全文获取类型
收费全文 | 17182篇 |
免费 | 3379篇 |
国内免费 | 2858篇 |
专业分类
化学 | 10038篇 |
晶体学 | 184篇 |
力学 | 1535篇 |
综合类 | 256篇 |
数学 | 1802篇 |
物理学 | 9604篇 |
出版年
2024年 | 57篇 |
2023年 | 218篇 |
2022年 | 479篇 |
2021年 | 609篇 |
2020年 | 768篇 |
2019年 | 598篇 |
2018年 | 579篇 |
2017年 | 668篇 |
2016年 | 789篇 |
2015年 | 681篇 |
2014年 | 980篇 |
2013年 | 1502篇 |
2012年 | 1019篇 |
2011年 | 1124篇 |
2010年 | 980篇 |
2009年 | 1187篇 |
2008年 | 1219篇 |
2007年 | 1223篇 |
2006年 | 1187篇 |
2005年 | 926篇 |
2004年 | 854篇 |
2003年 | 795篇 |
2002年 | 649篇 |
2001年 | 579篇 |
2000年 | 555篇 |
1999年 | 485篇 |
1998年 | 431篇 |
1997年 | 333篇 |
1996年 | 283篇 |
1995年 | 238篇 |
1994年 | 212篇 |
1993年 | 168篇 |
1992年 | 139篇 |
1991年 | 143篇 |
1990年 | 92篇 |
1989年 | 87篇 |
1988年 | 80篇 |
1987年 | 70篇 |
1986年 | 67篇 |
1985年 | 59篇 |
1984年 | 48篇 |
1983年 | 25篇 |
1982年 | 39篇 |
1981年 | 37篇 |
1980年 | 31篇 |
1979年 | 33篇 |
1978年 | 14篇 |
1977年 | 22篇 |
1976年 | 15篇 |
1974年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
211.
Y.K. Gambhir J.P. Maharana C.S. Warke 《The European Physical Journal A - Hadrons and Nuclei》1998,3(3):255-262
The existence of broken pseudo-spin symmetry in the Pb nucleus has been studied in the relativistic mean field approach using
realistic Lagrangian parameters. Its relationship to spin orbit splitting and the vanishingly small surface delta character
of the mean spin orbit potential are investigated. In the 208Pb nucleus the broken pseudo-spin doublets are found to exist above the neutron (proton) Fermi surfaces.
Received: 16 April 1998 / Revised version: 26 June 1998 相似文献
212.
P. Galatola M. Zelazna I. Lelidis 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,2(1):51-56
We study the surface behavior of a semi-infinite smectogenic sample bounded by a solid wall, in the presence of an external
electric field. Our analysis is performed in the framework of a Landau-de Gennes theory. For the sake of simplicity, we consider
only the case in which, in the absence of field and surfaces, a direct isotropic to smectic-A transition occurs, while in
the presence of the electric field a nonspontaneous nematic phase appears. Two new surface phases are identified, namely a
parasmectic and a surface-induced smectic phase. The shifts in the transition temperatures and the critical behavior of the surface states are analyzed.
Received: 25 August 1997 / Accepted: 23 January 1998 相似文献
213.
超重元素(新核素)合成研究进展情况分析和展望 总被引:2,自引:0,他引:2
本文在介绍和分析国际、国内在超重元素(新核素)合成实验研究与理论研究进展情况的基础上对我国今后如何从理论与实验的结合上开展超重元素(核)合成研究工作提出一些看法和建议,提供讨论。 相似文献
214.
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
215.
216.
T. González-Lezana G. Delgado-Barrio P. Villarreal F.X. Gadéa 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(2):227-232
The stabilization method is applied to the case of interacting resonances in the photo-dissociation of van der Waals clusters
composed by a rare gas atom bound to a dihalogen molecule. The study of an illustrative two-dimensional model consisting in
a T-shaped NeI2 molecule shows the adequacy of the method whenever the projection of the stabilization wave functions on the assumed prepared
initial state is accounted for. The agreement of the fragmentation cross-sections with some previous results using the effective
resolvent method and accurate close-coupling calculations is excellent. The method reveals its utility as a complementary
tool since allows, through the analysis of the stabilization wave function in terms of zero-order levels, a precise characterization
of the resonant states involved.
Received 5 April 2002 / Received in final form 24 May 2002 Published online 19 July 2002 相似文献
217.
218.
X.S. Cai 《Applied Surface Science》2006,252(8):2776-2781
SiGe/Si quantum wells (QWs) with different Boron doping concentrations were grown by molecular beam epitaxy (MBE) on p-type Si(1 0 0) substrate. The activation energies of the heavily holes in ground states of QWs, which correspond to the energy differences between the heavy hole ground states and Si valence band, were measured by admittance spectroscopy. It is found that the activation energy in a heavily doped QW increases with doping concentration, which can be understood by the band alignment changes due to the doping in the QWs. Also, it is found that the activation energy in a QW with a doping concentration of 2 × 1020 cm−3 becomes larger after annealing at a temperature of 685 °C, which is attributed to more Boron atoms activation in the QW by annealing. 相似文献
219.
A way of determining the flexibility of wood-pulp fibres is developed, which involves i) a precise measurement of the topology
of single-fibres by using a confocal laser scanning microscope and ii) the measurement of the elastic modulus of the fibres
by using a single-fibre fatigue cell. Reported in this paper are the initial results of tests carried out on black spruce
fibres, which have been subjected to three different levels of mechanical refining energy, namely ∼1100, 2300, and 3500 kWh/t.
It is found that the fibre flexibility rises significantly between the first and second energy levels, but it does not change
to the same degree between the second and third ones. The described procedure of measuring the flexibility of fibres may be
used to establish the appropriate refiner energy necessary for the production of a specific grade of paper.
Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 42, No. 1, pp. 115–128, January–February, 2006. 相似文献
220.
当离子蒸气冷凝形成团簇时,其结构表现出特定的规律。文中对不同大小不同形状的氯化钠团簇结构与结合能进行了计算,以求揭示离子蒸气冷凝形成团簇的一些规律,并与实验结果进行对照。 相似文献