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141.
微量稀土对超导稳定化基体铜材的性能和组织的影响 总被引:4,自引:0,他引:4
研究了微量稀土元素对铜的机械性能、导电性和组织的影响,在铜中加入微量钇、钕、镝、铒和富铈混合稀土后,使铜的抗拉强度有所提高,并保持良好的塑性和导电性。 相似文献
142.
Various combinations of Cu(0), CuCl, 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen) were used as catalysts for the grafting polymerizations of styrene from polysiloxane macroinitiators functionalized with benzyl chloride. While Cu(0)/bpy alone promotes the grafting, narrower polydispersities were obtained in the presence of CuCl. Analysis of the Cu(0) surface before and after polymerization by a combination of AFM, TGA and FTIR investigations reveals the formation of bpy or phen films on Cu(0). In the presence of CuCl, the ligand film appears decorated with CuCl particles which increase in size with increasing the CuCl concentration. The initial layer occurs most likely as a result of complexation between the ligands and the Cu(0) surface and acts as a support for the rest of the film. These observations are consistent with the film formation on Cu(0) from related nitrogen donors and indicate that the reactivity of the Cu surface may depend not only on its prior treatment but also on the deposition of ligands from the reaction mixture. 相似文献
143.
《Electroanalysis》2003,15(2):121-125
This work describes the behavior of copper solid amalgam electrodes (CuSAE). The applied potential range has been compared with that of the silver solid amalgam electrode (AgSAE) and the hanging mercury drop electrode (HMDE). In 0.05 M tetraborate buffer the applicable potential range of CuSAE is+0.945 V to ?1.75 V excluding ?0.2 V to ?0.5 V, where the anodic oxidation of copper occurs. CuSAE does not need other than electrochemical pre‐treatment, which has been documented by the evaluated repeatability of eleven voltammetric curves of Cd2+ (0.1 ppm), Pb2+ (0.1 ppm) and Mn2+ (0.5 ppm). The obtained results showed that CuSAE could substitute the solid copper, amalgamed copper or liquid copper amalgam electrodes, and can be applied for the study of systems needing an addition of Cu2+ ions into the measured solution. 相似文献
144.
Four new two-ligand complexes of copper(II) with 2,2′-bipyridine and one of three different α-hydroxycarboxylic acids (lactic, H2LACO; 2-methyllactic, H2MLACO; and mandelic, H2MANO) were prepared. Complexes 1–3 of general formula [Cu(HL)2(bipy)]·nH2O (HL=monodeprotonated acid), were characterized by elemental analysis, IR, electronic and EPR spectroscopy, magnetic measurements and thermogravimetric analysis. Complexes 1 (HL=HLACO, n=2), 2 (HL=HMLACO, n=1) and 3a (the result of attempted recrystallization of 3, of formula [Cu(HMANO)(bipy)2](HMANO)·H2MANO·CH3CN were studied by X-ray diffractometry. The copper atom is in an elongated, tetragonally distorted octahedral environment in 1 and 2 and in 3a has a coordination polyhedron intermediate between a square pyramid and a trigonal bipyramid, as evaluated in terms of the parameter τ. In 1 and 2 the α-hydroxycarboxylato ligand is bidentate and monoanionic but in 3a there are three forms: a monodentate monoanion, a monoanionic counterion, and a neutral molecule. 相似文献
145.
The electrochemical double layer between Cu(111) electrodes and aqueous electrolytes (F− and SO2−4 at various pH values) was studied by means of linear scan voltammetry and ac impedance measurements. It is found that electrochemisorption of oxygen species proceeds on the Cu(111) surface in the potential regions more negative than the electrodissolution potential of copper. The adsorption-desorption kinetics are analysed; the anodic and cathodic symmetry coefficients are found to be equal (α = β = 0.3), and the standard rate constant is k° = 4 × 10−10cm s−1. 相似文献
146.
