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991.
The Raman spectroscopic data in the range 500-1800 cm−1 for a series of 15 rare earth double-deckers with tervalent rare earths MIII[Pc(MeOPhO)8]2 (M = Y, La, …, Lu, except Ce, Pr and Pm), reduced state HPr[Pc(MeOPhO)8]2 and intermediate-valent cerium Ce[Pc(MeOPhO)8]2 have been collected using laser excitation source emitting at 632.8 nm. With excitation at 632.8 nm, which is in close resonance with the main Q absorption band of the phthalocyanine ligand, typical Raman marker bands of the monoanion radical [Pc(MeOPhO)8]− were observed at 1500-1528 cm−1 as very strong bands resulting from the coupling of pyrrole CC and aza CN stretchings. For Ce[Pc(MeOPhO)8]2 and HPr[Pc(MeOPhO)8]2, a very strong band at 1499 cm−1 with contributions from both pyrrole CC and aza CN stretchings and also isoindole stretching was the marker Raman band of [Pc(MeOPhO)8]2−. In addition, the influence of ionic radius of the rare earth metal and substituent species on the Raman scatting characteristics of sandwich-type compounds has also been tentatively studied. 相似文献
992.
Two novel coordination polymers, [Zn(dpc)(bmix)0.5]n ( 1 ), [Pb(dpc)(bmix)0.5]n ( 2 ), [dpc = dipicolinate, bmix = 1,4‐bis(2‐methylimidazole‐1‐ylmethyl)benzene], were hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, TGA, and X‐ray single crystal diffraction. In both complexes, the dipicolinate and bmix ligands act as spacers to link metal ions to give a 2D corrugated (6,3) network of 1 and a 3D microporous framework of 2 , respectively. The difference in the architectures is due to a diverging coordination mode of the carboxylate function. Furthermore, solid state fluorescence properties of the two complexes were investigated at room temperature. 相似文献
993.
In this paper, the interaction between herbacetin and BSA was investigated by fluorescence and three-dimensional fluorescence spectroscopy under simulated physiological conditions. It was proved that the fluorescence quenching of BSA by herbacetin was mainly the result of the formation of a herbacetin–BSA complex. The modified Stern–Volmer quenching constant and the corresponding thermodynamic parameters ΔH 0, ΔG 0 and ΔS 0 were calculated at different temperatures. The results indicated that electrostatic interactions were the predominant intermolecular forces in stabilizing the complex. The distance r=3.23 nm between the donor (BSA) and acceptor (herbacetin) was obtained according to Förster’s nonradioactive energy transfer theory. The synchronous fluorescence and three-dimensional fluorescence spectra results showed that the hydrophobity of amino acid residues increased in the presence of herbacetin. These results revealed that the microenvironment and conformation of BSA changed during the binding reaction. 相似文献
994.
The self‐assembled (SA) molecular monolayers of a 3‐aminopropyltrimethoxysilane (3‐APTS) on a silicon (111) surface, and the effects of ultraviolet (UV) pre‐treatment for substrates on the assembling process have been studied using XPS and atomic force microscopy (AFM). The results show that the SA 3‐APTS molecules are bonded to the substrate surface in a nearly vertical orientation, with a thickness of the monolayer of about 0.8–1.5 nm. The SA molecular monolayers show a substantial degree of disorder in molecular packing, which are believed to result from the interactions of amine tails in the silane molecules used with surface functionalities of the substrates, and the oxygen‐containing species from the ambient. UV irradiation for silicon substrates prior to the self‐assembly reaction can enhance the assembly process and hence, significantly increase the coverage of the monolayer assembled for the substrates. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
995.
