全文获取类型
收费全文 | 87145篇 |
免费 | 2287篇 |
国内免费 | 50篇 |
出版年
2018年 | 1034篇 |
2017年 | 1201篇 |
2016年 | 2959篇 |
2015年 | 6307篇 |
2014年 | 5935篇 |
2013年 | 5753篇 |
2012年 | 5019篇 |
2011年 | 2269篇 |
2010年 | 2219篇 |
2009年 | 2173篇 |
2008年 | 710篇 |
2007年 | 675篇 |
2006年 | 690篇 |
2005年 | 6753篇 |
2004年 | 5443篇 |
2003年 | 3644篇 |
2002年 | 1192篇 |
2001年 | 1118篇 |
2000年 | 382篇 |
1999年 | 1536篇 |
1998年 | 363篇 |
1997年 | 193篇 |
1992年 | 1949篇 |
1991年 | 2035篇 |
1990年 | 2088篇 |
1989年 | 2017篇 |
1988年 | 1974篇 |
1987年 | 1831篇 |
1986年 | 1635篇 |
1985年 | 1669篇 |
1984年 | 1113篇 |
1983年 | 851篇 |
1982年 | 485篇 |
1981年 | 437篇 |
1980年 | 392篇 |
1979年 | 1092篇 |
1978年 | 775篇 |
1977年 | 635篇 |
1976年 | 654篇 |
1975年 | 890篇 |
1974年 | 1001篇 |
1973年 | 1013篇 |
1972年 | 957篇 |
1971年 | 933篇 |
1970年 | 824篇 |
1969年 | 838篇 |
1968年 | 741篇 |
1967年 | 756篇 |
1966年 | 587篇 |
1965年 | 438篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Shells of the bivalve Arctica islandica are used to reconstruct paleo-environmental conditions (e.g. temperature) via biogeochemical proxies, i.e. biogenic components that are related closely to environmental parameters at the time of shell formation. Several studies have shown that proxies like element and isotope-ratios can be affected by shell growth and microstructure. Thus it is essential to evaluate the impact of changing environmental parameters such as high pCO2 and consequent changes in carbonate chemistry on shell properties to validate these biogeochemical proxies for a wider range of environmental conditions. Growth experiments with Arctica islandica from the Western Baltic Sea kept under different pCO2 levels (from 380 to 1120 µatm) indicate no affect of elevated pCO2 on shell growth or crystal microstructure, indicating that A. islandica shows an adaptation to a wider range of pCO2 levels than reported for other species. Accordingly, proxy information derived from A. islandica shells of this region contains no pCO2 related bias. 相似文献
83.
Protoplasts of Schizosaccharomyces pombe, grown on a rich nutrient medium, were treated with a peptide factor isolated from cultures of the protozoan Tetrahymena pyriformis. The peptide factor is known to inhibit RNA synthesis in Tetrahymena. It has now been shown that the peptide factor also inhibits RNA synthesis in yeast protoplasts without affecting protein synthesis. 相似文献
84.
85.
86.
87.
88.
The cytotoxic and radiosensitizing effects of hyperthermia was shown on Ehrlich ascites tumor cells heated in vitro. The effect of hyperthermia resulted in the formation of local lesions in membranes of dying cells. 相似文献
89.
H Zitzer H H H?nck D B?chner D Richter H J Kreienkamp 《The Journal of biological chemistry》1999,274(46):32997-33001
By using the yeast two-hybrid system we identified a novel protein from the human brain interacting with the C terminus of somatostatin receptor subtype 2. This protein termed somatostatin receptor interacting protein is characterized by a novel domain structure, consisting of six N-terminal ankyrin repeats followed by SH3 and PDZ domains, several proline-rich regions, and a C-terminal sterile alpha motif. It consists of 2185 amino acid residues encoded by a 9-kilobase pair mRNA; several splice variants have been detected in human and rat cDNA libraries. Sequence comparison suggests that the novel multidomain protein, together with cortactin-binding protein, forms a family of cytoskeletal anchoring proteins. Fractionation of rat brain membranes indicated that somatostatin receptor interacting protein is enriched in the postsynaptic density fraction. The interaction of somatostatin receptor subtype 2 with its interacting protein was verified by overlay assays and coimmunoprecipitation experiments from transfected human embryonic kidney cells. Somatostatin receptor subtype 2 and the interacting protein display a striking overlap of their expression patterns in the rat brain. Interestingly, in the hippocampus the mRNA for somatostatin receptor interacting protein was not confined to the cell bodies but was also observed in the molecular layer, suggesting a dendritic localization of this mRNA. 相似文献
90.