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   3797篇
  免费   237篇
  国内免费   163篇
耳鼻咽喉   10篇
儿科学   37篇
妇产科学   71篇
基础医学   793篇
口腔科学   37篇
临床医学   210篇
内科学   683篇
皮肤病学   43篇
神经病学   481篇
特种医学   70篇
外国民族医学   2篇
外科学   185篇
综合类   526篇
现状与发展   1篇
预防医学   84篇
眼科学   21篇
药学   435篇
中国医学   61篇
肿瘤学   447篇
  2024年   4篇
  2023年   13篇
  2022年   38篇
  2021年   56篇
  2020年   53篇
  2019年   53篇
  2018年   57篇
  2017年   72篇
  2016年   78篇
  2015年   116篇
  2014年   153篇
  2013年   193篇
  2012年   155篇
  2011年   214篇
  2010年   193篇
  2009年   228篇
  2008年   241篇
  2007年   242篇
  2006年   246篇
  2005年   205篇
  2004年   188篇
  2003年   183篇
  2002年   133篇
  2001年   93篇
  2000年   96篇
  1999年   70篇
  1998年   63篇
  1997年   79篇
  1996年   61篇
  1995年   53篇
  1994年   47篇
  1993年   40篇
  1992年   41篇
  1991年   33篇
  1990年   42篇
  1989年   31篇
  1988年   28篇
  1987年   30篇
  1986年   19篇
  1985年   31篇
  1984年   40篇
  1983年   23篇
  1982年   38篇
  1981年   32篇
  1980年   24篇
  1979年   24篇
  1978年   15篇
  1977年   13篇
  1976年   8篇
  1973年   4篇
排序方式: 共有4197条查询结果,搜索用时 265 毫秒
91.
We compared the Sanger sequencing and the commercial INNO-LiPA® HBV assay for the routine detection of precore (PC) and basal core promoter (BCP) mutations of hepatitis B virus in chronically infected patients. The overall agreement rate between assays was 94.2% and 98.8% for the detection of PC and BCP mutations, respectively.  相似文献   
92.
93.
94.
95.
Epigenetic mechanisms participate in melanoma development and progression. The effect of histone modifications and their catalysing enzymes over euchromatic promoter DNA methylation in melanoma remains unclear. This study investigated the potential association of p16INK4A promoter methylation with histone methyltransferase SETDB1 expression in Greek patients with sporadic melanoma and their correlation with clinicopathological characteristics. Promoter methylation was detected by methylation‐specific PCR in 100 peripheral blood samples and 58 melanoma tissues from the same patients. Cell proliferation (Ki‐67 index), p16INK4A and SETDB1 expression were evaluated by immunohistochemistry. High‐frequency promoter methylation (25.86%) was observed in tissue samples and correlated with increased cell proliferation (= 0.0514). p16INK4A promoter methylation was higher in vertical growth‐phase (60%) melanomas than in radial (40%, = 0.063) and those displaying epidermal involvement (= 0.046). Importantly, p16INK4A methylation correlated with increased melanoma thickness according to Breslow index (= 0.0495) and marginally with increased Clark level (I/II vs III/IV/V, = 0.070). Low (1–30%) p16INK4A expression was detected at the majority (19 of 54) of melanoma cases (35.19%), being marginally correlated with tumor lymphocytic infiltration (= 0.078). SETDB1 nuclear immunoreactivity was observed in 47 of 57 (82.46%) cases, whereas 27 of 57 (47.37%) showed cytoplasmic immunoexpression. Cytoplasmic SETDB1 expression correlated with higher frequency of p16INK4A methylation and p16INK4A expression (= 0.033, = 0.011, respectively). Increased nuclear SETDB1 levels were associated with higher mitotic count (0–5/mm2 vs >5/mm2, = 0.0869), advanced Clark level (III‐V, = 0.0380), epidermal involvement (= 0.0331) and the non‐chronic sun exposure‐associated melanoma type (= 0.0664). Our data demonstrate for the first time the association of histone methyltransferase SETDB1 with frequent methylation of the euchromatic p16INK4A promoter and several prognostic parameters in melanomas.  相似文献   
96.
