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   143065篇
  免费   8945篇
  国内免费   1614篇
耳鼻咽喉   1976篇
儿科学   3678篇
妇产科学   4826篇
基础医学   21456篇
口腔科学   4224篇
临床医学   12226篇
内科学   25703篇
皮肤病学   2626篇
神经病学   9787篇
特种医学   4835篇
外国民族医学   3篇
外科学   20391篇
综合类   5737篇
一般理论   47篇
预防医学   11575篇
眼科学   3250篇
药学   11896篇
中国医学   863篇
肿瘤学   8525篇
  2021年   1319篇
  2019年   1398篇
  2018年   2007篇
  2017年   1462篇
  2016年   1485篇
  2015年   1791篇
  2014年   2360篇
  2013年   3172篇
  2012年   4628篇
  2011年   4877篇
  2010年   2882篇
  2009年   2573篇
  2008年   4378篇
  2007年   4698篇
  2006年   4554篇
  2005年   4109篇
  2004年   3955篇
  2003年   3667篇
  2002年   3479篇
  2001年   7575篇
  2000年   7767篇
  1999年   6402篇
  1998年   2181篇
  1997年   1708篇
  1996年   1245篇
  1995年   1164篇
  1992年   4322篇
  1991年   4319篇
  1990年   4049篇
  1989年   4035篇
  1988年   3902篇
  1987年   3697篇
  1986年   3551篇
  1985年   3416篇
  1984年   2405篇
  1983年   2089篇
  1982年   1190篇
  1979年   2253篇
  1978年   1417篇
  1977年   1205篇
  1976年   1076篇
  1975年   1371篇
  1974年   1583篇
  1973年   1616篇
  1972年   1553篇
  1971年   1407篇
  1970年   1307篇
  1969年   1317篇
  1968年   1199篇
  1967年   1035篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
62.
63.
OBJECTIVE: To compare mid-gestation sonographic measurements of all five digits of the hands of fetuses with Down syndrome with those of normal controls. METHODS: Twenty-nine fetuses between 17 and 26 weeks' gestation which had been confirmed by karyotyping to have Down syndrome were included in this prospective study. Each fetus was scanned once and the digits of only one hand were measured. Measurements were compared with those of 302 previously reported normal controls matched for gestational age. All measurements were expressed in multiples of the gestation-specific normal median (MoM) for each digit. RESULTS: Compared to 1 MoM for the length of Digits 1 to 5 from the normal population, the respective values in the Down syndrome digits were: 0.94, 0.85, 0.92, 0.88 and 0.85 MoM, representing values significantly lower than normal (P < 0.05; t-test). CONCLUSIONS: All five digits of the hands of fetuses with Down syndrome are shorter than are those of euploid fetuses. Integration of fetal digit measurement into the antenatal assessment of selected high-risk cases may be of value although confirmation of our findings should be obtained before this measurement is incorporated into Down syndrome screening in the general population.  相似文献   
64.
65.
66.
67.
68.
Background: Dreaming reported after anesthesia remains a poorly understood phenomenon. Dreaming may be related to light anesthesia and represent near-miss awareness. However, few studies have assessed the relation between dreaming and depth of anesthesia, and their results were inconclusive. Therefore, the authors tested the hypothesis that dreaming during anesthesia is associated with light anesthesia, as evidenced by higher Bispectral Index values during maintenance of anesthesia.

Methods: With approval, 300 consenting healthy patients, aged 18-50 yr, presenting for elective surgery requiring relaxant general anesthesia with a broad range of agents were studied. Patients were interviewed on emergence and 2-4 h postoperatively. The Bispectral Index was recorded from induction until the first interview. Dream content and form were also assessed.

Results: Dreaming was reported by 22% of patients on emergence. There was no difference between dreamers and nondreamers in median Bispectral Index values during maintenance (37 [23-55] vs. 38 [20-59]; P = 0.68) or the time at Bispectral Index values greater than 60 (0 [0-7] vs. 0 [0-31] min; P = 0.38). Dreamers tended to be younger and male, to have high home dream recall, to receive propofol maintenance or regional anesthesia, and to open their eyes sooner after surgery. Most dreams were similar to dreams of sleep and were pleasant, and the content was unrelated to surgery.  相似文献   

69.
70.
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