全文获取类型
收费全文 | 34374篇 |
免费 | 3518篇 |
国内免费 | 2081篇 |
专业分类
电工技术 | 2433篇 |
技术理论 | 1篇 |
综合类 | 2558篇 |
化学工业 | 5237篇 |
金属工艺 | 1837篇 |
机械仪表 | 2201篇 |
建筑科学 | 2859篇 |
矿业工程 | 1040篇 |
能源动力 | 1118篇 |
轻工业 | 2282篇 |
水利工程 | 794篇 |
石油天然气 | 1594篇 |
武器工业 | 251篇 |
无线电 | 4177篇 |
一般工业技术 | 3816篇 |
冶金工业 | 1432篇 |
原子能技术 | 689篇 |
自动化技术 | 5654篇 |
出版年
2024年 | 191篇 |
2023年 | 580篇 |
2022年 | 1007篇 |
2021年 | 1456篇 |
2020年 | 1109篇 |
2019年 | 992篇 |
2018年 | 979篇 |
2017年 | 1139篇 |
2016年 | 1066篇 |
2015年 | 1376篇 |
2014年 | 1810篇 |
2013年 | 1989篇 |
2012年 | 2161篇 |
2011年 | 2482篇 |
2010年 | 2266篇 |
2009年 | 2154篇 |
2008年 | 2019篇 |
2007年 | 1971篇 |
2006年 | 2029篇 |
2005年 | 1585篇 |
2004年 | 1253篇 |
2003年 | 1181篇 |
2002年 | 1356篇 |
2001年 | 1105篇 |
2000年 | 916篇 |
1999年 | 831篇 |
1998年 | 558篇 |
1997年 | 451篇 |
1996年 | 411篇 |
1995年 | 303篇 |
1994年 | 268篇 |
1993年 | 193篇 |
1992年 | 162篇 |
1991年 | 146篇 |
1990年 | 104篇 |
1989年 | 87篇 |
1988年 | 76篇 |
1987年 | 33篇 |
1986年 | 47篇 |
1985年 | 19篇 |
1984年 | 18篇 |
1983年 | 14篇 |
1982年 | 14篇 |
1981年 | 7篇 |
1980年 | 11篇 |
1979年 | 10篇 |
1978年 | 9篇 |
1976年 | 5篇 |
1959年 | 7篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Designing circuits with partial scan 总被引:1,自引:0,他引:1
Agrawal V.D. Kwang-Ting Cheng Johnson D.D. Sheng Lin T. 《Design & Test of Computers, IEEE》1988,5(2):8-15
In this scan design methodology, only selected faults are targeted for detection. These faults are those not detected by the designer's functional vectors. The test generator decides exactly which flip-flops should be scanned using one of two methods. In the first method, all possible tests are generated for each target fault, and the set of tests requiring the fewest flip-flops is selected. In the second method, only one test is generated for each fault, and the use of flip-flops is avoided as much as possible during test generation. Examples of actual VLSI circuits show a savings of at least a 40% in full-scan overhead 相似文献
92.
Ao Sheng Rong Zhong Liang Sun 《Antennas and Propagation, IEEE Transactions on》1991,39(9):1366-1371
The radiation of millimeter waves from the nonradiative dielectric (NRD) leaky wave antennas with the tapered transition and the tuning aperture is investigated. An accurate theory for the leakage constant and the phase constant of the antennas is presented, which is based on the generalized scattering parameters considering the higher-order mode interactions at the discontinuities. The associated transverse equivalent network involves the characterization of the mode couplings at two air-to-dielectric interfaces, the coupled mode analysis of the tapered transition, and the calculation of the radiation fields at the tuning aperture via the extended spectral domain approach. The interesting behavior of the present modified configuration of NRD leaky wave antennas is illustrated by typical examples. The validity of the theory is confirmed by the comparison of the theoretical results with experimental data for the limiting cases 相似文献
93.
94.
