全文获取类型
收费全文 | 1365篇 |
免费 | 37篇 |
国内免费 | 5篇 |
专业分类
化学 | 1097篇 |
晶体学 | 12篇 |
力学 | 11篇 |
综合类 | 1篇 |
数学 | 58篇 |
物理学 | 228篇 |
出版年
2021年 | 12篇 |
2020年 | 29篇 |
2019年 | 18篇 |
2018年 | 15篇 |
2017年 | 9篇 |
2016年 | 22篇 |
2015年 | 25篇 |
2014年 | 28篇 |
2013年 | 64篇 |
2012年 | 65篇 |
2011年 | 75篇 |
2010年 | 45篇 |
2009年 | 47篇 |
2008年 | 87篇 |
2007年 | 87篇 |
2006年 | 79篇 |
2005年 | 76篇 |
2004年 | 90篇 |
2003年 | 79篇 |
2002年 | 51篇 |
2001年 | 26篇 |
2000年 | 31篇 |
1999年 | 29篇 |
1998年 | 17篇 |
1997年 | 24篇 |
1996年 | 20篇 |
1995年 | 16篇 |
1994年 | 11篇 |
1993年 | 11篇 |
1992年 | 21篇 |
1991年 | 13篇 |
1990年 | 15篇 |
1989年 | 15篇 |
1988年 | 9篇 |
1987年 | 14篇 |
1986年 | 4篇 |
1985年 | 17篇 |
1984年 | 11篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 13篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1977年 | 3篇 |
1976年 | 9篇 |
1975年 | 9篇 |
1974年 | 3篇 |
1973年 | 6篇 |
1967年 | 4篇 |
排序方式: 共有1407条查询结果,搜索用时 218 毫秒
111.
Sasaki K Sugou K Miyamoto K Hirai J Tsubouchi S Miyasaka H Itaya A Kuroda Y 《Organic & biomolecular chemistry》2004,2(19):2852-2860
The nonameric porphyrin assemblies constructed with the series of free base tetraphenylporphyrins Pn having four pyrazine moieties linked with alkyl chains of different lengths, (CH2)n (n = 1, 5, 9, 17, 30), and dimeric [meso-tetrakis(2-carboxy-4-nonylphenyl)porphyrinato]zinc(II), ZnP2, show the effective light-collection effect and the typical Forster-type energy transfer from ZnP2 to Pn. 相似文献
112.
113.
Tsuboyama A Takiguchi T Okada S Osawa M Hoshino M Ueno K 《Dalton transactions (Cambridge, England : 2003)》2004,(8):1115-1116
The synthesis, structure, and photophysical properties of a new cyclometalated dinuclear iridium complex, (ppy)2Ir(mu-BPB)Ir(ppy)2 [ppy = 2-phenylpyridine, BPB = 1,4-bis(pyridin-2-yl)benzene], have been investigated. 相似文献
114.
Itaka K Kanayama N Nishiyama N Jang WD Yamasaki Y Nakamura K Kawaguchi H Kataoka K 《Journal of the American Chemical Society》2004,126(42):13612-13613
An siRNA nanocarrier formed through self-assembly of PEG-based block catiomer possessing two distinct amino groups with different pKa values in a side chain was developed. This design provided the carrier with a sufficient siRNA complexation and an assumed buffering capacity in the endosomes, allowing it to exhibit remarkable gene knockdown abilities as well as sufficient serum tolerability. 相似文献
115.
Ikeda S Sanuki R Miyachi H Miyashita H Taniguchi M Odashima K 《Journal of the American Chemical Society》2004,126(33):10331-10338
A Ni(0)/ZnCl(2) system effectively promotes the coupling of enones and alkene-tethered alkynes. In the reaction with 1,6-enynes, the oxidative cyclization of Ni(0) species on enones across the alkyne part followed by ZnCl(2)-promoted cleavage generates alkenylnickel intermediates. Subsequent migratory insertion of the tethered alkene occurs with 5-exo-cyclization. When the resulting sigma-alkylnickel intermediates have beta-hydrogen atoms, the reaction terminates by beta-hydrogen elimination to provide cyclopentane derivatives. On the other hand, a sigma-alkylnickel intermediate that does not have beta-hydrogen atoms undergoes the insertion of a second alkene unit to cause a domino effect via a three-fold C-C bond formation process with and without the cleavage of one C-C bond. 相似文献
116.
Cationic chiral palladium(ii) complexes are shown to catalyze the asymmetric coupling reaction of aryl boronates and aryl halides within a short period of time in good yield and enantioselectivity. 相似文献
117.
118.
Polyion complex micelles entrapping enzyme molecules in the core provide a unique reaction field inducing a remarkable elevation of enzymatic reactivity through a drastic change in the binding specificity between the enzyme and substrate. On-off switching of this enhanced effect was achieved through the destabilization of the core domain by applying a pulse electric field. 相似文献
119.
Sugiyasu K Fujita N Takeuchi M Yamada S Shinkai S 《Organic & biomolecular chemistry》2003,1(5):895-899
A 1,10-phenanthroline-appended cholesterol-based gelator (1) and its nongelling reference compound (2) were synthesized. Among 19 solvents tested herein, gelator 1 could gelate 11 solvents including alcohols, dipolar aprotic solvents, organic acids and a base (triethylamine), indicating that 1 acts as a versatile gelator. The TEM observation gave a visual image showing that fibrillar aggregates are entangled in the three-dimensional network structure. In the fluorescence measurements, most gels afforded an emission maximum at 394 nm (purple emission), whereas only the acetic acid gel afforded an emission maximum at 522 nm (yellow emission). Thus, the influence of protonation of the 1,10-phenanthroline nitrogens (by trifluoroacetic acid) on the fluorescence properties in the gel phase was investigated in detail. The results have established that the fluorescence intensity of 1 x H+ becomes particularly strong in the gel phase, presumably because of the energy transfer from neutral 1* to protonated 1 x H+ and the restriction of the 1 x H+ molecular motion. The finding suggests the possibility that the gel system would be useful not only as a new proton-sensitive fluorescence system but also as a new medium for designing efficient energy transfer systems. 相似文献
120.
Kazunori Kodaka Hiroyuki Osaka 《Proceedings of the American Mathematical Society》2001,129(4):999-1003
A -algebra is said to have the FS-property if the set of all self-adjoint elements in has a dense subset of elements with finite spectrum. We shall show that this property is not stable under taking the minimal -tensor products even in case of separable nuclear -algebras.