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21.
A porphyrin nanotube: size-selective inclusion of tetranuclear molybdenum-oxo clusters 总被引:2,自引:0,他引:2
Harada R Matsuda Y Okawa H Kojima T 《Angewandte Chemie (International ed. in English)》2004,43(14):1825-1828
22.
本文在两次标准加入法[1]的基础上,提出了三组份同时测定的三次标准加入法,并应用于钼、钨和钛的流动注射同时测定。测定条件:[水杨基荧光酮(SAF)]=1.25 ×10-4mol/L,[溴化+六烷基三甲基铵(CTMAB)」=2.5×10-3mol/L,pH1.35,25℃,采样、进样时间分别为10s和18s,进样频率128次/h。为消除组份间协同作用引起的吸光度加合性的偏离,定义了三组份协同系数。将其引入三组份同时测定方法,补偿了吸光度对线性的偏离。补偿后钼、钨和钛的测定范围分别为0.05~0.35,0.25~1.00,0.025~0.30mg/L。测定了钢样及模拟样品中钼、钨和钛含量,结果较好。 相似文献
23.
24.
The electrochemical oxidation of methanol was investigated on a Pt–Ru–Mo catalyst with an in situ infrared reflectance spectroscopy. The electrocatalysts were prepared by an electrochemical deposition and dispersed in a conducting three-dimensional matrix of polyaniline (PAni). We observed that CO2 is produced from methanol oxidation at 350 mV vs. RHE on PAni/Pt–Ru–Mo, which is 100 mV less negative than on PAni/Pt–Ru and 200 mV less than on PAni/Pt. The results suggest that Pt–Ru–Mo is less sensitive to COADS poisoning than Pt–Ru and much more sensitive than Pt. Large differences are observed concerning the average wavenumber of ADS between Pt–Ru–Mo, Pt–Ru, and Pt. 相似文献
25.
Morales D Pérez J Riera L Riera V Miguel D Mosquera ME García-Granda S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(17):4132-4143
Reactions of the complex [MoCl(eta(3)-C(3)H(4)-Me-2)(CO)(2)(phen)] (1) (phen=1,10-phenanthroline) with potassium arylamides were used to synthesize the amido complexes [Mo(N(R)Ar)(eta(3)-C(3)H(4)-Me-2)(CO)(2)(phen)] (R=H, Ar=Ph, 2 a; R=H, Ar=p-tolyl, 2 b; R=Me, Ar=Ph; 2 c). For 2 b the Mo-N(amido) bond length (2.105(4) A) is consistent with it being a single bond, with which the metal attains an 18-electron configuration. The reaction of 2 b with HOTf affords the amino complex [Mo(eta(3)-C(3)H(4)-Me-2)(NH(2)(p-tol))(CO)(2)(phen)]OTf (3-OTf). Treatment of 3-OTf with nBuLi or KN(SiMe(3))(2) regenerates 2 b. The new amido complexes react with CS(2), arylisothiocyanates and maleic anhydride. A single product corresponding to the formal insertion of the electrophile into the Mo-N(amido) bond is obtained in each case. For maleic anhydride, ring opening accompanied the formation of the insertion product. The reaction of 2 b with maleimide affords [Mo(eta(3)-C(3)H(4)-Me-2)[NC(O)CH=CHC(O)](CO)(2)(phen)] (7), which results from simple acid-base metathesis. The reaction of 2 b with (p-tol)NCO affords [[Mo(eta(3)-C(3)H(4)-Me-2)(CO)(2)(phen)](2)(eta(2)-MoO(4))] (8), which corresponds to oxidation of one third of the metal atoms to Mo(VI). Complex 8 was also obtained in the reactions of 2 b with CO(2) or the lactide 3,6-dimethyl-1,4-dioxane-2,5-dione. The structures of the compounds 2 b, 3-OTf, [Mo(eta(3)-C(3)H(4)-Me-2)[SC(S)(N(H)Ph)](CO)(2)(phen)] (4), [Mo(eta(3)-C(3)H(4)-Me-2)[SC(N(p-tol))(NH(p-tol))](CO)(2)(phen)] (5 a), and [Mo(eta(3)-C(3)H(4)-Me-2)[OC(O)CH=CHC(O)(NH(p-tol))](CO)(2)(phen)] (6), 7, and 8 (both the free complex and its N,N'-di(p-tolyl)urea adduct) were determined by X-ray diffraction. 相似文献
26.
Highly sensitive catalytic determination of molybdenum 总被引:1,自引:0,他引:1
A novel, highly sensitive, selective, and simple kinetic method was developed for the determination of Mo(VI) based on its catalytic effect on the oxidation of 1-amino-2-naphthol-4-sulfonic acid (ANSA) with H2O2. The reaction was followed spectrophotometrically by tracing the oxidized product at 465 nm after 30 min of mixing the reagents. The optimum reaction conditions were: 10 mmol l−1 ANSA, 50 mmol l−1 H2O2, 100 mmol l−1 acetate buffer of pH 5.0 ± 0.05 and at 40 °C. Addition of 200 μg ml−1 diethylenetriaminepentaacetic acid (DTPA) conferred high selectivity for the proposed method. Following the recommended procedure, Mo(VI) could be determined with a linear calibration graph up to 2.5 ng ml−1 and a detection limit, based on the 3Sb-criterion, of 0.027 ng ml−1. The unique sensitivity and selectivity of the implemented method allowed its direct application to the determination of Mo(VI) in natural and industrial waste water. The method was validated by comparison with the standard ETAAS method. Moreover, published catalytic-spectrophotometric methods for the determination of molybdenum were reviewed. 相似文献
27.
