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21.
Singh PP Chandra A Mahdi F Roy A Sharma P 《Indian journal of clinical biochemistry : IJCB》2010,25(3):225-243
The antioxidants are essential molecules in human system but are not miracle molecules. They are neither performance enhancers
nor can prevent or cure diseases when taken in excess. Their supplemental value is debateable. In fact, many high quality
clinical trials on antioxidant supplement have shown no effect or adverse outcomes ranging from morbidity to all cause mortality.
Several Chochrane Meta-analysis and Markov Model techniques, which are presently best available statistical models to derive
conclusive answers for comparing large number of trials, support these claims. Nevertheless none of these statistical techniques
are flawless. Hence, more efforts are needed to develop perfect statistical model to analyze the pooled data and further double
blind, placebo controlled interventional clinical trials, which are gold standard, should be implicitly conducted to get explicit
answers. Superoxide dismutase (SOD), glutathione peroxidase and catalase are termed as primary antioxidants as these scavenge
superoxide anion and hydrogen peroxide. All these three enzymes are inducible enzymes, thereby inherently meaning that body
increases or decreases their activity as per requirement. Hence there is no need to attempt to manipulate their activity nor
have such efforts been clinically useful. SOD administration has been tried in some conditions especially in cancer and myocardial
infarction but has largely failed, probably because SOD is a large molecule and can not cross cell membrane. The dietary antioxidants,
including nutrient antioxidants are chain breaking antioxidants and in tandem with enzyme antioxidants temper the reactive
oxygen species (ROS) and reactive nitrogen species (RNS) within physiological limits. Since body is able to regulate its own
requirements of enzyme antioxidants, the diet must provide adequate quantity of non-enzymic antioxidants to meet the normal
requirements and provide protection in exigent condition. So far, there is no evidence that human tissues ever experience
the torrent of reactive species and that in chronic conditions with mildly enhanced generation of reactive species, the body
can meet them squarely if antioxidants defense system in tissues is biochemically optimized. We are not yet certain about
optimal levels of antioxidants in tissues. Two ways have been used to assess them: first by dietary intake and second by measuring
plasma levels. Lately determination of plasma/serum level of antioxidants is considered better index for diagnostic and prognostic
purposes. The recommended levels for vitamin A, E and C and beta carotene are 2.2–2.8 μmol/l; 27.5–30 μmol/l; 40–50 μmol/l
and 0.4–0.5 μmol/l, respectively. The requirement and recommended blood levels of other dietary antioxidants are not established.
The resolved issues are (1) essential to scavenge excess of radical species (2) participants in redox homeostasis (3) selective
antioxidants activity against radical species (4) there is no universal antioxidant and 5) therapeutic value in case of deficiency.
The overarching issues are (1) therapeutic value as adjuvant therapy in management of diseases (2) supplemental value in developing
population (3) selective interactivity of antioxidant in different tissues and on different substrates (4) quantitative contribution
in redox balance (5) mechanisms of adverse action on excess supplementation (6) advantages and disadvantages of prooxidant
behavior of antioxidants (7) behavior in cohorts with polymorphic differences (8) interaction and intervention in radiotherapy,
diabetes and diabetic complications and cardiovascular diseases (9) preventive behavior in neurological disorders (10) benefits
of non-nutrient dietary antioxidants (11) markers to assess optimized antioxidants status (12) assessment of benefits of supplementation
in alcoholics and heavy smokers. The unresolved and intriguing issues are (1) many compounds such as vitamin A and many others
possessing both antioxidant and non-antioxidant properties contribute to both the activities in vivo or exclusively only to
non-antioxidant activity and (2) since human tissues do not experience the surge of FR, whether there is any need to develop
stronger synthetic antioxidants. Theoretically such antioxidants may do more harm than good. 相似文献
22.
美国现行的教育体制构建在两个理想的前提上,一是必须保证所有的人接受基础教育,但由于各州经济状况的不同而导致基础教育发展不平衡;一是必须保证所有人都有接受高等教育的权利和机会。美国教育体制下存在公助和私助两种办学模武,他们更强调教会学生创新和独立思考,一些学校正进行改革试验,并取得了一定成效。 相似文献
23.
刘静芳 《华东师范大学学报(哲学社会科学版)》2004,36(5):37-42
张岱年是“解析的唯物论”的代表 ,但他的“本体”观既不同于强调解析的清华学派哲学家 ,又不同于当时的新唯物论者。张岱年所谓的“本体”是“理”与“物”的统一、“本”与“至”的统一 ,是总结中西“本体”观念基础上的一种综合创造。这种创造体现了张岱年超越清华学派和新唯物论的尝试 相似文献
24.
胡俊荣 《华南师范大学学报(社会科学版)》2004,(6):121-124
近年来,许多发达国家和发展中国家已经清楚地意识到图书馆国际化对本国图书馆发展的意义及构成的挑战,纷纷制定各种战略规划以促进本国图书馆向着国际化的方向发展。因此,对我国图书馆国际化进行研究,尤其是对处于改革开放前沿、位居我国经济强省地位并正在加快建设化大省和教育大省的广东之图书馆的国际化发展战略进行深入系统的研究,就显得十分紧迫和必要。该组章从实施数字参考咨询服务、推进图书馆国际化进程,图书馆国际化人才应具备的素质、培养图书馆国际化人才的措施,更新观念、强化图书馆国际化意识等诸多视角,论述了图书馆国际化的重要意义,提出了图书馆国际化的发展策略。 相似文献
25.
熊鹰 《华南师范大学学报(社会科学版)》2004,6(6):126-128,141
作为我国对外开放的前沿阵地,广东经济最先与国际经济融为一体,现在又提出建设文化大省的伟大事业。图书馆事业是文化事业的重要组成部分,因此,在建设文化大省过程中,探讨广东图书馆的国际化问题有重要的现实意义。本文拟从强化意识方面谈谈看法。 相似文献
26.
ABSTRACT: This paper argues that the introduction of access agreements following the establishment of the Office for Fair Access (OFFA) has consolidated how English higher education institutions (HEIs) position themselves in the marketplace in relation to widening participation. However, the absence of a national bursary scheme has led to obfuscation rather than clarification from the perspective of the consumer. This paper analyses OFFA's 2008 monitoring report and a sample of twenty HEIs' original 2006 and revised or updated access agreements (2008) to draw conclusions about the impact of these agreements on notions of 'fair access' and widening participation. The authors conclude that, unsurprisingly in an increasingly market-driven system, institutions use access agreements primarily to promote enrolment to their own programmes rather than to promote system-wide objectives. As a consequence of this marketing focus, previous differences between pre-1992 and post-1992 institutions in relation to widening participation and fair access are perpetuated, leading to both confusion for consumers and an inequitable distribution of bursary and other support mechanisms for the poorest applicants to HE. 相似文献
27.
28.
课程的开发受到诸多因素的制约,价值观和课程目标的确定是其中的两个重要因素.由于各个国家的国情不同,课程设置存在一定的差异.本文试图介绍英国国家课程的价值观和课程目标,以期对我国基础教育的课程开发起到一定的借鉴作用. 相似文献
29.
30.
何慎怡 《深圳信息职业技术学院学报》1999,(1)
段玉裁的“以声为义”说体现在两个方面:“依据声旁,由声求义”;“不限形体,于音得义”。本文就《说文解字注》中的声训条例,对“以声为义”说及其得失作了论述。 相似文献