全文获取类型
收费全文 | 23995篇 |
免费 | 2999篇 |
国内免费 | 1544篇 |
专业分类
电工技术 | 2608篇 |
综合类 | 2760篇 |
化学工业 | 2902篇 |
金属工艺 | 736篇 |
机械仪表 | 1551篇 |
建筑科学 | 1574篇 |
矿业工程 | 559篇 |
能源动力 | 682篇 |
轻工业 | 4007篇 |
水利工程 | 461篇 |
石油天然气 | 1447篇 |
武器工业 | 282篇 |
无线电 | 1919篇 |
一般工业技术 | 1933篇 |
冶金工业 | 591篇 |
原子能技术 | 193篇 |
自动化技术 | 4333篇 |
出版年
2024年 | 159篇 |
2023年 | 395篇 |
2022年 | 758篇 |
2021年 | 880篇 |
2020年 | 913篇 |
2019年 | 782篇 |
2018年 | 751篇 |
2017年 | 897篇 |
2016年 | 920篇 |
2015年 | 1019篇 |
2014年 | 1494篇 |
2013年 | 1560篇 |
2012年 | 1836篇 |
2011年 | 1894篇 |
2010年 | 1360篇 |
2009年 | 1411篇 |
2008年 | 1282篇 |
2007年 | 1520篇 |
2006年 | 1320篇 |
2005年 | 1122篇 |
2004年 | 935篇 |
2003年 | 860篇 |
2002年 | 747篇 |
2001年 | 598篇 |
2000年 | 542篇 |
1999年 | 405篇 |
1998年 | 355篇 |
1997年 | 316篇 |
1996年 | 262篇 |
1995年 | 237篇 |
1994年 | 206篇 |
1993年 | 155篇 |
1992年 | 153篇 |
1991年 | 100篇 |
1990年 | 95篇 |
1989年 | 81篇 |
1988年 | 50篇 |
1987年 | 28篇 |
1986年 | 26篇 |
1985年 | 25篇 |
1984年 | 20篇 |
1983年 | 20篇 |
1982年 | 13篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1976年 | 3篇 |
1962年 | 2篇 |
1957年 | 2篇 |
1956年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
Sven Beyer Christian Jacobi Daniel Kröning Dirk Leinenbach Wolfgang J. Paul 《International Journal on Software Tools for Technology Transfer (STTT)》2006,8(4-5):411-430
In the verified architecture microprocessor (VAMP) project we have designed, functionally verified, and synthesized a processor
with full DLX instruction set, delayed branch, Tomasulo scheduler, maskable nested precise interrupts, pipelined fully IEEE
compatible dual precision floating point unit with variable latency, and separate instruction and data caches. The verification
has been carried out in the theorem proving system PVS. The processor has been implemented on a Xilinx FPGA.
A shorter version of this article with the title “Instantiating uninterpreted functional units and memory system: functional
verification of the VAMP” appeared in [8]. The work reported here was done while all the authors were with Saarland University. 相似文献
33.
34.
稳定主槽是当前黄河下游河道治理的关键。窄深河槽具有很强的泄洪能力与输沙能力,是主槽整治追求的目标。黄河下游均是顺直微弯河道,河道水流最基本的主导机理是沿着阻力最小的方向流动,走直路、走近路,主槽整治设计流路应以顺直为上策。当前有必要对微弯整治方案进行再认识,实现对其否定之否定的提高。控制性弯道整治、对口丁坝整治、节点整治都属于双岸整治的范畴,对双岸整治的方向应予肯定。今后的整治应从微弯整治向节点整治发展,逐步过渡到以节点整治为主,最终达到稳定河势流路、高效排洪输沙之目的。 相似文献
35.
