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   12405篇
  免费   15篇
教育   9592篇
科学研究   1237篇
各国文化   18篇
体育   374篇
文化理论   386篇
信息传播   813篇
  2024年   44篇
  2023年   4篇
  2022年   19篇
  2021年   13篇
  2020年   40篇
  2019年   55篇
  2018年   2219篇
  2017年   2137篇
  2016年   1621篇
  2015年   148篇
  2014年   147篇
  2013年   253篇
  2012年   254篇
  2011年   716篇
  2010年   858篇
  2009年   453篇
  2008年   658篇
  2007年   1166篇
  2006年   79篇
  2005年   407篇
  2004年   464篇
  2003年   381篇
  2002年   141篇
  2001年   11篇
  2000年   28篇
  1999年   15篇
  1998年   3篇
  1997年   19篇
  1996年   3篇
  1995年   5篇
  1994年   2篇
  1993年   4篇
  1992年   6篇
  1991年   10篇
  1990年   4篇
  1989年   2篇
  1988年   1篇
  1987年   2篇
  1986年   1篇
  1985年   1篇
  1984年   1篇
  1983年   4篇
  1982年   11篇
  1981年   2篇
  1980年   1篇
  1979年   2篇
  1976年   2篇
  1958年   1篇
  1934年   1篇
  1933年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Coconut oil has been used by the people of Kerala as a cooking medium for several decades. Due to its alleged hypercholesterolemic activity, general population in recent times is shifting to cooking oils rich in polyunsaturated fats, the most popular being sunflower oil. The effect of long-term consumption of sunflower oil on oxidative stress in humans is not well investigated. We studied oxidative stress among coronary artery disease (CAD) patients who were consuming coconut oil or sunflower oil as a part of their routine diet. Men, aged 35–70 years, with established CAD, who presented to the hospital for routine cardiac evaluations, were enrolled in this observational study. Group 1 and 2 consisted of 73 and 80 subjects consuming coconut oil and sunflower oil respectively for over a period of 2 years. Lipid profile and parameters for oxidative stress were evaluated among them. Conventional lipid parameters did not differ significantly between the two groups. Mean vitamin C concentration was significantly reduced for subjects on sunflower oil compared to those consuming coconut oil (P = 0.044). Malondialdehyde was higher for sunflower oil consumers compared to coconut oil consumers (P < 0.0001). Other parameters such as oxidized LDL, GSH, GPx and SOD were not found to be significantly different between the two groups. The results of the present study show that coconut oil did not induce hypercholesterolemia compared to sunflower oil. On the other hand, sunflower oil group had elevated oxidative stress compared to coconut oil group.  相似文献   
92.
93.
Abnormal lipid profile is often found in women with Polycystic Ovary Syndrome. To assess the impact of abnormal lipid profile on atherosclerosis in young Polycystic Ovary Syndrome women, carotid intima-media thickness as judged by B-mode ultrasonography were done in 30 young (18–35 yrs) Polycystic Ovary Syndrome women and in similarly age-matched 30 apparently healthy controls. Compared to controls, young Polycystic Ovary Syndrome women had significantly elevated serum total cholesterol, triglyceride and LDL-C levels and carotid intima-media thickness. HDL-C level did not differ significantly between two groups of women. In Polycystic Ovary Syndrome women carotid intima-media thickness was positively correlated with serum total cholesterol, triglyceride and LDL-C and negatively correlated with serum HDL-C. Our study suggests that even young Polycystic Ovary Syndrome women are prone to atherosclerosis from early age.  相似文献   
94.
This study deals with the effects of freeze dried rhizome powder of Curcuma longa (C. longa) dissolved in milk on normal as well as diabetic models. Diabetes of type II and type I was within 3 days of a single administration of doses of 45 and 65 mg kg−1 of streptozotocin respectively. Various parameters such as blood glucose levels, triglycerides, total cholesterol, high density lipoprotein, very low density lipoprotein, low density lipoprotein, serum glutamic oxaloacetic transaminase, serum glutamic pyruvate transaminase, alkaline phosphatase, creatinine, hemoglobin, urine protein and urine sugar in addition to body weight were taken in to consideration and were analyzed after administration of variable doses of rhizome powder. The dose of 200 mg kg−1 was identified as the most effective dose as it increased HDL, Hb and bw (P<0.05) with significant decrease in the levels of blood glucose, lipid profile and hepatoprotective enzymes (P<0.001).  相似文献   
95.
