全文获取类型
收费全文 | 16407篇 |
免费 | 41篇 |
国内免费 | 41篇 |
专业分类
系统科学 | 72篇 |
丛书文集 | 109篇 |
教育与普及 | 29篇 |
理论与方法论 | 66篇 |
现状及发展 | 5872篇 |
研究方法 | 779篇 |
综合类 | 9240篇 |
自然研究 | 322篇 |
出版年
2013年 | 189篇 |
2012年 | 243篇 |
2011年 | 578篇 |
2010年 | 106篇 |
2008年 | 270篇 |
2007年 | 340篇 |
2006年 | 348篇 |
2005年 | 329篇 |
2004年 | 308篇 |
2003年 | 286篇 |
2002年 | 302篇 |
2001年 | 691篇 |
2000年 | 675篇 |
1999年 | 371篇 |
1998年 | 50篇 |
1992年 | 340篇 |
1991年 | 274篇 |
1990年 | 298篇 |
1989年 | 316篇 |
1988年 | 286篇 |
1987年 | 269篇 |
1986年 | 291篇 |
1985年 | 312篇 |
1984年 | 275篇 |
1983年 | 248篇 |
1982年 | 205篇 |
1981年 | 188篇 |
1980年 | 214篇 |
1979年 | 507篇 |
1978年 | 392篇 |
1977年 | 370篇 |
1976年 | 302篇 |
1975年 | 348篇 |
1974年 | 500篇 |
1973年 | 380篇 |
1972年 | 386篇 |
1971年 | 496篇 |
1970年 | 610篇 |
1969年 | 414篇 |
1968年 | 454篇 |
1967年 | 378篇 |
1966年 | 386篇 |
1965年 | 261篇 |
1959年 | 135篇 |
1958年 | 225篇 |
1957年 | 162篇 |
1956年 | 115篇 |
1955年 | 115篇 |
1954年 | 111篇 |
1948年 | 89篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Radiation hybrid map of the mouse genome. 总被引:13,自引:0,他引:13
W J Van Etten R G Steen H Nguyen A B Castle D K Slonim B Ge C Nusbaum G D Schuler E S Lander T J Hudson 《Nature genetics》1999,22(4):384-387
Radiation hybrid (RH) maps are a useful tool for genome analysis, providing a direct method for localizing genes and anchoring physical maps and genomic sequence along chromosomes. The construction of a comprehensive RH map for the human genome has resulted in gene maps reflecting the location of more than 30,000 human genes. Here we report the first comprehensive RH map of the mouse genome. The map contains 2,486 loci screened against an RH panel of 93 cell lines. Most loci (93%) are simple sequence length polymorphisms (SSLPs) taken from the mouse genetic map, thereby providing direct integration between these two key maps. We performed RH mapping by a new and efficient approach in which we replaced traditional gel- or hybridization-based assays by a homogeneous 5'-nuclease assays involving a single common probe for all genetic markers. The map provides essentially complete connectivity and coverage across the genome, and good resolution for ordering loci, with 1 centiRay (cR) corresponding to an average of approximately 100 kb. The RH map, together with an accompanying World-Wide Web server, makes it possible for any investigator to rapidly localize sequences in the mouse genome. Together with the previously constructed genetic map and a YAC-based physical map reported in a companion paper, the fundamental maps required for mouse genomics are now available. 相似文献
992.
Postmitochondrial supernatants prepared from livers of mice, rats, rabbits, dogs, and monkeys metabolized 2,4-dinitrotulene. The pattern of metabolites was characterized in both sexes of the species examined. In addition, the pattern of metabolites was altered by varying incubation conditions and pretreating male rats with phenobarbital or SKF 525-A. 相似文献
993.
D C Mourelatos 《Experientia》1979,35(6):822-824
The SCE frequency induced by Thiotepa and the effect of this antineoplastic drug in combination with caffeine have been studied in cultures of human peripheral blood. Caffeine was found to enchance SCE and breakage frequencies induced by Thiotepa in human lymphocytes. 相似文献
994.
In humans, as well as in mice, fed on high carbohydrate diets, there was a significant sex difference in the plasma tirglycerides in that males had higher levels than females. This was mainly due to the difference in their removal rate of circulating triglycerides in the animals of both sexes. In mice, males had higher levels of liver triglycerides as well as higher rate of incorporation of U- 14C-glucose into liver triglycerides when compared to females. 相似文献
995.
Enumeration of different types of spermatogonia, following a single i.p. administration of different doses of ethyl methanesulfonate in mice, showed a survival of A1-A4 and in spermatogonia is markedly reduced due to cell killing while the remaining types of spermatogonia were affected marginally. The cell killing effect was dose-dependent, and replenishment of these cells was observed by the end of one cycle of the seminiferous epithelium comprising of 8.5 days. 相似文献
996.
The increase in methemoglobin reductase activity in human erythrocytes upon incubation with inosine, phosphate, pyruvate occurs only in the presence of methylene blue. No difference in activity of the methemoglobin reductases was observed between enzyme extracts of fresh cells and aged cells. 相似文献
997.
998.
3 experimentally distinct transverse relaxation components of the water in frog sciatic nerve are obtained by Carr-Purcell-Meiboom-Gill technique. The relative weights of these components: approximately 29%; approximately 50%; approximately 21% fit well with water compartments in this tissue as revealed by previous methods. 相似文献
999.
Binding of the antiprotease Trasylol to human peripheral blood lymphocytes and polymorphonuclear leucocytes (PMNs) was demonstrated at the ultrastructural level using an indirect immunoperoxidase technique. This also revealed endocytosis of membrane bound Trasylol by PMNs. Trasylol inhibited PHA- and ConA-induced lymphocyte stimulation, and was cytotoxic to unstimulated cells. 相似文献
1000.