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   3522548篇
  免费   259823篇
  国内免费   9450篇
耳鼻咽喉   48185篇
儿科学   117050篇
妇产科学   98453篇
基础医学   496031篇
口腔科学   98126篇
临床医学   321764篇
内科学   689252篇
皮肤病学   84133篇
神经病学   290916篇
特种医学   135884篇
外国民族医学   1127篇
外科学   527578篇
综合类   74790篇
现状与发展   7篇
一般理论   1352篇
预防医学   272040篇
眼科学   80539篇
药学   255457篇
  8篇
中国医学   7501篇
肿瘤学   191628篇
  2021年   27371篇
  2019年   28383篇
  2018年   40294篇
  2017年   30987篇
  2016年   35921篇
  2015年   40414篇
  2014年   55583篇
  2013年   83304篇
  2012年   111738篇
  2011年   118078篇
  2010年   70720篇
  2009年   67099篇
  2008年   109887篇
  2007年   116890篇
  2006年   118737篇
  2005年   114789篇
  2004年   109934篇
  2003年   106199篇
  2002年   102577篇
  2001年   167574篇
  2000年   171582篇
  1999年   144489篇
  1998年   42078篇
  1997年   37375篇
  1996年   37265篇
  1995年   36010篇
  1994年   32853篇
  1993年   30738篇
  1992年   110985篇
  1991年   106598篇
  1990年   103369篇
  1989年   99553篇
  1988年   91319篇
  1987年   89450篇
  1986年   83808篇
  1985年   80216篇
  1984年   60181篇
  1983年   51044篇
  1982年   30588篇
  1979年   53429篇
  1978年   37838篇
  1977年   31893篇
  1976年   29687篇
  1975年   31483篇
  1974年   37388篇
  1973年   35733篇
  1972年   33613篇
  1971年   31123篇
  1970年   28891篇
  1969年   27549篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
ABSTRACT

This project examined 55 picture books featuring transgender, gender expansive or genderqueer protagonists or narrators published between 2008 and 2018. The purpose of the study was to determine how this genre of children’s literature supports and challenges four gender assumptions: the gender binary, gender essentialism, sex/gender congruency and gender stability. Additionally, this critical analysis explored misgendering within this genre and themes of social rejection and acceptance. Protagonists and narrators were permitted a degree of gender nonconformity, however, the majority of picture books missed opportunities for a more complete exploration of gender possibilities.  相似文献   
62.
63.
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   
64.
65.
Introduction: In men, lower urinary tract symptoms (LUTS) are primarily attributed to benign prostatic hyperplasia (BPH). Therapeutic options are targeted to relax prostate smooth muscle and/or reduce prostate enlargement.

Areas covered: This article reviews the major preclinical and clinical data on PDE5 inhibitors with a specific focus on tadalafil. It includes details of the role of the nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) – PDE5 pathway in the LUT organs (bladder and prostate) in addition to the available data on tadalafil in patients with LUTS secondary to BPH with or without erectile dysfunction (ED).

Expert opinion: Preclinical and clinical data have clearly demonstrated that PDE5 inhibitors induce bladder and prostate relaxation, which contributes to the improvement seen in storage symptoms in both animal models of bladder and prostate hypercontractility. Tadalafil is effective both as a monotherapy and add-on therapy in patients with LUTS secondary to BPH. Furthermore, as LUTS-BPH and ED are urological disorders that commonly coexist in aging men, tadalafil is more advantageous than α1-adrenoceptors and should be used as the first option. Tadalafil is a safe and tolerable therapy and unlike α1- adrenoceptors and 5-alpha reductase inhibitors, which can cause sexual dysfunctions, tadalafil improves sexual function.  相似文献   

66.
67.
68.
69.
There is a sharp difference in how one views TCR structure–function–behaviour dependent on whether its recognition of major histocompatibility complex‐encoded restriction elements (R) is germline selected or somatically generated. The generally accepted or Standard model is built on the assumption that recognition of R is by the V regions of the αβ TCR, which is not driven by allele specificity, whereas the competing model posits that recognition of R is allele‐specific. The establishing of allele‐specific recognition of R by the TCR would rule out the Standard model and clear the road to a consideration of a competing construct, the Tritope model. Here, the case for allele‐specific recognition (germline selected) is detailed making it obvious that the Standard model is untenable.  相似文献   
70.
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