibrational structure is observed on the 2Πu,i (i = 1/2,3/2) states (F2+, Cl2+), the 2Σg+ states (F2+, Cl2+) and the Br2+ (2Πu,32) state. On the 2Πu,i states (F2+, Cl2+, Br2+) spin-orbit splitting is resolved. Indications for a small potential barrier on the F2+ (2Πu,i) state for large internuclear distances are found. A new value for the spin-orbit splitting of the Cl2+(2Πg) state is presented (= ?725 cm?1). The complementary nature of optical emission and photoelectron spectroscopy for small ions is demonstrated leading to a more complete picture of the F2+ (2Πu,i) and Cl2+ (2Πu,i) ionic states.  相似文献   

9.
Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes XXI The Influence of the PR3 Ligands on Formation and Properties of the Phosphinophosphinidene Complexes [{η2tBu2P–P}Pt(PR3)2] and [{η2tBu2P1–P2}Pt(P3R3)(P4R′3)] (R3P)2PtCl2 and C2H4 yield the compounds [{η2‐C2H4}Pt(PR3)2] (PR3 = PMe3, PEt3, PPhEt2, PPh2Et, PPh2Me, PPh2iPr, PPh2tBu and P(p‐Tol)3); which react with tBu2P–P=PMetBu2 to give the phosphinophosphinidene complexes [{η2tBu2P–P}Pt(PMe3)2], [{η2tBu2P–P}Pt(PEt3)2], [{η2tBu2P–P}Pt(PPhEt2)2], [{η2tBu2P–P}Pt(PPh2Et)2], [{η2tBu2P–P}Pt(PPh2Me)2], [{η2tBu2P–P}Pt(PPh2iPr], [{η2tBu2P–P}Pt(PPh2tBu)2] and [{η2tBu2P–P}Pt(P(p‐Tol)3)2]. [{η2tBu2P–P}Pt(PPh3)2] reacts with PMe3 and PEt3 as well as with tBu2PMe, PiPr3 and P(c‐Hex)3 by substituting one PPh3 ligand to give [{η2tBu2P1–P2}Pt(P3Me3)(P4Ph3)], [{η2tBu2P1–P2}Pt(P3Ph3)(P4Me3)], [{η2tBu2P1–P2}Pt(P3Et3)(P4Ph3)], [{η2tBu2P1–P2}Pt(P3MetBu2)(P4Ph3)], [{η2tBu2P1–P2}Pt(P3iPr3)(P4Ph3)] and [{η2tBu2P1–P2}Pt(P3(c‐Hex)3)(P4Ph3)]. With tBu2PMe, [{η2tBu2P–P}Pt(P(p‐Tol)3)2] forms [{η2tBu2P1–P2}Pt(P3MetBu2)(P4(p‐Tol)3)]. The NMR data of the compounds are given and discussed with respect to the influence of the PR3 ligands.  相似文献   

10.
脯氨酸类衍生物结构独特,鲜有报道利用核磁共振(nuclear magnetic resonance,NMR)技术对氨基酸的手性进行鉴别.利用多种NMR技术:1H NMR、1H-1H同核位移相关谱(1H-1H COSY)、1H-1H质子全相关谱(1H-1H TOCSY)、1H-1H核Overhauser效应谱(1H-1H NOESY)、13C NMR、无畸变的极化转移增强法(DEPT135°)、1H-13C检出1H的异核单量子相干(1H-13C HSQC)和1H-13C检出1H的异核多键相关(1H-13C HMBC),对脯氨酸类N-酰胺衍生物两种构象异构体的1H和13C NMR进行了全归属,确定了室温下在二甲基亚砜(DMSO)中L型和D型的顺反异构体以相同的比例同时存在.  相似文献   

11.
The study focuses on the 2H/H, 13C/12C, 15N/14N, 18O/16O and 34S/32S values of defatted dry matter (DFDM) and on the 2H/H, 13C/12C and 18O/16O values of the fat fraction of meat samples from various lamb types reared in seven Italian regions, following different feeding regimes (forage, concentrate, milk). The 13C/12C (r = 0.922), 2H/H (r = 0.577) and 18O/16O (r = 0.449) values of fat and DFDM are significantly correlated, the fat values being significantly lower for C and H and higher for O than for DFDM values and the differences between the two fractions not being constant for different lamb types. The feeding regime significantly affected the 13C/12C, 15N/14N, 18O/16O and 2H/H of fat. The DFDM 2H/H, and 18O/16O values, excluding an outlier, are significantly correlated with the corresponding values in meteoric waters, thus allowing us to trace the variability of geoclimatic factors. 15N/14N is influenced by pedoclimatic conditions, whereas 34S/32S is influenced by the sea spray effect and the surface geology of the provenance area. By applying stepwise linear discriminant analysis only the 2H/H of fat was found not to be significant and 97.7% of the samples were correctly assigned to the lamb type and more than 90% cross‐validated. With the feeding regime, 97.7% of the samples were both correctly assigned and cross‐validated using a predictive model including 13C/12C, 15N/14N, 18O/16O, 34S/32S of DFDM and 18O/16O of fat. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

