全文获取类型
收费全文 | 570篇 |
免费 | 16篇 |
国内免费 | 4篇 |
专业分类
化学 | 338篇 |
晶体学 | 18篇 |
力学 | 34篇 |
数学 | 94篇 |
物理学 | 106篇 |
出版年
2024年 | 2篇 |
2023年 | 5篇 |
2022年 | 18篇 |
2021年 | 20篇 |
2020年 | 21篇 |
2019年 | 14篇 |
2018年 | 10篇 |
2017年 | 13篇 |
2016年 | 20篇 |
2015年 | 15篇 |
2014年 | 21篇 |
2013年 | 57篇 |
2012年 | 18篇 |
2011年 | 30篇 |
2010年 | 28篇 |
2009年 | 16篇 |
2008年 | 33篇 |
2007年 | 23篇 |
2006年 | 26篇 |
2005年 | 19篇 |
2004年 | 28篇 |
2003年 | 18篇 |
2002年 | 21篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 8篇 |
1996年 | 10篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1993年 | 7篇 |
1992年 | 2篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 7篇 |
1978年 | 2篇 |
1976年 | 7篇 |
1975年 | 5篇 |
1974年 | 2篇 |
1966年 | 2篇 |
1964年 | 2篇 |
排序方式: 共有590条查询结果,搜索用时 0 毫秒
581.
Ahmed Jawad Shahzad Azeem Farooq Aamir Kamran Muhammad Ud-Din Khan Salah Ud-Din Khan Shahab 《Journal of Thermal Analysis and Calorimetry》2021,144(6):2175-2185
Journal of Thermal Analysis and Calorimetry - The purpose of this study is to examine the flow features and heat transfer in the presence of nanoparticles which are used to enhance the... 相似文献
582.
The optical properties of CdxZn1−xS thin films on glass substrate prepared by spray pyrolysis method
A series of CdxZn1−xS thin films have been deposited on glass substrates using spray pyrolysis technique. The crystallinity and microstructure of CdxZn1−xS thin films have been investigated by X-ray diffraction (XRD). Based on the results of Hall measurements, the films obtained were an n-type semiconductor. The X-ray data analysis of CdxZn1−xS thin films showed that the grain size of the CdxZn1−xS increased with increase in Cd composition. It is observed that the band gap increases as the Cd composition decreases. The results also showed a blue shift of absorption edge of optical transmission spectra is increases as Zn ratio increases. The effects of Cd composition on the structural and optical properties of CdxZn1−xS thin films were related to their grain size, stress and carrier concentration. 相似文献
583.
584.
Jeong Ryeol Choi Min-Soo Kim Daeyeoul Kim Mustapha Maamache Salah Menouar In Hyun Nahm 《Annals of Physics》2011,326(6):1381-1393
Information theories for the general time-dependent harmonic oscillator are described on the basis of invariant operator method. We obtained entropic uncertainty relation of the system and discussed whether it is always larger than or equal to the physically allowed minimum value. Shannon information and Fisher information are derived by means of density operator that satisfies Liouville–von Neumann equation and their characteristics are investigated. Shannon information is independent of time, but Fisher information is explicitly dependent on time as the time functions of the Hamiltonian vary. We can regard that the Fisher information is a local measure since its time behavior is largely affected by local arrangements of the density, whilst the Shannon information plays the role of a global measure of the spreading of density. To promote the understanding, our theory is applied to special systems, the so-called quantum oscillator with time-dependent frequency and strongly pulsating mass system. 相似文献
585.
586.
The physical aging concept is generally used to explain the typical behavior of amorphous glassy materials such as amorphous polymers. It can be easily evidenced by measuring the effect of a static deformation on the dynamic mechanical properties. In this paper, an attempt is made to determine the “glassy” behavior of elastomeric EPDM chains when they are confined in the vicinity of the filler (glass beads, silicas) surface. It is demonstrated that glassy behavior and physical aging phenomena are detected even with a filled elastomer. Furthermore, the influence of the filler volume fraction, the filler nature and of filler surface treatments with silanes were studied. Finally, an original attempt is made to explain filler-rubber reinforcement by a kind of bimodal network created from linkages between a densely packed interfacial region and the outer loose matrix. 相似文献
587.
Abdellatif M. Salah Eldin 《Heteroatom Chemistry》2003,14(7):612-616
2‐Amino‐1,1,3‐tricyano‐3‐bromopropene was obtained from bromination of 2‐amino‐1,1,3‐tricyanopropene (malononitrile dimer) with N‐bromosuccinimide. This bromo derivative reacts with hydrazine hydrate, phenyl hydrazine, and hydroxylamine hydrochloride to afford pyridazine and oxazine derivatives, respectively. In base‐catalyzed reactions with primary aromatic amines and anthranilic acid derivatives, it produces N‐aryl pyrrol‐3,5‐dicarbonitrile and pyrrolo[1,2‐a]quinazolin‐5‐imine, or pyrrolo[1,2‐a]quinazolin‐5‐one derivatives, respectively. The structures of the newly synthesized heterocycles were established on the basis of elemental analyses and spectral data. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:612–616, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10199 相似文献
588.
Balkis Al‐Saleh Mervat Mohammed Abdel‐Khalik Elham Darwich Ossama Abdel‐Motaleb Salah Mohammed Hilmy Elnagdi 《Heteroatom Chemistry》2002,13(2):141-145
The reactivity of benzotriazolylacetone toward a variety of carbon and nitrogen electrophiles is reported. Several novel azolylbenzotriazoles as well as benzotriazolyl‐cinnolines have been synthesized. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:141–145, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10009 相似文献
589.
The aim of this paper is to study the interactions between packaging and food. For that purpose, additives were first characterized. Kinetic studies of their specific migrations have been carried out by using different analytical methods such as gas chromatography, Fourier transform infrared spectroscopy, atomic absorption spectrometry and differential scanning calorimetric analysis. The influence of various parameters such as temperature, agitation, nature of food simulant and initial concentration of plasticizer was considered. 相似文献
590.
Yu Chen Zhong Shen Lionel Gehringer Holger Frey Salah‐Eddine Stiriba 《Macromolecular rapid communications》2006,27(1):69-75
Summary: Supramolecular interaction of fully methylated hyperbranched polyethylenimines (PEI) with a mesogen‐based carboxylic acid, 5‐(p‐cyanobiphenoxy)pentanoic acid, results in the formation of supramolecular complexes exhibiting thermotropic liquid crystalline (LC) mesophases. In contrast to the common smectic mesophases of most dendritic LC polymers, nematic LC phases were observed. The complexation of PEI and the mesogen units is due to electrostatic interaction between the carboxylate groups and the ammonium end groups of PEI. LC properties were investigated by a combination of differential scanning calorimetry, polarizing light optical microscopy, and X‐ray diffractometry.