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   5296篇
  免费   601篇
  国内免费   316篇
  6213篇
  2024年   21篇
  2023年   146篇
  2022年   220篇
  2021年   292篇
  2020年   262篇
  2019年   289篇
  2018年   234篇
  2017年   186篇
  2016年   201篇
  2015年   249篇
  2014年   376篇
  2013年   478篇
  2012年   295篇
  2011年   325篇
  2010年   232篇
  2009年   223篇
  2008年   254篇
  2007年   313篇
  2006年   236篇
  2005年   223篇
  2004年   184篇
  2003年   157篇
  2002年   112篇
  2001年   69篇
  2000年   77篇
  1999年   85篇
  1998年   68篇
  1997年   37篇
  1996年   53篇
  1995年   26篇
  1994年   31篇
  1993年   39篇
  1992年   32篇
  1991年   22篇
  1990年   21篇
  1989年   22篇
  1988年   14篇
  1987年   18篇
  1986年   14篇
  1985年   19篇
  1984年   16篇
  1983年   8篇
  1982年   6篇
  1981年   3篇
  1980年   7篇
  1979年   7篇
  1978年   3篇
  1977年   3篇
  1975年   3篇
  1969年   1篇
排序方式: 共有6213条查询结果,搜索用时 15 毫秒
21.
艾滋病合并隐球菌感染17例尸检材料的临床病理学研究   总被引:4,自引:0,他引:4  
在151例艾滋病尸检材料中发现17例合并隐球菌感染,均经病理学确诊,患者男15名,女2名,平均43.6岁。12例发生脑膜炎、肺炎和淋巴结炎各7例,尚见脾(6例)、肾(5例)等器官受累。9例为播散性感染。病变为慢性肉牙肿性,其中见有隐球菌。本文描述隐球菌性脑膜炎、肺炎等临床病理学表现,并讨论其病变特征与病理诊断问题。  相似文献   
22.
The data widely purporting to show the existence and heterosexual transmission in Africa of a new syndrome caused by a retrovirus which induces immune deficiency are critically evaluated. It is concluded that both acquired immune deficiency (AID) and the symptoms and diseases which constitute the clinical syndrome (S) are of long standing in Africa, affect both sexes equally and are caused directly and indirectly by factors other than human immunodeficiency virus (HIV). Seropositivity to HIV in Africans usually represents no more than cross-reactivity caused by an abundance of antibodies induced by the numerous infectious and parasitic diseases which are endemic in Africa. The apparently high prevalence of AIDS and HIV seropositives is therefore not surprising and is not proof of heterosexual transmission of either HIV or AIDS.E. Papadopulos-Eleopulos is with the Department of Medical Physics, The Royal Perth Hospital, Perth 6000, Western Australia, Australia; V.F. Turner is with the Department of Emergency Medicine, The Royal Perth Hospital, Perth 6000, Western Australia, Australia, J.M. Papadimitriou is with the Department of Pathology, University of Western Australia, Perth, Western Australia. H. Bialy is with Bio/Technology, 65 Becker St, New York, NY 10012, USA.  相似文献   
23.
24.
以感染肾综合征出血热病毒(HFRSV)的Vero E6细胞为材料,用免疫亲和层析结合制备聚丙烯酰胺凝胶电泳(PAGE)从感染细胞中提纯了HFRSV两种糖蛋白。先用免疫亲和层析从感染细胞的粗制抗原中获得含有四种蛋白的混合液,用[~3H]-氨基葡萄糖在感染细胞中标记病毒糖蛋白,观察到[~3H]-氨基葡萄糖只结合入78K和57K的病毒蛋白。再用制备SDS-PAGE从HFRSV混合液中提纯78K和57K两种蛋白。实验证明这两种糖蛋白均具中和抗原决定簇,57K的糖蛋白尚具血凝活性,初步鉴定表明这两种糖蛋白相当于文献报道的HFRSV G_1和G_2。  相似文献   
25.
Postmortem levels of native neopterin (D-erythro-neopterin) were measured in cerebral cortical samples from 44 human immunodeficiency virus type 1-infected and eight uninfected, nonneurological control patients. Cerebral cortical gray and white matter neopterin levels for the controls ranged from 0.5 to 7.2 pmol/mg of protein in contrast to neopterin levels in brains of the virus-infected patients, which frequently were more than threefold and occasionally more than 30-fold higher than mean control levels. Cortical neopterin levels did not correlate with severity of the acquired immunodeficiency syndrome dementia complex, but subcortical levels correlated with the presence of active human immunodeficiency virus type 1 infection, as reflected by pathological evidence of multinucleated giant cell encephalitis. Evidence of opportunistic cytomegalovirus infections in approximately 25% of the human immunodeficiency virus type 1-infected patients was associated with enhanced levels of neopterin in frontal cortex.  相似文献   
26.
