全文获取类型
收费全文 | 7853篇 |
免费 | 283篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 79篇 |
综合类 | 3篇 |
化学工业 | 1713篇 |
金属工艺 | 145篇 |
机械仪表 | 148篇 |
建筑科学 | 386篇 |
矿业工程 | 22篇 |
能源动力 | 225篇 |
轻工业 | 629篇 |
水利工程 | 58篇 |
石油天然气 | 45篇 |
武器工业 | 1篇 |
无线电 | 545篇 |
一般工业技术 | 1430篇 |
冶金工业 | 1379篇 |
原子能技术 | 30篇 |
自动化技术 | 1310篇 |
出版年
2023年 | 55篇 |
2022年 | 91篇 |
2021年 | 167篇 |
2020年 | 134篇 |
2019年 | 128篇 |
2018年 | 163篇 |
2017年 | 129篇 |
2016年 | 206篇 |
2015年 | 143篇 |
2014年 | 231篇 |
2013年 | 502篇 |
2012年 | 383篇 |
2011年 | 476篇 |
2010年 | 351篇 |
2009年 | 296篇 |
2008年 | 398篇 |
2007年 | 362篇 |
2006年 | 294篇 |
2005年 | 286篇 |
2004年 | 231篇 |
2003年 | 196篇 |
2002年 | 202篇 |
2001年 | 135篇 |
2000年 | 127篇 |
1999年 | 121篇 |
1998年 | 174篇 |
1997年 | 159篇 |
1996年 | 122篇 |
1995年 | 123篇 |
1994年 | 93篇 |
1993年 | 107篇 |
1992年 | 108篇 |
1991年 | 68篇 |
1990年 | 77篇 |
1989年 | 77篇 |
1988年 | 68篇 |
1987年 | 71篇 |
1986年 | 77篇 |
1985年 | 89篇 |
1984年 | 78篇 |
1983年 | 95篇 |
1982年 | 65篇 |
1981年 | 56篇 |
1980年 | 58篇 |
1979年 | 74篇 |
1978年 | 68篇 |
1977年 | 66篇 |
1976年 | 59篇 |
1975年 | 54篇 |
1973年 | 40篇 |
排序方式: 共有8148条查询结果,搜索用时 15 毫秒
71.
72.
Philip N. James 《Information Systems Management》2013,30(4):83-86
Abstract MORE THAN 50 PERCENT OF firms are expected to use IT outsourcing in 2006. the sourcing issue is among the top five agenda items for IT executives, as the amount of such outsourcing grows, its impact on the economies of companies and nations increases and political controversy over the consequent jobs lost to off-shore outsourcing heightens. Thus, outsourcing is, and will likely continue to be, a hot professional and political topic and a major determinant of the future of IT. 相似文献
73.
Data-intensive problems challenge conventional computing architectures with demanding CPU, memory, and I/O requirements. Experiments with three benchmarks suggest that emerging hardware technologies can significantly boost performance of a wide range of applications by increasing compute cycles and bandwidth and reducing latency. 相似文献
74.
In this paper we introduce the constrained tetrahedralization as a new acceleration structure for ray tracing. A constrained tetrahedralization of a scene is a tetrahedralization that respects the faces of the scene geometry. The closest intersection of a ray with a scene is found by traversing this tetrahedralization along the ray, one tetrahedron at a time. We show that constrained tetrahedralizations are a viable alternative to current acceleration structures, and that they have a number of unique properties that set them apart from other acceleration structures: constrained tetrahedralizations are not hierarchical yet adaptive; the complexity of traversing them is a function of local geometric complexity rather than global geometric complexity; constrained tetrahedralizations support deforming geometry without any effort; and they have the potential to unify several data structures currently used in global illumination. 相似文献
75.
Cylindrical fibre actuators have been constructed by a coextrusion method using a thermoplastic polyurethane wall and a conductive grease filler. These actuators may be operated as single fibres or bundled together as actuating ropes. Key results include the validation of Carpi’s wall pressure model [F. Carpi, D.D. Rossi, Dielectric elastomer cylindrical actuators: electromechanical modelling and experimental evaluation, Mater. Sci. Eng. C-Biomimetic Supramol. Syst. 24 (2004) 555–562] and the proof-of-concept demonstration of a technique that can be used for producing inexpensive dielectric elastomer actuators on an industrial scale. 相似文献
76.
