全文获取类型
收费全文 | 4687篇 |
免费 | 84篇 |
国内免费 | 22篇 |
专业分类
化学 | 3022篇 |
晶体学 | 29篇 |
力学 | 172篇 |
数学 | 690篇 |
物理学 | 880篇 |
出版年
2022年 | 30篇 |
2021年 | 33篇 |
2020年 | 35篇 |
2019年 | 37篇 |
2018年 | 42篇 |
2017年 | 40篇 |
2016年 | 69篇 |
2015年 | 85篇 |
2014年 | 98篇 |
2013年 | 255篇 |
2012年 | 193篇 |
2011年 | 224篇 |
2010年 | 135篇 |
2009年 | 132篇 |
2008年 | 194篇 |
2007年 | 181篇 |
2006年 | 199篇 |
2005年 | 213篇 |
2004年 | 182篇 |
2003年 | 169篇 |
2002年 | 172篇 |
2001年 | 67篇 |
2000年 | 80篇 |
1999年 | 76篇 |
1998年 | 52篇 |
1997年 | 79篇 |
1996年 | 81篇 |
1995年 | 70篇 |
1994年 | 64篇 |
1993年 | 73篇 |
1992年 | 65篇 |
1991年 | 68篇 |
1990年 | 52篇 |
1989年 | 54篇 |
1988年 | 41篇 |
1987年 | 39篇 |
1985年 | 85篇 |
1984年 | 71篇 |
1983年 | 59篇 |
1982年 | 74篇 |
1981年 | 77篇 |
1980年 | 62篇 |
1979年 | 73篇 |
1978年 | 70篇 |
1977年 | 84篇 |
1976年 | 58篇 |
1975年 | 58篇 |
1974年 | 53篇 |
1973年 | 44篇 |
1971年 | 38篇 |
排序方式: 共有4793条查询结果,搜索用时 15 毫秒
981.
982.
983.
984.
985.
Joel M. Gichumbi Bernard Omondi Kovashnee Naicker Moganavelli Singh Hafizah Y. Chenia 《Journal of Coordination Chemistry》2018,71(2):342-354
New osmium(II)-arene complexes [(η6-C6H6)OsCl(C5H4N-2-CH=N-C6H5X)](PF6) (X = p-flouro (1), p-chloro (2), p-methyl (3)) were synthesized by reaction of the corresponding bidentate N,N′-ligands with the osmium-arene precursor [(η6-C6H6)Os(μ-Cl)Cl]2 in a 2:1 ratio. These complexes were characterized by UV–Vis, IR, 1H, 13C NMR spectroscopy, and elemental analysis and, for compound 1, a single crystal X-ray structure was also obtained. The complexes were investigated for antiproliferative activity in vitro against MCF-7 (human breast adenocarcinoma), Caco-2 (human epithelial colorectal adenocarcinoma), and HepG2 (human hepatocellular carcinoma) tumor cell lines. To test their selectivity, the non-tumor HEK293 (human embryonic kidney) cell line was used. The compounds were selective toward the tumor cell lines when compared to the known anticancer drug 5-fluorouracil which displayed low selectivity. The compounds were substantially more active against Caco-2 than 5-fluorouracil. They also showed moderate activity against the other two tumor cell lines. In addition, the antimicrobial activity of complex 2 was explored against a panel of antimicrobial-susceptible and -resistant Gram-negative and Gram-positive bacteria. Complex 2 showed anti-mycobacterial activity against Mycobacterium smegmatis and bactericidal activity against drug-resistant Enterococcus faecalis and methicillin-resistant Staphylococcus aureus ATCC 43300. 相似文献
986.
Surfactant Assembly within Pickering Emulsion Droplets for Fabrication of Interior‐Structured Mesoporous Carbon Microspheres 下载免费PDF全文
Dawei Liu Nan Xue Lijuan Wei Dr. Ye Zhang Prof. Zhangfeng Qin Prof. Xuekuan Li Prof. Bernard P. Binks Prof. Hengquan Yang 《Angewandte Chemie (International ed. in English)》2018,57(34):10899-10904
Large‐sized carbon spheres with controllable interior architecture are highly desired, but there is no method to synthesize these materials. Here, we develop a novel method to synthesize interior‐structured mesoporous carbon microspheres (MCMs), based on the surfactant assembly within water droplet‐confined spaces. Our approach is shown to access a library of unprecedented MCMs such as hollow MCMs, multi‐chambered MCMs, bijel‐structured MCMs, multi‐cored MCMs, “solid” MCMs, and honeycombed MCMs. These novel structures, unattainable for the conventional bulk synthesis even at the same conditions, suggest an intriguing effect arising from the droplet‐confined spaces. This synthesis method and the hitherto unfound impact of the droplet‐confined spaces on the microstructural evolution open up new horizons in exploring novel materials for innovative applications. 相似文献
987.
Bernard Coupet Alexander Sukhov 《Proceedings of the American Mathematical Society》1996,124(11):3371-3380
We prove that a piecewise smoothly bounded strictly pseudoconvex domain with a non--compact automorphism group is biholomorphic to the ball. A boundary version of the Schwarz lemma for automorphisms of such a domain is settled.
988.
Alain Lascoux Bernard Leclerc Jean-Yves Thibon 《Communications in Mathematical Physics》1996,181(1):205-263
We present a fast algorithm for computing the global crystal basis of the basic
-module. This algorithm is based on combinatorial techniques which have been developed for dealing with modular representations of symmetric groups, and more generally with representations of Hecke algebras of typeA at roots of unity. We conjecture that, upon specializationq1, our algorithm computes the decomposition matrices of all Hecke algebras at an
th root of 1.Partially supported by PRC Math-Info and EEC grant n0 ERBCHRXCT930400. 相似文献
989.
990.
Noise in spontaneous respiratory neural activity of the neonatal rat isolated brainstem-spinal cord preparation stimulated with acetylcholine (ACh) exhibits positive correlation. Neural activity from the C4 (phrenic) ventral spinal rootlet, integrated and corrected for slowly changing trend, is interpreted as a fractal record in time by rescaled range, relative dispersional, and power spectral analyses. The Hurst exponent H measured from time series of 64 consecutive signal levels recorded at 2 s intervals during perfusion of the preparation with artificial cerebrospinal fluid containing ACh at concentrations 62.5 to 1000 &mgr;M increases to a maximum of 0.875+/-0.087 (SD) at 250 &mgr;M ACh and decreases with higher ACh concentration. Corrections for bias in measurement of H were made using two different kinds of simulated fractional Gaussian noise. Within limits of experimental procedure and short data series, we conclude that in the presence of added ACh of concentration 250 to 500 &mgr;M, noise which occurs in spontaneous respiratory-related neural activity in the isolated brainstem-spinal cord preparation observed at uniform time intervals exhibits positive correlation. (c) 1995 American Institute of Physics. 相似文献