全文获取类型
收费全文 | 4242篇 |
免费 | 276篇 |
国内免费 | 13篇 |
专业分类
电工技术 | 49篇 |
化学工业 | 1280篇 |
金属工艺 | 87篇 |
机械仪表 | 138篇 |
建筑科学 | 141篇 |
矿业工程 | 24篇 |
能源动力 | 137篇 |
轻工业 | 545篇 |
水利工程 | 33篇 |
石油天然气 | 30篇 |
武器工业 | 1篇 |
无线电 | 291篇 |
一般工业技术 | 749篇 |
冶金工业 | 310篇 |
原子能技术 | 45篇 |
自动化技术 | 671篇 |
出版年
2024年 | 10篇 |
2023年 | 56篇 |
2022年 | 176篇 |
2021年 | 217篇 |
2020年 | 142篇 |
2019年 | 149篇 |
2018年 | 184篇 |
2017年 | 166篇 |
2016年 | 175篇 |
2015年 | 143篇 |
2014年 | 199篇 |
2013年 | 347篇 |
2012年 | 252篇 |
2011年 | 308篇 |
2010年 | 211篇 |
2009年 | 203篇 |
2008年 | 192篇 |
2007年 | 163篇 |
2006年 | 139篇 |
2005年 | 123篇 |
2004年 | 86篇 |
2003年 | 70篇 |
2002年 | 68篇 |
2001年 | 49篇 |
2000年 | 41篇 |
1999年 | 46篇 |
1998年 | 86篇 |
1997年 | 57篇 |
1996年 | 43篇 |
1995年 | 40篇 |
1994年 | 35篇 |
1993年 | 37篇 |
1992年 | 20篇 |
1991年 | 18篇 |
1990年 | 15篇 |
1989年 | 18篇 |
1988年 | 16篇 |
1987年 | 28篇 |
1986年 | 16篇 |
1985年 | 16篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 16篇 |
1981年 | 9篇 |
1979年 | 14篇 |
1978年 | 10篇 |
1976年 | 14篇 |
1975年 | 9篇 |
1973年 | 14篇 |
1972年 | 8篇 |
排序方式: 共有4531条查询结果,搜索用时 15 毫秒
271.
Daniel Aguiar da Silva Patrícia D.L. Machado 《Electronic Notes in Theoretical Computer Science》2006,164(4):29-40
This paper presents an approach for the generation of test purposes in the form of labelled transition systems from specifications of properties in CTL. The approach is aimed at adapting the model checking process, by extending search algorithms to perform further analysis so that examples and counter-examples can be extracted. An algorithm for the generation of test purposes through analysis over the examples and counter-examples is presented, along with a case study to show the correspondence between the CTL properties and the generated test purposes. 相似文献
272.
State estimation problems for linear time-invariant systems with noisy inputs and outputs are considered. An efficient recursive algorithm for the smoothing problem is presented. The equivalence between the optimal filter and an appropriately modified Kalman filter is established. The optimal estimate of the input signal is derived from the optimal state estimate. The result shows that the noisy input/output filtering problem is not fundamentally different from the classical Kalman filtering problem. 相似文献
273.
E. A. S. Galvanin G. M. do Vale A. P. Dal Poz 《Pattern Recognition and Image Analysis》2006,16(4):614-621
This paper proposes a methodology for edge detection in digital images using the Canny detector, but associated with a priori edge structure focusing by a nonlinear anisotropic diffusion via the partial differential equation (PDE). This strategy aims at minimizing the effect of the well-known duality of the Canny detector, under which is not possible to simultaneously enhance the insensitivity to image noise and the localization precision of detected edges. The process of anisotropic diffusion via thePDE is used to a priori focus the edge structure due to its notable characteristic in selectively smoothing the image, leaving the homogeneous regions strongly smoothed and mainly preserving the physical edges, i.e., those that are actually related to objects presented in the image. The solution for the mentioned duality consists in applying the Canny detector to a fine gaussian scale but only along the edge regions focused by the process of anisotropic diffusion via the PDE. The results have shown that the method is appropriate for applications involving automatic feature extraction, since it allowed the high-precision localization of thinned edges, which are usually related to objects present in the image. 相似文献
274.
