全文获取类型
收费全文 | 16030篇 |
免费 | 1305篇 |
国内免费 | 1134篇 |
出版年
2024年 | 10篇 |
2023年 | 195篇 |
2022年 | 257篇 |
2021年 | 854篇 |
2020年 | 568篇 |
2019年 | 760篇 |
2018年 | 758篇 |
2017年 | 558篇 |
2016年 | 786篇 |
2015年 | 1036篇 |
2014年 | 1287篇 |
2013年 | 1413篇 |
2012年 | 1506篇 |
2011年 | 1364篇 |
2010年 | 826篇 |
2009年 | 742篇 |
2008年 | 843篇 |
2007年 | 702篇 |
2006年 | 561篇 |
2005年 | 503篇 |
2004年 | 417篇 |
2003年 | 362篇 |
2002年 | 268篇 |
2001年 | 249篇 |
2000年 | 222篇 |
1999年 | 229篇 |
1998年 | 154篇 |
1997年 | 134篇 |
1996年 | 119篇 |
1995年 | 110篇 |
1994年 | 103篇 |
1993年 | 87篇 |
1992年 | 102篇 |
1991年 | 100篇 |
1990年 | 52篇 |
1989年 | 55篇 |
1988年 | 41篇 |
1987年 | 32篇 |
1986年 | 22篇 |
1985年 | 27篇 |
1984年 | 23篇 |
1983年 | 15篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Yao Shen Yueyang Tian Xiaojie Shi Jianbo Yang Li Ouyang Jieqiong Gao Jianxin Lu 《Cell biochemistry and function》2014,32(6):530-537
Astrocytes play a key role in removing the synaptically released glutamate from the extracellular space and maintaining the glutamate below neurotoxic level in the brain. However, high concentration of glutamate leads to toxicity in astrocytes, and the underlying mechanisms are unclear. The purpose of this study was to investigate whether energy metabolism disorder, especially impairment of mitochondrial respiration, is involved in the glutamate‐induced gliotoxicity. Exposure to 10‐mM glutamate for 48 h stimulated glycolysis and respiration in astrocytes. However, the increased oxygen consumption was used for proton leak and non‐mitochondrial respiration, but not for oxidative phosphorylation and ATP generation. When the exposure time extended to 72 h, glycolysis was still activated for ATP generation, but the mitochondrial ATP‐linked respiration of astrocytes was reduced. The glutamate‐induced astrocyte damage can be mimicked by the non‐metabolized substrate d ‐aspartate but reversed by the non‐selective glutamate transporter inhibitor TBOA. In addition, the glutamate toxicity can be partially reversed by vitamin E. These findings demonstrate that changes of bioenergetic profile occur in cultured cortical astrocytes exposed to high concentration of glutamate and highlight the role of mitochondria respiration in glutamate‐induced gliotoxicity in cortical astrocytes. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
3.
Chun Y. Gao Peggy S. Zelenka 《BioEssays : news and reviews in molecular, cellular and developmental biology》1997,19(4):307-315
Cyclin-dependent kinases and their regulatory subunits, the cyclins, are known to regulate progression through the cell cycle. Yet these same proteins are often expressed in non-cycling, differentiated cells. This review surveys the available information about cyclins and cyclin-dependent kinases in differentiated cells and explores the possibility that these proteins may have important functions that are independent of cell cycle regulation. 相似文献
4.
Jing Liu Dongxiao Gao Juhua Dan Dan Liu Lei Peng Ruoyu Zhou Ying Luo 《Journal of cellular biochemistry》2019,120(10):16408-16415
Aging process in mammals is associated with a decline in amplitude and a long period of circadian behaviors which are regulated by a central circadian regulator in the suprachiasmatic nucleus (SCN) and local oscillators in peripheral tissues. It is unclear whether enhancing clock function can retard aging. Using fibroblasts expressing per2::lucSV and senescent cells, we revealed cycloastragenol (CAG), a natural aglycone derivative from astragaloside IV, as a clock amplitude enhancing small molecule. CAG could activate telomerase to antiaging, but no reports focused on its effects on circadian rhythm disorders in aging mice. Here we analyze the potential effects of CAG on d -galactose-induced aging mice on the circadian behavior and expression of clock genes. For this purpose, CAG (20 mg/kg orally), was administered daily to d -galactose (150 mg/kg, subcutaneous) mice model of aging for 6 weeks. An actogram analysis of free-running activity of these mice showed that CAG significantly enhances the locomotor activity. We further found that CAG increase expressions of per2 and bmal1 genes in liver and kidney of aging mouse. Furthermore, CAG enhanced clock protein BMAL1 and PER2 levels in aging mouse liver and SCN. Our results indicated that the CAG could restore the behavior of circadian rhythm in aging mice induced by d -galactose. These data of present study suggested that CAG could be used as a novel therapeutic strategy for the treatment of age-related circadian rhythm disruption. 相似文献
5.
6.
7.
8.
Studies were conducted to determine the relationship between the pretherapy characteristics of leukemia cells and their behaviour during culture in vitro. Leukemia cells which proliferated well in vitro also proliferated well in vivo. Cells which manifested myeloid or monocytic differentiation in vivo tended to manifest differentiation along these lines in vitro. Cells which manifested high levels of expression of c-fms, c-fes, or triose phosphate isomerase prior to culture were likely to differentiate in vitro, with high levels of c-fes expression being related to myeloid maturation. These observations suggest that differentiation at the molecular level prior to culture is a requisite for leukemia cell differentiation in vitro. The same may be true for differentiation in vivo under the influence of exogenously administered agents such as cytotoxic chemotherapy or recombinant growth factors. 相似文献
9.
10.
The function of NS4B is incompletely understood. The aim of the study is to understand the influence of NS4B on anti-viral response. After cell line stably expressing NS4B established, the influence of IFN-alpha of different concentration on VSV was studied using plaque assay; cell expression profiling caused by NS4B was studied using DNA microarray, and the IFNGR1 fluorescence intensity was analyzed. Our data showed that HCV-NS4B could suppress immuno-associated gene expression, in particular, IFN-gamma receptor signal transduction-related genes. Taken together, NS4B could play some roles in HCV resistance to IFN therapy. 相似文献