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   1603133篇
  免费   133821篇
  国内免费   2584篇
耳鼻咽喉   21716篇
儿科学   53388篇
妇产科学   46304篇
基础医学   228244篇
口腔科学   47285篇
临床医学   141084篇
内科学   315317篇
皮肤病学   34330篇
神经病学   130263篇
特种医学   64847篇
外国民族医学   474篇
外科学   244171篇
综合类   39826篇
现状与发展   3篇
一般理论   547篇
预防医学   122938篇
眼科学   36597篇
药学   121611篇
  2篇
中国医学   2987篇
肿瘤学   87604篇
  2018年   14928篇
  2016年   13014篇
  2015年   15149篇
  2014年   20857篇
  2013年   31592篇
  2012年   42854篇
  2011年   45045篇
  2010年   26513篇
  2009年   25451篇
  2008年   43199篇
  2007年   45440篇
  2006年   46240篇
  2005年   44858篇
  2004年   44245篇
  2003年   42311篇
  2002年   41402篇
  2001年   75761篇
  2000年   78395篇
  1999年   66452篇
  1998年   17767篇
  1997年   16356篇
  1996年   16345篇
  1995年   16038篇
  1994年   15104篇
  1993年   14244篇
  1992年   55474篇
  1991年   53819篇
  1990年   52615篇
  1989年   50881篇
  1988年   47268篇
  1987年   46610篇
  1986年   44323篇
  1985年   42878篇
  1984年   32066篇
  1983年   27586篇
  1982年   16188篇
  1981年   14488篇
  1980年   13605篇
  1979年   30480篇
  1978年   21078篇
  1977年   17782篇
  1976年   16718篇
  1975年   17587篇
  1974年   21508篇
  1973年   20696篇
  1972年   18860篇
  1971年   17780篇
  1970年   16311篇
  1969年   15283篇
  1968年   13963篇
排序方式: 共有10000条查询结果,搜索用时 699 毫秒
11.
12.
Comprehensive evidence regarding the treatment of non-anaemic iron deficiency in patients undergoing valvular heart surgery is lacking. This study aimed to investigate the association between non-anaemic iron deficiency and postoperative outcomes in these patients. We retrospectively analysed 321 patients of which 180 (56%) had iron deficiency (defined as serum ferritin < 100 ng.ml-1 or < 300 ng.ml-1 with transferrin saturation < 20%). While the iron-deficient group had lower pre-operative haemoglobin levels than the non-iron deficient group (median (IQR [range]) 134 (127–141 [120–172]) g.l-1, 143 (133–150 [120–179]) g.l-1, p = 0.001), there was no between-group difference in allogeneic red blood cell transfusion. Median (IQR [range]) days alive and out of hospital at postoperative day 90 was 1 day shorter in the iron-deficient group (80 (77–82 [9–85]) days vs. 81 (79–83 [0–85]) days, p = 0.026). In multivariable analysis, only cardiopulmonary bypass duration (p = 0.032) and intra-operative allogeneic red blood cell transfusion (p = 0.011) were significantly associated with reduced days alive and out of hospital at postoperative day 90. Iron deficiency did not exert any adverse influence on secondary outcomes except length of hospital stay. Our findings indicate that non-anaemic iron deficiency alone is not associated with adverse effects in patients undergoing valvular heart surgery when it does not translate into an increased risk of allogeneic transfusion.  相似文献   
13.
14.
Cyclotron-produced copper-64 radioisotope tracers offer the possibility to perform both diagnostic investigation by positron emission tomography (PET) and radiotherapy by a theranostic approach with bifunctional chelators. The versatile chemical properties of copper add to the importance of this isotope in medicinal investigation. [64Cu][Cu (ATSM)] has shown to be a viable candidate for imaging of tumor hypoxia; a critical tumor microenvironment characteristic that typically signifies tumor progression and resistance to chemo-radiotherapy. Various production and radiosynthesis methods of [64Cu][Cu (ATSM)] exist in labs, but usually involved non-standardized equipment with varying production qualities and may not be easily implemented in wider hospital settings. [64Cu][Cu (ATSM)] was synthesized on a modified GE TRACERlab FXN automated synthesis module. End-of-synthesis (EOS) molar activity of [64Cu][Cu (ATSM)] was 2.2–5.5 Ci/μmol (HPLC), 2.2–2.6 Ci/μmol (ATSM-titration), and 3.0–4.4 Ci/μmol (ICP-MS). Radiochemical purity was determined to be >99% based on radio-HPLC. The final product maintained radiochemical purity after 20 h. We demonstrated a simple and feasible process development and quality control protocols for automated cyclotron production and synthesis of [64Cu][Cu (ATSM)] based on commercially distributed standardized synthesis modules suitable for PET imaging and theranostic studies.  相似文献   
15.
16.
Gold nanoparticles (Au NPs) hold great promise in food, industrial and biomedical applications due to their unique physicochemical properties. However, influences of the gastrointestinal tract (GIT), a likely route for Au NPs administration, on the physicochemical properties of Au NPs has been rarely evaluated. Here, we investigated the influence of GIT fluids on the physicochemical properties of Au NPs (5, 50, and 100?nm) and their implications on intestinal epithelial permeability in vitro. Au NPs aggregated in fasted gastric fluids and generated hydroxyl radicals in the presence of H2O2. Cell studies showed that GIT fluids incubation of Au NPs affected the cellular uptake of Au NPs but did not induce cytotoxicity or disturb the intestinal epithelial permeability.  相似文献   
17.
18.
19.
20.
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