全文获取类型
收费全文 | 1471篇 |
免费 | 48篇 |
专业分类
电工技术 | 8篇 |
综合类 | 7篇 |
化学工业 | 367篇 |
金属工艺 | 40篇 |
机械仪表 | 15篇 |
建筑科学 | 39篇 |
矿业工程 | 1篇 |
能源动力 | 14篇 |
轻工业 | 132篇 |
水利工程 | 7篇 |
无线电 | 133篇 |
一般工业技术 | 232篇 |
冶金工业 | 360篇 |
原子能技术 | 11篇 |
自动化技术 | 153篇 |
出版年
2023年 | 13篇 |
2021年 | 30篇 |
2020年 | 19篇 |
2019年 | 18篇 |
2018年 | 24篇 |
2017年 | 21篇 |
2016年 | 24篇 |
2015年 | 33篇 |
2014年 | 30篇 |
2013年 | 50篇 |
2012年 | 44篇 |
2011年 | 73篇 |
2010年 | 61篇 |
2009年 | 55篇 |
2008年 | 52篇 |
2007年 | 51篇 |
2006年 | 53篇 |
2005年 | 35篇 |
2004年 | 34篇 |
2003年 | 40篇 |
2002年 | 38篇 |
2001年 | 36篇 |
2000年 | 33篇 |
1999年 | 44篇 |
1998年 | 102篇 |
1997年 | 73篇 |
1996年 | 53篇 |
1995年 | 40篇 |
1994年 | 29篇 |
1993年 | 33篇 |
1992年 | 16篇 |
1991年 | 12篇 |
1990年 | 23篇 |
1989年 | 15篇 |
1988年 | 12篇 |
1987年 | 7篇 |
1986年 | 7篇 |
1985年 | 15篇 |
1984年 | 8篇 |
1983年 | 9篇 |
1982年 | 8篇 |
1981年 | 6篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1978年 | 10篇 |
1977年 | 21篇 |
1976年 | 22篇 |
1975年 | 12篇 |
1967年 | 4篇 |
1966年 | 7篇 |
排序方式: 共有1519条查询结果,搜索用时 15 毫秒
1.
2.
Matthias Siemon Olaf Riese Burkhard Forell Dominic Krnung Walter Klein‐Heßling 《火与材料》2019,43(5):497-513
In the context of industrial buildings and power plants, electrical installations and cable trays represent a main fuel load and a potential initial fire source due to possible short circuits or comparable malfunction. Furthermore, a fire can spread from one tray to additional trays mounted above and/or horizontally on one tray. Because of the high significance of cable fires, several research projects have been carried out, investigating the fire behaviour of cables from small‐scale tests, eg, the cone calorimeter, up to large‐scale tests, analysing complete cable tray constructions. The goal of the work presented in this paper is the extension of the knowledge regarding the influence of geometrical parameters like the packing density and tray distance on the burning behaviour and fire spread of cable tray installations. The results are considered, together with test results from the literature, to quantify the main physical parameters describing the burning behaviour. In a next step, the general applicability of these parameters as input data for the parametrization of the source term of numerical simulations is shown. The test results show that the burning behaviour and the fire spreading highly depend on the cable arrangement of the cables on the cable tray, in combination with other boundary conditions. By applying the results as input for a fire simulation, the mass loss rate is considered appropriately. 相似文献
3.
4.
5.
6.
7.
Biodegradation of monoaromatic hydrocarbons in aquifer columns amended with hydrogen peroxide and nitrate 总被引:1,自引:0,他引:1
The ability of indigenous microorganisms to degrade benzene, toluene, ethylbenzene and xylenes (BTEX) in laboratory scale flow-through aquifer columns was tested separately with hydrogen peroxide (110 mg/l) and nitrate (330 mg/l as NO3−) amendments to air-saturated influent nutrient solution. The continuous removal of individual components from all columns relative to the sterile controls provided evidence for biodegradation. In the presence of hydrogen peroxide, the indigeneous microorganisms degraded benzene and toluene (> 95%), meta- plus para-xylene (80%) and ortho-xylene (70%). Nitrate addition resulted in 90% removal of toluene and 25% removal of ortho-xylene. However, benzene, ethylbenzene, meta- and para-xylene concentrations were not significantly reduced after 42 days of operation. Following this experiment, low dissolved oxygen (< 1 mg/l) conditions were initiated with the nitrate-amended column influent in order to mimic contaminated groundwater conditions distal from a nutrient injection well. Toluene continued to be effectively degraded (> 90%), and more than 25% of the benzene, 40% of the ethylbenzene, 50% of the meta- plus para-xylenes and 60% of the ortho-xylene were removed after several months of operation. 相似文献
8.
J.-P. Han S.M. Koo E.M. Vogel E.P. Gusev C. DEmic C.A. Richter J.S. Suehle 《Microelectronics Reliability》2005,45(5-6):783
Anomalous threshold voltage roll-up behavior, commonly referred as reverse short channel effect (RSCE), has been observed in high-k (HfO2 on SiON buffer, Al2O3 on SiON buffer) gated submicron nMOSFETs, while the SiO2 or SiON control samples show normal short channel effect (SCE) behavior. The possible causes such as inhomogeneous channel doping profile and gate oxide thickness variation near S/D ends have been ruled out. The results indicate that interface trap density that dependents on channel length is the main cause of the RSCE observed here. In addition, oxide charge also plays a role. 相似文献
9.
10.
The authors have implemented chirped distributed feedback (DFB) grating lasers with phase shifts [λ/8, 2λ/8 and 3λ/8] distributed continuously over various axial distances, using their recently proposed method for producing bent optical waveguides. The singlemode stability of the lasers with distributed phase shifts was found to be considerably higher than for lasers with abrupt phase shifts 相似文献