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101.
已有的半脆弱水印算法大多数采取了双步长的固定量化方法,对载体图像没有针对攻击特性给予考虑,只将载体图像分为平滑和纹理两个区域,使得水印的鲁棒性进入了一个瓶颈状态。为了进一步提高水印的鲁棒性,提出了一种基于图像动态分割技术和信息熵的半脆弱水印算法。图像动态分割技术将图像分为若干个嵌入区域,并且确定各个嵌入区域的嵌入强度;基于信息熵的步长量化算法将信息熵引入到步长量化的计算方法中,能够有效衡量不同嵌入区域所携带的敏感信息量。实验结果表明,提出的算法与已有半脆弱水印算法相比,视觉掩蔽性好,鲁棒性也有了较明显的提高。 相似文献
102.
Robert J. Marley Michelle R. Thomson 《International Journal of Industrial Ergonomics》2000,25(6):1441-643
A laboratory experiment was conducted to measure strength characteristics in dynamic (isokinetic) wrist flexion and extension. Twenty four college-age males exerted their maximum torque in both concentric flexion and extension at 60, 120, and 180°/s of angular velocity through a ±60° range of deviation from wrist neutral. Results show that velocity and motion direction significantly effected both peak torque as well as the postural displacement of peak torque. The value of peak torque decreased with an increase in velocity and the wrist angle at peak torque generally moved to a more deviated, flexed posture (from neutral) with increasing velocity as well. Peak torque for all velocity and motion-type conditions tested occurred in a flexed posture relative to neutral. It is anticipated that these results may be of use as biomechanically based considerations in the evaluation and design of upper extremity tasks involving wrist flexion/extension as well as to perhaps give insight into functional characteristics of the wrist. Finally, regression equations were developed to aid in the prediction of peak torque based upon task, individual and/or population parameters.
Relevance to industry
Results from this study should enhance the overall understanding of wrist functioning. Specifically, motion type, velocity of movement and wrist posture are important ergonomic design considerations. These results can also be used to modify existing biomechanical models that do not consider wrist variables. 相似文献
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本文叙述了一种适合大型氨厂使用的、堆密度低到1.25 kg·L-1、还原态侧压强度高达350 N·cm-1以上、本体含硫<500 ppm(wt)、低温活性好的高温变换催化剂的研制开发过程 还介绍了催化剂制备工艺特点和工业试用效果。 相似文献
106.
《Ergonomics》2012,55(12):1996-2015
Experiments were designed to investigate the effects of control type and display location, relative to the operator, on the strength of control/display stereotypes. The Worringham and Beringer Visual Field principle and an extension of this principle for rotary controls (Hoffmann E.R., and Chan A.H.S. 2013). “The Worringham and Beringer ‘Visual Field’ Principle for Rotary Controls. Ergonomics.” 56 (10): 1620–1624) indicated that, for a number of different control types (rotary and lever) on different planes, there should be no significant effect of the display location relative to the seated operator. Past data were surveyed and stereotype strengths listed. Experiments filled gaps where data are not available. Six different control types and seven display locations were used, as in the Frame of Reference Transformation Tool (FORT) model of Wickens et al. (Wickens, C.D., Keller, J.W., and Small, R.L. (2010). “Left. No, Right! Development of the Frame of Reference Transformation Tool (FORT).” Proceedings of the Human Factors and Ergonomics Society 54th Annual Meeting September 2010, 54: 1022–1026). Control/display arrangements with high stereotype strengths were evaluated yielding data for designers of complex control/display arrangements where the control and display are in different planes and for where the operator is moving. It was found possible to predict display/control arrangements with high stereotype strength, based on past data.Practitioner Summary: Controls and displays in complex arrangements need to have high compatibility. These experiments provide arrangements for six different controls (rotary and translational) and seven different display locations relative to the operator. 相似文献
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《Ergonomics》2012,55(7):1096-1108
Farm tractors account for the majority of fatal injuries to adolescents working in agriculture and therefore remain a leading occupational priority. The question of whether these injuries occur because adolescents are assigned tractor jobs beyond their physical capabilities has not been answered. The purpose of this study was to estimate the activation forces required to operate controls on 40 tractors in common use in the US and compare them with existing estimates of physical strength for children of varying ages and with recommended ergonomic force limits for repeatedly engaging controls. Activation forces for steering, brakes and clutch were measured on each tractor. The main study finding was that the activation forces required to operate tractors typically exceeded the physical abilities of most children aged 13 to 17 years. This raises serious questions about the ability of children to safely operate tractors in common use on US farms. This study provides an ergonomic approach for evaluating the potential mismatch between young people's strength capabilities and forces required in operating farm tractors. This approach could be used in similar situations where adolescents may operate vehicles (e.g. all-terrain vehicles), machinery or other mechanical devices requiring activation of levers and controls. Study findings potentially inform the establishment of occupational policies surrounding tractor operation by young people. 相似文献
110.
With the development of Compressive Sensing theory in recent years, many new algorithms have been introduced to this field. But still, these algorithms tend to judge the probability of the nonzero signal in each position of the sparse domain as the same, which is in fact not true. In this topic we discuss orthogonal coefficient distribution and divide the whole sparse domain into different parts using probability. With the method called Sparse domain Division using Probability (SDP), the reconstructed speed would increase 20~60 times without producing any negative effect on image quality at the same sampling rate. 相似文献