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   43851篇
  免费   3288篇
  国内免费   1308篇
耳鼻咽喉   115篇
儿科学   637篇
妇产科学   383篇
基础医学   5665篇
口腔科学   879篇
临床医学   3227篇
内科学   4871篇
皮肤病学   318篇
神经病学   4056篇
特种医学   1261篇
外国民族医学   3篇
外科学   1858篇
综合类   4009篇
现状与发展   2篇
一般理论   1篇
预防医学   4282篇
眼科学   258篇
药学   10880篇
  12篇
中国医学   3807篇
肿瘤学   1923篇
  2023年   617篇
  2022年   815篇
  2021年   1434篇
  2020年   1412篇
  2019年   1404篇
  2018年   1370篇
  2017年   1508篇
  2016年   1444篇
  2015年   1389篇
  2014年   2315篇
  2013年   3773篇
  2012年   2096篇
  2011年   2498篇
  2010年   1745篇
  2009年   2018篇
  2008年   1974篇
  2007年   1965篇
  2006年   1685篇
  2005年   1498篇
  2004年   1302篇
  2003年   1173篇
  2002年   1040篇
  2001年   975篇
  2000年   727篇
  1999年   708篇
  1998年   622篇
  1997年   563篇
  1996年   537篇
  1995年   662篇
  1994年   519篇
  1993年   487篇
  1992年   488篇
  1991年   446篇
  1990年   422篇
  1989年   420篇
  1988年   369篇
  1987年   366篇
  1986年   336篇
  1985年   460篇
  1984年   417篇
  1983年   291篇
  1982年   370篇
  1981年   285篇
  1980年   297篇
  1979年   216篇
  1978年   224篇
  1977年   168篇
  1976年   197篇
  1975年   84篇
  1974年   75篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Cataloguing the effects of different types of stress on behaviour and physiology in rodent models has not been comprehensively attempted. Here, we systematically review whether chronic exposure to physical stress, psychosocial stress, or both types of stress can induce different behavioural and neurobiological outcomes in male and female rodents. We found that physical stress consistently increased depressive-like behaviour, impaired social interaction and decreased body weight, while psychosocial stress consistently increased both anxiety- and depressive-like behaviour, impaired social interaction and learning and memory, increased HPA axis activity, peripheral inflammation and microglial activation, and decreased hippocampal neurogenesis in male rodents. Moreover, we found that the combined effect of both stress types resulted in a more severe pathological state defined by increased anxiety- and depressive-like behaviour, impaired social interaction and learning and memory, increased HPA axis activity and central inflammation, and reduced hippocampal neurogenesis and neural plasticity in male rodents. Phenotypes for females were less consistent, irrespective of the type of stress exposure, on account of the limited number of studies using females. This review highlights that the type of stress may indeed matter and will help animal researchers to more appropriately choose a stress/depression model that fits their research purposes.  相似文献   
92.
Activity spaces are increasingly used to understand how people interact with their environment and engage in activity but their use may raise challenges regarding causal inference. We conducted a systematic review of findings and the methodological, analytical and conceptual issues relevant to causal inference. Studies were included if they comprised a spatial summary of locations visited, assessed any part of the causal pathway between the environment, physical activity and health, and used quantitative or qualitative methods. We searched seven electronic databases in January 2018 and screened 11910 articles for eligibility. Forty-seven studies were included for review. Studies answered research questions about features of or environmental features within activity spaces using a range of spatial and temporal summary techniques. The conceptual challenge of using activity spaces to strengthen causal inference was rarely considered, although some studies discussed circularity, temporality, and plausibility. Future studies should use longitudinal and experimental designs and consider the potential and actual use of spaces for physical activity, and their relationship with total levels of activity.  相似文献   
93.
荜拔酰胺为叔胺型酰胺类生物碱,该成分主要存在于胡椒科植物长柄胡椒以及瘤突变胡椒等的根中。荜拔酰胺具有抗血小板聚集、抗炎和抗肿瘤等多种药理活性,其衍生物也具有多种多样的活性。笔者综述了荜拔酰胺的结构修饰及其生物活性的研究进展,为荜拔酰胺类化合物的进一步研究提供参考。  相似文献   
94.
95.
