全文获取类型
收费全文 | 25155篇 |
免费 | 1900篇 |
国内免费 | 10篇 |
出版年
2023年 | 122篇 |
2022年 | 270篇 |
2021年 | 615篇 |
2020年 | 373篇 |
2019年 | 500篇 |
2018年 | 627篇 |
2017年 | 506篇 |
2016年 | 864篇 |
2015年 | 1303篇 |
2014年 | 1425篇 |
2013年 | 1789篇 |
2012年 | 2089篇 |
2011年 | 2034篇 |
2010年 | 1258篇 |
2009年 | 1107篇 |
2008年 | 1498篇 |
2007年 | 1410篇 |
2006年 | 1287篇 |
2005年 | 1187篇 |
2004年 | 1074篇 |
2003年 | 1034篇 |
2002年 | 839篇 |
2001年 | 207篇 |
2000年 | 208篇 |
1999年 | 219篇 |
1998年 | 164篇 |
1997年 | 156篇 |
1996年 | 142篇 |
1995年 | 120篇 |
1994年 | 130篇 |
1993年 | 140篇 |
1992年 | 135篇 |
1991年 | 142篇 |
1990年 | 154篇 |
1989年 | 115篇 |
1988年 | 87篇 |
1987年 | 96篇 |
1986年 | 101篇 |
1985年 | 130篇 |
1984年 | 90篇 |
1983年 | 96篇 |
1982年 | 78篇 |
1981年 | 80篇 |
1980年 | 78篇 |
1979年 | 83篇 |
1978年 | 73篇 |
1977年 | 68篇 |
1975年 | 71篇 |
1974年 | 52篇 |
1973年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 703 毫秒
1.
2.
Sebastián Moran Miguel Vizoso Anna Martinez-Cardús Antonio Gomez Xavier Matías-Guiu Sebastián M Chiavenna Andrés G Fernandez Manel Esteller 《Epigenetics》2014,9(6):829-833
A formalin-fixed paraffin-embedded (FFPE) sample usually yields highly degraded DNA, which limits the use of techniques requiring high-quality DNA, such as Infinium Methylation microarrays. To overcome this restriction, we have applied an FFPE restoration procedure consisting of DNA repair and ligation processes in a set of paired fresh-frozen (FF) and FFPE samples. We validated the FFPE results in comparison with matched FF samples, enabling us to use FFPE samples on the Infinium HumanMethylation450 Methylation array. 相似文献
3.
C Johnston 《CMAJ》1992,146(8):1446-1447
4.
5.
Myoglobin (Mb) is the classic vertebrate oxygen-binding protein present in aerobic striated muscles. It functions principally in oxygen delivery and provides muscle with its characteristic red colour. Members of the Antarctic icefish family (Channichthyidae) are widely thought to be extraordinary for lacking cardiac Mb expression, a fact that has been attributed to their low metabolic rate and unusual evolutionary history. Here, we report that cardiac Mb deficit, associated with pale heart colour, has evolved repeatedly during teleost evolution. This trait affects both gill- and air-breathing species from temperate to tropical habitats across a full range of salinities. Cardiac Mb deficit results from total pseudogenization in three-spined stickleback and is associated with a massive reduction in mRNA level in two species that evidently retain functional Mb. The results suggest that near or complete absence of Mb-assisted oxygen delivery to heart muscle is a common facet of teleost biodiversity, even affecting lineages with notable oxygen demands. We suggest that Mb deficit may affect how different teleost species deal with increased tissue oxygen demands arising under climate change. 相似文献
6.
W W Johnston 《Acta cytologica》1984,28(3):218-224
From the time of its introduction, in 1973, through November 1983, fine needle aspiration biopsy ( FNAB ) of the lung was used in the diagnostic evaluation of 1,015 patients at the Duke University Medical Center and Durham Veterans Administration Medical Center. A diagnosis of a primary lung cancer was established in 49.4% of the cases and malignant neoplasm metastatic to the lung in 14.1%; a benign diagnosis was made in 31.1% and an inconclusive one in 5.4%. In 123 patients in whom lung tissue was also available, cancer was correctly diagnosed by FNAB in 83.8%, not diagnosed by FNAB in 14.6% and incorrectly diagnosed in 1.6%. In 37 patients without cancer, FNAB detected an infectious organism or a specific morphologic type of inflammation (abscess and granuloma). 相似文献
7.
8.
Abstract— 2-Hydroxy-, 2-chloro-, 2- and Cmethyl-GABA are linear competitive inhibitors of GABA uptake in rat brain slices. These analogues are thus potential substrates for the GABA transport system and possible'false transmitters'. 2-Hydroxy-GABA is the most potent inhibitor of GABA uptake yet described. No specific inhibitor of GABA uptake was revealed amongst the drugs tested. 相似文献
9.
10.