全文获取类型
收费全文 | 319419篇 |
免费 | 36783篇 |
国内免费 | 292篇 |
出版年
2018年 | 2867篇 |
2017年 | 2597篇 |
2016年 | 3653篇 |
2015年 | 4939篇 |
2014年 | 5879篇 |
2013年 | 8140篇 |
2012年 | 9228篇 |
2011年 | 9326篇 |
2010年 | 6245篇 |
2009年 | 5845篇 |
2008年 | 8344篇 |
2007年 | 8464篇 |
2006年 | 8318篇 |
2005年 | 7902篇 |
2004年 | 7802篇 |
2003年 | 7581篇 |
2002年 | 7478篇 |
2001年 | 18101篇 |
2000年 | 18215篇 |
1999年 | 14011篇 |
1998年 | 4214篇 |
1997年 | 4478篇 |
1996年 | 4120篇 |
1995年 | 3759篇 |
1994年 | 3673篇 |
1993年 | 3787篇 |
1992年 | 10857篇 |
1991年 | 10768篇 |
1990年 | 10227篇 |
1989年 | 10029篇 |
1988年 | 9301篇 |
1987年 | 8656篇 |
1986年 | 7855篇 |
1985年 | 7743篇 |
1984年 | 6132篇 |
1983年 | 5343篇 |
1982年 | 3808篇 |
1981年 | 3386篇 |
1980年 | 3220篇 |
1979年 | 5607篇 |
1978年 | 4336篇 |
1977年 | 3994篇 |
1976年 | 3530篇 |
1975年 | 4008篇 |
1974年 | 4175篇 |
1973年 | 4110篇 |
1972年 | 3594篇 |
1971年 | 3359篇 |
1970年 | 2972篇 |
1969年 | 2895篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
A linkage analysis of the murine Mos gene, which codes for the c-mos proto-oncogene, was performed in 88 backcross progeny of an interspecies cross of laboratory mice and Mus spretus. Linkage was tested for four different genes on mouse chromosome 4: Aco-1, Mup-1, b, and Ifb. The gene order (from centromere) with intervening percentage recombination is Mos-15.9 (+/- 3.9)-Aco-1-5.6 (+/- 2.4)-Mup-1-3.4 (+/- 1.9)-b-5.6 (+/- 2.4)-Ifb. These results confirm the previous assignment of Mos to chromosome 4 on the basis of segregation in somatic cell hybrids (D. Swan et al., 1982, J. Virol. 44: 752-754) and show furthermore that Mos and the Ifa/Ifb clusters are not tightly linked as a group of intronless genes, but are separated by a map distance of 30.6 +/- 4.9 recombination units. The linkage data obtained in the present study place Mos in a region compatible with the physical map (D. W. Threadgill and J. E. Womack, 1988, Genomics 3: 82-86). 相似文献
992.
The effects of phorbol ester on mouse blastomeres: a role for protein kinase C in compaction? 总被引:1,自引:0,他引:1
T L Bloom 《Development (Cambridge, England)》1989,106(1):159-171
The effects of phorbol myristate acetate (PMA) and other activators of protein kinase C on the cytoskeletal organization of mouse oocytes and early embryos have been examined. The effects observed depended on the developmental stage on exposure to PMA. PMA had little effect on the cytoskeletal or microvillous organization of unfertilized oocytes. Interphase cells from embryos prior to compaction showed limited disruption and loss of microvilli when exposed to PMA and foci of polymerized actin remained visible in the cytocortex of embryos up to the early 8-cell stage. When compacted late 8-cell embryos were exposed to PMA, most microvilli were lost and little polymerized actin remained in the cytocortex. PMA also caused loss of microtubules from compact 8-cell embryos under some experimental conditions. Intercellular flattening was both prevented and reversed. The relevance of these observations to the rearrangement of cell-cell contacts and cytoskeletal organization seen during compaction at the 8-cell stage is discussed and a possible role for protein kinase C in the generation of cell polarity proposed. 相似文献
993.
994.
995.
996.
997.
Intermittent illumination increased H2 and C2H4 yields per unit of light from growing cells and from nitrogren-starved cells by 1.7- and 1.35-fold, respectively, as compared with continuous illumination. 相似文献
998.
Interactions of Abscisic Acid, Cytokinin and Gibberellin in the Control of Betacyanin Synthesis in Seedlings of Amaranthus caudatus 总被引:2,自引:0,他引:2
In de-rooted seedlings of Amaranthus caudatus L., betacyanin synthesis induced by white light or cytokinin was inhibited by abscisic acid (ABA) or a mixture of gibberellins A4 and A7 (GA4/7). The GA4/7 and ABA effects were additive. Thus ABA inhibited the cytokinin action but had no effect on the gibberellin response. 相似文献
999.
Since deaths of waterfowls have frequently been observed in Lake Kahoku near Kanazawa city, Japan, we attempted an ecological study on Clostridium botulinum type C in four other lakes as well as Lake Kahoku. One hundred and twenty-nine (56%) of 230 soil samples collected gave rise to lethal toxicity in mice with the characteristic “wasp-waist” symptom. All of the 51 samples arbitrarily selected were neutralized by C. botulinum type C antitoxic serum. A further seasonal study throughout the year at a given shore area of Lake Kahoku disclosed that nearly all samples gave rise to toxicity due to C. botulinum type C during the autumn season when the most waterfowls congregate. Toxigenic strains of C. botulinum type C were isolated together with nontoxigenic strains that were culturally and biochemically similar to the toxigenic strains. Both the toxigenic and nontoxigenic strains were equally agglutinable by an antiserum prepared against one of the nontoxigenic strains. Further extensive studies on the specificity of the agglutination method for identification were performed with 112 strains of 46 clostridial species. None of the strains used except some strains of C. novyi type A and a strain of C. botulinum type D was agglutinable. Based on the findings for cultural, biochemical, and agglutinable properties, the nontoxigenic strains were identified as C. botulinum type C. Also, C. novyi type A isolates showing colonies covered with a small pearly layer zone but surrounded by an aberrantly wide lecithinase zone are discussed. 相似文献
1000.