Three hydroxamic acid ligands (HL1 = acetohydroxamic acid; HL2 = benzohydroxamic acid; HL3 = N-phenylbenzohydroxamic acid), have been used to synthesize series of mono- or dialkyltin(IV) complexes, which include (i) the carboxyl acid hybrid five-coordinated dialkyltin complexes (C4H9)2SnL1L4 (1), [(CH3)2SnL2L5]·0.5C6H6 (2), (HL4 = acetic acid; HL5 = benzoic acid); (ii) the six-coordinated mono-n-butyltin complexes (C4H9)SnL1·Cl2·H2O (3), (C4H9)SnL2·Cl2·H2O (4), [(C4H9)SnL3·Cl2·H2O]·H2O (5), [(C4H9Sn)2(L3)2·Cl2·(OCH3)2] (6); and (iii) the alkali metal-mingled seven-coordinated mono-n-butyltin complexes [(C4H9Sn)3L2Na]+·Cl−·(CH3CH2)2O (7), [(C4H9Sn)3L2K]+·Cl−·CH2Cl2 (8). All complexes were characterized by elemental analyses, IR, 1H, 13C, 119Sn NMR and X-ray single crystal diffraction. In these complexes, hydroxamic acids present bidentate coordination modes with the carbonyl O atom and the hydroxyl O atom binding to tin center. In complexes 1-6, each tin atom is coordinated by one hydroxamic acid ligand. However, in complexes 7 and 8, tin atom is surrounded by three hydroxamic acid ligands, and all hydroxyl O atoms of the ligands also bind to the alkali metal center (Na or K). This kind of organotin(IV) framework containing one alkali metal is found for the first time. Furthermore, the supramolecular structures of 1, 3, 4 and 6 have been found to consist of 1D linear molecular chains formed by intermolecular N-H···X or C-H···X (X = O, N or Cl) hydrogen bonds. For complex 2, an interesting macrocyclic tetramer has been built by the intermolecular N-H···O hydrogen bonds. Fascinatingly, two unique symmetric dimeric structures are recognized in complexes 7 and 8, which is individually bridged by intermolecular N-H···Cl and N-H···O hydrogen bonds. In addition, for 8, the dimeric cycles have been further connected into a 1D supramolecular chain. 相似文献
996.
Yuling Cui Bing Zhang Bingqian Liu Huafeng Chen Guonan Chen Dianping Tang 《Mikrochimica acta》2011,174(1-2):137-144
We report on a new electrochemical biosensing strategy for the sensitive detection of hydrogen peroxide (H2O2) in foodstuff samples. It is based on a gold electrode modified with layer of graphene patterned with a multilayer made from an organic?Cinorganic hybrid nanomaterial. Initially, a layer of thionine (Th) was assembled on the surface of the graphene nanosheets, and these were then cast on the surface of the electrode for the alternate assembly of gold nanoparticles and horseradish peroxidase. The large surface-to-volume ratio and high conductivity of the nanosheets provides a benign microenvironment for the construction of the biosensor. The use of such a multilayer not only shortens the electron transfer pathway of the active center of the enzyme due to the presence of gold nanoparticles, but also enhances the electrocatalytic efficiency of the biosensor toward the reduction of H2O2. The electrochemical characteristics of the biosensor were studied by cyclic voltammetry and chronoamperometry. The number of layers, the operating potential, and the pH of the supporting electrolyte were optimized. Linear response is obtained for the range from 0.5???M to 1.8?mM of H2O2, the detection limit is 10 nM (at S/N?=?3), and 95% of the steady-state current is reached within 2?s. The method was applied to sense H2O2 in spiked sterilized milk and correlated excellently with the permanganate titration method.
A new electrochemical biosensing strategy for sensitive detection of hydrogen peroxide in foodstuff was developed by using a gold electrode modified with a layer of graphene nanosheets patterned with a multilayer made from an organic?Cinorganic hybrid nanomaterial. 相似文献
997.
Pengfei Xiao Changli Bao Naizhong Song Cui Li Qiong Jia 《Russian Journal of Inorganic Chemistry》2011,56(7):1157-1161
In the present study, sec-nonylphenoxy acetic acid (CA100) and its mixtures with four neutral organophosphorus extractants, tri-butyl-phosphate (TBP),
2-ethylhexyl phosphonic acid di-2-ethyl ester (DEHEHP), Cyanex923, and Cyanex925 have been applied to the extraction of rare
earths. Results show that all the four mixing systems do not have evident synergistic effects on the extraction of rare earths.
The different extraction effects have been considered to the separation of rare earths. The four mixtures may be applied to
the separation of yttrium from some certain lanthanoids at proper mole fractions of CA100. 相似文献
998.
A series of novel spindle-like terphenyl-type chromophores, based on 2,5-diphenyl-1,4-distyrylbenzene π-conjugating bridge, N,N-dimethyl and triphenyl amino donors, and Tricyanovinyldihydrofuran(TCF), 1,3,3-trimethyl-5-dicyanovinyl-1-cyclohexene (TDC) acceptors, have been synthesized successfully for the first time. And the non-linear optical properties were evaluated by using the finite-field (FF) method. The results show that, the first-order hyperpolarizability of the chromophores increase with the increase of the withdraw ability of the substituent group on the π-conjugating bridge. 相似文献
999.
1000.