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   3734篇
  免费   15篇
  国内免费   1篇
教育   2389篇
科学研究   916篇
各国文化   8篇
体育   88篇
综合类   7篇
文化理论   65篇
信息传播   277篇
  2023年   4篇
  2022年   16篇
  2021年   46篇
  2020年   12篇
  2019年   24篇
  2018年   101篇
  2017年   134篇
  2016年   205篇
  2015年   156篇
  2014年   92篇
  2013年   160篇
  2012年   184篇
  2011年   196篇
  2010年   116篇
  2009年   75篇
  2008年   105篇
  2007年   89篇
  2006年   90篇
  2005年   712篇
  2004年   489篇
  2003年   324篇
  2002年   145篇
  2001年   77篇
  2000年   44篇
  1999年   34篇
  1998年   17篇
  1997年   16篇
  1996年   8篇
  1995年   12篇
  1994年   11篇
  1993年   7篇
  1992年   8篇
  1991年   5篇
  1990年   3篇
  1989年   7篇
  1988年   2篇
  1987年   5篇
  1986年   3篇
  1985年   2篇
  1984年   1篇
  1983年   2篇
  1980年   1篇
  1979年   1篇
  1977年   1篇
  1976年   4篇
  1975年   1篇
  1973年   2篇
  1962年   1篇
排序方式: 共有3750条查询结果,搜索用时 515 毫秒
71.
72.
反应级数的确定在化学动力学研究中非常重要,现给出了利用计算机和用微分法确定反应级数的方法.为了使编程的程序简短、高效,采用MATLAB语言作为编程语言.  相似文献   
73.
74.
Luciferase from firefly lantern extract was immobilized on CNBr-activated Sepharose 4B. The kinetic properties of immobilized luciferase were extensively studied. TheK m′ for D-luciferin is 11.9 μmol/L, the optimum pH and temperature for Sepharose-bound enzyme were 7.8 and 25°C respectively. A luminescence fiber optic biosensor, making use of immobilized crude luciferase, was developed for assay of ATP. The peak light intensity was linear with respect to ATP concentration in range of 10−9–10−5 mol/L. A biological application was also demonstrated with the determination of serum ATP from rats bred in low versus normal oxygen environments.  相似文献   
75.
Analysis of self-reflections of undergraduate education students in a project involving web-supported counterintuitive science demonstrations is reported in this paper. Participating students (N?=?19) taught science with counterintuitive demonstrations in local elementary school classrooms and used web-based resources accessed via wireless USB adapters. Student reflections to seven questions were analyzed qualitatively using four components of reflection (meeting objectives/perception of learning, dynamics of pedagogy, special needs accommodations, improving teaching) deriving 27 initial data categories and 12 emergent themes. Overall the undergraduates reported meeting objectives, engaging students in pedagogically relevant learning tasks including, providing accommodations to students with special needs, and gaining practice and insight to improve their own teaching. Additional research is needed to arrive at generalizable findings concerning teaching with web-supported counterintuitive science demonstrations in elementary classrooms.  相似文献   
76.
77.
In 2001, for the first time in the history of the International Association for Counselling, International Conference was held in a developing Asian country–India, with the theme Families in Transition–Counselling in Transition–Meeting the Challenges Ahead. This special issue contains some of the presentations made by Indian participants during this conference which best reflect the challenges and diversities of counseling efforts with families in India. The first article was specially written for this issue in order to give an international relationship of this journal an in depth contextual understanding of Indian families in transition and the challenges they pose to the contemporary Indian counselor. Two articles are reflected to counseling families affected by socio-politial and economic changes. Five authors have written on counseling related to physical and mental disability/addiction and last two articles are reflected to authors experiences as family counselors.  相似文献   
78.
Kinetic knowledge is of great importance in achieving good control of the pyrolysis and gasification process and optimising system design. An overall kinetic pyrolysis scheme is therefore addressed here. The kinetic modelling incorporates the following basic steps: the degradation of the virgin biomass materials into primary products (tar, gas and semi-char), the decomposition of primary tar into secondary products and the continuous interaction between primary gas and char. The last step is disregarded completely by models in the literature. Analysis and comparison of predicted results from different kinetic schemes and experimental data on our fixed bed pyrolyser yielded very positive evidence to support our kinetic scheme. Project (No. 2001CB409600) Supported by the National Key Basic Research Program (973) of China  相似文献   
79.
普通话二字组词语不同的声调组合方式 ,使前后位声调产生不同的动态变化形式。前位声调的动态变化明显表现在上声调变为低降调和中升调上 ;后位声调的动态变化则表现在调值的明显改变上。后位声调的动态变化更为普遍 ,应该引起足够的重视  相似文献   
80.
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