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   55080篇
  免费   7739篇
  国内免费   129篇
耳鼻咽喉   954篇
儿科学   1928篇
妇产科学   1608篇
基础医学   4847篇
口腔科学   1547篇
临床医学   9894篇
内科学   12701篇
皮肤病学   733篇
神经病学   4419篇
特种医学   1043篇
外国民族医学   1篇
外科学   5320篇
综合类   382篇
现状与发展   2篇
一般理论   49篇
预防医学   8823篇
眼科学   665篇
药学   2561篇
中国医学   44篇
肿瘤学   5427篇
  2024年   183篇
  2023年   1339篇
  2022年   799篇
  2021年   1491篇
  2020年   1762篇
  2019年   1329篇
  2018年   2162篇
  2017年   1959篇
  2016年   2229篇
  2015年   2268篇
  2014年   3225篇
  2013年   4164篇
  2012年   3663篇
  2011年   3757篇
  2010年   2763篇
  2009年   3015篇
  2008年   3338篇
  2007年   3150篇
  2006年   3391篇
  2005年   2979篇
  2004年   2705篇
  2003年   2359篇
  2002年   2249篇
  2001年   505篇
  2000年   435篇
  1999年   516篇
  1998年   747篇
  1997年   578篇
  1996年   487篇
  1995年   395篇
  1994年   365篇
  1993年   316篇
  1992年   238篇
  1991年   202篇
  1990年   198篇
  1989年   184篇
  1988年   154篇
  1987年   131篇
  1986年   141篇
  1985年   136篇
  1984年   142篇
  1983年   116篇
  1982年   107篇
  1981年   110篇
  1980年   86篇
  1979年   53篇
  1978年   45篇
  1977年   55篇
  1976年   34篇
  1975年   40篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
Since the mid-1970s, the Margaret Sanger Center of Planned Parenthood of New York City has prepared nurses and nurse midwives from less developed countries to be family-planning nurse practitioners. These nurse practitioners then provide services to patients, train other staff, and manage integrated family-planning clinics. More than 120 nurses and nurse midwives have arrived in groups of 10 at the Sanger Center, with 72 attending since 1981. Each course lasts 10 weeks. The core curriculum provides trainees with skills in women's health care including contraception, in training and advocacy, and in management of clinics. Whether, in the current period of scarce resources, cross-cultural training programs of this type remain a worthwhile investment, and if so, which of their components are most important to this success, is assessed.  相似文献   
73.
PurposeThe first purpose was to identify barriers to physical activity that students in grade seven through first-year university experienced. A second purpose was to classify barriers using an ecological framework and to examine the pattern of barrier categories (i.e., intrapersonal, interpersonal, institutional, community, public policy, and physical environmental) and specific barrier types as grade increased. The use of an ecological model addressed limitations in prior research revolving around the identification of salient barriers in a manner that makes the design of effective interventions difficult.MethodsParticipants in grades 7–8 (n = 35), 9–10 (n = 67), 11–12 (n = 80), and the freshmen year of university (n = 109) listed barriers to physical activity on an open-ended measure.ResultsFindings revealed a trend for the average number of barriers reported per student to increase as grade in school increased. First-year university students reported significantly more barriers than all other grade groupings. The frequency of barriers reported within the ecological categories was dependent on the specific grade groupings. Further, within each ecological category, distinct barriers were reported across the different grade groupings.ConclusionsFindings highlight the utility of using an ecological model to categorize barriers, rather than simply classifying barriers as internal or external to an individual, as done in prior research. Understanding the pattern of ecologically based barrier categories and specific types of barriers will help to inform the content of future research and interventions designed to alleviate salient barriers to physical activity.  相似文献   
74.
75.
76.
Background. Accepted practices of informed consent often result in suboptimal patient understanding of research studies.Methods. This pilot study aimed to assess trial-specific tailored materials, compared to a widely used generic booklet about clinical trials, randomly assigned to 118 candidates for cancer clinical trials. Study outcomes were: satisfaction with decision-making; satisfaction with materials; and subjective understanding of the clinical trial.Results. There were no major differences between groups. Participants rated tailored materials higher as a useful reference.Conclusions. Trial-specific materials hold utility for reference during clinical trials. Studies of informed consent are feasible, although important factors limit research.  相似文献   
77.
Short-chain alkyl esters of L-dopa were administered to rats and mice via oral and rectal routes. Plasma L-dopa esters and L-dopa were determined in the systemic and portal circulation by HPLC. A comparison of isopropyl, butyl, and 4-hydroxybutyl esters of L-dopa demonstrated significantly higher levels of the esters in both systemic and portal blood samples following rectal administration than following oral administration. In most cases, oral administration resulted in nondetectable (<0.01 µg/ml) levels of the esters in plasma. Correspondingly, the plasma levels of L-dopa itself were consistently higher following rectal administration. At very high oral doses (500 mg L-dopa equivalents/kg body weight), systemic plasma levels of the butyl ester could be detected (1.25 µg/ml at 10 min), which might indicate saturation of the esterase activity of the small intestine. These studies indicate that the systemic availability of L-dopa from short-chain alkyl esters of L-dopa may be best optimized by rectal administration, which avoids the relatively high esterase activity characteristic of the small intestine.  相似文献   
78.
Rasmussen and Milner [N.Y. Acad. Sci. Vol. 299, pp. 355–379, 1977] published data on late-lesioned (after age 6) epileptic patients who had suffered left hemisphere lesions. They estimated that left hemisphere dominance occurred in 96% of dextrals and 70% of sinistrals. These figures have been regarded as valid estimates for normal dextrals and sinistrals. We administered the Bilateral Object Naming Latency Task, a verbal tachistoscopic task with very good psychometric properties, to 188 dextral and 72 sinistral normals. Results showed that 93.6% of the dextrals and 80.3% of the sinistrals were left hemisphere dominant. A consideration of results from a number of carefully conducted dichotic listening studies suggests, as do present results, that the 70% left-dominance estimate of Rasmussen and Milner for normal sinistrals may be too low by about 10%. It is suggested that ‘bilateral dominance’, present in 15% of the epileptic sinistrals of Rasmussen and Milner, may be much less common in normal sinistrals.  相似文献   
79.
This article reviews the primary health problems of African-American, Hispanic-American, Asian/Pacific Islander-American, and Native-American elders. The goal is to familiarize practicing dietitians with the differences in longevity, disease spectrum, and functional status (where data are available) for each of these ethnic groups. These data should be of assistance in making decisions regarding dietary counseling for ethnic elders. It is acknowledged that most data accumulated according to race do not accurately measure ethnicity. The degree of acculturation may vary widely among individuals. Therefore, it is recommended that dietitians solicit clients’ perceptions of the factors that may contribute to illness and the barriers to implementing recommended remedies.  相似文献   
80.
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