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101.
Speciation of inorganic arsenic by electrochemical hydride generation atomic absorption spectrometry 总被引:11,自引:0,他引:11
A simple procedure was developed for the speciation of inorganic arsenic by electrochemical hydride generation atomic absorption spectrometry (EcHG–AAS), without pre-reduction of As(V). Glassy carbon was selected as cathode material in the flow cell. An optimum catholyte concentration for simultaneous generation of arsine from As(III) and As(V) was 0.06 mol l−1 H2SO4. Under the optimized conditions, adequate sensitivity and difference in ratio of slopes of the calibration curves for As(III) and As(V) can be achieved at the electrolytic currents of 0.6 and 1 A. The speciation of inorganic arsenic can be performed by controlling the electrolytic currents, and the concentration of As(III) and As(V) in the sample can be calculated according to the equations of absorbance additivity obtained at two selected electrolytic currents. The calibration curves were linear up to 50 ng ml−1 for both As(III) and As(V) at 0.6 and 1 A. The detection limits of the method were 0.2 and 0.5 ng ml−1 for As(III) and As(V) at 0.6 A, respectively. The relative standard deviations were of 2.1% for 20 ng ml−1 As(III) and 2.5% for 20 ng ml−1 As(V). The method was validated by the analysis of human hair certified reference material and successfully applied to speciation of soluble inorganic arsenic in Chinese medicine. 相似文献
102.
Sellmann D Hille A Heinemann FW Moll M Reiher M Hess BA Bauer W 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(17):4214-4224
The reactions of [Ru(N2)(PR3)(‘N2Me2S2’)] [‘N2Me2S2’=1,2‐ethanediamine‐N,N′‐dimethyl‐N,N′‐bis(2‐benzenethiolate)(2?)] [ 1 a (R=iPr), 1 b (R=Cy)] and [μ‐N2{Ru(N2)(PiPr3)(‘N2Me2S2’)}2] ( 1 c ) with H2, NaBH4, and NBu4BH4, intended to reduce the N2 ligands, led to substitution of N2 and formation of the new complexes [Ru(H2)(PR3)(‘N2Me2S2’)] [ 2 a (R=iPr), 2 b (R=Cy)], [Ru(BH3)(PR3)(‘N2Me2S2’)] [ 3 a (R=iPr), 3 b (R=Cy)], and [Ru(H)(PR3)(‘N2Me2S2’)]? [ 4 a (R=iPr), 4 b (R=Cy)]. The BH3 and hydride complexes 3 a , 3 b , 4 a , and 4 b were obtained subsequently by rational synthesis from 1 a or 1 b and BH3?THF or LiBEt3H. The primary step in all reactions probably is the dissociation of N2 from the N2 complexes to give coordinatively unsaturated [Ru(PR3)(‘N2Me2S2’)] fragments that add H2, BH4?, BH3, or H?. All complexes were completely characterized by elemental analysis and common spectroscopic methods. The molecular structures of [Ru(H2)(PR3)(‘N2Me2S2’)] [ 2 a (R=iPr), 2 b (R=Cy)], [Ru(BH3)(PiPr3)(‘N2Me2S2’)] ( 3 a ), [Li(THF)2][Ru(H)(PiPr3)(‘N2Me2S2’)] ([Li(THF)2]‐ 4 a ), and NBu4[Ru(H)(PCy3)(‘N2Me2S2’)] (NBu4‐ 4 b ) were determined by X‐ray crystal structure analysis. Measurements of the NMR relaxation time T1 corroborated the η2 bonding mode of the H2 ligands in 2 a (T1=35 ms) and 2 b (T1=21 ms). The H,D coupling constants of the analogous HD complexes HD‐ 2 a (1J(H,D)=26.0 Hz) and HD‐ 2 b (1J(H,D)=25.9 Hz) enabled calculation of the H? D distances, which agreed with the values found by X‐ray crystal structure analysis ( 2 a : 92 pm (X‐ray) versus 98 pm (calculated), 2 b : 99 versus 98 pm). The BH3 entities in 3 a and 3 b bind to one thiolate donor of the [Ru(PR3)(‘N2Me2S2’)] fragment and through a B‐H‐Ru bond to the Ru center. The hydride complex anions 4 a and 4 b are extremely Brønsted basic and are instantanously protonated to give the η2‐H2 complexes 2 a and 2 b . 相似文献
103.
Navnath S. Gavande 《Tetrahedron》2006,62(17):4201-4204
CaH2 was been found, for the first time, as a mild reducing agent to generate thiophenolate anion from Ph2S2 in N-methyl-2-pyrrolidone (NMP) for deprotection of aryl alkyl ethers. Excellent chemoselctivity was observed for substrates having chloro and nitro groups without displacement of the chlorine atom and the nitro group. Selective ether cleavage took place in the presence of α,β-unsaturated carbonyl and nitro groups without reduction and conjugate addition (to the α,β-unsaturated carbonyl group). 相似文献
104.
Investigation of the LaI2/H2 System: Phase Relations and Stacking Disorder Heating of LaI2 under 1 bar hydrogen pressure to 650 °C leads to light gray LaI2H0.95(3), accompanied by a structural change from tetragonal to hexagonal. Sharp reflections in the XRD pattern can be indexed in P63/mmc with a = 4.2158(7)Å and c = 15.508(3)Å, however, diffuse reflections indicate the presence of stacking faults in the structure, which correspond to a polytypic intergrowth of MoS2 and NbS2 type structural fragments. Increasing the reaction temperature to 730 °C results in a better defined diffraction pattern with the peak positions close to those of the 2H‐NbS2 structure type. An X‐ray powder study of the samples LaI2Hn proved the miscibility gap between LaI2 and LaI2Hn (0 ≤ n ≤ 0.5) in agreement with previous results. With decreasing H‐content of the homogeneous phase the lattice parameters change in opposite direction, a increasing to 4.236(1)Å and c decreasing to 15.39(2)Å for the lower limit. 相似文献
105.