12.
The CASPT2 potential energy curves (PECs) for O‐loss dissociation from the X2Π, A2Π, B2Σ+, C2Σ+, 14Σ?, 12Σ?, and 14Π states of the OCS+ ion were calculated. The PEC calculations indicate that X2Π, 14Σ?, 12Σ?, and 14Π correlate with CS+(X2Σ+) + O(3Pg); A2Π and B2Σ+ correlate with CS+(A2Π) + O(3Pg); and C2Σ+ probably correlates with CS+(X2Σ+) + O(1Dg). The CASSCF minimum energy crossing point (MECP) calculations were performed for the C2Σ+/14Σ?, C2Σ+/14Π, A2Π/14Σ?, A2Π/12Σ?, A2Π/14Π, and B2Σ+/12Σ? state pairs and the spin‐obit couplings were calculated at the located MECPs. A conical intersection point between the B2Σ+ and C2Σ+ potential energy surfaces was found at the CASSCF level. Based on our calculations, seven O‐loss predissociation processes of the C2Σ+ state are suggested and an appearance potential value of 7.13 eV for the CS+ + O product group is predicted. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011  相似文献   

13.
In the wavelength range of 231-275 nm, we have studied the mass-resolved dissociation spectra of OCS+ via B2+←X23/2(000) and B2+←X21/2(000, 001) transitions by preparing OCS+ ions in the well-defined spin-orbit states. The spectroscopic constants ofυ1(CS stretch)=828.9 (810.4) cm-1, υ2(bend)=491.3 cm-1 and υ3(CO stretch)=1887.2 cm-1 for OCS+(B2+) are deduced. The observed dependence of the υ2(bend) mode excitation of B2+ on the spin-orbit splitting of X2∏(Ω=1/2, 3/2) in the B2+←X2∏ transition can be attributed to the K coupling between the (000)21/2 and (010)2+1/2 vibronic levels of X2∏ state, which makes the B2+(010)←X21/2(000) transition possible.  相似文献   

14.
By using digital deconvolution to improve spectral resolution, earlier NMR studies on 15N-enriched acetamide have been revised and extended to determine the signs of the heteronuclear spin-spin coupling constants. 1J(13CO15N), 2J(13CH315N) and 3J(C1H315N) are negative while 3J(1H13CH3)>0. The results, interpreted on the basis of the ‘selective decoupling’ formalism, were confirmed by computer simulation of the double resonance spectra. It is shown that 2J(1H-α13CO) is significantly larger than 2J(1HN 13CO). Thus, jointly with {1H-β}-13C′ double resonance experiments, {1H-α}-13C′ experiments ought to be most helpful when assigning peptide group carbonyl resonances. The study provides valuable information for the interpretation of heteronuclear coupling constants in polypeptides.  相似文献   

15.
In this study, the titanyl and vanadyl phthalocyanine (Pc) salts (Bu4N+)2[MIVO(Pc4?)]2? (M=Ti, V) and (Bu3MeP+)2[MIVO(Pc4?)]2? (M=Ti, V) with [MIVO(Pc4?)]2? dianions were synthesized and characterized. Reduction of MIVO(Pc2?) carried out with an excess of sodium fluorenone ketyl in the presence of Bu4N+ or Bu3MeP+ is exclusive to the phthalocyanine centers, forming Pc4? species. During reduction, the metal +4 charge did not change, implying that Pc is an non‐innocent ligand. The Pc negative charge increase caused the C?N(pyr) bonds to elongate and the C?N(imine) bonds to alternate, thus increasing the distortion of Pc. Jahn–Teller effects are significant in the [eg(π*)]2 dianion ground state and can additionally distort the Pc macrocycles. Blueshifts of the Soret and Q‐bands were observed in the UV/Vis/NIR when MIVO(Pc2?) was reduced to [MIVO(Pc . 3?)] . ? and [MIVO(Pc4?)]2?. From magnetic measurements, [TiIVO(Pc4?)]2? was found to be diamagnetic and (Bu4N+)2[VIVO(Pc4?)]2? and (Bu3MeP+)2[VIVO(Pc4?)]2? were found to have magnetic moments of 1.72–1.78 μB corresponding to an S=1/2 spin state owing to VIV electron spin. As a result, two latter salts show EPR signals with VIV hyperfine coupling.  相似文献   