PETRI 网在软件过程建模及过程实施中的应用 总被引:2,自引:1,他引:2
软件过程技术,作为一种保证软件开发质量和效率的方法,在许多软件企业引起了重视和应用。本文从条件/事件网出发,应用标记PETRI网,并针对其在软件过程中的特点,给出了软件过程和软件过程网合理性的定义,根据工作流领域的结论,可以应用经典PETRI网的工具验证其合理性。在此理论基础上,提出了传统的软件过程结构表示成软件过程网的规则。并研究其在实践中的应用,最后用一个实际软件开发企业中的应用实例详细解释了所提出的理论及应用。 相似文献
275.
The H2-norm control problem of discrete-time Markov jump linear systems is addressed in this paper when part of, or the total of the Markov states is not accessible to the controller. The non-observed part of the Markov states is grouped in a number of clusters of observations; the case with a single cluster retrieves the situation when no Markov state is observed. The control action is provided in linear feedback form, which is invariant on each cluster, and this restricted complexity setting is adopted, aiming at computable solutions. We explore a recent result by de Oliveira, Bernussou, and Geromel (Systems Control Lett. 37 (1999) 261) involving an LMI characterization to establish a H2 solution that is stabilizing in the mean square sense. The novelty of the method is that it can handle in LMI form the situation ranging from no Markov state observation to complete state observation. In addition, when the state observation is complete, the optimal H2-norm solution is retrieved. 相似文献
276.
This paper focuses on BSR (Broadcasting with Selective Reduction) implementation of algorithms solving basic convex polygon problems. More precisely, constant time solutions on a linear number, max(N, M) (where N and M are the number of edges of the two considered polygons), of processors for computing the maximum distance between two convex polygons, finding critical support lines of two convex polygons, computing the diameter, the width of a convex polygon and the vector sum of two convex polygons are described. These solutions are based on the merging slopes technique using one criterion BSR operations. 相似文献
277.
A Guimar?es A Machado S Carvalho H Alaiz L Vieira M Abecasis 《Canadian Metallurgical Quarterly》1998,22(6):595-597
The authors calculated the shunt revision rate for 77 consecutive patients with tumoural obstructive hydrocephalus. At a mean follow up of 23.7 months, the annual revision rate was 0.06 which is significantly lower than the annual revision rate of 0.39 for other hydrocephalic patients treated during the same period. Shunted patients who had total excision of their lesions had a significantly lower revision rate than patients who had a partial excision or a biopsy. It is therefore, suggested that cases with tumoural obstructive hydrocephalus may represent a subset of hydrocephalic patients who are associated with a relatively low risk of shunt complications. The observation has to be addressed when the role of endoscopic third ventriculostomy in these patients is being considered. 相似文献
278.
The radiosity method is particularly suitable for global illumination calculations in static environments. Nonetheless, recent applications of image synthesis such as architectural simulation or lighting design require the ability to modify environments. Previous methods have attempted to deal with dynamic environments (environments where the geometry, the material properties, etc., can change)but still suffer some limitations in the case of moving objects. One of the main problems remaining is the efficient and accurate detection of which form factors must really be recomputed, since their calculation is the most time-consuming part of the radiosity method. To correctly understand and solve this problem, we start with a method in 2D for polygonal scenes using the visibility complex. It is a powerful data structure representing the visibility relationships between objects in the plane. We have developed and implemented an algorithm which uses this structure to efficiently compute the discontinuity mesh and the form factors for static scenes. We also propose an extension to our algorithm to efficiently update only the modified form factors when an object is moving. This approach enhances our understanding and will hopefully lead to efficient solutions in 3D. 相似文献
279.
280.
V-Effects of thrombolytic therapy on coronary reperfusion and left ventricular function VI-Noninvasive markers of reperfusion. VII-Timing of thrombolysis. VIII-Side effects and adverse outcomes. 相似文献