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   28685篇
  免费   2770篇
  国内免费   2263篇
耳鼻咽喉   238篇
儿科学   314篇
妇产科学   317篇
基础医学   3709篇
口腔科学   479篇
临床医学   3920篇
内科学   4634篇
皮肤病学   250篇
神经病学   1458篇
特种医学   1046篇
外国民族医学   21篇
外科学   2977篇
综合类   4506篇
现状与发展   9篇
一般理论   4篇
预防医学   1749篇
眼科学   718篇
药学   2864篇
  31篇
中国医学   1531篇
肿瘤学   2943篇
  2024年   115篇
  2023年   508篇
  2022年   1316篇
  2021年   1664篇
  2020年   1241篇
  2019年   989篇
  2018年   1073篇
  2017年   919篇
  2016年   876篇
  2015年   1386篇
  2014年   1705篇
  2013年   1342篇
  2012年   2029篇
  2011年   2268篇
  2010年   1378篇
  2009年   1095篇
  2008年   1421篇
  2007年   1484篇
  2006年   1404篇
  2005年   1534篇
  2004年   906篇
  2003年   807篇
  2002年   762篇
  2001年   635篇
  2000年   634篇
  1999年   707篇
  1998年   525篇
  1997年   477篇
  1996年   402篇
  1995年   365篇
  1994年   289篇
  1993年   164篇
  1992年   233篇
  1991年   178篇
  1990年   147篇
  1989年   136篇
  1988年   153篇
  1987年   101篇
  1986年   96篇
  1985年   71篇
  1984年   41篇
  1983年   34篇
  1982年   28篇
  1981年   22篇
  1980年   10篇
  1979年   18篇
  1978年   5篇
  1975年   3篇
  1971年   5篇
  1969年   5篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Li  Yuying  Huang  Haixin  Lan  Tian  Wang  Wei  Zhang  Jie  Zheng  Min  Cao  Liang  Sun  Wenchao  Lu  Huijun 《Virus genes》2021,57(3):284-288

Lyon IARC polyomavirus (LIPyV), a newly discovered polyomavirus (PyV), was first identified in 2017 in human skin samples in the USA. Later, it was detected in several other countries in samples of human and feline origin. Our aim was to find out if the virus occurs in China. To this end, 100 fecal samples were collected from cats with diarrhea in Guangxi Province during 2016 and 2018 and tested with polymerase chain reaction (PCR). Only 2 samples that originated from two related individuals were found to be positive. Based on the sequence identity of the 240-bp PCR products, the two positive samples supposedly contained identical viruses. Therefore, only one of them, which was designated as LIPyV-GXNN01, was selected for full genome amplification, cloning, sequencing and analysis. LIPyV-GXNN01, which comprises 5,263 nucleotides, has an early region that consists of small T antigen (ST-Ag) and large T antigen (LT-Ag) and a late region coding for the VP1, VP2, and VP3 structural proteins. Moreover, the LIPyV-GXNN01 strain structural proteins share 95.9–99.4%, 97.6–99.2%, and 97.1–99.2% nucleic acid identity with the VP1, VP2, and VP3of other LIPyV reference strains, respectively. A phylogenetic analysis revealed that GXNN01 clustered together with previously reported LIPyV strain. This present study is the first report of LIPyV in China.

  相似文献   
992.
The pandemic of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused an unprecedented global social and economic impact, and high numbers of deaths. Many risk factors have been identified in the progression of COVID-19 into a severe and critical stage, including old age, male gender, underlying comorbidities such as hypertension, diabetes, obesity, chronic lung diseases, heart, liver and kidney diseases, tumors, clinically apparent immunodeficiencies, local immunodeficiencies, such as early type I interferon secretion capacity, and pregnancy. Possible complications include acute kidney injury, coagulation disorders, thoromboembolism. The development of lymphopenia and eosinopenia are laboratory indicators of COVID-19. Laboratory parameters to monitor disease progression include lactate dehydrogenase, procalcitonin, high-sensitivity C-reactive protein, proinflammatory cytokines such as interleukin (IL)-6, IL-1β, Krebs von den Lungen-6 (KL-6), and ferritin. The development of a cytokine storm and extensive chest computed tomography imaging patterns are indicators of a severe disease. In addition, socioeconomic status, diet, lifestyle, geographical differences, ethnicity, exposed viral load, day of initiation of treatment, and quality of health care have been reported to influence individual outcomes. In this review, we highlight the scientific evidence on the risk factors of severity of COVID-19.  相似文献   
993.
Despite the availability of antibiotics, current therapies to treat sepsis are still ineffective and many clinical trials aimed at neutralizing specific inflammatory cytokines have failed, suggesting the urgent need for new treatments. Using two models of LPS-induced endotoxemia and cecal ligation and puncture (CLP)–induced sepsis, we investigated the effects of C1q/TNF-related protein 4(CTRP4) on septic lethality and sepsis-induced inflammation. The effects of CTRP4 on survival, inflammation, organ damage, and bacterial clearance were assessed. Here, we found that CTRP4 decreased the mortalities of mice and alleviated pathological lung injury in mice model. In vivo depletion and adoptive transfer studies showed CTRP4-expressing macrophages as the key cell type inhibiting LPS-induced septic shock. The mechanism associated with the CTRP4 deficiency involved promoting of TLR4 internalization and activation of downstream pathways that resulted in a lethal, prolonged proinflammatory cytokine storm. Treatment of macrophages with exogenous CTRP4 abrogated proinflammatory cytokine production. Our results showed CTRP4 regulates inflammatory response and could be a promising strategy to treat septic shock.  相似文献   
994.
