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   2376827篇
  免费   173330篇
  国内免费   3379篇
耳鼻咽喉   32278篇
儿科学   76889篇
妇产科学   63457篇
基础医学   351379篇
口腔科学   64228篇
临床医学   215923篇
内科学   461800篇
皮肤病学   52085篇
神经病学   187801篇
特种医学   88574篇
外国民族医学   492篇
外科学   356230篇
综合类   48004篇
现状与发展   12篇
一般理论   902篇
预防医学   186513篇
眼科学   54706篇
药学   176770篇
  11篇
中国医学   4589篇
肿瘤学   130893篇
  2021年   19440篇
  2019年   20019篇
  2018年   27575篇
  2017年   20735篇
  2016年   23158篇
  2015年   26094篇
  2014年   36753篇
  2013年   55059篇
  2012年   76204篇
  2011年   80939篇
  2010年   47917篇
  2009年   45349篇
  2008年   76161篇
  2007年   81094篇
  2006年   81829篇
  2005年   79302篇
  2004年   75889篇
  2003年   73070篇
  2002年   70694篇
  2001年   109155篇
  2000年   111839篇
  1999年   93895篇
  1998年   27388篇
  1997年   23938篇
  1996年   24331篇
  1995年   22994篇
  1994年   21141篇
  1993年   19959篇
  1992年   72323篇
  1991年   70344篇
  1990年   68709篇
  1989年   65949篇
  1988年   60597篇
  1987年   59368篇
  1986年   55459篇
  1985年   53233篇
  1984年   39521篇
  1983年   33604篇
  1982年   20079篇
  1979年   36040篇
  1978年   25812篇
  1977年   21370篇
  1976年   20504篇
  1975年   21961篇
  1974年   26313篇
  1973年   25000篇
  1972年   23338篇
  1971年   22147篇
  1970年   20367篇
  1969年   19400篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
A retrospective review was conducted of 1,230 human poison exposures in which syrup of ipecac was administered to determine the availability of this emetic. Ipecac was available in 41.1% of the homes, while 42.5% obtained it from the pharmacy. Eight and two tenths percent were referred to a health care facility, 2.9% obtained ipecac from a neighbor, 2.3% went to an emergency room prior to calling the poison center, and 3% obtained ipecac from other sources. A randomly selected sample of 150 of these 1,230 cases were contacted 6 months after their initial call to the poison center to determine any changes in the availability of syrup of ipecac in the home. Although almost 30% more homes had syrup of ipecac than previously, 22.2% of homes still did not have ipecac available, despite the previous poisoning experience. Greater effort should be made during follow-up to educate the public regarding ipecac and its use.  相似文献   
972.
973.
This study reports the purification and characterization of a high molecular weight human breast cancer-associated antigen identified by a previously described (1,2) murine monoclonal antibody, BCD-B4. Immunohistochemical analysis indicated that BCD-B4 recognizes an antigen expressed in an altered form on the human breast carcinoma cell line, BT-20, compared to the non-malignant human mammary epithelial cell line, HBL-100. Chemical treatments and enzymatic digestions suggested that the recognized moiety was a protein. The antigenic determinant was resistant to neuraminidase and periodate treatments but was sensitive to trypsin and proteinase K. The antigen was purified by affinity chromatography and its molecular weight, determined by SDS-PAGE analysis under non-reducing conditions, was proven to be 250 Kd. Under reducing conditions, the molecule dissociated into two polypeptides of 125 and 45 Kd, respectively. Both subunits could be isolated from normal HBL-100 and neoplastic BT-20 cellular protein extracts by affinity chromatography. The higher molecular weight subunit showed; however, qualitative and quantitative differences between the two cell lines: it was expressed in greater quantity on BT-20 cells and its molecular weight was 15 Kd higher. Both subunits could also be identified by immunoblots of BT-20 cells.  相似文献   
974.
975.
976.
977.
Nye  Robert A. 《JAMA》2002,288(10):1294-1295
  相似文献   
978.
Interest in inguinal hernia surgery has increased significantly with the introduction of new operating techniques during the past decade. This multicenter study compared short-term results in patients treated by the laparoscopic transabdominal preperitoneal patch technique (TAPP; n=518) and the Shouldice technique (n=524). We evaluated demographics, operative data, complications, hospital stay, postoperative pain, use of analgesics, functional status, sick leave, and complaints up to 3 months postoperatively. The median operating time was shorter in the Shouldice group (55 vs. 65 min), but there were no significant differences in complication rates, and major complications were rare. The hospital stay was 1 day or less in over 98% of cases in both groups, but more operations were performed on outpatient basis in the Shouldice group. In the TAPP group postoperative pain and analgesic consumption were less, postoperative functional status was better, and sick leave was shorter (10 vs. 14 days). These results show that the two methods are equally safe and have few major complications. The TAPP operation is associated with less postoperative pain, better postoperative functional status, and shorter sick leave, but at the price of a longer operating time. Electronic Publication  相似文献   
979.
980.
The neuroprotective effects of dizocilipine maleate (MK-801), a noncompetitive antagonist of the N-methyl-D-aspartate (NMDA) receptor/channel, were tested in the 4-vessel occlusion rat model of forebrain ischemia. Adult Wistar rats, treated intraperitoneally with MK-801 or saline using several different treatment paradigms were subjected to 5 (n = 208) or 15 (n = 62) min of severe, transient forebrain ischemia. In saline-treated animals, 15 min of ischemia (n = 13) produced extensive and consistent loss of pyramidal neurons in the CA1 zone of hippocampus. The degree and distribution of cell loss were not reduced by single dose preischemic administration of MK-801 at 1 (n = 7), 2.5 (n = 4), or 5 mg/kg (n = 8). In other animals subjected to 15 min of forebrain ischemia, multiple doses of MK-801 (5, 2.5, and 2.5 mg/kg) given immediately and at approximately 8 and 20 hr after cerebral reperfusion (n = 5) did not alter CA1 injury compared to saline-treated controls (n = 5). Five minutes of forebrain ischemia in saline-treated animals, (n = 82) resulted in significantly fewer (p less than 0.001) dead CA1 pyramidal cells and a greater variance compared to animals subjected to 15 min of ischemia. Power analysis of the preliminary saline-treated animals subjected to 5 min of ischemia (n = 22) indicated that 60 animals per group were necessary to detect a 15% difference between MK-801 and vehicle-treated groups. Multidose treatment with MK-801 (1 mg/kg) given 1 hr prior to 5 min of ischemia (n = 60) and again at approximately 8 and 16 hr after recirculation failed to attenuate hippocampal injury.(ABSTRACT TRUNCATED AT 250 WORDS)  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