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81.
We have studied the CO2/CH4 mixed gas permeation through hollow fiber membranes in a permeator. An approach to characterize the true separation performance of hollow fiber membranes for binary gas mixtures was provided based on experiments and simulations. Experiments were carried out to measure the retentate and permeate flow rates and compositions at each outlet. The influences of pressure drop within the hollow fibers, non-ideal gas behavior in the mixture and concentration polarization were taken into consideration in the mathematics model. The calculation results indicate that the net influence of the non-ideal gas behavior, competitive sorption and plasticization yields the calculated CO2 permeance in a mixed gas permeator close to that obtained in pure gas tests. Whereas the CH4 permeance is higher in the mixed gas tests than that in the pure gas tests, as the plasticization caused by CO2 dominates the permeation process. As a result, the CO2/CH4 mixed gas selectivity is smaller than those obtained in pure gas tests at equivalent pressures.The calculated membrane performance shows little changes with stage cut if the effect of concentration polarization is accounted for in the calculation. The integration method developed in this study could provide more accurate characterizations of mixed gas permeance of hollow membranes than other estimation methods, as our model considers the roles of non-ideal gas behavior and concentration polarization properly. 相似文献
82.
In recent years, three‐dimensionally (3D) braided composites have attracted a great deal of attention because of their high‐impact damage tolerance and fatigue life, superior fracture toughness, and so forth, and have been used in aeronautics, military, and transportation. These advantages make them strong candidates for osteosynthesis devices. In this study, 3D braided carbon fiber–epoxy (C3D/EP) composites were produced via a simple vacuum impregnation technique. The load‐deflection curve, mechanical properties, and influence of fiber volume fraction, braiding angle, and axial reinforcing fibers were examined to determine their suitability for internal fixation devices. It is found that the C3D/EP composites have excellent toughness and do not show brittleness when fractured because of their relatively high void content. The flexural, shear, and impact strengths of the C3D/EP composites are excellent. It was shown that a C3D/EP composite with a stiffness similar to load‐bearing bones can be made while maintaining enough strength. It is concluded that a relatively higher void content and braiding angle is more suitable for the C3D/EP composites from the viewpoint of requirements of fracture fixation materials. The moisture absorption behavior and changes in mechanical properties caused by moisture uptake were evaluated. Results show that absorbed moisture slightly decreases mechanical properties of the C3D/EP composites. Contrary to the unreinforced epoxy, the moisture absorption behavior of the C3D/EP composites cannot be described with Fick's law of diffusion, probably because of the presence of voids and/or 3D fiber structure. The exact mechanisms should be proposed in further investigations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1031–1039, 2002 相似文献
83.
周海光 《红外与毫米波学报》2002,21(Z1):112-114
对布满液晶微粒的聚合物(PDLC)进行了简并四波混频及光学双稳态的研究,并在文中对相关的PDLC中的分子重取向和热效应的非线性光学效应进行了讨论. 相似文献
84.
Optical measurements of thermal diffusivity of a material 总被引:2,自引:0,他引:2
The measurement of thermal diffusivity of a material (in particular, a thin film) is important for various reasons, e.g., to predict the heat transfer in the solid subjected to a thermal process, to monitor surface composition or morphology, or to detect invisible subsurface defects like delaminations. This measurement can be done in a noncontact manner using various photothermal methods. Such methods typically involve pulsed heating of the surface by small amounts using a laser source; the decay of the surface temperature after this pulsed photothermal heating is then probed to provide the thermal diffusivity. Various probing methods have been developed in the literature, including the probing of reflection, refraction, and diffraction from the pulsed heated area, infrared thermal radiometry, and surface deformation. This paper provides an overview of such techniques and some examples of their applications. 相似文献
85.
86.
钱塘江光缆管穿越长度2454.15m,穿越深度为32m,穿越中采用了多项新技术、新工艺、新方法。文章介绍了导向孔对穿技术、套管技术、水下磁场电缆铺设技术、长距离泥浆回流技术、长距离穿越钻杆组合技术在钱塘江光缆管穿越施工中的应用。 相似文献
87.
本文将2,3-酸在甲苯溶剂中用氯化亚砜酰氯化合成2-羟基萘-3-甲酰氯,将其分别和正丁胺、正辛胺、正十二胺和正十八胺反应制得4种不同碳链长度的2-羟基萘-3-甲酰烷基胺,用对硝基苯胺重氮盐与其偶合分别制得了对硝基苯偶氮2-羟基萘-3-甲酰正丁胺、对硝基苯偶氮2-羟基萘-3-甲酰正辛胺、对硝基苯偶氮2-羟基萘-3-甲酰正十二胺和对硝基苯偶氮2-羟基萘-3-甲酰正十八胺系聚丙烯纤维用红色染料。熔点分别为189.8℃、96.2℃、115.8℃和108.1℃;热分解点分别为273.1℃、216.0℃、258.0℃和221.0℃;最大吸收波长分别为515.8nm、516.8nm、513.6nm和514.2nm。在染色条件下,4支染料在聚丙烯纤维上的上染率分别37.6%、41.8%、42.4%和44.7%。 相似文献
88.
本文简要介绍了磁光隔离器的理论、结构和分类 ,并提出了该器件今后发展的几个问题 ,最后介绍了几种磁光材料 相似文献
89.
90.
基于HOP的可调光编码/解码器的研究 总被引:1,自引:0,他引:1
提出了一种基于全息光处理器的可调光编码/解码器的实现方案。全息光处理器可以在空间进行编/解码,每个通信网络单元可以采用任意速率的数字或模拟的调制信号,它非常适合于多媒体的通信网络环境,通过对全息光处理器的折射率大小和位置的控制,当一个输入光脉冲经过光处理器中具有特定折射率的空间位置后,便可在处理器的输出端口得到合适的输出信号。本文给出了这种基于全息光处理器的可调光编码/解码器的仿真实验,结果是可行的,与以前文献中提出的结构相比,减小了硬件实现的复杂性,降低了成本和功耗,便于集成。 相似文献