Contributions to the Chemistry of Transition Metal Alkyl Compounds. 58 On 2-(Dimethylaminomethyl)ferrocenyl Compounds of Vanadium, Molybdenum, Tungsten, Thorium, and Uranium Earlier results according to which dimethylaminomethylferrocenyl groups (FcN) are able to form stable organometallic chelate compounds were confirmed by synthesis of the heterobimetallic chelate compounds (FcN)2VO · Li(acac) II , (FcN)MoO2(acac) III , (FcN)WOCl3 IV , (FcN)Th(acac)3 V , and (FcN)UO2(acac) VI from the corresponding metal acetylacetonates or oxidchlorides and (FcN)Li I . The new compounds were characterized by elemental analysis, the i.r., 1H-n.m.r., and electron spectra and by their effective magnetic moments. 相似文献
28.
A. V. Virovets S. N. Konchenko P. S. Yuferov D. Fenske 《Journal of Structural Chemistry》2004,45(3):496-501
The crystal structures of three cluster compounds: [(µ-H)Fe2Mo(µ3-Te)(CO)8Cp*], [FeMo2(µ3-Te)(CO)7x Cp*2], and [FeMoW(µ3-Te)(CO)7CpCp*], where Cp = 5-C5H5, Cp* = 5-C5 (CH3)5, have been investigated. In the cluster with a tetrahedral {FeMo2Te} core, one can observe positional isomerism of the carbonyl and cyclopentadienyl ligands with respect to the plane through the Fe and Te atoms and the center of the Mo2bond, resulting in two mirror isomers in the racemic crystal. In the cluster with the {FeMoWTe} core, additional chirality causes the formation of four diastereoisomers. Earlier, the structure of the [FeMoW(µ3-Se)(CO)7Cp] cluster with Mo and W atoms coordinated to identical Cp-ligands has been structurally defined. In this crystal, statistical disordering of Mo and W over the metal positions is observed. In the [FeMo(Cp*)W(Cp)(µ3-Te)(CO)7] cluster studied here, the Mo and W atoms are coordinated to different cyclopentadienyl ligands. Due to this, two of four diastereoisomers were isolated as ordered racemic crystals; the other two are nonexistent for steric reasons.Original Russian Text Copyright © 2004 by A. V. Virovets, S. N. Konchenko, P. S. Yuferov, and D. FenskeTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 522–527, May–June 2004. 相似文献
29.
Qiang Xu Prof. Dr. Nobuko Tsumori Prof. Dr. Ling Jiang Masanobu Kondo Ryuichi Arakawa Prof. Dr. 《化学:亚洲杂志》2007,2(5):599-608
Carbonyldinitrosyltris(fluorosulfato)tungstate(II) and ‐molybdate‐(II) anions, [fac‐M(CO)(NO)2(SO3F)3]? (M=W, Mo), which are novel weakly coordinating anions that contain a metal carbonyl/nitrosyl moiety, have been generated in fluorosulfonic acid and completely characterized by multinuclear NMR, IR, and Raman spectroscopy as well as ESI mass spectrometry. ESI MS measurements performed for the first time on a superacidic solution system unambiguously reveal the formation of the monoanionic, mononuclear W and Mo complexes formulated as [M(CO)(NO)2(SO3F)3]? (M=W, Mo). Multinuclear NMR spectroscopic studies at natural abundance and 13C and 15N enrichment clearly indicate the presence of one CO ligand, two equivalent NO ligands, and two types of nonequivalent SO3F? groups in a 2:1 ratio. The IR and Raman spectra reveal that the two equivalent NO ligands have a cis conformation, thus indicating a fac structure. Density functional calculations at the B3LYP level of theory predict that these anions have a singlet ground state (1A′) with a Cs symmetry along with C–O and N–O vibrational frequencies that are in agreement with the experimental observations. Mulliken population analysis shows that the monovalent negative charge is dispersed on the bulky sphere, the surface of which is covered by all the negatively charged O and F atoms with charge densities much lower than SO3F?, suggesting that [fac‐M(CO)(NO)2(SO3F)3]? (M=W, Mo) are weakly nucleophilic and poorly coordinating anions. 相似文献
30.
The structure of [(CF3N2NMe)Mo(CH2SiMe3)2] (in which (CF3N2NMe)2? is [(3‐CF3C6H4NCH2CH2)2NMe]2?) is approximately trigonal bipyramidal with one axial and one equatorial alkyl ligand. Heating of solutions of [(CF3N2NMe)Mo(CH2SiMe3)2] in [D6]benzene in the presence of five equivalents of 2‐butyne led to diamagnetic [(CF3N2NMe)Mo(CHSiMe3)(η2‐MeC?CMe)], whose structure is approximately square pyramidal with the alkyne occupying the axial site. Addition of one equivalent of cyclohexene sulfide to [(CF3N2NMe)Mo(CH2SiMe3)2] at room temperature produced the diamagnetic, dimeric molybdenum(IV) sulfido complex, [{(CF3N2NMe)MoS}2]. This complex is composed of two approximately trigonal bipyramidal centers, each containing one axial and one equatorial sulfur atom. Oxidation of [(CF3N2NMe)Mo(CH2SiMe3)2] with hexachloroethane resulted in formation of tetramethylsilane, HCl, and the sparingly soluble, red alkylidyne complex, [{(CF3N2NMe)Mo(CSiMe3)Cl}2]. This complex forms a dimer through bridging chlorides. The oxidation reactions of [(CF3N2NMe)Mo(CH2SiMe3)2] with 2‐butyne, cyclohexene sulfide, or C2Cl6 are all proposed to proceed by α‐hydrogen abstraction in the MoVI species to yield (initially) the Mo?CHSiMe3 species and tetramethylsilane. 相似文献