16.
Summary Excitation functions were measured by stacked-foil technique for the natZn(p,x)61Cu, 66Zn(p,x)61Cu, 68Zn(p,x)61Cu and natZn(p,x)60Cu nuclear processes up to 100 MeV. The experimental cross sections were compared with published data. On the base of these excitation functions, the cross sections of 64Zn(p,x)61Cu process were also deduced. Integral thick target yields were calculated for the 64Zn(p,x)61Cu and nat,64Zn(p,x)60Cu processes and irradiation parameters were elaborated for the 61Cu production via the 64Zn+p reactions for low and middle energy accelerators. According to our calculations the yield of 61Cu amounts to 1.02 . 1011 Bq . A-1 . s-1 (9.9 mCi A-1 . h-1) from 19®10 MeV while it reaches 3.91 . 1011 Bq . A-1 . s-1 (38 mCi . µ A-1 . h-1) in the energy range of 67®60 MeV.  相似文献   

17.
Reactivities of free radical oxidants, .OH, Br-·2 and Cl3COO. and a reductant, CO-·2, with trypsin and reactive protein components were determined by pulse radiolysis of aqueous solutions at pH 7, 20°C. Highly reactive free radicals, .OH, Br-·2 and CO-·2, react with trypsin at diffusion controlled rates, k(.OH + trypsin) = 8.2 × 1010 M-1 s-1, k(Br-·2 + trypsin) = 2.55 × 109 M-1 s-1 and k(CO-·2 + trypsin) = 2.6 × 109 M-1 s-1. Moderately reactive trichloroperoxy radical, k(Cl3COO. + trypsin) = 3 × 108 M-1 s-1, preferentially oxidizes histidine residues. The efficiency of inactivation of trypsin by free radicals is inversely proportional to their reactivity. The yields of inactivation of trypsin by .OH, Br-·2 and CO-·2 are low, G(inactivation) = 0.6-0.8, which corresponds to ∾ 10% of the initially produced radicals. In contrast, Cl3COO. inactivates trypsin with ∾ 50% efficiency, i.e. G(inactivation) = 3.2.  相似文献   

18.
Summary Extremely low activity levels of cosmic ray induced nuclides have been measured in freshly precipitated rainwater by quick chemical separation coupled with ultra low background gamma-spectrometry. The nuclides detected were 38S (T1/2 = 2.83 h)-38Cl (37.2 m), 39Cl (55.6 m), 24Na (14.96 h), 28Mg (20.9 h), 7Be (53.3 d) and 22Na (2.602 y). The number of atoms in rain water were evaluated to be ranging from 400-1900 l-1 for 39Cl (n = 6, mean: 1200), 30-1500 l-1 for 24Na (n = 16, mean: 520), 80-600 l-1 for 28Mg (n = 13, mean: 260), 1 . 106-4 . 107 l-1 for 7Be (n = 16, mean: 7 . 106) and 2 . 103-1 . 105 l-1 for 22Na (n = 9, mean: 2 . 104). Measurements of activity levels and activity ratios of short-lived cosmic-ray induced short-lived nuclides will open new method to understand atmospheric processes occurred at the altitude of rain cloud.  相似文献   

19.
The cross-sections for the production of the short-lived nuclides:26mAl,197mAu,136mBa,79mBr,139mCe,34Cl,167mEr,114m3In,114m2In,38mK,38mCl,26Na,20F,192Re,207mPb,203mPb,46mSc,183mW,90mZr obtained from (n, 2n), (n, n′), (n, alpha), (n,p) reactions using 14 MeV neutrons, were evaluated by the activation method. The experimental results of this work were compared with those obtained by other authors.  相似文献   

20.
The phase behaviour of the binary systems 4′- n -tetradecyloxy-3′-nitrobiphenyl-4-carboxylic acid (ANBC-14)- n -alkane ( n -tetradecane or n -hexadecane) was investigated by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. The phase behaviour was a function of temperature ( T ) and the effective carbon number of the system ( n*), where n* involves carbon atoms both from the alkoxy group of ANBC-14 and from the n -alkane added. ANBC-14 shows no cubic phase, but the addition of n -alkane induced cubic phases when n*≧c. 15. An interesting point is that the type of cubic phase is Ia 3 d for 15n*≦17, while an Im 3 m type is formed for 18n*≦20. Furthermore, for n* = 22, two types of cubic phase, one with Im 3 m symmetry in the low temperature region and the other with Ia 3 d in the high temperature region, were observed both on heating and cooling. The phase diagram with respect to T and n* is very similar to that of pure one-component ANBC- n , which is a function of T and the number of carbon atoms in the alkoxy group n .  相似文献   

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