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   169篇
  免费   2篇
电工技术   33篇
化学工业   29篇
金属工艺   4篇
机械仪表   2篇
建筑科学   1篇
能源动力   7篇
轻工业   19篇
水利工程   2篇
无线电   6篇
一般工业技术   20篇
冶金工业   34篇
原子能技术   5篇
自动化技术   9篇
  2023年   2篇
  2022年   1篇
  2021年   1篇
  2020年   2篇
  2019年   2篇
  2018年   2篇
  2017年   4篇
  2016年   3篇
  2014年   6篇
  2013年   11篇
  2012年   6篇
  2011年   6篇
  2010年   6篇
  2009年   4篇
  2008年   3篇
  2007年   4篇
  2006年   3篇
  2005年   10篇
  2004年   11篇
  2003年   6篇
  2002年   3篇
  2001年   4篇
  2000年   1篇
  1999年   3篇
  1998年   7篇
  1997年   6篇
  1996年   5篇
  1995年   4篇
  1994年   3篇
  1993年   2篇
  1992年   4篇
  1991年   4篇
  1990年   2篇
  1989年   2篇
  1987年   4篇
  1986年   1篇
  1985年   4篇
  1984年   4篇
  1983年   2篇
  1982年   1篇
  1981年   2篇
  1980年   2篇
  1978年   1篇
  1977年   2篇
  1976年   4篇
  1957年   1篇
排序方式: 共有171条查询结果,搜索用时 15 毫秒
91.
The stereoisomeric composition of the copulation release pheromone of the azuki bean weevil, Callosobruchus chinensis L., was determined to be R:S = 3.3–3.4:1 by the 2D-Ohrui–Akasaka method.  相似文献   
92.
This paper describes an optimal load-shedding method which can be applied to local buses in order to suppress voltage deviations, based on local information obtained at each bus. When a generation outage occurs, adequate amounts of loads must be shed within a few seconds in order to maintain the balance between supply and demand. This method is able to decide quickly the optimal amounts of loads to be shed after the fault. The proposed method is based on the fact that the location of the fault can be estimated exclusively from power flow deviations at local buses, measured after the outage. Because the amounts of load to be shed have constraints, it is necessary to find the optimal factors which decide the amounts of load-shedding at each bus by quadratic programming. To solve this problem we first linearize the study system. Next, in order to relate power flows to voltage deviations at each bus, the voltage sensitivity factors obtained by ac power flow calculation are evaluated. Numerical simulations with 4-machine and 9-machine power system models show the effectiveness of the proposed method. It distributes adequate loads which are almost identical to the completely optimized loads, and it produces smaller voltage deviations than the conventional method. Improved transient characteristics of voltage deviations are also demonstrated. © 1997 Scripta Technica, Inc. Electr Eng Jpn 119(1): 35–44, 1997  相似文献   
93.
Wind power generation using an unlimited, natural energy has been getting attention regarding environmental issues in recent years, and the installed capacity of wind power generation system is increasing at a rapid pace, resulting in deterioration of power quality especially in frequency and voltage. This fact will be a big problem in restricting large capacity of wind farms. This paper proposes a new frequency converter: rotary frequency converter (RFC) to moderate the electric output from wind generation, which is to be installed between a set of wind generators and a grid, providing a smoothed electric output, promoting the wind power generation introduction. This mainly consists of a synchronous machine and the adjustable‐speed machine. Independent controls of input/output voltage, active power, and reactive power offer electrical separation between the two networks. Experimental study of a prototype model and its characteristics, especially dynamic control, is discussed in this paper. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(4): 26–34, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20922  相似文献   
94.
