全文获取类型
收费全文 | 18741篇 |
免费 | 1923篇 |
国内免费 | 1107篇 |
专业分类
电工技术 | 726篇 |
综合类 | 831篇 |
化学工业 | 5868篇 |
金属工艺 | 2057篇 |
机械仪表 | 327篇 |
建筑科学 | 206篇 |
矿业工程 | 795篇 |
能源动力 | 2991篇 |
轻工业 | 844篇 |
水利工程 | 45篇 |
石油天然气 | 1739篇 |
武器工业 | 77篇 |
无线电 | 797篇 |
一般工业技术 | 2579篇 |
冶金工业 | 1296篇 |
原子能技术 | 457篇 |
自动化技术 | 136篇 |
出版年
2024年 | 98篇 |
2023年 | 730篇 |
2022年 | 944篇 |
2021年 | 870篇 |
2020年 | 848篇 |
2019年 | 749篇 |
2018年 | 587篇 |
2017年 | 665篇 |
2016年 | 646篇 |
2015年 | 655篇 |
2014年 | 1011篇 |
2013年 | 1165篇 |
2012年 | 1249篇 |
2011年 | 1229篇 |
2010年 | 971篇 |
2009年 | 957篇 |
2008年 | 790篇 |
2007年 | 1021篇 |
2006年 | 939篇 |
2005年 | 847篇 |
2004年 | 770篇 |
2003年 | 633篇 |
2002年 | 575篇 |
2001年 | 497篇 |
2000年 | 396篇 |
1999年 | 316篇 |
1998年 | 263篇 |
1997年 | 213篇 |
1996年 | 196篇 |
1995年 | 167篇 |
1994年 | 143篇 |
1993年 | 111篇 |
1992年 | 83篇 |
1991年 | 76篇 |
1990年 | 98篇 |
1989年 | 50篇 |
1988年 | 40篇 |
1987年 | 25篇 |
1986年 | 15篇 |
1985年 | 25篇 |
1984年 | 33篇 |
1983年 | 15篇 |
1982年 | 15篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1974年 | 3篇 |
1959年 | 2篇 |
1951年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
V. F. Ivanov A. A. Nekrasov K. V. Tcheberiako A. V. Vannikov A. S. Posed'ko S. I. Lishik Yu. V. Trofimov 《Journal of the Society for Information Display》2003,11(1):11-14
Abstract— An all solid‐state photoelectrochromic element (PECE) was developed on the basis of electrochromic layers of WO3 and polyaniline with a layer of polymer electrolyte placed on a base of polyamidosulfoacid, in which a thin‐film CdSxSe1?x photoresistor was used as an electronic key. The dependence of the sensitometric characteristics of the PECE on the applied voltage was studied. 相似文献
12.
镍氢电池负极用低成本储氢合金的研究 总被引:1,自引:0,他引:1
研究了ABS型储氢合金在低Co含量条件下,随B组元替代元素Co,Al,Si等含量的变化对合金电化学性能的影响规律,同时研究了A组元中不同La/Ce比对合金电化学性能的影响情况。结果表明,随合金中Co含量的降低,合金的活化性能和放电容量得以改善,但合金的循环寿命下降也比较明显;在试验范围内,随Al元素的加入,合金的循环寿命得以改善,但材料的放电容量和活化性能均有所下降;随合金La/Ce比的降低,合金的放电容量略有下降,但其循环寿命和放电电压平台有较大提高。 相似文献
13.
14.
15.
The influence of an aggressive environment (0.6 M, aerated NaCl solution) on short fatigue crack initiation and growth behaviour has been studied. The study involved three major test series, namely: air fatigue, corrosion fatigue, and intermittent air fatigue/corrosion fatigue. The above tests carried out under fully reversed torsional loading conditions at a frequency of 5 Hz, showed that it was the non-metallic inclusions which took part in crack initiation resulting from debonding at metal matrix/inclusion interface and pitting of inclusions in both air and corrosove environments, respectively. Short fatigue crack growth results in these two environments obtained by using plastic replication technique, indicated a large effect of microstructure i.e. prior austenite grain boundaries. The stage/stages at which the environmental contribution was dominant has been discussed by considering the results achieved from intermittent tests. However, the mechanisms involved in corrosion fatigue short crack growth have also been described in the light of results obtained from futher investigations carried out by conducting corrosion fatigue tests under applied cathodic potential conditions and tests on hydrogen pre-charged specimens under air fatigue and uniaxial tension conditions. 相似文献
16.
钻井过程中硫化氢的处理工艺 总被引:1,自引:0,他引:1
目的:防止钻井过程中出现的硫化氢对人身安全和钻具造成危害。方法:分析氢脆破坏机理和处理硫化氢的化学原理。结果:提出了处理硫化氢的关键技术,并结合塔中162井的实钻经验,总结出了钻井过程中对硫化氢的几点认识。结论:提高泥浆pH值、加入除硫剂及提高泥浆密度等措施是钻井过程中处理硫化氢的关键技术,从而有利于富含硫化氢的灰岩、白云岩等裂缝性油气藏的钻井生产。 相似文献
17.
Christos C. Agrafiotis Chrysoula Pagkoura Souzana Lorentzou Margaritis Kostoglou Athanasios G. Konstandopoulos 《Catalysis Today》2007,127(1-4):265-277
The present work summarizes the recent activities of our laboratory in the field of solar-aided hydrogen production with structured monolithic solar reactors. This reactor concept, “transferred” from the well-known automobile exhaust catalytic after-treatment systems, employs ceramic supports optimized to absorb effectively solar radiation and develop sufficiently high temperatures, that are coated with active materials capable to perform/catalyze a variety of “solar-aided” reactions for the production of hydrogen such as water splitting or natural gas reforming. Our work evolves in an integrated approach starting from the synthesis of active powders tailored to particular hydrogen production reactions, their deposition upon porous absorbers, testing of relevant properties of merit such as thermomechanical stability and hydrogen yield and finally to the design, operation simulation and performance optimization of structured monolithic solar hydrogen production reactors. This approach, among other things, has culminated to the world's first closed, solar-thermochemical cycle in operation that is capable of continuous hydrogen production employing entirely renewable and abundant energy sources and raw materials – solar energy and water, respectively – without any CO2 emissions and holds, thus, a significant potential for large-scale, emissions-free hydrogen production, particularly for regions of the world that lack indigenous resources but are endowed with ample solar energy. 相似文献
18.
19.
Magnesiumandmagnesiumalloyshavebeenin vestigatedashydrogenstoragematerialsforseveralde cadesbecausefarmorehydrogenbyweightcanbestoredinthemthaninmostoftheothercurrentlyknownhydrogenstoragealloys .Moreover ,thehighnaturalabundanceofMg ,itslightmassandenviron mentalcompatibilitypotentiallymakemagnesiumoneofthemostprospectivecandidatesforfuturehydrogenstoragematerials .Unfortunately ,thepracticalappli cationofMganditsalloyshasbeenlimitedonlytocertainstoragedevicebecauseoftheirpoorhydriding dehydr… 相似文献
20.
膜分离法回收合成氨弛放气中氢气 总被引:1,自引:0,他引:1
介绍了膜分离的原理和应用。实践表明该方法具有效率高、流程简单、操作灵活容易、纯度高和收率高等优点。 相似文献