全文获取类型
收费全文 | 482954篇 |
免费 | 5597篇 |
国内免费 | 1756篇 |
专业分类
电工技术 | 8283篇 |
综合类 | 2626篇 |
化学工业 | 70447篇 |
金属工艺 | 20944篇 |
机械仪表 | 16440篇 |
建筑科学 | 10435篇 |
矿业工程 | 2696篇 |
能源动力 | 12599篇 |
轻工业 | 31819篇 |
水利工程 | 5454篇 |
石油天然气 | 8234篇 |
武器工业 | 17篇 |
无线电 | 58005篇 |
一般工业技术 | 97903篇 |
冶金工业 | 77422篇 |
原子能技术 | 9396篇 |
自动化技术 | 57587篇 |
出版年
2022年 | 2549篇 |
2021年 | 3886篇 |
2020年 | 2944篇 |
2019年 | 3805篇 |
2018年 | 20223篇 |
2017年 | 19167篇 |
2016年 | 16425篇 |
2015年 | 4884篇 |
2014年 | 7337篇 |
2013年 | 20193篇 |
2012年 | 14334篇 |
2011年 | 24144篇 |
2010年 | 19963篇 |
2009年 | 18960篇 |
2008年 | 20480篇 |
2007年 | 21184篇 |
2006年 | 12517篇 |
2005年 | 12224篇 |
2004年 | 11521篇 |
2003年 | 11497篇 |
2002年 | 10326篇 |
2001年 | 9820篇 |
2000年 | 9299篇 |
1999年 | 9573篇 |
1998年 | 24393篇 |
1997年 | 16744篇 |
1996年 | 12844篇 |
1995年 | 9526篇 |
1994年 | 8382篇 |
1993年 | 8396篇 |
1992年 | 6070篇 |
1991年 | 5719篇 |
1990年 | 5679篇 |
1989年 | 5318篇 |
1988年 | 5054篇 |
1987年 | 4422篇 |
1986年 | 4303篇 |
1985年 | 4813篇 |
1984年 | 4424篇 |
1983年 | 4000篇 |
1982年 | 3654篇 |
1981年 | 3733篇 |
1980年 | 3432篇 |
1979年 | 3329篇 |
1978年 | 3335篇 |
1977年 | 3752篇 |
1976年 | 4862篇 |
1975年 | 2853篇 |
1974年 | 2665篇 |
1973年 | 2731篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
Yu. F. Patrakov E. S. Pavlusha N. I. Fedorova Yu. A. Strizhakova 《Solid Fuel Chemistry》2008,42(1):10-13
The results of the thermal solution of oil shale in benzene in a flow unit under supercritical conditions are reported. It was found that the conversion of shale organic matter into liquid products increased by a factor of 2.5 with an increase in the solvent pressure from 5 to 15 MPa. 相似文献
182.
D. Ballutaud F. Jomard T. Kociniewski E. Rzepka H. Girard S. Saada 《Diamond and Related Materials》2008,17(4-5):451-456
Hot filament and microwave plasma CVD micro- nanocrystalline diamond films are analysed by visible and ultra-violet excitation source Raman spectroscopy. The sample grain size varies from 20 nm to 2 μm. The hydrogen concentration in samples is measured by SIMS and compared to the grain size, and to the ratio of sp2 carbon bonds determined by Raman spectroscopy from the 1332 cm− 1 diamond peak and the sp2 1550 cm− 1 G band. Hydrogen concentration appears to be proportional to the sp2 bonds ratio. The 3000 cm− 1 CHx stretching mode band intensity observed on the Raman spectra is decreasing with the G band intensity. Thermal annealing modifies the sp2 phase structure and concentration, as hydrogen outdiffuses. 相似文献
183.
A model of contact thermolysis was constructed based on a combined set of equations for heat transfer from a magmatic intrusion to a coal bed and the kinetics of thermal coal conversion. This model was illustrated by the generation of petroleum hydrocarbons deep in the earth by the thermolysis of the sapropelic matter of boghead. 相似文献
184.
Ottavia Colombo Simona Villani Giovanna Pinelli Claudia Trentani Maurizia Baldi Orazio Tomarchio Anna Tagliabue 《Nutrition journal》2008,7(1):5
Background
Excess body fat is a major risk factor for disease primarily due to its endocrine activity. In recent years several criteria have been introduced to evaluate this factor. Nevertheless, treatment need is currently assessed only on the basis of an individual's Body Mass Index (BMI), calculated as body weight (in kg) divided by height in m2. The aim of our study was to determine whether application of the BMI, compared to adiposity-based criteria, results in underestimation of the number of subjects needing lifestyle intervention. 相似文献185.
