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   20367篇
  免费   2209篇
  国内免费   1201篇
耳鼻咽喉   158篇
儿科学   392篇
妇产科学   192篇
基础医学   2145篇
口腔科学   389篇
临床医学   2242篇
内科学   3262篇
皮肤病学   338篇
神经病学   1102篇
特种医学   888篇
外国民族医学   5篇
外科学   2470篇
综合类   3455篇
现状与发展   5篇
一般理论   4篇
预防医学   1594篇
眼科学   347篇
药学   2236篇
  10篇
中国医学   1066篇
肿瘤学   1477篇
  2024年   16篇
  2023年   186篇
  2022年   277篇
  2021年   637篇
  2020年   567篇
  2019年   625篇
  2018年   695篇
  2017年   614篇
  2016年   744篇
  2015年   936篇
  2014年   1109篇
  2013年   1272篇
  2012年   1579篇
  2011年   1691篇
  2010年   1321篇
  2009年   1191篇
  2008年   1209篇
  2007年   1254篇
  2006年   1126篇
  2005年   974篇
  2004年   1021篇
  2003年   1103篇
  2002年   984篇
  2001年   726篇
  2000年   465篇
  1999年   313篇
  1998年   163篇
  1997年   182篇
  1996年   112篇
  1995年   72篇
  1994年   84篇
  1993年   47篇
  1992年   52篇
  1991年   61篇
  1990年   45篇
  1989年   45篇
  1988年   29篇
  1987年   37篇
  1986年   23篇
  1985年   15篇
  1984年   18篇
  1983年   14篇
  1982年   14篇
  1980年   8篇
  1979年   14篇
  1977年   11篇
  1975年   8篇
  1974年   8篇
  1971年   8篇
  1969年   8篇
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
1.
2.
3.
目的采用Meta分析方法评价18F-脱氧葡萄糖正电子发射计算机体层摄影(18F-FDG PET/CT)和增强CT(CECT)诊断经导管肝动脉化疗栓塞术(TACE)术后存活或复发病灶的临床价值。方法根据PRISMA报告规范开展Meta分析。检索PubMed、Embase、Cochrane Library、Web of Science、中国知网、万方和维普数据库中18F-FDG PET/CT和CECT诊断TACE术后存活或复发病灶的临床研究,时间至2019-04。由2位研究人员独立筛选文献、提取资料,根据诊断准确性研究质量评价工具-2(QUADAS-2)评价纳入研究的偏倚风险后,采用Stata 12.0软件进行Meta分析,计算其汇总敏感度(Sen)和特异度(Spe),绘制受试者工作特征曲线(SROC)并计算曲线下面积(AUC)。结果共纳入10篇18F-FDG PET/CT及13篇CECT诊断TACE术后存活或复发病灶的原始研究,分别包括322例患者的467个病灶和748例患者的943个病灶。Meta分析显示,18F-FDG PET/CT诊断TACE术后存活或复发病灶的Sen=0.92(95%CI为0.87~0.94)、Spe=0.95(95%CI为0.82~0.99)、AUC=0.97(95%CI为0.93~0.99);CECT诊断TACE术后存活或复发病灶的Sen=0.72(95%CI为0.66~0.78)、Spe=0.99(95%CI为0.93~1.00)、AUC=0.87(95%CI为0.83~0.89)。此外,CECT诊断TACE术后存活或复发Sen(Z=2.34,P=0.02)和AUC(Z=2.21,P=0.03)值低于18F-FDG PET/CT,差异有统计学意义。结论相比于CECT,18F-FDG PET/CT对TACE术后存活或复发病灶具有较高诊断效能,可视为TACE术后存活或复发病灶有效的影像学诊断方法。  相似文献   
4.
5.
6.
Helicobacter pylori (H. pylori) is a main risk factor for gastric cancer (GC). Epithelial-mesenchymal transition (EMT) is involved in the development and progression of H. pylori-associated GC. However, the exact molecular mechanism of this process remains unclear. The AKT/GSK3β signaling pathway has been demonstrated to promote EMT in several types of cancer. The present study investigated whether H. pylori infection induced EMT, and promoted the development and metastasis of cancer in the normal gastric mucosa, and whether this process was dependent on AKT activation. The expression levels of the EMT-associated proteins, including E-cadherin and N-cadherin, were determined in 165 gastric mucosal samples of different disease stages by immunohistochemical analysis. The expression levels of E-cadherin, N-cadherin, AKT, phosphorylated (p-)AKT (Ser473), GSK3β and p-GSK3β (Ser9) were further determined in H. pylori-infected Mongolian gerbil gastric tissues and cells co-cultured with H. pylori by immunohistochemical analysis and western blotting. The results indicated that the expression levels of the epithelial marker E-cadherin were decreased, whereas the expression levels of the mesenchymal marker N-cadherin were increased during gastric carcinogenesis. Their expression levels were associated with H. pylori infection. Furthermore, H. pylori infection resulted in downregulation of E-cadherin expression and upregulation of N-cadherin expression in Mongolian gerbils and GES-1 cells. In addition, an investigation of the associated mechanism of action revealed that p-AKT (Ser473) and p-GSK3β (Ser9) were activated in GES-1 cells following co-culture with H. pylori. Furthermore, following pretreatment of the cells with the AKT inhibitor VIII, the expression levels of E-cadherin, N-cadherin, p-AKT and p-GSK3β did not show significant differences between GES-1 cells that were co-cultured with or without H. pylori. The levels of p-AKT and p-GSK3β were increased in H. pylori-infected Mongolian gerbils. In conclusion, the present study demonstrated that H. pylori infection activated AKT and resulted in the phosphorylation and inactivation of GSK3β, which in turn promoted early stage EMT. These effects were AKT-dependent. This mechanism may serve as a prerequisite for GC development.  相似文献   
7.
8.
9.
10.
For advanced and metastatic urothelial carcinomas (UCs), platinum (preferably cisplatin)‐based chemotherapy has been the standard treatment for many years. However, many patients are ineligible for cisplatin‐based chemotherapy because of poor performance status and/or other age‐related conditions. At the other end of the spectrum, patients with localized non‐muscle–invasive bladder cancer who are unresponsive to intravesical Bacillus Calmette‐Guérin (BCG) treatment often face radical cystectomy as the only option. In recent years, the application of immunotherapy in the form of immune‐checkpoint inhibitors has provided viable alternatives in the second‐line postplatinum and first‐line cisplatin‐ineligible settings. Recent and ongoing clinical trials are also assessing the safety and efficacy of immunotherapy for neoadjuvant and adjuvant uses before/after cystectomy, for BCG‐unresponsive cases, and for combination treatments that include the newer indoleamine 2,3‐dioxygenase‐1 inhibitors and/or BCG. This review summarizes recent developments in immunotherapy for UCs.  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