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   205377篇
  免费   2869篇
  国内免费   158篇
耳鼻咽喉   1438篇
儿科学   7381篇
妇产科学   3695篇
基础医学   20350篇
口腔科学   2270篇
临床医学   14675篇
内科学   38633篇
皮肤病学   1361篇
神经病学   19179篇
特种医学   9539篇
外国民族医学   1篇
外科学   33416篇
综合类   2481篇
一般理论   11篇
预防医学   20340篇
眼科学   3500篇
药学   11202篇
  1篇
中国医学   707篇
肿瘤学   18224篇
  2023年   198篇
  2022年   515篇
  2021年   1081篇
  2020年   525篇
  2019年   961篇
  2018年   22908篇
  2017年   17906篇
  2016年   20118篇
  2015年   1780篇
  2014年   1953篇
  2013年   2240篇
  2012年   9231篇
  2011年   23359篇
  2010年   20049篇
  2009年   12701篇
  2008年   21309篇
  2007年   23567篇
  2006年   2394篇
  2005年   3902篇
  2004年   4914篇
  2003年   5705篇
  2002年   3682篇
  2001年   715篇
  2000年   845篇
  1999年   586篇
  1998年   472篇
  1997年   444篇
  1996年   283篇
  1995年   261篇
  1994年   251篇
  1993年   167篇
  1992年   278篇
  1991年   311篇
  1990年   320篇
  1989年   236篇
  1988年   222篇
  1987年   175篇
  1986年   167篇
  1985年   145篇
  1984年   123篇
  1983年   108篇
  1982年   100篇
  1981年   69篇
  1980年   100篇
  1979年   58篇
  1978年   56篇
  1976年   54篇
  1974年   92篇
  1938年   63篇
  1932年   56篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
International Journal of Clinical Oncology - Immune-checkpoint inhibitors (ICIs) are standard treatments for metastatic non-small cell lung cancer (NSCLC). Patients with poor performance status...  相似文献   
3.
4.
5.
Magnetic field generated by neuronal activity could alter magnetic resonance imaging (MRI) signals but detection of such signal is under debate. Previous researches proposed that magnitude signal change is below current detectable level, but phase signal change (PSC) may be measurable with current MRI systems. Optimal imaging parameters like echo time, voxel size and external field direction, could increase the probability of detection of this small signal change. We simulate a voxel of cortical column to determine effect of such parameters on PSC signal. We extended a laminar network model for somatosensory cortex to find neuronal current in each segment of pyramidal neurons (PN). 60,000 PNs of simulated network were positioned randomly in a voxel. Biot–savart law applied to calculate neuronal magnetic field and additional phase. The procedure repeated for eleven neuronal arrangements in the voxel. PSC signal variation with the echo time and voxel size was assessed. The simulated results show that PSC signal increases with echo time, especially 100/80 ms after stimulus for gradient echo/spin echo sequence. It can be up to 0.1 mrad for echo time = 175 ms and voxel size = 1.48 × 1.48 × 2.18 mm3. With echo time less than 25 ms after stimulus, it was just acquired effects of physiological noise on PSC signal. The absolute value of the signal increased with decrease of voxel size, but its components had complex variation. External field orthogonal to local surface of cortex maximizes the signal. Expected PSC signal for tactile detection in the somatosensory cortex increase with echo time and have no oscillation.  相似文献   
6.
7.
In the current immunosuppressive therapy era, vessel thrombosis is the most common cause of early graft loss after renal transplantation. The prevalence of IgA anti–β2-glycoprotein I antibodies (IgA-aB2GPI-ab) in patients on dialysis is elevated (>30%), and these antibodies correlate with mortality and cardiovascular morbidity. To evaluate the effect of IgA-aB2GPI-ab in patients with transplants, we followed all patients transplanted from 2000 to 2002 in the Hospital 12 de Octubre prospectively for 10 years. Presence of IgA-aB2GPI-ab in pretransplant serum was examined retrospectively. Of 269 patients, 89 patients were positive for IgA-aB2GPI-ab (33%; group 1), and the remaining patients were negative (67%; group 2). Graft loss at 6 months post-transplant was significantly higher in group 1 (10 of 89 versus 3 of 180 patients in group 2; P=0.002). The most frequent cause of graft loss was thrombosis of the vessels, which was observed only in group 1 (8 of 10 versus 0 of 3 patients in group 2; P=0.04). Multivariate analysis showed that the presence of IgA-aB2GPI-ab was an independent risk factor for early graft loss (P=0.04) and delayed graft function (P=0.04). There were no significant differences regarding patient survival between the two groups. Graft survival was similar in both groups after 6 months. In conclusion, patients with pretransplant IgA-aB2GPI-ab have a high risk of early graft loss caused by thrombosis and a high risk of delayed graft function. Therefore, pretransplant IgA-aB2GPI-ab may have a detrimental effect on early clinical outcomes after renal transplantation.  相似文献   
8.
9.
10.
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