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   6401篇
  免费   327篇
  国内免费   8篇
耳鼻咽喉   128篇
儿科学   374篇
妇产科学   128篇
基础医学   600篇
口腔科学   92篇
临床医学   340篇
内科学   1156篇
皮肤病学   146篇
神经病学   417篇
特种医学   227篇
外科学   969篇
综合类   546篇
预防医学   345篇
眼科学   272篇
药学   434篇
  1篇
中国医学   18篇
肿瘤学   543篇
  2022年   73篇
  2021年   141篇
  2020年   82篇
  2019年   109篇
  2018年   130篇
  2017年   92篇
  2016年   136篇
  2015年   131篇
  2014年   211篇
  2013年   268篇
  2012年   352篇
  2011年   415篇
  2010年   288篇
  2009年   255篇
  2008年   334篇
  2007年   375篇
  2006年   368篇
  2005年   279篇
  2004年   306篇
  2003年   242篇
  2002年   197篇
  2001年   160篇
  2000年   173篇
  1999年   154篇
  1998年   73篇
  1997年   74篇
  1996年   74篇
  1995年   50篇
  1994年   42篇
  1993年   36篇
  1992年   67篇
  1991年   50篇
  1990年   47篇
  1989年   58篇
  1988年   50篇
  1987年   66篇
  1986年   55篇
  1985年   61篇
  1984年   55篇
  1983年   34篇
  1979年   27篇
  1978年   34篇
  1977年   32篇
  1974年   35篇
  1973年   50篇
  1972年   43篇
  1971年   37篇
  1970年   30篇
  1969年   35篇
  1968年   36篇
排序方式: 共有6736条查询结果,搜索用时 15 毫秒
31.
32.
We have previously isolated a drug-resistant, [PC3(R)], variant of human prostate PC3 cell line, which showed significant resistance (>10-fold) to adriamycin. No known mechanisms of drug resistance were found; however, resistant cells expressed more bcl2, c-myc, and ms oncogenes compared to the sensitive cells. In this study, we found that buthionine sulfoximine (BSO), an inhibitor of gamma-glutamyl-cysteine synthetase, decreased glutathione levels by 80-90% in both cell lines. BSO treatment down-modulated Ras protein only in PC3(R) cells and caused a 4-fold sensitization of PC3(R) cells to adriamycin without affecting PC3(W) cells. Farnesol treatment also inhibited expression of Ras protein and concomitantly reversed adriamycin resistance in PC3(R) cells, indicating that altered levels of ras expression plays an important role in drug resistance in PC3(R) cells.  相似文献   
33.
The Caribbean Food and Nutrition Institute conducted a survey of anemia status of pregnant and/or lactating women in Jamaica (1982), Montserrat (1981), and St. Vincent and the Grenadines (1985). After various interventions designed to reduce the prevalence of anemia in pregnant women, follow-up surveys were conducted in the same countries five years after the initial surveys to determine whether or not the prevalence of anemia in pregnant women did indeed fall after these interventions. As of July 1984, the Jamaica Flour Mills began fortifying all baking flour and counter flour with iron (44 mg/kg) (a 70% increase in the amount of iron added), thiamine (6.3 mg/kg), riboflavin (3.9 mg/kg), and niacin (52.8 mg/kg). During the five year period following the initial survey in Montserrat, health workers had changed the type of iron administered to pregnant women, a constant supply of iron tablets was established, and the economy had improved. The changes in St. Vincent and the Grenadines were that the government provided a constant supply of iron folate (ferrous folate) tablets and there was a 1988 workshop on a manual on the control of anemia where nurses were trained in better clinic management of anemia. The prevalence of anemia (Hb 11 g/dl) in pregnant women fell from 61.6% to 53% (p 0.09) in Jamaica. It fell from 82.3% to 22.1% in Montserrat (p 0.0001). The prevalence of anemia (Hb 10 g/dl) in pregnant women fell from 25% to 14.5% (p 0.001) in St. Vincent and the Grenadines. These findings show that different interventions may have contributed to the reduction in the prevalence of anemia in pregnant women in Jamaica, Montserrat, and St. Vincent and the Grenadines.  相似文献   
34.
We report a rare case of Retroperitonial teratoma containing Axial Skeleton long bone. Jaw, pelvis & scapula in a 27 yrs old male. Aberration in monozygotic twinning may rarely present as Fetus in Fetu. Rarer is presentation in Adult.  相似文献   
35.
36.
37.
Central pathways transmit pain from peripheral regions to one of the most important area of the descending pain modulatory system, the Periaqueductal gray (PAG). Independent discoveries in the past suggest that the PAG contains afferent input, output neurons and intrinsic interneurons. An attempt was made in the present study to find out the effects of more than one kind of noxious stimulus on the PAG neuronal activity. Experiments were conducted in rhesus monkeys and the effects of noxious mechanical, thermal and tooth-pulp stimulation on the activity of 14 neurons were studied. The neurons responded to more than one kind of noxious stimuli by increasing or decreasing its firing rate. No limb specificity could be identified and homogeneous distribution of the excitatory and inhibitory neurons was found.  相似文献   
38.
39.
Two patients of traumatic rupture of main bronchus are reported here. One patient presented 2 years after blunt chest trauma while the other patient presented 9 weeks after trauma. Lesion in both patients were missed in the immediate post-trauma period. In both patients pulmonary angiogram demonstrated normal vasculature in the atelectatic lung, while intraoperatively good compliance and elasticity were found. Bronchoplasty done in both patients had good postoperative results.  相似文献   
40.
Suramin, a highly sulfonated drug, has been reported to be effective against several human malignancies in vitro and in vivo, and currently is undergoing clinical trials against prostate tumors. The biochemical and molecular mechanisms for suramin's antiproliferative activity are not clear. In order to define the biochemical basis for its antitumor activity and to enhance suramin's chemotherapeutic potential while decreasing its toxicity, we have examined interactions of suramin with topoisomerase I and 11 and several clinically active anticancer drugs against the human prostate (PC3 and LNCaP) cancer cell line. While etoposide, m-AMSA, camptothecin, and SN-38 (the active metabolite of CPT-11) were active in killing prostate cells as single agents, combinations of suramin and these agents were antagonistic against these cells. We found that suramin inhibited activities of purified topoisomerase I and II in vitro as measured by relaxation and cleavage assays. Further studies indicated that suramin also inhibited the drug-induced DNA damage in vitro and in isolated nuclei. These findings indicate that combinations of suramin with topoisomerase inhibitors, for example, VP-16, m-AMSA, or CPT, may not be beneficial to patients receiving suramin-containing chemotherapy. © 1993 Wiley-Liss, Inc.
  • 1 This article is a US Government work and, as such, is in the public domain in the United States of America
  • .  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