Increasingly, software systems are constructed by integrating and composing multiple existing applications. The resulting complexity increases the need for self-management of the system. However, adding autonomic behavior to composite systems is difficult, especially when the constituent components are heterogeneous and they were not originally designed to support such interactions. Moreover, entangling the code for self-management with the code for the business logic of the original applications may actually increase the complexity of the systems, counter to the desired goal. In this paper, we address autonomization of composite systems that use CORBA, one of the first widely used middleware platforms introduced more than 17 years ago that is still commonly used in numerous systems. We propose a model, called Adaptive CORBA Template (ACT), that enables autonomic behavior to be added to CORBA applications automatically and transparently, that is, without requiring any modifications to the code implementing the business logic of the original applications. To do so, ACT uses “generic” interceptors, which are added to CORBA applications at startup time and enable autonomic behavior to be introduced later at runtime. We have developed ACT/J, a prototype of ACT in Java. We describe a case study in which ACT/J is used to introduce three types of autonomic behavior (self-healing, self-optimization, and self-configuration) to a distributed surveillance application. 相似文献
77.
The design of systems for dynamic response may involve constraints that need to be satisfied over an entire time interval
or objective functions evaluated over the interval. Efficiently performing the constrained optimization is challenging, since
the typical response is implicitly linked to the design variables through a numerical integration of the governing differential
equations. Evaluating constraints is costly, as is the determination of sensitivities to variations in the design variables.
In this paper, we investigate the application of a temporal spectral element method to the optimization of transient and time-periodic
responses of fundamental engineering systems. Through the spectral discretization, the response is computed globally, thereby
enabling a more explicit connection between the response and design variables and facilitating the efficient computation of
response sensitivities. Furthermore, the response is captured in a higher order manner to increase analysis accuracy. Two
applications of the coupling of dynamic response optimization with the temporal spectral element method are demonstrated.
The first application, a one-degree-of-freedom, linear, impact absorber, is selected from the auto industry, and tests the
ability of the method to treat transient constraints over a large-time interval. The second application, a related mass-spring-damper
system, shows how the method can be used to obtain work and amplitude optimal time-periodic control force subject to constraints
over a periodic time interval.
This research was performed while the first author held a National Research Council Research Associateship Award at the Air
Force Research Laboratory.
An early version of this paper was presented at the 46th AIAA Aerospace Sciences Meeting and Exhibit, Jan 7–10, 2008, Reno,
Nevada. 相似文献
78.
Qi Jiyang Gao Yan Hu Yao Wang Xinggang Liu Xiaoyu Bai Xiang Belongie Serge Yuille Alan Torr Philip H. S. Bai Song 《International Journal of Computer Vision》2022,130(8):2022-2039
International Journal of Computer Vision - Can our video understanding systems perceive objects when a heavy occlusion exists in a scene? To answer this question, we collect a large-scale dataset... 相似文献
79.
80.
Yucheng Zhao Jacob Misch Chang-An Wang 《Journal of Materials Science: Materials in Electronics》2016,27(6):5533-5542
MnO2 nanomaterials are synthesized via calcinations in air at various temperatures. Amorphous MnO2 masses appear between 100 and 300 °C and nanorods form above 400 °C. Transmission and scanning electron microscopy are used to observe the geometries of each material, with further structural analyses conducted using X-ray photoelectron spectroscopy, X-ray diffraction, and BET method. The electrochemical properties are investigated through galvanostatic charge/discharge cycling, electrochemical impedance spectra, and cyclic voltammetry within a three-electrode test cell filled with 1 mol L?1 Na2SO4 solution. The slightly asymmetric galvanostatic cycling curves suggest that the reversibility of the Faradaic reactions are imperfect, requiring a larger time to charge than discharge. The specific capacitances of each sample are calculated and trends are identified, proving that the samples synthesized at higher temperatures exhibit poorer electrochemical behaviors. The highest calculated specific capacitance is 175 F g?1 by the sample calcinated at 400 °C. However, the lower temperature samples exhibit more favorable geometric properties and higher overall average specific capacitances. For future research, it is suggested that surface modifications such as a carbon coating could be used in conjunction with the MnO2 nanorods to reach the electrochemical properties required by contemporary industrial applications. 相似文献