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   2886篇
  免费   172篇
  国内免费   10篇
耳鼻咽喉   25篇
儿科学   96篇
妇产科学   55篇
基础医学   467篇
口腔科学   71篇
临床医学   208篇
内科学   658篇
皮肤病学   86篇
神经病学   223篇
特种医学   108篇
外科学   264篇
综合类   9篇
预防医学   164篇
眼科学   97篇
药学   219篇
中国医学   12篇
肿瘤学   306篇
  2023年   18篇
  2022年   34篇
  2021年   92篇
  2020年   52篇
  2019年   48篇
  2018年   74篇
  2017年   47篇
  2016年   65篇
  2015年   69篇
  2014年   112篇
  2013年   108篇
  2012年   180篇
  2011年   217篇
  2010年   127篇
  2009年   88篇
  2008年   206篇
  2007年   205篇
  2006年   212篇
  2005年   209篇
  2004年   209篇
  2003年   168篇
  2002年   159篇
  2001年   26篇
  2000年   19篇
  1999年   36篇
  1998年   34篇
  1997年   24篇
  1996年   23篇
  1995年   26篇
  1994年   16篇
  1993年   18篇
  1992年   9篇
  1991年   16篇
  1990年   7篇
  1989年   10篇
  1988年   10篇
  1987年   5篇
  1985年   5篇
  1984年   7篇
  1983年   4篇
  1982年   6篇
  1980年   7篇
  1978年   6篇
  1977年   8篇
  1976年   4篇
  1973年   5篇
  1972年   5篇
  1971年   3篇
  1969年   3篇
  1968年   3篇
排序方式: 共有3068条查询结果,搜索用时 15 毫秒
1.
BACKGROUND: Psychotic symptoms in Alzheimer disease (AD+P) identify a heritable phenotype associated with more rapid cognitive decline. The authors have proposed that AD+P is itself a composite of a misidentification and a paranoid subtype with increased cognitive impairment restricted to the misidentification type. Most prior studies of the clinical correlates of AD+P have been limited, however, by the inclusion of prevalent cases. METHODS: Subjects with possible or probable AD or mild cognitive impairment (MCI) without psychosis at study entry were assessed at the time of initial presentation and then annually. Psychotic symptoms were assessed using the CERAD Behavioral Rating Scale. Survival analyses used Cox proportional hazard models with time-dependent covariates to examine the predictors of psychosis onset. RESULTS: A total of 288 subjects completed at least one follow-up examination. Mean duration of follow-up was 22.1 months. The incidence of psychosis was 0.19 per person-year. Cognitive impairment was associated with onset of psychosis, largely as a result of its association with onset of the misidentification, but not the paranoid, subtype. Including psychotropic medication use in the model revealed an association of antidepressant use with the onset of psychosis. This latter association appeared to arise from an underlying association between depression and the risk of psychosis onset rather than from antidepressant treatment. CONCLUSION: These findings are consistent with the hypothesis that the misidentification and the paranoid subtypes each define a more biologically homogeneous group than AD+P as a whole. Further exploration of the relationship between depressive symptoms and psychosis in patients with AD is warranted.  相似文献   
2.
BACKGROUND: Decreased plasma adiponectin is associated with impaired endothelial function and, thereby, increased risk for cardiovascular events. Glucocorticoid (GC) affects vascular endothelial cells either favourably or harmfully depending upon the dosages and duration. We examined the effect of GC pulse therapy on vascular endothelial function. METHODS: Fourteen young patients with IgA nephropathy were evaluated for flow-mediated vasodilation (FMD), plasma levels of adiponectin both in high molecular weight (HMW adiponectin) form and in single molecular form (total adiponectin), hepatocyte growth factor (HGF), asymmetric dimethylarginine (ADMA), and high-sensitive C-reactive protein, before and after a course of GC pulse therapy. RESULTS: GC pulse therapy significantly decreased FMD (from 7.2 +/- 2.6 to 5.7 +/- 2.5%, P < 0.01). Meanwhile, plasma adiponectin levels were significantly augmented (total adiponectin: from 10.2 +/- 4.0 to 12.1 +/- 6.3 microg/ml, P < 0.05; HMW: from 6.5 +/- 3.2 to 7.7 +/- 3.3 microg/ml, P < 0.05). In parallel, elevated concentrations of serum HGF (from 0.28 +/- 0.12 to 0.63 +/- 0.38 ng/ml, P < 0.01) and plasma ADMA (from 0.45 +/- 0.07 to 0.53 +/- 0.04 nmol/ml, P < 0.05) were observed. CONCLUSIONS: GC pulse therapy impaired endothelial function while increasing plasma adiponectin levels, which may in turn restore the endothelial function in patients with IgA nephropathy.  相似文献   
3.
