全文获取类型
收费全文 | 2184篇 |
免费 | 198篇 |
国内免费 | 152篇 |
专业分类
电工技术 | 166篇 |
综合类 | 219篇 |
化学工业 | 300篇 |
金属工艺 | 372篇 |
机械仪表 | 97篇 |
建筑科学 | 191篇 |
矿业工程 | 78篇 |
能源动力 | 67篇 |
轻工业 | 132篇 |
水利工程 | 52篇 |
石油天然气 | 70篇 |
武器工业 | 19篇 |
无线电 | 71篇 |
一般工业技术 | 149篇 |
冶金工业 | 397篇 |
原子能技术 | 8篇 |
自动化技术 | 146篇 |
出版年
2024年 | 7篇 |
2023年 | 40篇 |
2022年 | 71篇 |
2021年 | 68篇 |
2020年 | 94篇 |
2019年 | 65篇 |
2018年 | 66篇 |
2017年 | 91篇 |
2016年 | 96篇 |
2015年 | 95篇 |
2014年 | 141篇 |
2013年 | 138篇 |
2012年 | 160篇 |
2011年 | 162篇 |
2010年 | 116篇 |
2009年 | 147篇 |
2008年 | 87篇 |
2007年 | 115篇 |
2006年 | 126篇 |
2005年 | 106篇 |
2004年 | 73篇 |
2003年 | 71篇 |
2002年 | 72篇 |
2001年 | 76篇 |
2000年 | 48篇 |
1999年 | 34篇 |
1998年 | 24篇 |
1997年 | 24篇 |
1996年 | 16篇 |
1995年 | 19篇 |
1994年 | 23篇 |
1993年 | 8篇 |
1992年 | 16篇 |
1991年 | 9篇 |
1990年 | 10篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1979年 | 1篇 |
1975年 | 1篇 |
1965年 | 1篇 |
1962年 | 1篇 |
1959年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有2534条查询结果,搜索用时 15 毫秒
31.
32.
共振搅拌反应器及其振动计算 总被引:1,自引:0,他引:1
本文阐述了共振搅拌器的设计原理、应用及其优点,对管式反应釜内液体振动的固有频率、液面主振型及自由振动响应进行了计算。并对搅拌器的共振作了理论和实验研究以及对反应釜振幅、频率对搅拌效果的影响进行了讨论。 相似文献
33.
Natasja Leth Bergholt Ari Demirel Michael Pedersen Ming Ding Tue Wenzel Kragstrup Thomas Andersen Bent Winding Deleuran Casper Bindzus Foldager 《International journal of molecular sciences》2022,23(1)
Systemic Intermittent Hypoxic Therapy (IHT) relies on the adaptive response to hypoxic stress. We investigated allogenic bone-graft resorption in the lumbar spine in 48 mice. The mice were exposed to IHT for 1 week before surgery or 1 week after surgery and compared with controls after 1 and 4 weeks. Complete graft resorption was observed in 33–36% of the animals in the control group, but none in the preoperative IHT group. Increased bone-graft volume was demonstrated by micro-computed tomography in the preoperative IHT group after 1 week (p = 0.03) while a non-significant difference was observed after 4 weeks (p = 0.12). There were no significant differences in the postoperative IHT group. Increased concentration of immune cells was localized in the graft area, and more positive tartrate-resistant acid phosphatase (TRAP) staining was found in controls compared with IHT allogenic bone grafts. Systemic IHT resulted in a significant increase of the major osteoclast inhibitor osteoprotegerin as well as osteogenic and angiogenic regulators Tgfbr3, Fst3l, Wisp1, and Vegfd. Inflammatory cytokines and receptor activator of nuclear factor kappa-B ligand (RANKL) stimulators IL-6, IL-17a, IL-17f, and IL-23r increased after 1 and 4 weeks, and serum RANKL expression remained constant while Ccl3 and Ccl5 decreased. We conclude that the adaptive response to IHT activates numerous pathways leading to inhibition of osteoclastic activity and inhibition of allogenic bone-graft resorption. 相似文献
34.
