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   7789篇
  免费   330篇
  国内免费   48篇
耳鼻咽喉   70篇
儿科学   300篇
妇产科学   458篇
基础医学   1257篇
口腔科学   167篇
临床医学   620篇
内科学   1386篇
皮肤病学   417篇
神经病学   608篇
特种医学   405篇
外科学   927篇
综合类   134篇
一般理论   4篇
预防医学   292篇
眼科学   193篇
药学   389篇
中国医学   1篇
肿瘤学   539篇
  2022年   48篇
  2021年   101篇
  2020年   65篇
  2019年   88篇
  2018年   92篇
  2017年   75篇
  2016年   102篇
  2015年   110篇
  2014年   160篇
  2013年   261篇
  2012年   278篇
  2011年   321篇
  2010年   234篇
  2009年   218篇
  2008年   307篇
  2007年   327篇
  2006年   336篇
  2005年   345篇
  2004年   355篇
  2003年   316篇
  2002年   311篇
  2001年   171篇
  2000年   165篇
  1999年   160篇
  1998年   134篇
  1997年   99篇
  1996年   81篇
  1995年   74篇
  1994年   71篇
  1993年   78篇
  1992年   71篇
  1991年   78篇
  1990年   72篇
  1989年   92篇
  1988年   88篇
  1987年   94篇
  1986年   72篇
  1985年   78篇
  1984年   62篇
  1983年   41篇
  1981年   42篇
  1979年   57篇
  1976年   34篇
  1975年   45篇
  1971年   33篇
  1969年   36篇
  1931年   32篇
  1930年   36篇
  1928年   42篇
  1913年   43篇
排序方式: 共有8167条查询结果,搜索用时 0 毫秒
91.
PurposeEvaluation of mRNA and microRNA (miRNA) expression in epithelium and stroma of patients with keratoconus.MethodsThe epithelium and stroma of eight corneas of eight patients with keratoconus and eight corneas of eight non-keratoconus healthy controls were studied separately. RNA was extracted, and mRNA and miRNA analyses were performed using microarrays. Differentially expressed mRNAs and miRNAs in epithelial and stromal keratoconus samples compared to healthy controls were identified. Selected genes and miRNAs were further validated using RT-qPCR.ResultsWe discovered 170 epithelial and 1498 stromal deregulated protein-coding mRNAs in KC samples. In addition, in epithelial samples 180 miRNAs and in stromal samples 379 miRNAs were significantly deregulated more than twofold compared to controls. Pathway analysis revealed enrichment of metabolic and axon guidance pathways for epithelial cells and enrichment of metabolic, mitogen-activated protein kinase (MAPK), and focal adhesion pathways for stromal cells.ConclusionsThis study demonstrates significant differences in the expression and regulation of mRNAs and miRNAs in the epithelium and stroma of Patients with KC. Also, in addition to the well-known target candidates, we were able to identify further genes and miRNAs that may be associated with keratoconus. Signaling pathways influencing metabolic changes and cell contacts are affected in epithelial and stromal cells of patients with keratoconus.  相似文献   
92.
蓣知子皂甙IV的结构   总被引:5,自引:1,他引:5  
从木通科木通属植物白木通[Akebia trifoliata(Thunb.)Koidz.var.australis(Diels)Rehd]种子的乙醇提取物中以硅胶层析等方法得四种三萜皂甙。其中甙IV是新天然产物,命名为蓣知子皂甙IV(yuzhiziosideIV)。根据化学和光谱分析,确定甙IV的结构为3-O-β-D-吡喃木糖基-(1→2)-a-L-吡喃阿拉伯糖齐墩果酸-28-O-β-D-吡喃葡萄糖基-(1→6)-β-D-吡喃葡萄糖酯甙。另外皂甙B(I)、皂甙C(II)和皂甙D(III)为已知物。这些化合物在白木通种子中均是首次得到。  相似文献   
93.
There are only scarce data on the incidence of spontaneous pregnancy in infertility patients. Contraception after infertility treatment is another topic that has been neglected so far. Therefore, a questionnaire was sent to 1614 couples with a child conceived by intracytoplasmic sperm injection (ICSI) aged 4-6 years. A total of 899 couples responded (response rate 55.7%). A total of 10.9% of couples had used contraception. Of the couples that had actively tried to conceive, 20.0% had conceived spontaneously, resulting in a live-birth rate of 16.4%. 74.5% of these pregnancies were conceived within 2 years after delivery. A further 26.6% of couples conceived again by ICSI, with a live-birth rate of 20.9%. Maternal age was the only prognostic factor for spontaneous conception. Parents of multiples after ICSI did not have a higher chance of spontaneous conception than parents of singletons. Couples can be counselled that one out of five couples conceive spontaneously after successful ICSI. Even when assuming that none of the families that were lost to follow-up had conceived spontaneously, one out of eight couples would have conceived spontaneously. Therefore, it is important to counsel patients about the possibility of natural conception and necessity to use contraception despite their history of subfertility.  相似文献   
94.
This paper deals with the question of whether measuring hormones is necessary in eumenorrhoeic infertility patients. The answer presented here is yes, but there are some remaining and debatable problems. In our opinion, eumenorrhoea results from regular folliculogenesis, ovulation and luteal function. To be time- and cost-effective, only a limited number of hormones should be measured and assessment of the luteal phase in an eumenorrhoeic patient by measuring oestradiol and progesterone is questionable. The paper discusses the questions on the basis of the currently available literature.  相似文献   
95.
OBJECTIVE: To describe mortality and morbidity of neonates born at <26 weeks' gestation in a contemporary population-based cohort. METHODS: We analyzed data of neonates born at <26 weeks between 1998 and 2003 in the Federal State of Hesse, Germany. Survival was calculated at 28 days and at discharge from hospital. RESULTS: Out of a total of 800 births, 572 infants were liveborn. Among those admitted for neonatal intensive care, 62.3% survived until day 28. Among the neonates followed until death or discharge, 59.6% were discharged home. Logistic regression analyses showed the following variables to be associated with an increased risk of death: Twins (Odds Ratio (OR) 3.7; 95% Confidence Interval (CI) 1.34-10.26), multiple birth >or=3 (OR 8.14; CI 1.23-53.86), intraventricular hemorrhage (IVH) >or=grade III (OR 4.79; CI 1.89-12.14), clinical risk index for babies score >15 (OR 2.9; CI 1.09-7.76), and a gestational age or=grade III and/or periventricular leukomalacia in 15%, and severe retinopathy of prematurity in 29.8%. CONCLUSIONS: This study provides outcome data derived from a contemporary population-based cohort. Mortality and complication rates remain high.  相似文献   
96.
Androgens and insulin are endocrine key players in the pathophysiology of polycystic ovary syndrome (PCOS), a heterogenic condition of unexplained etiology and a suspected genetic background. Androgens mediate the clinical phenotype of the disease. Therefore,all criteria of the recent PCOS consensus definition are based on their biological effects. Insulin resistance, followed by compensatory hyperinsulinemia, is frequently found in patients with PCOS. Insulin resistance is correlated with a risk of metabolic complications of PCOS, and recent research has focused on possible long-term health consequences of the syndrome. Newest molecular genetic findings at the receptor level of both androgens and insulin support their pivotal role in PCOS. These results could help to better characterize the heterogenic disorder, enabling a refinement of existing individualized therapeutic strategies.  相似文献   
97.
98.
99.
100.
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