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911.
912.
A GPSS/360 model was developed to investigate the behavior of a university's motor pool dispatch fleet. Time-series data were collected and frequency distributions were constructed for vehicle request patterns and trip-duration times. Regression analysis was performed to formulate trip mileage generators as functions of service time. Appropriate statistical goodness-of-fit tests were conducted to ascertain the extent of congruence between actual system behavior and expectations based on a number of theoretical distributions. Analysis of simulated response variables indicates that the model's internal structure reproduces reality to a high degree. Fifteen years of simulated experience were generated for six alternative fleet size configurations; results suggest that reductions in existing fleet capacity could be realized without effecting undue impairment in service levels. 相似文献
913.
Daniel J. Andrews Timothy L. Eddy Kelsey S. Hollenback Shravan Sreekumar Davis C. Loose Cody A. Pennetti Thomas L. Polmateer James C. Haug Lessie I. Oliver-Clark Joi Y. Williams Mark C. Manasco Steven Smith James H. Lambert 《Risk analysis》2023,43(4):820-837
Real-time tracking of tool and equipment inventories is a critical function of many organizations and sectors. For prisons and correctional facilities, tracking and monitoring of assets such as cookware, hardware, keys, janitorial equipment, vocational/technical specialty tools, etc., is essential for safety, security, trust, efficiency, education, etc. The performance of automated systems for this purpose can be diminished by a variety of emergent and future sociotechnical factors alone and in combination. This article introduces a methodology for contractor evaluation and selection in acquisition of innovative asset management systems, with an emphasis on evolving system requirements under uncertainty. The methodology features a scenario-based preferences analysis of emergent and future conditions that are disruptive to the performance of the asset-control system. The conditions are across technologies, operating environments, regulations, workforce behaviors, offender behaviors, prices and markets, organizations, cyber threats, etc. The methodology addresses the influence and interaction of the conditions to disrupt system priorities. Examples include: (i) infectious disease disrupting priorities among requirements and (ii) radio-frequency identification (RFID) and wireless-technology innovations disrupting priorities among stakeholders. The combinations of conditions that most and least matter for the system acquisition are characterized. The methodology constitutes a risk register for monitoring sources of risk to project performance, schedule, and cost throughout the system lifecycle. The results will be of interest to both practitioners and scholars engaged in systems acquisition as the pandemic interacts with other factors to affect risk, uncertainty, and resilience of organizational missions and operations. 相似文献
914.
This paper demonstrates how qualitative analysis can be a novel means of investigating theories of error and causation in natural gas pipeline incidents. Qualitative analysis offers unique opportunities to understand process, interactions, and the role of context in identifying active error and latent conditions in incident causation. Through the coding of text from 24 onshore natural gas pipeline incident reports on leaks and explosions in the United States and Canada, our findings reveal a proportion of active and latent errors consistent with other hazardous infrastructure contexts (roughly 3:1 latent-active ratio across 817 coded errors). These findings underscore the robustness of extant error theory and support the argument for documenting multiple, connected causes of disaster in aggregate. Conclusions highlight the utility of in-depth case analyses and critique present pipeline incident database aggregation. Our interpretation provides a means to convey complex causation in aggregate form thus enabling more nuanced future qualitative and qualitative analyses. 相似文献
915.
When young people are sexually exploited, parents and professionals alike can feel uncertain about how to balance the need to protect the child's rights to agency and autonomy while also reducing the risk of harm. Despite the shared interest in keeping young people safe, there remains a substantial gap in the research literature about how practitioners engage parents to increase capacity to safeguard their children, particularly within the context of a child protection system ill-equipped to address forms of extrafamilial harm such as child sexual exploitation. This paper aims to contribute to understanding how professionals effectively engage parents by drawing upon evidence from research evaluations of two programmes in rural/urban North and urban South locations in England, both providing specialist support to parents/carers of sexually exploited children and young people. Through interrogating elements of effective support work evidenced across both programmes, a set of emerging key themes are presented, proposing that parent support and engagement can create a ‘virtuous’ cycle, whereby families are strengthened and are better able to protect their children from sexual exploitation and other forms of extrafamilial harm. 相似文献
916.
917.
Elliott F. Williams Süleyman Tüfekcli Mehmet Akansel 《Production and Operations Management》1997,6(1):74-96
Lot streaming is the process of splitting a job or lot into sublots to reduce its makespan on a sequence of machines. The goal in the lot streaming problem is to find the optimal size of each sublot that will minimize the makespan. The makespan is defined as the time the last sublot completes its processing on the last machine. If the sizes of these sublots are restricted to remain the same on all machines, the solution is called a consistent sublot solution. However, if the sizes of the sublots are allowed to vary, the solution is referred to as a nonconsistent or variable sublot solution. Also, if the machines must be in operation continuously from the first to the last sublot, the solution is a no idling solution. When setups are explicitly considered in the problem, there will be two cases. If setups on each machine require some portion of the first sublot be present by the machine, the problem is referred to as the attached setup time problem. If setups can be performed ahead of time before the first sublot reaches the particular machine, the corresponding problem is referred to as the detached setup problem. Finally, if the machines are allowed to be idle between the processing of sublots, the resultant solution is an intermittent idling solution. In this paper, the consistent sublot lot streaming problem with intermittent idling and no setups is discussed. The models developed also assume that the number of sublots are fixed and known. The m machine two sublot lot streaming problem is reviewed. An algorithm for the three sublot, m machine problem is derived using a network representation of the problem. The complexity of the algorithm is O (m2). Finally, using the insights from three sublot problem, a heuristic algorithm is provided for the m machine, n sublot problems. The results on the proposed heuristic are very encouraging; average percent deviation from optimal makespan is approximately at 0.76% on 155 randomly generated problems with different m and n values. 相似文献