全文获取类型
收费全文 | 17608篇 |
免费 | 1946篇 |
国内免费 | 1390篇 |
专业分类
电工技术 | 1514篇 |
综合类 | 1779篇 |
化学工业 | 1802篇 |
金属工艺 | 1699篇 |
机械仪表 | 1590篇 |
建筑科学 | 1180篇 |
矿业工程 | 1291篇 |
能源动力 | 693篇 |
轻工业 | 1091篇 |
水利工程 | 634篇 |
石油天然气 | 726篇 |
武器工业 | 219篇 |
无线电 | 1309篇 |
一般工业技术 | 2047篇 |
冶金工业 | 523篇 |
原子能技术 | 196篇 |
自动化技术 | 2651篇 |
出版年
2024年 | 64篇 |
2023年 | 287篇 |
2022年 | 521篇 |
2021年 | 565篇 |
2020年 | 650篇 |
2019年 | 550篇 |
2018年 | 562篇 |
2017年 | 688篇 |
2016年 | 796篇 |
2015年 | 786篇 |
2014年 | 1168篇 |
2013年 | 1296篇 |
2012年 | 1324篇 |
2011年 | 1409篇 |
2010年 | 1098篇 |
2009年 | 1080篇 |
2008年 | 879篇 |
2007年 | 1185篇 |
2006年 | 998篇 |
2005年 | 836篇 |
2004年 | 687篇 |
2003年 | 572篇 |
2002年 | 478篇 |
2001年 | 387篇 |
2000年 | 364篇 |
1999年 | 325篇 |
1998年 | 212篇 |
1997年 | 225篇 |
1996年 | 183篇 |
1995年 | 140篇 |
1994年 | 135篇 |
1993年 | 89篇 |
1992年 | 81篇 |
1991年 | 55篇 |
1990年 | 58篇 |
1989年 | 40篇 |
1988年 | 33篇 |
1987年 | 13篇 |
1986年 | 21篇 |
1985年 | 20篇 |
1984年 | 17篇 |
1983年 | 19篇 |
1982年 | 15篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1975年 | 2篇 |
1960年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
81.
82.
宣汉——达县地区飞仙关组储层预测方法研究 总被引:1,自引:1,他引:0
在宣汉-达县地区,以往仅依据地震属性来预测飞仙关组储层分布,钻探结果与实际情况不符,为此本文提出量化分析预测结合主参数分析的新方法和新思路。在量化分析中首先对飞仙关组储层进行高分辨率反演,获得储能系数图;然后结合主振幅剖面和主频率剖面分析,对储层进行预测。在研究区,本方法的预测结果与实钻情况相吻合。 相似文献
83.
对数正态概率纸的自动生成和分布参数的自动提取 总被引:1,自引:0,他引:1
采用对数正态概率纸可以直观地判断一组数据是否服从对数正态分布,而且还可以得到对数正态分布参数,即对数均值和对数标准差。介绍对数正态概率纸自动生成和分布参数自动提取的方法以及据此开发的软件。与手工使用概率纸的常规方法相比,采用所开发的软件不但使用简单、方便,而且能提高计算结果的精度。 相似文献
84.
Color characteristics of Cu-Zn-Al alloys 总被引:4,自引:0,他引:4
COLORCHARACTERISTICSOFCu-Zn-AlALLOYS ̄①Li,Baomian;Zhang,Xiuhua(ShenyangInstituteofGoldTechnology,Shenyang110015)COLORCHARACTER... 相似文献
85.
Structural and electrical properties of brush plated ZnTe films 总被引:1,自引:0,他引:1
Zinc telluride thin films were deposited by the brush plating technique at a potential of −0.90 V (SCE) on conducting glass and titanium substrates at different temperatures in the range 30–90 °C. The films were polycrystalline in nature with peaks corresponding to the cubic phase. Direct band gap of 2.30 eV was observed. XPS studiers indicated the formation of ZnTe. Depth profiling studies indicated a uniform distribution of Zn and Te throughout the entire thickness. EDAX measurements were made on the films and it was found that there was a slight excess of Te. The carrier concentration was found to vary from 1014–1015 cm−3 with increase of substrate temperature. The mobility was found to vary from 5 to 60 cm2 V−1 s−1. 相似文献
86.
随着时间的推移,混凝土的导温系数将发生变化,为了了解参数随时间的变化规律,利用原型观测资料对导温系数进行分段反演,从而拟合出大坝混凝土导温系数随时间的变化规律. 相似文献
87.
组织光学中的Monte Carlo方法 总被引:12,自引:5,他引:7
介绍了Monte Carlo方法产生的背景、基本思想及其在组织光学应用中的重要意义,评述了其在组织光学应用中的研究进展,对其发展趋势作了展望。 相似文献
88.
“Symmetric materials” devices, where both electrodes are made of the same electrochromic materials, allow the in situ study of side reactions. Each transferred charge that is not used for the expected electrochromic reaction will cause a colour change in the whole symmetric device. Two electrochromic materials, WO3 and IrO2, are successively used to show how to obtain information about side reactions such as faradaic efficiency, reversibility and potential limits from the symmetric experiment. This in situ approach with a polymer electrolyte shows significant differences compared to results obtained with studies in aqueous electrolytes. 相似文献
89.
T. Jeevananda Siddaramaiah Taek Su Lee Joong Hee Lee O. M. Samir R. Somashekar 《应用聚合物科学杂志》2008,109(1):200-210
Polyaniline/carboxylated multi-walled carbon nanotube (PAni/c-MWNT) nanocomposites have been synthesized by micellar aided emulsion polymerization with various c-MWNTs compositions, viz., 0.5, 1, 5, and 10 wt %. The microcrystalline parameters such as the nanocrystal size (〈N〉), lattice strain (g), interplanar distance (dhkl), width of the crystallite size distribution, surface weighted crystal size (Ds), and volume of the ordered regions were calculated from the X-ray data by using two mathematical models, namely the Exponential distribution and Reinhold distribution methods. The effects of heat ageing on the microcrystalline parameters of the PAni/c-MWNT nanocomposites were also studied and the results are correlated. The thermal stability and electrical resistivity of the PAni/c-MWNT nanocomposites were examined with thermogravimetric analysis (TGA) and a conventional two-probe method. The TGA data indicate that the thermal stability of the nanocomposites improved after the incorporation of c-MWNTs. The influence of temperature on the resistivity of the nanocomposites was also measured. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008 相似文献
90.
The swelling kinetics curves of structurally defined poly(acrylic acid) hydrogel in bidistilled water at temperatures: 25, 30, 35, 40, and 45°C were determined. The possibility of kinetically explaining the isothermal swelling process by applying the following models: reaction controlled by diffusion, first order chemical reaction kinetics, and second order chemical reaction kinetics, was investigated. It was found that kinetically explaining the swelling process using these methods was limited to only certain parts of the process. The swelling process in bidistilled water was described in full range assuming that the hydrogel's swelling rate was a kinetically controlled reaction by the rate of the movement of reactive interface of hydrogel. Based on that model, the kinetic parameters, activation energy (Ea) and preexponential factor (A), of the swelling process were determined to be Ea = 35 kJ/mol and lnA = 8.6. A possible mechanism of the investigated swelling process was discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献