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   46586篇
  免费   3694篇
  国内免费   1926篇
耳鼻咽喉   168篇
儿科学   827篇
妇产科学   490篇
基础医学   6721篇
口腔科学   509篇
临床医学   3666篇
内科学   13196篇
皮肤病学   640篇
神经病学   3102篇
特种医学   907篇
外国民族医学   2篇
外科学   3674篇
综合类   5197篇
现状与发展   5篇
预防医学   2700篇
眼科学   864篇
药学   6082篇
  6篇
中国医学   1513篇
肿瘤学   1937篇
  2023年   440篇
  2022年   597篇
  2021年   1074篇
  2020年   1148篇
  2019年   1821篇
  2018年   1792篇
  2017年   1613篇
  2016年   1586篇
  2015年   1749篇
  2014年   2859篇
  2013年   3308篇
  2012年   2614篇
  2011年   2901篇
  2010年   2178篇
  2009年   2114篇
  2008年   2096篇
  2007年   2305篇
  2006年   2028篇
  2005年   1781篇
  2004年   1564篇
  2003年   1444篇
  2002年   1218篇
  2001年   1091篇
  2000年   927篇
  1999年   822篇
  1998年   659篇
  1997年   701篇
  1996年   520篇
  1995年   576篇
  1994年   502篇
  1993年   380篇
  1992年   335篇
  1991年   261篇
  1990年   201篇
  1989年   179篇
  1988年   150篇
  1987年   131篇
  1985年   466篇
  1984年   565篇
  1983年   453篇
  1982年   418篇
  1981年   406篇
  1980年   363篇
  1979年   324篇
  1978年   276篇
  1977年   208篇
  1976年   247篇
  1975年   250篇
  1974年   196篇
  1973年   174篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
73.
目的 探讨蛋白激酶CβⅡ(PKCβⅡ)在肝细胞癌(HCC)发展中的作用机制。方法 免疫印迹法观察PKCβⅡ在肝细胞系L02和肝癌细胞系SK-hep1、HepG2、BEL-7404、7721、Hep3B和huh7中的表达,构建稳定高表达PKCβⅡ的细胞系,倒置相差显微镜下观察细胞形态变化,免疫荧光观察E-钙黏蛋白(E-cadherin)、N-钙黏蛋白(N-cadherin)表达的变化;通过免疫印迹法、实时定量聚合酶链反应(Real-time PCR)和放线菌酮(CHX)追踪实验,观察PKCβⅡ调控E-cadherin、N-cadherin和Snail表达的分子机制;小室迁移和侵袭实验(transwell assay)以及裸鼠尾静脉注射观察PKCβⅡ对肝癌细胞转移的影响;成管实验观察PKCβⅡ对人脐静脉内皮细胞(HUVECs)血管形成能力的影响,酶联免疫吸附法(ELISA)观察PKCβⅡ对肝癌细胞上清中血管内皮生长因子A(VEGFA)含量的影响。结果 PKCβⅡ在肝癌细胞系中的表达高于肝细胞系L02,PKCβⅡ促进肝癌细胞形态从鹅卵石样上皮细胞向梭行间质样细胞的转变,通过mRNA水平下调E-cadherin(P<0.05)和上调N-cadherin(P<0.01)的蛋白表达,通过翻译水平上调Snail蛋白表达,PKCβⅡ还促进了肝癌细胞的迁移、侵袭(P<0.01)以及VEGFA的分泌(P<0.01)和血管新生(P<0.01)。结论 蛋白激酶CβⅡ诱导上皮-间质转化及血管新生在肝癌的发展中有重要作用。  相似文献   
74.
ObjectiveConestat alpha, a C1-inhibitor produced by recombinant technology (rhC1-INH) is an acute treatment for edematous attacks occurring in hereditary angioedema (HAE) with C1-inhibitor deficiency (C1-INH-HAE). Our study evaluated the efficacy and safety of rhC1-INH administered during HAE attacks, and for short-term prophylaxis (STP).Materials & methodOur prospective study analyzed the course of 544 HAE attacks experienced by the 21 C1-INH-HAE patients treated, as well as the outcome of 97 instances of STP implemented with rhC1-INH. Using a purpose-designed questionnaire, the patients recorded relevant, treatment-related information.ResultsTime to the administration of rhC1-INH was 90.0 min (median) after the onset of HAE attacks. The symptoms started to improve as early as 60 min after the injection of rhC1-INH, and the attack resolved 730.0 min after treatment. The interval between the onset of the HAE attack and the administration of rhC1-INH correlated with time until the onset of improvement (R = 0.2053 p < 0.0001), and with time to the complete resolution of symptoms (R = 0.2805, p < 0.0001). Nine patients received STP with rhC1-INH in 97 instances. STP successfully prevented the HAE attack within 72 h of the event on 93/97 occasions. No local and serious systemic adverse events/effects were observed.ConclusionsTreatment with rhC1-INH is effective and safe both for acute management, and for STP. Following the onset of an HAE attack, early administration of rhC1-INH may reduce time to the improvement and to the complete resolution of symptoms. Repeated administration of rhC1-INH does not impair its efficacy.  相似文献   
75.
