全文获取类型
收费全文 | 1065篇 |
免费 | 44篇 |
国内免费 | 2篇 |
专业分类
化学 | 868篇 |
晶体学 | 16篇 |
力学 | 17篇 |
数学 | 26篇 |
物理学 | 184篇 |
出版年
2022年 | 6篇 |
2021年 | 10篇 |
2020年 | 10篇 |
2019年 | 16篇 |
2018年 | 5篇 |
2016年 | 26篇 |
2015年 | 16篇 |
2014年 | 32篇 |
2013年 | 51篇 |
2012年 | 53篇 |
2011年 | 53篇 |
2010年 | 47篇 |
2009年 | 27篇 |
2008年 | 39篇 |
2007年 | 52篇 |
2006年 | 62篇 |
2005年 | 62篇 |
2004年 | 71篇 |
2003年 | 44篇 |
2002年 | 45篇 |
2001年 | 26篇 |
2000年 | 21篇 |
1999年 | 16篇 |
1998年 | 5篇 |
1997年 | 11篇 |
1996年 | 24篇 |
1995年 | 17篇 |
1994年 | 8篇 |
1993年 | 13篇 |
1992年 | 10篇 |
1991年 | 17篇 |
1990年 | 9篇 |
1989年 | 16篇 |
1988年 | 11篇 |
1987年 | 12篇 |
1986年 | 18篇 |
1985年 | 16篇 |
1984年 | 19篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 11篇 |
1980年 | 9篇 |
1979年 | 13篇 |
1978年 | 9篇 |
1977年 | 10篇 |
1976年 | 8篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 7篇 |
1968年 | 3篇 |
排序方式: 共有1111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.
Seiichi Iwamoto 《Journal of Mathematical Analysis and Applications》2004,292(1):73-83
This note solves a finite-horizon stochastic optimization problem with forward recursive criterion through dynamic programming. The forward recursive criterion is wide; it includes additive (discounted), multiplicative (discounted risk-sensitive), minimum and terminal criteria. The basic idea is to apply invariant imbedding method for the stochastic optimization. The method incorporates recursive accumulation process into dynamics by expanding the original state space. 相似文献
3.
Investigation of one step synthesis of 2-substituted 3-tri-(or di-)fluoromethyl-2-propenals has been carried out using versatile aldehydes, tri- or di-fluoroacetaldehyde ethyl hemiacetal in the presence of diethylaminotrimethylsilane (DEATMS) in an ionic liquid, and it was demonstrated that this route enabled us to successfully construct 2-substituted 3-tri-(or di-)fluoromethyl-2-propenals with the high level selectivity of geometric isomers. 相似文献
4.
Yoshio Moriya Shinichi Nakata Hirotaka Morimoto Nobuaki Ogawa 《Analytical sciences》2004,20(11):1533-1536
Analysis by reflection spectrometry was performed to clarify the interfacial adsorption of protonated lipophilic tetraphenylporphyrin derivatives in a dodecane-aqueous sulfuric acid system, and to confirm the utility of partial reflection spectroscopy. Interfacial adsorption was not observed for porphyrins substituted at the 2,6 positions of meso-phenyl groups, suggesting that the substituents prevent porphyrins from forming aggregates by steric hindrance. Polymorphous J-aggregates of acid dications were produced by tetra-p-tolylporphyrin with a saturated interfacial molecular density of 1.0 x 10(-10) mol cm(-2), which could yield 48 degrees as a mean tilting angle of the pyrrole ring plane from the interface normal. Partial-reflection spectrometry can provide sensitive detection and molecular orientation analysis of interfacial adsorbates. 相似文献
5.
The propagation characteristics of shear horizontally polarized (SH) waves passing through (Ni42Nb28Zr30)100–x Hx (x = 0–15.2) glassy alloys were investigated as a function of hydrogen content. With an increase in hydrogen content, the propagation time and main frequency of the receiving waves show increase and decrease, respectively, indicating expan‐ sion in average atomic distance which comes from solution of hydrogen. In sharp contrast to crystalline alloys, the decrease in damping ratio and the delay in phase with increasing hydrogen suggest a strong settlement of hydrogen into four‐coordination sites surrounded tetrahedrally by four Zr atoms and the resulting increase in dynamic elasticity, respectively. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
6.
7.
Hatsuo Yamamura Kousuke Satake Rieko Hirasawa Shinichi Yamada Masao Kawai 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):261-264
A novel cyclodextrin (CD) dimer linked with a bis(picolinyl)cystine (Cys) moiety was prepared by the coupling of Boc-protected
Cys with amino-modified CDs, followed by deprotection of the Boc groups and bispicolinylation. The dimer showed less affinity
to an organic guest molecule compared to that of a native CD monomer. It was attributed to an intramolecular inclusion of
the pyridine moiety into CD cavity. The dimer caused significant increase of its organic guest affinity by an addition of
a copper ion. The included pyridine group may come out of a CD cavity to bind the copper ion and the two CDs included cooperatively
and intermolecularly a guest molecule with high affinity. 相似文献
8.
9.
Uesato S Taniuchi K Kumagai A Nagaoka Y Seto R Hara Y Tokuda H Nishino H 《Chemical & pharmaceutical bulletin》2003,51(12):1448-1450
In the course of an exploratory investigation of antitumor-promoting catechins, 3-O-acyl-(+)-catechins of varying carbon lengths from C(4) to C(18) were assessed for inhibitory effects on the activation of the Epstein-Barr virus early antigen. Like 3-O-acyl-(-)-epigallocatechins, the (+)-catechin derivatives showed promising effects with the C-3 acyl chain of C(8)-C(11) carbon atoms. 相似文献
10.
Vascular dilatory action of the Chinese crude drug. II. Effects of scoparone on calcium mobilization 总被引:1,自引:0,他引:1
J Yamahara G Kobayashi H Matsuda M Iwamoto H Fujimura 《Chemical & pharmaceutical bulletin》1989,37(2):485-489
Further experiments were conducted to examine the effect of scoparone (6,7-dimethoxycoumarin), a coumarin derivative found in the Chinese crude drug "Capillaris Flos," on calcium mobilization. Scoparone does not affect Ca2+ influx through the voltage-dependent channel due to membrane depolarization. Its inhibitory action may be dependent not only on the inhibition of Ca2+ release from sarcoplasmic reticulum but also on the inhibition of extracellular Ca2+ influx through the receptor-operated channel. 相似文献