全文获取类型
收费全文 | 1448篇 |
免费 | 43篇 |
国内免费 | 8篇 |
专业分类
化学 | 852篇 |
晶体学 | 9篇 |
力学 | 63篇 |
数学 | 86篇 |
物理学 | 489篇 |
出版年
2023年 | 26篇 |
2022年 | 36篇 |
2021年 | 51篇 |
2020年 | 51篇 |
2019年 | 44篇 |
2018年 | 39篇 |
2017年 | 40篇 |
2016年 | 51篇 |
2015年 | 39篇 |
2014年 | 54篇 |
2013年 | 119篇 |
2012年 | 99篇 |
2011年 | 126篇 |
2010年 | 55篇 |
2009年 | 46篇 |
2008年 | 73篇 |
2007年 | 70篇 |
2006年 | 69篇 |
2005年 | 53篇 |
2004年 | 38篇 |
2003年 | 33篇 |
2002年 | 29篇 |
2001年 | 17篇 |
2000年 | 14篇 |
1999年 | 9篇 |
1998年 | 13篇 |
1997年 | 14篇 |
1996年 | 21篇 |
1995年 | 17篇 |
1994年 | 16篇 |
1993年 | 9篇 |
1992年 | 14篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 7篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 7篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1969年 | 2篇 |
排序方式: 共有1499条查询结果,搜索用时 0 毫秒
161.
The 6.4 GHz ECR ion source that was indigenously developed a few years ago has been operating continuously for injecting oxygen
and neon beams to the cyclotron since 1997. VEC-ECR is a single stage high magnetic field ion source provided with a negatively
biased electron repeller placed on the axis, near the injection mirror point. The supply of cold electrons and use of low
mass mixing gas improve the stability of ECR plasma. Very recently, the effect of aluminum oxide coating on the copper plasma
chamber wall has been studied. The plasma chamber wall was coated with aluminum by vacuum evaporation method and then exposed
to oxygen gas to form aluminum oxide. It was noticed that the process substantially shifts the charge state distribution to
the higher charge state with an enhancement of ion current by an order of magnitude. With the aluminized plasma chamber, the
VEC-ECR can now produce 12 μA of O7+, 6.5 μA of Ar12+, 1.5 μA of Kr20+ and 1.0 μA of Xe31+. 相似文献
162.
K. G. Chakraborty 《Zeitschrift für Physik A Hadrons and Nuclei》1974,268(2):179-182
In this paper the effect of biquadratic exchange on Curie temperature has been discussed on the basis of double-time temperature-dependent Green-function formalism with the utilization of Callen decoupling scheme. Calculation has been done for a spin-1 bcc Heisenberg ferromagnet by the method of Flax and Raich and it has been observed that the variation of Curie temperature with the biquadratic exchange parameter α obeys a law prescribed by the previous authors. 相似文献
163.
D K Chakraborty 《Pramana》1988,30(5):371-374
The energy of an electron in circular orbits around a proton in Schwarzschild geometry has been investigated and is found
to be red shifted. The electrical dipole moment of such a system is also estimated. 相似文献
164.
K. G. Chakraborty 《Zeitschrift für Physik B Condensed Matter》1984,55(3):231-234
The statistical mechanics of a spin-one Bethe lattice is discussed. The exact expression for Curie temperature is derived using a Bethe-Peierls approximations. The effect of the inclusion of a single-spin anisotropy to each Ising model of the lattice is also studied. It is seen that under certain situations a first-order phase transition appears. 相似文献
165.
T. Chakraborty K. Niemel P. Pietilinen 《Physica E: Low-dimensional Systems and Nanostructures》1998,1(1-4)
We investigate the properties of a system of interacting electrons in a narrow channel in the quantum Hall effect regime. We find that an increase in the strength of the Coulomb interaction causes abrupt changes in the width of the charge-density profile of translationally invariant states. The resulting phase diagram includes many of the stable odd-denominator states and also a novel fractional quantum Hall state at lowest half-filled Landau level. The collective modes evaluated at
and at
reveal soft modes in between the translationally invariant states in the phase diagram.
1997 Elsevier Science B.V. All rights reserved. 相似文献
166.
Literature study of microwave-assisted digestion using electrothermal atomic absorption spectrometry
R. Chakraborty A. K. Das M. L. Cervera M. de la Guardia 《Fresenius' Journal of Analytical Chemistry》1996,355(2):99-111
The literature on the use of microwave-assisted digestion procedures for subsequent sample analysis by means of electrothermal atomic absorption spectrometry (ETAAS) is reviewed. The literature survey reveals that this digestion technique has been applied mainly for biological materials. The elements most extensively determined by this method are cadmium and lead followed by copper, chromium, nickel and iron. The microwave digestion conditions, ETAAS furnace programmes and analytical details of the developed methodologies have been carefully revised. 相似文献
167.
Frederick E. Ziegler Paul J. Gilligan Utpal R. Chakraborty 《Tetrahedron letters》1979,20(36):3371-3374
D-Glucose has been converted into its functionalized derivative a synthon (C1–C6) of the carbomycin macrolide antibiotics. 相似文献
168.
169.
Tapash Chakraborty 《Physics letters. [Part B]》1978,77(1):6-8
We calculate the model energy of nuclear matter within the FIY expansion scheme. Numerical results are presented for two semi-realistic central potentials and a state independent correlation function which is suitably constrained for good cluster convergence. 相似文献
170.
A calculation for the inner-shell ionization problems is made in a new approach. Results are compared with measured values for doubly and triply differential cross sections and improvements are noticed. 相似文献