Process optimisation and optimal control of batch and continuous drum granulation processes are studied in this paper. The main focus of the current research has been: (i) construction of optimisation and control relevant, population balance models through the incorporation of moisture content, drum rotation rate and bed depth into the coalescence kernels; (ii) investigation of optimal operational conditions using constrained optimisation techniques; (iii) development of optimal control algorithms based on discretized population balance equations; and (iv) comprehensive simulation studies on optimal control of both batch and continuous granulation processes. The objective of steady state optimisation is to minimise the recycle rate with minimum cost for continuous processes. It has been identified that the drum rotation-rate, bed depth (material charge), and moisture content of solids are practical decision (design) parameters for system optimisation. The objective for the optimal control of batch granulation processes is to maximize the mass of product-sized particles with minimum time and binder consumption. The objective for the optimal control of the continuous process is to drive the process from one steady state to another in a minimum time with minimum binder consumption, which is also known as the state-driving problem. It has been known for some time that the binder spray-rate is the most effective control (manipulative) variable. Although other possible manipulative variables, such as feed flow-rate and additional powder flow-rate have been investigated in the complete research project, only the single input problem with the binder spray rate as the manipulative variable is addressed in the paper to demonstrate the methodology. It can be shown from simulation results that the proposed models are suitable for control and optimisation studies, and the optimisation algorithms connected with either steady state or dynamic models are successful for the determination of optimal operational conditions and dynamic trajectories with good convergence properties. 相似文献
95.
96.
MX345芯片用于产生模拟信令—CTCSS单音.本文在介绍MX345编码/解码器工作原理的基础上,设计出MX345芯片与单片机的接口电路.最后给出控制软件. 相似文献
97.
稠油热采注汽管道由于长期在高温、高压下运行,极易发生各种损伤,如腐蚀、裂纹、材料退化等,极易造成管道承压能力降低,发生失效事故。如何检测出潜在危险性缺陷,判断注汽管道能否继续使用,是保证注汽管道安全运行的关键问题。探讨了高温压力管道在线检测技术发展现状及其应用范围。 相似文献
98.
葛翔 《石油化工安全环保技术》2006,22(4):37-38,43
阐述了现场总线技术的含义、主要特点和优点,对比了现场总线控制系统与DCS系统的区别,介绍了现场总线技术在洛阳石化分公司热电站的典型应用及其发展前景。 相似文献
99.
Guiying Li Ze He Taicheng An Xiangying Zeng Guoying Sheng Jiamo Fu 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(7):1019-1026
BACKGROUND: To investigate the microbial degradation performance of organic pollutants in the atmosphere using a biotrickling filter, two microorganism strains, Bacillus cereus S1 and Bacillus cereus S2, were selected, identified and inoculated into a twin biotrickling filter for comparison. RESULTS: Both strains showed good performance towards the degradation of model organic pollutants when gas flow rates ranged from 100 to 600 L h−1. For S1, the total maximum removal efficiency (RE) of toluene was maintained nearly 100% not only at gas flow rates of 100 L h−1 corresponding to empty bed residence time (EBRT) 199.44 s, but also at gas flow rates of 200 L h−1 (EBRT = 99.72 s) and 300 L h−1 (EBRT = 66.48 s). However, S2 had a much lower degradation capability; near 100% removal efficiency was obtained only at the gas flow rate of 100 L h−1 although both bacteria belong to the same Bacillus cereus. With further increase in gas flow rate, the total REs for both S1 and S2 decreased slightly at first and then dropped sharply to 46% and 35%, respectively, at an EBRT of 33.24 s, corresponding to a gas flow rate of 600 L h−1. Starvation for between 2 and 10 days resulted in the re‐acclimation times of both strains ranging between 1.0 and 15.5 h. CONCLUSION: Strain S1 would be a better choice for inoculation into a biotrickling filter than strain S2, because of its much higher toluene removal capacity and rapid recovery to full performance. Copyright © 2008 Society of Chemical Industry 相似文献
100.
Poly(3-n-octyloxythiophene), a conjugated polymer, which possessed solubility in common organic solvents, was synthesized by electrochemical polymerization in the presence of lithium perchlorate as the supporting electrolyte and sodium dodecyl sulfate as the surfactant in an aqueous medium. Characterizations of the intermediate, monomer, and polymer were performed by NMR spectroscopy, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, and gel permeation chromatography. The process of electrochemical polymerization and the electrochemical redox behaviors were investigated by cyclic voltammetry and the potentiostatic method. A poly(3-n-octyloxythiophene) film that was deposited on a platinum electrode was found to exhibit electrochromic behaviors, and it switched electrochemically between blue–green oxidized and dark red reduced states. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献