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E-learning systems provide a promising solution as an information exchanging channel. Improved technologies could mean faster and easier access to information but do not necessarily ensure the quality of this information; for this reason it is essential to develop valid and reliable methods of quality measurement and carry out careful information quality evaluations. This paper proposes an assessment model for information quality in e-learning systems based on the quality framework we proposed previously: the proposed framework consists of 14 quality dimensions grouped in three quality factors: intrinsic, contextual representation and accessibility. We use the relative importance as a parameter in a linear equation for the measurement scheme. Formerly, we implemented a goal-question-metrics approach to develop a set of quality metrics for the identified quality attributes within the proposed framework. In this paper, the proposed metrics were computed to produce a numerical rating indicating the overall information quality published in a particular e-learning system. The data collection and evaluation processes were automated using a web data extraction technique and results on a case study are discussed. This assessment model could be useful to e-learning systems designers, providers and users as it provides a comprehensive indication of the quality of information in such systems. 相似文献
94.
César MarconAuthor VitaeNey CalazansAuthor Vitae Edson MorenoAuthor VitaeFernando MoraesAuthor Vitae Fabiano HesselAuthor VitaeAltamiro SusinAuthor Vitae 《Journal of Parallel and Distributed Computing》2011,71(5):714-728
This paper describes CAFES, an extensible, open-source framework supporting several tasks related to high-level modeling and design of applications employing complex intrachip communication infrastructures. CAFES comprises several built-in models, including application, communication architecture, energy consumption and timing models. It also includes a set of generic and specific algorithms and additional supporting tools, which jointly with the cited models allow the designer to describe and evaluate applications requirements and constraints on specified communication architectures. Several examples of the use of CAFES underline the usefulness of the framework. Some of these are approached in this paper: (i) a realistic application captured at high-level that has its computation time estimated after mapping at the clock cycle level; (ii) a multi-application system that is automatically mapped to a large intrachip network with related tasks occupying contiguous areas in the chip layout; (iii) a set of mapping algorithms explored to define trade-offs between run time and energy savings for small to large intrachip communication architectures. 相似文献
95.
96.
K. Geihs P. Barone F. Eliassen J. Floch R. Fricke E. Gjorven S. Hallsteinsen G. Horn M. U. Khan A. Mamelli G. A. Papadopoulos N. Paspallis R. Reichle E. Stav 《Software》2009,39(4):385-422
Driven by the emergence of mobile and pervasive computing there is a growing demand for context‐aware software systems that can dynamically adapt to their run‐time environment. We present the results of project MADAM that has delivered a comprehensive solution for the development and operation of context‐aware, self‐adaptive applications. The main contributions of MADAM are (a) a sophisticated middleware that supports the dynamic adaptation of component‐based applications, and (b) an innovative model‐driven development methodology that is based on abstract adaptation models and corresponding model‐to‐code transformations. MADAM has demonstrated the viability of a general, integrated approach to application‐level adaptation. We discuss our experiences with two real‐world case studies that were built using the MADAM approach. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
97.
Application frameworks are a powerful means to reduce software development costs while improving quality. However, at the same time they are difficult to select and understand, as well as hard to learn, use, and debug effectively and efficiently. In this paper we report the story of eConference, a distributed conferencing system that was developed as part of a broader research effort. Here we discuss the lessons learned from the evolution of our conferencing tool over four generations, which have been necessary to find good frameworks and build a flexible distributed tool. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
98.
Michael?DeBoleEmail author Ramakrishnan?Krishnan Varsha?Balakrishnan Wenping?Wang Hong?Luo Yu?Wang Yuan?Xie Yu?Cao N.?Vijaykrishnan 《International journal of parallel programming》2009,37(4):417-431
Degradation of device parameters over the lifetime of a system is emerging as a significant threat to system reliability.
Among the aging mechanisms, wearout resulting from Negative Bias Temperature Instability (NBTI) is of particular concern in
deep submicron technology generations. While there has been significant effort at the device and circuit level to model and
characterize the impact of NBTI, the analysis of NBTI’s impact at the architectural level is still at its infancy. To facilitate
architectural level aging analysis, a tool capable of evaluating NBTI vulnerabilities early in the design cycle has been developed
that evaluates timing degradation due to NBTI. The tool includes workload-based temperature and performance degradation analysis
across a variety of technologies and operating conditions, revealing a complex interplay between factors influencing NBTI
timing degradation. 相似文献
99.
In this paper we discuss regularization of images that take their value in matrix Lie groups. We describe an image as a section
in a principal bundle which is a fibre bundle where the fiber (the feature space) is a Lie group. Via the scalar product on
the Lie algebra, we define a bi-invariant metric on the Lie-group manifold. Thus, the fiber becomes a Riemannian manifold
with respect to this metric. The induced metric from the principal bundle to the image manifold is obtained by means of the
bi-invariant metric. A functional over the space of sections, i.e., the image manifolds, is defined. The resulting equations
of motion generate a flow which evolves the sections in the spatial-Lie-group manifold. We suggest two different approaches
to treat this functional and the corresponding PDEs. In the first approach we derive a set of coupled PDEs for the local coordinates
of the Lie-group manifold. In the second approach a coordinate-free framework is proposed where the PDE is defined directly with respect to the Lie-group elements. This is a parameterization-free
method. The differences between these two methods are discussed. We exemplify this framework on the well-known orientation
diffusion problem, namely, the unit-circle S
1 which is identified with the group of rotations in two dimensions, SO(2). Regularization of the group of rotations in 3D and 4D, SO(3) and SO(4), respectively, is demonstrated as well.
相似文献
Nir SochenEmail: |
100.
This study presents a fabrication-based approach to improve the curl-up effect in complementary metal oxide semiconductor (CMOS) multilayer large-area planar structures. Control of the residual stress of CMOS multilayer microstructures is necessary for development of microelectromechanical systems (MEMS) sensors such as accelerometers and micromirrors. In this work, 3D symmetric geometry can be used to overcome effectively the residual stresses in CMOS multilayer microstructures. To demonstrate this concept, a symmetric multilayer flat-plane is fabricated and release-etched using an isotropic plasma etching process. The isotropic etch characteristics and lateral undercut can be controlled using a chamber pressure of 0.47 ± 0.2 Torr. A flat-plane structure with an area of 500 μm × 500 μm is fabricated using multilayer materials, including four metal and three silicon dioxide layers. Based on this approach, the measured results show the residual stress effect can be minimized in CMOS multilayer microstructures, and furthermore the curl-up effect of flat-plane is less than 2 μm across the 500 μm × 500 μm area. 相似文献