In this study, the effectiveness of aerobic granular sludge as seed sludge for rapid start-up of nitrifying processes was investigated using a laboratory-scale continuous stirred-tank reactor (CSTR) fed with completely inorganic wastewater which contained a high concentration of ammonia. Even when a large amount of granular biomass was inoculated in the reactor, and the characteristics of influent wastewater were abruptly changed, excess biomass washout was not observed, and biomass concentration was kept high at the start-up period due to high settling ability of the aerobic granular sludge. As a result, an ammonia removal rate immediately increased and reached more than 1.0 kg N/m(3)/d within 20 days and up to 1.8 kg N/m(3)/d on day 39. Subsequently, high rate nitritation was stably attained during 100 days. However, nitrite accumulation had been observed for 140 days before attaining complete nitrification to nitrate. Fluorescence in situ hybridization analysis revealed the increase in amount of ammonia-oxidizing bacteria which existed in the outer edge of the granular sludge during the start-up period. This microbial ecological change would make it possible to attain high rate ammonia removal.  相似文献   
95.
介绍了以 MESFET构成的微波放大器的 2种稳定化方法 ;在栅漏间或栅源间插入 RCL串联支路。分析了在这两种方法中 ,稳定化因子 K以及电路增益与 RCL参数的关系。  相似文献   
96.
Occurrence of n−5 monounsaturated fatty acids in jujube pulp lipids   总被引:1,自引:0,他引:1  
The pulp lipids of jujube (Zizyphus jujuba var.inermis) fruit have been shown by chromatographic, spectrometric and chemical analyses to contain a series ofcis-monoenoic fatty acids with n−5 unsaturation as major acyl moieties. The total concentration of these n−5 fatty acids, such as 14∶1n−5, 16∶1n−5 and 18∶1n−5, ranged from 22 to 54% of total fatty acids in the pulp lipids of 11 different sources. The main component of the n−5 homologues was 16∶1n−5 in all cases. Other monoenoic acids with n−7 unsaturation, namely palmitoleic (cis-9-hexadecenoic) acid andcis-vaccenic (cis-11-octadecenoic) acid, as well as with n−9 unsaturation, namely oleic acid, were also identified. In the seed lipids of jujube fruit, none of the n−5 monoenoic acids could be detected. Thus the jujube pulp lipids are characterized by the predominance of n−5 monoenoic acid isomers.  相似文献   
97.
98.
Src, the prototype of Src family kinases (SFKs), is a modular protein consisting of SH4 (SH4) and unique (UD) domains in an N-terminal intrinsically disordered region (IDR), and SH3, SH2, and kinase (KD) folded domains conserved among SFKs. Src functions as a pleiotropic signaling hub in proliferating and post-mitotic cells, and it is related to cancer and neurological diseases. However, its regulatory mechanism is unclear because the existing canonical model is derived from crystallographic analyses of folded constructs lacking the IDR. This work reviews nuclear magnetic resonance analyses of partially structured lipid-binding segments in the flexible UD and the fuzzy intramolecular complex (FIMC) comprising IDR and SH3 domains, which interacts with lipid membranes and proteins. Furthermore, recently determined IDR-related Src characteristics are discussed, including dimerization, SH4/KD intramolecular fastener bundling of folded domains, and the sorting of adhesive structures. Finally, the modulatory roles of IDR phosphorylation in Src activities involving the FIMC are explored. The new regulatory roles of IDRs are integrated with the canonical model to elucidate the functions of full-length Src. This review presents new aspects of Src regulation, and provides a future direction for studies on the structure and function of Src, and their implications for pathological processes.  相似文献   
99.
INTRODUCTIONCatalytic combushon is considered to be an effechvecombushon method for gas tUrbines to achieve lower NOxendssion levels. However, a Problem to be solved is theexcess increase of catalyst temp~ that easily causesdamage. Lindhng catalyst temperathe can be realized byallowing incomplete combushon in catalyst by combininga flame holder downstream that yields completecombushon afterWards. iiis is recognized as the mostadvantageous combushon method that meets the thermalresistance…  相似文献   
100.
An efficient method for conversion of allitol to D-psicose was achieved by a resting cell reaction of Bacillus pallidus Y25 for the first time. Notably, it was possible to produce D-allose and D-altrose from allitol directly via D-psicose by prolonging the reaction time. This method was applied for the preparation of D-psicose using the extract of Itea virginica as a starting material in this study. D-Psicose which is the absolutely key precursor for the production of other six carbon sugars could be obtained as the sole product at high yield.  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