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   273683篇
  免费   4961篇
  国内免费   1832篇
电工技术   5500篇
技术理论   5篇
综合类   1175篇
化学工业   44525篇
金属工艺   11229篇
机械仪表   7989篇
建筑科学   6957篇
矿业工程   1691篇
能源动力   5829篇
轻工业   28199篇
水利工程   3037篇
石油天然气   6037篇
武器工业   245篇
无线电   28355篇
一般工业技术   51257篇
冶金工业   50129篇
原子能技术   5678篇
自动化技术   22639篇
  2021年   2801篇
  2020年   1982篇
  2019年   2470篇
  2018年   3950篇
  2017年   3908篇
  2016年   4222篇
  2015年   3234篇
  2014年   5120篇
  2013年   12416篇
  2012年   8495篇
  2011年   10859篇
  2010年   8699篇
  2009年   9184篇
  2008年   9999篇
  2007年   10051篇
  2006年   8748篇
  2005年   7631篇
  2004年   6917篇
  2003年   6417篇
  2002年   6401篇
  2001年   6432篇
  2000年   6029篇
  1999年   6051篇
  1998年   13788篇
  1997年   10149篇
  1996年   7655篇
  1995年   5736篇
  1994年   5236篇
  1993年   5144篇
  1992年   4009篇
  1991年   3808篇
  1990年   3870篇
  1989年   3824篇
  1988年   3579篇
  1987年   3061篇
  1986年   3094篇
  1985年   3466篇
  1984年   3357篇
  1983年   3099篇
  1982年   2737篇
  1981年   2955篇
  1980年   2689篇
  1979年   2857篇
  1978年   2755篇
  1977年   2921篇
  1976年   3823篇
  1975年   2466篇
  1974年   2301篇
  1973年   2329篇
  1972年   1990篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
62.
The effect of the composition of sensitizing–activating solutions on the activation efficiency and the chemical coppering of diamond powders is studied. The results demonstrate that stabilizing additives improve the stability of the solutions, influence the average coppering rate, and play a key role in determining the morphology and quality of the resultant coatings. The most effective stabilizing additive is synthamid-10, which ensures the deposition of high-quality copper coatings.  相似文献   
63.
The TELEMAC project brings new methodologies from the Information and Science Technologies field to the world of water treatment. TELEMAC offers an advanced remote management system which adapts to most of the anaerobic wastewater treatment plants that do not benefit from a local expert in wastewater treatment. The TELEMAC system takes advantage of new sensors to better monitor the process dynamics and to run automatic controllers that stabilise the treatment plant, meet the depollution requirements and provide a biogas quality suitable for cogeneration. If the automatic system detects a failure which cannot be solved automatically or locally by a technician, then an expert from the TELEMAC Control Centre is contacted via the internet and manages the problem.  相似文献   
64.
Polystyrene packaging material taint was sensorily evaluated in cocoa powder for drinks and chocolate flakes using short-cut signal detection measures on differences between control and test samples and on recognition of styrene. No differences were observed in cocoa powder for drinks and plain chocolate flakes treated with 0.5 dm2 polystyrene of 1 mm thickness. However, differences were detected in milk chocolate flakes and plain chocolate flakes, which were in contact with a larger area or thicker polystyrene packaging material. The latter results were confirmed by the styrene recognition test, so polystyrene is a potential source of off-flavour for chocolate products. The amount of residual styrene in the polystyrene used was about 320 ppm, while the amounts of styrene ranged from 7 to 132 ppb in cocoa drinks and from 414 to 1447 ppb in chocolate flakes.  相似文献   
65.
66.
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   
67.
We present local least squares and regularization frameworks for computing 3D velocity (3D optical flow) from 3D radial velocity measured by a Doppler radar. We demonstrate the performance of our algorithms quantitatively on synthetic radial velocity data and qualitatively on real radial velocity data, obtained from the Doppler radar at Kurnell Radar station, Botany Bay, New South Wales, Australia. Radial velocity can be used to predict the future positions of storms in sequences of Doppler radar datasets.© 2005 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 15, 189–198, 2005  相似文献   
68.
The ennoblement of corrosion potential (Ecorr) of passive metal immersed in seawater was investigated with electrochemical technology and epifluorescence microscopy. The in situ observation showed that the bacteria number increased on the metal surface according to an exponential law which was in the same way with the ennoblement of Ecorr. At the same time, the anodic polarization current of high‐Mo stainless steel decreased in the initial days. According to the mix‐potential theory and the characteristics of polarization curves of high‐Mo steel in natural seawater, the ennoblement of corrosion potential may be induced by the decrease of the passive current density.  相似文献   
69.
Since the topological entropy of a vast class of two-dimensional cellular automata (CA) is infinite, of interest is the possibility to renormalize it so that to obtain a positive finite value. We find the asymptotics of the information function of a multidimensional CA and, accordingly, introduce the renormalized topological entropy as a coefficient of this asymptotics. We describe some properties of the introduced quantity, in particular, its positivity for CA of the type of “The Game of Life.” Also, we give an example of an explicit evaluation of this parameter for a particular cellular automaton.  相似文献   
70.
Power distribution systems have been significantly affected by many outage-causing events. Good fault cause identification can help expedite the restoration procedure and improve the system reliability. However, the data imbalance issue in many real-world data sets often degrades the fault cause identification performance. In this paper, the E-algorithm, which is extended from the fuzzy classification algorithm by Ishibuchi to alleviate the effect of imbalanced data constitution, is applied to Duke Energy outage data for distribution fault cause identification. Three major outage causes (tree, animal, and lightning) are used as prototypes. The performance of E-algorithm on real-world imbalanced data is compared with artificial neural network. The results show that the E-algorithm can greatly improve the performance when the data are imbalanced  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