P. S. Gordienko V. A. Kolzunov L. G. Zorina T. A. Kaidalova S. B. Yarusova 《Theoretical Foundations of Chemical Engineering》2008,42(5):680-683
The possibility of processing fluorine-containing wastes of fluorite ore, which include fluorite, calcite, quartz, and anorthite, has been investigated. A manufacturing flow chart of the complex processing of the ore waste materials with the production of sodium fluoride, alumina, soda ash, and raw materials suitable for the production of Portland cement and wollastonite is suggested. 相似文献
186.
V. M. Vorotyntsev G. M. Mochalov M. A. Kolotilova S. S. Suvorov A. V. Koroleva A. Yu. Sharov 《Theoretical Foundations of Chemical Engineering》2008,42(2):197-202
The results of theoretical and experimental studies for the kinetics of separating dichlorosilane from a mixture of volatile chlorosilanes and ultrapurifying the dichlorosilane concentrate by batch distillation are reported. A mathematical model of the process is proposed. It is shown that the model and computational algorithm adequately describe both processes. The obtained experimental and theoretical data made it possible to design a concentration and ultrapurification process with a maximal productivity at a specified product purity. 相似文献
187.
Digant Gupta Christopher G Lis Sadie L Dahlk Jessica King Pankaj G Vashi James F Grutsch Carolyn A Lammersfeld 《Nutrition journal》2008,7(1):19
Background
Bioelectrical Impedance (BIA) derived phase angle is increasingly being used as an objective indicator of nutritional status in advanced cancer. Subjective Global Assessment (SGA) is a subjective method of nutritional status. The objective of this study was to investigate the association between BIA derived phase angle and SGA in advanced colorectal cancer. 相似文献188.
E. P. Velikhov N. N. Ponomarev-Stepnoi V. G. Volkov G. G. Gorodetskii Yu. A. Zverkov O. P. Ivanov S. M. Koltyshev V. D. Muzrukova S. G. Semenov V. E. Stepanov A. V. Chesnokov A. D. Shisha 《Atomic Energy》2007,102(5):375-381
This article is devoted to work done in 2002–2006 as part of the unified project Reabilitatsiya to rehabilitate radiation
hazardous objects and sections of the radioactively contaminated territory of the Russian Science Center Kurchatov Institute.
The main objects of the rehabilitation work were old storage sites built for radioactive wastes on the territory of the Institute
when military and civilian nuclear technologies were under development. The structural features of the storage sites, including
the volumes and characteristics of the wastes stored, are presented. The salient aspects of the disposal sites, taken into
account during the rehabilitation work, are discussed. The organization of the rehabilitation operations and the sequence
in which they are performed, the special features of the technical design solutions used, the technological methods, and ways
for conducting the work are described.
__________
Translated from Atomnaya énergiya, Vol. 102, No. 5, pp. 300–306, May, 2007. 相似文献
189.
A new torque estimator for switched reluctance motor (SRM) drives based on 2-D rotary regression analysis is presented in this paper. The proposed torque estimator is composed of a bicubic regressive polynomial as a function of rotor position and input current. The regressive coefficients can be computed offline or online from the torque characteristics acquired either experimentally or from numerical computation. Furthermore, a torque estimation method by taking mutual coupling into consideration is proposed. It can be seen that the estimated and experimentally obtained self-coupling and mutual-coupling torque characteristics are in good agreement with each other. In addition, the dynamic torque waveforms with and without the mutual coupling, estimated by the proposed estimator, are found to be virtually the same as those obtained from the bicubic spline interpolation for SRM drives with single-pulse voltage, hysteresis current chopping, as well as with voltage pulse width modulation control. The success of all the case studies being reported is a good validation of the usefulness and accuracy of the proposed real-time torque estimator that, as described in this paper, can be used to quickly estimate the instantaneous output torque of SRM drives. 相似文献
190.
The authors comments on the claim of Takahashi et al. that the distribution model, utilizing the mixture of Gaussian distributions, for the local critical current density of superconducting materials they proposed is a new idea. The authors points out the the method have been known since 1886. 相似文献