目的:建立鼠巨细胞病毒(MCMV)感染C57BL/6小鼠急性肝炎模型并对其感染特点进行分析及鉴定。方法:将24 只C57BL/6小鼠随机分为阴性对照组(n =12)及病毒感染组(n =12),病毒感染组腹腔注射1.0×106 PFU(200 μL)MCMV悬液,阴性对照组注射等体积小鼠胚胎成纤维细胞(MEF)悬液。于感染后第3天和第7天取外周血分离血清检测谷丙转氨酶(ALT)及谷草转氨酶(AST)。同时进行肝组织病毒分离、组织病理学及MCMV IE和M55基因、细胞因子白细胞介素-6(IL-6)、白细胞介素-1β(IL-1β)、肿瘤坏死因子α(TNF-α)的检测。结果:病毒感染组肝组织匀浆病毒分离均为阳性,肝炎发生率为100%。在感染后第3天即发生肝炎病理改变,病毒感染组血清ALT及AST较阴性对照组明显升高(P <0.01);病毒感染组肝脏HE染色第3天可见局灶性炎性细胞浸润及肝脏点灶状坏死,持续至第7天,Ishak评分较阴性对照组明显升高(P <0.01);在感染后第3天病毒感染组肝组织内可检测到MCMV IE及M55基因,且在感染后第7天仍可测得IE基因;感染后第3天及第7天病毒感染组炎性细胞因子IL-6、TNF-α及IL-1β mRNA表达水平明显升高(P <0.05)。 结论:成功建立MCMV感染C57BL/6小鼠急性动物肝炎模型,其感染表现主要集中在急性感染前期。  相似文献   
76.
77.
78.
We performed a caffeine (N-3-methyl-13C) breath test (CafeBT) to determine whether it can be employed to identify caffeine metabolism-associated single nucleotide polymorphisms. The study included 130 healthy adults (mean age: 21.9 years). Saliva was collected using an Oragene®•DNA saliva collection kit. Breath samples were collected from the subjects. The subjects orally ingested 100 mg 13C-caffeine dissolved in distilled water. Subsequently, breath samples were collected in bags every 10 min for a total of 90 min. An analysis of 13CO2 in the expired breath was performed by infrared spectroscopy, and the sum of Δ13CO2 over 90 min (S90m) was calculated. DNA from saliva samples was genotyped using TaqMan® SNP Genotyping for the following genes: cytochrome P4501A2: rs762551, rs2472297, aryl-hydrocarbon receptor (rs4410790), and adenosine A2A receptor (rs5751876). All subjects had the genotype CC in rs2472297 alleles. No significant difference was observed in S90m among the genotypes of rs762551 and rs5751876; however, a significant difference was found in S90m among the genotypes of rs4410790 (C > T). Our findings suggest that the N-3 demethylation of caffeine is dependent on the rs4410790 allele and that CafeBT may be used to determine rs4410790 genotypes.  相似文献   
79.
The advent of direct-acting antivirals (DAAs) has provided the impetus to transplant kidneys from hepatitis C virus-positive donors into uninfected recipients (D+/R−). Thirty D+/R− patients received DAA treatment. Sustained virologic response (SVR12) was defined as an undetectable viral load in 12 weeks after treatment. An age-matched cohort of uninfected donor and recipient pairs (D−/R−) transplanted during same time period was used for comparison. The median day of viral detection was postoperative day (POD) 2. The detection of viremia in D+/R− patients was 100%. The initial median viral load was 531 copies/μL (range: 10-1 × 108 copies/μL) with a median peak viral load of 3.4 × 105 copies/μL (range: 804-1.0 × 108 copies/μL). DAAs were initiated on median POD 9 (range: 5-41 days). All 30 patients had confirmed SVR12. During a median follow-up of 10 months, patient and graft survival was 100%, and acute rejection was 6.6% with no major adverse events related to DAA treatment. Delayed graft function was significantly decreased in D+/R− patients as compared to the age-matched cohort (27% vs 60%; P = .01). D+/R− transplantation offers patients an alternative strategy to increase access.  相似文献   
80.
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