全文获取类型
收费全文 | 615篇 |
免费 | 12篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 88篇 |
金属工艺 | 9篇 |
机械仪表 | 9篇 |
建筑科学 | 35篇 |
能源动力 | 5篇 |
轻工业 | 56篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 58篇 |
一般工业技术 | 83篇 |
冶金工业 | 181篇 |
原子能技术 | 13篇 |
自动化技术 | 81篇 |
出版年
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2018年 | 8篇 |
2017年 | 8篇 |
2016年 | 5篇 |
2015年 | 5篇 |
2014年 | 7篇 |
2013年 | 30篇 |
2012年 | 8篇 |
2011年 | 18篇 |
2010年 | 9篇 |
2009年 | 13篇 |
2008年 | 17篇 |
2007年 | 18篇 |
2006年 | 34篇 |
2005年 | 16篇 |
2004年 | 17篇 |
2003年 | 10篇 |
2002年 | 16篇 |
2001年 | 9篇 |
2000年 | 11篇 |
1999年 | 10篇 |
1998年 | 51篇 |
1997年 | 34篇 |
1996年 | 25篇 |
1995年 | 18篇 |
1994年 | 13篇 |
1993年 | 20篇 |
1992年 | 13篇 |
1991年 | 10篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 12篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 3篇 |
1982年 | 8篇 |
1981年 | 5篇 |
1980年 | 10篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 8篇 |
1976年 | 14篇 |
1975年 | 9篇 |
1974年 | 4篇 |
1973年 | 5篇 |
1971年 | 3篇 |
排序方式: 共有627条查询结果,搜索用时 0 毫秒
1.
Containment structures have several regions in which the continuity of the cylindrical pressure boundary is interrupted, e.g., shell penetrations, discontinuous stiffeners, and changes in the shell thickness. Significant strain concentrations can occur in these areas of discontinuity. The Sandia National Laboratories 1:8-scale steel containment equipment hatch was analyzed as an example of an eccentricity at a stiffener intersection.A portion of the as-built 1:8-scale model was modeled with the ANSYS general purpose finite element program using triangular, thin shell finite elements. The overall size of the model was determined from Saint-Venant type considerations of the stress field around the hatch. Shell elements were used to model the ring and formed stiffeners. Geometric and material nonlinear behavior were included. The model was loaded using discrete load steps up to a pressure of 165 psig. At this pressure, the maximum strain was 19.7 percent in the formed stiffener near its intersection with the ring stiffener. The finite element solution demonstrated the very localized nature of the strain field near the ring/formed stiffener intersection.In an attempt to reduce analysis costs, a small portion of the 1:8-scale model immediately surrounding the ring/formed stiffener intersection was selected for further analysis. Two smaller models, a ring/formed stiffener intersection and a ring/circular stiffener intersection, were studied. The models were significantly smaller than the regions used previously. A comparison of the two intersection models showed that the circular stiffener is a more efficient configuration. 相似文献
2.
3.
Blair J.D. Correale A. Jr. Cranford H.C. Dombrowski D.A. Erdelyi C.K. Hoffman C.R. Lamphere J.L. Lang K.W. Lee J.K. Mullen J.M. Norman V.R. Oakland S.F. 《Solid-State Circuits, IEEE Journal of》1989,24(6):1647-1655
The authors describe a 9.02×9.02-mm chip built in 1-μm CMOS with two levels of metal and an additional mask level for fabricating capacitors. It contains both analog and digital circuits and has provisions for self-test. The function includes the transmitter, receiver, protocol handler, an microprocessor, as well as interfaces for RAM/ROM storage, IBM PC bus, IBM PS/2 bus, IBM 3174 bus, and Motorola 68000 bus. The physical design terrains are formed by 24K circuits of standard cell gates, a 10K-circuit equivalent hand-honed custom microprocessor, and an analog macro. The chip operates from a single 5-V supply, and the power consumption is 0.8 W nominal at 16 Mb/s. The chip can also be operated at 4 Mb/s 相似文献
4.
A family of differential latches has recently been proposed by Yuan and Svensson [1996]. The author shows that the proposed flip-flops using the dynamic slave latch suffer from a poor logic-level zero in the presence of glitches on the data inputs 相似文献
5.