Copper is a bioessential element in biology with truly unique chemical characteristics in its two relevant oxidation states +I and +II. Significant progress has been made in recent years in the elucidation of the frequently surprising biochemistry of this trace element. Those advances were especially furthered through mutual stimulation involving results from biochemistry, molecular biology, and medicine on one hand and the synthesis as well as the structural and spectroscopic characterization of low molecular weight model complexes on the other. The most notable features of protein-bound active copper are its almost exclusive function in the metabolism of O2 or N/O compounds (NO, N2O) and its frequent association with oxidizing organic and inorganic radicals such as tyrosyl, semiquinones, superoxide, or nitrosyl. This unique biological role of copper can be rationalized given its chemical and assumed evolutionary background. 相似文献
147.
In the absence of any special luminescence reagent, emission of weak chemiluminescence has been observed during the decomposition of hydrogen peroxide catalyzed by copper(II) in basic aqueous solution. The intensity of the chemiluminescence was greatly enhanced by addition of DNA and was strongly dependent on DNA concentration. Based on these phenomena, a flow-injection chemiluminescence method was established for determination of DNA. The chemiluminescence intensity was linear with DNA concentration in the range 2×10–7–1×10–5 g L–1 and the detection limit was 4.1×10–8 g L–1 (S/N=3). The relative standard deviation was less than 3.0% for 4×10–7 g L–1 DNA (n=11). The proposed method was satisfactorily applied for determination of DNA in synthetic samples. The possible mechanism of the CL reaction is discussed. 相似文献
148.
In the presence of CuCN, reaction of γ,γ-dialkoxyallylic zirconium species 1 with imines proceeded at the γ-position of 1 to give gem-dialkoxyhomoallylic amines 3 in high yield. In this reaction, γ,γ-dialkoxyallylic zirconium species 1 acts as an α,β-unsaturated acyl anion equivalent. 相似文献
149.
Matthew HesfordWilliam Levason Simon D. OrchardGillian Reid 《Journal of organometallic chemistry》2002,649(2):214-218
The syntheses and spectroscopic characterisation of the new facultative tridentate tellurium containing ligands MeS(CH2)3Te(CH2)3SMe (S2Te) and H2N(CH2)3Te(CH2)3NH2 are described. The complexes of the former, fac-[Mn(CO)3(S2Te)]CF3SO3, [Rh(Cp*)(S2Te)][PF6]2, [MCl(S2Te)]PF6 (M=Pd or Pt), [Cu(S2Te)]BF4 and [Ag(S2Te)]CF3SO3 have been prepared and characterised by analysis, IR, 1H-, 13C{1H}-, 125Te- and 195Pt-NMR spectroscopy and mass spectrometry. The X-ray crystal structures of [Rh(Cp*)(S2Te)][PF6]2 and [PtCl(S2Te)]PF6 are described. The results are compared with those obtained from complexes of the related tridentates Te{(CH2)3TeR}2, Se{(CH2)3SeMe}2 and S{(CH2)3SR}2. 相似文献
150.
Synthesis and Structure of the First Ternary Lead(II) Copper(I) Oxide: PbCu2O2 PbCu2O2 can be prepared by solid state reaction or by precipitation from a basic aqueous solution. Single crystals of the new compound were prepared by recrystallisation from a molten mixture (PbO? Cu2O) and investigated by X-ray diffractometer technique. PbCu2O2 crystallizes isotypically with the homologue silver compound PbAg2O2 (monoclinic with a = 8.223 Å, b = 8.289 Å, c = 6.015 Å, β = 132.62°, Z = 4, space group C? C 1 2/c 1). The crystallographic data from the X-ray investigation are reported. The structure is built by endless [PbO4/4]- and [CuO2/4]-chains. Pb2+ has a one-sided asymmetric coordination with four next oxygen neighbours and Cu+ forms a stretched dumbbell with two oxygen atoms. 相似文献