Organometallic Lewis Acids. XLII. Carbonyl- and Nitrosyl Complexes of Manganese and Rhenium of Weakly Coordinated Anions (Ph3P)2(ON)2MnX, (Ph3P)n(OC)5–nMX (M = Mn, Re; n = 1, 2; X = FBF3, OSO2CF3, OSO2F, OCORf) The complexes (Ph3P)2(ON)2MnX (X = FBF3, OSO2CF3, OSO2F, OCOCF3, OCOC3F7) and (Ph3P)n(OC)5–nMX (M = Mn, Re; n = 1, 2; X = FBF3, OSO2CF3) have been obtained by reaction of (Ph3P)2(ON)2MnH and (Ph3P)n(OC)5–nMeMe with the corresponding acids HX or from (Ph3P)n(OC)5–nReBr (n = 1, 2) with silver salts AgX, respectively. The compounds have been characterized by their IR and partially by 19F-NMR data. An efficient method for the preparation of the hydride (Ph3P)2(ON)2MnH is reported. 相似文献
106.
Evan M. Benbow 《Journal of solid state chemistry》2006,179(12):3989-3996
Eighteen new intermetallic compounds RMn2TrxZn20−x (2<x<7; R=rare-earth metal; Tr=Al, In) were synthesized using low-melting mixtures of (Tr/Zn) as a solvent. Structural refinement using single-crystal X-ray diffraction data shows that the compounds are substituted variants of the cubic CeCr2Al20-type structure (Fd-3m, Z=8; unit cell parameters vary from a=14.1152(3)Å for YbMn2Al5.3Zn14.7 to a=14.8125(4)Å for SmMn2In5.9Zn14.1). The Zn and Tr elements show site preferences in the indium compounds, but not in the aluminum analogs. The substitution of trielide element for zinc modifies the valence electron count of the compounds to allow for the incorporation of Mn into the structure. Magnetic susceptibility data show no evidence of magnetic ordering down to 3 K. 相似文献
107.
108.
痕量砷流动注射在线还原氢化物发生原子吸收测定 总被引:5,自引:0,他引:5
方法采用流动注射停流技术使水及土壤浸出液中As(V)在线还原为As(Ⅲ),不经手工还原,用氢化物发生原子吸收光谱法直接测定砷的含量。含4mol/L HCl的样品溶液与30%碘化钾溶液在编结式反应器中混合,并在采样环中停流40s,达完全还原后注入到载流中与硼氢化钠反应,采样速度55次/h,检出限(3δ)0.1μg/L,对自来水和土壤浸出液的加标回收结果满意。 相似文献
109.
Four new triphenylgermylruthenium carbonyl compounds HRu(CO)4GePh3, 14; Ru(CO)4(GePh3)2, 15; Ru2(CO)8(GePh3)2, 16; and Ru3(CO)9(GePh3)3(μ-H)3, 17 were obtained from the reaction of Ru(CO)5 with Ph3GeH in hexane solvent at reflux, 68 °C. The major product 14 was formed by loss of CO from the Ru(CO)5 and an oxidative addition of the GeH bond of the Ph3GeH to the metal atom. This six coordinate complex contains one terminal hydrido ligand. Compound 15 is formed from 14 and contains two trans-positioned GePh3 ligands in the six coordinate complex. Compound 16 contains two Ru(CO)4(GePh3) fragments joined by an Ru–Ru single bond. Compound 17 contains a triangular cluster of three ruthenium atoms with three bridging hydrido ligands and one terminal GePh3 ligand on each metal atom. When heated to 125 °C, 14 was converted to the new triruthenium compound Ru3(CO)10(μ-GePh2)2, 18. Compound 18 consists of a triangular tri-ruthenium cluster with two GePh2 ligands bridging two different edges of the cluster and one bridging CO ligand. Ru3(CO)12 was found to react with Ph3GeH at 97 °C to yield three products: 15, and two new compounds Ru3(CO)9(μ-GePh2)3, 19 and Ru2(CO)6(μ-GePh2)2(GePh3)2, 20 were obtained. Compound 19 is similar to 18 having a triangular tri-ruthenium cluster but has three bridging GePh2 ligands, one on each Ru–Ru bond. Compound 20 contains only two ruthenium atoms joined by a single Ru–Ru bond that has two bridging GePh2 ligands and a terminal GePh3 ligand on each metal atom. All compounds were characterized by a combination of IR, 1H NMR, single-crystal X-ray diffraction analyses.
This report is dedicated to Professor Dieter Fenske on the occasion of his 65th birthday for his many pioneering contributions
to the chemistry of metal chalcogenide cluster complexes. 相似文献
110.
《Electroanalysis》2005,17(2):186-190
We report for the first time on the electroassisted biomimetic activation of molecular oxygen by a newly prepared electropolymerized polypyrrole‐manganese phthalocyanine film. The prepared films and their intervention in the electroassisted catalytic reduction of molecular oxygen were analyzed by cyclic voltammetry and UV‐visible spectrophotometry on optically transparent electrodes. The obtained results demonstrate the probable existence of the key‐steps responsible for the suggested formation of the highly reactive manganese oxo intermediate. 相似文献