全文获取类型
收费全文 | 61700篇 |
免费 | 5757篇 |
国内免费 | 2627篇 |
专业分类
电工技术 | 3646篇 |
技术理论 | 4篇 |
综合类 | 3648篇 |
化学工业 | 10230篇 |
金属工艺 | 3484篇 |
机械仪表 | 4105篇 |
建筑科学 | 4309篇 |
矿业工程 | 1730篇 |
能源动力 | 1989篇 |
轻工业 | 4433篇 |
水利工程 | 1195篇 |
石油天然气 | 2812篇 |
武器工业 | 553篇 |
无线电 | 7568篇 |
一般工业技术 | 7834篇 |
冶金工业 | 3271篇 |
原子能技术 | 874篇 |
自动化技术 | 8399篇 |
出版年
2024年 | 221篇 |
2023年 | 965篇 |
2022年 | 1681篇 |
2021年 | 2449篇 |
2020年 | 1855篇 |
2019年 | 1647篇 |
2018年 | 1890篇 |
2017年 | 1970篇 |
2016年 | 1945篇 |
2015年 | 2487篇 |
2014年 | 3203篇 |
2013年 | 3926篇 |
2012年 | 4353篇 |
2011年 | 4573篇 |
2010年 | 3922篇 |
2009年 | 3857篇 |
2008年 | 3604篇 |
2007年 | 3360篇 |
2006年 | 3192篇 |
2005年 | 2699篇 |
2004年 | 2078篇 |
2003年 | 1895篇 |
2002年 | 1999篇 |
2001年 | 1715篇 |
2000年 | 1383篇 |
1999年 | 1334篇 |
1998年 | 1161篇 |
1997年 | 848篇 |
1996年 | 752篇 |
1995年 | 647篇 |
1994年 | 488篇 |
1993年 | 422篇 |
1992年 | 302篇 |
1991年 | 243篇 |
1990年 | 191篇 |
1989年 | 145篇 |
1988年 | 139篇 |
1987年 | 89篇 |
1986年 | 98篇 |
1985年 | 58篇 |
1984年 | 51篇 |
1983年 | 31篇 |
1982年 | 27篇 |
1981年 | 30篇 |
1980年 | 21篇 |
1979年 | 19篇 |
1978年 | 17篇 |
1977年 | 21篇 |
1976年 | 24篇 |
1975年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
This paper investigates the catalytic ignition of the H2/O2/CO2 mixture on platinum in a stagnation flow at atmospheric pressure experimentally and numerically. We measure the ignition temperatures of the gas mixtures flowing towards resistively heated platinum with various composition ratios and various diluent gases of N2, Ar and CO2. Compared with N2 or Ar, the CO2 dilution shows higher ignition temperature by about 50 K, even at the same composition ratio. The ignition temperature increase is proportional to the dilution ratio. Through the numerical simulation, it is illustrated that higher ignition temperature is caused by the adsorption of CO2 and following dissociation on platinum surface, which was to date considered negligible in catalytic combustion. 相似文献
72.
73.
To determine three‐dimensional fiber orientation states in injection‐molded short‐fiber composites, a confocal laser scanning microscope (CLSM) is used. Since the CLSM optically sections the specimen, more than two images of the cross sections on and below the surface of the composite can be obtained. Three‐dimensional fiber orientation states can be determined by using geometric parameters of fiber images obtained from two parallel cross sections. For experiments, carbon‐fiber‐reinforced polystyrene is examined by the CLSM and geometric parameters of fibers on each cross‐sectional plane are measured by an image analysis. In order to describe fiber orientation states compactly, orientation tensors are determined at different positions of the prepared specimen. Three‐dimensional orientation states are obtained without any difficulty by determining the out‐of‐plane angles utilizing fiber images on two parallel planes acquired by the CLSM. Orientation states are different at different positions and show the shell–core structure along the thickness of the specimen. Fiber orientation tensors are predicted by a numerical analysis and the numerically predicted orientation states show good agreement with measured ones. However, some differences are found at the end of cavity. They may result from the fountain flow effects, which are not considered in the numerical analysis. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 500–509, 2003 相似文献
74.
Bong Keun Kim Wan Kyun Chung 《Industrial Electronics, IEEE Transactions on》2003,50(6):1207-1216
Disturbance-observer (DOB)-based controller design is one of the most popular methods in the field of motion control. In this paper, the generalized disturbance compensation framework, named the robust internal-loop compensator (RIC) is introduced and an advanced design method of a DOB is proposed based on the RIC. The mixed sensitivity optimization problem, which is the main issue of DOB design, is also solved through the parametrization of the DOB in the RIC framework. Differently from conventional methods, the Q-filter is separated from the mixed sensitivity optimization problem and a systematic design law for the DOB is proposed. This guarantees the robustness and optimality of the DOB and enables the design for unstable plants. 相似文献
75.
介绍了采用同心旋转调制盘和相应的逻辑门积分计数的积累检测技术的基本原理,并给出采用同心旋转调制盘的红外检测系统的基本结构,介绍了同心旋转调制盘系统的设计方法,通过对实验结果进行分析,表明同心旋转调制盘技术在红外检测系统应用中可以大大地改善系统的性能,提高了探测概率,降低了虚警概率。同时分析了该系统存在的问题,为红外检测技术的进一步发展提供一些经验。 相似文献
76.
本文介绍了欧洲轿车新战略决策,也即:将要提高轿车的电池电压,,阻燃材料的比率和工作温度;Synolite5001-T-1牌聚酯树脂的阻燃防炎性能优于酚醛树脂。 相似文献
77.
Douay M. Xie W.X. Taunay T. Bernage P. Niay P. Cordier P. Poumellec B. Dong L. Bayon J.F. Poignant H. Delevaque E. 《Lightwave Technology, Journal of》1997,15(8):1329-1342
A comprehensive survey of photosensitivity in silica glasses and optical fiber is reviewed. Recent work on understanding the mechanisms contributing to germanium or aluminum doped fiber photosensitivity is discussed within the framework of photoelastic densification models 相似文献
78.
Pi-Yu Chung Hajj I.N. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》1997,5(2):233-237
This paper presents a technique to correct multiple logic design errors in a gate-level netlist. A number of methods have been proposed for correcting single logic design errors. However, the extension of these methods to more than one error is still very limited. We direct our attention to circuits with a low multiplicity of errors. By assuming different error dependency scenarios, multiple errors are corrected by repeatedly applying a single error search and correction algorithm. Experimental results on correcting double-design errors and triple-design errors on ISCAS and MCNC benchmark circuits are included 相似文献
79.
禹门口提水工程干渠上的十几座大型钢筋混凝土渡槽采用现浇混凝土施工方案。经过十几座渡槽的施工及通水检验,证明现浇施工技术与工艺已经成熟。本文就施工中遇到的高大排架外形与垂直度控制、槽身模板制做与固定、模具的空中支撑、运输与入仓办法等做以简单介绍。 相似文献
80.
本文提出新型布线算法,集李氏迷宫法与线搜索法的长处为一体,以饱和带法进行动态排序,以线搜索法确定借孔位置,然后用李氏法进行单层布线,获得最佳路径,从而达到线型好,布通率高的效果。 相似文献