The present study evaluated the plausible role of circulating biomarkers in immune pathogenesis of chronic hepatitis considered a priority in clinical hepatology. Total viral load of chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) patients was quantified and correlation studies were performed with circulating levels of Th1/Th2 cytokines; C reactive protein and circulating nucleosomes; glutathione reductase (GR) and superoxide dismutase. To our knowledge, the study is first among its kind that validates strong positive correlation of viral load with IL-4, IL-6, GR in HBV and IL-6, IL-10, GR in HCV infections. Although, multi-centric studies including large cohorts are required for translating our findings to clinical practice, however, role of these biomarkers with potential diagnostic or prognostic significance might be helpful in clinical assessment of high-risk individuals, thereby, designing interventional strategies, towards development of personalized medicare. The results of our study also offer valuable insights of immune signaling mediators engaged in development of hepatocellular carcinoma.  相似文献   
96.
In previous studies, we have reported first in vivo evidence of copper deposition in the choroid plexus, cognitive impairments, astrocytes swelling (Alzheimer type II cells) and astrogliosis (increase in number of astrocytes), and degenerated neurons coupled with significant increase in the hippocampus copper and zinc content in copper-intoxicated Wistar rats. Nonetheless, hippocampus iron levels were not affected by chronic copper-intoxication. Notwithstanding information on distribution of copper, zinc and iron status in different regions of brain due to chronic copper exposure remains fragmentary. In continuation with our previous study, the aim of this study was to investigate the effects of intraperitoneally injected copper lactate (0.15 mg Cu/100 g body weight) daily for 90 days on copper, zinc and iron levels in different regions of the brain using atomic absorption spectrophotometry. Copper-intoxicated group showed significantly increased cortex, cerebellum and striatum copper content (76, 46.8 and 80.7 % increase, respectively) compared to control group. However, non-significant changes were observed for the zinc and iron content in cortex, cerebellum and striatum due to chronic copper exposure. In conclusion, the current study demonstrates that chronic copper toxicity causes differential copper buildup in cortex, cerebellum and striatum region of central nervous system of male Wistar rats; signifying the critical requirement to discretely evaluate the effect of copper neurotoxicity in different brain regions, and ensuing neuropathological and cognitive dysfunctions.  相似文献   
97.
98.
Existing literature has generally focused on organizational memory (OM) and workforce agility. Yet, less concentration has been devoted to the impact of workforce agility on OM. This research proposed a model that studies the impact of workforce agility on declarative OM and procedural OM. The model focused on aspects related to proactivity, adaptability, and resiliency. The study targeted the cell phone industry in Jordan. The study sample included 430 individuals involved in managerial and professional knowledge positions in mobile communications companies in Jordan. The article concluded that a proactive workforce has a significant impact on declarative OM and proactivity also improves procedural OM. Consequently, practical implications for managers, and suggested future research are presented.  相似文献   
99.
Experimental model of chronic renal failure in rats have been described by many authors and has also been widely used in various studies. Many of these methods used highly sophisticated instruments which was difficult in our settings. The resection model was ideal in our experimental set-up, but this model had the risk of excessive bleeding and hypovolemia. In our study we used a combination of partial resection and ligation of the renal artery to create two models of stable uremia A and Moderate uremia B. Severe uremia. Both these models were compared with a sham operated group which served as controls. Following surgical procedure, the development of uremia was monitored by serial estimation of blood urea and serum creatinine levels that were measured at regular intervals (bi-weekly). From two weeks onwards the animals in the experimental group showed a significant elevation in the serum urea levels and a consistent elevation in the serum creatinine levels upto eight weeks when compared to the animals in the sham operated group. We established a modified method of producing renal failure which can be maintained for a period of six weeks. This model is simple, reproducible and less complicated that can be used for several studies relating to renal failure in the field of research.  相似文献   
100.
    
This paper aims to provide new insights to debates on group privacy, which can be seen as part of a social turn in privacy scholarship. Research is increasingly showing that the classic individualistic understanding of privacy is insufficient to capture new problems in algorithmic and online contexts. An understanding of privacy as an “interpersonal boundary-control process” (Altman, The environment and social behavior, Brooks and Cole, Monterey, 1975) framing privacy as a social practice necessary to sustain intimate relationships is gaining ground. In this debate, my research is focused on what I refer to as “self-determined groups” which can be defined as groups whose members consciously and willingly perceive themselves as being part of a communicative network. While much attention is given to new forms of algorithmically generated groups, current research on group privacy fails to account for the ways in which self-determined groups are affected by changes brought about by new information technologies. In an explorative case study on self-organized therapy groups, I show how these groups have developed their own approach to privacy protection, functioning on the basis of social practices followed by all participants. This informal approach was effective in pre-digital times, but online, privacy threats have reached a new level extending beyond the scope of a group’s influence. I therefore argue that self-determined sensitive topic groups are left facing what I present as a dilemma: a tension between the seemingly irreconcilable need for connectivity and a low threshold, on the one hand, and the need for privacy and trust, on the other. In light of this dilemma, I argue that we need new sorts of political solutions.  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