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   5648篇
  免费   624篇
  国内免费   168篇
耳鼻咽喉   56篇
儿科学   227篇
妇产科学   164篇
基础医学   139篇
口腔科学   83篇
临床医学   1261篇
内科学   1304篇
皮肤病学   132篇
神经病学   316篇
特种医学   179篇
外科学   1596篇
综合类   11篇
一般理论   2篇
预防医学   356篇
眼科学   326篇
药学   71篇
肿瘤学   217篇
  2023年   105篇
  2021年   61篇
  2020年   95篇
  2019年   41篇
  2018年   124篇
  2017年   171篇
  2016年   181篇
  2015年   135篇
  2014年   223篇
  2013年   298篇
  2012年   87篇
  2011年   105篇
  2010年   231篇
  2009年   344篇
  2008年   113篇
  2007年   58篇
  2006年   94篇
  2005年   65篇
  2003年   40篇
  2001年   107篇
  2000年   67篇
  1999年   136篇
  1998年   185篇
  1997年   212篇
  1996年   316篇
  1995年   279篇
  1994年   211篇
  1993年   129篇
  1992年   125篇
  1991年   144篇
  1990年   73篇
  1989年   143篇
  1988年   115篇
  1987年   96篇
  1986年   110篇
  1985年   93篇
  1984年   96篇
  1983年   84篇
  1982年   71篇
  1981年   74篇
  1980年   89篇
  1979年   49篇
  1978年   72篇
  1977年   50篇
  1976年   50篇
  1975年   46篇
  1974年   36篇
  1972年   38篇
  1964年   49篇
  1963年   50篇
排序方式: 共有6440条查询结果,搜索用时 24 毫秒
1.
2.
3.
4.
BACKGROUND: Abnormalities in calcium and vitamin D metabolism have been reported after bariatric surgery. The purpose of this study was to evaluate vitamin D nutritional status among morbidly obese patients before gastric bypass surgery. METHODS: We prospectively studied 279 morbidly obese patients seeking gastric bypass surgery for vitamin D nutritional status as assessed by serum 25-hydroxyvitamin D level. In addition, serum samples were analyzed for calcium, alkaline phosphatase (AP), intact parathyroid hormone (PTH), and 1,25-dihydroxyvitamin D. RESULTS: Mean patient age was 43 +/- 9 years; 87% of the study patients were women, and 72% were white. Serum calcium and AP levels were normal in 88% and 89% of the patients, respectively. Vitamin D depletion, defined as serum 25-hydroxyvitamin D level 相似文献   
5.
6.
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   
7.
8.
The Low Vision Clinic at the Palmerston North Hospital has now been oerating for 70 years. Over the course of these ten years a number of factors have emerged which can be as readily applied to general ophthalmological practice as to low vision practice. The philosophy of low vision care is one of which all ophthalmologists should be aware and includes factors to be taken into account when dealing with children, people in the workplace, and everyday factors involved in daily living activities, all of which are equally relevant in routine ophthalmological practice. This paper endeavours to share some thoughts on these factors and also discusses means by which the visually handicapped can be helped in areas where specialist low vision services are not readily available.  相似文献   
9.
A. S. C. Rice  MB  BS  Registrar  F. Reynolds  MD  FFARCS 《Anaesthesia》1987,42(12):1320-1323
Forty women who underwent gynaecological surgery were randomly allocated to receive trichloroethylene, enflurane, or enflurane plus fentanyl as adjuncts to nitrous oxide/relaxant anaesthesia with controlled ventilation. No serious cardiac dysrhythmias were seen in any group. Each patient was observed postoperatively for 4 hours by a nurse blind to the technique used, and questioned at 24 hours by a similarly blinded anaesthetist. Recovery after trichloroethylene was not significantly prolonged although postoperative analgesia by visual analogue was better, opiate analgesia was required less frequently and there was less nausea and vomiting than in either of the enflurane groups. We argue for the continued use of trichloroethylene by this technique, because it costs one hundred times less than enflurane and because of the potential morbidity of the postoperative opiate dosage required after enflurane.  相似文献   
10.
Twenty-seven women requesting postcoital contraception were randomly allocated to take an ethinylestradiol/dl-norgestrel combination or danazol. Urine specimens were assayed for luteinising hormone (LH) and pregnanediol-3-glucuronide (P3G) levels from the day of the postcoital treatment to the next period. In addition, the urine samples of these recruits and 12 additional women were assayed for the Beta-subunit of human chorionic gonadotropin (B-hCG). A consistent pattern of alteration in urinary steroids was lacking, indicating a heterogenous effect on ovarian function. There was no evidence of early pregnancy in successfully treated cases. We suggest that the main mechanism of action of these drugs is at the endometrial level.  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