全文获取类型
收费全文 | 1236篇 |
免费 | 23篇 |
国内免费 | 3篇 |
专业分类
化学 | 591篇 |
晶体学 | 17篇 |
力学 | 63篇 |
数学 | 112篇 |
物理学 | 479篇 |
出版年
2022年 | 11篇 |
2021年 | 11篇 |
2020年 | 20篇 |
2019年 | 25篇 |
2018年 | 18篇 |
2017年 | 24篇 |
2016年 | 41篇 |
2015年 | 21篇 |
2014年 | 35篇 |
2013年 | 59篇 |
2012年 | 70篇 |
2011年 | 78篇 |
2010年 | 62篇 |
2009年 | 41篇 |
2008年 | 72篇 |
2007年 | 73篇 |
2006年 | 58篇 |
2005年 | 48篇 |
2004年 | 35篇 |
2003年 | 37篇 |
2002年 | 41篇 |
2001年 | 22篇 |
2000年 | 24篇 |
1999年 | 18篇 |
1998年 | 18篇 |
1997年 | 15篇 |
1996年 | 17篇 |
1995年 | 14篇 |
1994年 | 13篇 |
1993年 | 19篇 |
1992年 | 11篇 |
1991年 | 4篇 |
1990年 | 11篇 |
1989年 | 18篇 |
1988年 | 6篇 |
1987年 | 18篇 |
1986年 | 7篇 |
1985年 | 14篇 |
1984年 | 12篇 |
1983年 | 13篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1975年 | 4篇 |
1972年 | 4篇 |
1960年 | 4篇 |
1954年 | 5篇 |
排序方式: 共有1262条查询结果,搜索用时 265 毫秒
1.
The dependence of the beam propagation factor (M
2 parameter) with the absorbed pump power in the case of monolithic microchip laser under face-cooled configuration is extensively
studied. Our investigations show that the M
2 parameter is related to the absorbed pump power through two parameters (α and β) whose values depend on the laser material properties and laser configuration. We have shown that one parameter arises due
to the oscillation of higher order modes in the microchip cavity and the other parameter accounts for the spherical aberration
associated with the thermal lens induced by the pump beam. Such dependency of M
2 parameter with the absorbed pump power is experimentally verified for a face-cooled monolithic microchip laser based on Nd3+ -doped GdVO4 crystal and the values of α and β parameters were estimated from the experimentally measured data points. 相似文献
2.
CV Tomy D Pal SS Banerjee S Ramakrishnan AK Grover S Bhattacharya MJ Higgins G Balakrishnan McK Paul 《Pramana》2002,58(5-6):925-935
The weakly pinned single crystals of the hexagonal 2H-NbSe2 compound have emerged as prototypes for determining and characterizing the phase boundaries of the possible order-disorder
transformations in the vortex matter. We present here a status report based on the ac and dc magnetization measurements of
the peak effect phenomenon in three crystals of 2H-NbSe2, in which the critical current densities vary over two orders of magnitude. We sketch the generic vortex phase diagram of
a weakly pinned superconductor, which also utilizes theoretical proposals. We also establish the connection between the metastability
effects and pinning. 相似文献
3.
Apurba Bhattacharya Nitin C. Patel Michael Peddicord Luca Parlanti John A. Grosso 《Tetrahedron letters》2006,47(30):5341-5343
An efficient, one-pot, phase transfer N-amination technology was developed. The protocol utilizes chloramine, an inexpensive and safe electrophilic aminating agent potentially viable for commercial manufacturing. 相似文献
4.
V Ravindran Pankaj Agrawal Rahul Basu Satyaki Bhattacharya J Blümlein V Del Duca R Harlander D Kosower Prakash Mathews Anurag Tripathi 《Pramana》2006,67(5):983-992
This is the report of the subgroup QCD of Working Group-4 at WHEPP-9. We present the activities that had taken place in the
subgroup and report some of the partial results arrived at following the discussion at the working group meetings. 相似文献
5.
It is shown how the traditional method of neglecting the energy of acoustic phonons and approximating their distribution by the equipartition law leads to significant errors in the phonon growth rate in a many-valley model semiconductor when the lattice temperature is low. 相似文献
6.
Apurba Bhattacharya Nitin C. Patel Ritesh Tichkule Jiejun Wu 《Tetrahedron letters》2006,47(4):565-567
A simple, surfactant-mediated, one-pot, solvent-free dealkylative cleavage of aryl ethers and esters followed by subsequent optional trans-alkylation under essentially neutral conditions has been developed. 相似文献
7.
Heavy ion irradiation in the electronic stopping power region induces macroscopic dimensional change in metallic glasses and introduces magnetic anisotropy in some magnetic materials. The present work is on the irradiation study of ferromagnetic metallic glasses, where both dimensional change and modification of magnetic anisotropy are expected. Magnetic anisotropy was measured using Mössbauer spectroscopy of virgin and irradiated Fe40Ni40B20 and Fe40Ni38Mo4B18 metallic glass ribbons. 90 MeV 127I beam was used for the irradiations. Irradiation doses were 5×1013 and 7.5×1013 ions/cm2. The relative intensity ratios D 23 of the second and third lines of the Mössbauer spectra were measured to determine the magnetic anisotropy. The virgin samples of both the materials display in-plane magnetic anisotropy, i.e., the spins are oriented parallel to the ribbon plane. Irradiation is found to cause reduction in magnetic anisotropy. Near-complete randomization of magnetic moments is observed at high irradiation doses. Correlation is found between the residual stresses introduced by ion irradiation and the change in magnetic anisotropy. 相似文献
8.
Santanu Bhattacharya Basudeb Saha Amitava Dutta Pradyot Banerjee 《Coordination chemistry reviews》1998,170(1):47-74
This review narrates the electron transfer reactions of various nickel(III) and nickel(IV) complexes reported during the period 1981 until today. The reactions have been categorized mainly with respect to the type of nickel complexes. The reactivity of nickel(III) complexes of macrocycles, 2,2′-bipyridyl and 1,10-phenanthroline, peptides and oxime–imine, and of nickel(IV) complexes derived from oxime–imine, oxime and miscellaneous ligands with various organic and inorganic electron donors have been included. Kinetic and mechanistic features associated with such interactions have been duly analyzed. The relevance of Marcus cross-relation equations in the delineation of the electron transfer paths has also been critically discussed. 相似文献
9.
10.