全文获取类型
收费全文 | 59542篇 |
免费 | 1568篇 |
国内免费 | 2413篇 |
专业分类
系统科学 | 2186篇 |
丛书文集 | 2157篇 |
教育与普及 | 2246篇 |
理论与方法论 | 281篇 |
现状及发展 | 331篇 |
研究方法 | 214篇 |
综合类 | 56097篇 |
自然研究 | 11篇 |
出版年
2024年 | 216篇 |
2023年 | 759篇 |
2022年 | 1000篇 |
2021年 | 1069篇 |
2020年 | 715篇 |
2019年 | 253篇 |
2018年 | 456篇 |
2017年 | 611篇 |
2016年 | 559篇 |
2015年 | 1251篇 |
2014年 | 1781篇 |
2013年 | 1606篇 |
2012年 | 1890篇 |
2011年 | 2189篇 |
2010年 | 2033篇 |
2009年 | 2499篇 |
2008年 | 2875篇 |
2007年 | 2760篇 |
2006年 | 2100篇 |
2005年 | 2127篇 |
2004年 | 1672篇 |
2003年 | 1391篇 |
2002年 | 1409篇 |
2001年 | 1604篇 |
2000年 | 1772篇 |
1999年 | 3210篇 |
1998年 | 3013篇 |
1997年 | 3140篇 |
1996年 | 2813篇 |
1995年 | 2445篇 |
1994年 | 2326篇 |
1993年 | 2005篇 |
1992年 | 1725篇 |
1991年 | 1528篇 |
1990年 | 1324篇 |
1989年 | 1181篇 |
1988年 | 982篇 |
1987年 | 628篇 |
1986年 | 358篇 |
1985年 | 134篇 |
1984年 | 34篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1979年 | 5篇 |
1977年 | 4篇 |
1975年 | 5篇 |
1974年 | 6篇 |
1973年 | 6篇 |
1970年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 23 毫秒
11.
通过post李超代数的定义, 讨论post李超代数结构的基本性质, 给出post李超代数的一些存在性结果, 并利用post李超代数可构造LR超代数和左对称超代数, 给出交换post李超代数结构的相关结果. 相似文献
12.
Study on the Centralization Strategy of the Blood Allocation Among Different Departments within a Hospital 总被引:1,自引:1,他引:0
By far, the researches on how to distribute blood products among different departments in hospital have not been further studied, though the problem of blood shortage and wastage that caused by improper blood allocation is severe, which may endanger patient’s lives and impose considerable costs on hospitals. In order to solve this problem, this paper mainly studies on how to distribute the blood items among different departments within a hospital and investigates the allocation approach with the novel management method by centralizing the inventory of several different departments. By integrating the blood inventory requirements of some departments, the hospital could reduce the rate of blood shortage and wastage effectively, release the pressure of the occupancy of resources and reduce the bullwhip effect of blood products. This paper illustrates the centralization principle in hospital and formulates the mixed integer programming model to work out the optimal allocation network scheme and the optimal inventory setting for every department. And the results of the numerical example demonstrate that this centralization method could considerably reduce blood shortage and wastage in hospital by about 72% and 90% respectively. Furthermore, it could decrease the total cost by about 108,540 RMB a month on blood supply chain management in the hospital and improve the effect of some certain surgeries by transfusing the fresh blood to patients. 相似文献
13.
In this paper, views of investor are described in fuzzy sets, and two fuzzy Black-Litterman models are constructed with fuzzy views and fuzzy random views respectively. In the models, expected returns and uncertainty matrix of views are redefined and the views are formulated by fuzzy approaches suitably. Then the models are tested with data from Chinese financial markets. Empirical results show that the fuzzy random views model performs the best, and both the fuzzy models are better than the traditional ones, demonstrating that the fuzzy approaches can contain more information in the views and measure the uncertainty more correctly. 相似文献
14.
近年来,我国农民工群体正处在代际更替的阶段,新生代农民工有其独特的消费观念、消费结构和消费行为。同时,新生代农民工也面临生产生活方式和消费方式的变化,其收入提高与消费行为转变更是实现我国经济转型的重要推动力。基于此,本文选取郑州市作为样本地区,对新生代农民工的收入状况、消费观念和消费行为进行实地调查,运用Logist模型分析其收入状况、消费观念对其消费行为选择的影响。最后,从改善新生代农民工收入状况、人力资本提升和消费观念的引导等方面提出科学、合理的建议。 相似文献
15.
De Casteljau algorithm and degree elevation of Bézier and NURBS curves/surfaces are two important techniques in computer aided geometric design. This paper presents the de Casteljau algorithm and degree elevation of toric surface patches, which include tensor product and triangular rational Bézier surfaces as special cases. Some representative examples of toric surface patches with common shapes are illustrated to verify these two algorithms. Moreover, the authors also apply the degree elevation of toric surface patches to isogeometric analysis. And two more examples show the effectiveness of proposed method. 相似文献
16.
Journal of Systems Science and Complexity - The GVW algorithm is an efficient signature-based algorithm for computing Gröbner bases. In this paper, the authors consider the implementation of... 相似文献
17.
18.
A synthesis method for global stability and performance of input constrained linear systems, which uses a linear outputfeedback controller and a static anti-windup compensator is investigated. Different from the traditional two-step anti-windup design procedure, the proposed method synthesizes all controller parameters simultaneously. Sufficient conditions for global stability and minimizing the induced L2 gain are formulated and solved as a linear matrix inequalities(LMIs) optimization problem, which also provides an opportunity to search for a better performance tradeoff between the linear controller and the anti-windup compensator.The well-posedness of the close-loop system is also guaranteed.Simulation results show the effectiveness of the proposed method. 相似文献
19.
20.