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   3385387篇
  免费   252196篇
  国内免费   5017篇
耳鼻咽喉   47168篇
儿科学   111105篇
妇产科学   93841篇
基础医学   491742篇
口腔科学   96810篇
临床医学   305985篇
内科学   649257篇
皮肤病学   74112篇
神经病学   270165篇
特种医学   129222篇
外国民族医学   902篇
外科学   508965篇
综合类   76491篇
现状与发展   13篇
一般理论   1299篇
预防医学   267304篇
眼科学   79317篇
药学   253684篇
  13篇
中国医学   6360篇
肿瘤学   178845篇
  2018年   35781篇
  2017年   27253篇
  2016年   30537篇
  2015年   34730篇
  2014年   48802篇
  2013年   73916篇
  2012年   101099篇
  2011年   107367篇
  2010年   63786篇
  2009年   60494篇
  2008年   101350篇
  2007年   107762篇
  2006年   108955篇
  2005年   106005篇
  2004年   102529篇
  2003年   98206篇
  2002年   95841篇
  2001年   151205篇
  2000年   155958篇
  1999年   131879篇
  1998年   38346篇
  1997年   33980篇
  1996年   33969篇
  1995年   32494篇
  1994年   30204篇
  1993年   28516篇
  1992年   105531篇
  1991年   103177篇
  1990年   100782篇
  1989年   97399篇
  1988年   90176篇
  1987年   88532篇
  1986年   83711篇
  1985年   80636篇
  1984年   60453篇
  1983年   51850篇
  1982年   30780篇
  1981年   27751篇
  1979年   56808篇
  1978年   40231篇
  1977年   33745篇
  1976年   32147篇
  1975年   34382篇
  1974年   41607篇
  1973年   39790篇
  1972年   37140篇
  1971年   35075篇
  1970年   32346篇
  1969年   30735篇
  1968年   28099篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
Recent seroepidemiologic and pathologic evidence suggests that prior infection with Epstein-Barr virus (EBV) may be necessary for the development of multiple sclerosis (MS). EBV infects more than 90% of all humans, most of whom remain healthy. In contrast, 99% of MS patients have evidence of prior infection with EBV. EBV infects resting B lymphocytes, immortalizing them into long-lived memory B cells that survive largely undetected by the immune system in the peripheral circulation. MS patients show elevated titers to EBV years before developing any neurologic symptoms. Postmortem pathologic analysis of brains of patients with MS has revealed diffuse EBV-associated B-cell dysregulation in all forms of MS. Theories of pathogenesis of EBV in MS include antigenic mimicry, immortalization of B-cell clones, and cytotoxic T-cell dysfunction against virally infected B cells. This article reviews the existing evidence of the relationship between EBV and MS and considers the therapeutic implication of this evidence.  相似文献   
994.
995.
R-mode factor analysis was applied to characterize the chemical composition of human teeth investigated by particle induced X-ray emission (PIXE), Rutherford backscattering spectrometry (RBS) and X-ray fluorescence (XRF) techniques. The approach developed in this study enabled the separation between essential mineral teeth components and the pollutants deposited in teeth tissues during the human life. The three independent sources of metals incorporated in human teeth were found. The first source, representing about 43% of the variance of the concentration data, was characterized by pollutant elements of power industry emissions. The second factor was loaded with toxic elements of general urban pollution. The third factor represented the tooth source as it contained mainly large fractions of the mineral components of the tooth tissue as Ca and K.  相似文献   
996.
997.
998.
999.
Background:  Clusterin is a ubiquitous 80 kDa heterodimeric glycoprotein previously shown to be expressed on tumor cells of systemic and, to a lesser extent, primary cutaneous anaplastic large cell lymphoma (PC-ALCL). Lymphomatoid papulosis (LyP), an important differential diagnosis of ALCL, has been studied for clusterin expression in only a small number of cases. The aim of this study was to compare clusterin immunostaining patterns in LyP and other cutaneous histologic simulants with those of PC-ALCL.
Methods:  Formalin-fixed, paraffin-embedded sections of PC-ALCL (6), LyP (20), mycosis fungoides with large cell transformation (MF-LCT, 12), pityriasis lichenoides et varioliformis acuta (PLEVA, 12), arthropod bite reaction (ABR, 12) and lymphomatoid reactions (LR, 9) were immunostained for clusterin and evaluated for staining pattern and distribution. All diagnoses were made with clinicopathologic correlation.
Results:  Characteristic dot-like Golgi staining was identified in 10/20 LyP (50%), 4/6 PC-ALCL (67%) and 9/12 MF-LCT (75%). Two of 12 PLEVA (17%), 1 of 12 ABR (8%) and 2 of 8 LR (25%) had lymphocytes (< 25%) with diffuse cytoplasmic staining. Dermal dendritic cells stained strongly for clusterin. High background staining occurred in some cases.
Conclusion:  Clusterin immunostaining does not reliably distinguish between LyP, PC-ALCL or MF-LCT, but could distinguish LyP from its reactive histologic simulants.  相似文献   
1000.
Glomeruloid haemangioma is considered a specific marker of POEMS ( p olyneuropathy, o rganomegaly, e ndocrinopathy, M -protein and s kin changes) syndrome and it is usually but not always associated with multicentric Castleman's disease. We report a 78-year-old man who presented with a single, red-violet soft nodule with superficial telangiectases on the scalp. Histopathologically, the lesion consisted of lobules of coiled aggregated capillaries that involved the lumina of dilated vascular structures, mimicking renal glomeruli. A collagenous stroma separated the capillary lobules, and eosinophilic, periodic-acid–Schiff positive globules of varying sizes and shapes were seen within the cytoplasm of endothelial cells. Immunohistochemical studies with antibodies against IgA and IgG, and against the kappa and lambda light chains of immunoglobulins showed immunoreactivity within the eosinophilic globules. Results of complete blood count, liver, renal and thyroid function tests, fasting blood sugar measurement, serum levels of oestradiol, testosterone, prolactin and cortisol, serum protein electrophoresis, immunoelectrophoresis and immunofixation yielded normal or negative results. No Bence–Jones proteinuria was found in a sample from a 24-h urine collection. To our knowledge, only two cases of glomeruloid haemangioma have been previously reported in patients without POEMS syndrome. We describe the third case of glomeruloid haemangioma in a patient without features of POEMS syndrome.  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