全文获取类型
收费全文 | 28414篇 |
免费 | 3536篇 |
国内免费 | 1586篇 |
专业分类
电工技术 | 3185篇 |
综合类 | 2424篇 |
化学工业 | 2752篇 |
金属工艺 | 4618篇 |
机械仪表 | 3369篇 |
建筑科学 | 1616篇 |
矿业工程 | 920篇 |
能源动力 | 1065篇 |
轻工业 | 1676篇 |
水利工程 | 495篇 |
石油天然气 | 2029篇 |
武器工业 | 246篇 |
无线电 | 2388篇 |
一般工业技术 | 2568篇 |
冶金工业 | 1546篇 |
原子能技术 | 445篇 |
自动化技术 | 2194篇 |
出版年
2024年 | 106篇 |
2023年 | 368篇 |
2022年 | 732篇 |
2021年 | 833篇 |
2020年 | 882篇 |
2019年 | 813篇 |
2018年 | 681篇 |
2017年 | 997篇 |
2016年 | 1138篇 |
2015年 | 1140篇 |
2014年 | 1733篇 |
2013年 | 1721篇 |
2012年 | 1986篇 |
2011年 | 2207篇 |
2010年 | 1651篇 |
2009年 | 1678篇 |
2008年 | 1513篇 |
2007年 | 1957篇 |
2006年 | 1821篇 |
2005年 | 1448篇 |
2004年 | 1328篇 |
2003年 | 1194篇 |
2002年 | 1056篇 |
2001年 | 864篇 |
2000年 | 726篇 |
1999年 | 571篇 |
1998年 | 470篇 |
1997年 | 381篇 |
1996年 | 332篇 |
1995年 | 273篇 |
1994年 | 217篇 |
1993年 | 171篇 |
1992年 | 111篇 |
1991年 | 95篇 |
1990年 | 96篇 |
1989年 | 79篇 |
1988年 | 37篇 |
1987年 | 32篇 |
1986年 | 15篇 |
1985年 | 10篇 |
1984年 | 8篇 |
1983年 | 13篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1962年 | 4篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 347 毫秒
71.
Ashok K. Vijh 《Drying Technology》1995,13(1):215-224
An attempt is made to elucidate the electrochemical aspects of the electroosmotic dewatering (EOD) of clays as reported in some recent work, especially that on interrupted DC power electroosmotic dewatering published by Rabie, Mujumdar and Weber (2). These authors showed that the dewatering by EOD stops after the DC power has been on for several minutes or hours; on interruption of their power and on short-circuiting of the electrodes, conditions can be created again for some further dewatering by DC power EOD. This discovery, of Rabie et al. is interpreted as a fuel cell effect and it is shown that it affords clues to several other electrochemical strategies for the possible enhancement of the efficiency of the EOD by DC power.
Further, the open circuit potentials observed by Rabie et al. (2) on the interruption of DC power are given an electrochemical interpretation which leads to quantitative estimates in agreement with the experimental values. 相似文献
Further, the open circuit potentials observed by Rabie et al. (2) on the interruption of DC power are given an electrochemical interpretation which leads to quantitative estimates in agreement with the experimental values. 相似文献
72.
73.
Y. W. Kim 《International Journal of Thermophysics》2002,23(4):1103-1113
A new all-spectroscopic method for depth-resolved thermal diffusivity measurement of metallic specimens has been demonstrated. The method entails measurement of the mass entrained into a laser-produced plasma (LPP) plume in such a manner that the plume is representative of the specimen in elemental composition. Both the abundance of matter and its elemental composition are measured by time-resolved spectroscopy for each LPP plume. In order to delineate the morphology versus composition basis of the depth dependence, a new study on a Nichrome ribbon specimen heated by ohmic heating in a vacuum is presented. A set of depth-resolved thermal diffusivity measurements is carried out, while noting the attendant changes in the spectral emissivity and elemental composition at succeeding ablation layers. Additional measurements are carried out after the specimen has been treated under varying heating conditions. Preferential diffusion of chromium at high temperatures has been found to contribute to the dynamics of surface thermophysical properties at high temperatures. Representative LPP ablation is well suited for removal of surface impurities prior to thermophysical property measurements by the pulse heating technique. 相似文献
74.
