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   2509篇
  免费   250篇
  国内免费   150篇
儿科学   202篇
妇产科学   108篇
基础医学   187篇
口腔科学   2篇
临床医学   251篇
内科学   679篇
皮肤病学   9篇
神经病学   6篇
特种医学   50篇
外科学   356篇
综合类   434篇
预防医学   183篇
眼科学   3篇
药学   226篇
  1篇
中国医学   94篇
肿瘤学   118篇
  2024年   11篇
  2023年   45篇
  2022年   85篇
  2021年   123篇
  2020年   111篇
  2019年   74篇
  2018年   82篇
  2017年   99篇
  2016年   114篇
  2015年   104篇
  2014年   158篇
  2013年   164篇
  2012年   140篇
  2011年   152篇
  2010年   144篇
  2009年   119篇
  2008年   135篇
  2007年   107篇
  2006年   126篇
  2005年   101篇
  2004年   101篇
  2003年   81篇
  2002年   71篇
  2001年   71篇
  2000年   50篇
  1999年   34篇
  1998年   30篇
  1997年   39篇
  1996年   27篇
  1995年   18篇
  1994年   19篇
  1993年   21篇
  1992年   12篇
  1991年   14篇
  1990年   20篇
  1989年   14篇
  1988年   20篇
  1987年   4篇
  1986年   12篇
  1985年   4篇
  1984年   9篇
  1982年   11篇
  1981年   4篇
  1980年   6篇
  1979年   4篇
  1977年   2篇
  1976年   4篇
  1974年   2篇
  1973年   4篇
  1971年   3篇
排序方式: 共有2909条查询结果,搜索用时 15 毫秒
71.
ObjectivePreterm infants receive long-term parenteral nutrition (PN) for gastrointestinal immaturity. This study aimed to determine if mixed lipid emulsions containing fish oil decrease the incidence of PN-associated cholestasis by reducing oxidative stress and providing an anti-inflammatory effect.MethodsThis retrospective cohort study enrolled 399 very low birth weight premature infants (gestational age ≤32 weeks) between January 2009 and November 2017 at a single neonatal intensive care unit. Preterm infants received total PN with either mixed lipid emulsion including fish oil (SMOFlipid®, n = 195) or soybean oil-based lipid emulsion (Lipovenoes®, n = 204) for at least 7 days. We compared the outcomes of PN-associated cholestasis, comorbidities, and mortality between the groups.ResultsThe incidence of PN-associated cholestasis was significantly lower in the SMOFlipid group than in the Lipovenoes group. The duration to full feeding days was significantly shorter in the SMOFlipid group compared with the Lipovenoes group. Relevant complications, such as severe retinopathy of prematurity and bronchopulmonary dysplasia, were also significantly reduced in the SMOFlipid group compared with the Lipovenoes group.ConclusionIn premature infants, PN with fish oil-based lipid emulsions is associated with a lower incidence of PN-associated cholestasis compared with soybean oil-based lipid emulsions.  相似文献   
72.
Recently the authors have reported the potent beneficial effect of caffeic acid phenethyl ester (CAPE) on cholestatic oxidative liver injury induced by acute bile ligation in Swiss albino rats. Herein, they report the ultrastructural hepatocellular alterations induced by acute bile duct ligation and the effect of CAPE administration on these alterations. Bile duct ligation resulted in many degenerative changes, such as vacuolization, mitochondrial degeneration, endoplasmic reticulum dilatation, and lysosome accumulation within the cytoplasm of hepatocytes. Mitochondrial degeneration was also observed within the cytoplasm of the cells of biliary ductular epithelium. CAPE potentially protected the hepatocytes from the cholestasis-induced cellular injury.  相似文献   
73.
Hepatitis C Virus (HCV) is a major etiological agent of chronic hepatitis, cirrhosis and hepatocellular carcinoma. Fas-mediated apoptosis is the major cause of hepatocyte damage during liver disease. The present work was performed to study the fas system (Fas-FasL and soluble Fas) in chronic hepatitis C infection. Also, to correlate the degree of liver cell damage with the Fas system. The study was carried out on 45 patients positive for HCV RNA by nested RT-PCR in addition to 13 HCV negative control subjects. Wedge liver biopsies samples were obtained from patients and controls during abdominal operations for determination of cellular expression of Fas and Fas-L on hepatocytes and infiltrating lymphocytes respectively by flow cytometry. Histological activity index (HAI) was determined in chronic HCV patients. Also blood samples were taken from patients and controls for determination of sFas. There was statistically insignificant difference in Fas expression in hepatocytes of patients (P?=?0.34) in comparison to control. Meanwhile, there was a statistically significant decrease in FasL expression in patients compared to control (P< 0.001) and statistically significant increase in soluble Fas in patients compared to control (P < 0.001). The HAI of liver fibrosis for all patients were within mild score with mean ± SD 4 ± 0.5. From this study, we could conclude that Fas system is one of the important pathways regulating the response to HCV infection. Increased serum sFas in HCV patients is accompanied by down-regulation of Fas/Fas-L expression resulting in inhibition of apoptosis in liver cells as a process for elimination of virus infected cells and this may ultimately leads to chronicity of the disease.  相似文献   
74.
