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   4609篇
  免费   394篇
  国内免费   203篇
耳鼻咽喉   19篇
儿科学   36篇
妇产科学   66篇
基础医学   405篇
口腔科学   67篇
临床医学   249篇
内科学   496篇
皮肤病学   116篇
神经病学   165篇
特种医学   54篇
外科学   220篇
综合类   365篇
预防医学   652篇
眼科学   65篇
药学   1336篇
中国医学   812篇
肿瘤学   83篇
  2024年   33篇
  2023年   77篇
  2022年   175篇
  2021年   220篇
  2020年   170篇
  2019年   160篇
  2018年   133篇
  2017年   233篇
  2016年   239篇
  2015年   243篇
  2014年   306篇
  2013年   662篇
  2012年   292篇
  2011年   280篇
  2010年   215篇
  2009年   195篇
  2008年   205篇
  2007年   199篇
  2006年   185篇
  2005年   159篇
  2004年   144篇
  2003年   137篇
  2002年   110篇
  2001年   90篇
  2000年   45篇
  1999年   50篇
  1998年   52篇
  1997年   35篇
  1996年   32篇
  1995年   18篇
  1994年   17篇
  1993年   12篇
  1992年   13篇
  1991年   7篇
  1990年   6篇
  1989年   13篇
  1988年   4篇
  1987年   8篇
  1986年   6篇
  1985年   5篇
  1984年   6篇
  1983年   1篇
  1982年   5篇
  1981年   2篇
  1980年   2篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
排序方式: 共有5206条查询结果,搜索用时 0 毫秒
31.
ContextSchisandra chinensis (Turcz.) Baill. (Magnoliaceae) essential oil (SCEO) composition is rich in lignans that are believed to perform protective effects in the liver.ObjectiveThis study investigates the effects of SCEO in the treatment of acetaminophen (APAP)-induced liver injury in mice.Materials and methodsC57BL/6 mice (n = 56) were randomly divided into seven groups: normal; APAP (300 mg/kg); APAP plus bicyclol (200 mg/kg); APAP plus SCEO (0.25, 0.5, 1, 2 g/kg). Serum biochemical parameters for liver function, inflammatory factors, and antioxidant activities were determined. The protein expression levels of Nrf2, GCLC, GCLM, HO-1, p62, and LC3 were assessed by western blotting. Nrf2, GCLC, HO-1, p62, and LC3 mRNA were detected by real-time PCR.ResultsCompared to APAP overdose, SCEO (2 g/kg) pre-treatment reduced the serum levels of AST (79.4%), ALT (84.6%), TNF-α (57.3%), and IL-6 (53.0%). In addition, SCEO (2 g/kg) markedly suppressed cytochrome P450 2E1 (CYP2E1) (15.4%) and attenuated the exhaustion of GSH (43.6%) and SOD (16.8%), and the accumulation of MDA (22.6%) in the liver, to inhibit the occurrence of oxidative stress. Moreover, hepatic tissues from our experiment revealed that SCEO pre-treatment mitigated liver injury caused by oxidative stress by increasing Nrf2, HO-1, and GCL. Additionally, SCEO activated autophagy, which upregulated hepatic LC3-II and decreased p62 in APAP overdose mice (p < 0.05).Discussion and conclusionsOur evidence demonstrated that SCEO protects hepatocytes from APAP-induced liver injury in vivo and the findings will provide a reliable theoretical basis for developing novel therapeutics.  相似文献   
32.
