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81.
《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(2):420-428
Four novel organotin complexes of two types—[R2Sn(o‐SC6H4CO2)]6 (R=Me, 1 ?H2O; nBu, 2 ) and {[R2Sn(m‐CO2C6H4S)R2Sn(m‐SC6H4CO2)SnR2]O}2 (R=Me, 3 ; nBu, 4 )—have been prepared by treatment of o‐ or m‐mercaptobenzoic acid and the corresponding R2SnCl2 (R=Me, nBu) with sodium ethoxide in ethanol (95 %). All the complexes were characterized by elemental analysis, FT‐IR and NMR (1H, 13C, 119Sn) spectroscopy, TGA, and X‐ray crystallography diffraction analysis. The molecular structure analyses reveal that both 1 and 2 are hexanuclear macrocycles with hydrophobic “pseudo‐cage” structures, while 3 and 4 are hexanuclear macrocycles with double‐cavity structures. Furthermore, the supramolecular structure analyses show that looser and more intriguing supramolecular infrastructures were also found in complexes 1 – 4 , which exist either as one‐dimensional chains of rings or as two‐dimensional networks assembled from the organometallic subunits through intermolecular C? H???S weak hydrogen bonds (WHBs) and π–π interactions. 相似文献
82.
Ping Yang Wei Zhang Yukou Du Xiaomei Wang 《Journal of molecular catalysis. A, Chemical》2006,260(1-2):4-10
Platinum nanoparticle core-polyaryl ether trisacetic acid ammonium chloride dendrimer shell nanocomposites (Pt@Gn-NACl) were prepared and used as catalysts for hydrogenation of nitrobenzenes to anilines with molecular hydrogen under mild conditions. The as-prepared nanoparticles have mean particle size from 2.0 to 5.5 nm, depending on the molar ratio of the metal and the dendrimer. The Pt nanoparticles demonstrate near-monodisperse when the molar ratio of Pt and G3-NACl is below 30. The interaction among three carboxyl groups terminated at the dendron and the metallic core keeps the Pt nanoparticles from agglomerating. The colloidal solution of Pt nanoparticles stabilized by the dendrimer, in which the molar ratio of Pt/G3-NACl was less than 60, is stable without precipitation for several weeks. The dendrons attach to the metal core radially, and a substantial fraction of the surface of the metal nanoparticle is unpassivated and available for catalytic reactions. Turnover frequencies for the hydrogenation of nitrobenzenes to anilines change from 353 to 49 h−1 depending on the dendrimer generation and substrates. The dendrimer catalysts are stable during the catalytic hydrogenation process and can be recovered by centrifugation and reused. The results suggest the effectiveness of polyaryl ether trisacetic acid ammonium chloride dendrimer as a stabilizer for the preparation of Pt nanoparticle catalysts. 相似文献
83.
JIN Xiang-qun ZHANG Jing-min XU Hui ZHOU Yan WANG Guang-shu ZHAO Yan-qiu ZHANG Han-qi 《高等学校化学研究》2006,22(2):185-188
Introduction Malignantdiseasesarecharacterizedbytheunreg ulatedgrowthoftransformedcells.Inrecentyears,dramaticinsightsintothemolecularmechanismsofthis phenomenonhavebeenachievedfrombasiccancerre search.Manycellularfunctionsareregulatedbychan gesingeneexpr… 相似文献
84.
氨基酸柱前衍生化的3种新荧光试剂的光谱特性及高效液相色谱研究 总被引:1,自引:2,他引:1
合成了3种新的荧光标记试剂:吖啶-N-乙酰氯,咔唑-9-乙酰氯和咔唑-9-丙酰氯。它们的最大发射降激发波长分别为430nm,368nm,和365nm。3种衍生化试剂与氨基酸形成的衍生物在pH6.5的条件下结合梯度洗脱程序在C18反相柱上对色谱条件进行了优化。 相似文献
85.
An investigation of electronic structure in some neurotransmitter drugs has been made using the CNDO/2 semi-empirical molecular orbital method.The electronic structure has been conveniently characterized by the electronic parameters nett atomic population (NAP) and bond index (BI). A variation of these electronic parameters with respect to conformation has been studied and has been found unlikely to exceed 0.1 e in most. cases. Further, the useful extent to which the electronic parameters of some commonly occurring functional groups may be regarded as conformationally invariant has been demonstrated. Also presented are (i) a discussion on the intramolecular close-approach of functional groups — the interaction between terminal —COO? and ?NH3+ groups of α-ω anaino acids is explicitly considered; (ii) an enquiry into the extension of ‘standard’ (idealized) geometry models in the elucidation of electronic structure.The implication of the results and observations presented here are briefly discussed with reference to classical and quantum structure-activity studies of drug molecules. 相似文献
86.
