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   3024篇
  免费   8篇
教育   2067篇
科学研究   538篇
体育   110篇
综合类   7篇
文化理论   62篇
信息传播   248篇
  2023年   2篇
  2022年   5篇
  2021年   16篇
  2020年   2篇
  2019年   6篇
  2018年   62篇
  2017年   102篇
  2016年   170篇
  2015年   118篇
  2014年   56篇
  2013年   80篇
  2012年   158篇
  2011年   170篇
  2010年   86篇
  2009年   32篇
  2008年   67篇
  2007年   61篇
  2006年   52篇
  2005年   690篇
  2004年   472篇
  2003年   302篇
  2002年   133篇
  2001年   66篇
  2000年   34篇
  1999年   27篇
  1998年   5篇
  1997年   5篇
  1996年   5篇
  1995年   3篇
  1994年   1篇
  1993年   1篇
  1992年   2篇
  1991年   5篇
  1990年   5篇
  1989年   4篇
  1988年   2篇
  1987年   4篇
  1986年   1篇
  1985年   1篇
  1984年   2篇
  1982年   4篇
  1981年   1篇
  1980年   2篇
  1978年   1篇
  1976年   2篇
  1974年   2篇
  1971年   1篇
  1970年   2篇
  1959年   1篇
  1923年   1篇
排序方式: 共有3032条查询结果,搜索用时 31 毫秒
81.
Hypertension is the most common cardiovascular risk factor. Lipoprotein(a) [Lp(a)], inflammation, oxidative stress and chronic kidney disease (CKD) exacerbate the response to tissue injury and acts as markers of the vascular disease, especially in glomerulosclerosis. We compared the clinical characteristics of 138 non-diabetes hypertensive women (ndHT) patients with 417 non-diabetes normotensive subjects and tested the association of hypertension with Lp(a), inflammation, CKD and oxidative stress by using multiple logistic regression. BP, BMI, waist circumference, creatinine, Lp(a), inflammation and malondialdehyde levels were significantly higher and CKD state in the ndHT patients (p < 0.05). Multiple logistic regression showed hypertension associated with increased Lp(a), inflammation, ORs and 95 % CIs were 2.52 (1.33, 4.80), 2.75 (1.44, 5.27) after adjusting for their covariates. Elevated serum Lp(a) and inflammation levels concomitants with increased oxidative stress and CKD were the major risk factors associated with hypertension and implications for the increased risk of HT and vascular disease.  相似文献   
82.

Introduction

Extremely high glucose concentrations have been shown to interfere with creatinine assays especially with Jaffe method in peritoneal dialysate. Because diabetes is the fastest growing chronic disease in the world, laboratories study with varying glucose concentrations. We investigated whether different levels of glucose spiked in serum interfere with 21 routine chemistry and thyroid assays at glucose concentrations between 17-51 mmol/L.

Materials and methods

Baseline (group I) serum pool with glucose concentration of 5.55 (5.44-5.61) mmol/L was prepared from patient sera. Spiking with 20% dextrose solution, sample groups were obtained with glucose concentrations: 17.09, 34.52, and 50.95 mmol/L (group II, III, IV, respectively). Total of 21 biochemistry analytes and thyroid tests were studied on Abbott c8000 and i2000sr with commercial reagents. Bias from baseline value was checked statistically and clinically.

Results

Creatinine increased significantly by 8.74%, 31.66%, 55.31% at groups II, III, IV, respectively with P values of < 0.001. At the median glucose concentration of 50.95 mmol/L, calcium, albumin, chloride and FT4 biased significantly clinically (-0.85%, 1.63%, 0.65%, 7.4% with P values 0.138, 0.214, 0.004, < 0.001, respectively). Remaining assays were free of interference.

Conclusion

Among the numerous biochemical parameters studied, only a few parameters are affected by dramatically increased glucose concentration. The creatinine measurements obtained in human sera with the Jaffe alkaline method at high glucose concentrations should be interpreted with caution. Other tests that were affected with extremely high glucose concentrations were calcium, albumin, chloride and FT4, hence results should be taken into consideration in patients with poor diabetic control.Key words: assay interference, glucose interference, preanalytical phase, creatinine, Jaffe kinetic assay, thyroid function tests  相似文献   
83.
84.
This paper aims to determine the factors affecting the decisions of both male and female secondary school pupils whether or not to pursue undergraduate studies in Computing. It is based on research conducted in Greece, on a sample of 248 pupils, 135 of whom were female. All were aged 17 and about to decide on their future undergraduate studies. Questionnaires were used, addressing issues in the following four main categories: a) the reasons pupils chose/rejected Computing, b) how family and friends, the media and the school environment contribute to their decision, c) how pupils perceived their future after studying Computing and d) how pupils perceived the profile of a computer professional in terms of gender.
Maria KordakiEmail:
  相似文献   
85.
Basic subjects in medical education, such as anatomy, are often taught through teaching formats that do not always sufficiently demonstrate the relevance of this basic information for clinical practice. Accordingly, it is a recent trend in anatomy education to link anatomical information more explicitly to clinical practice. This article presents an online video platform (Tuebingen’s Sectio Chirurgica [TSC]) as one means of explicitly integrating preclinical anatomical knowledge and clinical application. The purpose of the study presented here was to examine the effects of videos through which medical students were educated about Anterior Cruciate Ligament reconstruction. A TSC video about this surgical procedure was compared to a video with a traditional lecture providing the identical information. Participants (n = 114) perceived the TSC video to be superior in comprehensibility of the presentation (P = 0.003) and conceivability of the surgical procedure (P = 0.027), and to be more entertaining (P < 0.001). Moreover, participants in the TSC condition acquired more clinical knowledge than in the lecture condition (P = 0.043) but did not differ in their acquisition of anatomical knowledge. Mediation analyses indicated that the effect on the acquisition of clinical knowledge was mediated by comprehensibility, conceivability, and entertainment. These findings are discussed regarding their implications for medical education in terms of contributing to the general trend of linking preclinical anatomical knowledge to clinical application. A discussion about the limitations of the study and suggestions for future research are also provided.  相似文献   
86.
IPv4, the workhorse protocol of the currently popular TCP/ IP protocol suite, is fast becoming obsolete. The exponential growth of the Internet is the main reason that has required the creation of the next generation of Internet Protocol-IPv6. IPv6 is much more flexible and promises to take care of the address space and security issues in the foreseeable future. Part 1 of the paper lays the foundation of the various issues involved in designing the Internet Protocol and motivates the need for an upgraded version of this protocol.  相似文献   
87.
88.
In many Western science systems, funding structures increasingly stimulate academic research to contribute to practical applications, but at the same time the rise of bibliometric performance assessments have strengthened the pressure on academics to conduct excellent basic research that can be published in scholarly literature. We analyze the interplay between these two developments in a set of three case studies of fields of chemistry in the Netherlands. First, we describe how the conditions under which academic chemists work have changed since 1975. Second, we investigate whether practical applications have become a source of credibility for individual researchers. Indeed, this turns out to be the case in catalysis, where connecting with industrial applications helps in many steps of the credibility cycle. Practical applications yield much less credibility in environmental chemistry, where application-oriented research agendas help to acquire funding, but not to publish prestigious papers or to earn peer recognition. In biochemistry practical applications hardly help in gaining credibility, as this field is still strongly oriented at fundamental questions. The differences between the fields can be explained by the presence or absence of powerful upstream end-users, who can afford to invest in academic research with promising long term benefits.  相似文献   
89.
90.
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