全文获取类型
收费全文 | 279篇 |
免费 | 10篇 |
国内免费 | 1篇 |
专业分类
化学 | 193篇 |
力学 | 18篇 |
数学 | 45篇 |
物理学 | 34篇 |
出版年
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 8篇 |
2020年 | 22篇 |
2019年 | 21篇 |
2018年 | 20篇 |
2017年 | 20篇 |
2016年 | 21篇 |
2015年 | 11篇 |
2014年 | 23篇 |
2013年 | 28篇 |
2012年 | 18篇 |
2011年 | 20篇 |
2010年 | 13篇 |
2009年 | 12篇 |
2008年 | 7篇 |
2007年 | 8篇 |
2006年 | 6篇 |
2005年 | 10篇 |
2004年 | 5篇 |
2003年 | 4篇 |
2002年 | 2篇 |
1997年 | 1篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1977年 | 1篇 |
1976年 | 2篇 |
1970年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有290条查询结果,搜索用时 687 毫秒
71.
72.
Behzad Zeynizadeh Karim Akbari Dilmaghani Mahdi Yari 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):2465-2471
One-pot cyclocondensation reaction of aromatic aldehydes, 1,3-dicarbonyl compounds and urea/thiourea in the presence of NaHSO4·H2O produced 4-aryl substituted 3,4-dihydropyrimidin-2(1H)-ones and their sulfur analogs in high to excellent yields. The reactions were carried out in refluxing n-hexane and were completed within 2.5–11 h. 相似文献
73.
Behzad Zeynizadeh Samal Yeghaneh 《Phosphorus, sulfur, and silicon and the related elements》2013,188(2):362-368
Structurally different epoxides were efficiently converted to the corresponding thiiranes by Dowex-50WX8–supported thiourea under solvent-free conditions. The reactions were carried out either in an oil bath or under microwave irradiation to give the thiiranes in 75–98% yields within 30 sec–120 min. 相似文献
74.
75.
Hari M. Srivastava Hatira Günerhan Behzad Ghanbari 《Mathematical Methods in the Applied Sciences》2019,42(18):7210-7221
The main aim of this article is to present some new exact solutions of the resonant nonlinear Schrödinger equation. These solutions are derived by using the generated exponential rational function method (GERFM). The kink‐type, bright, dark, and singular soliton solutions are reported, and several numerical simulations are also included. The calculations are carried out by Maple software. All of the solutions that are derived in this paper are believed to be new and have presumably not been reported in earlier publications. 相似文献
76.
Ionics - A simple and rapid electrochemical method developed for the detection of trace amounts of morphine (MO) at the surface of modified pencil graphite electrode (PGE) with multiwall carbon... 相似文献
77.
Arash?KhatibiEmail author Golshid?Baharian Banafsheh?Behzad Sheldon?H.?Jacobson 《Mathematical Methods of Operations Research》2015,81(3):317-336
The sequential stochastic assignment problem (SSAP) allocates N workers to N IID sequentially arriving tasks so as to maximize the expected total reward. This paper studies two extensions of the SSAP. The first one assumes that the values of any two consecutive tasks are dependent on each other while the exact number of tasks to arrive is unknown until after the final arrival. The second extension generalizes the first one by assuming that the number of workers is also random. Optimal assignment policies for both problems are derived and proven to have the same threshold structure as the optimal policy of the SSAP. 相似文献
78.
79.
The effects of boron doping on the structural and electronic properties of (6,0)@(14,0) double-walled silicon carbide nanotube (DWSiCNT) are investigated by using spin-polarized density functional theory. It is found that boron atom could be more easily doped in the inner tube. Our calculations indicate that a Si site is favorable for B under C-rich condition and a C site is favorable under Si-rich condition. Additionally, B-substitution at either single carbon or silicon atom site in DWSiCNT could induce spontaneous magnetization. 相似文献
80.
Prussian blue modified carbon ionic liquid electrodes (PB‐CILEs) were fabricated using chemical and electrochemical procedures. Chemically fabricated PB‐CILE exhibited an excellent sensitivity (0.0866 μA μM?1), low detection limit (0.01 μM) and two linear ranges (0.01–1 and 1–600 μM) toward hydrogen peroxide. Then, glucose oxidase (GOx) was immobilized on the surface of PB‐CILE to fabricate glucose biosensor using three different procedures involving cross linking with glutaraldehyde (GLU) and bovine serum albumin (BSA), entrapment into the Nafion matrix and covering with a sol‐gel layer. Glucose biosensor fabricated using cross linking procedure showed the best sensitivity (0.0019 μA μM?1) and operational stability for glucose. 相似文献