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   1603569篇
  免费   133927篇
  国内免费   2583篇
耳鼻咽喉   21691篇
儿科学   53013篇
妇产科学   46337篇
基础医学   228596篇
口腔科学   47363篇
临床医学   141216篇
内科学   315437篇
皮肤病学   34237篇
神经病学   130592篇
特种医学   64890篇
外国民族医学   475篇
外科学   244233篇
综合类   39738篇
现状与发展   3篇
一般理论   549篇
预防医学   123192篇
眼科学   36462篇
药学   121512篇
  2篇
中国医学   2988篇
肿瘤学   87553篇
  2018年   14881篇
  2016年   12997篇
  2015年   15137篇
  2014年   20792篇
  2013年   31547篇
  2012年   42827篇
  2011年   45041篇
  2010年   26499篇
  2009年   25449篇
  2008年   43247篇
  2007年   45476篇
  2006年   46273篇
  2005年   44911篇
  2004年   44299篇
  2003年   42387篇
  2002年   41485篇
  2001年   75834篇
  2000年   78472篇
  1999年   66525篇
  1998年   17796篇
  1997年   16388篇
  1996年   16368篇
  1995年   16053篇
  1994年   15095篇
  1993年   14258篇
  1992年   55504篇
  1991年   53863篇
  1990年   52643篇
  1989年   50904篇
  1988年   47289篇
  1987年   46613篇
  1986年   44344篇
  1985年   42911篇
  1984年   32105篇
  1983年   27606篇
  1982年   16174篇
  1981年   14461篇
  1980年   13580篇
  1979年   30481篇
  1978年   21088篇
  1977年   17791篇
  1976年   16707篇
  1975年   17589篇
  1974年   21505篇
  1973年   20696篇
  1972年   18877篇
  1971年   17786篇
  1970年   16313篇
  1969年   15283篇
  1968年   13973篇
排序方式: 共有10000条查询结果,搜索用时 15 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