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921.
922.
O. A. Drozdova S. A. Avilov A. I. Kalinovskii V. A. Stonik Yu. M. Mil'grom Ya. V. Rashkes 《Chemistry of Natural Compounds》1993,29(2):200-205
Four new compounds have been isolated from the fraction of weakly polar triterpene glycosides of the holothurianCucumaria japonica: cucumariosides A1-2 (I), A0-1 (II), A0-2 (III), and A0-3 (IV). The structures of these substances have been established by chemical and physical methods.Deceased.Pacific Ocean Institute of Bioorganic Chemistry, Far-Eastern Scientific Center, Russian Academy of Sciences, Vladivostok. Institute of Chemistry of Plant Substances, Uzbekistan Republic Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 242–248, March–April, 1993. 相似文献
923.
Functional characterization of two-dimensional gel-separated proteins using sequential staining 总被引:4,自引:0,他引:4
Proteins separated by two-dimensional (2-D) gel electrophoresis can be visualized using various protein staining methods. This is followed by downstream procedures, such as image analysis, gel spot cutting, protein digestion, and mass spectrometry (MS), to characterize protein expression profiles within cells, tissues, organisms, or body fluids. Characterizing specific post-translational modifications on proteins using MS of peptide fragments is difficult and labor-intensive. Recently, specific staining methods have been developed and merged into the 2-D gel platform so that not only general protein patterns but also patterns of phosphorylated and glycosylated proteins can be obtained. We used the new Pro-Q Diamond phosphoprotein dye technology for the fluorescent detection of phosphoproteins directly in 2-D gels of mouse leukocyte proteins, and Pro-Q Emerald 488 glycoprotein dye to detect glycoproteins. These two fluorescent stains are compatible with general protein stains, such as SYPRO Ruby stain. We devised a sequential procedure using Pro-Q Diamond (phosphoprotein), followed by Pro-Q Emerald 488 (glycoprotein), followed by SYPRO Ruby stain (general protein stain), and finally silver stain for total protein profile. This multiple staining of the proteins in a single gel provided parallel determination of protein expression and preliminary characterization of post-translational modifications of proteins in individual spots on 2-D gels. Although this method does not provide the same degree of certainty as traditional MS methods of characterizing post-translational modifications, it is much simpler, faster, and does not require sophisticated equipment and expertise in MS. 相似文献
924.
K. V. Shcherbakov Ya. V. Burgart V. I. Saloutin 《Russian Journal of Organic Chemistry》2006,42(12):1838-1844
5,6,7,8-Tetrafluoro-4-hydroxy-2H-chromen-2-one reacts with methylamine to give methylammonium 5,6,7,8-tetrafluoro-2-oxo-2H-chromen-4-olate, regardless of the solvent. The reaction of 3-acetyl-5,6,7,8-tetrafluoro-4-hydroxy-2H-chromen-2-one with the same amine in ethanol or acetonitrile leads to the formation of methylammonium 3-acetyl-5,6,7,8-tetrafluoro-2-oxo-2H-chromen-4-olate, while in dimethyl sulfoxide 5,6,8-trifluoro-7-methylamino-3-(1-methylaminoethylidene)-3,4-dihydro-2H-chromene-2,4-dione is formed. The latter is also formed in the reaction of 5,6,7,8-tetrafluoro-4-hydroxy-3-(1-iminoethyl)-2H-chromen-2-one with methylamine in DMSO, whereas in ethanol and acetonitrile 5,6,7,8-tetrafluoro-3-(1-methylaminoethylidene)-3,4-dihydro-2H-chromene-2,4-dione is obtained. 5,6,7,8-Tetrafluoro-3-(1-methylaminoethylidene)-3,4-dihydro-2H-chromene-2,4-dione reacts with methylamine, yielding 7-mono-or 5,7-bis(methylamino)-substituted derivatives. 相似文献
925.
A. A. Loloiko V. I. Grishkovets A. S. Shashkov V. Ya. Chirva 《Chemistry of Natural Compounds》1988,24(3):320-323
Two triterpene glycosides have been isolated from the leaves ofHedera taurica Carr. (Crimean ivy), family Araliaceae — taurosides B and C, for which, on the basis of the results of chemical and physicochemical methods of investigation the following structures are proposed: 3-0--L-arabinopyranosylhederagenin and 3-0-[0--L-rhamnopyranosyl-(1 2)--L-arabinopyranosyl]oleanolic acid.M. V. Frunze Simferopol' State University. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 379–382, May–June, 1988. 相似文献
926.
