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   71138篇
  免费   5322篇
  国内免费   166篇
耳鼻咽喉   731篇
儿科学   2571篇
妇产科学   1862篇
基础医学   9009篇
口腔科学   961篇
临床医学   11967篇
内科学   12258篇
皮肤病学   814篇
神经病学   6835篇
特种医学   1568篇
外国民族医学   1篇
外科学   6842篇
综合类   832篇
一般理论   114篇
预防医学   9811篇
眼科学   853篇
药学   4214篇
中国医学   73篇
肿瘤学   5310篇
  2023年   496篇
  2022年   689篇
  2021年   1386篇
  2020年   1048篇
  2019年   1692篇
  2018年   1876篇
  2017年   1393篇
  2016年   1540篇
  2015年   1709篇
  2014年   2305篇
  2013年   3644篇
  2012年   5135篇
  2011年   5334篇
  2010年   2901篇
  2009年   2629篇
  2008年   4794篇
  2007年   4933篇
  2006年   4915篇
  2005年   4737篇
  2004年   4395篇
  2003年   4059篇
  2002年   3894篇
  2001年   650篇
  2000年   558篇
  1999年   637篇
  1998年   887篇
  1997年   662篇
  1996年   580篇
  1995年   511篇
  1994年   494篇
  1993年   473篇
  1992年   384篇
  1991年   362篇
  1990年   354篇
  1989年   343篇
  1988年   314篇
  1987年   277篇
  1986年   275篇
  1985年   294篇
  1984年   279篇
  1983年   265篇
  1982年   281篇
  1981年   286篇
  1980年   242篇
  1979年   155篇
  1978年   131篇
  1977年   132篇
  1976年   129篇
  1975年   124篇
  1974年   118篇
排序方式: 共有10000条查询结果,搜索用时 21 毫秒
51.
52.
OBJECTIVES: Diagnostic accuracy of the ThinPrep process (Cytyc, Boxborough, MA) was compared with that of conventional (smear) cytopreparation for fine-needle aspiration (FNA) of head and neck masses. METHODS: In a prospective, randomized, single-blinded study, 209 patients served as their own controls and underwent 236 FNAs using ThinPrep and conventional (smear) cytopreparatory techniques. RESULTS: ThinPrep produced less air-drying artifact and less mechanical distortion than the conventional method. The conventional technique was diagnostic in 63% of samples; the ThinPrep technique was diagnostic in 55% of samples. When all results were combined, pathologists subjectively preferred the conventional technique but accepted use of ThinPrep as the only cytopreparatory technique for most head and neck masses. CONCLUSIONS: For adequately experienced cytopathologists, ThinPrep is acceptable for FNA of salivary masses, neck cysts, metastatic lymph nodes, and thyroid lesions. Conventional smear technique should be used for FNA of nonmetastatic lymphoid lesions. Use of ThinPrep can complement use of the conventional (smear) cytopreparatory technique when aspirate is nondiagnostic or bloody, when the patient has a blood-borne infectious disease, when the clinician is inexperienced, or when aspirate has entered the syringe.  相似文献   
53.
54.
55.
PURPOSE: A role for estrogens in determining lung cancer risk and prognosis is suggested by reported sex differences in susceptibility and survival. Archival lung tissue was evaluated for the presence of nuclear estrogen receptor (ER)-alpha and ER-beta and the relationship between ER status, subject characteristics, and survival. EXPERIMENTAL DESIGN: Paraffin-embedded lung tumor samples were obtained from 214 women and 64 men from two population-based, case-control studies as were 10 normal lung autopsy samples from patients without cancer. Nuclear ER-alpha and ER-beta expression was determined by immunohistochemistry. Logistic regression was used to identify factors associated with ER positivity and Cox proportional hazards models were used to measure survival differences by ER status. RESULTS: Neither tumor (0 of 94) nor normal (0 of 10) lung tissue stained positive for ER-alpha. Nuclear ER-beta positivity was present in 61% of tumor tissue samples (170 of 278; 70.3% in men and 58.3% in women) and 20% of normal tissue samples (2 of 10; P = 0.01). In multivariate analyses, females were 46% less likely to have ER-beta-positive tumors than males (odds ratio, 0.54; 95% confidence interval, 0.27-1.08). This relationship was stronger and statistically significant in adenocarcinomas (odds ratio, 0.40; 95% confidence interval, 0.18-0.89). Women with ER-beta-positive tumors had a nonsignificant 73% (P = 0.1) increase in mortality, whereas men with ER-beta-positive tumors had a significant 55% (P = 0.04) reduction in mortality compared with those with ER-beta-negative tumors. CONCLUSIONS: This study suggests differential expression by sex and influence on survival in men of nuclear ER-beta in lung cancer, particularly in adenocarcinomas.  相似文献   
56.
BACKGROUND: The long-term observation of vegetarians in affluent countries can provide insight into the relative effects of a vegetarian diet and lifestyle factors on mortality. METHODS: A cohort study of vegetarians and health-conscious persons in Germany was followed-up prospectively for 21 years, including 1,225 vegetarians and 679 health-conscious nonvegetarians. Standardized mortality ratios compared with the German general population were calculated for all causes and specific causes. Within the cohort, Poisson regression modeling was used to investigate the joint effects of several risk factors on overall and cause-specific mortality. RESULTS: Standardized mortality ratios for all-cause mortality was significantly below 100: 59 [95% confidence interval (95% CI), 54-64], predominantly due to a deficit of deaths from circulatory diseases. Within the cohort, vegetarian compared with nonvegetarian diet had no effect on overall mortality [rate ratio (RR), 1.10; 95% CI, 0.89-1.36], whereas moderate and high physical activity significantly reduced risk of death (RR, 0.62, 0.64), adjusted for age, sex, smoking, alcohol intake, body mass index, and educational level. Vegetarian diet was however associated with a reduced RR of 0.70 (95% CI, 0.41-1.18) for ischemic heart disease, which could partly be related to avoidance of meat. CONCLUSIONS: Both vegetarians and nonvegetarian health-conscious persons in this study have reduced mortality compared with the general population. Within the study, low prevalence of smoking and moderate or high level of physical activity but not strictly vegetarian diet was associated with reduced overall mortality. The nonsignificant reduction in mortality from ischemic heart diseases in vegetarians compared with health-conscious persons could be explained in part by avoidance of meat intake.  相似文献   
57.
58.
59.
OBJECTIVE: This article 1) provides an overview of formal Health Sciences Teaching Scholars Programs as presented in medical education literature and 2) presents information about an innovative multidiscipline Teaching Scholars Program. METHOD: Health Sciences Teaching Scholars Programs and similar programs were reviewed in the medical education literature to identify similar and dissimilar characteristics. The WVU Teaching Scholars Program highlighted in this article is presented with a discussion of goals, objectives, target audiences, course length, session frequency, program topics, learning methods, and assessments of the programs. A summary of the WVU Teaching Scholars Program and two Teaching Scholars Programs at McGill University and the University of Toronto were presented at the Association for American Medical Colleges (AAMC) annual meeting in 2006 for input from the general medical education audience. RESULTS: Comparisons of Health Sciences Teaching Scholars Programs reveal that successful programs are uniquely shaped by their educational environments. Scholars report that they value learning new teaching methods and improving their educational careers. CONCLUSION: Teaching Scholars Programs are valuable for the development of enhancing both teaching and scholarship in Health Sciences Programs and must adapt to the uniqueness of their respective educational environments and must continue to nurture scholars beyond graduation.  相似文献   
60.
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