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   23234篇
  免费   1961篇
  国内免费   76篇
耳鼻咽喉   321篇
儿科学   663篇
妇产科学   565篇
基础医学   3191篇
口腔科学   495篇
临床医学   2208篇
内科学   5453篇
皮肤病学   327篇
神经病学   2118篇
特种医学   729篇
外科学   3627篇
综合类   367篇
一般理论   21篇
预防医学   1792篇
眼科学   623篇
药学   1349篇
中国医学   38篇
肿瘤学   1384篇
  2023年   159篇
  2022年   319篇
  2021年   813篇
  2020年   428篇
  2019年   639篇
  2018年   776篇
  2017年   520篇
  2016年   522篇
  2015年   638篇
  2014年   830篇
  2013年   1080篇
  2012年   1576篇
  2011年   1606篇
  2010年   873篇
  2009年   745篇
  2008年   1329篇
  2007年   1317篇
  2006年   1295篇
  2005年   1237篇
  2004年   1138篇
  2003年   994篇
  2002年   1001篇
  2001年   226篇
  2000年   202篇
  1999年   229篇
  1998年   213篇
  1997年   182篇
  1996年   167篇
  1995年   154篇
  1994年   144篇
  1993年   131篇
  1992年   162篇
  1991年   145篇
  1990年   166篇
  1989年   136篇
  1988年   145篇
  1987年   158篇
  1986年   119篇
  1985年   162篇
  1984年   141篇
  1983年   132篇
  1982年   144篇
  1981年   146篇
  1980年   182篇
  1979年   98篇
  1978年   102篇
  1977年   96篇
  1976年   104篇
  1975年   78篇
  1974年   89篇
排序方式: 共有10000条查询结果,搜索用时 109 毫秒
101.
102.
103.
104.
On-site testing of 157 poultry processors disclosed that 50% had three or more abnormal upper extremity findings out of a total of 22 possibles. The average worker had five to six abnormal findings. Impaired pinch strength, decreased vibration sensitivity in the fingertips, and reports of current numbness were the most prevalent. Of workers with signs, 25% reported no symptoms, whereas only 8% of workers reported symptoms but had no signs. The investigators concluded that this measurement method has utility for assessments of worker populations to determine prevalence of CTDs and, potentially, for preclinical detection of these disorders to permit early intervention, reduce medical costs, and minimize disability. The need for accurate measurement to enhance early detection and prevention is discussed.  相似文献   
105.
106.
This study retrospectively compares patients who underwent outpatient transvaginal follicle aspiration with either a propofol- or methohexital-based intravenous sedation technique. Data collected from patient charts (n = 212) over a 46-month period were analyzed to determine the effects of each sedation technique on procedure and recovery times, number of retrieved ova, as well as rates of nausea, fertilization, cleavage, pregnancy, and delivery. All patients were included in the study, regardless of age or diagnosis. procedure time was lower in the propofol group (51 t 18 min) than in the methohexital group (61 I 20 min) (p > 0.01). Patients in the methohexital group (139 2 51 min) spent more time in the recovery room than did those in the propofol group (71 ? 34 min) (p > 0.01). The nausea rates were significantly lower in the propofol group compared with the methohexital group (1.9% vs. 14.4%, respectively) (p > 0.02). Fertilization rate in the propofol group was 77.7% and was 62.9% in the methohexital group (p > 0.01). The numbers of retrieved ova and the cleavage rates were similar in both groups. The rate of pregnancy in patients sedated with propofol (46.1%) was higher than the methohexital group (26.9%) (p > 0.02). Delivery rate was 38.5% in the propofol group and 20.6% in the methohexital group (p > 0.02). In summary, propofol intravenous sedation for transvaginal follicle aspiration was associ- ated with an improved outcome. Pregnancy and delivery rates were higher while nausea, an unpleasant side effect, was sharply reduced.  相似文献   
107.
108.
We have earlier introduced a principle for learning metrics, which shows how metric-based methods can be made to focus on discriminative properties of data. The main applications are in supervising unsupervised learning to model interesting variation in data, instead of modeling all variation as plain unsupervised learning does. The metrics are derived by approximations to an information-geometric formulation. In this paper, we review the theory, introduce better approximations to the distances, and show how to apply them in two different kinds of unsupervised methods: prototype-based and pairwise distance-based. The two examples are self-organizing maps and multidimensional scaling (Sammon's mapping).  相似文献   
109.
110.
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