全文获取类型
收费全文 | 766篇 |
免费 | 220篇 |
国内免费 | 17篇 |
出版年
2023年 | 6篇 |
2022年 | 19篇 |
2021年 | 41篇 |
2020年 | 17篇 |
2019年 | 10篇 |
2018年 | 9篇 |
2017年 | 19篇 |
2016年 | 10篇 |
2015年 | 37篇 |
2014年 | 33篇 |
2013年 | 46篇 |
2012年 | 38篇 |
2011年 | 39篇 |
2010年 | 48篇 |
2009年 | 47篇 |
2008年 | 37篇 |
2007年 | 50篇 |
2006年 | 27篇 |
2005年 | 35篇 |
2004年 | 13篇 |
2003年 | 14篇 |
2002年 | 6篇 |
2001年 | 12篇 |
2000年 | 25篇 |
1999年 | 48篇 |
1998年 | 50篇 |
1997年 | 39篇 |
1996年 | 40篇 |
1995年 | 30篇 |
1994年 | 32篇 |
1993年 | 25篇 |
1992年 | 17篇 |
1991年 | 24篇 |
1990年 | 21篇 |
1989年 | 11篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 5篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有1003条查询结果,搜索用时 15 毫秒
931.
932.
谈谈军工企业自主创新中知识产权的管理 总被引:1,自引:0,他引:1
介绍了军工企业单位自主创新中知识产权管理现状、存在的问题以及知识产权管理的意义,探讨了研究开发中知识产权利用和管理的方法、模式。 相似文献
933.
934.
Many manufacturers sell their products through retailers and share the revenue with those retailers. Given this phenomenon, we build a stylized model to investigate the role of revenue sharing schemes in supply chain coordination and product variety decisions. In our model, a monopolistic manufacturer serves two segments of consumers, which are distinguished by their willingness to pay for quality. In the scenario with exogenous revenue sharing ratios, when the potential gain from serving the low segment is substantial (e.g., the low‐segment consumers' willingness to pay is high enough or the low segment takes a large enough proportion of the market), the retailer is better off abandoning the revenue sharing scheme. Moreover, when the potential gain from serving the low (high) segment is substantial enough, the manufacturer finds it profitable to offer a single product. Furthermore, when revenue sharing ratios are endogenous, we divide our analysis into two cases, depending on the methods of cooperation. When revenue sharing ratios are negotiated at the very beginning, the decentralized supply chain causes further distortion. This suggests that the central premise of revenue sharing—the coordination of supply chains—may be undermined if supply chain parties meticulously bargain over it. 相似文献
935.
We consider scheduling a set of jobs with deadlines to minimize the total weighted late work on a single machine, where the late work of a job is the amount of processing of the job that is scheduled after its due date and before its deadline. This is the first study on scheduling with the late work criterion under the deadline restriction. In this paper, we show that (i) the problem is unary NP‐hard even if all the jobs have a unit weight, (ii) the problem is binary NP‐hard and admits a pseudo‐polynomial‐time algorithm and a fully polynomial‐time approximation scheme if all the jobs have a common due date, and (iii) some special cases of the problem are polynomially solvable. 相似文献
936.
为了解决传统的自适应均衡技术需发送训练序列的问题,采用盲均衡技术,利用接收信号本身的特征使均衡器收敛。提出了一种新的盲均衡算法(C&D算法),该算法将CRIMNO算法和判决引导(Decision Directed,DD)算法相结合,利用信号序列间的互不相关特性,从而使其具有全局收敛性能。实验结果表明:与CRIMNO算法相比,在相同的信噪比下,该算法具有收敛快速、运算量少和残留误差小的特点。 相似文献
937.
双天线激励混响室场均匀性研究 总被引:1,自引:0,他引:1
采用电磁仿真软件FEKO分别建立单、双天线激励混响室仿真模型,通过计算混响室测试区域电场标准偏差值研究混响室场均匀性。研究表明:与单天线激励混响室相比较,混响室工作于双天线激励条件时,测试区域各轴向电场标准偏差平均下降了15.3%,总标准偏差下降了21.9%,改善了测试区域场均匀性,这说明双天线激励混响室可提高场均匀性,同时利用双天线的功率合成解决了混响室大功放问题。 相似文献
938.
复杂战争系统建模与仿真需求及ABMS方法 总被引:1,自引:1,他引:0
复杂战争系统与一般的物理系统相比,建模与仿真条件、要求与过程有着明显差异。在论述战争系统及其复杂性的基础上,分析了复杂战争系统一般的建模与仿真方法及存在的问题,重点分析研究了基于Agent的建模与仿真(ABMS)方法。将ABMS方法应用于信息化战场多传感器仿真演示,验证了其对复杂战争系统建模与仿真的可行性与有效性。 相似文献
939.
Reliability data obtained from life tests and degradation tests have been extensively used for purposes such as estimating product reliability and predicting warranty costs. When there is more than one candidate model, an important task is to discriminate between the models. In the literature, the model discrimination was often treated as a hypothesis test and a pairwise model discrimination procedure was carried out. Because the null distribution of the test statistic is unavailable in most cases, the large sample approximation and the bootstrap were frequently used to find the acceptance region of the test. Although these two methods are asymptotically accurate, their performance in terms of size and power is not satisfactory in small sample size. To enhance the small‐sample performance, we propose a new method to approximate the null distribution, which builds on the idea of generalized pivots. Conventionally, the generalized pivots were often used for interval estimation of a certain parameter or function of parameters in presence of nuisance parameters. In this study, we further extend the idea of generalized pivots to find the acceptance region of the model discrimination test. Through extensive simulations, we show that the proposed method performs better than the existing methods in discriminating between two lifetime distributions or two degradation models over a wide range of sample sizes. Two real examples are used to illustrate the proposed methods. 相似文献
940.
近代中国留日陆军士官生人数考究 总被引:1,自引:0,他引:1
据笔者所看到的资料,关于近代中国留日陆军士官生的人数,常出现不一致,而留日陆军士官生在近代中国的地位与作用日益得到学术界的关注。所以,本文拟从相关史料的来源、人数统计所要说明的一些特殊情况和其人数变化所反映的中日关系等方面进行梳理与考证。 相似文献