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   20232篇
  免费   1719篇
  国内免费   2036篇
  2024年   68篇
  2023年   304篇
  2022年   711篇
  2021年   1046篇
  2020年   776篇
  2019年   948篇
  2018年   956篇
  2017年   626篇
  2016年   888篇
  2015年   1300篇
  2014年   1553篇
  2013年   1621篇
  2012年   1942篇
  2011年   1743篇
  2010年   1061篇
  2009年   877篇
  2008年   1097篇
  2007年   881篇
  2006年   791篇
  2005年   692篇
  2004年   607篇
  2003年   559篇
  2002年   431篇
  2001年   309篇
  2000年   256篇
  1999年   312篇
  1998年   180篇
  1997年   163篇
  1996年   117篇
  1995年   123篇
  1994年   111篇
  1993年   87篇
  1992年   109篇
  1991年   92篇
  1990年   75篇
  1989年   61篇
  1988年   60篇
  1987年   38篇
  1986年   54篇
  1985年   43篇
  1984年   34篇
  1983年   25篇
  1982年   17篇
  1981年   15篇
  1979年   13篇
  1974年   12篇
  1973年   21篇
  1972年   12篇
  1966年   12篇
  1958年   13篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
HOXB13 exerts a close relation in several human cancers. This study explored the role of HOXB13 in glioblastoma (GBM), a brain tissue with the highest aggressive rate and mortality in adults. Through microarray and immunohistochemistry analyses, HOXB13 was highly expressed in GBM tissues. Furthermore, we showed that high-level expression of HOXB13 in GBM was associated with worse survival, suggesting that HOXB13 could be a prognostic marker for patients with GBM. GBM cells U87 and U251 overexpressing HOXB13 showed enhanced proliferation, migration, and invasion relative to the control cells, while knockdown of HOXB13 led to decreased cell proliferation, migration, and invasion abilities. In addition, dual-luciferase report assay, chromatin immunoprecipitation assay, and quantitative real-time polymerase chain reaction data showed that HOXB13 directly bound to HOXC-AS3 promoter. HOXC-AS3 was involved in HOXB13-induced proliferation, migration, and invasion of GBM cells. In summary, this study revealed the prognostic potential of HOXB13 in GBM. We believed that HOXB13/HOXC-AS3 signaling axis can be served as therapeutic targets for this highly aggressive cancer.  相似文献   
973.
974.
Endothelial cells (ECs) released microvesicles (EMVs) could modulate the functions of target cells by transferring their microRNAs (miRs). We have reported that miR-125a-5p protected EC function. In this study, we determined whether EMVs provided beneficial effects on ECs by transferring miR-125a-5p. Human brain microvessel ECs were transfected with miR-125a-5p mimic or miR-125a-5p short hairpin RNA to obtain miR-125a-5p overexpressing ECs and miR-125a-5p knockdown ECs, and their derived EMVs. For the functional study, ECs or hypoxia/reoxygenation injured ECs were coincubated with various EMVs. The survival and angiogenic function of ECs were measured. Western blot and quantitative real time polymerase chain reaction (qRT-PCR) were used for measuring the levels of phosphoinositide 3-kinase (PI3K), phosphorylation-Akt (p-Akt)/Akt, p-endothelial nitric oxide synthase (p-eNOS), cleaved caspase-3, and miR-125a-5p. PI3K inhibitor was used for pathway analysis. EMVs promoted the proliferation, migration, and tube formation ability of ECs, and alleviated the apoptotic rate of ECs. These effects were associated by an increase in p-Akt/Akt and p-eNOS, and a decrease in cleaved caspase-3 could be abolished by LY294002. Overexpression or downregulation of miR-125a-5p in EMVs promoted or inhibited those effects of EMVs. EMVs could enhance the survival and angiogenic function of ECs via delivering miR-125a-5p to modulate the expression of PI3K/Akt/eNOS pathway and caspase-3.  相似文献   
975.