97.
《Annales d'endocrinologie》2016,77(2):114-125
Mammalian parental care is essentially provided by the mother and it occupies most of the reproductive period for female. The synchronization of maternal behavior with parturition and lactation ensures that the mother responds to the needs of the young at the appropriate time. This temporal synchrony is accomplished by hormonal changes that underly both the onset of maternal behavior and of parturition and lactation. The aim of this review is to describe and compare the hormonal mechanisms that regulate the onset of maternal behavior across a variety of mammals, including humans, that represent different behavioral strategies. Are involved the steroid hormones, estradiol and progesterone synthesized by the ovaries which primed the future mother to repond maternally. In response to these steroids, oxytocin release induced by vaginocervical stimulation and prolactin release affect the maternal brain. The medial preoptic area integrates the hormonal signals to regulate maternal behavior. The hormonal cocktail that stimulates maternal behavior varies across mammalian species. Because most of the studies in humans are correlative and because human environment is complex, direct causality between hormones and maternal behavior is unclear. However, one can reasonably think that hormones create a positive bias towards the baby increasing the occurrence of maternal behavior.  相似文献   
98.
Adenoviral cancer gene therapy approaches have resulted in promising recent results. Following only a decade of intense development, some of the crucial obstacles are now being overcome. Insufficient transduction has been the main limitation of earlier approaches. A new approach for increasing transduction of tumour cells is utilisation of replication-competent oncolytic agents, such as conditionally replicating adenoviruses (CRADs). The anti-tumour effect is caused by replication of the virus per se and, thus, replication must be restricted to tumour cells to protect normal tissues from damage. Tissue-specific promoters (TSPs) represent a powerful tool for decreasing the toxicity of cancer gene therapy to normal tissues and have previously been utilised for specific mutation compensation or delivery of prodrug-converting enzymes. However, TSPs can also be used for controlling crucial viral replication regulators and consequent restriction of replication to tumour cells. Initial clinical trials have demonstrated the safety and suggested efficacy for TSP-controlled CRADs as a novel approach for cancer gene therapy.  相似文献   
99.
《Autoimmunity》2013,46(3):163-170
In addition to its well known effects on reproductive organs and lactation the pituitary hormone prolactin (PRL) also influences immune functions. The present investigation was performed in order to clarify the regulatory role of prolactin in autoimmune disease by using the collagen II arthritis model. Groups of virgin female DBA/1 mice were subjected to different short-term treatment protocols (5-10 days) with rat PRL and the drugs bromocriptine (inhibits prolactine secretion) and haloperidol (enhances prolactin secretion). Treatments were performed at different stages of disease development, and effects on clinical scores, anti-collagen II antibody titres as well as agalactosyl IgG levels were recorded. The effects of the treatment protocols on serum PRL levels were assessed by using a radioimmunoassay (RIA) system. Although the accumulated results of the present study indicate that PRL does not fulfil a major role in the regulation of collagen II arthritis, some interesting observations were made. High levels of PRL (PRL injections) made the arthritis worse only if treatment was performed during the induction stage of the disease. Bromocriptine treatment during the immunisation period did not significantly affect the course of arthritis, but treatment at later stages tended to cause exacerbation (significant at the onset period only). These results indicate that PRL has different effects during early and late stages of the development of collagen 11-induced arthritis.  相似文献   
100.
Maternal care involves the consistent and coordinated expression of a variety of behaviours over an extended period of time, and adverse changes in maternal care can have profound impacts on the CNS and behaviour of offspring. This complex behavioural pattern depends on a number of integrated neuroendocrine mechanisms. This review will discuss the use of animal models in the study of the role of maternal care in shaping CNS function, the contributions of corticosteroid releasing hormone, vasopressin, oxytocin, and prolactin in this process, the molecular mechanisms involved, and the translational relevance of this research.  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