全文获取类型
收费全文 | 540篇 |
免费 | 66篇 |
专业分类
606篇 |
出版年
2022年 | 3篇 |
2021年 | 5篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 11篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 21篇 |
2014年 | 19篇 |
2013年 | 25篇 |
2012年 | 27篇 |
2011年 | 36篇 |
2010年 | 20篇 |
2009年 | 26篇 |
2008年 | 19篇 |
2007年 | 15篇 |
2006年 | 17篇 |
2005年 | 24篇 |
2004年 | 23篇 |
2003年 | 12篇 |
2002年 | 25篇 |
2001年 | 23篇 |
2000年 | 28篇 |
1999年 | 19篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1996年 | 4篇 |
1995年 | 8篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 13篇 |
1991年 | 12篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1988年 | 17篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 8篇 |
1984年 | 3篇 |
1982年 | 4篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1974年 | 2篇 |
1971年 | 2篇 |
1970年 | 2篇 |
1969年 | 8篇 |
1967年 | 2篇 |
1930年 | 3篇 |
1928年 | 4篇 |
1926年 | 3篇 |
排序方式: 共有606条查询结果,搜索用时 0 毫秒
601.
Having a working draft of the human genome sequence is proving invaluable to mouse genetic and genomic studies, providing a useful stepping-stone towards the finished sequence of the mouse genome. 相似文献
602.
603.
Alfred E. Asato Bao-Wen Zhang Marlene Denny Taraneh Mirzadegan Karl Seff Robert S. H. Liu 《Bioorganic chemistry》1989,17(4)
Results of the binding interaction of isomers of α-retinal and six substituted α-retinals (5-butyl, 5-phenyl, 5-isopropyl, 5-heptyl, 5-decyl, and 10-fluoro) with bovine opsin are reported. Their implications on the binding site requirements are discussed. 相似文献
604.
605.
Patricia A. Denny Watchara Pimprapaiporn Maureen S. Kim Dr. Paul C. Denny 《Cell and tissue research》1988,251(2):381-386
Summary In this study, antiserum to acinar cell-specific mucin was utilized to determine whether mucin could be detected in the mouse submandibular gland prior to cytodifferentiation of acinar cells. Results from radioimmunoassay indicated that mucin occurs in submandibular glands from newborn mice, i.e., before the appearance of mature acinar cells. Additionally, mucin quantitated in various stages of development was found to be antigenically identical to adult mucin. After sections of glands were treated with immunohistochemical reagents, we observed that the mature acinar cell-specific mucin was present in secretory terminal-tubule cells and in proacinar cells of newborn animals. The present findings suggest that in young animals, the proacinar cells are an immediate precursor of acinar cells and that the secretory terminal-tubule cells may represent an earlier stage in development of acinar cells. In adult female glands, mucin was also detected in the granular intercalating-duct cells. This latter observation is consistent with the hypothesis that these cells are an intermediate in the acinar cell replacement process. 相似文献
606.
Radiosensitization of mammalian cells in vitro by nitroacridines 总被引:1,自引:0,他引:1
The nitroacridine nitracrine (1-NC) is a DNA intercalator and a hypoxia-selective, electron-affinic radiosensitizer. Sensitization of Chinese hamster fibroblast cultures at 0 degrees C by the nitro positional isomers of 1-NC has now been compared to help establish structure-activity relationships. The des-nitro analog (E(1) at pH 7 = -899 mV) did not sensitize, suggesting that an electron-affinic chromophore is required. All the nitroacridines (E(1) range -376 to -257 mV) sensitized hypoxic cells with a maximum sensitizer enhancement ratio of about 1.7, but with a 200-fold range in potency. When mean intracellular drug concentrations were compared, 2-, 3-, and 4-NC had potencies which were similar, independent of E(1), and no greater than predicted for non-DNA binding nitroheterocycles. Sensitization by these three isomers occurred at intracellular concentrations likely to saturate the potential intercalation sites on DNA. A large fraction of the radical sites sensitized by O2 are apparently inaccessible to these drugs. It is suggested that sensitization results from electron transfer from migrating transient charge carriers of low reduction potential to immobile bound intercalators. An additional sensitizing mechanism may be available to 1-NC, which was 20 times more potent, a potency not accounted for by E(1), cell uptake, or DNA binding affinity. The dissociation kinetics of the DNA-drug complex was faster for 1-NC than for the other isomers. The higher potency of 1-NC may reflect a short mean residence time (less than 1 ms) in its intercalation site, allowing significant mobility on the DNA within the lifetime of relatively stable radiation-induced target radicals. 相似文献