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   46227篇
  免费   533篇
  国内免费   1387篇
电工技术   911篇
技术理论   2篇
综合类   667篇
化学工业   4499篇
金属工艺   1693篇
机械仪表   2513篇
建筑科学   2947篇
矿业工程   1442篇
能源动力   288篇
轻工业   8429篇
水利工程   883篇
石油天然气   1322篇
武器工业   235篇
无线电   2850篇
一般工业技术   14815篇
冶金工业   949篇
原子能技术   452篇
自动化技术   3250篇
  2023年   167篇
  2022年   230篇
  2021年   262篇
  2020年   167篇
  2019年   193篇
  2018年   227篇
  2017年   106篇
  2016年   148篇
  2015年   197篇
  2014年   434篇
  2013年   328篇
  2012年   4456篇
  2011年   5662篇
  2010年   1352篇
  2009年   735篇
  2008年   3584篇
  2007年   3471篇
  2006年   2896篇
  2005年   2504篇
  2004年   2221篇
  2003年   1946篇
  2002年   1838篇
  2001年   1509篇
  2000年   1443篇
  1999年   1056篇
  1998年   673篇
  1997年   773篇
  1996年   706篇
  1995年   646篇
  1994年   596篇
  1993年   422篇
  1992年   497篇
  1991年   563篇
  1990年   521篇
  1989年   547篇
  1988年   411篇
  1987年   476篇
  1986年   456篇
  1985年   521篇
  1984年   490篇
  1983年   443篇
  1982年   430篇
  1981年   368篇
  1980年   298篇
  1979年   235篇
  1978年   133篇
  1977年   70篇
  1975年   84篇
  1974年   84篇
  1965年   92篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
121.
Paul  G Weber  J 《特殊钢》1998,19(1):24-28
德国巴登钢铁公司(BSW)炼钢厂有2座80t电炉,2座钢包炉和2台5流连铸机,由于BSW的生产和管理人员具有高的素质,精心保养设备,保持高生产率,从而降低生产成本。去年BSW炼钢厂生产140多万t质量合格钢坯。全员劳动生产率超过2000t钢/人·年。  相似文献   
122.
利用地震数据估算速度时常常是以与方向性无关的时距曲线为基础的。尽管我们已经了解到许多岩石存在较强的各向异性,但多年来人们已根据各向同性估值得到了一些有益的结果。如果速度明显随方向变化,则各向同性假设将导致严重的构造解释误差。除此之外,与角度有关的信息将有助于更好地解释所测量的岩性。为了估算出每一波型的两个速度参数,VSP和井间数据的孔径是不够的。如果数据有一个对称的同相轴,我们可选择直达波速度(根据沿轴向的  相似文献   
123.
曾经一度是世界上最有活力的蓝色巨人IBM军团发现自己处境不妙:前进方向不明、处于竞争对手的包围之中,对手的力量超过了自己。西部战线是令人畏惧的Microsoft。这个一度曾与IBM结盟的Microsoft军团,装备精良,下定决心只做一件事——称霸。IBM军团的东面驻扎着Lotus军团,它虽然没有Microsoft军团那么咄咄逼人,但是目标明确,清楚地知道自己应该干什么。IBM军团的南面是不断进逼的  相似文献   
124.
采用最新的设计,移动式破碎机与胶带输送机相结合,可使地下开采费用显著节约。  相似文献   
125.
This article describes a commercial quartz tuning fork (QTF), 8 mm in height by 3 mm in diameter, holding a two-terminal electronic component with a nominal frequency of 32.768 kHz and 12.5 pF typical load capacitance packed in a vacuum-sealed metal container, which has been used as a sensor for low-temperature measurement with good sensitivity, repeatability, and reliability. An embedded readout design with the support of a programmable system on-chip (PSoC) and virtual instrument control program, which uses a personal computer as an input/output device, provides online data acquisition of the QTF frequency data, which will in turn provide the measurement of the low-temperature bath in which the QTF is immersed. The embedded PSoC readout captures the varying frequency signals from the QTF as a response to the measurement temperature, processes it, and sends the frequency value to a personal computer, where LabVIEW, a graphical language ("G" language), displays the data in a graphical format. The QTFs for low temperature (300 K to 77 K) are well studied, whereas a sensor using a PSoC embedded design as a readout is a novel design implementation.  相似文献   
126.
127.
General expressions for the values of the components of an electric equivalent circuit are derived for flexural vibrations. These expressions are applied to some interesting electrode configurations. The obtained values are in good agreement with experimental values and values specified by manufacturers of watch crystals. It is noted that solving Laplace's equation for the dielectric field is sufficient in order to obtain the values of the vibration amplitude, the piezoelectric current, and the equivalent components. The piezoelectric part of the electric field need only be considered if very accurate values of the resonance frequencies are desired. It is shown how accurate estimates can be obtained without the need of advanced calculation tools.  相似文献   
128.
Creating high-quality quad meshes from triangulated surfaces is a highly nontrivial task that necessitates consideration of various application specific metrics of quality. In our work, we follow the premise that automatic reconstruction techniques may not generate outputs meeting all the subjective quality expectations of the user. Instead, we put the user at the center of the process by providing a flexible, interactive approach to quadrangulation design. By combining scalar field topology and combinatorial connectivity techniques, we present a new framework, following a coarse to fine design philosophy, which allows for explicit control of the subjective quality criteria on the output quad mesh, at interactive rates. Our quadrangulation framework uses the new notion of Reeb atlas editing, to define with a small amount of interactions a coarse quadrangulation of the model, capturing the main features of the shape, with user prescribed extraordinary vertices and alignment. Fine grain tuning is easily achieved with the notion of connectivity texturing, which allows for additional extraordinary vertices specification and explicit feature alignment, to capture the high-frequency geometries. Experiments demonstrate the interactivity and flexibility of our approach, as well as its ability to generate quad meshes of arbitrary resolution with high-quality statistics, while meeting the user’s own subjective requirements.  相似文献   
129.
We present a process to automatically generate three-dimensional mesh representations of the complex, arborized cell membrane surface of cortical neurons (the principal information processing cells of the brain) from nonuniform morphological measurements. Starting from manually sampled morphological points (3D points and diameters) from neurons in a brain slice preparation, we construct a polygonal mesh representation that realistically represents the continuous membrane surface, closely matching the original experimental data. A mapping between the original morphological points and the newly generated mesh enables simulations of electrophysiolgical activity to be visualized on this new membrane representation. We compare the new mesh representation with the state of the art and present a series of use cases and applications of this technique to visualize simulations of single neurons and networks of multiple neurons.  相似文献   
130.
The rapid growth of motion capture data increases the importance of motion retrieval. The majority of the existing motion retrieval approaches are based on a labor-intensive step in which the user browses and selects a desired query motion clip from the large motion clip database. In this work, a novel sketching interface for defining the query is presented. This simple approach allows users to define the required motion by sketching several motion strokes over a drawn character, which requires less effort and extends the users’ expressiveness. To support the real-time interface, a specialized encoding of the motions and the hand-drawn query is required. Here, we introduce a novel hierarchical encoding scheme based on a set of orthonormal spherical harmonic (SH) basis functions, which provides a compact representation, and avoids the CPU/processing intensive stage of temporal alignment used by previous solutions. Experimental results show that the proposed approach can well retrieve the motions, and is capable of retrieve logically and numerically similar motions, which is superior to previous approaches. The user study shows that the proposed system can be a useful tool to input motion query if the users are familiar with it. Finally, an application of generating a 3D animation from a hand-drawn comics strip is demonstrated.  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