全文获取类型
收费全文 | 2916篇 |
免费 | 50篇 |
国内免费 | 14篇 |
专业分类
化学 | 2058篇 |
晶体学 | 13篇 |
力学 | 76篇 |
数学 | 372篇 |
物理学 | 461篇 |
出版年
2022年 | 23篇 |
2021年 | 28篇 |
2020年 | 18篇 |
2019年 | 32篇 |
2018年 | 29篇 |
2016年 | 46篇 |
2015年 | 40篇 |
2014年 | 51篇 |
2013年 | 166篇 |
2012年 | 131篇 |
2011年 | 129篇 |
2010年 | 97篇 |
2009年 | 98篇 |
2008年 | 126篇 |
2007年 | 138篇 |
2006年 | 140篇 |
2005年 | 147篇 |
2004年 | 128篇 |
2003年 | 111篇 |
2002年 | 114篇 |
2001年 | 49篇 |
2000年 | 50篇 |
1999年 | 31篇 |
1998年 | 26篇 |
1997年 | 35篇 |
1996年 | 50篇 |
1995年 | 33篇 |
1994年 | 40篇 |
1993年 | 38篇 |
1992年 | 27篇 |
1991年 | 40篇 |
1990年 | 29篇 |
1989年 | 19篇 |
1988年 | 18篇 |
1987年 | 23篇 |
1986年 | 16篇 |
1985年 | 46篇 |
1984年 | 51篇 |
1983年 | 32篇 |
1982年 | 41篇 |
1981年 | 36篇 |
1980年 | 48篇 |
1979年 | 43篇 |
1978年 | 55篇 |
1977年 | 44篇 |
1976年 | 34篇 |
1975年 | 40篇 |
1974年 | 39篇 |
1973年 | 39篇 |
1972年 | 17篇 |
排序方式: 共有2980条查询结果,搜索用时 8 毫秒
11.
J. Ramier L. Chazeau C. Gauthier L. Guy M. N. Bouchereau 《Journal of Polymer Science.Polymer Physics》2006,44(1):143-152
The treatment of nanoscopic silica grafted in the blend during the processing of silica‐filled styrene butadiene rubber was performed with silane, introduced at different concentrations, or at a constant concentration with a given length of alkyl chain. From swelling measurements in water and in solvent, the maximum silane content that can be grafted has been calculated as a function of the length of the silane alkyl chains as well as their efficiency to cover the silica surface. The found values are close to the values found in the literature for grafting in solution. Moreover, a direct correspondence between the length of the silane alkyl chains and their concentration has been deduced. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 143–152, 2006 相似文献
12.
13.
14.
Claude Tricot 《Constructive Approximation》1989,5(1):117-136
In fractal modeling, porous surfaces in the plane are usually described as the residual setE of a packing by connected open domains \(C_n\) . In the case whereE is nonempty, we investigate the relationships between the dimensionality ofE and the geometry of the complementary sets \(C_n\) . If they satisfy suitable regularity conditions, then the Bouligand dimension ofE is equal to the exponent of convergence of the series ∑(diam \(C_n\) ) α . We give here general conditions to obtain this equality, together with numerous examples and possible ways of developing this theory. 相似文献
15.
16.
Rüdiger O Abad JM Hatchikian EC Fernandez VM De Lacey AL 《Journal of the American Chemical Society》2005,127(46):16008-16009
The orientation of hydrogenase bound covalently to a pyrolytic graphite edge electrode modified with a 4-aminophenyl monolayer can be modulated via electrostatic interactions during the immobilization step. At low ionic strength and when the amino groups of the electrode surface are mostly protonated, the hydrogenase is immobilized with the negatively charged region that surrounds its 4Fe4S cluster nearer to the protein surface facing the electrode. This allows direct electron transfer between the immobilized hydrogenase and the electrode, which is observed by the strong catalytic currents measured in the presence of the H2 substrate. Therefore, a very stable enzymatic electrode is produced that catalyzes nonmediated H2 oxidation. 相似文献
17.
The kinetics of peptide release during in vitro digestion of 4 protein sources (casein, cod protein, soy protein, and gluten) were investigated. Samples were sequentially hydrolyzed with pepsin (30 min) and pancreatin (2, 4, or 6 h) in a dialysis cell with continuous removal of digestion products. Nondialyzed digests were fractionated by ion-exchange chromatography and ultrafiltration. Animal proteins were digested at a greater rate than plant proteins. Target amino acids of specific enzymes appeared more rapidly in the dialyzed fractions when compared to other amino acids. Throughout the hydrolysis, nondialyzed digests contained a higher proportion of peptide mixtures with basic-neutral properties. Except for gluten, peptide fractions with molecular weights that exceeded 10 kDa (basic-neutral, BN > 10) were rapidly hydrolyzed during the first 2 h of pancreatin digestion. The kinetics of release and the composition of peptide fractions were different when the protein sources were compared. The analysis of amino acids revealed that threonine and proline proportions were relatively high in BN > 10 and in peptide fractions with molecular weight between 10-1 kDa (BN 10-1), while tyrosine, phenylalanine, lysine, and arginine predominated in the low molecular weight (<1 kDa) fractions. More resistant peptides were generally rich in proline and glutamic acid. The role of in vitro digestion assays in dietary protein quality evaluation is discussed. 相似文献
18.
The voltammogram of aryldiazonium tetrafluoroborates in acetonitrile (ACN), at low concentration, shows a first one-electron wave followed at a more negative potential by a small second wave; this last one corresponds to the reduction of the radical formed at the level of the first wave. Simulation of the voltammogram permits one to determine the standard redox potential of the radical/anion couple Eo(Ph./Ph-) = 0.05 V/SCE and the reduction mechanism of the diazonium cation. An electron transfer concerted with the cleavage of the C-N bond furnishes the aryl radical; this radical undergoes two competitive reactions: reduction at the electrode and H-atom transfer. 相似文献
19.
Claude Moncuit 《Theoretical chemistry accounts》1975,39(3):255-276
The oscillator strengths of the “d-d” transitions of the ion [PtCl4]2? were calculated. The method, based on the evaluation of the MO of the distorted ion, gives results in good accordance with the experimental data. The transition to 1 B 1g (a 1g →b 1g * ), as a consequence of the participation of the orbital 6s, mixed with \(5d_{z^2 } \) in \(a_{1_g } ,a_{1_g } \) is characterized by a very low intensity in the case of thex,y polarization. 相似文献
20.