全文获取类型
收费全文 | 2035篇 |
免费 | 425篇 |
国内免费 | 312篇 |
专业分类
化学 | 1580篇 |
晶体学 | 36篇 |
力学 | 124篇 |
综合类 | 23篇 |
数学 | 232篇 |
物理学 | 777篇 |
出版年
2024年 | 6篇 |
2023年 | 46篇 |
2022年 | 76篇 |
2021年 | 90篇 |
2020年 | 118篇 |
2019年 | 102篇 |
2018年 | 110篇 |
2017年 | 103篇 |
2016年 | 128篇 |
2015年 | 136篇 |
2014年 | 162篇 |
2013年 | 201篇 |
2012年 | 227篇 |
2011年 | 207篇 |
2010年 | 141篇 |
2009年 | 114篇 |
2008年 | 110篇 |
2007年 | 90篇 |
2006年 | 64篇 |
2005年 | 66篇 |
2004年 | 58篇 |
2003年 | 42篇 |
2002年 | 50篇 |
2001年 | 45篇 |
2000年 | 47篇 |
1999年 | 45篇 |
1998年 | 22篇 |
1997年 | 24篇 |
1996年 | 23篇 |
1995年 | 15篇 |
1994年 | 9篇 |
1993年 | 13篇 |
1992年 | 16篇 |
1991年 | 13篇 |
1990年 | 3篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 7篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1977年 | 3篇 |
1975年 | 1篇 |
1957年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有2772条查询结果,搜索用时 31 毫秒
151.
152.
A novel long-lasting afterglow phosphor ZrO2:Ti is prepared by the conventional solid-stated method and their luminescent properties are investigated. A bluish white strong and broad emissive band, which is attributed to originate from the recombination of electrons trapped by F+ centers and the holes created in Valence band, is observed under 254 nm UV irradiation. The identical color long afterglow, which lasts about 1 h, is found in the ZrO2:Ti phosphor after removing the 254 nm UV light. The mechanism of the long lasting phosphorescence (LLP) has been discussed based on the thermoluminescence (TL) results. The replacement of Zr by Ti produces more anion vacancies, resulting in the enhanced photoluminescence (PL) and LLP of ZrO2:Ti sample. These results indicate that ZrO2:Ti phosphor has potential promising applications. 相似文献
153.
We design a new three-dimensional double-wing fractional-order chaotic system with three quadratic terms, confirmed by numerical simulation and circuit implementation. We then study the synchronization between the new double-wing fractional-order chaotic system and different Lorenz systems with different structures. In the process of the synchronization, the definition of ‘the simplest response system’ and the practical method of designing the circuit have been originally proposed. The circuit of ‘the simplest response system’ (even the simplest incommensurate-order response system), holding different structures with the drive system, of any one integral or fractional drive system now can be designed effectively and sufficiently. Our results are supported by numerical simulation and circuit implementation. 相似文献
154.
Jian Wu WANG* Jiong JIA Hong Mei LI Cong WANG School of Chemistry Environmental Science Shandong University Jinan 《中国化学快报》2000,11(11)
Losartan 1 (Dup-753) is a nonpeptide angiotensin II receptor (type AT1) antagonist discovered by Duncia, J.V. et al. 1 in 1990 and its potassium salt (cozaar) has been marketed as an antihypertensive since 1995 2. 1 2 Starting from Dup-753, a great number of structural related compounds have been prepared by several laboratories and several antihypertensive drugs have been developed3. In order to find new and more active compounds, a novel type of Losartan analogues 2 was designed and syn… 相似文献
155.
The expansion coefficient CD|L| of Coulomb potential 1/r12 of atomic system in hyper‐spherical harmonics is derived and the explicit expression is given. 相似文献
156.
本文将报告对硅纳米线、多孔硅、Si C纳米棒和碳纳米管等一维纳米体系的本征拉曼光谱及其特征的研究结果 ,并讨论拉曼光谱在上述材料的几何和物理特性研究中的应用。 相似文献
157.
The light-oxygen effect consists in a direct excitation of molecular oxygen dissolved in aqueous media of biosystems by the
light; it provides the possibility to use lasers for therapeutic purposes. The wavelength of the used light should strictly
correspond to the oxygen absorption bands. However, laser therapy also makes use of lasers emitting at 0.89 μm (outside the known oxygen bands), which suggests the action of a new photoreceptor. Here we argue that this mechanism of
photoreception is a modification of the light-oxygen effect involving the absorption of photon simultaneously by the oxygen
molecule and O-H stretch of the H20 molecule of liquid water. 相似文献
158.
Synthetic metalloporphyrin are efficient models of the cytochrome P-450 family ofmono-oxygen enzymes and have been largely used as catalysts in oxidation of alkanesand epoxidation of alkenesl. Polymer-bonded metalloporphyrin reveal many advantageson the catalytic reaction, where the catalysts can be easily separated from the products,recovered, and reused2. Quaternary ammonium salts as phase transfer catalysts werewide used in aqueous-organic two-phase conditions. Unfortunately, most porphyrin… 相似文献
159.
160.