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   3218799篇
  免费   255252篇
  国内免费   7520篇
耳鼻咽喉   45452篇
儿科学   101459篇
妇产科学   86685篇
基础医学   460423篇
口腔科学   92464篇
临床医学   302651篇
内科学   620057篇
皮肤病学   64942篇
神经病学   270846篇
特种医学   125119篇
外国民族医学   1128篇
外科学   471719篇
综合类   76343篇
现状与发展   2篇
一般理论   1361篇
预防医学   268911篇
眼科学   74915篇
药学   240734篇
  10篇
中国医学   6505篇
肿瘤学   169845篇
  2018年   34754篇
  2017年   26564篇
  2016年   29066篇
  2015年   33096篇
  2014年   47021篇
  2013年   72361篇
  2012年   98220篇
  2011年   103920篇
  2010年   60964篇
  2009年   57621篇
  2008年   97436篇
  2007年   103581篇
  2006年   104422篇
  2005年   101417篇
  2004年   97137篇
  2003年   93415篇
  2002年   91592篇
  2001年   144599篇
  2000年   149455篇
  1999年   126432篇
  1998年   37233篇
  1997年   33784篇
  1996年   33216篇
  1995年   32101篇
  1994年   30137篇
  1993年   28214篇
  1992年   102224篇
  1991年   99306篇
  1990年   96197篇
  1989年   92258篇
  1988年   85730篇
  1987年   84297篇
  1986年   80188篇
  1985年   76630篇
  1984年   58250篇
  1983年   49714篇
  1982年   30261篇
  1981年   26934篇
  1979年   54331篇
  1978年   38435篇
  1977年   32133篇
  1976年   30613篇
  1975年   32085篇
  1974年   39423篇
  1973年   37948篇
  1972年   35356篇
  1971年   32798篇
  1970年   30662篇
  1969年   28360篇
  1968年   26239篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
G. Berlin  M. Hammar  L. Tapper 《Platelets》2019,30(4):473-479
Platelets are needed to prevent or arrest bleeding and aggregate at the site of injury upon vascular damage. Platelets express receptors for estrogens which might affect the function of the platelets and their hemostatic ability. The aim was to identify possible differences in platelet function related to age, gender, and phases of the menstrual cycle by use of impedance aggregometry with Multiplate. In the first part of the study, platelet function was assessed in 60 healthy individuals (30 men and 30 women) in each of three age groups (20–25, 40–45, and 60–65 years). In the second part of the study, the platelet function was analyzed on four occasions during the menstrual cycle in women without oral contraceptives (OCs) (n = 17) and compared to 19 women on OCs and 18 men of similar age (20–40 years). For the women on OCs, aggregation was analyzed once during the tablet-free week and once late during the period with OCs. The men were sampled once. Women of younger age (<45 years) had significantly higher agonist-induced aggregation response than both men and post-menopausal women (60–65 years). The agonist-induced aggregation response did not differ between phases of the menstrual cycle or OC use. The results suggest that estradiol and/or progesterone affect spontaneous aggregation since it was found to be lowest in the mid-luteal phase. Spontaneous aggregation was significantly lower in women on OCs than in both men and women without OCs. Our findings indicate that fertile age is associated with higher aggregation response capacity of the platelets, possibly to prevent excessive bleeding during menstruation, but this response capacity is not altered during the menstrual cycle or by use of OCs.  相似文献   
52.
53.
54.
55.
56.
Academic output is just one aspect of a successful career as a plastic surgeon. However, for those with a strong interest in academia, the academic output of a department will likely be a key factor when deciding how to rank jobs. The aim of this study was to quantify and rank the academic output of plastic surgery units across the UK and Ireland. The Institute for Scientific Information (ISI) Web of Science Bibliometric analysis tool was used to collate cumulative (1950–2016), 10 year (2006–2016) and 3 years (2013–2015) research output data for plastic surgery units in the UK and Ireland. Sixty-six plastic surgery units were identified. Departments were ranked for each time period according to the number of papers produced, number of citations (Nc) and h-index (a measure of the impact of scientific output). The top 3 departments for number of papers in the last 10 years were The Royal Free Hospital, London (226) Broomfield Hospital, Chelmsford (218), and Morriston Hospital and Swansea (188). The top 3 for h-number were The Royal Free Hospital (21) Wythenshawe Hospital, Manchester (18) and Morriston Hospital (17). Academic output varies across plastic surgery units in the UK and Ireland. A number of departments have consistently maintained high academic outputs across the years and will be of interest to surgeons hoping to pursue a career in academia.  相似文献   
57.
58.
Monitoring variations in the functioning of the autonomic nervous system may help personalize training of runners and provide more pronounced physiological adaptations and performance improvements. We systematically reviewed the scientific literature comparing physiological adaptations and/or improvements in performance following training based on responses of the autonomic nervous system (ie, changes in heart rate variability) and predefined training. PubMed, SPORTDiscus, and Web of Science were searched systematically in July 2019. Keywords related to endurance, running, autonomic nervous system, and training. Studies were included if they (a) involved interventions consisting predominantly of running training; (b) lasted at least 3 weeks; (c) reported pre- and post-intervention assessment of running performance and/or physiological parameters; (d) included an experimental group performing training adjusted continuously on the basis of alterations in HRV and a control group; and (e) involved healthy runners. Five studies involving six interventions and 166 participants fulfilled our inclusion criteria. Four HRV-based interventions reduced the amount of moderate- and/or high-intensity training significantly. In five interventions, improvements in performance parameters (3000 m, 5000 m, Loadmax, Tlim) were more pronounced following HRV-based training. Peak oxygen uptake () and submaximal running parameters (eg, LT1, LT2) improved following both HRV-based and predefined training, with no clear difference in the extent of improvement in . Submaximal running parameters tended to improve more following HRV-based training. Research findings to date have been limited and inconsistent. Both HRV-based and predefined training improve running performance and certain submaximal physiological adaptations, with effects of the former training tending to be greater.  相似文献   
59.
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