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   568篇
  免费   2篇
  国内免费   1篇
教育   261篇
科学研究   267篇
各国文化   5篇
体育   2篇
文化理论   4篇
信息传播   32篇
  2023年   2篇
  2022年   7篇
  2021年   19篇
  2020年   5篇
  2019年   10篇
  2018年   36篇
  2017年   25篇
  2016年   24篇
  2015年   29篇
  2014年   28篇
  2013年   55篇
  2012年   16篇
  2011年   20篇
  2010年   25篇
  2009年   33篇
  2008年   24篇
  2007年   19篇
  2006年   31篇
  2005年   23篇
  2004年   16篇
  2003年   28篇
  2002年   12篇
  2001年   9篇
  2000年   8篇
  1999年   6篇
  1998年   12篇
  1997年   8篇
  1996年   3篇
  1995年   6篇
  1994年   4篇
  1993年   5篇
  1992年   5篇
  1991年   1篇
  1990年   2篇
  1989年   2篇
  1987年   1篇
  1986年   2篇
  1985年   1篇
  1983年   2篇
  1979年   1篇
  1977年   1篇
  1976年   2篇
  1975年   1篇
  1973年   1篇
  1962年   1篇
排序方式: 共有571条查询结果,搜索用时 296 毫秒
231.
Elastase activity was found to be significantly increased in periodontitis (0.872±0.4270 absorbance units/mg protein, mean±S. D., 1.05±0.61 units/ml saliva), gingivitis (0.772±0.416 units/mg protein, 1.515±0.952 units/ml) and diabetes (0.549±0.286 units/mg protein, 1.20±0.769 units/ml) compared to normals (0.255±0.089) units/mg protein, 0.264±0.079 units/ml). Chymotryptic activity was not found to be increased in these disease conditions over the normal level (0.284±0.096 units/mg protein). Aminopeptidase activity was elevated only in periodontitis (0.670+0.140 units/mg protein) compared to normals (0.349±0.100 units/mg protein). Trypsin-like activity was also found to be significantly raised in periodontitis compared to normals when Pro-Phe-Arg-p-nitroanilide (0.666±0.204 units/mg protein), Ile-Pro-Arg-p-nitroanilide (1.59±0.260 units/mg protein) and Pyroglu-Pro-Arg-p-nitroanilide (1.82±0.380 units/mg protein) were used as substrates. The normal values with these three substrates were respectively, 0.454±0.110, 1.04±0.231 and 1.15±0.312 units/mg protein. Total protein level in saliva was found to be significantly elevated in gingivitis (209±66.8 mg/dl) and diabetes (204±68.0) compared to normal values (107±20.7). Increase in periodontitis was marginal (127±28.3 mg/dl). Expression of proteolytic activities normalized to protein level was useful in differential diagnosis. Increase in elastase level in saliva is not a specific marker for periodontal diseases.  相似文献   
232.
Serum lipid profile, apolipoprotein-B (apo-B), malondialdehyde levels(MDA) and superoxide dismutase (SOD) activity were assessed in 12 cases of xanthelasma with and without coronary artery disease (CAD)/hypertension (HTN) and results are compared with healthy controls. Dyslipidemia was found in 65% cases of xanthelasma as compared to 20% healthy controls. Xanthelasma patients had significantly high malondialdehyde (MDA) levels (p<0.01) and significantly decreased (p<0.05) SOD activity as compared to controls. Among xanthelasma patients, xanthelasma with CAD/HTN showed higher total cholesterol (236±32.7 vs 188±24.7 mg/dl), low density lipoprotein cholesterol (157±35.5 vs 113±16 mg/dl) and Apo-B (120.5±9.4 vs 114±19.2 mg/dl) levels as compared to xanthelasma without CAD/HTN. Results of our study indicate that xanthelasma patients with increased apo-B, MDA and decreased SOD need cardiovascular monitoring.  相似文献   
233.
234.
235.
This article describes a classroom tool to teach the impact of supply chain disruptions and mitigation strategies based on information sharing and collaboration. The tool is an adaptation of the Beer Distribution Game, is easy to play, and can be hosted online or on local servers. The game considers several scenarios based on the location of the disruptions (i.e., upstream or downstream) and the information available to supply chain partners. Students play the roles of managers who make ordering decisions in a serial supply chain and experience decision‐making under disruptions.  相似文献   
236.
The concept of issues management is gaining the increasing attention of both researchers and practitioners in the field of strategic planning. Issues management—which is concerned with the identification, analysis, probability, and timing of a developing issue and with the organizational response—can spell the difference between the success and the failure of the planning effort. This paper delineates the attempt of a major public university to integrate issues management into the institutional strategic planning process. The intent is to make issues management an ongoing and systematic organizational exercise.Paper presented at the Twenty-fifth Annual Forum of the Association for Institutional Research, Portland, April 28–May 1, 1985.  相似文献   
237.
238.
Arvind Kumar 《Resonance》2006,11(12):10-20
Newton’s epochal work on dynamics and gravitation sometimes tends to eclipse his great contributions to optics. Also, his work in optics is rivalled by equally significant work by his contemporaries, especially Huygens. Yet his creativity is apparent, even in ideas and models in optics that were later abandoned in science. His main areas of interest are theoretical physics and physics education. He has been involved in the science olympiad programme in India from its inception in 1998.  相似文献   
239.
INTRODUCTION Bangla language is characterized by a rich sys-tem of inflections(VIBHAKTI),derivation,and compound formation(Saha et al.,2004;Dash,1994;Chakroborty,2003),which is why the NLE using Bangla(output generation)is a very challenging task.Natural Language Engineering(NLE)is the process of computer analysis of input provided in a human language(natural language)and conversion of this input into a useful form of representation.The input of an NLP system can be:written text …  相似文献   
240.
INTRODUCTION Some structures fail geometrically before thestrength failure because of lack of stability and such afailure is known as instability failure or bucklingfailure. Determination of buckling load is importantin order to ensure the stability of a structure. If thestructure under consideration is subjected to a dy-namic load then this problem comes under the pur-view of dynamic stability problems. Examples areslender offshore structures subjected to periodic ex-citations and colum…  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