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   2437485篇
  免费   181636篇
  国内免费   3747篇
耳鼻咽喉   33977篇
儿科学   79393篇
妇产科学   68485篇
基础医学   345692篇
口腔科学   71567篇
临床医学   216045篇
内科学   468045篇
皮肤病学   53250篇
神经病学   192420篇
特种医学   97455篇
外国民族医学   665篇
外科学   370402篇
综合类   56655篇
现状与发展   4篇
一般理论   772篇
预防医学   182472篇
眼科学   56273篇
药学   188102篇
  10篇
中国医学   5175篇
肿瘤学   136009篇
  2018年   23518篇
  2016年   20781篇
  2015年   23699篇
  2014年   32592篇
  2013年   48993篇
  2012年   66506篇
  2011年   70208篇
  2010年   41518篇
  2009年   39390篇
  2008年   66676篇
  2007年   70486篇
  2006年   71818篇
  2005年   69184篇
  2004年   67622篇
  2003年   64762篇
  2002年   63140篇
  2001年   119724篇
  2000年   123515篇
  1999年   104060篇
  1998年   27602篇
  1997年   24702篇
  1996年   24592篇
  1995年   23706篇
  1994年   21993篇
  1993年   20771篇
  1992年   83168篇
  1991年   80495篇
  1990年   79042篇
  1989年   76400篇
  1988年   70395篇
  1987年   69179篇
  1986年   65637篇
  1985年   62937篇
  1984年   46479篇
  1983年   39843篇
  1982年   22868篇
  1981年   20228篇
  1980年   19054篇
  1979年   43557篇
  1978年   29935篇
  1977年   25793篇
  1976年   23630篇
  1975年   25589篇
  1974年   30783篇
  1973年   29673篇
  1972年   27694篇
  1971年   26090篇
  1970年   23936篇
  1969年   22708篇
  1968年   20607篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
A 50-year-old woman with bilateral inflammatory breast cancer (T4, N1b, M1, Stage IV) underwent right extended radical mastectomy and left modified radical mastectomy following pre-operative administration of carcinostatics (ADM, 5-FU) and irradiation. However, tumor recurrence was observed at the skin and right pleural cavity after the operation. Adriamycin-containing combination chemotherapy and radiation therapy were performed, but no significant response was obtained. CDDP was then administered intravenously at a daily dose of 62.5 mg/m2 at intervals of 60 days. The pleural effusion disappeared and the extent of skin metastasis was reduced, resulting in partial response which lasted for 90 days. The serum CEA level decreased from 13.1 ng/ml to 2.3 ng/ml. As the side effects of this therapy, slight nausea, vomiting and general fatigue were observed. This result suggested that CDDP is an effective drug for inflammatory breast cancer.  相似文献   
992.
Rat brain hippocampal slices were incubated with or without the convulsant 4-aminopyridine (4-AP). From these slices a crude mitochondrial/synaptosomal membrane fraction was prepared and analyzed for endogenous protein phosphorylation. 4-AP (10(-5) M) stimulated the phosphorylation of a 50 kDa protein by 86%. The phosphorylation of this 50 kDa protein is Ca2+/calmodulin-dependent and we suggest that this protein is the lower molecular weight subunit of Ca2+/calmodulin-dependent protein kinase II (CaMK II).  相似文献   
993.
994.
This research was designed to test the extent to which health education and health services administration students' perceptions of their roles as professionals matched the expectations of professional faculty. These perceptions were found to match in general. However, doubt was cast on the extent to which internships or practicums contributed to this result, since there was no change in student responses between the beginning of the junior year and end of the senior year, a period which includes fieldwork and most of the professional coursework presumed to influence professional development. Additional research is required to test this result with other student populations in other health professions and identify the point at which professional role and task definitions are amenable to change.  相似文献   
995.
We investigated the effects of imaging and display conditions on the detectability of low-contrast objects in digital subtraction angiographic (DSA) images. The test images were produced by superimposition of low-contrast objects on a uniform noisy background obtained with a DSA system. We employed 18-alternative forced-choice (18-AFC) experiments and predictions based on statistical decision theory to study the dependence of the threshold contrasts of the test objects on the object size, incident x-ray exposure, display window width, and display medium. The results indicated that the threshold contrast decreased with increasing object size, and that the detectability of an object of a given size increased with increasing incident x-ray exposure and decreasing width of the display window. We found that the signal-to-noise ratio (SNR) obtained from the perceived statistical decision theory model, which includes the observer's internal noise, can accurately predict the detectability of low-contrast objects in DSA images. The threshold SNR corresponding to 50% correct detection in the 18-AFC experiments had a constant value of 3.8, in agreement with results reported previously for screen-film systems. The theoretical model will be useful for prediction of the performance of a DSA system based on its physical characteristics, and for evaluation of the tradeoff between patient exposure and diagnostic accuracy for a given DSA unit.  相似文献   
996.
997.
The direct actions of phencyclidine (PCP) on mammalian sarcolemma were examined by determination of the drug's effects on the action potentials of isolated guinea-pig ventricular cells, and on the underlying ionic currents. PCP (10(-6) to 10(-4) M) did not alter the resting membrane potential but produced a dose-dependent prolongation of the duration of the action potential, and a reduction of the rate of depolarization of phase 0 (Vmax) of the action potential. Voltage clamp experiments revealed that PCP blocks both myocardial Ca++ channels and myocardial time-dependent K+ channels. The K+ channel blockade was shown to exhibit an apparent voltage-dependence. The effects of PCP on these ionic channels could explain previous reports of it prolonging myocardial action potentials and conflicting reports of positive and negative inotropism.  相似文献   
998.
999.
Principles of battlefield psychiatry   总被引:2,自引:0,他引:2  
  相似文献   
1000.
Angiotensin-converting enzyme (ACE) was studied immunohistochemically in conjunctival biopsies from 6 patients with systemic sarcoidosis, 4 patients with posterior non-sarcoid uveitis and in specimens from 4 patients with chalazion of the eyelid. Specimens with sarcoid granulomas showed intense ACE-positive immunoreactivity in epitheloid cells of the granuloma, whereas chalazion granulomas did not contain ACE-immunoreactivity. There was no difference in staining patterns between specimens without granulomas. Thus immunohistochemical staining for ACE may be of help in differentiating conjunctival granulomatous tissue of a chalazion from sarcoid granuloma.  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