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51.
亚磷酸三苯酯在A3钢表面成膜特点和结构 总被引:1,自引:0,他引:1
用扫描电镜(SEM)分析了亚磷酸三苯酯在A3钢表面所 成膜的微观形貌特征.结果表明:亚磷酸三苯酯在A3钢表面所成的膜具有三维结构.经 红 外光谱(IR)指认亚磷酸三苯酯与铁离子在A3钢表面形成配合物,由此推断了配位化合物的可 能结构. 相似文献
52.
Surface integrity in finish hard turning of case-hardened steels 总被引:1,自引:0,他引:1
Highly stressed steel components, e.g., gears and bearing parts, are appropriate applications for hard turning. Therefore, the process effects on significant engineering properties of work materials have to be carefully analyzed. Roughness, residual stresses, and white layers as parts of surface integrity, are functions of the machining parameters and of the cuttability of the cutting edge, i.e. of the tool wear.The aim of this work was to study the influence of feed rate, cutting speed, and tool wear on the effects induced by hard turning on case-hardened 27MnCr5 gear conebrakes and to point out the technical limitations in mass production. 相似文献
53.
T. Nguyen I. Zarudi L.C. Zhang 《International Journal of Machine Tools and Manufacture》2007,47(1):97-106
This paper studies an innovative development of a steel grinding–hardening technology using an inert cryogen—liquid nitrogen. It was found that phase transformations took place during grinding with the application of liquid nitrogen and resulted in hardened surface layer in a ground component. The layer had a fine laths martensite structure which gave rise to a remarkably high hardness. It was also shown that the treatment can produce superior surface integrity, with compressive surface residual stresses and without surface oxidation. Due to the inert nature of the liquid nitrogen, the grinding process becomes environmentally conscious. 相似文献
54.
Characterizing steel tube for hydroforming applications 总被引:1,自引:0,他引:1
B. S. Levy C. J. Van Tyne J. M. Stringfield 《Journal of Materials Processing Technology》2004,150(3):280-289
With the increased use of tubular steel products, especially for hydroforming applications, it is important to be able to predict the performance of tube from sheet tensile tests. In the present study, two aluminum killed draw quality (AKDQ) steels and one high strength low alloy (HSLA) steel were evaluated. Tensile properties and plastic strain ratios were measured on sheet material in the longitudinal and transverse directions. Axial tensile tests were performed on material extracted from production tubes. Material from quasi tubes, which are strip material bent to the same curvature as the tubes but not welded or sized, was also tested. Residual stresses in the production and quasi tube were determined by displacement methods. A hydraulic burst test was performed on the production tubes to simulate a hydroforming operation. Effective strains resulting from tubemaking are calculated for two discrete operations: bending and sizing. For the production tubes, a linear relationship was found between a load factor (strength times thickness) and effective sizing strain. The relationship between load factor and residual stress was also linear. Predictions of the maximum pressure and the strain at instability during a hydraulic burst test are shown to compare favorably with experimental values, based on flat sheet properties and tubemaking strains. The prediction of the yield strength in the tube based on flat sheet properties is shown to be fairly accurate when the effective sizing strain is small compared to the effective bending strain. 相似文献
55.
为研究压缩性土体在孔隙水压力下降下所引起的孔隙变化特征,选取孔隙度及分形维数作为评判指标,以西安D7地裂缝两侧可压缩性土层为研究对象,借助三维CT扫描成像技术,依托Matlab计算平台及VG Studio Max图像处理软件,对在水位下降过程中可压缩性土体压缩变形引起的孔隙度和分形维数孔隙变化进行定量评价,并探讨了固结压缩过程中土体孔隙分形维数的变化规律及其影响因素。研究表明:孔隙度随压缩进行大幅降低,由压缩前4.36%降至0.61%;土体分形维数与孔隙度、上覆压力均呈线性相关性,相关系数分别为0.947 2和0.966 0;而且分形维数可以很好的表征孔隙分布特点,是孔隙度的有效补充;通过分析土样孔隙度与分形维数关系,为后期建立区域上地裂缝—地下水开采耦合模型提供参数赋值基础。 相似文献
56.
加快创新开发,开拓聚氯乙烯压力管道系统的新局面 总被引:5,自引:0,他引:5
近年来聚氯乙烯管道取得了重大进步。PVC-M管材(改性聚氯乙烯管材)、PVC-O管材(取向聚氯乙烯管材)兼有非凡的强度和韧度,和传统的硬聚氯乙烯管材比可以采用较高的设计应力,显著地节约材料。 相似文献
57.
关健生 《计算机工程与应用》2014,(12):137-143
针对三维人脸识别中受光照、姿态、表情等变化而影响识别性能的问题,提出了一种原型超平面学习算法。利用SVM将弱标记数据集中的每个样本表示为一个原型超平面中层特征,使用学习组合系数从未标记的通用数据集中选择支持向量稀疏集;借助于Fisher准则最大化未标记数据集的判别能力,使用迭代优化算法求解目标函数;利用SILD进行特征提取,余弦相似性度量完成最终的人脸识别。在USCD/Honda、FRGC v2、LFW及自己搜集的人脸数据集上的实验结果表明,该算法优于其他几种三维人脸识别算法。 相似文献
58.
在基于移动锚节点的三维传感器网络节点自定位算法SNLSFA(Sensor Node Localization Scheme based on Flying Anchors)的基础上,提出了一种新的基于移动锚节点与多级通信的三维传感器网络节点自定位算法SNLSFAMC(Sensor Node Localization Scheme based on Flying Anchors and Multi-level Communication)。首先由移动锚节点提供3个或4个辅助定位点,再由辅助定位点得到两条非平行线段,然后过线段中点分别做垂直于线段的平面,经两平面相交后得到一条经过待定位节点的直线,最后利用辅助定位点与待定位节点之间的距离作为通信半径即可得到待定位节点的位置。仿真结果表明,与SNLSFA相比,在相同锚节点数量下,SNLSFAMC提高了定位精度,且在相同定位精度下,SNLSFAMC降低了对锚节点数量的需求,提高了算法的响应时间。 相似文献
59.
60.
K. Bouzek R. Chmelíková M. Paidar H. Bergmann 《Journal of Applied Electrochemistry》2003,33(2):205-215
A study was made of the influence of process parameters on the mass-transfer coefficient in a flow-through cell with a cascade of rotating drums partially filled with conductive particles (called the vertically moving particle bed). Copper deposition from an acidic sodium sulphate solution was used as the model reaction. To evaluate the experimental data a macrohomogeneous mathematical model of potential and current density distribution inside the cell was developed. The electrolyte flow distribution between the empty space above the particle bed and through the bed was evaluated. On the basis of these results the following correlation is proposed:
where the first term corresponds to the packed bed electrode and the second term represents the contribution of bed rotation. It is valid for bed porosity of 45%, cathode drum rotation rates between 0.047 and 0.120 Hz (i.e., 2.8 to 7.2 rpm) and a Re
p range of 0.003 to 0.013. 相似文献