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   3672025篇
  免费   302890篇
  国内免费   14450篇
耳鼻咽喉   49398篇
儿科学   116454篇
妇产科学   95122篇
基础医学   578907篇
口腔科学   96476篇
临床医学   331868篇
内科学   657541篇
皮肤病学   95248篇
神经病学   316920篇
特种医学   142211篇
外国民族医学   498篇
外科学   560565篇
综合类   109995篇
现状与发展   24篇
一般理论   2582篇
预防医学   309933篇
眼科学   84675篇
药学   251830篇
  25篇
中国医学   10724篇
肿瘤学   178369篇
  2021年   56667篇
  2020年   36037篇
  2019年   59494篇
  2018年   73621篇
  2017年   56226篇
  2016年   62189篇
  2015年   75884篇
  2014年   110781篇
  2013年   176556篇
  2012年   111373篇
  2011年   113344篇
  2010年   122264篇
  2009年   125356篇
  2008年   98861篇
  2007年   103747篇
  2006年   113697篇
  2005年   108775篇
  2004年   109555篇
  2003年   99303篇
  2002年   88009篇
  2001年   118793篇
  2000年   112143篇
  1999年   108145篇
  1998年   67343篇
  1997年   64763篇
  1996年   62499篇
  1995年   57877篇
  1994年   51821篇
  1993年   48331篇
  1992年   74525篇
  1991年   70126篇
  1990年   65853篇
  1989年   64657篇
  1988年   59627篇
  1987年   58361篇
  1986年   54868篇
  1985年   54675篇
  1984年   49768篇
  1983年   45300篇
  1982年   42421篇
  1981年   39783篇
  1980年   37447篇
  1979年   40383篇
  1978年   35733篇
  1977年   32399篇
  1976年   29735篇
  1975年   28040篇
  1974年   29126篇
  1973年   28145篇
  1972年   26346篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
951.
952.
953.
954.
Image-directed color Doppler ultrasonography (ICDUS) studies of 86 patients with superficial solid masses yielded significantly lower resistive index (RI) values in acute inflammatory lesions, but no significant difference between the maximum systolic flow velocities (S) of the patient groups with malignant, benign, and acute inflammatory lesions. When analyzed separately, the malignant soft-tissue tumor subgroup was shown to have significantly higher mean RI compared to that of the malignant node subgroup. We conclude that RI may be useful in the differentiation of acute inflammatory masses from other pathological entities. Malignant soft-tissue tumors, especially sarcomas, may have different Doppler features from those of carcinomatous tumors. © 1995 John Wiley & Sons, Inc.  相似文献   
955.
956.
Dantrolene seems to be the causal therapy in malignant hyperthermia (MH) crisis but the complex mechanisms of MH and dantrolene therapy are still not fully understood. The influence of dantrolene on ryanodine-induced contractures has been reported in animal studies only. In the present study 20 patients from] 7 families were tested for MH using the protocol of the European Malignant Hyperthermia Group. In addition ryanodine-induced contractures were evaluated following bolus application of 10.0 μmol · 1-1 ryanodine. After pretreatment with 1 μimol · 1-1 dantrolene ryanodine-provoked contractures developed significantly later in MHS (15.8±1.8 min) and MHN (46.0±4.2 min) muscle specimens than after ryanodine alone (MHS 4.8±0.7 min), (MHN 13.7±0.9 min). They were no longer observed in either group after pretreatment with 5 μimol · 1-1 dantrolene. We conclude that dantrolene is able to attenuate ryanodine-induced contractures dose-dependendy, and therefore it is speculated that dantrolene could specifically act at the ryanodine receptor binding site.  相似文献   
957.
PURPOSE: This study was undertaken to clarify the importance of bleeding vascular ectasia of the colon as the etiology of massive lower gastrointestinal hemorrhage in patients 40 years of age or younger. METHODS: An otherwise healthy 21-year-old male was admitted to a tertiary medical center with massive lower gastrointestinal hemorrhage. Technetium-labeled red blood cell scan, selective visceral angiography, and colonoscopy identified the source of bleeding as vascular abnormality of the descending colon. Segmental colonic resection was performed. RESULTS: Histologic review of the specimen demonstrated a vascular ectasia. The patient recovered uneventfully and has had no further stigmata of hemorrhage. A review of the literature was undertaken to make clear the significance of vascular ectasia as the source for massive colonic hemorrhage in the young adult. CONCLUSION: This is the first report that documents histologically a vascular ectasia as the source of massive lower gastrointestinal hemorrhage in an otherwise healthy patient less than 40 years of age. Vascular ectasia is an uncommon cause of lower gastrointestinal hemorrhage in the young adult.The Chief, Bureau of Medicine and Surgery, Navy Department, Washington, DC, Clinical Investigation Program sponsored this report #84-16-1968-532, as required by HSETCINST 6000.41A. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Navy, Department of Defense, or the United States Government.  相似文献   
958.
959.
960.
The aim of this research is to characterize the presence of insulin-degrading enzyme in human colon and ileal mucosal cells. Biochemical studies, including the activity-pH profiles, the effects of enzyme inhibitors, immunoprecipitation and western blots, were conducted. The majority of insulin-degrading activity in colon mucosal cells was localized in the cytosol. In both colon and ileum, cytosolic insulin-degrading activities had a pH optimum at pH 7.5, and were extensively inhibited by each of N-ethylmaleimide, p-chloromercuribenzoate, and 1,10-phenanthroline, but were very weakly affected by each of leupeptin, chymostatin, diisopropyl phosphofluoridate and soybean trypsin inhibitor. In the colon and ileum, more than 93% and 96%, respectively, of cytosolic insulin-degrading activities were removed by the mouse monoclonal antibody to human RBC insulin-degrading enzyme, as compared with less than 20% by the normal mouse IgG for both tissues. Further, a western blot analysis revealed that a cytosolic protein of 110 kD, in both human colon and ileum, reacted with the monoclonal antibody to insulin-degrading enzyme. It is concluded that insulin-degrading enzyme is present in the cytosol of human colon and ileal mucosal cells.  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