目的:探讨基质金属蛋白酶2(MMP-2)与基质金属蛋白酶9(MMP-9)在肝内胆管细胞癌(ICC)组织中的表达及其与ICC患者临床病理特征及预后的关系。方法:收集2011年1月—2014年12月收治的50例ICC患者的癌组织与癌旁组织手术标本,采用免疫组织化学方法及RT-PCR方法检测MMP-2和MMP-9在以上组织中的表达,分析MMP-2和MMP-9表达与ICC患者临床病理参数以及术后生存率的关系。结果:免疫组织化学结果显示,ICC组织中MMP-2和MMP-9蛋白阳性表达率分别为34.0%和32.0%,而两者在癌旁组织中无阳性表达;RT-PCR结果显示,ICC组织中MMP-2和MMP-9的相对表达均明显高于癌旁组织(均P0.05)。MMP-2和MMP-9表达与ICC患者是否存在淋巴结转移和肿瘤分化程度有关(均P0.05),而与患者性别、年龄和肿瘤分期无关(均P0.05);MMP-2和MMP-9阳性患者生存率明显低于各自阴性者,而两者均阳性患者的生存率最低(均P0.05)。结论:ICC组织中MMP-2和MMP-9表达明显上调,且两者的表达与ICC患者恶性临床病理特征及不良预后密切相关。  相似文献   
75.
76.
目的 明确肝外胆管结石及胆囊结石并发肝内胆管癌(Intrahepatic cholangiocarcinoma,ICC)风险,为胆道结石的临床治疗提供参考.方法 计算机检索PubMed、EmBase以及CBM等数据库,查找胆道结石以及胆囊结石并发ICC风险的队列研究或者病例对照研究.应用STATA软件对所获得研究数据行Meta分析,根据研究间异质性选择固定效应模型或者随机效应模型.采用Egger检验评估发表偏倚.结果 共有6篇病例对照研究纳入分析,包括123 713例患者,其中ICC 4 753例,无瘤对照118 960例.Meta分析结果显示,胆管结石为ICC发病的高危因素(OR:17.64,95% CI:11.14 ~27.95),除外肝内胆管结石,肝外胆管结石导致的ICC发病风险仍较高(OR:11.79,95% CI:4.17~ 33.35).此外,胆囊结石也是ICC发病危险因素(OR:2.07,95% CI:1.17 ~3.67).结论 肝外胆管结石与胆囊结石均为ICC发病的重要危险因素.  相似文献   
77.
AIM:To investigate the contribution of ABCB4 mutations to pediatric idiopathic gallstone disease and the potential of hormonal contraceptives to prompt clinical manifestations of multidrug resistance protein 3 deficiency.METHODS:Mutational analysis of ABCB4,screening for copy number variations by multiplex ligation-dependent probe amplification,genotyping for low expression allele c.1331T>C of ABCB11 and genotyping for variation c.55G>C in ABCG8 previously associated with cholesterol gallstones in adults was performed in 35 pediatric subjects with idiopathic gallstones who fulfilled the clinical criteria for low phospholipid-associated cholelithiasis syndrome(LPAC,OMIM#600803)and in 5young females with suspected LPAC and their families(5 probands,15 additional family members).The probands came to medical attention for contraceptiveassociated intrahepatic cholestasis.RESULTS:A possibly pathogenic variant of ABCB4was found only in one of the 35 pediatric subjects with idiopathic cholesterol gallstones whereas 15 members of the studied 5 LPAC kindreds were confirmed and another one was highly suspected to carry predictably pathogenic mutations in ABCB4.Among these 16,however,none developed gallstones in childhood.In 5index patients,all young females carrying at least one pathogenic mutation in one allele of ABCB4,manifestation of LPAC as intrahepatic cholestasis with elevated serum activity of gamma-glutamyltransferase was induced by hormonal contraceptives.Variants ABCB11c.1331T>C and ABCG8 c.55G>C were not significantly overrepresented in the 35 examined patients with suspect LPAC.CONCLUSION:Clinical criteria for LPAC syndrome caused by mutations in ABCB4 cannot be applied topediatric patients with idiopathic gallstones.Sexual immaturity even prevents manifestation of LPAC.  相似文献   
78.
79.
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