全文获取类型
收费全文 | 427724篇 |
免费 | 5921篇 |
国内免费 | 1277篇 |
专业分类
电工技术 | 6956篇 |
综合类 | 327篇 |
化学工业 | 66603篇 |
金属工艺 | 18059篇 |
机械仪表 | 13841篇 |
建筑科学 | 9876篇 |
矿业工程 | 2410篇 |
能源动力 | 10389篇 |
轻工业 | 37399篇 |
水利工程 | 4788篇 |
石油天然气 | 10504篇 |
武器工业 | 17篇 |
无线电 | 49364篇 |
一般工业技术 | 86012篇 |
冶金工业 | 73408篇 |
原子能技术 | 10340篇 |
自动化技术 | 34629篇 |
出版年
2021年 | 3907篇 |
2020年 | 2958篇 |
2019年 | 3637篇 |
2018年 | 6054篇 |
2017年 | 6164篇 |
2016年 | 6818篇 |
2015年 | 4314篇 |
2014年 | 7321篇 |
2013年 | 19000篇 |
2012年 | 12048篇 |
2011年 | 16213篇 |
2010年 | 12643篇 |
2009年 | 14055篇 |
2008年 | 14419篇 |
2007年 | 14062篇 |
2006年 | 12654篇 |
2005年 | 11467篇 |
2004年 | 10992篇 |
2003年 | 10745篇 |
2002年 | 10211篇 |
2001年 | 10553篇 |
2000年 | 9709篇 |
1999年 | 10022篇 |
1998年 | 23044篇 |
1997年 | 16214篇 |
1996年 | 12279篇 |
1995年 | 9371篇 |
1994年 | 8194篇 |
1993年 | 8170篇 |
1992年 | 6169篇 |
1991年 | 5984篇 |
1990年 | 5870篇 |
1989年 | 5615篇 |
1988年 | 5502篇 |
1987年 | 4731篇 |
1986年 | 4687篇 |
1985年 | 5377篇 |
1984年 | 4929篇 |
1983年 | 4611篇 |
1982年 | 4265篇 |
1981年 | 4514篇 |
1980年 | 4206篇 |
1979年 | 4252篇 |
1978年 | 4240篇 |
1977年 | 4552篇 |
1976年 | 5763篇 |
1975年 | 3788篇 |
1974年 | 3746篇 |
1973年 | 3858篇 |
1972年 | 3261篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
The performance of two distributed channel assignment algorithms which use coexistence etiquettes for point to point links are considered by the authors. It has been found that selecting channels prior to transmission at the transmitter as opposed to the receiver, supports greater offered traffic with the additional advantage of a less complex protocol 相似文献
973.
A. Benati M.A. Butturi C. Capperdoni M.C. Carotta G. Martinelli M. Merli L. Passari G. Sartori R. Van Steenwinkel G.M. Youssef 《Solar Energy Materials & Solar Cells》1996,43(2):183
The newly developed ingot growing techniques, as the three-grain and the columnar multigrain ingot processes, are now offering the possibility of slicing thinner wafers (≤ 100 μm). In this paper we present the results obtained on p type large area (≥ 100 cm2) and 100 μm thick wafers by using both conventional and reverse cell manufacturing technologies.The conventional cells are provided with aluminium or boron BSF plus screen-printed silver mirror or a silver-aluminium net; the reverse cells have a FSF and the deep back junction completely covered by a screen-printed or CVD silver layer.The constructing parameters have been chosen on the base of one and two dimensions modeling and both raw material and devices have been completely characterized.This work shows that very thin wafers do not introduce serious problems for the conventional manufacturing of solar cells. The efficiencies of the normal and of the reverse cells are found to be comparable and are of the same order than those of thicker cells, however at a significant lower cost. The main obtained result has to be related to the demonstration of a cell manufacturing feasibility starting from very thin wafers. 相似文献
974.
Selhi H. Christopoulos C. Howe A.F. Hui S.Y.R. 《Energy Conversion, IEEE Transaction on》1996,11(2):287-297
The simulation of a complete induction motor drive is presented. The entire network is modelled using the transmission-line modelling (TLM) technique. The network is split into three sections which are solved independently and are joined together by link transmission-line models. Advantages of this approach are the explicit nature of the algorithm which remains unaltered irrespective of the network topology, unconditional stability, and straightforward modelling of switching elements. Results are presented for a complete drive which illustrate the capabilities and flexibility of the simulation technique 相似文献
975.
976.
977.
V. I. Filatov 《Measurement Techniques》1996,39(9):943-945
Hydrodynamic errors are analyzed theoretically. The results of experimental investigations of Filatov flowmeters in which
these errors are eliminated, are presented.
Translated from Izmeritel'naya Tekhnika, No. 9, pp. 36–37, September, 1996. 相似文献
978.
In this work we investigated the mechanism of the electrochemical intercalation reactions in rf sputtered nickel oxide thin films electrodes by two techniques: mechanical stress change measurements by means of an optical technique and mass changes using an electrochemical quartz microbalance (EQCM). The experiments were performed in alkaline electrolytes containing cations of the first column of the periodic table. Reversible mass and volume changes were observed. In order to explain these experimental results, an exchange reaction is proposed, in which the oxidation process is accompanied by the deinteractional of a relative large number of “light” cations, simultaneously with the intercalation of a smaller number of heaviest cations. 相似文献
979.
V. I. Bergel'son D. V. Pomazkin 《Journal of Engineering Physics and Thermophysics》1994,66(2):133-136
A heat wave propagating in a locally inhomogeneous medium containing elongated channels with elevated thermal diffusivity is considered.Institute of the Dynamics of Geospheres, Russian Academy of Sciences, Moscow. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 66, No. 2, pp. 151–154, February, 1994. 相似文献
980.
A simple and accurate measurement of intraabdominal pressure is essential to predict a successful closure of defects in omphalocele and gastroschisis. Intravesical pressure (IVP) is a close estimation of intraabdominal pressure and can be measured safely by placing a catheter in the urinary bladder during surgery. Three neonates with gastroschisis and four with omphalocele were studied. Pressure-related complications such as ascites leakage, ventral hernia, impaired venous return of the lower extremities, and oliguria developed only in the patients with IVP > 20 mmHg after fascial closure. Prolonged hospitalization, ventilation support and intensive care were required for these patients. 相似文献