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71.
本文通过对目前我国商业步行街现状的调研与分析,在现代人对现代商业活动的需求的基础上,提出了对现代步行街的设计导则,揭示了现代商业步行街的巨大发展前景。 相似文献
72.
某盐渍湖软土路基公路工程采用填石挤淤和强夯施工技术对软土路基进行了处理.在施工过程中,通过采用平板载荷检测,来评估地基承载力能否达到设计要求,并通过钻探和重型动力触探试验对处理后的路基进行了检测.结果表明,其处理效果能满足设计和工程质量要求. 相似文献
73.
Stadium disasters statistic analysis indicated that egress congestion is the major cause of crowd stampede trampling and crushing incidents. In this paper a stranded-crowd model (SCM) for stadium egress is put forward with previous works. The empirical relation between density and velocity of crowd movement have been summarized, and then the crowd-flow rate as a function of density deduced. The paper presents experimental results for this model under emergency conditions and discusses the following observations: the data show egress stranded number of crowd for different time ranges and various relations of flow rate and density can be calculated; furthermore, comparing the results of different egress width with the same formula for the movement in a stadium straight passage. This comparison shows an unexpected conformance between the egress width and stranded number of panic crowd. Based on the results, SCM shows great value in dealing with stadium, especially 2008 Beijing Olympic stadium, egress performance design, selecting and optimizing of routes and so on. 相似文献
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75.
随着IP业务的超常规发展,传输瓶颈日渐显现出来;以安微电信骨干传输网的发展规划为例,介绍安微电信宽带骨干传输网的构建方案。 相似文献
76.
Chau-Jy Lin 《Computers & Mathematics with Applications》1996,32(12):77-91
For an arbitrary n × n matrix A and an n × 1 column vector b, we present a systolic algorithm to solve the dense linear equations Ax = b. An important consideration is that the pivot row can be changed during the execution of our systolic algorithm. The computational model consists of n linear systolic arrays. For 1 ≤ i ≤ n, the ith linear array is responsible to eliminate the ith unknown variable xi of x. This algorithm requires 4n time steps to solve the linear system. The elapsed time unit within a time step is independent of the problem size n. Since the structure of a PE is simple and the same type PE executes the identical instructions, it is very suitable for VLSI implementation. The design process and correctness proof are considered in detail. Moreover, this algorithm can detect whether A is singular or not. 相似文献
77.
Ronald P. Koopman 《Chemical Engineering Communications》1988,63(1):61-86
Large scale spills of volatile cryogenic or pressurized ambient temperature liquids often produce denser-than-air clouds which disperse in the atmosphere in a manner that is different than trace gases. These differences are due to density or gravity-induced effects such as turbulence damping from the stable density stratification, alteration of the ambient velocity field due to gravity flow, and the source momentum flux. Also important are thermodynamic effects such as aerosol formation and flash vaporization upon release, evaporative cooling, or heat transfer from the ground modifying cloud buoyancy and turbulence. In addition, chemical reaction effects such as hydrolysis with atmospheric water vapor, polymerization, or decomposition which also affects cloud density and thermodynamics can be important. These effects are very important close to the release point but also can have dramatic effects on the cloud as it disperses downwind.
Large scale tests involving releases of heavy gases have been conducted since the early 1970's. These tests have resulted in the discovery of previously unknown and important effects, the accumulation of data for model validation, as well as accident simulation and evaluation of accident mitigation equipment and techniques. A review of recent tests and some of the important results will be presented and examples from recent test series will be used in a review of our current understanding of dense gas dispersion.
The status of computer modeling in this field will also be reviewed with an emphasis on the problems associated with Gaussian models and recent progress in intermediate and 3D conservation equation models. Two of these models, FEM3 and SLAB will be compared to data so that the observed phenomena can be understood and so that predictions can be made regarding the consequences of accidental spills of sizes of concern to industry. FEM3 simulates the dispersion of the released gas by solving the time-dependent, three-dimensional conversion equations of mass, momentum, energy, and species. This model is used as a research tool and is designed to simulate as closely as possible the physics and thermodynamics governing the dispersion process. Steady-State SLAB is based on the crosswind-averaged form of the conservation equations, using similarity profiles to determine the crosswind dependence. It also conserves mass, momentum, energy and species, but is inherently one-dimensional, and is computationally simple and fast to use. 相似文献
Large scale tests involving releases of heavy gases have been conducted since the early 1970's. These tests have resulted in the discovery of previously unknown and important effects, the accumulation of data for model validation, as well as accident simulation and evaluation of accident mitigation equipment and techniques. A review of recent tests and some of the important results will be presented and examples from recent test series will be used in a review of our current understanding of dense gas dispersion.
The status of computer modeling in this field will also be reviewed with an emphasis on the problems associated with Gaussian models and recent progress in intermediate and 3D conservation equation models. Two of these models, FEM3 and SLAB will be compared to data so that the observed phenomena can be understood and so that predictions can be made regarding the consequences of accidental spills of sizes of concern to industry. FEM3 simulates the dispersion of the released gas by solving the time-dependent, three-dimensional conversion equations of mass, momentum, energy, and species. This model is used as a research tool and is designed to simulate as closely as possible the physics and thermodynamics governing the dispersion process. Steady-State SLAB is based on the crosswind-averaged form of the conservation equations, using similarity profiles to determine the crosswind dependence. It also conserves mass, momentum, energy and species, but is inherently one-dimensional, and is computationally simple and fast to use. 相似文献
78.
79.
居住区无障碍设计与残障人群特征 总被引:1,自引:0,他引:1
在居住区中,对无障碍设施有需求的人群,不仅包括传统意义上的残疾人,还应包括老年人、幼年儿童等对居住环境使用有困难的群体.因此,要科学地对残疾人、老年人和儿童的生理、心理、行为进行分析,寻找他们的特殊需求,为有针对性的无障碍设计做准备. 相似文献
80.
在LTE网络大规模部署的现阶段,4G用户规模和业务量持续攀高,4G手机渗透率迅速提升,而语音业务作为运营商重要的收入来源,其重要性不言而喻.针对LTE的语音终极实现方案VoLTE(Voice over LTE),研究了实现VoLTE的关键技术,分析了影响语音质量的多种因素,提出了一种基于E-model的VoLTE语音性能评估方法,在LTE网络率先部署的密集城区场景中,基于不同网络配置和并发用户数,对VoLTE业务性能进行仿真,并采用E模型进行语音质量分析,最终实现对VoLTE的语音性能评估. 相似文献