全文获取类型
收费全文 | 32087篇 |
免费 | 2470篇 |
国内免费 | 1614篇 |
出版年
2024年 | 66篇 |
2023年 | 357篇 |
2022年 | 858篇 |
2021年 | 1443篇 |
2020年 | 996篇 |
2019年 | 1241篇 |
2018年 | 1239篇 |
2017年 | 880篇 |
2016年 | 1302篇 |
2015年 | 2046篇 |
2014年 | 2281篇 |
2013年 | 2464篇 |
2012年 | 2835篇 |
2011年 | 2489篇 |
2010年 | 1577篇 |
2009年 | 1352篇 |
2008年 | 1637篇 |
2007年 | 1442篇 |
2006年 | 1301篇 |
2005年 | 1115篇 |
2004年 | 916篇 |
2003年 | 811篇 |
2002年 | 621篇 |
2001年 | 570篇 |
2000年 | 471篇 |
1999年 | 471篇 |
1998年 | 276篇 |
1997年 | 295篇 |
1996年 | 283篇 |
1995年 | 223篇 |
1994年 | 239篇 |
1993年 | 161篇 |
1992年 | 259篇 |
1991年 | 230篇 |
1990年 | 166篇 |
1989年 | 141篇 |
1988年 | 110篇 |
1987年 | 142篇 |
1986年 | 110篇 |
1985年 | 87篇 |
1984年 | 82篇 |
1983年 | 68篇 |
1982年 | 60篇 |
1981年 | 43篇 |
1980年 | 35篇 |
1979年 | 43篇 |
1978年 | 40篇 |
1977年 | 32篇 |
1975年 | 34篇 |
1974年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Yang Su-Rong Sun Huan-Xin Hu Zhen-Zhen Wang Si-Heng Sun Hui Xue Yin-Jia Ye Chen-Bo 《Sleep and biological rhythms》2017,15(1):57-65
Sleep and Biological Rhythms - Chronic sleep deprivation (SD) is an overwhelming problem in young students. Firstly, we investigated whether different levels of pre-training SD had effects on... 相似文献
12.
Splenic gene expression profiling in White Leghorn layer inoculated with the Salmonella enterica serovar Enteritidis 下载免费PDF全文
Salmonella enterica serovar Enteritidis (SE) is a foodborne pathogen that can threaten human health through contaminated poultry products. Live poultry, chicken eggs and meat are primary sources of human salmonellosis. To understand the genetic resistance of egg‐type chickens in response to SE inoculation, global gene expression in the spleen of 20‐week‐old White Leghorn was measured using the Agilent 4 × 44 K chicken microarray at 7 and 14 days following SE inoculation (dpi). Results showed that there were 1363 genes significantly differentially expressed between inoculated and non‐inoculated groups at 7 dpi (I7/N7), of which 682 were up‐regulated and 681 were down‐regulated genes. By contrast, 688 differentially expressed genes were observed at 14 dpi (I14/N14), of which 371 were up‐regulated genes and 317 were down‐regulated genes. There were 33 and 28 immune‐related genes significantly differentially expressed in the comparisons of I7/N7 and I14/N14 respectively. Functional annotation revealed that several Gene Ontology (GO) terms related to immunity were significantly enriched between the inoculated and non‐inoculated groups at 14 dpi but not at 7 dpi, despite a similar number of immune‐related genes identified between I7/N7 and I14/N14. The immune response to SE inoculation changes with different time points following SE inoculation. The complicated interaction between the immune system and metabolism contributes to the immune responses to SE inoculation of egg‐type chickens at 14 dpi at the onset of lay. GC, TNFSF8, CD86, CD274, BLB1 and BLB2 play important roles in response to SE inoculation. The results from this study will deepen the current understanding of the genetic response of the egg‐type chicken to SE inoculation at the onset of egg laying. 相似文献
13.
The accumulation of gentamicin by rat renal cortex and was not inhibited by probenecid, tetraethylammonium, cephalosporins nor α-aminoisobutyric acid, but was significantly blocked by other aminoglycosides (neomycin, tobramycin and kanamycin). The data suggest that specific binding sites for aminoglycosides are present on the surface or in cells of the renal proximal tubule. 相似文献
14.
15.
16.
17.
Mengmeng Zhuang Yuequ Deng Wenwen Zhang Bo Zhu Hao Yan Jiaqi Lou Pan Zhang Qingwei Cui Hao Tang Han Sun Yong Sun 《Cell death & disease》2021,12(6)
Intestinal mucosal injuries are directly or indirectly related to many common acute and chronic diseases. Long non-coding RNAs (lncRNAs) are expressed in many diseases, including intestinal mucosal injury. However, the relationship between lncRNAs and intestinal mucosal injury has not been determined. Here, we investigated the functions and mechanisms of action of lncRNA Bmp1 on damaged intestinal mucosa. We found that Bmp1 was increased in damaged intestinal mucosal tissue and Bmp1 overexpression was able to alleviate intestinal mucosal injury. Bmp1 overexpression was found to influence cell proliferation, colony formation, and migration in IEC-6 or HIEC-6 cells. Moreover, miR-128-3p was downregulated after Bmp1 overexpression, and upregulation of miR-128-3p reversed the effects of Bmp1 overexpression in IEC-6 cells. Phf6 was observed to be a target of miR-128-3p. Furthermore, PHF6 overexpression affected IEC-6 cells by activating PI3K/AKT signaling which was mediated by the miR-128-3p/PHF6 axis. In conclusion, Bmp1 was found to promote the expression of PHF6 through the sponge miR-128-3p, activating the PI3K/AKT signaling pathway to promote cell migration and proliferation.Subject terms: Cell growth, Cell migration 相似文献
18.
J.C. Kuo Edward S. Yeung 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1982,229(2)
A separation and detection scheme is presented for the determination of free, esterified and total cholesterol in human serum. Separation is accomplished by reversed-phase high-performance liquid chromatography and the eluate is monitored by the laser-based optical activity detector. The method is simple, accurate and has the advantage of specificity and selectivity when compared with the many methods commonly used. 相似文献
19.
20.
Structural changes associated with corolla wilting may serve as a mechanism for effecting self-pollination. Low pollinator visitation, high seed production and a corolla that persists after anthesis indicates that Pedicularis dunniana is autogamous. Delayed autonomous self-pollination is facilitated by corolla wilting. Wilting of the upper lip (galea) brought the pollen laden anthers into contact with the stigma resulting in the deposition of self pollen on the stigma. The seed set of flowers either emasculated, or with restrained galeae thus preventing anthers brushing against the stigma, was significantly lower than that of open-pollinated flowers. This demonstrates that autogamy occurs in this species through corolla wilting. Germination experiments indicated that outcross seedlings were more vigorous than selfed seedlings as a result of inbreeding depression. It is likely that autogamy provides reproductive assurance for P. dunniana under conditions of pollinator scarcity. 相似文献