全文获取类型
收费全文 | 386063篇 |
免费 | 3187篇 |
国内免费 | 981篇 |
专业分类
化学 | 206929篇 |
晶体学 | 6063篇 |
力学 | 17163篇 |
综合类 | 12篇 |
数学 | 41676篇 |
物理学 | 118388篇 |
出版年
2020年 | 3019篇 |
2019年 | 3320篇 |
2018年 | 4386篇 |
2017年 | 4411篇 |
2016年 | 6494篇 |
2015年 | 3940篇 |
2014年 | 6171篇 |
2013年 | 15731篇 |
2012年 | 11911篇 |
2011年 | 14650篇 |
2010年 | 10443篇 |
2009年 | 10293篇 |
2008年 | 13895篇 |
2007年 | 13862篇 |
2006年 | 13182篇 |
2005年 | 11921篇 |
2004年 | 10928篇 |
2003年 | 10021篇 |
2002年 | 9869篇 |
2001年 | 11782篇 |
2000年 | 8891篇 |
1999年 | 6869篇 |
1998年 | 5511篇 |
1997年 | 5600篇 |
1996年 | 5272篇 |
1995年 | 4896篇 |
1994年 | 5045篇 |
1993年 | 4578篇 |
1992年 | 5468篇 |
1991年 | 5530篇 |
1990年 | 5346篇 |
1989年 | 5183篇 |
1988年 | 5273篇 |
1987年 | 5123篇 |
1986年 | 4816篇 |
1985年 | 6320篇 |
1984年 | 6572篇 |
1983年 | 5409篇 |
1982年 | 5523篇 |
1981年 | 5336篇 |
1980年 | 5291篇 |
1979年 | 5513篇 |
1978年 | 5898篇 |
1977年 | 5793篇 |
1976年 | 5763篇 |
1975年 | 5352篇 |
1974年 | 5432篇 |
1973年 | 5577篇 |
1972年 | 3876篇 |
1971年 | 3186篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
Optical properties of thiopyrimidine nucleosides 总被引:1,自引:0,他引:1
992.
Condensation of α-halocarbonyl compounds and 2-mercaptobenzimidazole gives thiazolo-[3,2-a]benzimidazoles. This condensation occurred at the mercapto group of the benzimidazole followed by cyclization to form the thiazole ring. This was confirmed by the examination of the mass spectra of 2- and 3-methylthiazolo[3,2-a]benzimidazoles, 2- and 3-phenylthiazolo[3,2-a]-benzimidazoles, and their derivatives. 相似文献
993.
G. Gritzner 《Fresenius' Journal of Analytical Chemistry》1967,230(3):231
Ohne Zusammenfassung 相似文献
994.
995.
996.
997.
998.
A. V. Kashevskii M. A. Mamalyga T. L. Petrova A. Yu. Safronov V. N. Kizhnyaev 《Russian Journal of Applied Chemistry》2007,80(2):316-321
Copolymers of 1-vinyl-1,2,4-triazole and 5-vinyltetrazole with 1,1,5-trihydrooctafluoropentyl methacrylate and 1,1,7-trihydrododecafluoroheptyl methacrylate were prepared under the conditions of radical initiation. These copolymers were used for modification of the surface of a glassy carbon electrode, and the effect of the modification on the electrochemical behavior of the electrode in anodic oxidation of dopamine and NO was studied. The possibility of enhancing the selectivity of the electrochemical sensor for monitoring NO in biological media was demonstrated. 相似文献
999.
N. S. Shaglaeva O. V. Lebedeva Yu. N. Pozhidaev R. G. Sultangareev S. S. Bochkareva L. A. Es’kova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(3):335-338
Hybrid organoinorganic composites insoluble in water and organic solvents were prepared by the hydrolysis of tetraethoxysilane in the presence of poly-1-vinylpyrazole, poly-1-vinylimidazole, and poly-4-vinylpyridine. The composition of the composites was determined by the nature of the polymeric nitrogen base and hydrolysis conditions. The composites synthesized showed high sorption activity in the extraction of the [PdCl4]2?, [PtCl6]2?, and [AuCl4]? ions from hydrochloric acid solutions. 相似文献
1000.
The conjugate of mitomycin C (MMC) with linear (1----3)-beta-D-glucan from Alcaligenes faecalis var. myxogenes IFO 13140 was synthesized and its antitumor activities investigated. The conjugate (MMC-carboxymethylated linear (1----3)-beta-D-glucan (CMPS)) was obtained by treatment of CMPS with MMC in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide. In vitro cytotoxicity of MMC-CMPS against L1210 leukemia cells was similar to that of MMC. In i.p.-i.p. system in vivo against P388 leukemia in mice, the maximum increase of MMC-CMPS conjugate in life span (ILSmax) was higher than that of MMC but the therapeutic index was reduced. However, the antitumor activity of MMC-CMPS conjugate against subcutaneously implanted sarcoma 180 solid tumor in mice by i.p. administration was similar to that of MMC at a dose of 1.5 mg eq MMC/kg/d x 7 and the reduction of the number of leukocytes caused by MMC was suppressed by attaching MMC to CMPS. In addition, on assay using serum of sarcoma 180 solid tumor-bearing mice with injection of MMC-CMPS conjugate, a drastic loss of tumor cells and an increase in polymorphonuclear leukocytes (PMN) were observed. This result suggested that MMC-CMPS conjugate induced tumor-regressing factor similar to CMPS. 相似文献