全文获取类型
收费全文 | 2021篇 |
免费 | 241篇 |
国内免费 | 214篇 |
专业分类
化学 | 1201篇 |
晶体学 | 33篇 |
力学 | 90篇 |
综合类 | 45篇 |
数学 | 206篇 |
物理学 | 901篇 |
出版年
2024年 | 5篇 |
2023年 | 33篇 |
2022年 | 49篇 |
2021年 | 54篇 |
2020年 | 58篇 |
2019年 | 80篇 |
2018年 | 70篇 |
2017年 | 46篇 |
2016年 | 77篇 |
2015年 | 65篇 |
2014年 | 77篇 |
2013年 | 107篇 |
2012年 | 150篇 |
2011年 | 147篇 |
2010年 | 101篇 |
2009年 | 115篇 |
2008年 | 110篇 |
2007年 | 96篇 |
2006年 | 95篇 |
2005年 | 109篇 |
2004年 | 93篇 |
2003年 | 77篇 |
2002年 | 68篇 |
2001年 | 102篇 |
2000年 | 50篇 |
1999年 | 63篇 |
1998年 | 55篇 |
1997年 | 44篇 |
1996年 | 37篇 |
1995年 | 38篇 |
1994年 | 26篇 |
1993年 | 23篇 |
1992年 | 16篇 |
1991年 | 16篇 |
1990年 | 33篇 |
1989年 | 17篇 |
1988年 | 10篇 |
1987年 | 11篇 |
1986年 | 19篇 |
1985年 | 8篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1981年 | 2篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 3篇 |
1973年 | 1篇 |
排序方式: 共有2476条查询结果,搜索用时 421 毫秒
961.
Experimental Study of the Thermal Decomposition Properties of Binary Imidazole Ionic Liquid Mixtures
Fan Yang Xin Zhang Yong Pan Hongpeng He Yuqing Ni Gan Wang Juncheng Jiang 《Molecules (Basel, Switzerland)》2022,27(4)
Ionic liquids (ILs) have a wide range of applications, owing to their negligible vapor pressure, high electrical conductivity, and low melting point. However, the thermal hazards of ILs and their mixtures are also non-negligible. In this study, the thermal hazards of various binary imidazolium ionic liquids (BIIL) mixtures were investigated. The effects of parent salt components and molar ratios on the thermal decomposition temperature (Td) and flashpoint temperature (Tf) are investigated. It is found that both Td and Tf increase as the proportion of highly thermally stable components in BIIL mixtures increases. Furthermore, the decomposition process of BIIL mixtures can be divided into two stages. For most molar ratios, the Tf of the BIIL mixtures is in the first stage of thermal decomposition. When the proportion of highly thermally stable components is relatively high, Tf is in the second stage of thermal decomposition. The flammability is attributed to the produced combustible gases during the thermal decomposition process. This work would be reasonably expected to provide some guidance for the safety design and application of IL mixtures for engineering. 相似文献
962.
963.
964.
965.
Anion-exchange resin (AER) and choline chloride-based deep eutectic solvent-modified anion-exchange resin (DES-AER) were prepared, and their performance properties were assessed by Fourier transform infrared spectrometer (FTIR), field emission scanning electron microscopy (FE-SEM), and adsorption experiments. In addition, the separation characteristics on the solid-phase extraction (SPE) cartridges packed with octadecyl silica (ODS), AER, and DES-AER for rapid extraction of cleistanthol from Phyllanthus flexuosus extracts have been evaluated, with recoveries of the materials tested at 72.14, 68.21, and 82.11%, respectively. All results demonstrated that DES-AER not only offered higher adsorption capacity for cleistanthol but also exhibited better extraction efficiency of cleistanthol than those of ODS and AER. In this work, it is the first application of DES in the modification of AER, and the proposed DES-AER showed significant affinity and selectivity toward cleistanthol, which could have potential application for natural product extraction. 相似文献
966.
Release of the Water Molecule Encapsulated Inside an Open‐Cage Fullerene through Hydrogen Bonding Mediated by Hydrogen Fluoride 下载免费PDF全文
Liang Xu Hongjiang Ren Sisi Liang Jiahao Sun Prof. Dr. Yajun Liu Prof. Dr. Liangbing Gan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(39):13539-13543
A reversible wetting/dewetting procedure is reported for an open‐cage fullerene with an 18‐membered orifice. In a homogeneous mixture of H2O/EtOH/CHCl3, water was encapsulated into the cavity of the open‐cage compound quantitatively at 80 °C. Addition of aqueous hydrogen fluoride into the water‐encapsulated complex removed the encapsulated water completely at room temperature. H‐bonding between the trapped water and fluoride is shown to play a key role for the water release process. 相似文献
967.
AgInSbTe薄膜的短波长记录性能分析 总被引:1,自引:0,他引:1
采用自制的装置研究了Ag5In5Sb47Te33薄膜的静态记录性能与记录激光的功率和脉冲宽度的关系,并对其记录畴形貌特点进行了直接观察。结果表明只有记录激光的功率和脉冲宽度在一定范围之内才能起到信息记录的作用,所得的记录畴形貌十分清晰,基本为非晶态Ag5In5Sb47Te33;小于该范围的激光能量不能使材料结构发生较大的变化,所得的记录畴形貌模糊,反射率对比度低于2%;大于该范围所得的记录畴由烧蚀区和其周围的非晶态Ag5In5Sb47Te33组成。另外,得到了记录激光功率为12mW、脉冲宽度为90ns的Ag5In5Sb47Te33薄膜的短波长最佳记录条件,其记录畴的反射率对比度为22%,直径为380nm-400nm。 相似文献
968.
Z. Liu Y.H. Zhang X.H. Zhou M.L. Liu W.J. Luo Q.Y. Pan Z.G. Gan T. Hayakawa M. Oshima Y. Toh T. Shizima Y. Hatsukawa A. Osa T. Ishii M. Sugawara 《The European Physical Journal A - Hadrons and Nuclei》2002,13(3):277-280
Excited states of 142Ce, populated in deep inelastic reactions of 82Se projectiles bombarding 139La target, have been studied up to medium spins using in-beam γ spectroscopy techniques. Three new levels have been identified
at 2625, 2995, 3834 keV, and assigned as 8+, 9(-) and 11(-), respectively. These new yrast states follow closely the level systematics of the even mass N = 84 isotones. Their strctures have been discussed with the help of empirical shell model calculations.
Received: 2 November 2001 / Accepted: 15 January 2002 相似文献
969.
970.
本文从瞬态闪光的应用引入瞬态辐射的光性测量,重点介绍瞬态辐射光度、瞬态辐射谱及瞬态辐射光度的测量原理、方法和手段以及有关测量结果处理遵从的法则等。 相似文献