Histogram measurement of ADC nonlinearities using sine waves 总被引:2,自引:0,他引:2
This paper gives results concerning the measurement of differential and integral nonlinearity of ADC's using the histogram method with a sine wave input signal. We specify the amount of overdrive required as a function of the noise level and the desired accuracy and the number of samples required as a function of the desired accuracy, the desired confidence level, and the noise level. An analysis of the effect on the results of harmonic distortion of the applied signal is given. The error analysis assumes a mixture of coherent and random sampling rather than pure random sampling 相似文献
6.
7.
Y Huang CA Macera SN Blair PA Brill HW Kohl JJ Kronenfeld 《Canadian Metallurgical Quarterly》1998,30(9):1430-1435
PURPOSE: A cohort of middle-aged and older men and women were followed for an average of 5.5 yr to examine the association between physical fitness, physical activity, and the prevalence of functional limitation. METHODS: The participants received medical assessments between 1980 and 1988 and responded to a mail-back survey regarding functional status in 1990. RESULTS: Among 3495 men and 1175 women over 40 yr of age at baseline, 350 (7.5%) reported at least one functional limitation in daily or household activities at follow-up. The prevalence of functional limitation was higher among women than men. Physically fit and physically active participants reported less functional limitation than unfit or sedentary participants. After controlling for age and other risk factors, the prevalence of functional limitation was lower for both moderately fit (odds ratio = 0.4, 95% CI = 0.2-0.6) and high fit men (odds ratio = 0.3, 95% CI = 0.2-0.4), compared with low fit men. Corresponding figures for women were 0.5 (0.3-0.7) and 0.3 (0.2-0.5) for moderately fit and high fit women. The association between physical activity and functional limitation was similar to the data for physical fitness. CONCLUSIONS: These data support a protective effect of physical fitness and physical activity on functional limitation among older adults and extend this protective effect to middle-aged men and women. 相似文献
8.
Arne Ketil Eidsvik Randi Karlsen Gordon Blair Paul Grace 《Journal of Computer and System Sciences》2008,74(2):158-169
Transaction execution in mobile environments needs to be flexible, not only to support typical mobile computing characteristics, like movement, disconnections and limited resources, but also to support the variety of transactional properties that might be required by different applications. Existing models for mobile transaction management solve different aspects of transaction execution, but are not flexible enough to solve all required aspects. Instead of designing a new transaction model, we propose a middleware (MobileTSe) which utilize existing transaction models to handle various requirements for mobile transaction execution. This paper presents an approach for flexible transaction processing in mobile applications, and describes how MobileTSe makes transaction services with different properties available on mobile units. We suggest a solution with transaction service discovery and control using UPnP. 相似文献
9.
Barrett CP Blair P Buller GS Neilson DT Robertson B Smith EC Taghizadeh MR Walker AC 《Applied optics》1996,35(35):6934-6944
We describe an optical system developed to form the basis of a 64 × 64 free-space optical matrix-matrix crossbar switch. The design and performance of each of the main optical components is discussed: lenses, diffractive optical elements, and polarizing beamsplitters, together with the optomechanical hardware design. For these components, throughput levels of -6.9 dB have been achieved, which is compatible with full system operation at 10(-12) bit error rates at ≥270 Mbits s(-1). 相似文献
10.
Models@ run.time 总被引:2,自引:0,他引:2
Runtime adaptation mechanisms that leverage software models extend the applicability of model-driven engineering techniques to the runtime environment. Contemporary mission-critical software systems are often expected to safely adapt to changes in their execution environment. Given the critical roles these systems play, it is often inconvenient to take them offline to adapt their functionality. Consequently, these systems are required, when feasible, to adapt their behavior at runtime with little or no human intervention. A promising approach to managing complexity in runtime environments is to develop adaptation mechanisms that leverage software models, referred to as models@run. time. Work on models@run.time seeks to extend the applicability of models produced in model-driven engineering (MDE) approaches to the runtime environment. Models@run. time is a causally connected self-representation of the associated system that emphasizes the structure, behavior, or goals of the system from a problem space perspective. 相似文献