ContextDeer antler based active ingredients are known to have certain anti-inflammatory and antioxidant activities. However, its potential hepatoprotective effect remains unclear.ObjectiveThis article reports the hepatoprotective effect of protein components in deer antler bases (R1) on lipopolysaccharide/d-galactosamine (LPS/d-GalN)-induced acute liver injury (ALI) in mice, and explores its possible mechanism.Materials and methodsThe four separated and purified protein components of deer antler bases were screened and verified by the RAW264.7 cell inflammation model. In the in vivo experiment of LPS/d-GalN-induced ALI in mice, ALT, AST, SOD, CAT, GSH and MDA were detected. The liver histopathology was analysed, the COX-2 and iNOS proteins were analysed by immunohistochemistry, and 4-HNE was analysed by immunofluorescence staining. In addition, the effects on the MAPK pathway and NF-κB/IκB-α pathway in liver proteins were explored.ResultsWith isolated RA protein fraction pre-treated RAW264.7 cells, NO production decreased by 35.3% compared with the model group. The experimental results of ALI in mice induced by LPS/d-GalN show that R1 protein components can protect mice from ALI through anti-inflammatory and anti-oxidative stress effects and reduce liver pathological damage in mice. The results also indicate that the R1 protein component may protect the liver by inhibiting the activation of the MAPK pathway and the NF-κB/IκB-α pathway induced by LPS/d-GalN.ConclusionsThe separated and purified R1 protein component of deer antler base has a good protective effect on LPS/d-GalN-induced liver injury, and may become a potential material for protecting against liver injury.  相似文献   
33.
槲寄生抗氧化物质的研究测定   总被引:9,自引:0,他引:9  
宰学明  吴国荣  龚祝南  陆长梅  邵志广 《中草药》2001,32(12):1081-1083
目的;研究槲寄生抗化物质并进行活性测定。方法:分别测定了槲寄生Viscum coloratum(Kom.)Nakai叶,茎,果中超氧化歧化酶(SOD),过氧化氢酶(CAT),过氧化物酶(POD),谷胱甘肽过氧化物酶(GSH-Px)等抗氧化酶的活性,GSH,绿原酸,类黄酮等小分子抗氧化物质的含量以及总抗氧化能力。结果:发现该植物富含抗氧化物质。结论:表明槲寄生所含抗化活性物质种类多,数量大,具很强的抗氧化能力,尤以叶为最。  相似文献   
34.
为研究蒙药组方塔米尔对正常小鼠的抗疲劳作用和剧烈运动小鼠的抗氧化作用,将小鼠随机分阴性对照、那仁满都拉和塔米尔组等3组,进行负重游泳实验、缺氧试验、耐热试验以及不负重游泳10min后检测肝、肾、脑和骨胳肌组织总超氧化物歧化酶、谷胱甘肽过氧化物酶酶活力和丙二醛的含量。结果表明,蒙药组方塔米尔可显著或极显著(P〈0.05或P〈0.01)延长小鼠竭力死亡时间、缺氧存活时间和耐热存活时间;显著降低(P〈0.05)剧烈运动小鼠不同组织MDA含量,并能显著(P〈0.05)提高骨骼肌中总超氧化物歧化酶活力,极显著(P〈0.01)提高脑、肾、骨骼肌组织谷胱甘肽过氧化物酶活力。  相似文献   
35.
研究表明,茶多酚具有很强的消除有害自由基、抗衰老等多种药理作用[1],茶多酚临床治疗白癜风具有较明显的效果,但其各类组分在临床治疗白癜风所发挥的作用还未见报道。1材料与方法1.1动物C57BL/6(B6)小鼠,体质量(20±2)g,由浙江中医药大学实验动物中心提供。1.2主要药品与试剂H2O2、EGCG均购自美国Sigma公  相似文献   
36.
苏州产淡水珍珠生物活性评价及镇静活性物质基础研究   总被引:1,自引:0,他引:1  
目的对苏州产淡水珍珠的镇静、养阴、抗氧化及酪氨酸酶抑制等生物活性进行评价,并针对其镇静活性的物质基础开展研究。方法采用小鼠在黑箱中自发活动计数的方法考察其镇静作用;利用Sephadex G-100对珍珠热提液进行分离,并评价不同相对分子质量段部位的镇静活性,探讨镇静活性的物质基础。建立甲状腺素小鼠阴虚模型考察养阴作用;通过使用改进的邻苯三酚自氧化法及测定SOD、MDA含量考察抗氧化作用。结果珍珠热提液中大、小相对分子质量段部位均有显著的镇静活性;热提液能够明显增强阴虚状态下小鼠的抗疲劳、耐缺氧的能力,有效抑制阴虚状态下各脏器功能的衰减;冷浸液能显著提高小鼠血清SOD含量、降低MDA含量。结论珍珠具有良好的镇静、养阴和抗氧化作用;珍珠的镇静活性源于多组分物质共同作用的结果。  相似文献   
37.
