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91.
Amos Zemel Israel David & Abraham Mehrez 《International Transactions in Operational Research》2001,8(5):585-601
We consider development projects in which the activities can be classified in two types: uncertainty resolving R&D efforts that accumulate in the form of knowledge to eventually give rise to a discovery; and routine technical investments which aim at improving the profitability of the project once the discovery has been made. The advantage of initiating routine preparatory activities prior to the achievement of a technological breakthrough in such projects, sometimes termed as 'concurrent engineering', is analyzed within a suitable dynamic optimization framework. The optimal double expenditure policy is compared with the conservative delayed investment policy, under which all the routine engineering activities are delayed until the risky R&D efforts culminate in a breakthrough. A criterion for the optimality of the latter policy is developed on the basis of the probability distribution of the discovery date. The application of the criterion is illustrated for a variety of specifications regarding the uncertainty associated with the R&D process. We find that simultaneous investment is the optimal policy for a large class of probability distributions. However, if the conditional probability of immediate discovery is always below some critical value, it is optimal to delay the preparatory activities until the discovery. 相似文献
92.
基于资源约束的并行活动优化调度方法 总被引:4,自引:0,他引:4
针对并行产品开发过程,提出了一种基资源约束的优化调度算法,首先给出了并行活动的三个定义,提出了一个使算法能够实现优化调度的综合函数,并研究了并行工程中的两个关键问题--角色分配和反馈修改,仿真实例表明了算法的可行性。 相似文献
93.
提出一种基于约束网络的鲁棒设计方法,该方法能用约束网络对并行设计中的一类不确定性参数进行有效的描述和处理。提出了反映该问题需求的数学模型,设计了通用的一致性求解算法框架,得到了满足该框架的算法都是弧一致的充分条件以及推论,并利用区间算法对该框架进行实现。飞行器布局设计实例说明了该方法的有效性。 相似文献
94.
针对并行设计中冲突协商策略的选取和优化解的非唯一性问题,给出了冲突的数学描述形式以及冲突原因的数学解释,证明了合作策略的优越性,研究了基于Nash定理的冲突协商解的存在性和唯一性,并给出一种协商模型以及具体应用实例. 相似文献
95.
96.
一种并发PASCAL语言的设计与实现 总被引:2,自引:2,他引:0
本文论述了作者设计的一种并发PASCAL语言,语言中采用了作者提出的“可更换式进程调度”思想,使本语言不但能满足不同用户对调度策略的需求,同时还可以使本系统开销保持在很低的水平.“可更换式进程调度”的含义是:在并发PASCAL语言的进程调度中,不是采用传统的固定的调度算法模式,而是允许程序员按照不同需求,使用不同算法的进程调度内核程序. 相似文献
97.
A longitudinal assessment of the introduction of new office technologies into a multinational bank was conducted using both task diaries and semi-structured interviews. Task diaries were administered prior to the introduction of microcomputers, several months after the introduction and several years later. Semi-structured interviews were completed after the second task diary. The assessment provides evidence of how offices adapt to changing electronic tookits. The asssessment provides ergonomists with a usable list of taks activities and the effects on task variability of the adoption of microcomputers into the work routine. It shows that when support staff are asked to use a new computer they must choose what other tasks to cut back on, which has consequences for the overall work process. Overtime increased 170% after the introduction of the computer. In a culture where professional staff have high expectations of support staff this has consequences for working relationships in terms of perceptions of the computer's utility. Support staff and professional staff differ in perceptions of control, time-saving and ability to make corrections. The assessment demonstrates the importance of multiple measurement instruments in tracking the effects of technological change on the work process. In conclusion, it is noted that the introduction of new technologies into the office must be considered in the broader office context to avoid the unintended consequences often reported in other case studies. 相似文献
98.
Drury CG 《Applied ergonomics》1983,14(1):19-28
Task analysis is one of the basic tools used by ergonomists in investigating and designing tasks. It provides a formal comparison between the demands which the task places on the human operator and the capabilities the human operator possesses to deal with these demands. Three types of task analysis are described: sequential, branching and process control. Alternative formats are presented and examples given of their use in an industrial setting. 相似文献
99.
Qiuling Zou Qinghong Zhang Jingzhou Yang Aimee Cloutier Esteban Pena-Pitarch 《Computers & Industrial Engineering》2012
This paper presents a nonlinear inverse optimization approach to determine the weights for the joint displacement function in standing reach tasks. This inverse optimization problem can be formulated as a bi-level highly nonlinear optimization problem. The design variables are the weights of a cost function. The cost function is the weighted summation of the differences between two sets of joint angles (predicted posture and the actual standing reach posture). Constraints include the normalized weights within limits and an inner optimization problem to solve for joint angles (predicted standing reach posture). The weight linear equality constraints, obtained through observations, are also implemented in the formulation to test the method. A 52 degree-of-freedom (DOF) human whole body model is used to study the formulation and visualize the prediction. An in-house motion capture system is used to obtain the actual standing reach posture. A total of 12 subjects (three subjects for each percentile in stature of 5th percentile female, 50th percentile female, 50th percentile male and 95th percentile male) are selected to run the experiment for 30 tasks. Among these subjects one is Turkish, two are Chinese, and the rest subjects are Americans. Three sets of weights for the general standing reach tasks are obtained for the three zones by averaging all weights in each zone for all subjects and all tasks. Based on the obtained sets of weights, the predicted standing reach postures found using the direct optimization-based approach have good correlation with the experimental results. Sensitivity of the formulation has also been investigated in this study. The presented formulation can be used to determine the weights of cost function within any multi-objective optimization (MOO) problems such as any types of posture prediction and motion prediction. 相似文献
100.
This paper considers the problem of multirobot coordination in pick-and-place tasks on a conveyor band. The robot team is composed of identical robots with mutually exclusive, but neighboring workspaces. The products are fed in at one end of the band, move through each workspace sequentially until being picked up and are collected at the other end—if not picked up interim. Each robot has the same task—that is picking up and packaging as many products as possible. We propose an approach based on noncooperative game theory where each robot uses local observations of the conveyor band and their neighbors' actions in order to decide on its actions. The developed algorithm has been implemented and tested in a simulated manufacturing environment using Webots. Results obtained from the simulations are analyzed using a variety of statistical performance measures. 相似文献