全文获取类型
收费全文 | 890篇 |
免费 | 24篇 |
国内免费 | 6篇 |
专业分类
化学 | 616篇 |
晶体学 | 5篇 |
力学 | 5篇 |
数学 | 30篇 |
物理学 | 264篇 |
出版年
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 16篇 |
2019年 | 9篇 |
2018年 | 7篇 |
2017年 | 4篇 |
2016年 | 17篇 |
2015年 | 14篇 |
2014年 | 13篇 |
2013年 | 39篇 |
2012年 | 44篇 |
2011年 | 54篇 |
2010年 | 20篇 |
2009年 | 28篇 |
2008年 | 58篇 |
2007年 | 66篇 |
2006年 | 65篇 |
2005年 | 63篇 |
2004年 | 44篇 |
2003年 | 31篇 |
2002年 | 42篇 |
2001年 | 23篇 |
2000年 | 20篇 |
1999年 | 8篇 |
1997年 | 7篇 |
1996年 | 7篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 19篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 5篇 |
1988年 | 12篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 13篇 |
1984年 | 12篇 |
1983年 | 9篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 9篇 |
1978年 | 6篇 |
1977年 | 8篇 |
1976年 | 3篇 |
1975年 | 5篇 |
1974年 | 7篇 |
1973年 | 8篇 |
1968年 | 4篇 |
1964年 | 3篇 |
排序方式: 共有920条查询结果,搜索用时 15 毫秒
1.
K Kawasaki T Tsuji K Hirase M Miyano Y Imoto M Iwamoto 《Chemical & pharmaceutical bulletin》1991,39(3):584-589
N-Terminal tripeptide analogs of fibrin alpha-chain were synthesized and their inhibitory effect on fibrinogen/thrombin clotting was examined. A new water-soluble active ester, 3-pyridinium ester, was used for the synthesis. Among the synthetic peptides, H-Gly-Pro-Arg-hexamethyleneimine exhibited the highest inhibitory effect on fibrinogen-thrombin clotting. 相似文献
2.
Arata Yajima Ayumi Yamaguchi Fumihiro Saitou Tomoo Nukada Goro Yabuta 《Tetrahedron》2007,63(5):1080-1084
A convergent synthetic strategy for abietane diterpenoids via B-alkyl Suzuki-Miyaura coupling and Lewis acid-mediated cyclization reactions is established. Asymmetric total synthesis of 12-deoxyroyleanone, an antileishmanial diterpene, is described. 相似文献
3.
The projector formalism of Zwanzig-Mori type is extended to obtain generalized Fokker-Planck and generalized nonlinear Langevin equations for coarse-grained variables when the underlying microscopic dynamics is dissipative and noisy (stochastic). 相似文献
4.
Fumio Sanda Ritsuya Kawasaki Masashi Shiotsuki Toshio Masuda 《Journal of polymer science. Part A, Polymer chemistry》2007,45(19):4450-4458
Novel chiral acetylene monomers containing carbazole, 2‐ethynyl‐9‐[(S)‐2‐methylbutoxycarbonyl]carbazole ( 1 ), 3‐ethynyl‐9‐[(S)‐2‐methylbutoxycarbonyl]carbazole ( 2 ), 2‐ethynyl‐9‐[(S)‐2‐methylbutyl]carbazole ( 3 ), and 2‐ethynyl‐9‐[(S)‐4‐methylhexyl]carbazole ( 4 ) were synthesized and polymerized with [(nbd)RhCl]2? Et3N. The corresponding polyacetylenes with number‐average molecular weights ranging from 68,700 to 310,000 were obtained in good yields. Poly( 1 ) exhibited a large specific rotation and an intense Cotton effect in toluene, indicating that it formed a helix with predominantly one‐handed screw sense, while the other three polymers showed no evidence for taking a helical structure. Poly( 1 ) largely decreased the CD intensity upon heating from ?10 to 60 °C. Poly( 1 ) showed a Cotton effect in film state in a manner similar to solution state. No chiral amplification was observed in the copolymerization of 1 with achiral 2‐ethynyl‐9‐tert‐butoxycarbonylcarbazole ( 5 ). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4450–4458, 2007 相似文献
5.
Hidefumi Kawasaki 《Mathematical Programming》1988,41(1-3):327-339
The purpose of this paper is to give a formula for expressing the second order directional derivatives of the sup-type functionS(x) = sup{f(x, t); t T} in terms of the first and second derivatives off(x, t), whereT is a compact set in a metric space and we assume thatf, f/x and
2
f/x
2 are continuous on
n
× T. We will give a geometrical meaning of the formula. We will moreover give a sufficient condition forS(x) to be directionally twice differentiable. 相似文献
6.
7.
Summary The equation for the potential energy of interactions established for gas-liquid chromatography has been confirmed in reversed phase liquid chromatography. Equations derived for molecular polarizabilities of PAHs and their retention data have very high correlation coefficients. The results indicate that the inductive effect between solute and stationary phase is the main one and the dispersive effect is very small compared with the inductive effect but its contribution increases with the carbon chain length of the stationary phase. 相似文献
8.
9.
Racemic 2-amino-3-(heteroaryl)propanoic acids (1), mostly with a furan or thiophene nucleus as a heteroaryl group, were synthesized in 48-94% yield by the reduction of 3-(heteroaryl)-2-(hydroxyimino)propanoic acids (5) with zinc dust and formic acid in the presence of a catalytic amount of iron dust at 60 degrees C for 2 h. Under these conditions, unfavorable hydrogenolysis of bromine on the thiophene nucleus does not occur. Traditional N-formylation of the prepared 3-(heteroaryl)alanine (1) with a mixture of formic acid and acetic anhydride afforded 2-(formylamino)-3-(heteroaryl)propanoic acids (6) in 51-95% yield. 相似文献
10.
We investigate the equilibrium dynamics of our recently proposed toy model of dense fluid in the infinite damping limit. Contrary to naive expectation, the correlators involving the velocity-like variables do not quickly relax away. Instead, after a very fast transient relaxation, they exhibit rather slow relaxations due to the coupling to the density-like variable. Hence, the so-called "hopping" processes are not suppressed even in the large damping limit. These hopping processes can only be controlled by tuning the parameter delta, which is the ratio of the numbers of the components of the velocity-like and the density-like variables in the model. We analytically prove that there must exist an ergodic-to-nonergodic phase transition for delta such that 0 < delta < 1. The slow dynamics and the dynamic transition in the model are distinct from those in the idealized mode coupling theory. 相似文献