全文获取类型
收费全文 | 1242801篇 |
免费 | 127926篇 |
国内免费 | 861篇 |
专业分类
1371588篇 |
出版年
2018年 | 11780篇 |
2016年 | 15751篇 |
2015年 | 20713篇 |
2014年 | 24429篇 |
2013年 | 34872篇 |
2012年 | 38866篇 |
2011年 | 39763篇 |
2010年 | 27085篇 |
2009年 | 25080篇 |
2008年 | 35142篇 |
2007年 | 36550篇 |
2006年 | 34273篇 |
2005年 | 33357篇 |
2004年 | 33017篇 |
2003年 | 31572篇 |
2002年 | 30785篇 |
2001年 | 51953篇 |
2000年 | 51975篇 |
1999年 | 41708篇 |
1998年 | 15324篇 |
1997年 | 15552篇 |
1996年 | 14739篇 |
1995年 | 13722篇 |
1994年 | 13344篇 |
1993年 | 13333篇 |
1992年 | 34283篇 |
1991年 | 33651篇 |
1990年 | 32949篇 |
1989年 | 32174篇 |
1988年 | 29858篇 |
1987年 | 28593篇 |
1986年 | 26701篇 |
1985年 | 27084篇 |
1984年 | 22350篇 |
1983年 | 19362篇 |
1982年 | 14797篇 |
1981年 | 13640篇 |
1980年 | 12632篇 |
1979年 | 21234篇 |
1978年 | 16911篇 |
1977年 | 15402篇 |
1976年 | 14762篇 |
1975年 | 16476篇 |
1974年 | 17907篇 |
1973年 | 17820篇 |
1972年 | 16197篇 |
1971年 | 14654篇 |
1970年 | 12834篇 |
1969年 | 12513篇 |
1968年 | 11333篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
Sacramento Doralice Rodrigues Coelho Rosalie Reed Rodrigues Wigg Márcia Dutra Toledo Luna Linhares Luiz Fernando de Matos dos Santos Marta Gonçalves Azevedo Soares Semêdo Luzia Teixeira de Ribeiro da Silva Antonio Jorge 《World journal of microbiology & biotechnology》2004,20(3):225-229
A promising producer of bioactive compounds isolated from a Brazilian tropical soil was tested for its range of antimicrobial
activities. Strain 606, classified as Streptomyces sp., could not be identified up to species level, suggesting a possible new taxon. The supernatant and 10 extracts and fractions,
obtained by extraction and chromatographic techniques, presented antimicrobial activity using antibiograms. The methanolic
fraction was highly active against pathogenic bacteria, phytopathogenic fungi and the human pathogenic yeast Candida albicans. It also possessed high antiviral activity inhibiting the propagation of an acyclovir-resistant herpes simplex virus type
1 strain on HEp-2 cells at non-cytotoxic concentration. The strong cytotoxic effect suggests an antitumour action.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
72.
Formation of rings from Drosophila DNA fragments 总被引:1,自引:0,他引:1
73.
74.
Four myeloid cell lines (M1, WEHI-3B D+, FDC-P1, and 32D) were screened for the presence of J11d antigen. One of these cell lines, the myeloid leukemia M1, was found to express a high level of J11d antigen on the cell surface. Recombinant mouse leukemic inhibitory factor (rm-LIF), recombinant human LIF (rh-LIF), and steroids (hydrocortisone and dexamethasone) could induce M1 cells to undergo monocytic differentiation. The level of J11d antigen was greatly reduced after treatment of the cells with LIF or steroids. Western blotting revealed that the apparent molecular weight of the J11d antigen on M1 cells was 45-48 kDa. Furthermore, the level of J11d mRNA was also reduced during LIF-induced differentiation of M1 cells. 相似文献
75.
76.
77.
78.
79.
A. R. E. SINCLAIR 《African Journal of Ecology》1973,11(1):93-107
Censuses of buffalo and wildebeest in the Serengeti-Mara region have been carried out by various workers at intervals since 1958. The methods of these censuses, which normally employ a total count, are described and the errors inherent in such techniques are analysed in detail. After the appropriate corrections had been made the results showed that both populations have increased considerably over the years 1961–1971. 相似文献
80.