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   11507篇
  免费   1篇
教育   8899篇
科学研究   1208篇
体育   341篇
文化理论   384篇
信息传播   676篇
  2024年   1篇
  2021年   3篇
  2020年   1篇
  2019年   7篇
  2018年   2170篇
  2017年   2075篇
  2016年   1565篇
  2015年   105篇
  2014年   112篇
  2013年   68篇
  2012年   220篇
  2011年   691篇
  2010年   833篇
  2009年   429篇
  2008年   640篇
  2007年   1145篇
  2006年   68篇
  2005年   391篇
  2004年   444篇
  2003年   356篇
  2002年   127篇
  2001年   6篇
  2000年   19篇
  1999年   2篇
  1998年   1篇
  1997年   14篇
  1996年   1篇
  1992年   1篇
  1991年   6篇
  1990年   1篇
  1989年   1篇
  1987年   1篇
  1980年   2篇
  1976年   1篇
  1973年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
221.
    
Radiative imaging of combustion flame in furnace of power plant plays an increasingly important role in combustion diagnosis. This paper presents a new method for calculating the radiative imaging of three-dimensional (3D) combustion flame based on Monte Carlo method and optical lens imaging. Numerical simulation case was used in this study. Radiative images were calculated and images obtained can not only present the energy distribution on the charge-coupled device (CCD) camera target plane but also reflect the energy distribution condition in the simulation furnace. Finally the relationships between volume ele- ments and energy shares were also discussed.  相似文献   
222.
    
Particle pollution in air, also sometimes known as fine dust contamination, may cause electric contact failure. Recent research further proved that the fine particle is becoming a major disruption of the electronic connectors in signal transmission system. This paper specifies the connector contact in mobile phone application. To study the contact failure of mobile phone, a series of inspections and analytical research methods are introduced. Special features that cause the contact failure are summarized. Particle accumulation is the main problem; organic material such as lactates from sweat of the human body may act as adhesives to stick the separate particles together and make them adhere on the contact surface; chemical properties of dust cause serious local corrosion. The corrosion products may trap the particles and firmly attach on the contact surface; micro motion frequently occurs at the contact interface. Hard particle can be embedded into the surface, and soft particle could be squeezed and inserted into the contact; silicon compounds in dust play the most important role in forming high resistance regions that lead to failure; deposition of particles depends on the amount of materials, static electricity attracting force and gravity force applied on the particles. Current dust test can hardly reflect the serious contact failure. It is difficult to simulate the complexity of contact failure caused by particle contamination. Thus alternative ways of simulation experiment and improvement of contact reliability are proposed.  相似文献   
223.
    
Surabhi Potnis 《Resonance》2017,22(3):257-268
This article aims to highlight the amazing properties and potential uses of the more recently developed allotropes of carbon such as carbon nanotubes, graphene, fullerene, and buckypaper. This is an area offering wide opportunity for research, especially due to the multidisciplinary nature of applications.  相似文献   
224.
Problem solving is an important skill in the knowledge economy. Research indicates that the development of problem solving skills works better in the context of instructional approaches centered on real-world problems. But students need scaffolding to be successful in such instruction. In this paper I present a conceptual framework for understanding the effects of scaffolding. First, I discuss the ultimate goal of scaffolding—the transfer of responsibility—and one way that scholars have conceptualized promoting this outcome (fading). Next, I describe an alternative way to conceptualize transfer of responsibility through the lens of distributed cognition and discuss how this lens informs how to promote transfer of responsibility. Then I propose guidelines for the creation of problem solving scaffolds to support transfer of responsibility and discuss them in light of the literature.  相似文献   
225.
The identification and use of molecular biomarkers have greatly improved the diagnosis and treatment of malignant tumors. However, a much deeper understanding of oncogenic proteins is needed for the benefit to cancer patients. The lipid raft marker proteins, flotillin-1 and flotillin-2, were first found in goldfish retinal ganglion cells during axon regeneration. They have since been found in a variety of cells, mainly on the inner surface of cell membranes, and not only act as a skeleton to provide a platform for protein–protein interactions, but also are involved in signal transduction, nerve regeneration, endocytosis, and lymphocyte activation. Previous studies have shown that flotillins are closely associated with tumor development, invasion, and metastasis. In this article, we review the functions of flotillins in relevant cell processes, their underlying mechanisms of action in a variety of tumors, and their potential applications to tumor molecular diagnosis and targeted therapy.  相似文献   
226.
Luck (2009) argues that gamers face a dilemma when it comes to performing certain virtual acts. Most gamers regularly commit acts of virtual murder, and take these acts to be morally permissible. They are permissible because unlike real murder, no one is harmed in performing them; their only victims are computer-controlled characters, and such characters are not moral patients. What Luck points out is that this justification equally applies to virtual pedophelia, but gamers intuitively think that such acts are not morally permissible. The result is a dilemma: either gamers must reject the intuition that virtual pedophelic acts are impermissible and so accept partaking in such acts, or they must reject the intuition that virtual murder acts are permissible, and so abstain from many (if not most) extant games. While the prevailing solution to this dilemma has been to try and find a morally relevant feature to distinguish the two cases, I argue that a different route should be pursued. It is neither the case that all acts of virtual murder are morally permissible, nor are all acts of virtual pedophelia impermissible. Our intuitions falter and produce this dilemma because they are not sensitive to the different contexts in which games present virtual acts.  相似文献   
227.
Retractions serve as one perspective of the publishing process, and can offer vast insight into the problems associated with basic research, with the traditional publishing platform, or with policies. Some established retraction guidelines exist, such as those established by the Committee on Publication Ethics, or COPE. This essay provides a perspective of stealth or silent retractions within the broader concept of retractions, and within the framework of the COPE retraction guidelines. The issue of opaque retraction notices, especially in the case of COPE members, as well as the prominence of questionable retraction policies among select “predatory” open access publishers, is emphasized. Select clear examples are provided.  相似文献   
228.
This article discusses an empirical study on the use of history as a goal. A historical module is designed and implemented in a Danish upper secondary class in order to study the students’ capabilities at engaging in meta-issue discussions and reflections on mathematics and its history. Based on videos of the implementation, students’ hand-in essay assignments, questionnaires, and follow-up interviews, the conditions, sense, and extent to which the students are able to perform such discussions and reflections are analyzed using a described theoretical framework.  相似文献   
229.
230.
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