全文获取类型
收费全文 | 1992篇 |
免费 | 35篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 20篇 |
化学工业 | 326篇 |
金属工艺 | 105篇 |
机械仪表 | 74篇 |
建筑科学 | 39篇 |
矿业工程 | 35篇 |
能源动力 | 24篇 |
轻工业 | 158篇 |
水利工程 | 97篇 |
石油天然气 | 230篇 |
无线电 | 101篇 |
一般工业技术 | 371篇 |
冶金工业 | 232篇 |
原子能技术 | 40篇 |
自动化技术 | 177篇 |
出版年
2018年 | 23篇 |
2017年 | 23篇 |
2016年 | 28篇 |
2014年 | 19篇 |
2013年 | 166篇 |
2012年 | 54篇 |
2011年 | 75篇 |
2010年 | 45篇 |
2009年 | 34篇 |
2008年 | 43篇 |
2007年 | 29篇 |
2006年 | 36篇 |
2004年 | 19篇 |
2003年 | 21篇 |
2002年 | 23篇 |
2001年 | 32篇 |
2000年 | 22篇 |
1999年 | 30篇 |
1998年 | 67篇 |
1997年 | 47篇 |
1996年 | 36篇 |
1995年 | 19篇 |
1994年 | 28篇 |
1993年 | 40篇 |
1992年 | 29篇 |
1991年 | 39篇 |
1990年 | 34篇 |
1989年 | 44篇 |
1988年 | 37篇 |
1987年 | 30篇 |
1986年 | 23篇 |
1985年 | 32篇 |
1984年 | 44篇 |
1982年 | 21篇 |
1981年 | 34篇 |
1980年 | 36篇 |
1979年 | 39篇 |
1978年 | 45篇 |
1977年 | 43篇 |
1976年 | 44篇 |
1975年 | 48篇 |
1974年 | 51篇 |
1973年 | 38篇 |
1972年 | 28篇 |
1971年 | 28篇 |
1970年 | 34篇 |
1969年 | 30篇 |
1968年 | 23篇 |
1967年 | 20篇 |
1965年 | 19篇 |
排序方式: 共有2029条查询结果,搜索用时 31 毫秒
1.
2.
The article established the regularities of change of the physicomechanical characteristics and strength of glass textolites in single and repeated thermal loading. It shows that under multiple loading the intense loss of strength of the investigated materials is due to increased porosity on account of the large number of microcracks appearing in the structure. A correlation is obtained between the elastic and strength characteristics and porosity in dependence on the temperature of multiple heating which in the first approximation is described by a polynomial of second degree with respect to temperature, multiplied by the reciprocal of porosity.Translated from Problemy Prochnosti, No. 6, pp. 53–58, June, 1991. 相似文献
3.
Ér. V. Kal’yanov 《Technical Physics Letters》2007,33(6):451-453
A new simple model of a system with chaotic dynamics, based on the equations of bistable systems, is considered. The possibility of converting harmonic signals into chaotic oscillations, which represent intermittent irregular and switching quasi-regular motions, is demonstrated by numerical methods. The mechanism of chaotization is analyzed using the results of numerical calculations. 相似文献
4.
Thermal treatment applied in association with a biological system allows for a significant reduction in excess sludge production (approximately 50%). In general, heat treatment is described as a sludge disintegration technique. This paper offers a thorough study on the impact of heat treatment, at temperatures below 100 degrees C, on the solubilisation of the sludge COD and its biodegradability. Discontinuous heating experiments were performed on activated and digested sludge. At all temperatures tested the released COD for digested sludge was systematically higher than that for activated sludge (15 and 40%, respectively, at 95 degrees C for 40 min of contact time). For the first 30 min, a 1st order kinetic, with respect to the residual COD, was systematically found. In the range of 40-95 degrees C, digested sludge had a lower activation energy than activated sludge (26 kcal/mol compared to 70-160 kcal/mol). COD solubilisation is thus more positively influenced by temperature in the case of activated sludge. This may be due to the significant difference in the ratio of protein/carbohydrate in digested and activated sludge (1-5 and 0.2-0.7, respectively). The increase in the COD/TKN ratio in the solubilised fraction after thermal treatment of activated sludge suggests a preferential solubilisation of proteins over carbohydrates. Respirometric tests performed on the solubilised COD showed that whatever the sludge origin, only 40-50% of released COD is biodegradable at a conventional hydraulic retention time (i.e., 24 h). Hence, heat treatment would act more through organic matter solubilisation rather than by a biodegradability increase. 相似文献
5.
A theoretical model for electrons escaping a quantum well under the influence of an applied electric field is developed. Both the thermionic emission and tunneling components of the currents are calculated, taking into account the proper partitioning between the two currents. The group velocity for a nonuniform electron distribution within the quantum well, which is a function of position and energy, and the continuous energy dependence of the quantum well density of states is considered. A comparison between this model and previously reported experimental results are made which demonstrates excellent agreement 相似文献
6.
7.
G. T. Vigant A. B. Énglin N. N. Zakharova I. V. Klimyuk 《Chemistry and Technology of Fuels and Oils》1991,27(5):244-248
Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 5, 11–13, May, 1991. 相似文献
8.
The properties of glasses of the lithium-aluminoborosilicate system were investigated, namely, the density, spreadability, thermal expansion, and nature of crystallized phases at various temperatures. A crystal-optical analysis was conducted. The glasses were used to prepare abrasive compositions. Their strength properties were studied as a function of the composition of the glass binder and the regime of heat treatment.Translated from Steklo i Keramika, No. 3, pp. 27–30, March, 1996. 相似文献
9.
The fluctuations observed by recording the picosecond pulses of a mode-locked laser with a synchroscan streak camera are due to the laser jitter and to the variations of the zero crossing of the synchronization. By means of a simple model, it is shown that the dispersions measured when the synchronization is generated from the mode-locker oscillator reflect the instantaneous time phase fluctuations of this oscillator. From the study of the experimental recordings with methods of time series analysis it results that the phase noise of the electronic oscillator is consistent with an underlying low-dimensional strange attractor. 相似文献
10.
Éntin S. V. Anzheurov N. M. Krasovitskii Yu. V. Panova O. A. Shcheglova L. I. 《Refractories and Industrial Ceramics》2003,44(3):194-198
An experimental setup for studying filter-assisted dust collection is described. The role of various factors — hydraulic resistance, filtering velocity, dust concentration, pressure drop, efficiency of recovery — in the performance of filters intended for use in the production of refractory materials is considered. The dust removal method was tested under industrial conditions at the Semilukskii Refractory Plant and can be recommended for wider use in different branches of industry. 相似文献