全文获取类型
收费全文 | 40049篇 |
免费 | 405篇 |
国内免费 | 20篇 |
专业分类
教育 | 29163篇 |
科学研究 | 3502篇 |
各国文化 | 337篇 |
体育 | 2974篇 |
综合类 | 11篇 |
文化理论 | 650篇 |
信息传播 | 3837篇 |
出版年
2021年 | 289篇 |
2020年 | 494篇 |
2019年 | 716篇 |
2018年 | 2962篇 |
2017年 | 2896篇 |
2016年 | 2403篇 |
2015年 | 668篇 |
2014年 | 788篇 |
2013年 | 5425篇 |
2012年 | 866篇 |
2011年 | 1446篇 |
2010年 | 1364篇 |
2009年 | 968篇 |
2008年 | 1258篇 |
2007年 | 1725篇 |
2006年 | 600篇 |
2005年 | 863篇 |
2004年 | 963篇 |
2003年 | 790篇 |
2002年 | 566篇 |
2001年 | 550篇 |
2000年 | 626篇 |
1999年 | 500篇 |
1998年 | 313篇 |
1997年 | 341篇 |
1996年 | 378篇 |
1995年 | 296篇 |
1994年 | 325篇 |
1993年 | 273篇 |
1992年 | 416篇 |
1991年 | 423篇 |
1990年 | 393篇 |
1989年 | 407篇 |
1988年 | 379篇 |
1987年 | 358篇 |
1986年 | 365篇 |
1985年 | 417篇 |
1984年 | 341篇 |
1983年 | 351篇 |
1982年 | 283篇 |
1981年 | 280篇 |
1980年 | 294篇 |
1979年 | 384篇 |
1978年 | 298篇 |
1977年 | 261篇 |
1976年 | 223篇 |
1975年 | 197篇 |
1974年 | 190篇 |
1973年 | 182篇 |
1971年 | 182篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
Roberts J. Kyle Henson Robin K. Tharp Barbara Z. Moreno Nancy P. 《Journal of Science Teacher Education》2001,12(3):199-213
Journal of Science Teacher Education - 相似文献
962.
The purpose of this article is to report findings from an ethnographic study that focused on the co‐development of science literacy and academic identity formulation within a third‐grade classroom. Our theoretical framework draws from sociocultural theory and studies of scientific literacy. Through analysis of classroom discourse, we identified opportunities afforded students to learn specific scientific knowledge and practices during a series of science investigations. The results of this study suggest that the collective practice of the scientific conversations and activities that took place within this classroom enabled students to engage in the construction of communal science knowledge through multiple textual forms. By examining the ways in which students contributed to the construction of scientific understanding, and then by examining their performances within and across events, we present evidence of the co‐development of students' academic identities and scientific literacy. Students' communication and participation in science during the investigations enabled them to learn the structure of the discipline by identifying and engaging in scientific activities. The intersection of academic identities with the development of scientific literacy provides a basis for considering specific ways to achieve scientific literacy for all students. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 1111–1144, 2004 相似文献
963.
964.
Urinary citric acid and calcium levels have been estimated in the urine of 20 normal healthy persons as well as 12 urinary
stone patients. Inhibition efficiency of these urine samples towards the mineralisation of urinary stone forming minerals,
viz., calcium phosphate, oxalate or carbonate, has been studied in an experimental model. Statistical correlation of the above
data has been made by computing the coefficient of determination and unexplained variance. Clinico-biochemical indexing of
calcium urolithiasis risk factor has been attempted in the light of the data. 相似文献
965.
966.
967.
K. A. Faseehuddin Shakir Basavaraj Madhusudhan 《Indian journal of clinical biochemistry : IJCB》2007,22(1):117-121
Rats fed with hypercholesterolemic diet showed a significant increase in serum total—cholesterol, liver homogenate total-cholesterol,
HDL-cholesterol and changed LDL-cholesterol, and HDL/LDL ratio in comparison to control. Flaxseedchutney (FC) supplemented diet (15%, w/w) was found to be more effective in restoring lipid profile changes in rats fed with cholesterol,
(1.0%). The activities of serum marker enzymes glutamate oxaloacetate transminase (GOT), glutamate pyruvate transaminase (GPT)
and alkaline phosphatase (ALP) were elevated significantly in carbon tetrachloride induced rats. Administration of flaxseedchutney (15%, w/w) resulted in depletion of serum marker enzymes and exhibited recoupment thus showing significant hepatoprotective
effect. It was observed that flaxseedchutney supplemented diet could lower the serum cholesterol and as a potential source of antioxidants it could exert protection against
hepatotoxic damage induced by carbon tetrachloride (CCl4) in rats. 相似文献
968.
Maintaining the reversibility of foldings: Making the ethics (politics) of information technology visible 总被引:1,自引:0,他引:1
Lucas D. Introna 《Ethics and Information Technology》2007,9(1):11-25
This paper will address the question of the morality of technology. I believe this is an important question for our contemporary
society in which technology, especially information technology, is increasingly becoming the default mode of social ordering.
I want to suggest that the conventional manner of conceptualising the morality of technology is inadequate – even dangerous.
The conventional view of technology is that technology represents technical means to achieve social ends. Thus, the moral
problem of technology, from this perspective, is the way in which the given technical means are applied to particular (good
or bad) social ends. In opposition to this I want to suggest that the assumed separation, of this approach, between technical
means and social ends are inappropriate. It only serves to hide the most important political and ethical dimensions of technology.
I want to suggest that the morality of technology is much more embedded and implicit than such a view would suggest. In order
to critique this approach I will draw on phenomenology and the more recent work of Bruno Latour. With these intellectual resources
in mind I will propose disclosive ethics as a way to make the morality of technology visible. I will give a brief account
of this approach and show how it might guide our␣understanding of the ethics and politics of technology by considering two
examples of contemporary information technology: search engines and plagiarism detection systems. 相似文献
969.
J. Baxi Kavita Sharma Rajbala Asha Mehta A. K. Pendse P. P. Singh 《Indian journal of clinical biochemistry : IJCB》1994,9(1):47-49
Evaluation of serum SOD and MDA level was done in 21 first episode renal stone formers, 9 recurrent stone formers, 20 patients with obstructive uropathy other than urolithiasis and 12 patients with urinary infection. Twenty-two healthy volunteers were taken as controls. The level of SOD in respective groups was 2.12±0.84, 2.78±0.85, 1.42±0.31, 1.98±0.70 and 2.32±0.62 units/ml and of MDA was 2.61±1.07, 2.69±1.15, 1.65±0.33, 1.33±0.34 and 1.55±0.48 n mol/ml respectively. The results indicate increased peroxidative stressin nephrolithiasis only. Since SOD level was normal in all groups, this increased peroxidative stress in nephrolithiasis should be due to factors other than this one. 相似文献
970.
Prof. Dr. Michael Dowling 《科研管理》2004,25(Z1):106-111
通过对美国及德国的十多年研究表明,对于创新及合作网络的投资有利于促进高技术行业企业不断进步和发展.这些高技术行业包括电信、电脑设备及生物工艺的行业.研究表明政府政策在促进竞争及支持地区合作网络发展中起到了极其重要的作用. 相似文献