全文获取类型
收费全文 | 15191篇 |
免费 | 1316篇 |
国内免费 | 1811篇 |
出版年
2024年 | 57篇 |
2023年 | 258篇 |
2022年 | 594篇 |
2021年 | 892篇 |
2020年 | 634篇 |
2019年 | 782篇 |
2018年 | 671篇 |
2017年 | 522篇 |
2016年 | 687篇 |
2015年 | 1019篇 |
2014年 | 1161篇 |
2013年 | 1207篇 |
2012年 | 1437篇 |
2011年 | 1278篇 |
2010年 | 757篇 |
2009年 | 679篇 |
2008年 | 843篇 |
2007年 | 651篇 |
2006年 | 589篇 |
2005年 | 543篇 |
2004年 | 473篇 |
2003年 | 386篇 |
2002年 | 342篇 |
2001年 | 285篇 |
2000年 | 241篇 |
1999年 | 221篇 |
1998年 | 159篇 |
1997年 | 134篇 |
1996年 | 107篇 |
1995年 | 127篇 |
1994年 | 86篇 |
1993年 | 70篇 |
1992年 | 76篇 |
1991年 | 66篇 |
1990年 | 56篇 |
1989年 | 55篇 |
1988年 | 36篇 |
1987年 | 34篇 |
1986年 | 23篇 |
1985年 | 27篇 |
1984年 | 18篇 |
1983年 | 18篇 |
1982年 | 9篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1959年 | 1篇 |
1950年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
11.
12.
13.
14.
Background
Many molecules are flexible and undergo significant shape deformation as part of their function, and yet most existing molecular shape comparison (MSC) methods treat them as rigid bodies, which may lead to incorrect shape recognition. 相似文献15.
After observing specimens of Calligonum pumilum Losinsk. and C. juochiangense Y. X. Liou in both the field and in herbarium collections, it was found that the morphological characters of these two species are quite different, especially with respect of the twisted direction of fruit ribs, number of bristle rows along each rib, rigidity and degree of interweaving of bristles, as well as their geographic distribution. Therefore, it is concluded that C. pumilum and C. juochiangense should be accepted as two independent species. 相似文献
16.
Theofilos Poutahidis Sean M. Kearney Tatiana Levkovich Peimin Qi Bernard J. Varian Jessica R. Lakritz Yassin M. Ibrahim Antonis Chatzigiagkos Eric J. Alm Susan E. Erdman 《PloS one》2013,8(10)
Wound healing capability is inextricably linked with diverse aspects of physical fitness ranging from recovery after minor injuries and surgery to diabetes and some types of cancer. Impact of the microbiome upon the mammalian wound healing process is poorly understood. We discover that supplementing the gut microbiome with lactic acid microbes in drinking water accelerates the wound-healing process to occur in half the time required for matched control animals. Further, we find that Lactobacillus reuteri enhances wound-healing properties through up-regulation of the neuropeptide hormone oxytocin, a factor integral in social bonding and reproduction, by a vagus nerve-mediated pathway. Bacteria-triggered oxytocin serves to activate host CD4+Foxp3+CD25+ immune T regulatory cells conveying transplantable wound healing capacity to naive Rag2-deficient animals. This study determined oxytocin to be a novel component of a multi-directional gut microbe-brain-immune axis, with wound-healing capability as a previously unrecognized output of this axis. We also provide experimental evidence to support long-standing medical traditions associating diet, social practices, and the immune system with efficient recovery after injury, sustained good health, and longevity. 相似文献
17.
18.
19.
Pluripotent stem cells (PSCs) are cells that can differentiate into any type of cells in the body, therefore have valuable promise in regenerative medicine of cell replacement therapies and tissue/organ engineering. PSCs can be derived either from early embryos or directly from somatic cells by epigenetic reprogramming that result in customized cells from patients. Here we summarize the methods of deriving PSCs, the various types of PSCs generated with different status, and their versatile applications in both clinical and embryonic development studies. We also discuss an intriguing potential application of PSCs in constructing tissues/organs in large animals by interspecies chimerism. All these emerging findings are likely to contribute to the breakthroughs in biological research and the prosperous prospects of regenerative medicine. 相似文献
20.
Isoelectric focusing in immobilized pH gradients of a snake venom fibrinolytic enzyme 总被引:1,自引:0,他引:1
A fibrinolytic enzyme with a molecular weight between 23,000 and 25,000 Da has been purified from southern copperhead snake venom. Immobilized pH gradient isoelectric focusing with an ultranarrow pH interval (pH 6.65-6.95) resolved two isoforms of the fibrinolytic enzyme that were not resolved by standard isoelectric focusing. Attempts at purification of the individual isoenzymes by semi-preparative scale IPG and elution of enzyme by macerating the gel yielded only 20-40% recovery of activity. In attempts to improve recovery, a semi-preparative IPG canal-isoelectric focusing technique has been utilized. 相似文献