Ribosomal protein L34 (RPL34), belonging to the L34E family of ribosomal proteins, was reported to be dysregulated in several types of cancers and plays important roles in tumor progression. However, the expression and roles of RPL34 in human glioma remain largely unknown. Thus, the objective of this study was to investigate the expression and role of RPL34 in glioma. We report here that RPL34 is highly expressed in human glioma tissues and cell lines. Knockdown of RPL34 markedly inhibited the proliferation, migration, and invasion, as well as prevented the epithelial-mesenchymal transition phenotype in glioma cells. Further, mechanistic analysis showed that knockdown of RPL34 significantly downregulated the levels of p-JAK and p-STAT3 in glioma cells. Taken together, our findings indicated that knockdown of RPL34 inhibits the proliferation and migration of glioma cells through the inactivation of JAK/STAT3 signaling pathway. Thus, RPL34 may serve as a potential therapeutic target for the treatment of glioma.  相似文献   
976.
977.
978.
In aquaculture, feeding is essential for the maintenance of metabolic processes and homoeostasis of fish. However, fasting acts as a stressor. In this study, we investigated the effect of circadian rhythm under various LED wavelengths [blue (460 nm), green (520 nm) and red (630 nm)] and two light intensities (0.3 and 0.6 W m?2) over a 9-days period in the olive flounder (Paralichthys olivaceus). We analysed clock genes like period 2 (Per 2) and cryptochrome 1 (Cry 1), and serotonin and arylalkylamine-N-acetyltransferase 2 (AANAT 2), which control circadian rhythms. Per 2, Cry 1, serotonin and AANAT 2 were significantly decreased during the starvation period compared to the normal feeding group. Nevertheless, their levels increased in the groups exposed to green- and blue LED light during the experimental period. These results confirmed that green and blue wavelengths are effective in maintaining the circadian rhythm in olive flounder.  相似文献   
979.
Diabetic cognitive impairment (DCI) is a common diabetic complication with hallmarks of loss of learning ability and disorders of memory and behavior. Glucocorticoid receptor (GR) dysfunction is a main reason for neuronal impairment in brain of diabetic patients. Here, we determined that ipriflavone (IP) a clinical anti‐osteoporosis drug functioned as a non‐steroidal GR antagonist and efficiently ameliorated learning and memory dysfunction in both type 1 and 2 diabetic mice. The underlying mechanism has been intensively investigated by assay against the diabetic mice with GR‐specific knockdown in the brain by injection of adeno‐associated virus (AAV)‐ePHP‐siGR. IP suppressed tau hyperphosphorylation through GR/PI3K/AKT/GSK3β pathway, alleviated neuronal inflammation through GR/NF‐κB/NLRP3/ASC/Caspase‐1 pathway, and protected against synaptic impairment through GR/CREB/BDNF pathway. To our knowledge, our work might be the first to expound the detailed mechanism underlying the amelioration of non‐steroidal GR antagonist on DCI‐like pathology in mice and report the potential of IP in treatment of DCI.  相似文献   
980.
The present study was performed to explore whether and how impaired autophagy could modulate calcium/calmodulin-dependent protein kinase II (CAMKII)-regulated necrosis in the pathogenesis of acute pancreatitis (AP). Wistar rats and AR42J cells were used for AP modeling. When indicated, genetic regulation of CAMKII or ATG7 was performed prior to AP induction. AP-related necrotic injury was positively regulated by the incubation level of CAMKII. ATG7 positively modulated the level of CAMKII and necrosis following AP induction, indicating that there might be a connection between impaired autophagy and CAMKII-regulated necrosis in the pathogenesis of AP. microRNA (miR)-30b-5p was predicted and then verified as the upstream regulator of CAMKII mRNA in our setting of AP. Given that the level of miR-30b-5p was negatively correlated with the incubation levels of ATG7 after AP induction, a rescue experiment was performed and indicated that the miR-30b-5p mimic compromised ATG7 overexpression-induced upregulation of CAMKII-regulated necrosis after AP induction. In conclusion, our results indicate that ATG7-enhanced impaired autophagy exacerbates AP by promoting regulated necrosis via the miR-30b-5p/CAMKII pathway.Subject terms: Cytokines, Acute inflammation  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