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   3423877篇
  免费   244740篇
  国内免费   11243篇
耳鼻咽喉   45625篇
儿科学   112259篇
妇产科学   94493篇
基础医学   484597篇
口腔科学   94399篇
临床医学   320774篇
内科学   666072篇
皮肤病学   78122篇
神经病学   283336篇
特种医学   129221篇
外国民族医学   1051篇
外科学   500047篇
综合类   73331篇
现状与发展   9篇
一般理论   1344篇
预防医学   273209篇
眼科学   76872篇
药学   250761篇
  17篇
中国医学   7887篇
肿瘤学   186434篇
  2021年   26921篇
  2019年   27829篇
  2018年   39037篇
  2017年   29837篇
  2016年   34054篇
  2015年   38515篇
  2014年   53071篇
  2013年   80738篇
  2012年   107982篇
  2011年   114360篇
  2010年   68700篇
  2009年   65023篇
  2008年   106210篇
  2007年   112421篇
  2006年   114067篇
  2005年   109366篇
  2004年   104876篇
  2003年   101111篇
  2002年   97724篇
  2001年   159313篇
  2000年   163495篇
  1999年   138005篇
  1998年   40308篇
  1997年   35813篇
  1996年   35794篇
  1995年   34541篇
  1994年   31892篇
  1993年   29975篇
  1992年   108320篇
  1991年   104742篇
  1990年   101565篇
  1989年   97735篇
  1988年   89777篇
  1987年   88047篇
  1986年   83028篇
  1985年   79333篇
  1984年   59331篇
  1983年   50647篇
  1982年   30174篇
  1979年   52949篇
  1978年   37600篇
  1977年   31532篇
  1976年   29783篇
  1975年   31364篇
  1974年   37424篇
  1973年   35830篇
  1972年   33481篇
  1971年   31152篇
  1970年   28837篇
  1969年   27302篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
Summary Cytosine arabinsodie (ara-C) and etoposide (VP-16) display synergy in the laboratory. Twenty-six patients participated in a phase I study of high-dose ara-C in combination with VP-16. The dose of VP-16 was held constant at 50 mg/m2 as an intermittent infusion over 33 h; escalating doses of ara-C were given as infusions during hours 9–12 and 21–24. Myelosuppression was the dose-limiting toxicity and occurred with doses considerably less than those expected from studies of the two drugs as single agents. The suggested initial doses for phase II trials with this schedule are 750 mg/m2×2 doses of ara-C and 50 mg/m2 of VP-16. Nonhematologic toxicity was minimal; therefore, further dose escalation is feasible in patients in whom myelosuppression is acceptable.Supported in part by grants from the National Cancer Institute (CA-12197 and CA-09422) and the American Cancer Society CF-85-182  相似文献   
993.
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   
994.
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   
995.
996.
997.
998.
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   
999.
The use of parenteral nutrition is becoming more widespread. The need for individualized parenteral nutrition solutions in pediatric patients makes the ordering and preparation of these solutions more complex and error-prone. A computer program is described which performs comprehensive management of parenteral nutrition by assisting in accurately ordering and preparing parenteral nutrition solutions. It also performs extensive error-checking and provides additional nutritional information. Data base management is also a feature which permits future large scale analysis of parenteral nutrition data for research purposes. This program, designed to run on a personal computer, is very comprehensive, yet flexible and user-friendly.  相似文献   
1000.
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   
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