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   8665篇
  免费   776篇
  国内免费   51篇
耳鼻咽喉   70篇
儿科学   309篇
妇产科学   272篇
基础医学   1069篇
口腔科学   379篇
临床医学   768篇
内科学   1685篇
皮肤病学   113篇
神经病学   1023篇
特种医学   492篇
外科学   1153篇
综合类   143篇
一般理论   9篇
预防医学   896篇
眼科学   162篇
药学   563篇
中国医学   5篇
肿瘤学   381篇
  2022年   75篇
  2021年   150篇
  2020年   112篇
  2019年   136篇
  2018年   135篇
  2017年   120篇
  2016年   130篇
  2015年   140篇
  2014年   207篇
  2013年   303篇
  2012年   365篇
  2011年   393篇
  2010年   214篇
  2009年   272篇
  2008年   372篇
  2007年   439篇
  2006年   381篇
  2005年   399篇
  2004年   363篇
  2003年   352篇
  2002年   336篇
  2001年   272篇
  2000年   283篇
  1999年   272篇
  1998年   115篇
  1997年   100篇
  1996年   101篇
  1995年   111篇
  1994年   79篇
  1993年   89篇
  1992年   200篇
  1991年   175篇
  1990年   161篇
  1989年   127篇
  1988年   144篇
  1987年   137篇
  1986年   156篇
  1985年   140篇
  1984年   127篇
  1983年   98篇
  1982年   74篇
  1980年   59篇
  1979年   94篇
  1978年   70篇
  1975年   64篇
  1974年   70篇
  1973年   58篇
  1972年   60篇
  1969年   59篇
  1968年   56篇
排序方式: 共有9492条查询结果,搜索用时 15 毫秒
991.
It is thought that senescence of the immune system is responsible, at least in part, for many health problems associated with ageing. Previous studies on changes in lymphocyte composition have used flow cytometry to study peripheral blood lymphocytes (PBL's), or cells isolated from rodent tissue, and have yielded conflicting results. We have used immunohistochemistry to determine whether the B and T cells in human tissue from spleen and gut are affected by age. Areas of germinal centre, mantle zone and marginal zone of B cell follicles were measured. In addition, CD4 and CD8 T cells in T cell areas and in B cell follicles were counted. We observed a striking age-related decrease in the proportion of CD8+ T cells in the T cell zones of the spleen. This decrease was not apparent in the T cell population that occupies splenic B cell areas, or in GALT. Further differences, in CD4+ cells, were seen between T cell populations in the T cell zones and those in B cell areas. These findings highlight differences between lymphocyte populations in different lymphoid tissues, and different compartments within each tissue, which may be of importance in future studies of the ageing immune system.  相似文献   
992.
Periarteritis in a beagle colony   总被引:1,自引:0,他引:1  
Primary periarteritis, an uncommon necrotizing vasculitis in the dog, was found to affect, almost exclusively, the major branches of the coronary arteries in a number of young beagle dogs. The arteritis was mainly distributed in the proximal segment of the right coronary artery. Immunocytochemical studies failed to identify immunoglobulin deposits in the lesions and the cause of the arteritis remains unknown. It is important to be aware of this spontaneous condition and its regional distribution since certain cardiovascular drugs may also produce necrotizing arteritis at similar sites.  相似文献   
993.
Malignancies in bladder augmentations and intestinal conduits   总被引:12,自引:0,他引:12  
  相似文献   
994.
995.
To investigate change in oral health in relation to use of dental services, a random sample of 45‐ to 54‐yr‐old subjects from Adelaide, South Australia, was surveyed in 2004–2005 (= 986, response rate = 44.4%). Service use and a global oral‐health transition (GOHT) statement were collected over 2 yr. Worsening in oral health was reported from the GOHT statement by 25% of persons, while improvement was reported by 30%. Prevalence ratios (PRs, 95% CI), adjusted for sex, education, health card status, and toothbrushing, showed that worsening oral health was inversely associated with dental visiting (PR = 0.5, 0.4–0.7) and with scaling and cleaning services (PR = 0.6, 0.4–0.9), whereas extractions (PR = 2.3, 1.6–3.4) and dentures (PR = 2.2, 1.3–3.7) were associated with a higher prevalence of worsening. Scaling and cleaning services were associated with improvement in oral health (PR = 1.5, 1.01–2.3), while endodontic services were inversely associated with improvement (PR = 0.3, 0.1–0.9). Worsening in oral health was associated with extractions and dentures and was inversely associated with visiting and preventive care. Improvement in oral health was associated with preventive care and was inversely associated with endodontic treatment.  相似文献   
996.