Buffalo milk Cheddar cheese samples of different ages were analysed for compositional attributes (CA), ripening indices (RI) and Instron Textural Profile (ITP). All samples were compositionally alike, except for pH and salt-in-moisture (SM) contents. RI showed significant variations. CA and RI showed highly significant correlations within themselves and with each other, except for moisture with pH, SM with moisture, MNFS, Fat and FDM and Fat with MNFS. The ITPs of cheeses showed significant variations and had highly significant intercorrelations indicating their interdependence. CA (except moisture and MNFS) and RI showed a highly significant correlationship with ITPs. Moisture content showed a highly significant correlationship with all ITPs, except cohesiveness and springiness, where it was significant. MNFS content showed significant correlations only with hardness and brittleness. Stepwise regression analysis revealed that MI was the most predominant factor influencing cheese texture, followed by pH, SM, FDM and TVFA. Knowing Ca and RI, the textural properties of cheeses can be forecast through mathematical equations. Similarly the age of cheese can also be predicted if RI and/or textural properties are known. 相似文献
75.
离子注入对Cr12MoV钢表面组织结构和力学性能的影响 总被引:1,自引:0,他引:1
研究了Cr12MoV钢离子注入层的显微组织特征及其对表面性能的影响。结果表明,离子注入使Cr12MoV钢的表面硬度和耐磨性能得到显著改善,且存在着一个最佳的注入剂量,约为3×10^1^7N^+/cm^2左右。离了注入在Cr12MoV钢表面层中形成了大量细小弥散的第二相粒子,并使α-Fe晶格发生严重畸变,从而引起材料表面强化。 相似文献
76.
Sandra A. Yost Peter H. Bauer Kasyapa Balemarthy 《Multidimensional Systems and Signal Processing》1996,7(2):211-220
This paper addresses the BIBO (bounded-input bounded-output) stability of a class of discrete 2-D quarter-plane filters in the presence of nonessential singularities of the second kind (NSSK's) on the unit bidisk. Conditions under which the double bilinear transformation (DBT) preserves stability are derived. The results presented here also extend the class of systems whose stability can be predicted. Use of the inverse DBT to produce a continuous equivalent of the discrete 2-D transfer function allows easy application of a continuous-domain equivalent of a criterion developed by Dautov. The necessary and sufficient condition for stability derived in this work provides a simple check for the class of systems under consideration. From this class of systems, it is also possible to construct stable pairs of mutually inverse transfer functions. 相似文献
77.
本文介绍了磨前滚刀滚切齿轮的最大根切量和磨后的渐开线长度计算,并建立了数学模型。为更加直观起见,还建立了模拟滚齿的数学模型。并在实验的基础上提出了参考标准。 相似文献
78.
本文主要从经济角度分析净水厂实际生产情况及经济技术指标等方面的数据。阐述福州西区水厂一期滤池由原先双阀滤池改造成V型滤池的经济性。 相似文献
79.
In order to develop a basic electrode with low fume and good usability, a uew slag system has been designed after analyzing several basic electrode slag systems. Then in view of uniform design method, arranging the experiment points by it, the influenced laws of the uew system coating compouents on the arc stability had been searched. In the formula, niue coating compouents were taken as independent variables and they were divided into six levels in all twenty-four experiments. The arc stability was taken as function and taken down the data when welding and then put them into the computer to be processed statistically. The analysis results give the mathematical model and trend diagrams between independent variables and the function. They indicate that the effects of many coating compouents on the arc stability are in the mutual form. The mutual effects between CaCO3 and BaF2, BaF2 and BaCO3 , increases the arc stability separately. While the mutual effects between CaF2 and iron powder, the square item of iron powder itself decreases the arc stability separately. 相似文献
80.