全文获取类型
收费全文 | 21620篇 |
免费 | 113篇 |
国内免费 | 7篇 |
专业分类
教育 | 15556篇 |
科学研究 | 2375篇 |
各国文化 | 335篇 |
体育 | 1088篇 |
综合类 | 4篇 |
文化理论 | 455篇 |
信息传播 | 1927篇 |
出版年
2021年 | 88篇 |
2020年 | 141篇 |
2019年 | 195篇 |
2018年 | 2420篇 |
2017年 | 2366篇 |
2016年 | 1840篇 |
2015年 | 291篇 |
2014年 | 312篇 |
2013年 | 1804篇 |
2012年 | 439篇 |
2011年 | 971篇 |
2010年 | 1044篇 |
2009年 | 613篇 |
2008年 | 898篇 |
2007年 | 1408篇 |
2006年 | 255篇 |
2005年 | 573篇 |
2004年 | 645篇 |
2003年 | 502篇 |
2002年 | 254篇 |
2001年 | 161篇 |
2000年 | 213篇 |
1999年 | 163篇 |
1998年 | 88篇 |
1997年 | 107篇 |
1996年 | 79篇 |
1993年 | 81篇 |
1992年 | 140篇 |
1991年 | 161篇 |
1990年 | 156篇 |
1989年 | 161篇 |
1988年 | 121篇 |
1987年 | 118篇 |
1986年 | 123篇 |
1985年 | 165篇 |
1984年 | 133篇 |
1983年 | 122篇 |
1982年 | 102篇 |
1981年 | 81篇 |
1980年 | 94篇 |
1979年 | 145篇 |
1978年 | 94篇 |
1977年 | 94篇 |
1976年 | 80篇 |
1975年 | 83篇 |
1974年 | 96篇 |
1973年 | 82篇 |
1972年 | 69篇 |
1971年 | 76篇 |
1968年 | 76篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
73.
74.
75.
Soma Gupta K. K. Singh V. J. Vyas V. N. Chaturvedi M. V. R. Reddy B. C. Harinath 《Indian journal of clinical biochemistry : IJCB》2000,15(1):52-55
Oxidative stress was studied by estimating plasma levels of malondialdehyde (MDA), beta carotene, vitamin E and erythrocytic
superoxide dismutase(E-SOD) activity in 50 cases of carcinoma of upper digestive tract which included carcinoma of oral cavity,
pharynx and oesophagus. While plasma MDA level was found to be increased (3.5±1.0 nmole/ml), a significant decrease in beta
carotene (81.2±14.5mg%), vitamin E (8.5±1.1 mg/L) level and E-SOD activity (657.0±80.6 U/G Hb) were observed in carcinoma
of upper digestive tract. Patients were treated with radiotherapy which itself was toxic enough and produced its deleterious
effects by generation of reactive oxygen species (ROS). As antioxdiants can detoxify ROS, beneficial effect if any, of antioxidant
administration during radiotherapy was studied in two groups of patients, group A (n=5, supplemented with antioxidants) and
group B (n=5, without antioxidant supplementation). Plasma MDA level was found to be elevated in both the groups but the increase
in group B was significant, compared to pretreatment level. Further, body weight was found to be significantly decreased in
group B patients, which was maintained in group A patients. Moreover, group A patients showed significant elevation in beta
carotene concentration, thus showing beneficial effect of administration of antioxidants during radiotherapy without disturbing
the desirable therapeutic effect of radiotherapy. 相似文献
76.
77.
Anders Albrechtslund 《Ethics and Information Technology》2007,9(1):63-72
This article offers a discussion of the connection between technology and values and, specifically, I take a closer look at
ethically sound design. In order to bring the discussion into a concrete context, the theory of Value Sensitive Design (VSD)
will be the focus point. To illustrate my argument concerning design ethics, the discussion involves a case study of an augmented
window, designed by the VSD Research Lab, which has turned out to be a potentially surveillance-enabling technology. I call
attention to a “positivist problem” that has to do with the connection between the design context and the use context, which
VSD seems to presuppose, and I argue that it is necessary to clearly distinguish between the two, since the designers’ intentions
do not always correspond with the users’ practice; in fact, the relation between design and use is very complex and principally
unpredictable. Thus, a design theory must accept that foresight is limited to anticipation rather than prediction. To overcome
the positivist problem, I suggest a phenomenological approach to technology inspired by Don Ihde’s concept of multistability.
This argument, which is general in nature and thus applies to any theory of design ethics, is intended as a constructive criticism,
which can hopefully contribute to the further development of design ethics. 相似文献
78.
79.
80.