首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   898篇
  免费   43篇
  国内免费   98篇
  1039篇
  2024年   3篇
  2023年   20篇
  2022年   27篇
  2021年   52篇
  2020年   39篇
  2019年   69篇
  2018年   51篇
  2017年   18篇
  2016年   24篇
  2015年   30篇
  2014年   50篇
  2013年   73篇
  2012年   37篇
  2011年   39篇
  2010年   29篇
  2009年   33篇
  2008年   38篇
  2007年   39篇
  2006年   31篇
  2005年   36篇
  2004年   23篇
  2003年   24篇
  2002年   17篇
  2001年   17篇
  2000年   24篇
  1999年   19篇
  1998年   17篇
  1997年   18篇
  1996年   8篇
  1995年   10篇
  1994年   10篇
  1993年   9篇
  1992年   10篇
  1991年   14篇
  1990年   6篇
  1989年   8篇
  1988年   9篇
  1987年   4篇
  1986年   7篇
  1985年   6篇
  1984年   7篇
  1983年   6篇
  1982年   5篇
  1981年   5篇
  1980年   2篇
  1979年   4篇
  1978年   3篇
  1977年   2篇
  1973年   3篇
  1972年   1篇
排序方式: 共有1039条查询结果,搜索用时 0 毫秒
991.
《Cell Stem Cell》2021,28(10):1790-1804.e8
  1. Download : Download high-res image (153KB)
  2. Download : Download full-size image
  相似文献   
992.
993.
Pituitary β-endorphin content was measured in dormice during several distinct phases of the infradian body weight cycle. No significant differences in opiate content among groups were found. It appears unlikely that pituitary concentrations of β-endorphin have etiological significance in the development of spontaneous obesity in hibernators.  相似文献   
994.
Abnormal long non-coding RNAs (lncRNAs) have been detected in esophageal squamous cell carcinoma (ESCC). Here, we focused on lncRNA ZNF667-AS1 and its downstream mechanism in ESCC progression. Differentially expressed lncRNAs in ESCC were predicted by bioinformatics analysis. ZNF667-AS1, microRNA-1290 (miR-1290), and prune homolog 2 with BCH domain (PRUNE2) expression was determined with their relationship in cell biological processes analyzed also by means of gain- and loss-of-function assays. Xenograft mouse models were performed to re-produce the in vitro findings. We found a decline in ZNF667-AS1 expression in ESCC tissues and cell lines. ZNF667-AS1 overexpression indicated a favorable prognosis of ESCC sufferers. ZNF667-AS1 overexpression suppressed ESCC cell malignant potentials. ZNF667-AS1 reduced miR-1290 to result in upregulation of the miR-1290 target gene PRUNE2. The inhibiting property of ZNF667-AS1 on the malignant characteristics of ESCC cells was achieved by disrupting the miR-1290-mediated downregulation of PRUNE2. ZNF667-AS1 suppressed the tumorigenesis of ESCC in vivo. Collectively, our study demonstrates that ZNF667-AS1 can function as a tumor suppressor in ESCC by upregulating PRUNE2 and downregulating miR-1290.  相似文献   
995.
Previously, we have demonstrated the effects of exogenously administered opiates on somatostatin release in dogs and therefore the present study was designed to determine the effect of endogenous opiates via naloxone-induced opiate receptor blockade on somatostatin release. Additionally, plasma insulin and pancreatic polypeptide (PP) levels were determined in response to intragastrically instilled protein, carbohydrate and fat test meals in a group of eight conscious dogs. To all test meals either naloxone (4 mg) or saline was added. The rise of plasma somatostatin levels in response to liver extract, sucrose and fat was attenuated significantly by naloxone. Naloxone had no effect on the rise of postprandial plasma insulin and PP levels. The present data demonstrate that endogenous opiates have a stimulatory effect on postprandial somatostatin release in dogs which indicates a tight interaction that might be of relevance for nutrient homeostasis.  相似文献   
996.
997.
Nitrogen balances (six days) were determined in male Wistar rats during feeding a diet with sufficient protein or a nearly protein-free diet (n = 2×24), and then during three days of starvation (n = 2×12). The objective was to evaluate the effect of protein withdrawal on minimum nitrogen excretion in urine (UN), corresponding to endogenous UN, during feeding and subsequent starvation periods. The rats fed the protein free-diet had almost the same excretion of urinary N during feeding and starvation (165 and 157 mg/kg W0.75), while it was 444 mg/kg W0.75 in rats previously fed with protein, demonstrating a major influence of protein content in a diet on Nexcretion during starvation. Consequently, the impact of former protein supply on Nlosses during starvation ought to be considered when evaluating minimum N requirement necessary to sustain life.  相似文献   
998.
This paper examines the sensitivity of endogenous bursters to a brief input pulse. The interneurons of the lobster cardiac ganglion were selected as a case study.Using a mathematical model specifically developed for the neurons in the cardiac ganglion of the lobster (Av-Ron et al., 1993), we show a tight link between burst characteristics and certain other parameters. We show that cells with different burst properties differ in their sensitivity to an input of a brief pulse.Irrespective of these differences, all cells display a bimodal response to a brief pulse applied during the quiescent period. During the first three-quarters of the quiescent period, they respond by producing a single spike at most. During the remaining one-quarter, the brief pulse can initiate the cells' intrinsic burst. Our predictions fit experimental results obtained by Tazaki and Cooke (1979).The results obtained herein are discussed with respect to fault tolerance considerations.  相似文献   
999.
《Cell》2023,186(2):413-427.e17
  1. Download : Download high-res image (301KB)
  2. Download : Download full-size image
  相似文献   
1000.
《Cell Stem Cell》2021,28(9):1566-1581.e8
  1. Download : Download high-res image (176KB)
  2. Download : Download full-size image
  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号