995.
我国北方蜱中人粒细胞埃立克体16S rRNA基因的检测   总被引:17,自引:0,他引:17  
本文应用人粒细胞埃立克体病 ( HGE)的病原体的 1 6S r RNA基因序列的特异引物对采自我国北方地区的一些蜱标本进行扩增 ,首次从内蒙古大兴安岭采集的全沟硬蜱、森林革蜱和嗜群血蜱 ,以及从新疆精河采集的全沟硬蜱和草原革蜱中扩增出该病原体的 1 6S r RNA基因片段。所测出的 967bp序列与美国 HGE株 ( Gen Bank U0 2 52 1 )的同源性为 1 0 0 %  相似文献   
996.
J. Cao  Q. Xu  A. Koda 《Inflammation research》2000,49(11):578-583
OBJECTIVE AND DESIGN: To investigate the role of nitric oxide (NO) in the liver injury induced by delayed-type hypersensitivity to picryl chloride (PCl-DTH). MATERIALS AND METHODS: Liver injury was induced in mice by PCl-DTH. NO production was examined using the Griess reagent. Isolated hepatocytes (HC) and nonparenchymal cells (NPC) were used. RESULTS: NO production in both serum and liver tissue reached a peak at 36 h after the elicitation of liver injury. The in vitro NO production was only observed by NPC or HC isolated at 24 h after the injury. Co-stimulation of IFN-gamma and TNF-alpha significantly triggered the HC and NPC isolated at 0 h to produce NO. As NO synthase inhibitors, Nomega-Nitro-L-Arginine exacerbated the liver injury in mice and NG-Monomethyl-L-Arginine enhanced the hepatotoxicity of IFN-gamma and TNF-alpha in vitro. In contrast, NO producer, S-nitroso-N-acetylpenicillamine dose-dependently inhibited the hepatotoxicity of NPC. CONCLUSIONS: NO may be produced by HC and NPC under the co-stimulation of IFN-gamma and TNF-alpha, and may play an important role for alleviating the liver injury.  相似文献   
997.
Human C-reactive protein (CRP) 1059G/C polymorphism   总被引:8,自引:0,他引:8  
We found a novel G → C change at nucleotide 1059 within exon 2 of the CRP gene encoding the C-reactive protein. The CRP 1059G/C polymorphism could be detected by digestion with endonuclease MaeIII. The frequency of the CRP 1059C allele was 0.109 in Caucasians, but it was absent from Canadian Oji-Cree. Because of the importance of the CRP gene product in inflammation and its recent association with ischemic heart disease syndromes, this polymorphism may be useful in the association studies of atherosclerosis and its related phenotypes. Received: November 8, 1999 / Accepted: November 15, 1999  相似文献   
998.
999.
目的 :探讨肺癌组织中MDR1mRNA、nm2 3H1mRNA、P gp和CD44v6的表达及其与淋巴结转移、病理分型的相关性。方法 :应用原位杂交 (ISH)CSA法和免疫组化EnVision法检测 6 0例人原发性肺癌组织MDR1nm2 3H1mRNA、P gp和CD44v6的表达。结果 :MDR1mRNA、nm2 3H1mRNA、P gp混合单抗和CD44v6的阳性率分别为 46 6 7% (2 8/ 6 0 )、5 3 33 % (32 / 6 0 )、5 1 6 7% (31/ 6 0 )和 6 3 33% (38/ 6 0 )。不同克隆P gp阳性率分别为JSB 133 33% (2 0 / 6 0 ) ,C2 1931 70 % (19/ 6 0 )和C49416 70 % (10 / 6 0 )。nm2 3H1mRNA与肺癌的第一站和第二站淋巴结转移呈负相关 (P <0 0 1,P <0 0 5 ) ,而CD44v6呈正相关(P <0 0 1,P <0 0 1)。MDR1mRNA和P gp与CD44v6的阳性表达关系密切 (P <0 0 1) ,并与肺癌患者吸烟关系密切 (P <0 0 1)。MDR1mRNA和P gp的阳性符合率为 80 6 4% (2 5 / 31)。 结论 :IHC方法检测P gp能间接反映MDR1mRNA的转录水平 ,为准确评估肺癌病人对化疗的疗效提供一种有效手段 ,MDR的表达与病人吸烟关系密切  相似文献   
1000.
Variants of the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene have been suggested to play an important role in the pathogenesis of atherosclerosis and ischemic stroke.This study was aimed to explore the association of ALOX5AP variants with ischemic stroke risk in Han Chinese of eastern China.A total of 690 ischemic stroke cases and 767 controls were recruited.The subjects were further subtyped according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria.On the basis of that,two polymorphisms of the ALOX5AP gene (rs10507391 and rs12429692) were determined by TaqMan genotyping assay.In addition,plasma leukotriene B4 (LTB4) levels were analyzed in these subjects.There was no evidence of association between the two variants of ALOX5AP and the risk of ischemic stroke or its TOAST-subtypes.Haplotype analysis and stratification analysis according to sex,age,body mass index,hypertension,and diabetes also showed negative association.Analysis of LTB4 levels in a subset of cases and controls revealed that LTB4 levels were significantly higher in ischemic stroke cases than in the controls (70.06±14.75 ng/L vs 57.34±10.93 ng/L;P=0.000) and carriers of the T allele of the rs10507391 variant were associated with higher plasma LTB4 levels (P=0.000).The present study suggests there is no association of the two polymorphisms in the ALOX5AP gene with ischemic stroke risk in Han Chinese of eastern China.  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