全文获取类型
收费全文 | 3092篇 |
免费 | 259篇 |
国内免费 | 294篇 |
专业分类
化学 | 513篇 |
晶体学 | 7篇 |
力学 | 477篇 |
综合类 | 57篇 |
数学 | 1783篇 |
物理学 | 808篇 |
出版年
2023年 | 24篇 |
2022年 | 46篇 |
2021年 | 52篇 |
2020年 | 48篇 |
2019年 | 61篇 |
2018年 | 65篇 |
2017年 | 94篇 |
2016年 | 79篇 |
2015年 | 56篇 |
2014年 | 117篇 |
2013年 | 210篇 |
2012年 | 111篇 |
2011年 | 147篇 |
2010年 | 143篇 |
2009年 | 127篇 |
2008年 | 194篇 |
2007年 | 209篇 |
2006年 | 173篇 |
2005年 | 173篇 |
2004年 | 154篇 |
2003年 | 134篇 |
2002年 | 154篇 |
2001年 | 142篇 |
2000年 | 135篇 |
1999年 | 109篇 |
1998年 | 119篇 |
1997年 | 99篇 |
1996年 | 81篇 |
1995年 | 41篇 |
1994年 | 43篇 |
1993年 | 24篇 |
1992年 | 35篇 |
1991年 | 27篇 |
1990年 | 19篇 |
1989年 | 24篇 |
1988年 | 11篇 |
1987年 | 11篇 |
1986年 | 22篇 |
1985年 | 15篇 |
1984年 | 14篇 |
1983年 | 8篇 |
1982年 | 20篇 |
1981年 | 10篇 |
1980年 | 10篇 |
1979年 | 14篇 |
1978年 | 14篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1973年 | 3篇 |
1936年 | 3篇 |
排序方式: 共有3645条查询结果,搜索用时 0 毫秒
11.
A complete normal coordinate analysis was performed for five-coordinate non-rigid triarylantimony diester SbPh3(O2CR)2, known to be a bioactive molecule, using Wilson G-F matrix method and Urey Bradley force field. The study of vibrational
dynamics was performed using the concept of group frequencies and band intensities.
相似文献
12.
A general model of the equations of the Lord-Şulman theory including one relaxation time and the Green-Lindsay theory with two relaxation times, as well as the classical dynamical coupled theory, are applied to the study of the influence of reinforcement on the total deformation for an infinite space weakened by a finite linear opening mode-I crack. We study the influence of reinforcement on the total deformation of rotating thermoelastic half-space and their interaction with each other. The material is homogeneous isotropic elastic half space. The crack is subjected to prescribed temperature and stress distributions. The normal mode analysis is used to obtain the exact expressions for displacement components, force stresses, and temperature. The variations of the considered variables with the horizontal distance are illustrated graphically. Comparisons are made with the results obtained in the three theories with and without rotation. A comparison is also made between the two theories for different depths. 相似文献
13.
14.
本文推导出包括正常和反常声光互作用在内的多频声光耦合波方程的普适形式,并得出两个独立超声波信号时布拉格状态下方程的解.分析了多频声光互作用的各种线性和非线性效应,包括衍射效率、压缩、交叉调制和各级互调制强度等,并指出反常与正常多频声光衍射的差异.结论是反常多频声光互作用情况下,各级互调制模强度与主衍射模强度的比值小于正常多频声光互作用情况下的相应比值.实验结果与理论分析相符. 相似文献
15.
Hawking radiation of Weyl neutrinos in a rectilinearly non—uniformly accelerating Kinnersley black hole 下载免费PDF全文
The quantum thermal effect of Weyl neutrinos in a rectilinearly non-uniformly accelerating Kinnersley black hole is investigated using the generalized tortoise coordinate transformation.The equations that determine the location,the Hawking temperature of the event horizon and the thermal radiation spectrum of neutrinos are derived.Our results show that the location and the temperature of the event horizon depend not only on the time but also on the angle. 相似文献
16.
机载光电平台目标定位与误差分析 总被引:3,自引:0,他引:3
根据机载光电平台的特点,建立了6个坐标系统,进行了8次线性变换,构建了从光电平台成像系统像面坐标系到大地地理坐标系的目标定位数学模型。计算了目标在大地地理坐标系的经纬度和高程坐标,分析了各种测量参数对目标定位精度的影响。通过建立误差模型和仿真数据进行目标定位实验,采用蒙特卡罗方法统计目标定位误差。实验结果表明,载机经纬度误差、载机姿态角度误差及光电平台指向角度误差是影响目标定位精度的主要因素,其中载机经纬度误差直接传递到目标定位误差,载机姿态角度误差和光电平台指向角度误差大体上以10-4~10-2比例作用到目标定位误差。本文方法有效可行,对机载光电平台目标定位具有实用价值。 相似文献
17.
18.
19.
A theorem proved by R. Høegh-Krohn in Comm. Math. Phys. 38(1974), 195–224, which yields a possibility to define states of systems of quantum particles by their values on the products
, where \mathfraka
t
, t
are time automorphisms and F
j
are multiplication operators, is generalized and extended. In particular, it is shown that the algebras generated by such products with F
j
taken from the families of multiplication operators satisfying certain conditions are dense in the algebras of observables in the -weak topology, in which normal states are continuous. This result was obtained for the systems with two types of kinetic energy: the usual one expressed by means of the Laplacian; the relativistic kinetic energy defined by a pseudo-differential operator. 相似文献
20.
The IR spectrum of 4-O-methyl-2,3,6-tri-O-nitromethyl-β-D-glucopyranoside has been interpreted in detail for the first time
based on complete calculation of the normal vibration frequencies and absolute intensities of its IR absorption bands and
a comparison of them with the corresponding experimental data. The results indicate that the location of the nitrates in cellulose
nitrates can be determined experimentally from separate components of complicated absorption bands in the ranges 1700–1600
and 900–800 cm−1 of the IR spectrum.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 1, pp. 43–51, January–February, 2008. 相似文献