《Petroleum Science and Technology》2007,25(7):915-923
Polymer modified bitumen (PMB) is used in various construction applications, especially in motorways. The aim of this study is to improve features of 60/70 penetration grade, modified bitumen used on highways. Increasing the sensitivity to temperature and oxidation resistance are very important points for the modified bitumen. This condition was provided by reacting the carboxylic acid groups in asphaltene with the reactive ethylene terpolymer to form ester. Reactive ethylene terpolymer (RETP) and ethylene terpolymer (ETP) manufactured by DuPont USA were used as additives in this study. Infrared Spectrophotometer (IR) graphics and optical pictures of the modified bitumen have been examined. It has been observed that the softening point has increased on the other hand, the penetration and ductility values have decreased according to the test results. 相似文献
36.
Abd El-Shafy A. Nafeh Faten H. Fahmy Essam M. Abou El-Zahab 《Solar Energy Materials & Solar Cells》2003,75(3-4):723-728
In this paper the implementation of a suggested stand-alone PV system, for maximum-power point tracking (MPPT), is carried out. Also, this paper presents a comparative study, through experimental work, between the conventional PI controller and the fuzzy logic controller (FLC) under different atmospheric conditions. The implemented system with both the PI controller and the FLC gives a good maximum-power operation of the PV array, but the tracking capability for different optimum operating points is better and faster for the case of using the FLC compared to the case of using the PI controller. 相似文献
37.
Johann Vollmann Heinrich Grausgruber Helmut Wagentristl Heinrich Wohleser Pavel Michele 《Journal of the science of food and agriculture》2003,83(15):1581-1586
The presence of protease inhibitors in soybean prohibits the utilisation of the raw beans for food and feed. However, little information is available about environmental influences and the effects of nitrogen and sulphur supply on the antinutritional constituents of soybean. As these factors may influence protease inhibitors, soybean genotypes segregated according to the presence or absence of the Kunitz trypsin inhibitor have been evaluated for trypsin inhibitor activity (TIA) in field trials. TIA was affected significantly by environment (geographical location), fertilisation treatment and genotype. Environmental means of TIA were between 69.5 and 104.8 mg g?1. Nitrogen application, which caused an increase in seed protein content, resulted in a reduction in TIA by about 15% as compared with the control. Remarkably, simultaneous application of nitrogen and sulphur in the form of ammonium sulphate had a similar reductive effect on TIA to that of nitrogen application alone, although soybean protease inhibitors are rich in sulphur amino acids. Significant genetic variation in TIA was found both within the genotype class with the Kunitz inhibitor present as well as within the class lacking this inhibitor. The results suggest that TIA of soybean may be modified considerably by genetic improvement and appropriate agronomic management. Copyright © 2003 Society of Chemical Industry 相似文献
38.
微型构造表征技术在八面河油田的应用 总被引:1,自引:1,他引:0
通过对八面河油田井网密集区及井网稀疏的欠开发区的微构造研究,探讨了微构造表征技术。首先在储层多层次逐级对比的基础上,建立主力油层对比关系;密集井网条件下,则利用钻井资料编制油层顶底微型构造图;对于欠开发地区,通过人机联作自动追踪成图技术,输出2m等值线间隔构造图,建立微构造模型。以微构造模型为基础进行潜力评价,部署关键井寻找优质储量或进行开发动态调整。应用该项技术在八面河油田滚动发现了角15块等断鼻翼部局部高点,增加石油地质储量488×10~4t。 相似文献
39.
对导热油加热炉炉壁温度升高的原因进行了分析,介绍了新型复合内衬的特点,并对其技术特点、施工工艺及应用效果进行了简单阐述。 相似文献
40.
The low melting point metallic tin powder or alloy of tin and lead was blended with polypropy-lene. A kind of in situ composite has been prepared. The variations of torque were studied when the composites were mixed in Haake torque rheogeniometer. By way of capillary extrusion, effects upon rheology of the in situ com-posites of the low melting point metals (LMPM) and coupling agent for their different variety and content, were investigated. From flow curves, the results indicate that in situ composites mixed with the LMPM are a kind of pseudoplastic fluid. If the LMPM were melted, the higher the content of the LMPM , the lower apparent viscosity of composites. Meanwhile, when the coupling agent is added into composites, the viscosity of composite will go up first and drop then. This shows that the LMPM have a promoter flow action on the polypropylene. 相似文献