全文获取类型
收费全文 | 817篇 |
免费 | 63篇 |
国内免费 | 16篇 |
专业分类
电工技术 | 64篇 |
综合类 | 14篇 |
化学工业 | 136篇 |
金属工艺 | 31篇 |
机械仪表 | 47篇 |
建筑科学 | 15篇 |
矿业工程 | 5篇 |
能源动力 | 25篇 |
轻工业 | 30篇 |
水利工程 | 12篇 |
石油天然气 | 13篇 |
武器工业 | 7篇 |
无线电 | 71篇 |
一般工业技术 | 156篇 |
冶金工业 | 106篇 |
原子能技术 | 4篇 |
自动化技术 | 160篇 |
出版年
2023年 | 12篇 |
2022年 | 28篇 |
2021年 | 22篇 |
2020年 | 31篇 |
2019年 | 19篇 |
2018年 | 29篇 |
2017年 | 23篇 |
2016年 | 21篇 |
2015年 | 18篇 |
2014年 | 33篇 |
2013年 | 60篇 |
2012年 | 53篇 |
2011年 | 39篇 |
2010年 | 31篇 |
2009年 | 35篇 |
2008年 | 28篇 |
2007年 | 36篇 |
2006年 | 18篇 |
2005年 | 23篇 |
2004年 | 19篇 |
2003年 | 13篇 |
2002年 | 22篇 |
2001年 | 18篇 |
2000年 | 18篇 |
1999年 | 13篇 |
1998年 | 33篇 |
1997年 | 24篇 |
1996年 | 23篇 |
1995年 | 19篇 |
1994年 | 13篇 |
1993年 | 10篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 12篇 |
1988年 | 3篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 13篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 11篇 |
1976年 | 6篇 |
1974年 | 4篇 |
1973年 | 2篇 |
排序方式: 共有896条查询结果,搜索用时 15 毫秒
821.
Chia‐Hsuan Pai Ting‐Yi Cho Shih‐Chi Tsai Chung‐Yi Chiu Te‐Sheng Chen Hsi‐Chien Lin Jenn‐Jia Su Alan Lien 《Journal of the Society for Information Display》2010,18(11):960-967
Abstract— Polymer stabilization is introduced in VA‐type LCDs, and fast response time can be achieved along with a high contrast ratio.1 A small amount of reactive monomer is mixed with liquid crystal and forms a polymer layer above the alignment layer by using a UV process. The pre‐tilt angle of the liquid crystal is stabilized, and a faster response time can be realized when the bias pre‐tilt angle from 90° is increased. The properties of reactive monomers and liquid crystal and the conditions of the UV process were studied. Based on the application of the proper monomer and LC, and an optima UV process, a 65‐in. 240‐Hz full‐HD TFT‐LCD, with a faster response time and high contrast ratio, has been developed. 相似文献
822.
We present an approach for exact maximum likelihood estimation of parameters from univariate and multivariate autoregressive fractionally integrated moving average models with Gaussian errors using the Expectation Maximization (EM) algorithm. The method takes advantage of the relation between the VARFIMA(0,d,0) process and the corresponding VARFIMA(p,d,q) process in the computation of the likelihood. 相似文献
823.
824.
Xuan Li Chun‐Ho Chen Yi‐Pai Huang 《Journal of the Society for Information Display》2016,24(8):521-528
A bare‐finger 3D interactive technology for portable devices was developed. Using directive‐flective cameras to reform the field of viewing, a blind working range close to the camera is eliminated. Moreover, the algorithm of vision computing, different from skin color detection, is presented to determine the positions of fingertips. The interactive range is workable from 1.5 to 50 cm above the entire surface of the display. The mean position error of less than 1 cm is achieved. This accuracy realizes a camera‐based 3D interactive system allowing for near‐distance functionality. Therefore, floating 3D images can be touched and interacted with, potentially creating more application and intuitive user‐machine interface. 相似文献
825.
The influence of MnO2, CuO, and NiO on the thermal decomposition and explosivity of arylammonium perchlorates has been studied by differential thermal analysis (DTA) and explosive sensitivity measurements. The metal oxides considerably sensitize both decomposition and explosion and the sensitizing effect is in the order NiO < CuO < MnO2. The accelerated decomposition or explosion seems to occur via the formation of an intermediate, metal perchlorate arylamine complex. The experimental evidence for the mechanism put forward has been included. 相似文献
826.