Although there are effective antibacterial agents against plague, newer antibacterial agents have been developed which show more potent activity against other bacterial organisms, but have not been tested againstYersinia pestis. A strain ofYersinia pestis was selected (no. 22; National Institute of Infectious Diseases, Tokyo, Japan) that caused a systemic infection in mice.Y. pestis no. 22 was intraperitoneally inoculated into DDY-strain mice, and 13 oral or 6 injectable antibacterial drugs given to the infected mice at varying doses 1 and 24 hours after infection. Levofloxacin, sparfloxacin and ofloxacin were the most effective oral agents against the infection, and prulifloxacin and pazufloxacin were also effective but to a lesser extent. Also, gentamicin and arbekacin were the most potent injectable antibacterial agents againstY. pestis. These results suggest that there are several new drugs, both oral and injectable, which exert excellent in vivo antibacterial activity against a mouse infection model and may be useful for the clinical treatment of plague.  相似文献   
4.
5.
6.
OBJECTIVE: To evaluate a proposed technique for the 3-dimensional (3D) detection of hemangiomas, including vascular malformation and their feeding arteries, in the head and neck. The new technique combines phase-contrast magnetic resonance angiography (PCMRA) without contrast medium and 3D fast asymmetric spin-echo (FASE) sequences. METHODS: The technique was applied to 3 patients having hemangiomas in the head and neck region. In 1 patient the image obtained with the proposed technique was compared to that obtained by standard contrast angiography. RESULTS: In all 3 patients, the 3D presence of the hemangiomas and the feeding arteries were well defined in images created by the proposed technique. Additionally, the characterization of the hemangioma's 3D structure and distribution of the feeding arteries coincided with those observed using contrast angiography in the case for which contrast angiography was also performed. CONCLUSIONS: Preliminary experience shows that the proposed technique combining 3D-FASE and 3D-PCMRA is useful to visualize both the 3D structure of hemangiomas and to identify the 3D distribution of the feeding arteries without using contrast medium.  相似文献   
7.
8.
9.
iNKT cells are a unique subset of CD1-restricted T lymphocytes that express T cell receptor (TCR) and some NK receptors. iNKT cells express an invariant TCRalpha chain composed of Valpha14-Jalpha18 segments in mice and Valpha24-Jalpha18 segments in humans associated with TCRbeta chains using a restricted set of Vbeta. iNKT cells recognize glycolipid antigens such as alpha-galactosylceramide (alpha-GC) presented by CD1d, non-pormorphic MHC class I-like molecule, and rapidly secrete large amounts of cytokines including IL-4 and IFN-gamma upon activation. Due to its potent ability to produce a variety of cytokines, iNKT cells are involved in a various kinds of immunoregulation. iNKT cells play a regulatory role in some disease models such as type I diabetes in NOD mice. In contrast, iNKT cells exaggerate the pathogenesis such as arthritis, allergic airway inflammation and atherosclerosis. In addition, iNKT cells are an attractive target for immunotherapy because several different synthetic glycolipid antigens to modify the function of iNKT cells are available. In this review, we examine the potential roles of NKT cells in the pathogenesis of a variety of diseases including autoimmunity , allergy, infection and cancer. Additionally, we discuss on the recent advances in glycolipid therapy for these disease models.  相似文献   
10.
Alopecia areata universalis developed gradually over nine months in a 25-year-old woman. When her scalp hairs were totally lost and other body hair began to fall out, the symptoms of insulin dependent diabetes mellitus, an organ-specific autoimmune disease, developed rapidly and progressed to diabetic coma. Alopecia did not regress after the metabolic state improved following insulin therapy. Biopsy of the scalp skin revealed significant reduction of the total number of hair bulbs and prominent lymphocyte infiltration into the remaining hair follicles. Insulin dependent diabetes mellitus and alopecia areata universalis are both thought to be related to the autoimmune mechanism and sometimes coexist. However, simultaneous development of these two disorders is extremely rare.  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