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   2015553篇
  免费   153105篇
  国内免费   2986篇
耳鼻咽喉   27179篇
儿科学   66122篇
妇产科学   55761篇
基础医学   302254篇
口腔科学   57133篇
临床医学   180510篇
内科学   385629篇
皮肤病学   43440篇
神经病学   156001篇
特种医学   80022篇
外国民族医学   523篇
外科学   305025篇
综合类   45495篇
现状与发展   4篇
一般理论   631篇
预防医学   154183篇
眼科学   46170篇
药学   153692篇
  4篇
中国医学   3753篇
肿瘤学   108113篇
  2018年   19163篇
  2016年   16694篇
  2015年   19077篇
  2014年   26151篇
  2013年   39506篇
  2012年   54541篇
  2011年   58438篇
  2010年   34246篇
  2009年   32139篇
  2008年   55228篇
  2007年   58996篇
  2006年   59395篇
  2005年   57474篇
  2004年   56598篇
  2003年   54345篇
  2002年   53056篇
  2001年   91576篇
  2000年   94431篇
  1999年   79806篇
  1998年   21765篇
  1997年   19608篇
  1996年   19566篇
  1995年   19026篇
  1994年   17822篇
  1993年   16918篇
  1992年   65904篇
  1991年   65744篇
  1990年   64733篇
  1989年   62828篇
  1988年   58362篇
  1987年   57636篇
  1986年   54485篇
  1985年   52702篇
  1984年   39341篇
  1983年   33868篇
  1982年   19424篇
  1981年   17466篇
  1979年   37563篇
  1978年   26218篇
  1977年   21894篇
  1976年   21222篇
  1975年   23061篇
  1974年   27682篇
  1973年   26601篇
  1972年   24461篇
  1971年   23106篇
  1970年   21317篇
  1969年   19918篇
  1968年   18396篇
  1967年   16601篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
13.
14.
15.
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   
16.
Journal of Immigrant and Minority Health - COVID-19 has disproportionally affected underrepresented minorities (URM) and low-income immigrants in the United States. The aim of the study is to...  相似文献   
17.
18.
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   
19.
20.
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   
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