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   205211篇
  免费   2766篇
  国内免费   155篇
耳鼻咽喉   1437篇
儿科学   7363篇
妇产科学   3752篇
基础医学   20944篇
口腔科学   3397篇
临床医学   14895篇
内科学   37463篇
皮肤病学   1629篇
神经病学   18994篇
特种医学   9371篇
外科学   31078篇
综合类   2428篇
一般理论   21篇
预防医学   21497篇
眼科学   3230篇
药学   11839篇
中国医学   815篇
肿瘤学   17979篇
  2024年   43篇
  2023年   384篇
  2022年   873篇
  2021年   1535篇
  2020年   870篇
  2019年   1259篇
  2018年   23233篇
  2017年   18171篇
  2016年   20304篇
  2015年   2060篇
  2014年   2319篇
  2013年   2645篇
  2012年   9774篇
  2011年   23856篇
  2010年   20192篇
  2009年   12705篇
  2008年   21449篇
  2007年   23563篇
  2006年   2247篇
  2005年   3652篇
  2004年   4653篇
  2003年   5402篇
  2002年   3402篇
  2001年   359篇
  2000年   455篇
  1999年   241篇
  1998年   324篇
  1997年   323篇
  1996年   165篇
  1995年   159篇
  1994年   158篇
  1993年   103篇
  1992年   79篇
  1991年   110篇
  1990年   143篇
  1989年   93篇
  1988年   66篇
  1987年   52篇
  1986年   34篇
  1985年   40篇
  1984年   30篇
  1983年   32篇
  1982年   39篇
  1980年   52篇
  1938年   60篇
  1937年   25篇
  1935年   22篇
  1934年   30篇
  1932年   56篇
  1930年   46篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
Conclusions  Noninvasive imaging of neurohumoral upregulation in remodeled myocardium suggests that an imaging strategy can be developed for predicting the rate of remodeling and likelihood of HF development. This should allow a more judicious use of neurohumoral antagonists especially in subjects who do not have manifest HF.74 In others specific targeted imaging may allow timely selection of individualized treatment strategies and ensure optimization of therapeutic intervention. Similar to ACE and AII receptors, multiple other targets in the hormonal cascades can identify the likelihood of adverse and favorable remodeling.74  相似文献   
63.
Two successful cases of the surgical treatment for coronary artery aneurysm (non-Kawasaki disease) were reported. The first case had a saccular aneurysm on the left circumflex coronary artery (LCx) #14. Resection of the LCx aneurysm was performed subsequent to single vessel coronary artery bypass grafting (CABG) to the distal portion of LCx#14 under the cardioplegic cardiac arrest. The second case had aneurysms on both the left anterior descending artery (LAD) #7 (fusiform) and the LCx#11 (saccular). After double vessel CABG to LAD#7 and LCx#11, ligation or resection of two aneurysms was performed successfully. Postoperative courses have been uneventful with good angiographic results achieved. Since these surgical procedures demonstrated safety, the patients are expected to achieve a good long-term prognosis.  相似文献   
64.
Late-onset chylothorax occurred 49 days after right lower lobectomy for lung cancer in a 76-year-old man. Chylothorax was successfully managed by conservative treatment with chest tube drainage and an enteral low-fat diet. Chylothorax may occur in the late period after pulmonary resection and systematic mediastinal lymph node dissection for lung cancer, for which conservative management is the treatment of choice.  相似文献   
65.

Background  

Colorectal cancer, if detected early, has greater than 90% 5-year survival. However, survival has been shown to vary across racial/ethnic groups in the United States, despite the availability of early detection methods.  相似文献   
66.
Pituitary metastases of solid tumours are infrequent, specially as a first manifestation. When they happen, they are usually due to breast or lung cancer and are asymptomatic or produce diabetes insipidus. It is very strange that they produce hormonal deficiency. We present a case report of a bronchogenic adenocarcinoma in a 65-year-old man which began with panhypopituitarism, diabetes insipidus and visual alterations. Magnetic resonance imaging revealed a large sellar mass, with clivus infiltration and invading the right cavernous sinus. The biopsy result was adenocarcinoma metastases from lung cancer.  相似文献   
67.
Background. Accepted practices of informed consent often result in suboptimal patient understanding of research studies.Methods. This pilot study aimed to assess trial-specific tailored materials, compared to a widely used generic booklet about clinical trials, randomly assigned to 118 candidates for cancer clinical trials. Study outcomes were: satisfaction with decision-making; satisfaction with materials; and subjective understanding of the clinical trial.Results. There were no major differences between groups. Participants rated tailored materials higher as a useful reference.Conclusions. Trial-specific materials hold utility for reference during clinical trials. Studies of informed consent are feasible, although important factors limit research.  相似文献   
68.
The leaf essential oil of Eugenia zuchowskiae from Monteverde, Costa Rica, has been obtained by hydrodistillation and analyzed by GC–MS. The principal constituents of E. zuchowskiae leaf oil were α-pinene (28.3%), β-caryophyllene (13.2%), α-humulene (13.1%), and α-copaene (8.1%). The leaf essential oil of E. zuchowskiae showed pronounced in-vitro cytotoxic activity against MCF-7, MDA-MB-468, and UACC-257 human tumor cell lines. The major components showed cytotoxic activities comparable to doxorubicin (LC50 14–70 μg/ml).  相似文献   
69.
3β-hydroxysteroid dehydrogenase/Δ5−Δ4isomerase (3β-HSD) activity was measured in primary dissociated cell cultures prepared from telencephalons of developing zebra finches. 3β-HSD activity was confirmed after cultures were incubated with [7-3H]pregneno- lone (Preg) or (1,2,6,7-3H-) dehydroepiandrosterone (DHEA) and3H-progesterone (Prog) and3H-androstenedione (AE) were detected in the medium. Product identity was confirmed by recrystallizations and by HPLC analysis. When DHEA was used as substrate,3H-estradiol and3H-estrone were also detected in the culture medium, presumably derived from the aromatization of3H-AE or3H-T produced from3H-DHEA. To test this idea, cultures were incubated with3H-DHEA together with radioinert AE or with fadrozole HCl, a potent and specific aromatase inhibitor. In the presence of radioinert AE,3H-AE increased but metabolites of3H-AE decreased in the media; in the presence of fadrozole,3H-estrogens decreased but3H-AE and its androgenic metabolite3H-5β-androstanedione increased. These data demonstrate 3β-HSD activity in the songbird brain. The presence of Prog and estradiol in these cultures suggest that Preg and DHEA can potentially serve as substrates for the ultimate formation of active sex steroids in the songbird telencephalon.  相似文献   
70.
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