全文获取类型
收费全文 | 2087篇 |
免费 | 136篇 |
国内免费 | 296篇 |
专业分类
化学 | 1549篇 |
晶体学 | 13篇 |
力学 | 443篇 |
综合类 | 15篇 |
数学 | 175篇 |
物理学 | 324篇 |
出版年
2024年 | 8篇 |
2023年 | 23篇 |
2022年 | 44篇 |
2021年 | 79篇 |
2020年 | 79篇 |
2019年 | 73篇 |
2018年 | 74篇 |
2017年 | 71篇 |
2016年 | 109篇 |
2015年 | 69篇 |
2014年 | 93篇 |
2013年 | 189篇 |
2012年 | 87篇 |
2011年 | 104篇 |
2010年 | 69篇 |
2009年 | 87篇 |
2008年 | 116篇 |
2007年 | 100篇 |
2006年 | 98篇 |
2005年 | 115篇 |
2004年 | 113篇 |
2003年 | 88篇 |
2002年 | 80篇 |
2001年 | 72篇 |
2000年 | 70篇 |
1999年 | 57篇 |
1998年 | 39篇 |
1997年 | 49篇 |
1996年 | 63篇 |
1995年 | 49篇 |
1994年 | 32篇 |
1993年 | 33篇 |
1992年 | 18篇 |
1991年 | 24篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有2519条查询结果,搜索用时 31 毫秒
181.
N. S. Romanovskii 《Algebra and Logic》2008,47(6):426-434
A soluble group G is rigid if it contains a normal series of the form G = G1 > G2 > … > Gp > Gp+1 = 1, whose quotients Gi/Gi+1 are Abelian and are torsion-free as right ℤ[G/Gi]-modules. The concept of a rigid group appeared in studying algebraic geometry over groups that are close to free soluble.
In the class of all rigid groups, we distinguish divisible groups the elements of whose quotients Gi/Gi+1 are divisible by any elements of respective groups rings Z[G/Gi]. It is reasonable to suppose that algebraic geometry over divisible rigid groups is rather well structured. Abstract properties
of such groups are investigated. It is proved that in every divisible rigid group H that contains G as a subgroup, there is
a minimal divisible subgroup including G, which we call a divisible closure of G in H. Among divisible closures of G are divisible
completions of G that are distinguished by some natural condition. It is shown that a divisible completion is defined uniquely
up to G-isomorphism.
Supported by the Council for Grants (under RF President) and State Aid of Leading Scientific Schools (grant NSh-344.2008.1).
Translated from Algebra i Logika, Vol. 47, No. 6, pp. 762–776, November–December, 2008. 相似文献
182.
朱文余和孙琦(见《数学进展》,2004,33(4):505-507)提出了关于3阶Carmichael数的三个问题,我们(见《四川大学学报(自然科学版)》,2006,43(6):1197-1201)肯定地回答了问题1.本文模仿Howe的寻找严格2阶Carmichael数(见Mathematics of Computation,2000,69(232):1711—1719)的方法,提出寻找满足某种条件的3阶Carmichael数的方法,并用这种方法确实找到了几百个这样的数,因而完全肯定地回答了问题2. 相似文献
183.
刘鹏林 《数学的实践与认识》2005,35(5):80-84
通过运用波前干涉理论,得到了贴片云纹干涉法测圆柱壳的位移与应变公式,分析了刚体位移及曲率对测试结果的影响情况.指出了在对压力容器及管道进行测试时应注意的事项. 相似文献
184.
185.
186.
E. Rudnik I. Resiak C. Wojciechowski Z. Dobkowski 《Journal of Thermal Analysis and Calorimetry》2001,64(2):495-500
Laboratory-made asymmetric polyurethane membranes designed for immunoisolation were investigated. Two types of EK and ES membranes
were prepared in different spinning conditions.
The membrane structure was characterised by the skin pore radius measurements using differential scanning calorimetry (DSC).
Diffusive transport properties of membranes were determined by in vitro method for albumin and creatinine. The scanning electron
microscopy (SEM) was applied to study the morphology of membranes.
It has been found that the DSC technique is a useful tool for the evaluation of pore radii in the skin layer for PU membranes.
Calculated pore radii were in the range from 1.95 to 2.47 nm for the EK and ES types. A correlation between the skin pore
radii and the transport properties was not found in this case of investigated membranes. However, the transport properties
data can serve for the estimation of selectivity of membranes. Thus, the selectivity of membranes for solutes of various molecular
size was estimated from the D
m/D
w ratio of diffusion coefficients for albumin and creatinine. The SEM micrographs reveal the finger-like internal structure
of capillary membranes, as well as various skin thickness.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
187.
188.
Bing Yong HSIE Zhi Bin LIANG 《数学学报(英文版)》2007,23(9):1621-1628
This paper gives a method to construct rigid spaces, which is similar to the method used to construct toric schemes. 相似文献
189.
Lattice Boltzmann simulation on thermal performance of composite phase change material based on Voronoi models
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
《中国物理 B》2021,30(10):104401-104401
Phase change materials(PCMs) are important for sustaining energy development. For the thermal performance enhancement, the composite PCM with metal foam reconstructed by the Voronoi method is investigated in this work. The lattice Boltzmann method(LBM) is used to analyze the melting process on a pore scale. The melting interface evolution and temperature contour of the composite PCM are explored and compared with those of pure PCM. Moreover, structure parameters including the pore density, porosity and irregularity are investigated comprehensively, indicating that the additive of metal foam strengthens the melting performance of PCM obviously. Compared with pure PCM, the composite PCM has quick rates of the melting front evolution and heat transfer. The heat conduction plays a great role in the whole melting process since the convection is weakened for the composite PCM. To improve the melting efficiency, a larger pore density and smaller irregularity are recommended in general. More significantly, a suitable porosity is determined based on the requirement for the balance between the melting rate and heat storage capacity in practical engineering. 相似文献
190.