目的 设计合成一系列3,4-二氢4-芳基香豆素类化合物,并评价其抗氧化、抗肿瘤活性.方法 以取代苯甲醛为原料,经缩合及Ponndorf反应制得目标化合物.采用DPPH法测定目标化合物的抗氧化活性;采用MTT法以胃癌细胞BGC-823为测试细胞株对目标化合物进行体外抗肿瘤活性评价.结果 与结论合成了10个新的3,4-二氢...  相似文献   
38.
Ischemic heart diseases are one of the major causes of death worldwide. Effective restoration of blood flow can significantly improve patients’ quality of life and reduce mortality. However, reperfusion injury cannot be ignored. Flavonoids possess well-established antioxidant properties;They also have other benefits that may be relevant for ameliorating myocardial ischemia-reperfusion injury(MIRI). In this review,we focus on flavonoids with cardiovascular-protection function and emphasize their pharmacological effects. The main mechanisms of flavonoid pharmacological activities against MIRI involve the following aspects: a) antioxidant, b) anti-inflammatory, c) anti-platelet aggregation, d) anti-apoptosis, and e)myocardial-function regulation activities. We also summarized the effectiveness of flavonoids for MIRI.  相似文献   
39.
Objective Edible bird’s nest (EBN) is a popular traditional tonic food in Chinese population for centuries. Malaysia is one of the main EBN suppliers in the world. This study aims to explore the best strategy to boost the antioxidant potential of EBN solution. Methods In this study, the raw EBN (4%, mass to volume ratio) was initially enzymatic hydrolyzed using papain enzyme to produce EBN hydrolysate (EBNH), then spray-dried into powdered form. Next, 4% (mass to volume ratio) of EBNH powder was dissolved in ginger extract (GE), mulberry leaf extract (MLE) and cinnamon twig extract (CTE) to detect the changes of antioxidant activities, respectively. Results Results obtained suggest that enzymatic hydrolysis significantly reduced the viscosity of 4% EBN solution from (68.12 ± 0.69) mPa.s to (7.84 ± 0.31) mPa.s. Besides, the total phenolic content (TPC), total flavonoid content (TFC), total soluble protein, DPPH scavenging activity and ferric reducing antioxidant power (FRAP) were substantially increased following EBN hydrolysis using papain enzyme. In addition, fortification with GE, MLE and CTE had further improved the TPC, TFC, DPPH scavenging activity and FRAP of the EBNH solution. Among the samples, MLE-EBNH solution showed the most superior antioxidant potential at (86.39 ± 1.66)% of DPPH scavenging activity and (19.79 ± 2.96) mmol/L FeSO4 of FRAP. Conclusion This study proved that combined enzymatic hydrolysis and MLE fortification is the best strategy to produce EBN product with prominent in vitro antioxidant potential. This preliminary study provides new insight into the compatibility of EBN with different herbal extracts for future health food production.  相似文献   
40.
The roots of Bupleurus spp. have been used in traditional Chinese herbal medicine for curing liver diseases. Although bioactive saikosaponins have been detected in the leaves as well as in the roots, the aerial parts of the plants are discarded as waste. In the present study, a leaf infusion of B. kaoi Liu, Chao et Chuang, an indigenous Bupleurus species in Taiwan, was prepared and the antioxidant properties and in vitro hepatoprotective activity were demonstrated. The results show that the leaf infusion exerted DPPH free radical scavenging activity, inhibitory capacity on superoxide anion formation and superoxide anion scavenging activity. The hepatotoxicity of acetaminophen (APAP) and carbon tetrachloride (CCl4) on the rat liver cells were also decreased by the leaf infusion.  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