全文获取类型
收费全文 | 99篇 |
免费 | 8篇 |
国内免费 | 2篇 |
专业分类
化学 | 9篇 |
力学 | 3篇 |
数学 | 66篇 |
物理学 | 18篇 |
综合类 | 13篇 |
出版年
2022年 | 1篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 1篇 |
2014年 | 4篇 |
2013年 | 18篇 |
2012年 | 5篇 |
2011年 | 5篇 |
2010年 | 2篇 |
2009年 | 6篇 |
2008年 | 3篇 |
2007年 | 3篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 8篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有109条查询结果,搜索用时 437 毫秒
21.
22.
We study a third order singular boundary value problem with multi-point boundary conditions. Sufficient conditions are obtained
for the existence of positive solutions of the problem. Recent results in the literature are significantly extended and improved.
Our analysis is mainly based on a nonlinear alternative of Leray-Schauder. 相似文献
23.
我国青贮玉米的研究现状及市场前景 总被引:17,自引:0,他引:17
青贮玉米作为饲料玉米既能大幅度地提高饲料产量,同时具有较高的营养价值,在国民经济和人民生活中占有越来越重要的地位。在借鉴欧美等发达国家对青贮玉米研究成果的基础上,分析了我国发展青贮玉米的优势和潜力,提出了青贮玉米的育种策略、育种目标和主要用于家畜饲养业的有效利用途径。 相似文献
24.
Significant attention in recent years has been given to obtain a better understanding of human joint ranges, measurement, and functionality, especially in conjunction with commands issued by the central nervous system. While researchers have studied motor commands needed to drive a limb to follow a path trajectory, various computer algorithms have been reported that provide adequate analysis of limb modeling and motion. This paper uses a rigorous mathematical formulation to model human limbs, understand their reach envelope, delineate barriers therein where a trajectory becomes difficult to control, and help visualize these barriers. Workspaces of a typical forearm with 9 degrees of freedom, a typical finger modeled as a 4-degree-of-freedom system, and a lower extremity with 4 degrees of freedom are discussed. The results show that using the proposed formulation, joint limits play an important role in distinguishing the barriers. 相似文献
25.
Saxena A Castán T Planes A Porta M Kishi Y Lograsso TA Viehland D Wuttig M De Graef M 《Physical review letters》2004,92(19):197203
Based on experimental observations of modulated magnetic patterns in a Co0.5Ni0.205Ga0.295 alloy, we propose a model to describe a (purely) magnetic tweed and a magnetoelastic tweed. The former arises above the Curie (or Néel) temperature due to magnetic disorder. The latter results from compositional fluctuations coupling to strain and then to magnetism through the magnetoelastic interaction above the structural transition temperature. We discuss the origin of purely magnetic and magnetoelastic precursor modulations and their experimental thermodynamic signatures. 相似文献
26.
27.
28.
B. Van Der Sijde J.W.H. Dielis W.P.M. Graef 《Journal of Quantitative Spectroscopy & Radiative Transfer》1976,16(12):1011-1015
The natural lifetimes of the (3P)4s2P3/2,1/2 levels of the Ar(II) spectrum have been determined from the natural broadening of argon lines, measured with a Fabry—Pérot interferometer. The natural broadening was determined from the lines with wavelengths of 4880 and 4965 Å by comparing them with the lines at 4806 and 5009 Å having negligible natural broadening. The natural lifetime of the 4s2P3/2 level appeared to be τ = 0.19 (±6%) ns and of the 4s2P1/2 level τ = 0.18 (±15%) ns. These values are about 1.5 to 2 times as small as those determined by other authors either experimentally by using a Fabry—Pérot interferometer by the method of Ballik, or calculated using intermediate coupling.The differences between the two experimental methods are discussed. 相似文献
29.
Sufficient conditions for continuability, boundedness, and convergence to zero of solutions of (a(t)x′)′ + h(t, x, x′) + q(t) f(x) g(x′) = e(t, x, x′) are given. 相似文献
30.
M. Meincken S. Graef K. Mueller-Nedebock R.D. Sanderson 《Applied Physics A: Materials Science & Processing》2002,74(3):371-375
A new method has been developed to measure thermal transitions by atomic force microscopy in the non-contact mode, using it
as a dynamic mechanical analyser on a local scale. In this method the cantilever is oscillating above the polymer surface
and the resonance frequency is measured as a function of the temperature. Thermal transitions of a polymer are clearly visible
as a change in the characteristic-frequency behaviour of the cantilever. This paper introduces a simple model to explain the
response of the cantilever caused by the transitions in the polymer and the related form of the frequency/temperature curves.
This new technique adds a new dimension to the standard thermal analysis techniques, with which the thermal transitions of
different polymer phases can be resolved individually for polymer blends or copolymers, for example in structured multiphase
polymers.
Received: 1 November 2001 / Accepted: 7 November 2001 / Published online: 23 January 2002 相似文献