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   15742篇
  免费   1377篇
  国内免费   1595篇
  18714篇
  2024年   37篇
  2023年   221篇
  2022年   574篇
  2021年   865篇
  2020年   654篇
  2019年   744篇
  2018年   711篇
  2017年   523篇
  2016年   671篇
  2015年   994篇
  2014年   1149篇
  2013年   1276篇
  2012年   1528篇
  2011年   1284篇
  2010年   789篇
  2009年   758篇
  2008年   818篇
  2007年   690篇
  2006年   604篇
  2005年   550篇
  2004年   396篇
  2003年   397篇
  2002年   357篇
  2001年   243篇
  2000年   208篇
  1999年   238篇
  1998年   133篇
  1997年   144篇
  1996年   137篇
  1995年   120篇
  1994年   116篇
  1993年   88篇
  1992年   96篇
  1991年   74篇
  1990年   82篇
  1989年   61篇
  1988年   58篇
  1987年   43篇
  1986年   50篇
  1985年   50篇
  1984年   33篇
  1983年   21篇
  1982年   22篇
  1981年   11篇
  1980年   10篇
  1979年   16篇
  1978年   6篇
  1977年   12篇
  1976年   9篇
  1973年   9篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
111.
112.
正Glaucoma is the second leading cause of blindness after cataract worldwide. However, among irreversible blinding eye diseases, glaucoma is the primary cause (Liang et al.,2011). To date, most studies have indicated that glaucoma is not only an ocular disease, but also an optic nerve disease. In  相似文献   
113.
Gao  Dawen  Liu  Fengqin  Xie  Yue  Liang  Hong 《Applied microbiology and biotechnology》2018,102(16):7195-7205
Applied Microbiology and Biotechnology - Ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) contribute significantly to the nitrogen cycle. The community structure of AOA and AOB...  相似文献   
114.
115.
BackgroundEpidermal growth factor receptor (EGFR) is highly expressed in pancreatic ductal adenocarcinoma (PDAC) and is involved in tumorigenesis and development. However, EGFR expression alone has limited clinical and prognostic significance. Recently, the cross-talk between EGFR and G-protein-coupled chemokine receptor CXCR4 has become increasingly recognized.MethodsIn the present study, immunohistochemical staining of EGFR and CXCR4 was performed on paraffin-embedded specimens from 131 patients with surgically resected PDAC. Subsequently, the associations between EGFR expression, CXCR4 expression, EGFR/CXCR4 coexpression and clinicopathologic factors were assessed, and survival analyses were performed.ResultsIn total, 64 (48.9%) patients expressed EGFR, 68 (51.9%) expressed CXCR4, and 33 (25.2%) coexpressed EGFR and CXCR4. No significant association between EGFR and CXCR4 expression was observed (P = 0.938). EGFR expression significantly correlated with tumor differentiation (P = 0.031), whereas CXCR4 expression significantly correlated with lymph node metastasis (P = 0.001). EGFR/CXCR4 coexpression was significantly associated with lymph node metastasis (P = 0.026), TNM stage (P = 0.048), and poor tumor differentiation (P = 0.004). By univariate survival analysis, both CXCR4 expression and EGFR/CXCR4 coexpression were significant prognostic factors for poor disease-free survival (DFS) and overall survival (OS). Moreover, EGFR/CXCR4 coexpression significantly increased the hazard ratio for both recurrence and death compared with EGFR or CXCR4 protein expression alone. Multivariate survival analysis demonstrated that EGFR/CXCR4 coexpression was an independent prognostic factor for DFS (HR = 2.33, P<0.001) and OS (HR = 2.48, P = 0.001).ConclusionsIn conclusion, our data indicate that although EGFR expression alone has limited clinical and prognostic significance, EGFR/CXCR4 coexpression identified a subset of PDAC patients with more aggressive tumor characteristics and a significantly worse prognosis. Our results suggest a potentially important "cross-talk" between CXCR4 and EGFR intracellular pathways and indicate that the simultaneous inhibition of these pathways might be an attractive therapeutic strategy for PDAC.  相似文献   
116.
Adenosine triphosphate (ATP) acts on P2X receptors to initiate signal transmission. P2X7 receptors play a role in the pathophysiological process of myocardial ischemic injury. Long noncoding RNAs (lncRNAs) participate in numerous biological functions independent of protein translation. LncRNAs are implicated in nervous system diseases. This study investigated the effects of NONRATT021972 small interference RNA (siRNA) on the pathophysiologic processes mediated by P2X7 receptors in stellate ganglia (SG) after myocardial ischemic injury. Our results demonstrated that the expression of NONRATT021972 in SG was significantly higher in the myocardial ischemic (MI) group than in the control group. Treatment of MI rats with NONRATT021972 siRNA, the P2X7 antagonist brilliant blue G (BBG), or P2X7 siRNA improved the histology of injured ischemic cardiac tissues and decreased the elevated concentrations of serum myocardial enzymes, creatine kinase (CK), CK isoform MB (CK-MB), lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) compared to the MI rats. NONRATT021972 siRNA, BBG, or P2X7 siRNA treatment in MI rats decreased the expression levels of P2X7 immunoreactivity, P2X7 messenger RNA (mRNA), and P2X7 protein, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and phosphorylated p38 mitogen-activated protein kinase (p38 MAPK) in the SG compared to MI rats. NONRATT021972 siRNA treatment prevented the pathophysiologic processes mediated by P2X7 receptors in the SG after myocardial ischemic injury.  相似文献   
117.
118.
119.
120.
The epidemic of rabies has rapidly increased and expanded in Yunnan province in recent years.In order to further analyze and understand the etiological reasons for the rapid expansion of rabies in Yunn...  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