A preparative method for 9a-hydroxylation of 91/xxlarge916.gif" alt="Delta" align="BASELINE" BORDER="0">5-391/xxlarge946.gif" alt="beta" align="MIDDLE" BORDER="0">-hydroxysteroids using the fungi ofCircinella sp. 10Kh-1220 not capable of modifying theA ring has been developed. It is established that the yields of the main and the side products greatly depend on the transformation conditions, mycelium age, and the structure of the steroid substrate. Under the optimal transformation conditions novel 991/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-hydroxysubstituted derivatives of androstenolone, pregnenolone, 16-dehydro-1691/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">,1791/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-epoxy-, and-1691/xxlarge945.gif" alt="agr" align="BASELINE" BORDER="0">-methoxypregnenolone have been obtained in 36–80 % yields.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 737–743, April, 1994. 相似文献
87.
Summary There are a number of reagents available for fluorescent labelling of primary amines. These include dansyl chloride, o-phthalaldehyde,
fluorescamine, and a new reagent, 9-fluorenylmethylchloroformate (FMOC), reported recently. This paper describes a reversed-phase
HPLC procedure for the separation and fluorescence detection of polyamines following pre-column derivatization with FMOC.
The polyamines studied by this method include putrescine, cadaverine, spermidine, and spermine. Experiments were carried out
to determine maximum fluorescence excitation and emission wavelengths, optimum reaction pH, linear ranges, and minimum detection
limits for each of the polyamines. The HPLC method includes a gradient program which provides complete separation from serum
hydrolysate components and specificity for the four polyamines with detection limits ranging from 2 to 9 pg. This procedure
was applied to hydrolyzed serum samples. 相似文献
88.
Summary A high-performance liquid chromatographic method, with 9-anthryldiazomethane as derivatizing agent, has been developed for
the simultaneous determination ofN-carbamoyl aspartate andl-dihydroorotate in serum. Sample preparation for 1 mL serum was by simple liquid-liquid extraction and then derivatization.
The compounds were separated on a Luna C18(2) column by use of a gradient prepared from acetonitrile and 10 mM sodium acetate
buffer, pH 6.0, and fluorimetric detection was performed at excitation and emission wavelengths of 365 nm and 412 nm, respectively.
The response was found to be linearly dependent on concentration between 0.8 and 60 956;g mL−1 forl-dihydrooratate and between 0.9 and 90 956;g mL−1 forN-carbamoyl aspartate; the mean recovery rates were 50 and 51%, respectively. The limits of detection and quantification were
0.33 956;g mL−1 and 0.6 956;g mL−1, respectively, forl-dihydroorotate and 0.4 956;g mL−1 and 0.7 956;g mL−1 forN-carbamoyl aspartate. This method can be used to assess accumulation ofN-carbamoyl aspartate andl-dihydroorotate in body fluids in situations where cellular pyrimidine de novo synthesis is impaired. 相似文献
89.
T. I. Mukhanova L. M. Alekseeva A. S. Shashkov V. G. Granik 《Chemistry of Heterocyclic Compounds》2004,40(1):16-21
Derivatives of furo[2,3-f]quinoline were synthesized by the reaction of the enamines of acetylacetone and benzoylacetone with 2-methoxycarbonyl-4-oxo-5,8-quinolinequinone. A derivative of pyrrolo[2,3-h]quinoline was obtained from N-benzyl-946.gif" alt="beta" align="MIDDLE" BORDER="0">-aminocrotonic ester. 相似文献
90.
The approaches to the synthesis of various 16945.gif" alt="agr" align="BASELINE" BORDER="0">,17945.gif" alt="agr" align="BASELINE" BORDER="0">-disubstituted pregna-4,9-dien-3,20-diones from the corresponding 9945.gif" alt="agr" align="BASELINE" BORDER="0">-derivatives with labile epoxide, dioxolane, and oxathiolane ringsD have been studied. The transformation has been found to proceed efficiently when the 9945.gif" alt="agr" align="BASELINE" BORDER="0">-sulfinic esters are used at the intermediate stage and then elimination of sulfinic acid by TsOH/SiO2 is carried out.For part 193, see ref. 7.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 983–986, May, 1993. 相似文献