S. McGovern G. Harish C.S. Pai W. Mansfield J.A. Taylor S. Pau R.S. Besser 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(3):382-390
BACKGROUND: Multiphase hydrogenation plays a critical role in the pharmaceutical industry. A significant portion of the reaction steps in a typical fine chemical synthesis are catalytic hydrogenations, generally limited by resistances to mass and heat transport. To this end, the small‐scale and large surface‐to‐volume ratios of microreactor technology would greatly benefit chemical processing in the pharmaceutical and other industries. A silicon microreactor has been developed to investigate mass transfer in a catalytic hydrogenation reaction. The reactor design is such that solid catalyst is suspended in the reaction channel by an arrangement of catalyst traps. The design supports the use of commercial catalyst and allows control of pressure drop across the bed by engineering the packing density. RESULTS: This paper discusses the design and operation of the reactor in the context of the liquid‐phase hydrogenation of o‐nitroanisole to o‐anisidine. A two‐phase ‘flow map’ is generated across a range of conditions depicting three flow regimes, termed gas‐dominated, liquid‐dominated, and transitional, all with distinctly different mass transfer behavior. Conversion is measured across the flow map and then reconciled against the mass transfer characteristics of the prevailing flow regime. The highest conversion is achieved in the transitional flow regime, where competition between phases induces the most favorable gas–liquid mass transfer. CONCLUSION: The results are used to associate a mass transfer coefficient with each flow regime to quantify differences in performance. This reactor architecture may be useful for catalyst evaluation through rapid screening, or in large numbers as an alternative to macro‐scale production reactors. Copyright © 2008 Society of Chemical Industry 相似文献
827.
Kwentus A.Y. Pai P. Jaffe S. Gomez R. Tsai S. Kwan T. Hing-Tsun Hung Shin Y.J. Hue V. Cheung D. Khan R.A. Ward C.M. Mong-Kai Ku Choi K. Searle J. Bult K. Cameron K. Demas J. Reames C. Samueli H. 《Solid-State Circuits, IEEE Journal of》1999,34(11):1634-1646
This paper presents a complete single-chip universal digital satellite receiver supporting all current DBS system standards. The mixed-signal device accepts a modulated data stream at up to 90 Mbps and delivers a demodulated, error-corrected output data stream. The IC features an analog front end with 480-MHz intermediate frequency downconversion and dual 8-bit analog-to-digital converters, an all-digital BPSK/QPSK/OQPSK variable-rate receiver supporting 1-45 MBaud operation with phase/frequency recovery, variable-rate digital filters, square-root Nyquist matched filters, acquisition and tracking loops, and a DVB/DSS/DigiCipher I/II-compliant concatenated Viterbi/Reed-Solomon forward error correction decoder with on-chip deinterleaver RAM. All required clocks are generated on chip from a single reference crystal. The chip contains 1.2 million transistors in a die area of 22 mm2 and was implemented in a single-poly 0.35-μm CMOS process with four layers of metal 相似文献
828.
Potential assessment of the support vector regression technique in rainfall forecasting 总被引:2,自引:2,他引:0
Forecasting and monitoring of rainfall values are increasingly important for decreasing economic loss caused by flash floods.
Based on statistical learning theory, support vector regression (SVR) has been used to deal with forecasting problems. Performing
structural risk minimization rather than minimizing the training errors, SVR algorithms have better generalization ability
than the conventional artificial neural networks. The objective of this investigation is to examine the feasibility and applicability
of SVR in forecasting volumes of rainfall during typhoon seasons. In addition, Simulated Annealing (SA) algorithms are employed
to choose parameters of the SVR model. Subsequently, rainfall values during typhoon periods in Taiwan's Wu–Tu watershed are
used to demonstrate the forecasting performance of the proposed model. The simulation results show that the proposed SVRSA
model is a promising alternative in forecasting amounts of rainfall during typhoon seasons. 相似文献
829.
对R41和混合工质CO2/R41 (20.5/79.5)、CO2/R41(51.4/48.6)在直径为2 mm的水平光滑圆管中的超临界冷却流动换热特性进行了实验研究。质量流速范围为400~800 kg·m-2·s-1,压力为6.0~8.0 MPa,热通量为12~48 kW·m-2,流体温度为20~80℃。3种工质的对流传热系数的极值随CO2含量的增加而增大,在相同条件下R41的传热系数小于CO2/R41的传热系数。混合物的超临界传热系数变化规律与纯R41相同。实验条件下,3种流体的传热系数在2~25 kW·m-2·K-1之间,压力的影响显著,越接近临界压力对应压力条件下的传热系数极值越高。在远离准临界点的区域传热系数随热通量变化不明显,而在准临界点附近对流传热系数的极值随热通量的增加而小幅减小。将实验结果与经验关联式计算结果进行了比较,有4个关联式的预测效果较好,误差均在±30%以内,预测误差随CO2含量的增加而下降。 相似文献
830.
K. K. Ajith Kumar Abhilash Viswanath T. P. D. Rajan U. T. S. Pillai B. C. Pai 《金属学报(英文版)》2014,27(2):295-305
In the present investigation, composites with silicon carbide particle (SiCp) as reinforcement and AZ91 magnesium alloy as matrix have been synthesized using liquid metal stir-casting technique with optimized processing conditions. The composites with good particle distribution in the matrix, and better grain refinement and good interfacial bonding between the matrix and reinforcement have been obtained. The effect of SiCp content on the physical, mechanical, and tribological properties of Mg-based metal matrix composite (MMC) is studied with respect to particle distribution, grain refinement, and particle/matrix interfacial reactions. The electrical conductivity, coefficient of thermal expansion, microas well as macro-hardness, tensile and compressive properties, and the fracture behavior of the composites along with dry sliding wear of the composites have been evaluated and compared with the base alloy. 相似文献