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   1658745篇
  免费   137728篇
  国内免费   2741篇
耳鼻咽喉   22116篇
儿科学   54525篇
妇产科学   47299篇
基础医学   235790篇
口腔科学   48494篇
临床医学   147307篇
内科学   327110篇
皮肤病学   35013篇
神经病学   135583篇
特种医学   66471篇
外国民族医学   475篇
外科学   251992篇
综合类   40454篇
现状与发展   3篇
一般理论   602篇
预防医学   128453篇
眼科学   37909篇
药学   125414篇
  4篇
中国医学   3044篇
肿瘤学   91156篇
  2018年   16126篇
  2016年   13990篇
  2015年   16332篇
  2014年   22558篇
  2013年   34016篇
  2012年   46821篇
  2011年   49079篇
  2010年   28773篇
  2009年   27512篇
  2008年   46994篇
  2007年   49615篇
  2006年   50407篇
  2005年   48783篇
  2004年   48000篇
  2003年   45802篇
  2002年   44814篇
  2001年   76222篇
  2000年   78718篇
  1999年   66970篇
  1998年   18477篇
  1997年   16957篇
  1996年   16844篇
  1995年   16535篇
  1994年   15481篇
  1993年   14601篇
  1992年   55731篇
  1991年   54058篇
  1990年   52820篇
  1989年   51071篇
  1988年   47462篇
  1987年   46759篇
  1986年   44514篇
  1985年   43059篇
  1984年   32310篇
  1983年   27871篇
  1982年   16490篇
  1981年   14759篇
  1980年   13870篇
  1979年   30634篇
  1978年   21281篇
  1977年   17940篇
  1976年   16824篇
  1975年   17659篇
  1974年   21584篇
  1973年   20751篇
  1972年   18933篇
  1971年   17838篇
  1970年   16350篇
  1969年   15314篇
  1968年   13978篇
排序方式: 共有10000条查询结果,搜索用时 203 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.
17.
Journal of Neuro-Oncology - Adjuvant radiation is often used in patients with low grade gliomas with high-risk characteristics with a recommended dose of 45–54&nbsp;Gy. We used the...  相似文献   
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