首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   79273篇
  免费   5743篇
  国内免费   3154篇
电工技术   4629篇
技术理论   4篇
综合类   4407篇
化学工业   12645篇
金属工艺   4629篇
机械仪表   5520篇
建筑科学   4859篇
矿业工程   1617篇
能源动力   1823篇
轻工业   4775篇
水利工程   1567篇
石油天然气   3484篇
武器工业   495篇
无线电   9655篇
一般工业技术   12730篇
冶金工业   4445篇
原子能技术   1185篇
自动化技术   9701篇
  2024年   245篇
  2023年   927篇
  2022年   1959篇
  2021年   2803篇
  2020年   2071篇
  2019年   2046篇
  2018年   2695篇
  2017年   2956篇
  2016年   3153篇
  2015年   3214篇
  2014年   4056篇
  2013年   5043篇
  2012年   5152篇
  2011年   5453篇
  2010年   5031篇
  2009年   4875篇
  2008年   4796篇
  2007年   4467篇
  2006年   4206篇
  2005年   3395篇
  2004年   2411篇
  2003年   2135篇
  2002年   2411篇
  2001年   2027篇
  2000年   1972篇
  1999年   1658篇
  1998年   1397篇
  1997年   1223篇
  1996年   844篇
  1995年   711篇
  1994年   607篇
  1993年   462篇
  1992年   341篇
  1991年   274篇
  1990年   210篇
  1989年   156篇
  1988年   137篇
  1987年   78篇
  1986年   63篇
  1985年   60篇
  1984年   46篇
  1983年   27篇
  1982年   30篇
  1981年   29篇
  1980年   34篇
  1979年   24篇
  1978年   22篇
  1976年   29篇
  1975年   16篇
  1969年   23篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
空间分析研究   总被引:1,自引:0,他引:1  
熊旭平  郭云开  陈进 《山西建筑》2007,33(5):353-354
提出了空间分析的概念及其功能实现的四个层次,分析了基于GIS空间分析的现状,并对以神经网络、进化计算和人工生命为主要代表的智能计算工具的特点、功能、适用领域进行了阐述,指出它们将为未来空间分析的发展提供良好的前景。  相似文献   
92.
93.
A range of refractories is presented for handling steel outside a furnace, which are produced by the Borovichi Refractories Corporation. The refractory characteristics and working features are given. Translated from Novye Ogneupory, No. 9, pp. 29–35, September, 2008.  相似文献   
94.
Technology is developed for preparing refractory components made of partially stabilized zirconium dioxide using an isostatic compaction press. Technology is provided for manufacturing dispensing nozzles using combined and separately stabilized zirconium dioxide, and also indices of the refractories obtained and imported materials are compared. __________ Translated from Novye Ogneupory, No. 3, pp. 127–131, March 2008.  相似文献   
95.
Compositions have been developed for nonshrinking vibrocast thermally insulating light refractory concretes with densities of 1.0, 1.3, 1.5, and 1.8 g/cm3 for temperatures of use up to 1400°C. The structure and properties have been examined for the concrete of density 1.3 g/cm3. __________ Translated from Novye Ogneupory, No. 4, pp. 29–32, April, 2008.  相似文献   
96.
Methods are proposed for designing interpolation models for the preliminary determination and subsequent forecasting of general and fractional breakthrough coefficients for dust used with granular filters, as employed in energy-saving and high-performance dust trapping from technological gases and ventilation discharges in refractory production. The models are supplied with nomograms, which makes them widely suitable for experts working in environmental protection at refractory-producing organizations. The main factors are identified that influence the performance. The results are of interest to experts in related areas of industry such as building materials and engineering ceramics and so on. Translated from Novye Ogneupory, No. 4, pp. 64–67, April, 2008.  相似文献   
97.
In the OAO Borovich Refractory Combine production has been assimilated for a complete set of refractories for continuous steel casting, i.e. from a pipe for protecting a stream of metal to a submerged nozzle. In technical and life characteristics the products correspond to that of world analogs, they provide accident free steel pouring, make it possible to reduce the specific consumption of refractories per ton of steel, to increase CBCM productivity, to reduce billet scrap, and to reduce steel cost. Translated from Novye Ogneupory, No. 8, pp. 4–9, August 2008.  相似文献   
98.
The processes of phase formation in the Na2CO3-TiO2 and Na2CO3-TiO2-Nd2O3 systems are investigated in the temperature range 600–900°C. The high-temperature solid-phase reactions underlying the process of formation of complex oxide NaNdTiO4 are studied. It is established that the synthesis of the NaNdTiO4 compound occurs through the reaction of the intermediate product Na8Ti5O14 with neodymium oxide in the temperature range 720–780°C. The optimum method is proposed for synthesizing NaNdTiO4, which makes it possible to reduce the temperature of the synthesis, to avoid the formation of impurities, and to obtain the product in a finely dispersed state.  相似文献   
99.
The aggregate stability of submicron and nanosized ZrO2 aqueous sols of different origins and different dispersities at pH 3–10 in the KCl concentration range 10?3–10?1 M is investigated by flow ultramicroscopy and photometry. The results obtained are analyzed in the framework of the extended Derjaguin-Landau-Verwey-Overbeek theory and the Muller-Martynov theory of reversible aggregation. The extension of boundary layers of water near the surface of the ZrO2 particles is estimated.  相似文献   
100.
The distribution and structure of tellurium nanoclusters synthesized in crystal channels of the porous silica ZSM-11 are investigated using the maximum-entropy method and the Rietveld analysis. It is shown that the intercalated tellurium atoms are arranged in channels of the ZSM-11 zeolite not randomly but in the form of scraps of infinite chains similar to those observed in massive tellurium. The distances between the nearest neighbor tellurium atoms vary in the range 2.53(4)–2.70(3) ?. The clusters Te4 are formed at the intersections of channels in the structure. These clusters have the form of distorted tetrahedra in which the tellurium atoms are separated by distances of 2.53(4) and 2.90(4) ?. Original Russian Text ? A.E. Lapshin, Yu.F. Shepelev, Yu.I. Smolin, E.A. Vasil’eva, 2008, published in Fizika i Khimiya Stekla.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号