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   662篇
  免费   12篇
  国内免费   2篇
化学   493篇
晶体学   11篇
力学   10篇
数学   90篇
物理学   72篇
  2023年   4篇
  2022年   4篇
  2021年   6篇
  2020年   12篇
  2019年   5篇
  2018年   12篇
  2017年   9篇
  2016年   12篇
  2015年   9篇
  2014年   10篇
  2013年   36篇
  2012年   41篇
  2011年   43篇
  2010年   25篇
  2009年   21篇
  2008年   32篇
  2007年   46篇
  2006年   43篇
  2005年   31篇
  2004年   36篇
  2003年   35篇
  2002年   31篇
  2001年   8篇
  2000年   10篇
  1999年   4篇
  1998年   9篇
  1997年   7篇
  1996年   15篇
  1995年   3篇
  1994年   3篇
  1993年   9篇
  1992年   11篇
  1991年   4篇
  1990年   6篇
  1989年   12篇
  1988年   8篇
  1987年   7篇
  1986年   3篇
  1985年   5篇
  1984年   5篇
  1980年   5篇
  1979年   4篇
  1978年   2篇
  1977年   3篇
  1976年   5篇
  1975年   4篇
  1974年   4篇
  1973年   4篇
  1971年   3篇
  1967年   2篇
排序方式: 共有676条查询结果,搜索用时 421 毫秒
191.
192.
193.
This study evaluated the effectiveness of teacher‐scientist partnerships for increasing the use. of inquiry in precollege classrooms. It assessed the influence of the Teaching About Energy Through Inquiry Institutes for middle and high school teachers and energy scientists on participants' attitudes about science and science education, use of inquiry instructional techniques, and student attitudes about their classroom environments. Participant surveys, institute and classroom observations, lesson plans, and interviews indicated increased appreciation for inquiry, greater confidence in teaching using inquiry, and greater use of inquiry in the classroom. Student surveys and classroom observations pointed to higher levels of student satisfaction and less friction among classmates during inquiry‐based investigations implemented after the institutes. Moreover, scientist partners reported increased familiarity with principles of science education and best teaching practice, which are essential skills and knowledge for disseminating results of scientific research to nonscientific audiences, as well as their own students. These results suggest that collaborations between teachers and research scientists can positively affect the environment for learning science in precollege and college classes. Successful collaborations are most likely to occur when equal status for teachers and scientists in the partnership is stressed and partners have the opportunity to explore inquiry‐based curricula together.  相似文献   
194.
The wings of some insects, such as cicadae, have been reported to possess a number of interesting and unusual qualities such as superhydrophobicity, anisotropic wetting and antibacterial properties. Here, the chemical composition of the wings of the Clanger cicada (Psaltoda claripennis) were characterized using infrared (IR) microspectroscopy. In addition, the data generated from two separate synchrotron IR facilities, the Australian Synchrotron Infrared Microspectroscopy beamline (AS‐IRM) and the Synchrotron Radiation Center (SRC), University of Wisconsin‐Madison, IRENI beamline, were analysed and compared. Characteristic peaks in the IR spectra of the wings were assigned primarily to aliphatic hydrocarbon and amide functionalities, which were considered to be an indication of the presence of waxy and proteinaceous components, respectively, in good agreement with the literature. Chemical distribution maps showed that, while the protein component was homogeneously distributed, a significant degree of heterogeneity was observed in the distribution of the waxy component, which may contribute to the self‐cleaning and aerodynamic properties of the cicada wing. When comparing the data generated from the two beamlines, it was determined that the SRC IRENI beamline was capable of producing higher‐spatial‐resolution distribution images in a shorter time than was achievable at the AS‐IRM beamline, but that spectral noise levels per pixel were considerably lower on the AS‐IRM beamline, resulting in more favourable data where the detection of weak absorbances is required. The data generated by the two complementary synchrotron IR methods on the chemical composition of cicada wings will be immensely useful in understanding their unusual properties with a view to reproducing their characteristics in, for example, industry applications.  相似文献   
195.
This comparative study aims to identify the philosophical underpinnings of the principles of two approaches to the teaching of primary mathematics, the English Numeracy Strategy and the Dutch Realistic Mathematics Education and to discuss pedagogical implications. Philosophical views of knowledge as personal'subjective' and culturally'constructed' are considered in relation to inter subjectivity as a state of shared knowledge within a community of mathematicians. The didactics of the teaching of mental calculation strategies from the two approaches are used to illustrate a key epistemological difference in the mathematics that is presented to children.  相似文献   
196.
The review presents the recent trends in green and sustainable chemistry, as well as waste valorization and their applicability to understand and realize the concept of a circular economy. It also provides a comprehensive global perspective of the linear plastics economy and makes the case for its transformation into a circular plastics economy. Furthermore, bioconversion in a food waste biorefinery to produce fructose as an example of a high value-added product is given as a case study to demonstrate the feasibility of a circular economy.  相似文献   
197.
198.
199.
200.
Investigations of the impact regimes for a liquid droplet impacting onto horizontal moving liquid films are presented here for the first time. The aim of this study is to show the main impact outcomes and to highlight the effect the movement of films has upon these outcomes. The droplet diameters used in this experiment were 2.47 and 3.86 mm with impact Weber number of between 0.6 and 460. The Reynolds number of the moving film was between 351 and 1,818 depending on the flow rate (1–5.5 L/min) with changes in the film height of between 4.3 and 9.4 mm. The results showed that the impact outcomes exhibit the same regimes established for the impact on static liquids but with different transition boundaries. Moreover, the shape of the impact outcomes is unsymmetrical similar to the inclined impact on static liquids. The impact outcomes are shown to undergo a transition as the Reynolds number of the film increases, this occurs at a threshold value close to the expected transition between laminar and turbulent flow.  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