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   6957篇
  免费   478篇
  国内免费   16篇
耳鼻咽喉   30篇
儿科学   204篇
妇产科学   157篇
基础医学   1194篇
口腔科学   79篇
临床医学   796篇
内科学   1332篇
皮肤病学   191篇
神经病学   593篇
特种医学   186篇
外科学   606篇
综合类   106篇
一般理论   4篇
预防医学   879篇
眼科学   173篇
药学   339篇
中国医学   17篇
肿瘤学   565篇
  2023年   55篇
  2022年   74篇
  2021年   174篇
  2020年   94篇
  2019年   128篇
  2018年   165篇
  2017年   131篇
  2016年   153篇
  2015年   176篇
  2014年   228篇
  2013年   342篇
  2012年   441篇
  2011年   533篇
  2010年   287篇
  2009年   263篇
  2008年   449篇
  2007年   411篇
  2006年   430篇
  2005年   463篇
  2004年   382篇
  2003年   369篇
  2002年   326篇
  2001年   97篇
  2000年   71篇
  1999年   75篇
  1998年   70篇
  1997年   60篇
  1996年   56篇
  1995年   45篇
  1994年   44篇
  1993年   52篇
  1992年   49篇
  1991年   49篇
  1990年   45篇
  1989年   50篇
  1988年   40篇
  1987年   41篇
  1986年   29篇
  1985年   41篇
  1984年   39篇
  1983年   27篇
  1982年   30篇
  1981年   28篇
  1980年   24篇
  1979年   22篇
  1978年   22篇
  1976年   27篇
  1975年   29篇
  1974年   22篇
  1973年   18篇
排序方式: 共有7451条查询结果,搜索用时 31 毫秒
31.
32.
Here we present the results of a study performed on 59 patients affected by Waardenburg syndrome (WS), 30 with the I variant, 21 having the type II, and 8 of them being isolated cases without telecanthus. These patients belong to 37 families; the main contributions and conclusions are based on the detailed study of 25 of these families, examined using standard procedures. All patients were examined as to the presence of eight cardinal signs important for the diagnosis of the condition; from each patient, from many of his/her normal relatives, and from a control sample of 300 normal individuals stratified by age and sex, 23 different craniofacial measurements were obtained. We also estimated, using our own data as well those collected from the literature, the frequencies of the cardinal signs, based on a total sample of 461 affected individuals with WSI and 121 with WSII. In order to originate discriminant functions to separate individuals affected by one of the two variants, both metric (from craniofacial measurements) as well as categoric data (based on the frequencies of the cardinal signs or symptoms) were used. Discriminant analysis based on the frequency of the eight cardinal signs can improve the separation of WSI patients without telecanthus from those presenting the variant II. We present also a Table with the conditional probabilities favoring the diagnosis of WSI for suspect subjects without telecanthus and any combination of the other seven signs/symptoms. The discriminant function based on the four ocular measurements (inner and outer intercanthal, interpupillary, and inferior lacrymal distances), on the other side, perfectly classifies patients affected by one of the variants of WS, the same taking place when the average values of the W index of all affected individuals per family are used. The discriminant function based solely in the individual W index values of patients correctly classifies 93% of WSII subjects, but only 60% of the patients with the I variant of WS.  相似文献   
33.
NOV, located on human chromosome 8q24.1, was originally cloned following discovery of its avian homolog as a consequence of over-expression in virally induced nephroblastoma. The gene product is a secreted, modular, protein and a member of the CCN gene family. Evidence to date indicates that the expression of the wild type protein is associated with cellular quiescence in normal embryonic fibroblasts yet produces growth stimulatory effects on established murine NIH 3T3 cells. Here we report the expression of NOV in the first trimester of human embryogenesis, between 5 and 10 weeks. In situ hybridisation and immunohistochemistry reveal widespread expression in derivatives of all three germ layers. The most abundant sites of expression are in the motor neurons and floor plate of the spinal cord, adrenal cortex, fusing skeletal, and smooth muscle, the urogenital system and the developing heart. Additionally, expression is seen in the cranial ganglia, differentiating chondrocytes, gonads, and lung. The sites of expression suggest strongly that autocrine or paracrine expression of NOV is associated with the process of cell differentiation.  相似文献   
34.
35.
36.
Disclosure of the results of a positive genetic mutation to offspring can be challenging. The purpose of this study was to investigate the content and process of disclosure from BRCA1/2 carriers to their offspring. A semi-structured questionnaire focused on the disclosure processes between parent and offspring. Thirty-one/40 mothers with BRCA1/2 mutations completed the cross-sectional survey. Sixteen carriers (51.6%) chose to disclose their results to all of their children, thirteen carriers (41.9%) chose not to disclose their results, and two carriers (6.5%) chose to disclose to some of their children. The age of a child appeared to be the most significant contributing factor in the decision to disclose. The mean age of the offspring who learned of the positive test result was 24.3 years with most carriers advocating the ideal age range for disclosure from 19 to 25 years. There was a discrepancy between actual and potential disclosure topics between those who had disclosed and those who had not disclosed at the time of the survey. Women who disclosed their result tended to do so alone, within a week of learning their own results, equally to male and female offspring and expressed that the relationships between themselves and their children had strengthened since revealing the presence of a genetic mutation in the family. Women who had not disclosed the results of their genetic test to offspring were significantly more interested in receiving additional individual counseling, educational videos, and email newsletters that focus on disclosure of this complex and life altering information compared to those who had already disclosed. Disclosure of BRCA1/2 results is determined primarily by age of offspring, is usually done by women alone, relatively soon after receiving results and appears to enhance the relationships between mothers and offspring. Both disclosed and non-disclosed carriers demonstrated significant interest in a variety of interventions to support the disclosure process.  相似文献   
37.
38.
39.
40.
Background: To evaluate the potential factors associated with the nutritional composition of human milk of puerperal women. Methods: cross-sectional study, conducted between March 2016 and August 2017, with 107 women, selected in a Tertiary Health Care Tertiary Health Facility of the Unified Health System (SUS) in the Municipality of Rio de Janeiro. Data were collected two months after delivery. The dependent variable of the study was the nutritional composition of human milk. We divided the independent variables into hierarchical levels: distal (age, schooling, parity and pregestational nutritional status), intermediate (number of prenatal visits and gestational weight gain) and proximal (alcohol consumption, smoking, diabetes mellitus and hypertension). For data analysis, we applied the multiple linear regression, centered on the hierarchical model. Only the variables associated with the nutritional composition of breast milk remained in the final model at a 5% level of significance. Results: The nutritional composition of human milk yielded by women with pregestational overweight, smokers and hypertensive had higher amounts of lipids and energy. Conversely, women with gestational weight gain below the recommended had lower amounts of these components. Conclusion: The evaluation of factors associated with the nutritional composition of human milk is extremely important to assist post-partum care practices. In this study, we observed that lipid and energy contents were associated to pregestational nutritional status, gestational weight gain, smoking and hypertension.  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