全文获取类型
收费全文 | 664篇 |
免费 | 33篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 119篇 |
金属工艺 | 19篇 |
机械仪表 | 14篇 |
建筑科学 | 16篇 |
能源动力 | 33篇 |
轻工业 | 47篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 125篇 |
一般工业技术 | 144篇 |
冶金工业 | 81篇 |
自动化技术 | 92篇 |
出版年
2023年 | 6篇 |
2022年 | 11篇 |
2021年 | 18篇 |
2020年 | 4篇 |
2019年 | 12篇 |
2018年 | 18篇 |
2017年 | 30篇 |
2016年 | 25篇 |
2015年 | 10篇 |
2014年 | 24篇 |
2013年 | 37篇 |
2012年 | 33篇 |
2011年 | 49篇 |
2010年 | 26篇 |
2009年 | 41篇 |
2008年 | 24篇 |
2007年 | 22篇 |
2006年 | 24篇 |
2005年 | 28篇 |
2004年 | 16篇 |
2003年 | 13篇 |
2002年 | 13篇 |
2001年 | 13篇 |
2000年 | 16篇 |
1999年 | 19篇 |
1998年 | 30篇 |
1997年 | 12篇 |
1996年 | 13篇 |
1995年 | 13篇 |
1994年 | 13篇 |
1993年 | 13篇 |
1992年 | 3篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1987年 | 3篇 |
1986年 | 7篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 9篇 |
1974年 | 2篇 |
1971年 | 2篇 |
1959年 | 1篇 |
排序方式: 共有701条查询结果,搜索用时 406 毫秒
1.
Human faces undergo considerable amounts of varialions with aging. While face recognition systems have been proven to be sensitive to factors such as illumination and pose, their sensitivity to facial aging effects is yet to be studied. How does age progression affect the similarity between a pair of face images of an individual? What is the confidence associated with establishing the identity between a pair of age separated face images? In this paper, we develop a Bayesian age difference classifier that classifies face images of individuals based on age differences and performs face verification across age progression. Further, we study the similarity of faces across age progression. Since age separated face images invariably differ in illumination and pose, we propose preprocessing methods for minimizing such variations. Experimental results using a database comprising of pairs of face images that were retrieved from the passports of 465 individuals are presented. The verification system for faces separated by as many as nine years, attains an equal error rate of 8.5%. 相似文献
2.
3.
M Manickam M Ramanathan MA Jahromi JP Chansouria AB Ray 《Canadian Metallurgical Quarterly》1997,60(6):609-610
Glucose levels in rats with hyperglycemia induced by streptozotocin were determined after i.p. administration of marsupsin (1), pterosupin (2), and pterostilbene (3), three important phenolic constituents of the heartwood of Pterocarpus marsupium. Marsupsin and pterostilbene significantly lowered the blood glucose level of hyperglycemic rats, and the effect was comparable to that of 1,1-dimethylbiguanide (metformin). 相似文献
4.
Control of volatile organic compounds by an AC energizedferroelectric pellet reactor and a pulsed corona reactor 总被引:1,自引:0,他引:1
Yamamoto T. Ramanathan K. Lawless P.A. Ensor D.S. Newsome J.R. Plaks N. Ramsey G.H. 《Industry Applications, IEEE Transactions on》1992,28(3):528-534
Two laboratory-scale plasma reactors, an alternating current (AC) energized ferroelectric (high dielectric ceramic) packed bed reactor and a nanosecond pulsed corona reactor, were constructed. This study was done to develop baseline engineering data to demonstrate the feasibility of the application of plasma reactors to the destruction of various volatile organic compounds (VOCs) at PPM levels. Complete destruction was obtained for toluene. Conversions of methylene chloride at 95% and trichlorotrifluoroethane (known as CFC-113) at 67% were achieved for the plasma reactors used. The conversion was dependent on the mean electron energy in the reactor and was also related to how strongly halogen species were bonded with carbon 相似文献
5.
6.
Hyun-Ho Choi Sang-Yoon Lee Il-Yoon Choi Hyo-Nam Cho Sankaran Mahadevan 《Reliability Engineering & System Safety》2006,91(6):674-688
Until now, in many forensic reports, the failure cause assessments are usually carried out by a deterministic approach so far. However, it may be possible for the forensic investigation to lead to unreasonable results far from the real collapse scenario, because the deterministic approach does not systematically take into account any information on the uncertainties involved in the failures of structures.Reliability-based failure cause assessment (reliability-based forensic engineering) methodology is developed which can incorporate the uncertainties involved in structural failures and structures, and to apply them to the collapsed bridge in order to identify the most critical failure scenario and find the cause that triggered the bridge collapse. Moreover, to save the time and cost of evaluation, an algorithm of automated event tree analysis (ETA) is proposed and possible to automatically calculate the failure probabilities of the failure events and the occurrence probabilities of failure scenarios. Also, for reliability analysis, uncertainties are estimated more reasonably by using the Bayesian approach based on the experimental laboratory testing data in the forensic report. For the applicability, the proposed approach is applied to the Hang-ju Grand Bridge, which collapsed during construction, and compared with deterministic approach. 相似文献
7.
8.
9.
10.
We formulate the problem of multicast tree generation as one of computing a directed Steiner tree of minimal cost. In this context, we present a polynomial-time algorithm that provides for trade-off selection, using a single parameter κ, between the tree-cost (Steiner cost) and the run time efficiency. Further, the same algorithm may be used for delay optimization or tree-cost minimization simply by configuring the value of κ appropriately. We present theoretical and experimental analysis characterizing the problem and the performance of our algorithm. Theoretically, we show that it is highly unlikely that there exists a polynomial-time algorithm with a performance guarantee of constant times optimum cost, introduce metrics for measuring the asymmetry of graphs, and show that the worst-case cost of the tree produced by our algorithm is, at most, twice the optimum cost times the asymmetry, for two of these asymmetry metrics. For graphs with bounded asymmetry, this gives constant times optimum performance guarantee. We also show that three well-known algorithms for (undirected) Steiner trees are but particular cases of our algorithm. Our experimental study shows that operating at a low κ gives nearly best possible expected tree cost while maintaining acceptable run-time efficiency 相似文献