全文获取类型
收费全文 | 812篇 |
免费 | 18篇 |
国内免费 | 11篇 |
专业分类
化学 | 31篇 |
力学 | 20篇 |
综合类 | 3篇 |
数学 | 40篇 |
物理学 | 19篇 |
综合类 | 728篇 |
出版年
2024年 | 5篇 |
2023年 | 6篇 |
2022年 | 6篇 |
2021年 | 11篇 |
2020年 | 9篇 |
2019年 | 1篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 6篇 |
2015年 | 13篇 |
2014年 | 35篇 |
2013年 | 45篇 |
2012年 | 54篇 |
2011年 | 76篇 |
2010年 | 79篇 |
2009年 | 124篇 |
2008年 | 49篇 |
2007年 | 38篇 |
2006年 | 37篇 |
2005年 | 35篇 |
2004年 | 33篇 |
2003年 | 24篇 |
2002年 | 18篇 |
2001年 | 22篇 |
2000年 | 12篇 |
1999年 | 18篇 |
1998年 | 13篇 |
1997年 | 10篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 4篇 |
1979年 | 1篇 |
排序方式: 共有841条查询结果,搜索用时 10 毫秒
21.
22.
从20世纪80年代中期到现在我国的幕墙行业突飞猛进,出于对建筑的外型美观的要求越来越高,对建筑物外墙装饰越来越重视。幕墙也经历了从有框玻璃幕墙、隐框玻璃幕墙、单元式玻璃幕墙,到现如今在较高标准建筑物外墙上使用的点驳接式幕墙的发展过程。分别对框式和点式玻璃幕墙施工中的关键技术进行简要介绍。 相似文献
23.
Xiang Pu Hanguang Wang Ping Zou Guangtu Wang Guizhou Yue Kuan Liu Li Cheng Juhua Feng Huixian Zhang Qianming Huang Hanbing Rao 《大学化学》1986,36(1):2002053-0
The crop science of Sichuan Agricultural University is an authorized first-class discipline. As the strategic supporting department for innovative talent cultivation in agriculture and forestry major, we are facing a long-term challenge in reforming the teaching mode for basic course-organic chemistry and cultivating talented students with solid basic knowledge and strong sense of innovation. Herein a thorough survey was performing to establish the executable teaching programs for this course during the "Double-First Class Universities Plan" period. A multidimensional teaching resource library for organic chemistry course was also constructed. The new classroom teaching mode "Interest cultivation-Creative thought development-Autonomous and Cooperative learning", along with a stepwise practice teaching mode "Foundation skills-Integrated application-Innovative trial" was proposed and practiced among thirty-five majors including agriculture, forestry and veterinary, to improve the quality for innovative talent cultivation and support our first-class discipline construction. This research could probably serve as a reference for congeneric agricultural university. 相似文献
24.
High-quality online course materials were reconstructed through feedback from undergraduate students and online data analysis regarding constructed learning materials on the Chao Xing Learning Platform. They were used for studying organic chemistry courses online and offline in university for nationalities. This model, based on student-centered teaching, can effectively transform students from passively accepting knowledge to actively learning and internalizing knowledge. This strategy can also enhance the students' learning initiative and the effects of learning, and hopefully be helpful to the universities in multi-ethnic areas in developing fundamental disciplined construction of organic chemistry and other courses. 相似文献
25.
We establish the construction theory of function based upon a local field K p as underlying space. By virture of the concept of pseudo-differential operator, we introduce fractal calculus(or, p-type calculus, or, Gibbs-Butzer calculus). Then, show the Jackson direct approximation theorems, Bermstein inverse approximation theorems and the equivalent approximation theorems for compact group D( Kp) and locally compact group K+p(= Kp), so that the foundation of construction theory of function on local fields is established. Moreover, the Jackson type, Bernstein type,and equivalent approximation theorems on the H ?lder-type space Cσ(Kp), σ 0, are proved; then the equivalent approximation theorem on Sobolev-type space Wrσ(Kp),σ≥ 0, 1 ≤ r +∞, is shown. 相似文献
26.
本文研究了一类由平面上点的表示系统所生成的内部非空的自相似集,证明其边界曲线的一半是三个A-完备集的并集,并给出计算这类完备集的结构矩阵的简单方法,从而利用Marion定理得出这类自相似集边界的Hausdorff维数。 相似文献
27.
28.
Self-dual codes over exist for all even lengths. The smallest length for which the largest minimum weight among self-dual codes has not been determined
is 24, and the largest minimum weight is either 9 or 10. In this note, we show that there exists no self-dual [24, 12, 10]
code over , using the classification of 24-dimensional odd unimodular lattices due to Borcherds.
相似文献
29.
30.
Effective routing of vehicles remains a focal goal of all modern enterprises, thriving for excellence in project management with minimal investment and operational costs. This paper proposes a metaheuristic methodology for solving a practical variant of the well-known Vehicle Routing Problem, called Heterogeneous Fixed Fleet VRP (HFFVRP). Using a two-phase construction heuristic, called GEneralized ROute Construction Algorithm (GEROCA), the proposed metaheuristic approach enhances its flexibility to easily adopt various operational constraints. Via this approach, two real-life distribution problems faced by a dairy and a construction company were tackled and formulated as HFFVRP. Computational results on the aforementioned case studies show that the proposed metaheuristic approach (a) consistently outperforms previous published metaheuristic approaches we have developed to solve the HFFVRP, and (b) substantially improves upon the current practice of the company. The key result that impressed both companies’ management was the improvement over the bi-objective character of their problems: the minimization of the total distribution cost as well as the minimization of the number of the given heterogeneous number of vehicles used. 相似文献