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974.
When raw material suppliers of a global supply chain are situated in developing countries, not only will there be long lead times but there could also be a possibility of material losses in transit. The magnitude of the losses will be uncertain and can be significant. We consider the optimization of order quantity decisions in such situations. The long lead times imply that we need to take into account the uncertainty in finished goods demands for which the raw materials are to be ordered. The order quantities have to be optimized carefully as they determine the “real options” that become available later in production plans. Using data from the plywood industry and using stochastic programming we demonstrate a method for solving such problems. The method combines simulation and optimization. An interesting observation we make is that the optimal order quantity of a material need not be monotonic in expected loss of that material. In addition, we offer explanations as to why the expected loss need not be monotonic. 相似文献
975.
A reduction in the inventory replenishment lead-time allows reducing safety stock requirements and improving customer service. However, it might be accompanied by increased procurement costs because of premium charges imposed by suppliers, or higher transportation costs. This paper studies a single-stage variable lead-time inventory system with lead-time dependent procurement cost. Selection of the lead-time value represents finding the trade-off between benefits of lead-time reduction and increase in the procurement cost. A model for joint optimization of inventory and procurement costs is developed. Numerical studies are conducted to identify conditions under which lead-time reduction is favorable compared to procuring at the lowest cost. 相似文献
976.
考虑交通网络中实现用户均衡态的过程,引入决策出行费用的概念,提出一个 ATIS 环境下的交通配流动态演化模型,模型中的 OD 需求是可变内生的.利用稳定性定理分析了该动态系统的稳定性,说明在一定条件下,系统的用户均衡态是稳定的.采用改进的欧拉法完成了模型的数值试验,结果表明该动态系统确实可以达到用户均衡态,同时也发现,某些模型参数的变化可能导致路径流量和 OD 费用演化轨迹的无规则摆动. 相似文献
977.
We examine optimal control decisions regarding pricing, network size, and hiring strategy in the context of open source software development. Opening the source code to a software product often implies that consumers would not pay for the software product itself. However, revenues may be generated from complementary products. A software firm may be willing to open the source code to its software if it stands to build a network for its complementary products. The rapid network growth is doubly crucial in open source development, in which the users of the firm's products are also contributors of code that translates to future quality improvements. To determine whether or not to open the source, a software firm must jointly optimize prices for its various products while simultaneously managing its product quality, network size, and employment strategy. Whether or not potential gains in product quality, network size, and labor savings are sufficient to justify opening the source code depends on product and demand characteristics of both the software and the complementary product, as well as on the cost and productivity of in‐house developers relative to open source contributors. This paper investigates these crucial elements to allow firms to reach the optimal decision in choosing between the open and closed source models. 相似文献
978.
Technologies such as radio‐frequency identification and global positioning systems can provide improved real‐time tracking information for products and replenishment orders along the supply chain. We call this type of visibility order progress information. In this paper, we investigate how order progress information can be used to improve inventory replenishment decisions. To this end, we examine a retailer facing a stochastic lead time for order fulfillment. We characterize a replenishment policy that is based on the classical (Q, R) policy and that allows for releasing emergency orders in response to the order progress information. We show that the optimal structure of this policy is given by a sequence of threshold values dependent on order progress information. In a numerical study we evaluate the cost savings due to this improved replenishment policy. 相似文献
979.
Hyun‐cheol Paul Choi James D. Blocher Srinagesh Gavirneni 《Production and Operations Management》2008,17(6):614-625
New developments in corporate information technology such as enterprise resource planning systems have significantly increased the flow of information among members of supply chains. However, the benefits of sharing information can vary depending on the supply chain structure and its operational characteristics. Most of the existing research has studied the impact of sharing downstream information (e.g., a manufacturer sharing information with its suppliers). We evaluate the benefits of sharing upstream yield information (e.g., a supplier sharing information with the manufacturer) in a two‐stage serial supply chain in which the supplier has multiple internal processes and is faced with uncertain output due to yield losses. We are interested in determining when the sharing of the supplier's information is most beneficial to the manufacturer. After proposing an order‐up‐to type heuristic policy, we perform a detailed computational study and observe that this information is most beneficial when the supplier's yield variance is high and when end‐customer demand variance is low. We also find that the manufacturer's backorder‐to‐holding cost ratio has little, if any, impact on the usefulness of information. 相似文献
980.
Agnes Meershoek 《Social Policy & Administration》2012,46(5):544-561
Policymakers in industrialized countries attempt to contain the costs of sick leave and disability schemes by limiting access to include medically proven cases only. However, a person's incapacity to work cannot be fully deduced by referring to his or her medical condition. It is the question whether using more restrictive eligibility criteria that focus on medical evidence actually reduces the number of benefit recipients and makes access to employee benefit arrangements fairer. This ethnographic study shows that physicians working in Dutch illness certification practices use alternative methods to restrict access to sick leave programmes. Doctors do not control their clients in a restrictive sense of the word. Rather, they exercise control over their clients by inciting them to internalize norms about being active and responsible. While we do not claim that this is good per se, we do contend that this control style may have some advantages over and above more restrictive control mechanisms. Elaborating on policy that supports this alternative notion of control, therefore, seems worthwhile. 相似文献