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   11951篇
  免费   141篇
  国内免费   8篇
教育   8181篇
科学研究   1239篇
各国文化   346篇
体育   1089篇
综合类   4篇
文化理论   120篇
信息传播   1121篇
  2022年   100篇
  2021年   150篇
  2020年   230篇
  2019年   338篇
  2018年   428篇
  2017年   453篇
  2016年   375篇
  2015年   245篇
  2014年   277篇
  2013年   2182篇
  2012年   302篇
  2011年   264篇
  2010年   236篇
  2009年   238篇
  2008年   286篇
  2007年   261篇
  2006年   232篇
  2005年   204篇
  2004年   208篇
  2003年   162篇
  2002年   139篇
  2001年   174篇
  2000年   198篇
  1999年   178篇
  1998年   108篇
  1997年   97篇
  1996年   99篇
  1995年   85篇
  1994年   87篇
  1993年   96篇
  1992年   145篇
  1991年   159篇
  1990年   160篇
  1989年   171篇
  1988年   138篇
  1987年   128篇
  1986年   121篇
  1985年   160篇
  1984年   134篇
  1983年   124篇
  1982年   108篇
  1981年   85篇
  1980年   93篇
  1979年   148篇
  1978年   94篇
  1977年   94篇
  1976年   85篇
  1975年   84篇
  1974年   94篇
  1973年   83篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
952.
953.
954.
Hemodialysis represents a chronic stress status for its recipients. Many hypotheses state that this may be associated with oxidative stress. Thus, there may be deficiency of antioxidants like erythrocytic superoxide dismutase, catalase, vitamin E or increased generation of free radicals like superoxide anions. A study was carried out to investigate oxidant and antioxidant status in chronic renal failure patients undergoing hemodialysis and effect of vitamin E supplementation on these two status. Blood samples were collected from patients before and after hemodialysis and from controls. The samples were analyzed for quantitation of MDA as index of lipid peroxide, nitric oxide, vitamin E, vitamin C and enzymatic antioxidants namely erythrocyte SOD and catalase. As compared to controls, the levels of serum MDA were significantly increased and activities of erythrocyte SOD and catalase, levels of serum nitric oxide, serum vitamin E and plasma vitamin C were significantly decreased both before and after hemodialysis. The efficiency of vitamin E therapy in hemodialysis patients was assessed by re-evaluating oxidant and antioxidant status of same patients after supplementation of vitamin E. Vitamin E supplementation caused decrease in serum MDA and increase in levels of serum nitric oxide, vitamin E, vitamin C and activities of erythrocytic SOD and catalase. Our results suggest the presence of oxidative stress and the possible preventive role of vitamin E therapy in hemodialysis patients.  相似文献   
955.
Due to its importance in fitness centers, a number of authors have explored and analyzed loyalty. However, two characteristics not yet examined are service convenience in fitness center chains and low-cost fitness centers (an emerging business model). In the present study, the authors sought to understand the relationship among perceived quality and service convenience on perceived value, satisfaction, and client loyalty in low-cost fitness centers. Clients (N = 763; 381 women and 382 men) from three low-cost Spanish fitness centers were surveyed, revealing a positive relationship among the variables studied. Findings demonstrate the importance of proper management of non-monetary sacrifices and perceived quality by the managers of these sport organizations, since client loyalty could depend on factors of these emerging sport models.  相似文献   
956.
Premature coronary artery disease (CAD) is common in India. We, therefore, studied oxidative stress, dyslipidemia, and high sensitivity-C reactive protein (hs-CRP) levels in young CAD patients. Present study consisted of male CAD patients below 40 years and age and sex matched healthy controls (n=30 each). Fasting blood samples were analyzed for serum lipid profile, malondialdehyde, antioxidant enzymes and hs-CRP levels. Dyslipidemia was observed in 90% of the young CAD patients, of which 72.2% showed increased serum triglycerides and decreased HDL-cholesterol. LDL-cholesterol levels were high in 77.8%. Serum malondialdehyde and hs-CRP levels were increased significantly (p<0.0001) as compared to controls. hs-CRP levels were in high risk range in all the young patients. However, glutathione peroxidase activity was reduced significantly (p<0.05). Our data suggests that elevated hs-CRP levels along with dyslipidemia and oxidative stress adds to the predictive value of premature CAD in young Indians.  相似文献   
957.
The preliminary building program suggested in this paper makes use of outlines, graphs, charts, and lists, rather than long-winded paragraphs, to describe the needs, objectives, and philosophy of the library. It is hoped that a short, concise, but detailed, report using these methods will save time and make the report more attractive to read, thereby encouraging the many people who will need to assist in the building planning to use the report.  相似文献   
958.
The present research developed a measure for exposure to both antisocial and prosocial media content by revising and extending a previous Content-based Media Exposure Scale (C-ME). The validity and reliability of the C-ME2 was tested in two independent samples (= 678), among young adults (Study 1) and adolescents (Study 2). Results of Confirmatory Factor Analyses showed good fit, in both studies, for both antisocial and prosocial dimensions of media content, and for both males and females. Furthermore, the C-ME2 explains unique variance beyond previous measures of violent and general media exposure. Evidence is presented of reliability, discriminant and predictive validity of the C-ME2, measuring both frequency and exposure to specific content of media. The C-ME2 covers all media platforms, is easy to use in all research designs, and allows for standardization and systematic comparisons across studies.  相似文献   
959.
960.
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