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731.
Y. S. Mok H.-C. Kang H.-J. Lee D. J. Koh D. N. Shin 《Plasma Chemistry and Plasma Processing》2010,30(4):437-447
Reduction of carbon monoxide to methane by hydrogen was investigated with a nonthermal plasma reactor in which Ni/alumina
catalyst pellets was filled. The effect of reaction temperature, pressure and voltage on the conversion of CO was examined.
It was found that the nonthermal plasma significantly enhanced the catalytic conversion of CO. The effect of the nonthermal
plasma was especially remarkable at lower temperatures and pressures. At high temperatures, the catalyst itself exhibited
very high catalytic activity for the conversion of CO. Since high pressure is unfavorable for creating electrical discharge
plasma, the increase in pressure lowered the discharge power, thereby weakening the effect of the nonthermal plasma. With
the nonthermal plasma alone, there was no conversion of CO. The reaction products identified by FTIR spectra were CH4, CO2 and H2O. FTIR spectra also showed that CO was converted primarily into CH4 with high selectivity above 90% at most experimental conditions. 相似文献
732.
To identify genes that are modulated under cold-stress conditions in the earthworm Eisenia andrei, we performed a genome-wide analysis of gene expression in cold-shocked earthworms by using Serial Analysis of Gene Expression (SAGE). We identified 5,977 and 5,407 unique SAGE tags under normal and cold-stressed conditions, respectively. The majority of the SAGE tags did not match to any known expressed sequences, due to a paucity of expression data in earthworms. We converted the statistically significant SAGE tags for the cold-stressed condition into expressed sequence tags (ESTs), and the results showed that particular genes associated with energy homeostasis, cellular defense mechanisms, and ion balance were up-regulated or down-regulated. We constructed a regulatory network of some of these genes and identified rps-6 as a core gene in the cold-response regulatory-gene network. Our data provide a baseline for gene expression studies of cold shock in the Lumbricidae. 相似文献
733.
Dr. Yi Wei Dr. Quanquan Wang Prof. Dr. Ming Joo Koh 《Angewandte Chemie (International ed. in English)》2023,62(5):e202214247
C-Alkyl glycosides and glycoproteins exist in natural products and are prized for their role as carbohydrate mimics in drug design. However, a practical strategy that merges glycosyl donors with readily accessible reagents, derived from abundant carboxylic acid and amine feedstocks, is yet to be conceived. Herein, we show that a nickel catalyst promotes C−C coupling between glycosyl halides and aliphatic acids or primary amines (converted into redox-active electrophiles in one step), in the presence of Hantzsch ester and LiI (or Et3N) under blue LED illumination to deliver C-alkyl glycosides with high diastereoselectivity. Mechanistic studies support the photoinduced formation of alkyl radicals that react with a glycosyl nickel species generated in situ to facilitate cross-coupling. Through this manifold, innate CO2H and NH2 motifs embedded within amino acids and oligopeptides are selectively capped and functionalized to afford glycopeptide conjugates through late-stage glycosylation. 相似文献
734.
The synthesis and isolation of the first examples of a tetraselenolane and a hexaselenepane, obtained from the reaction of a bissilylcarbenoid (RSi2CBrLi; RSi=SiMePh2) with elemental selenium, is reported. The molecular structures of these cyclic polyselenides were determined using single-crystal X-ray diffraction analysis. The selective synthesis of these polyselenides was achieved by controlling the reaction temperature. Stoichiometric deselenation of the hexaselenepane with triphenylphosphine afforded the corresponding tetraselenolane in quantitative yield. Further deselenation of the tetraselenolane with excess triphenylphosphine did not furnish the expected selenoketone but the diselenirane, as confirmed by spectroscopic analysis. 相似文献
735.
Koh‐hei Nitta 《Macromolecular Symposia》2001,170(1):311-319
In this work, a molecular model is proposed to account for the stress‐strain relationships of spherulitic polymers. To describe the yielding behavior of spherulitic polymers, we introduced a new structural unit, i.e. the lamellar cluster, which is represented by several stacked lamellae bound by some tie molecules. It was shown that the tie molecules between the adjacent lamellar clusters produce the concentrated load acting on the cluster surface, leading to bending deformation of the lamellar cluster. The yielding behavior was explained by the disintegration of lamellar cluster due to the bending deformation. 相似文献
736.
The structure ofS the title complex [Co. L. (H2O)3]n. nH2O. 0.2 nH2O has been established by single crystal X-ray diffraction. Crystals of the complex are monoclinic, space group C2/c with cell constants α = 45.29(4), b=10.631(6), c = 8.015(6) Å, β = 90.65(8)°, Z = 8, Dc = 1.489 g. cm−3 The structure was solved and refined to R =0.0478 (wR = 0.0577). In the chain structure, Co(II) ions are hexacoordinated by 0 atoms in an octahedral arrangement. CoO6 octahedra share corners (bridged) through O atoms of water, with each L2--ligand binding two adjacent Co atoms. 相似文献
737.
Si1-xGex mixed crystals with 5 at% Ge concentration have been grown by the pulling-down technique using a crucible with multi-capillary channels. The unique feature of the technique is that Ge solute concentration of the small molten zone is maintained constant due to the condition of no back diffusion of solute through the capillary channels, and that the diffusion-controlled solute transport causes the effective distribution coefficient to be unity. The Ge concentration was measured by the electron probe microanalysis and observed to be homogeneous along both the longitudinal and radial directions. The two-dimensional distribution on the whole cross section was also found to be uniform. 相似文献