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   6401篇
  免费   738篇
  国内免费   570篇
电工技术   219篇
综合类   525篇
化学工业   606篇
金属工艺   81篇
机械仪表   683篇
建筑科学   110篇
矿业工程   74篇
能源动力   36篇
轻工业   199篇
水利工程   73篇
石油天然气   769篇
武器工业   74篇
无线电   1641篇
一般工业技术   529篇
冶金工业   221篇
原子能技术   358篇
自动化技术   1511篇
  2024年   28篇
  2023年   67篇
  2022年   143篇
  2021年   178篇
  2020年   201篇
  2019年   166篇
  2018年   192篇
  2017年   200篇
  2016年   283篇
  2015年   269篇
  2014年   321篇
  2013年   361篇
  2012年   387篇
  2011年   480篇
  2010年   348篇
  2009年   369篇
  2008年   363篇
  2007年   402篇
  2006年   392篇
  2005年   336篇
  2004年   307篇
  2003年   268篇
  2002年   230篇
  2001年   197篇
  2000年   192篇
  1999年   180篇
  1998年   129篇
  1997年   109篇
  1996年   109篇
  1995年   82篇
  1994年   68篇
  1993年   57篇
  1992年   49篇
  1991年   31篇
  1990年   43篇
  1989年   19篇
  1988年   22篇
  1987年   20篇
  1986年   24篇
  1985年   18篇
  1984年   22篇
  1983年   14篇
  1982年   6篇
  1981年   7篇
  1980年   4篇
  1979年   2篇
  1975年   2篇
  1973年   3篇
  1962年   2篇
  1955年   1篇
排序方式: 共有7709条查询结果,搜索用时 15 毫秒
181.
Abstract— The spatio‐temporal aperture and sample rate of a video display determines both the static and dynamic resolution of the video signal that is rendered. The dynamic display characteristics like the visibility of large‐area flicker, motion judder, and motion blur can be derived from the frame rate and the temporal extent of the pixel aperture (i.e., the temporal aperture). For example, liquid‐crystal displays (LCDs) have an aperture that is relatively small in the spatial dimension and wide in the temporal domain. Consequently, moving objects displayed on an LCD suffer from motion blur. Especially in TV applications, the temporal dimension has a large impact on the overall picture quality. The temporal aperture, together with the frame rate, is shown to predict the amount of perceived large‐area flicker, motion judder, and motion blur and also the performance of motion‐blur reduction algorithms for LCDs. From this analysis it is further determined how to obtain the optimal temporal aperture of a television display, for which not only properties of the human visual system (HVS), but also the properties of the video signal have to be taken into account.  相似文献   
182.
A JEOL JEM-3000F field emission, analytical, high-resolution transmission electron microscope (HRTEM) was used to study InN films grown on sapphire substrates. It was found that, while the InN films maintained the hexagonal (wurtzite) structure, InN nanodomains with a cubic (zincblende) structure were also formed in the films. Nanobeam electron diffraction techniques were applied for identification of the cubic phase. The identification of the cubic InN was confirmed by HRTEM structural imaging. The cubic InN nanodomains are 3-10 nm in diameter, and are orientated in two different orientations with their [110](cubic) and [110](cubic) axes parallel to each other and their (111)(cubic) planes parallel to the (0001)(hex) plane of the hexagonal InN.  相似文献   
183.
Full instrumental rationality and perfect institutions are two cornerstoneassumptions underlying neoclassical models. However, in the real world, thesetwo assumptions never hold, especially not in developing countries. In thispaper, we develop a game theoretical model to investigate if relaxations inthe full instrumental rationality and perfect institutions premise can explainthe conflicts that have been occurring between the various principals in theNarok district in Kenya with regard to land tenure and use.  相似文献   
184.
非均匀抽样网格简化   总被引:2,自引:0,他引:2  
提出了一种考虑视点空间中某些重要视点的非均匀抽样网格简化的新方法,是在借鉴了Garland-Heckbert方法的基础上提出的,是一种考虑外观相似性的简化算法。给出并证明了两个判定边界的定理,为抽样提供了理论依据。在简化过程中,该算法通过采用视点空间中某些重要视点对模型进行抽样,使抽中的顶点对(轮廓附近的顶点对)得到适当保护。该算法除具有Garland-Heckbert方法的长处外,还可以在三角面片数较少的情况下(50多个三角面片),尽可能保持模型的重要外观特征,给出了计算0-1图像的外观相似性误差的公式,通过该公式对简化结果进行比较,证明提出的简化算法对保持模型的外观特征是行之有效的。最后对该算法的时间和空间复杂性进行了分析。  相似文献   
185.
熊光楞  马海波 《控制与决策》2001,16(Z1):721-724
针对并行设计中冲突协商策略的选取和优化解的非唯一性问题,给出了冲突的数学描述形式以及冲突原因的数学解释,证明了合作策略的优越性,研究了基于Nash定理的冲突协商解的存在性和唯一性,并给出一种协商模型以及具体应用实例.  相似文献   
186.
介绍高速IP路由器体系结构下分布式ARP的实现方法,主要阐述了ARP主从分布式控制方法和分布式ARP软件设计思想。  相似文献   
187.
胡涛  王永刚  薛延学 《计算机应用》2001,21(12):15-16,19
为了在物理网络上建立两台主机的通信,必须要进行地址解析。文中介绍了地址解析技术的机制及实现方法,并比较了因特网上常用的三种地址解析算法的优缺点,给出了相应的应用范围。  相似文献   
188.
由于非压缩视频序列具有明显的直观性视觉特征,并在实际应用中仍占据相当大的比重,针对在非压缩视频的处理中仍然存在对镜头变化的类型、镜头渐变和突变的位置分析不够准确的难点,提出了一种时域分辨率的非压缩域视频分割算法,在提取序列的基于强边缘块的直方图,比较不同序列之间的差异的基础上,采用多分辨率的算法进行镜头检测。实验证明,这种方法实现了自动视频分割并较好地克服了上述的缺点。  相似文献   
189.
This paper studies the problem of detecting multiplechanges at unknown times in the mean level of elision in thetrimeter sequences of the Orestes, a play written by theAncient Greek dramatist Euripides (485–406 B.C.). Change-detection statistics proposed by MacNeill (1978) and Jandhayala and MacNeill(1991) are adopted for this purpose. Analysis of the trimetersequences yields several points of change. A general explanation fortheir occurrence appears to be that Euripides varies his use ofelision according to the emotional content of his text, i.e., heseems to change the form to support the content and, thus, seems touse elision frequency as a dramatic instrument.  相似文献   
190.
Resolution theory offers a simple, complete method for proving theorems but is generally considered impractical. The theorems we are interested in proving arise in the analysis of programs and usually involve quantification. We have developed a system for proving these theorems using resolution, but have embedded in it a simplifier as the central component. The simplifier is an integrated collection of algorithms for normalizing arithmetic, relational, and logical expressions. The knowledge in the simplifier is encoded in procedures, rather than as axioms or rules. We use the simplifier to prove certain theorems, reduce the clutter in theorems, and reduce the cost of unification, Inherent in the normal form algorithms is the notion of strengthening (e.g., inferringa =b froma b ANDb a). We have incorporated the notion into the unification algorithm as well. The design of the system permits its use along a spectrum from pure resolution to resolution with interpretation of the arithmetic and relational operators. Strengthening is a heuristic that permits the movement along this spectrum. We call the approachi-resolution.i-resolution does not preserve completeness; it does define a means for approaching completeness efficiently and systematically. It thus attempts to provide a pragmatic approach to mechanical theorem proving.  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