Gastrodia elata Bl. is a traditional Chinese herbal medicine with special pharmacological effects on headache and numbness. However, its wild sources are now in short supply because of over-excavation. A total of 14 endophytic fungi were isolated from Gastrodia elata Bl collected from Yinjing, in which 10 strains were identified, including Neonectria, Ascomycota, Fusarium, Oidiodendron and Dothiorella. All crude extracts showed some degrees of antioxidant activities by T-AOC method and DPPH methods, especially those from Oidiodendron GeR6 and Ascomycota sp. GeR2, which might be attributed due to their high phenolic contents. However, only Oidiodendron GeR6 contained gastrodin (39.2 μg/g) as the host plant in the crude extracts. In conclusion, the notable activities of GeR6 indicated its medical use as a natural antioxidant agent, as well as substitutable use for Gastrodia elata Bl. in the future.  相似文献   
96.
97.
目的:探讨醛-酮还原酶家族7成员A3(AKR7A3)在肺腺癌中的异常表达及与临床病理特征的关系,并探究其临床意义。方法:采用生物信息学数据库分析、免疫组化、Western Blot、Real-time PCR等方法对肺腺癌组织及不同细胞中AKR7A3的表达进行检测与分析。结果:Oncomine数据库分析结果显示,在肺腺癌中,AKR7A3的表达普遍高于正常肺组织,分别为正常肺组织的1.811倍(P=0.022)、1.356倍(P<0.01)、1.413倍(P=0.002)。Kaplan-Meier Plotter数据库分析结果显示,AKR7A3高表达的患者较低表达的患者生存时间缩短,差异具有统计学意义(P=0.003 7)。免疫组化染色显示肺腺癌组织中AKR7A3的表达较癌旁增高,在与临床病理特征的相关性分析中,发现其与肿瘤分化程度(P<0.01)、淋巴结转移情况(P=0.029)以及TNM分期(P<0.01)相关,且会造成患者生存时间缩短(P=0.031)。Cox多因素分析表明AKR7A3可能是影响肺腺癌患者预后的独立危险因素(P=0.012)。Western Blot及Real-time PCR实验提示不同肺腺癌细胞中AKR7A3蛋白及mRNA表达普遍增高。结论:AKR7A3在肺腺癌中表达增高,对预后有不良影响,有促进肿瘤发生发展的作用。  相似文献   
98.
中药质量的评控问题是制约中药现代化发展的瓶颈,因此有必要在现有检测方法的基础上结合生物评价,继而更为全面地保证中药质量。生物评价是完善中药质量标准、保证临床功效和安全性评价的重要方法,已成为中药质量标准化发展趋势之一。在此处主要论述了近年来基于生物活性与效应基准的中药质量评价技术和已取得的部分研究进展,同时对目前中药质量生物评价研究与应用中存在的主要问题进行探讨,进一步对其未来应用做出展望,从而更好的对中药质量进行控制。  相似文献   
99.
Abstract

This study tested whether the effect of self-referencing in a health-marketing message was amplified or attenuated when combined with message framing and narrative. Hispanic adults (N?=?146) were randomly assigned to read and respond to an obesity prevention message. Self-referencing messages generated greater cognitive elaboration but only when placed in a narrative. Conversely, self-referencing messages highlighting health risks of obesity produced higher levels of involvement and intention to increase physical activity and healthy eating. Health marketing professionals can use these findings to enhance the effectiveness of obesity prevention messages that target Hispanic adults.  相似文献   
100.
Infections caused by Gram-positive and -negative bacteria are one of the foremost causes of morbidity and mortality globally. Antibiotics are the mainstay of therapy for bacterial infections, but the emergence and wide spread of drug-resistant pathogens have already become a huge issue for public healthcare systems. The coumarin moiety, which is ubiquitous in nature, could bind to the B subunit of DNA gyrase in bacteria and inhibit DNA supercoiling by blocking the ATPase activity; hence, coumarin derivatives possess potential antibacterial activity. Several coumarin-containing hybrids such as coumermycin A1, clorobiocin, and novobiocin have already been used in clinical practice for the treatment of various bacterial infections; thus, it is conceivable that hybridization of the coumarin moiety with other antibacterial pharmacophores may provide opportunities for the development of novel antibiotics. This review outlines the advances in coumarin-containing hybrids with antibacterial potential in the recent 5 years and the structure–activity relationships are also discussed.  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