提出了利用不同取代基烯类单体的电子亲和势来判断其负离子聚合反应活性的方法.采用密度泛函理论的B3LYP/6-31G(d)方法优化了不同取代基烯类单体几何构型,在B3LYP/6-311++G(3df,2p)水平上计算了其电子亲和势.通过电子亲和势计算值与文献报道实验数据比较,表明本文采用的计算方法是比较可靠的.结合不同取代基烯类单体的电子亲和势的计算结果,通过与Q-e关系及取代基常数σ数据进行比较表明,电子亲和势可以用来判断不同单体负离子聚合反应的活性高低. 相似文献
927.
Time-dependent density-functional theory(TDDFT)has been applied to calculate the electronic structure and second-order nonlinear optical(NLO) properties of some organic molecules.The two-dimensional(2-D)charge transfer charateristics of calculated molecules were studied and compared with corresponding experimental results.All the theoretical results agree well with the measurement.For 2-D molecule with two-fold symmetry,the dominant charge transfer is off-diagonal,while for three-fold symmetry 2-D molecule,the dominant charge transfer is not only between branches and central group but also among branches. 相似文献
928.
929.
Semenov V. V. Cherepennikova N. F. Khorshev S. Ya. Mushtina T. G. Lopatin M. A. Domrachev G. A. 《Russian Journal of Coordination Chemistry》2002,28(12):856-863
1-(3"-Amino)propylsilatrane (I) and 1-(3"-acetamido)propylsilatrane (II) react with anhydrous cobalt(II) chloride to give dichlorobis[1-(3"-amino)propylsilatrane]cobalt(II) {Co[NH2CH2CH2CH2Si(OCH2CH2)3N]2Cl2} (III) and dichlorobis[1-(3"-acetamido)propylsilatrane]cobalt(II) {Co[CH3C(O)NHCH2CH2CH2Si(OCH2CH2)3N]2Cl2} (IV). Being unstable, compound IV transforms into an imidic acid derivative. Reactions of silatranes I and II with dicobalt octacarbonyl afford hexakis[1-(3"-aminoamido)propylsilatrane]cobalt(II) bis(tetracarbonylcobaltate) {Co[NH2CH2CH2CH2Si(OCH2CH2)3N]4.8[HC(O)NHCH2CH2CH2Si(OCH2CH2)3N]1.2}[Co(CO)4]2 (V) and hexakis[1-(3"-acetamido)propylsilatrane]cobalt(II) bis(tetracarbonylcobaltate) {Co[CH3C(O)NHCH2CH2CH2Si(OCH2CH2)3N]6}[Co(CO)4]2 (VI), respectively. In acetonitrile, tetracarbonylcobaltate anions of compound VI are oxidized with atmospheric oxygen and moisture to cobalt hydroxocarbonate, giving a carbonate gel (VII). 相似文献
930.
A.I. Kokorin K.I. Zamaraev V.Ya. Kovner Yu.E. Kirsh V.A. Kabanov 《European Polymer Journal》1975,11(10):719-722
Cu(II) complexes of poly-2-vinylpyridine (P2VP) and poly-2-methyl-5-vinylpyridine (P2M5VP), partially quaternized by dimethylsulphate, and of the analogues (2-methyl-5-ethylpyridine, 2-ethylpyridine) were studied by EPR spectroscopy in a mixture of methanol and water. Peculiarities of the complex formation reaction were observed for the polymers compared to the analogues. At ratios of [Py]:[Cu2+] > 40, the predominant formation of tetrapyridinate-Cu(II) species [(CuL4)]2+ was found for P2M5VP. However, differences were found between the parameters of EPR-spectra for the [CuL4]2+ in the polymer from that of the [Cu(2M5EPy)4]2+. It was suggested that, in the polymer, [CuL4]2+ complexes with structure intermediate between square planar and tetrahedral are formed. Moreover, the maximum value of the pyridine fraction forming [CuL4]2+ in P2M5VP was found to be about 10% and it is appreciably less the value of the fraction in P4VP (about 40%). For P2VP at [Py]:[Cu2+] > 40, an insignificant amount of [CuL1]2+ and [CuL2]2+ are formed in the solution. It follows that the main chain position relative to the ligand nitrogen atom in these polyvinylpyridines affects profoundly the complexation between the macromolecules and Cu(II) ions. The steric hindrances due to the chain are likely to change the [CuL4]2+ structure and to prevent complex formation for P2VP. 相似文献