全文获取类型
收费全文 | 414篇 |
免费 | 19篇 |
国内免费 | 3篇 |
专业分类
化学 | 257篇 |
力学 | 16篇 |
数学 | 41篇 |
物理学 | 122篇 |
出版年
2023年 | 4篇 |
2022年 | 6篇 |
2021年 | 5篇 |
2020年 | 9篇 |
2019年 | 14篇 |
2018年 | 22篇 |
2017年 | 14篇 |
2016年 | 33篇 |
2015年 | 15篇 |
2014年 | 32篇 |
2013年 | 49篇 |
2012年 | 38篇 |
2011年 | 51篇 |
2010年 | 23篇 |
2009年 | 30篇 |
2008年 | 26篇 |
2007年 | 18篇 |
2006年 | 14篇 |
2005年 | 8篇 |
2004年 | 6篇 |
2003年 | 1篇 |
2002年 | 3篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1990年 | 4篇 |
1989年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
排序方式: 共有436条查询结果,搜索用时 15 毫秒
101.
102.
Elahe Moazzen Homeira Ebrahimzadeh Mostafa M. Amini Omid Sadeghi 《Journal of separation science》2013,36(11):1826-1833
In this work, for the first time, an ion‐imprinted polymer was developed for selective extraction and determination of gold ions. To increase the sorbent efficiency, this polymer was coated on a novel nanoporous carbon‐based material, carbohydrate‐derived Max‐Planck Gesellschaft 1, which is also the first example of grafting imprinted polymer on nanoporous‐carbon material. These particles were applied successfully for preconcentration of ultratrace amount of gold ions, following determination by flame atomic absorption spectrometry. Some effective factors on the efficiency of gold ions extraction, such as concentration and volume of eluent, sample and eluent flow rates, and also effect of interfering ions especially palladium and platinum ions, were investigated. The LOD was determined to be 0.27 ng/mL. Furthermore, the precision of the method was calculated to be 2.14% under optimal conditions with recovery more than 97.3%. The technique was also used to determine the concentration of gold ions in mine stone samples with satisfactory results. The accuracy of this method was investigated by determination of gold ions concentrations in several reference materials with certified gold content. 相似文献
103.
Zahra Khoubi-Arani Seyed Reza Ghaffarian Gity Mir Mohamad Sadeghi 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(2):180-188
Flexible elastomeric polyurethane (EPU) films were synthesized by ultraviolet (UV) curing of thermoplastic polyurethanes (TPUs) through the reaction among poly (oxytetramethylene) diol (PTMO), isophorone diisocyanate (IPDI), cis-2-butene-1,4-diol (cis-BDO), and 1,6-hexanediol diacrylate (HDDA). In order to improve elasticity and structural permanency in the synthesized TPUs, cross-linking reaction involving unsaturated groups of chain extender (cis-BDO) and reactive diluent (HDDA) using 27 and 41 seconds of UV radiation is introduced. Investigation of structure and mechanical properties was performed using FTIR, GPC, and tensile tests. Stress-strain behavior showed that Young's moduli of EPUs were in the range of 0.2 to 0.4 MPa, which is evidence for high flexibility. Three times of repeated loading on one sample up to 100% strain with 10 min intervals for its recovery showed that considerable structural change didn't occur under these conditions and all observed permanent sets vanished within a time not exceeding 10 min. 相似文献
104.
H. Rahbar M. R. Pahlavani J. Sadeghi H. Moayyeri 《International Journal of Theoretical Physics》2009,48(7):2072-2080
In this paper we discuss the one-dimensional non-linear harmonic oscillator and isotropic oscillator in positive curvature.
We will see that in the special case two different oscillator have a same behavior. Finally, by using the parasupersymmetry
algebra we obtain the partner potential and superpotential. These superpotential lead us to obtain the corresponding superchares. 相似文献
105.
Assrary M. Sadeghi J. Zomorrodian M. E. 《International Journal of Theoretical Physics》2021,60(9):3254-3270
International Journal of Theoretical Physics - It has been shown that AdS/CFT correspondence may be realized between some AdS-like cosmological space and CFT living on the boundary. By extending... 相似文献
106.
Bahram Sadeghi Bigham Marzieh Eskandari Maryam Tahmasbi 《Journal of computational science》2012,3(3):127-131
The polar diagram of a set of points in a plane and its extracted dual EDPD were recently introduced for static and dynamic cases. In this paper, the near-pole polar diagram NPPD for a set of points is presented. This new diagram can be considered as a generalization of the polar diagram and has applications in several communication systems and robotics problems. After reviewing the NPPD of points, we solve the problem for a set of line segments and simple polygons in optimal time Θ(n log n), where n is the number of line segments or polygon vertices. We introduce duality for the NPPD of points and identify some applications. 相似文献
107.
DC electrorheological response of polyethylene/organically modified layered silicate nanocomposites 下载免费PDF全文
Soheil Sadeghi Mohammad Arjmand Tieqi Li Uttandaraman Sundararaj 《Journal of Polymer Science.Polymer Physics》2017,55(17):1298-1309
The present work reports the electrorheological (ER) response of high‐density polyethylene (HDPE)/organically modified silicate layers nanocomposites based on four commercially available HDPE matrices. Two single‐site catalyzed bimodal resins, one single‐site catalyzed unimodal resin and one Ziegler–Natta catalyzed unimodal resin are studied. It is revealed that the distinct separation of the two modes of the bimodal HDPE resins significantly enhances the ER response. It is proposed that the slower structural relaxation modes introduced by higher molecular weight species in the bimodal HDPE matrices enhance the ER response of the nanocomposites. This is ascribed to the longer induction time for leaking current density, which is an indicator of mobility and release of immobilized cationic surfactants at the silicate layers surface induced by field exposure. It is found that the screening effect of prematurely released cationic surfactants leads to a weaker ER response in nanocomposites whose matrices have faster relaxation modes. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1298–1309 相似文献
108.
Research on Chemical Intermediates - A novel six-coordinate complex of Zr(IV) with curcumin ligand was synthesized and characterized by thermogravimetric analysis, elemental analysis and... 相似文献
109.
110.
Bayat Zeinab Saeedzadeh Elham Vahidfar Nasim Sadeghi Mahdi Farzenefar Saeed Daha Fariba Johari Salehi Yalda 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(2):691-700
Journal of Radioanalytical and Nuclear Chemistry - Radiocolloides are essential for the detection of metastatic lymph nodes in breast cancer. In this study [67Ga]Ga-phytate, as an long-lived... 相似文献