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   15569篇
  免费   826篇
  国内免费   28篇
电工技术   166篇
综合类   43篇
化学工业   3342篇
金属工艺   307篇
机械仪表   315篇
建筑科学   685篇
矿业工程   45篇
能源动力   503篇
轻工业   1228篇
水利工程   124篇
石油天然气   51篇
无线电   1119篇
一般工业技术   2962篇
冶金工业   2260篇
原子能技术   117篇
自动化技术   3156篇
  2023年   165篇
  2022年   359篇
  2021年   573篇
  2020年   374篇
  2019年   380篇
  2018年   496篇
  2017年   461篇
  2016年   532篇
  2015年   465篇
  2014年   594篇
  2013年   1060篇
  2012年   971篇
  2011年   1155篇
  2010年   807篇
  2009年   749篇
  2008年   788篇
  2007年   774篇
  2006年   582篇
  2005年   505篇
  2004年   371篇
  2003年   381篇
  2002年   338篇
  2001年   214篇
  2000年   186篇
  1999年   205篇
  1998年   211篇
  1997年   187篇
  1996年   188篇
  1995年   182篇
  1994年   154篇
  1993年   149篇
  1992年   123篇
  1991年   79篇
  1990年   124篇
  1989年   118篇
  1988年   85篇
  1987年   93篇
  1986年   101篇
  1985年   101篇
  1984年   90篇
  1983年   77篇
  1982年   96篇
  1981年   90篇
  1980年   73篇
  1979年   70篇
  1978年   66篇
  1977年   74篇
  1976年   62篇
  1975年   47篇
  1974年   43篇
排序方式: 共有10000条查询结果,搜索用时 10 毫秒
51.
We present four studies investigating tools and methodologies for artist-scientist-technologist collaboration in designing multivariate, virtual reality (VR) visualizations. Design study 1 identifies the promise of 3D drawing-style interfaces for VR design and also establishes limitations of these tools with respect to precision and support for animation. Design study 2 explores animating artist-created visualization designs with scientific 3D fluid flow data. While results captured an accurate sense of flow that was advantageous as compared to the results of study 1, the potential for visual exploration using the design tools tested was limited. Design study 3 reveals the importance of a new 3D interface that overcomes the precision limitation found in study 1 while remaining accessible to artist collaborators. Drawing upon previous results, design study 4 engages collaborative teams in a design process that begins with traditional paper sketching and moves to animated, interactive, VR prototypes "sketched" by designers in VR using interactive 3D tools. Conclusions from these four studies identify important characteristics of effective artist-accessible VR visualization design tools and lead to a proposed formalized methodology for successful collaborative design that we expect to be useful in guiding future collaborations. We call this proposed methodology Scientific Sketching.  相似文献   
52.
What is the impact of business process standardization on business process outsourcing (BPO) success? This paper argues that there is a direct impact of process standardization on BPO success, due to production cost economies, and also an indirect effect via improved contractual and relational governance resulting from better monitoring opportunities and facilitated communication and coordination. This threefold impact of standardization on BPO success is empirically confirmed using data from 335 BPO ventures in 215 German banks.  相似文献   
53.
Deformation models for image recognition   总被引:2,自引:0,他引:2  
We present the application of different nonlinear image deformation models to the task of image recognition. The deformation models are especially suited for local changes as they often occur in the presence of image object variability. We show that, among the discussed models, there is one approach that combines simplicity of implementation, low-computational complexity, and highly competitive performance across various real-world image recognition tasks. We show experimentally that the model performs very well for four different handwritten digit recognition tasks and for the classification of medical images, thus showing high generalization capacity. In particular, an error rate of 0.54 percent on the MNIST benchmark is achieved, as well as the lowest reported error rate, specifically 12.6 percent, in the 2005 international ImageCLEF evaluation of medical image specifically categorization.  相似文献   
54.
From Non-Functional Requirements to Design through Patterns   总被引:8,自引:2,他引:6  
  相似文献   
55.
56.
The H almost disturbance decoupling problem is considered. In this paper, a nonlinear design is proposed to find a state feedback controller for bilinear systems. The closed‐loop system is internally stable and achieves disturbance attenuation in nonlinear H sense. We defined a special form of Lyapunov function, which is constructed in terms of one or a set of positive definite constant matrices. If, except of the origin of system, the corresponding polynomial of the positive definite matrix (or several polynomials relevant to the positive definite constant matrices) has (have) no zero on a given subset of state space, then we can construct a controller to solve our problem. It is found that the controller structure could be complicated, but is feasible in computation and may require optimization technique to search the solution. We consider both SIMO and MIMO cases with illustrated examples.  相似文献   
57.
The second-sound velocity of a superfluid mixture increases when a static and homogeneous magnetic field is applied. In particular, for dilute mixtures (molar 3 He concentration <0.1) and low temperatures, (0.1<T<0.6 K) the relative velocity increase is independent of concentration and is given by u 2/u 25×1016 B e 2 T –2. It should be easily observed wheneverB e T –1is larger than 10 5 G K1 and can lead to a novel measurement of the magnetic susceptibility.  相似文献   
58.
Summary In this paper, we consider the following problem: given a layered network including a set of messages, each of which must be transmitted from a source to a sink node, what is the sequence of moves from one node to another which minimizes the total completion time? We first show that the general problem is NP-complete for both fixed and variable path routing (thus the scheduling problem for more realistic networks with cycles must be considered computationally intractable). We then consider several restrictions which admit polynomia time algorithms.Most of this work was done while this author was at the Department of Mathematics, University of Rome La Sapienza  相似文献   
59.
Here we describe a novel, hand-held reference point indentation (RPI), instrument that is designed for clinical measurements of bone material properties in living patients. This instrument differs from previous RPI instruments in that it requires neither a reference probe nor removal of the periosteum that covers the bone, thus significantly simplifying its use in patient testing. After describing the instrument, we discuss five guidelines for optimal and reproducible results. These are: (1) the angle between the normal to the surface and the axis of the instrument should be less than 10°, (2) the compression of the main spring to trigger the device must be performed slowly (>1 s), (3) the probe tip should be sharper than 10 μm; however, a normalized parameter with a calibration phantom can correct for dull tips up to a 100 μm radius, (4) the ambient room temperature should be between 4?°C and 37 °C, and (5) the effective mass of the bone or material under test must exceed 1 kg, or if under 1 kg, the specimen should be securely anchored in a fixation device with sufficient mass (which is not a requirement of previous RPI instruments). Our experience is that a person can be trained with these guidelines in about 5 min and thereafter obtain accurate and reproducible results. The portability, ease of use, and minimal training make this instrument suitable to measure bone material properties in a clinical setting.  相似文献   
60.
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