DNA fork displacement rates were measured in three lines of Bloom's syndrome cells and in a normal diploid fibroblast line. Fork displacement rates in Bloom's cells were approx. 55–65% of the rate in normal fibroblasts.  相似文献   
27.
Background: Ehlers-Danlos syndrome (EDS) is a common non-inflammatory, congenital connective tissue disorder. Classical type (cEDS) EDS is one of the more common forms, typically caused by mutations in the COL5A1 and COL5A2 genes, though causative mutations in the COL1A1 gene have also been described. Material and methods: The study group included 59 patients of Polish origin, diagnosed with cEDS. The analysis was performed on genomic DNA (gDNA) with NGS technology, using an Illumina sequencer. Thirty-five genes related to connective tissue were investigated. The pathogenicity of the detected variants was assessed by VarSome. Results: The NGS of 35 genes revealed variants within the COL5A1, COL5A2, COL1A1, and COL1A2 genes for 30 of the 59 patients investigated. Our panel detected no sequence variations for the remaining 29 patients. Discussion: Next-generation sequencing, with an appropriate multigene panel, showed great potential to assist in the diagnosis of EDS and other connective tissue disorders. Our data also show that not all causative genes giving rise to cEDS have been elucidated yet.  相似文献   
28.
大型多钩槽绦虫与隐藏新棘虫种间关系研究   总被引:4,自引:0,他引:4  
方建平 《生态学报》2000,20(4):615-619
大型多钩槽绦虫和隐藏新棘虫单独在黄鲜肠道内分布时,其分布益十分相似,相似性系数r=0.9226(P〈0.01),当两种寄生蠕虫在黄鳝中共同感染时,随着大型多钩槽绦虫的生长,其分布位置明显前移而隐藏新棘虫的分布位置则显著后退,生态2位重叠明显下降。两种寄生蠕虫种间正关联显著,它们在宿主人共存并不改变它们的感染速度。  相似文献   
29.
The pandemic of COVID-19 is the biggest public health crisis in 21st Century. Besides the acute symptoms after infection, patients and society are also being challenged by the long-term health complications associated with COVID-19, commonly known as long COVID. While health professionals work hard to find proper treatments, large amount of knowledge has been accumulated in recent years. In order to deal with long COVID efficiently, it is important for people to keep up with current progresses and take proactive actions on long COVID. For this purpose, this review will first introduce the general background of long COVID, and then discuss its risk factors, diagnostic indicators and management strategies. This review will serve as a useful resource for people to understand and prepare for long COVID that will be with us in the foreseeable future.  相似文献   
30.
Idiopathic multicentric Castleman disease (iMCD) is a rare and life‐threatening haematologic disorder involving polyclonal lymphoproliferation and organ dysfunction due to excessive cytokine production, including interleukin‐6 (IL‐6). Clinical trial and real‐world data demonstrate that IL‐6 inhibition is effective in 34–50% of patients. mTOR, which functions through mTORC1 and mTORC2, is a recently discovered therapeutic target. The mTOR inhibitor sirolimus, which preferentially inhibits mTORC1, has led to sustained remission in a small cohort of anti‐IL‐6‐refractory iMCD patients with thrombocytopenia, anasarca, fever, renal dysfunction and organomegaly (iMCD‐TAFRO). However, sirolimus has not shown uniform effect, potentially due to its limited mTORC2 inhibition. To investigate mTORC2 activation in iMCD, we quantified the mTORC2 effector protein pNDRG1 by immunohistochemistry of lymph node tissue from six iMCD‐TAFRO and eight iMCD patients who do not meet TAFRO criteria (iMCD‐not‐otherwise‐specified; iMCD‐NOS). mTORC2 activation was increased in all regions of iMCD‐TAFRO lymph nodes and the interfollicular space of iMCD‐NOS compared with control tissue. Immunohistochemistry also revealed increased pNDRG1 expression in iMCD‐TAFRO germinal centres compared with autoimmune lymphoproliferative syndrome (ALPS), an mTOR‐driven, sirolimus‐responsive lymphoproliferative disorder, and comparable staining between iMCD‐NOS and ALPS. These results suggest increased mTORC2 activity in iMCD and that dual mTORC1/mTORC2 inhibitors may be a rational therapeutic approach.  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