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   20117篇
  免费   1807篇
  国内免费   40篇
耳鼻咽喉   105篇
儿科学   622篇
妇产科学   547篇
基础医学   2910篇
口腔科学   293篇
临床医学   2614篇
内科学   3899篇
皮肤病学   443篇
神经病学   1929篇
特种医学   873篇
外科学   2526篇
综合类   614篇
一般理论   15篇
预防医学   1672篇
眼科学   265篇
药学   1307篇
中国医学   15篇
肿瘤学   1315篇
  2021年   309篇
  2020年   216篇
  2019年   321篇
  2018年   373篇
  2017年   304篇
  2016年   286篇
  2015年   307篇
  2014年   450篇
  2013年   673篇
  2012年   939篇
  2011年   909篇
  2010年   520篇
  2009年   506篇
  2008年   871篇
  2007年   906篇
  2006年   909篇
  2005年   822篇
  2004年   834篇
  2003年   792篇
  2002年   680篇
  2001年   686篇
  2000年   721篇
  1999年   630篇
  1998年   257篇
  1997年   205篇
  1996年   222篇
  1995年   202篇
  1994年   196篇
  1993年   182篇
  1992年   471篇
  1991年   455篇
  1990年   424篇
  1989年   389篇
  1988年   382篇
  1987年   407篇
  1986年   377篇
  1985年   380篇
  1984年   301篇
  1983年   258篇
  1982年   169篇
  1981年   163篇
  1980年   143篇
  1979年   244篇
  1978年   200篇
  1977年   145篇
  1975年   116篇
  1974年   166篇
  1973年   163篇
  1972年   152篇
  1971年   133篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
This paper identifies the need for more specific guidelines in preparing faculty to use and develop computer-based instructional materials. Cory's model for faculty development is described and planning considerations are outlined. Finally, components of this multifaceted approach to faculty development—identifying available resources, emphasizing the current uses of computers, providing computer literacy/faculty awareness sessions, focusing on the instructional use of microcomputers, collaboration, and communication—are discussed.  相似文献   
43.
Birthweight-specific admission rates were reviewed from 1974 to 1982 for Georgia's five regional perinatal centers. Analysis of birthweight-specific neonatal intensive care unit (NICU) admissions as a proportion of total live births revealed an upward trend for infants weighing 1,000 to 1,499 gm and a downward trend for those weighing 2,000 gm or more. This method revealed no significant trends for infants of weight groups less than 500 gm or 500 to 999 gm. Analysis of birthweight-specific admissions as a proportion of total NICU admissions revealed significant increases for all birthweight groups of less than 2,000 gm, with decreases in admissions for infants weighing more than 2,000 gm. Analysis of mortality data revealed improved survival for infants weighing less than 1,500 gm, but some centers showed increases in neonatal mortality, postneonatal mortality, or infant mortality among infants weighing 2,500 gm or more. During this study, low birthweight infants comprised an increasingly larger proportion of neonatal intensive care admissions. This trend evolved gradually through the process of regionalization and can be directly linked to the cost requirements of regional neonatal intensive care units.  相似文献   
44.
45.
Choice of a childbirth method after cesarean   总被引:1,自引:0,他引:1  
Concern about the rising cesarean-section rate and the high percentage of elective repeat cesareans led to an exploratory, retrospective examination of women's decision-making about a childbirth method after cesarean. Fifty women who had delivered by a repeat cesarean (RC) or vaginal birth after cesarean (VBAC) participated in a telephone interview. Three questions were addressed: (1) who made the decision for a birth method; (2) what factors were associated with the choice of method; and (3) was the choice of method associated with the actual method of delivery? The majority of women (90%) perceived that they were the primary decision-maker for a birth method, and choice of birth method was positively associated with actual method of delivery. The major reason for VBAC choice was to experience a vaginal birth, whereas the primary reason for RC choice was to avoid an unsuccessful labor. Other factors associated with choice of a birth method were: sources of information and support, beliefs, previous cesarean experience and locus of control. These findings have important implications for enhancing women's health-care decision-making, as well as for reducing the rate of repeat-cesarean deliveries.  相似文献   
46.
47.
OBJECTIVE: To investigate peripheral nasal pathology as a contributor to olfactory impairment in DS. STUDY DESIGN: Twenty DS and 16 non-DS subjects were recruited. Nasal history and symptoms were assessed by self-report or informant. Olfactory threshold, odor identification, and nasal endoscopy were assessed on each subject. RESULTS: DS subjects were impaired on olfactory threshold (P<0.0001) and odor identification (P<0.001). Although DS subjects tended toward upper-respiratory infections, sleep-disordered breathing, and nasal itching, differences were not significant (P=0.07, 0.06, and 0.058, respectively). There were no significant differences on self-reported nasal history or symptoms. Endoscopy showed equivalent health in DS and control subjects. CONCLUSION: This DS population shows olfactory impairment. However, nasal health is comparable in DS subjects and controls. Nasal dysfunction is unlikely to contribute to olfactory impairment in DS. SIGNIFICANCE: Olfactory deficits in DS appear to be secondary to central, rather than rhinologic, pathology. EBM rating: B-2b.  相似文献   
48.
The relation of dizziness to functional decline   总被引:2,自引:0,他引:2  
OBJECTIVE: to assess the effect of dizziness on the probability that an older person will die or become functionally disabled within 2 years. Dizziness is a common symptom for which the prognosis is uncertain. This report compares the prognoses for dizzy and not-dizzy older people in order to assist clinicians who diagnose and treat these patients. DESIGN: a prospective study of a representative sample of elderly (70+) non-institutionalized Americans. Elderly subjects (n = 3,798) in the Longitudinal Study of Aging (LSOA) were asked questions about the presence of dizziness, medical conditions, and functional disability in 1984. The cohort was reinterviewed about functional disability in 1986. OUTCOME MEASURE: transition from functional ability to disability after 2 years. RESULTS: Bivariate analyses showed that dizziness predicts functional decline but not mortality. Multivariate models revealed that age, race, sensory impairment, vascular disease, and other morbidity are independent predictors of becoming disabled. Controlling for these potential confounders, dizziness does not predict an increased probability of becoming disabled. CONCLUSION: Elderly people who are dizzy should be evaluated for the presence of these related conditions.  相似文献   
49.
The current study evaluated psychosocial variables that may contribute to the experience of headache in college adults. One hundred ninety-nine participants, 103 women and 96 men, completed head pain logs for 4 weeks after completing measures assessing psychosocial variables. Multiple regression analyses indicated that level of emotional functioning, perception of stress, and gender were predictive of future headache frequency, intensity, and duration. Family history and health habits did not predict headache activity. These findings are consistent with research investigating psychosocial variables and headache activity.  相似文献   
50.
An orthotopic model of human melanoma was developed in which malignant cells were injected into human skin grafted to nude and SCID mice. Melanoma cells proliferated and invaded the human skin grafts with characteristic patterns. Three of six melanomas grew as multiple nodules and infiltered the grafts without major architectural changes in the dermis, whereas the others invaded the dermis along collagen fibers with prominent endothelial vessels. By contrast, melanoma cells inoculated into mouse skin grew as diffusely expanding nodules that did not invade the murine dermis. In human skin grafts, human melanoma cells were angiogenic for human blood vessels, and murine vessels were only found at the periphery of grafts. Tumor cells invaded the human vessels, and four out of seven cell lines metastasized to lungs, suggesting that this model is useful to determine in vivo the interactions between normal and malignant human cells.  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