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   2459175篇
  免费   176439篇
  国内免费   3422篇
耳鼻咽喉   33868篇
儿科学   79701篇
妇产科学   65239篇
基础医学   364412篇
口腔科学   67232篇
临床医学   220572篇
内科学   476565篇
皮肤病学   54897篇
神经病学   196627篇
特种医学   92610篇
外国民族医学   489篇
外科学   369865篇
综合类   47995篇
现状与发展   12篇
一般理论   883篇
预防医学   188908篇
眼科学   56829篇
药学   182821篇
  11篇
中国医学   4742篇
肿瘤学   134758篇
  2021年   20009篇
  2019年   20683篇
  2018年   29452篇
  2017年   22417篇
  2016年   25389篇
  2015年   27849篇
  2014年   38518篇
  2013年   58411篇
  2012年   80435篇
  2011年   85872篇
  2010年   50729篇
  2009年   46970篇
  2008年   81157篇
  2007年   86351篇
  2006年   86876篇
  2005年   84331篇
  2004年   80560篇
  2003年   77904篇
  2002年   75439篇
  2001年   112007篇
  2000年   115498篇
  1999年   95869篇
  1998年   28065篇
  1997年   24539篇
  1996年   24746篇
  1995年   23281篇
  1994年   21470篇
  1993年   20266篇
  1992年   72525篇
  1991年   70532篇
  1990年   68834篇
  1989年   66115篇
  1988年   60710篇
  1987年   59585篇
  1986年   55605篇
  1985年   53572篇
  1984年   39865篇
  1983年   33851篇
  1982年   20375篇
  1979年   36270篇
  1978年   26017篇
  1977年   21621篇
  1976年   20674篇
  1975年   22170篇
  1974年   26481篇
  1973年   25096篇
  1972年   23429篇
  1971年   22293篇
  1970年   20492篇
  1969年   19516篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
24.
25.
Objective: Polyunsaturated fatty acids n-3 (PUFA n-3) have shown effects in reducing tumor growth, in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) abundantly present in fish oil (FO). When these fatty acids are provided in the diet, they alter the functions of the cells, particularly in tumor and immune cells. However, the effects of α-linolenic fatty acid (ALA), which is the precursor of EPA and DHA, are controversial. Thus, our objective was to test the effect of this parental fatty acid. Methods: Non-tumor-bearing and tumor-bearing Wistar rats (70 days) were supplemented with 1 g/kg body weight of FO or Oro Inca® (OI) oil (rich in ALA). Immune cells function, proliferation, cytokine production, and subpopulation profile were evaluated. Results: We have shown that innate immune cells enhanced phagocytosis capacity, and increased processing and elimination of antigens. Moreover, there was a decrease in production of pro-inflammatory cytokines (tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6)) by macrophages. Lymphocytes showed decreased proliferation capacity, increased cluster of differentiation 8 (CD8+) subpopulation, and increased TNF-α production. Conclusions: Oil rich in ALA caused similar immune modulation in cancer when compared with FO.  相似文献   
26.
Individuals with sudden unilateral deafness offer a unique opportunity to study plasticity of the binaural auditory system in adult humans. Stimulation of the intact ear results in increased activity in the auditory cortex. However, there are no reports of changes at sub-cortical levels in humans. Therefore, the aim of the present study was to investigate changes in sub-cortical activity immediately before and after the onset of surgically induced unilateral deafness in adult humans. Click-evoked auditory brainstem responses (ABRs) to stimulation of the healthy ear were recorded from ten adults during the course of translabyrinthine surgery for the removal of a unilateral acoustic neuroma. This surgical technique always results in abrupt deafferentation of the affected ear. The results revealed a rapid (within minutes) reduction in latency of wave V (mean pre = 6.55 ms; mean post = 6.15 ms; p < 0.001). A latency reduction was also observed for wave III (mean pre = 4.40 ms; mean post = 4.13 ms; p < 0.001). These reductions in response latency are consistent with functional changes including disinhibition or/and more rapid intra-cellular signalling affecting binaurally sensitive neurons in the central auditory system. The results are highly relevant for improved understanding of putative physiological mechanisms underlying perceptual disorders such as tinnitus and hyperacusis.  相似文献   
27.
28.
29.
30.
Abstract

Objective: To understand the origin of extremely high gonadotropin levels in a perimenopausal woman.

Methods: A 52-year-old woman with a 2?months of amenorrhea followed spontaneous menstrual cycles recovery was referred to our outpatient clinic with elevated follicle-stimulating hormone (FSH, 483 mUI/ml), luteinizing hormone (LH, 475 mUI/ml) and prolactin (PRL, 173?ng/ml). She was known to take levosulpiride. The gonadotropin levels did not fit with the clinical features.

Results: A gonadotroph tumor was ruled out. Further analysis confirmed constantly high FSH, LH and PRL levels. The measurements were repeated using different analytical platforms with different results. After serial dilutions, nonlinearity was present suggesting an immunoassay interference. After post-polyethylene glycol recovery, hormone levels appeared in the normal range. Anti-goat antibodies were recognized in the serum of the patient.

Conclusions: This case report shows a case of falsely abnormal high gonadotropin and PRL levels in a woman during menopause transition. In the clinical practice the evaluation of gonadotropin profile is not recommended at this age, but the abnormal levels stimulated further evaluation. An interference in the assay due to anti-goat antibodies resulted in abnormally high level of FSH and LH. A strict collaboration between clinicians and the laboratory is needed, when laboratory findings do not correspond to clinical findings.  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