全文获取类型
收费全文 | 82901篇 |
免费 | 6618篇 |
国内免费 | 5435篇 |
专业分类
化学 | 24005篇 |
晶体学 | 1808篇 |
力学 | 3540篇 |
综合类 | 368篇 |
数学 | 21944篇 |
物理学 | 43289篇 |
出版年
2023年 | 239篇 |
2022年 | 198篇 |
2021年 | 377篇 |
2020年 | 687篇 |
2019年 | 1031篇 |
2018年 | 1000篇 |
2017年 | 694篇 |
2016年 | 544篇 |
2015年 | 480篇 |
2014年 | 1212篇 |
2013年 | 1903篇 |
2012年 | 1238篇 |
2011年 | 1852篇 |
2010年 | 2449篇 |
2009年 | 7042篇 |
2008年 | 8110篇 |
2007年 | 6597篇 |
2006年 | 6021篇 |
2005年 | 4143篇 |
2004年 | 3930篇 |
2003年 | 4122篇 |
2002年 | 5343篇 |
2001年 | 3834篇 |
2000年 | 3606篇 |
1999年 | 3434篇 |
1998年 | 2832篇 |
1997年 | 1991篇 |
1996年 | 1789篇 |
1995年 | 2222篇 |
1994年 | 2160篇 |
1993年 | 1602篇 |
1992年 | 1115篇 |
1991年 | 838篇 |
1990年 | 683篇 |
1989年 | 605篇 |
1988年 | 572篇 |
1987年 | 406篇 |
1985年 | 956篇 |
1984年 | 625篇 |
1983年 | 495篇 |
1982年 | 653篇 |
1981年 | 801篇 |
1980年 | 737篇 |
1979年 | 569篇 |
1978年 | 594篇 |
1977年 | 546篇 |
1976年 | 545篇 |
1975年 | 320篇 |
1974年 | 357篇 |
1973年 | 464篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
221.
XiWenHE HongShengGUO YuMeiJIA 《中国化学快报》2003,14(9):979-982
In order to obtain mechanically stable membrane for practical application, the imprinted polymer was synthesized in the pores of polyfluoromembrane, the binding and transport ability of the membrane were studied. 相似文献
222.
S. Mancini D. Vitali V. Giovannetti P. Tombesi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):417-422
We show that the optomechanical coupling between an optical cavity mode and two movable cavity mirrors is able to entangle
two different macroscopic oscillation modes of the mirrors. This continuous variable entanglement is maintained by the light
bouncing between the mirrors and is robust against thermal noise. In fact, it could be experimentally demonstrated using present
technology.
Received 2 September 2002 / Received in final form 10 October 2002 Published online 7 January 2003 相似文献
223.
Chemisorption at interfaces between organic semiconductors and metals: role of the electron affinity
Chemisorption is a well-known phenomenon for many interfaces between organic semiconductors and metals. It is shown that many published data indicate that the occurrence of chemisorption can be rationalized upon the consideration of the metal work function versus the electron affinity of the organic semiconductor. 相似文献
224.
A method for fabricating well-dispersed nanowire suspension has been demonstrated in the paper. Thin gold nanowires were prepared by template synthesis, and then functionalized with sulphonate group-terminated thiols before suspended in different solvents. The degree of aggregation of the obtained suspension was evaluated with transmission electron microscopy (TEM) and UV-vis spectroscopy. It was found that the degree of aggregation was predominated by the solvents, and the best degree of dispersion was obtained when isopropyl alcohol (IPA) was used as the solvent. The gold nanowires from the suspension can be selectively assembled onto chemically patterned substrates. This well-dispersed nanowire suspension is potentially useful for fabricating novel nanodevices. 相似文献
225.
Xiao Qi ZHENG Yong Hui WANG Qing Xiang GUO* Li YANG You Cheng LIU Department of Chemistry University of Science Technology of China Hefei National Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou 《中国化学快报》2003,(8)
As artificial enzymes, the binding constants of cyclodextrins (CDs) and their substrates are expected to be high1. For this purpose, many kinds of bridged cyclodextrin dimers2 whose two cyclodextrins are linked by various spacers have been constructed. It was of interest to make the dimers, whose binding constants would exceed 108dm3/mol3. Up to date, the bridged cyclodextrin dimers have been extensively studied as enzyme models and as molecular receptors4-6. Recently, we synthesized a brid… 相似文献
226.
研究非Chetaev型变质量非完整系统的Lie对称性与Noether对称性以及其间的 关系,给出Lie对称性导致Noether对称性以及Noether对称性导致Lie对称性的条件. 相似文献
227.
B.V. Raghavaiah 《Journal of Physics and Chemistry of Solids》2004,65(6):1153-1164
PbO-Sb2O3 glasses added with different concentrations of As2O3 (10-55 mol%) were prepared to understand their IR spectra, elastic properties (Young's modulus E, Shear modulus G, microhardness H), optical absorption and dielectric properties (constant ε, loss tan δ, ac conductivity σac over a moderately wide range of frequency and temperature and breakdown strength in air medium at room temperature). Results have indicated that the structure of the PbO-Sb2O3-As2O3 glass is more rigid when the concentration of As2O3 is around 40 mol%. 相似文献
228.
The photocatalytic degradation of a herbicide derivative, 2,4-dichlorophenoxy acetic acid (2,4-D, 1), has been investigated in aqueous suspensions of titanium dioxide. The degradation was studied by monitoring the change in substrate concentration employing UV spectroscopic analysis and decrease in Total Organic Carbon (TOC) content as a function of irradiation time in the presence of UV light source. The degradation kinetics was investigated under a variety of conditions, such as different types of TiO2, pH, catalyst and substrate concentrations. Higher photonic efficiencies were observed with Degussa P25 as compared with other photocatalysts. The degradation products were analysed by GC-MS and probable pathways for the formation of different products were proposed. 相似文献
229.
在1.2×1013W·cm-2低功率密度下,对基频激光预主短脉冲驱动类镍银X光激光机理进行了数值模拟和理论分析。证实了在靶长23 mm范围内X光激光都能获得有效放大,取得了和实验相符合的结果。考虑了单柱面镜线聚焦沿靶长度方向功率密度的非均匀性对X光激光放大的影响,采用弯曲靶能有效克服折射以及单柱面镜线聚焦功率密度非均匀带来的不利影响。理论模拟给出的类镍银X光激光的出光下限泵浦功率密度也与实验符合得很好。理论模拟还表明,采用1%左右的预脉冲强度并对预主脉冲时间间隔进行优化,X光激光的输出能量和能量转换效率将获得大幅度提高。 相似文献
230.
Cr3+:MgAl2O4晶体EPR参量及其电子精细光谱的研究 总被引:4,自引:0,他引:4
考虑了SS(Spin-Spin)作用和SOO(Spin-Other-Orbit)作用,采用完全对角化方法,结合自旋Hamiltonian理论,研究了Cr3+∶MgAl2O4晶体EPR参量及其吸收光谱,理论与实验符合甚好. 在此基础上,进一步研究了4A2(3d3)离子EPR参量的微观起源. 研究表明,EPR参量起源于四种微观机制:(1) SO(Spin-Orbit) 耦合机制;(2) SS耦合机制;(3)SOO耦合机制;(4) SO~SS~SOO总联合作用机制. 在这些机制中,SO机制是最主要的. 相似文献