全文获取类型
收费全文 | 3590篇 |
免费 | 1470篇 |
国内免费 | 913篇 |
专业分类
化学 | 646篇 |
晶体学 | 37篇 |
力学 | 827篇 |
综合类 | 119篇 |
数学 | 470篇 |
物理学 | 3874篇 |
出版年
2024年 | 48篇 |
2023年 | 158篇 |
2022年 | 151篇 |
2021年 | 197篇 |
2020年 | 101篇 |
2019年 | 118篇 |
2018年 | 95篇 |
2017年 | 134篇 |
2016年 | 157篇 |
2015年 | 202篇 |
2014年 | 366篇 |
2013年 | 276篇 |
2012年 | 199篇 |
2011年 | 299篇 |
2010年 | 305篇 |
2009年 | 265篇 |
2008年 | 355篇 |
2007年 | 277篇 |
2006年 | 301篇 |
2005年 | 285篇 |
2004年 | 294篇 |
2003年 | 254篇 |
2002年 | 153篇 |
2001年 | 146篇 |
2000年 | 114篇 |
1999年 | 106篇 |
1998年 | 85篇 |
1997年 | 86篇 |
1996年 | 67篇 |
1995年 | 53篇 |
1994年 | 55篇 |
1993年 | 54篇 |
1992年 | 39篇 |
1991年 | 52篇 |
1990年 | 46篇 |
1989年 | 39篇 |
1988年 | 9篇 |
1987年 | 12篇 |
1986年 | 11篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1980年 | 2篇 |
排序方式: 共有5973条查询结果,搜索用时 15 毫秒
111.
Ab initio calculations of accurate dissociation energy and analytic potential energy function for the second excited state B1∏ of 7LiH
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The reasonable dissociation limit of the second excited singlet state
B1∏ of 7LiH molecule is obtained. The accurate dissociation energy and
equilibrium geometry of the B1\Pi state are calculated using a
symmetry-adapted-cluster configuration--interaction method in full active space. The
whole potential energy curve for the B1∏ state is obtained over the
internuclear distance ranging from about 0.10nm to 0.54nm, and has a least-square
fit to the analytic Murrell--Sorbie function form. The vertical excitation energy is
calculated from the ground state to the
B1∏ state and compared with previous theoretical results. The
equilibrium internuclear distance obtained by geometry optimization is found to be
quite different from that obtained by single-point energy scanning under the same
calculation condition. Based on the analytic potential energy function, the harmonic
frequency value of the B1∏ state is estimated. A comparison of the
theoretical calculations of dissociation energies, equilibrium interatomic distances
and the analytic potential energy function with those obtained by previous
theoretical results clearly shows that the present work is more comprehensive and in
better agreement with experiments than previous theories, thus it is an improvement
on previous theories. 相似文献
112.
A unified model of magnetic extraction of spin energy from a black hole in discussed based on the theory of black hole magnetosphere.The magnetic extracting power is expressed by a unified formula,which is applicable to bloth the Blandford-Znajek (BZ) process and the magnetic coupling (MC) process.The strength and characteristics of the BZ power and the MC power are compared in detail.In addition,the impedance matching condition for the BZ power is extended to the more general case. 相似文献
113.
A novel power generator has been achieved to convert vibration to electrical energy via the piezoelectric effect. The generator obtained by micro fabrication process mainly consists of silicon based frame and composite cantilever. The prototype tested at resonant vibration generates 1.15μW of effective power to a 20.4-kΩ resistance load. The potential of this work is to offer miniaturization solutions for power generators, and with the proposed method the ambient ubiquitous vibration can be harvested effectively as endless energy source to form an integrated self-powering system. 相似文献
114.
115.
116.
117.
本文用迭代法对由拉索支承的梁(槽身)的位能进行迭代.通过算例证明,只需取 Fourier 级数前几项就足够,迭代是收敛的.能量法分析斜拉输水结构速度快,方法简单,为该种结构的分析和结构优化提供了近似结构重分析的新方法. 相似文献
118.
刘建强 《理化检验(化学分册)》2002,38(10):525-525,527
美国BAIRD公司生产的DV4光谱仪 ,在CMU 2 0元素板上有 8个通道 ,元素板的总数由仪器中的光电倍增管总数决定 ,最多可分析 32个元素。我公司自 1986年以来 ,先后购进两台美国BAIRD公司生产的DV4光谱仪。该仪器具有自动化程度高、选择性好、操作简单 ,分析速度快 ,可同时进行多元素定量分析 ;校准曲线线性范围宽 ,精度高 ,检出限低。我公司该仪器主要用于转炉、电炉钢包钢样的化学成分 (碳、硅、锰、磷、硫、镍、铬、铜、锡、钼、钒 )分析。在使用过程中出现过一些故障 ,均妥善地进行了处理并解决了存在的问题。以下为典型故… 相似文献
119.
Studies on fluorenscence resonance energy transfer between CdS nanoparticles and DOCAI dyes 总被引:1,自引:0,他引:1
Lun Wang Yan Liu Hong Qi Chen A Ni Liang Fa Gong Xu 《中国化学快报》2007,18(3):369-372
The water-soluble CdS nanoparticles were synthesized in aqueous solution. A novel fluorescence resonance energy transfer (FRET) system with CdS nanoparticles as energy donors and 3,30-diethyl-oxadicarbocyanine iodide (DOCAI) dyes as energy accepter has been developed. 相似文献
120.
JunZhou Yong-zhiQiu Xiao-pengZang Chang-wangPan QiangChen JianShen Si-congLin 《高分子科学》2005,(1):93-102
N,N-dimethyl-N-methacryloyloxyethyl-N-carboxyethyl ammonium (DMMCA) was graft-copolymerized onto the surface of segmented poly(ether urethane) (SPEU) and PE film. The carboxybetaine structure on SPEU and PE film surfaces was confirmed by ATR-FTIR, XPS and water contact angle measurements. Through the experiments with platelet adhesion and protein adhesion assay in vitro, the two materials studied, including poly-DMMCA gel, all show excellent nonthrombogenicity. This confirms once again that the zwitterionic molecular structure on the surfaces of materials is essential for improving their nonthrombogenicity and biocompatibility. 相似文献