全文获取类型
收费全文 | 8374篇 |
免费 | 511篇 |
国内免费 | 653篇 |
专业分类
电工技术 | 78篇 |
综合类 | 507篇 |
化学工业 | 1684篇 |
金属工艺 | 1282篇 |
机械仪表 | 210篇 |
建筑科学 | 844篇 |
矿业工程 | 126篇 |
能源动力 | 292篇 |
轻工业 | 78篇 |
水利工程 | 171篇 |
石油天然气 | 2851篇 |
武器工业 | 19篇 |
无线电 | 61篇 |
一般工业技术 | 895篇 |
冶金工业 | 276篇 |
原子能技术 | 83篇 |
自动化技术 | 81篇 |
出版年
2024年 | 11篇 |
2023年 | 80篇 |
2022年 | 180篇 |
2021年 | 209篇 |
2020年 | 244篇 |
2019年 | 211篇 |
2018年 | 219篇 |
2017年 | 202篇 |
2016年 | 271篇 |
2015年 | 262篇 |
2014年 | 425篇 |
2013年 | 516篇 |
2012年 | 466篇 |
2011年 | 516篇 |
2010年 | 430篇 |
2009年 | 434篇 |
2008年 | 418篇 |
2007年 | 497篇 |
2006年 | 527篇 |
2005年 | 490篇 |
2004年 | 475篇 |
2003年 | 461篇 |
2002年 | 363篇 |
2001年 | 319篇 |
2000年 | 268篇 |
1999年 | 218篇 |
1998年 | 186篇 |
1997年 | 152篇 |
1996年 | 108篇 |
1995年 | 83篇 |
1994年 | 73篇 |
1993年 | 45篇 |
1992年 | 40篇 |
1991年 | 29篇 |
1990年 | 34篇 |
1989年 | 30篇 |
1988年 | 15篇 |
1987年 | 7篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 5篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1973年 | 1篇 |
1951年 | 2篇 |
排序方式: 共有9538条查询结果,搜索用时 15 毫秒
81.
用自制的旋臂式磨蚀实验仪,研究了5种高密度聚乙烯和1种顺丁橡胶改性的高密度聚乙烯,在铁尾矿和铁精矿浆体中的耐磨蚀性。耐磨蚀性最差的是HDPE2200J,耐磨蚀性较差的是HDPE6300M;HDPE5000s,6098和2480的耐磨蚀性较好;HDPE/cis-BR的耐磨蚀性最好。 相似文献
82.
本文总结了冷轧带肋钢筋在福州地区的应用情况,对现浇砼板裂缝现象进行现场调查,并探究其裂缝发生的机理,最后对高强带肋钢筋在砼楼板中的应用前景提出有益的建议和展望 相似文献
83.
Fluid catalytic cracking (FCC) is one of the most complex processes in the petroleum industry. The large degree of uncertainty in the kinetics of the cracking reactions and catalyst deactivation by coke deposition in the riser reactor are among several factors that contribute to the process complexity. The model developed by the authors (Ali and Rohani, 1995) is used lo investigate the effect of the three-lumped kinetic scheme (Weekman and Nace, 1970) and the four-lumped scheme (Lee ct ah, 1989) on the model predictability and reliability. The effect of changes in the catalyst circulation rate, gas oil feed rate, and oxygen feed concentration on various process variables is compared. It is shown that the three-lumped kinetic scheme, despite its extensive use in the literature (McFarlane et ah, 1993; Elnashaie and Elshishini, 1993; Theologos and Markatos, 1993; Arandes and de Lasa, 1992; Lopez-lsunza and Ruiz-Martinez, 1991), leads to erroneous results and should not be used in the dynamic simulation of the FCC units, 相似文献
84.
85.
86.
ZhangXiaojing QinRuyi LiuJinlong 《中国炼油与石油化工》2003,(4):31-35
This article refers to the procedure for selection, evaluation and development of the LADS-D desorption agent associated with the LADS-A adsorbent used in the non-hydroprocessing adsorptive desulfurization (LADS) process for FCC naphtha developed by LPEC Refining Research Institute. The LADS-D desorption agent can effectively remove the sulfides adsorbed on the LADS-A adsorbent. The saturated LADS-A adsorbent can be instantly regenerated by the LADS-D desorption agent to recover its adsorption activity. The LADS-D desorption agent can not only effectively remove all impurities adsorbed on the adsorbent, but also has strong ability to dissolve the impurities to keep a stable desorption efficiency of adsorbent to be basically commensurate with fresh adsorbent after extended use. 相似文献
87.
88.
Intergranular stress corrosion cracking(ISCC) of α-brass in neutral Mattsson's solutionwas found to be controlled by an unusual"W"-shaped galvanic cell whose cathode is thegrain boundary oxide film (G.B.0. film) andsurface film and the anode is fresh metal atthe cracked tip on both sides of the G.B.0.film. Redox reactions involved in the cellhave been proposed here. According to thismdel, initidtion of ISCC is caused by therupturing of surface film along grain boundaries,thus forming a galvanic cell. Propagation ofISCC resulted from alternate advances of G.B.0.film and dissolution on both sides of G.B.0.film caused by the effect of electrochemicalreaction. This work developed an effective approachto investigate the embrittlement process atthe tip of the crack, by increasing the lengthof the embrittlement region through constantstrain test and distinguishing the morphologyand the nature of the corrosion products byoptical microscopy and scanning electronmicroscopy (SEH). 相似文献
89.
90.
Stress corrosion cracking (SCC) of α-brass in ammonia solution was studied under mode III loading. The results showed that SCC occurred on the principal stress planes where shear stresses are zero. No SCC occurred on the maximum shear stress plane. Ammonia concentration affected fracture behaviour. When the concentration was low, many cracks with spacing of 10–150 μm were found on 45 ° planes, i.e., the principal stress planes. When the concentration was high, the cracks on 45 ° planes were not clearly visible because of serious general corrosion. 相似文献