Surgery for achalasia cardiae: the Dor operation.   总被引:2,自引:0,他引:2       下载免费PDF全文
This review describes our use of the Dor operation in the management of 22 patients with achalasia of the cardia over the period 1970 to 1989. There was a male to female ratio of 1.8:1. All presented with dysphagia of varying degree, with regurgitation (86%), weight loss (73%), pain (59%) and chest infections (14%) being associated symptoms. Two patients had undergone previous balloon dilatation, with temporary benefit. The morbidity was low and follow-up results were good in 94% of cases. None of the patients had symptoms of gastro-oesophageal reflux in the postoperative period. In our experience, the Dor modification of the Heller operation has yielded gratifying results.  相似文献   
997.
Objectives Middle-aged and older adults are retaining teeth and avoiding dentures, which should impact quality of life. The aims of our study were to investigate tooth loss and chewing ability and their association with oral- and general-health-related quality of life and life satisfaction. Methods A random sample of 45- to 54-year-olds from Adelaide, South Australia, was surveyed by self-complete questionnaire in 2004–2005 (n = 879, response rate = 43.8%). Health-related quality of life was measured with the Oral Health Impact Profile 14-item version and EuroQol Visual Analogue Scale instruments and life satisfaction by the Satisfaction with Life Scale. Functional tooth units were recorded at oral examinations performed by calibrated dentists on 709 persons (completion rate = 80.7%). Results Number of functional teeth was positively associated with chewing ability (β = 0.31, P < 0.01). In multivariate analyses, controlling for number of functional teeth and other explanatory variables spanning dental visit pattern, dental behaviour, socio-demographics and socio-economic status, chewing ability was negatively associated with oral-health-related impacts (β = −0.37, P < 0.01) and positively associated with general health (β = 0.10, P < 0.05) and well-being (β = 0.16, P < 0.01). Conclusions Chewing ability was related to oral-health-related quality of life and general health, possibly reflecting the impact of chewing on food choice and enjoyment of meals and diet, and also indicated the importance of oral health to general well-being.  相似文献   
998.
Written primarily by a recent pharmacy school graduate, this commentary aims to express the perceptions about pharmacy faculty members and course evaluations that students often hold. Colleges and schools of pharmacy use many different systems to administer and assess evaluations. While there are numerous published articles regarding these forms of evaluation, almost no literature exists that reflects the opinions of those actually completing the evaluations, ie, students. Explaining the purpose of evaluations and how they will be used, how to correctly complete evaluations, and the potential responsiveness of and receptivity of professors, as well as other factors, impact how students perceive and complete their evaluations. It is worthwhile to gather students’ perspectives on evaluations as these assessments hold the potential to drive curricular change and faculty promotion. Considering students perspectives can help colleges and schools design and administer more effective evaluations, increasing the utility of these assessments.  相似文献   
999.
1000.
Genome-wide association studies (GWAS) are a powerful tool for understanding the genetic basis of diseases and traits, but most studies have been conducted in isolation, with a focus on either a single or a set of closely related phenotypes. We describe MetABF, a simple Bayesian framework for performing integrative meta-analysis across multiple GWAS using summary statistics. The approach is applicable across a wide range of study designs and can increase the power by 50% compared with standard frequentist tests when only a subset of studies have a true effect. We demonstrate its utility in a meta-analysis of 20 diverse GWAS which were part of the Wellcome Trust Case Control Consortium 2. The novelty of the approach is its ability to explore, and assess the evidence for a range of possible true patterns of association across studies in a computationally efficient framework.  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