由于软件错误出现的随机性,软件产品的缺陷是不可完全避免的,较好地处理软件缺陷是提高软件产品质量的关键.为了尽可能多地发现软件中存在的错误,提高软件质量,文章讨论了软件中较难被发现的间歇性缺陷,即并不是在软件的每次运行中都会出现的缺陷,介绍了软件中可能存在的一些较为常见的间歇性缺陷,分析了引起这些缺陷的原因,给出了处理间歇性缺陷的启发式规则,并就如何对这类缺陷写缺陷报告给出了一些建议. 相似文献
35.
蒋学广 《探矿工程(岩土钻掘工程)》2008,35(4):47-49
结合工程实例分析了大理经济开发区复合地基设计中主要强调承载力而导致较多建筑过量沉降的问题,提出了复合地基设计时应以变形控制为主,承载力仅作验算指标的设计思路。 相似文献
36.
Permanent magnet stirring (PMS) featuring low power dissipation and high-intensity magnetic field was investigated as a means of decreasing internal solidification defects. In this study, the magnetic Taylor number (Ta) was used to quantify the melt ?ow. Initial research of PMS involved a laboratory study of the solidification of Sn–20 wt-% Pb alloy. An industrial plant trial with continuously cast tire cord steel confirmed that PMS, in accord with the laboratory findings, produced an improvement in central cavities in the cast product. Moreover, it was established that PMS is an alternative method for reducing carbon macrosegregation in tire cord steel billets with different section sizes. It was also found that PMS (Ta?=?8.97?×?107) was more effective for improving central carbon macrosegregation of tire cord steel than electromagnetic stirring (Ta?=?6.33?×?107) due to the larger Ta related to the driven-flow intensity of the residual melt. 相似文献
37.
《Journal of Nuclear Science and Technology》2013,50(9):729-739
The experimental study was conducted to examine the applicability of boiling potassium two-phase flow to the blanket cooling of fusion power reactors. A high flux heater pin of 44mm heating length and 6.5mm O. D. with eight thermocouples of 0.5mm O. D. was inserted from the bottom of a vertical channel which was made of a 4m long, 14.9mm I.D. and 17.5mm O. D. stainless steel tube and placed in a D.C. magnet of 50cm long poles. The experimental conditions were the heat flux: 0~67W/cm2, the magnetic field strength: 0~1.8T, the Ar cover gas pressure: 1.0bar, the potassium level above heater: 1.8m, and the temperature of upper unheated section: 400°C. In the absence of magnetic field, boiling occurred intermittently, repeating the cycles between superheating with moderate temperature fluctuation and desuperheating with condensing shock pulses. When a weak magnetic field was applied, the temperature fluctuation was enhanced by natural convection, the incipient boiling superheat was reduced, and the boiling pattern became continuous. With increasing the magnetic field strength, the fluctuation was suppressed and the incipient boiling superheat increased but tended to level off around 1.5 T. Violent incipient boiling caused by a large superheat inherent in liquid metals was mitigated by magnetohydrodynamic interaction under a transverse magnetic field of 1.0T or larger, and subsequently followed by continuous saturation boiling with small fluctuation. No burn-out of the heater pin occurred in spite of symptom of dryout within the experimental range: q=67W/cm2 and B=1.5T. 相似文献
38.
Numerical Simulation of Linear Electromagnetic Stirring in Secondary Cooling Region of Slab Caster 总被引:2,自引:1,他引:2
SymbolList B———Magneticfluxdensity ,T ; B ———ConjugatedcomplexnumberofB ,T ; Bc———Magneticfluxdensityinboundaryproducedbycoilcurrent,T ; Bi———Magneticfluxdensityinboundaryproducedbyin nerinductioncurrent ,T ; F———Electromagneticforce ,N·m- 3; g———Gravitationalacceleration ,m·s- 2 ; I———Coilcurrent ,A ; j———Symbolusedcommonlyinelectricalnotation(=- 1) ; J———Inductioncurrentdensity ,A·m- 2 ; k———Turbulencekineticenergy ,m2·… 相似文献
39.
40.