全文获取类型
收费全文 | 2919篇 |
免费 | 115篇 |
国内免费 | 6篇 |
专业分类
化学 | 2173篇 |
晶体学 | 42篇 |
力学 | 34篇 |
数学 | 128篇 |
物理学 | 663篇 |
出版年
2023年 | 17篇 |
2022年 | 20篇 |
2021年 | 30篇 |
2020年 | 45篇 |
2019年 | 67篇 |
2018年 | 33篇 |
2017年 | 30篇 |
2016年 | 79篇 |
2015年 | 65篇 |
2014年 | 73篇 |
2013年 | 148篇 |
2012年 | 158篇 |
2011年 | 160篇 |
2010年 | 112篇 |
2009年 | 109篇 |
2008年 | 168篇 |
2007年 | 157篇 |
2006年 | 148篇 |
2005年 | 140篇 |
2004年 | 148篇 |
2003年 | 112篇 |
2002年 | 110篇 |
2001年 | 78篇 |
2000年 | 55篇 |
1999年 | 31篇 |
1998年 | 27篇 |
1997年 | 21篇 |
1996年 | 38篇 |
1995年 | 14篇 |
1994年 | 22篇 |
1993年 | 22篇 |
1992年 | 25篇 |
1991年 | 31篇 |
1990年 | 29篇 |
1989年 | 26篇 |
1988年 | 27篇 |
1987年 | 28篇 |
1986年 | 21篇 |
1985年 | 44篇 |
1984年 | 38篇 |
1983年 | 28篇 |
1982年 | 26篇 |
1981年 | 32篇 |
1980年 | 27篇 |
1979年 | 38篇 |
1978年 | 32篇 |
1977年 | 16篇 |
1976年 | 31篇 |
1975年 | 20篇 |
1974年 | 14篇 |
排序方式: 共有3040条查询结果,搜索用时 15 毫秒
11.
12.
A. Noda S. Nakamura Y. Iwashita S. Sakabe M. Hashida T. Shirai S. Shimizu H. Tongu H. Ito H. Souda A. Yamazaki M. Tanabe H. Daido M. Mori M. Kado A. Sagisaka K. Ogura M. Nishiuchi S. Orimo Y. Hayashi A. Yogo S. Bulanov T. Esirkepov A. Nagashima T. Kimura T. Tajima T. Takeuchi K. Matsukado A. Fukumi Z. Li 《Laser Physics》2006,16(4):647-653
In order to widely spread out particle beams utilized in cancer therapy, laser-produced ions are developed as the injection beam for an ion synchrotron dedicated for cancer therapy. Such a laser ion source is expected to contribute largely to the realization of compactness of the size and low cost of the cancer therapy accelerator. The energy spectrum of the laser-produced ions, however, has no peak, but their intensities decrease exponentially according to the increase of the energy. For the purpose of modifying such a situation, we have proposed a scheme to rotate the beam in the longitudinal phase space with the use of the RF electric field, which is phase-adjusted with the pulse laser. We aim for a reduction of the energy spread of ± 5% selected by an energy analyzer and slits to ±1% by such phase rotation. For this purpose, a quarter wavelength resonator with two gaps with the same resonant frequency as the source laser has already been fabricated, together with its RF power source. The above phase rotation system and its recent experimental realization are presented. 相似文献
13.
In this paper, we study Schrödinger type operator on a Riemannian manifold. Under some assumptions on a potential function, we characterize the domain of the square root of the Schrödinger type operator on L p space. In the proof, the defective intertwining properties and the Littlewood-Paley inequalities play important roles. 相似文献
14.
15.
Adsorption process of methylchloride (CH3Cl) on the GaAs (0 0 1)-2 × 4 surface was studied by a scanning tunnelling microscopy (STM) measurement. The arsenic rich 2 × 4 surface, which was prepared by molecular beam epitaxy (MBE), was exposed to a supersonic molecular beam of CH3Cl with a kinetic energy of 0.06 eV. New bright spots appeared on the CH3Cl exposed surface. They were largely observed at the “B-type” step edge and divided into two types according to their locations. It was suggested that new spots were due to weakly adsorbed CH3Cl molecules without any dissociation. The adsorption mechanism of CH3Cl molecule was also studied by an ab initio Hartree-Fock calculation, which explained the experimental results well. 相似文献
16.
Hoon Kim Toshihiko Koseki Tomohiro Ohta Hiroshi Sato Yukihiro Shimogaki 《Applied Surface Science》2006,252(11):3938-3942
The adhesion of Cu on Ru substrates with different crystal orientations was evaluated. The crystal orientation of sputter deposited Ru could be changed from (1 0 0) to (0 0 1) by annealing at 650 °C for 20 min. The adhesion of Cu was evaluated by the degree of Cu agglomeration on Ru. Cu films on annealed Ru films with the (0 0 1) crystal orientation showed 28% lower RMS values and 50% lower Ru surface coverage than Cu as-deposited on Ru having the (1 0 0) crystal orientation after annealing at 550 °C for 30 min, which suggest that Cu wettability on the Ru(0 0 1) was better than that on the Ru(1 0 0) plane. The low lattice misfit of 4% between Cu(1 1 1) and Ru(0 0 1) may be the reason for this good adhesion property. 相似文献
17.
Tomohiro Kyotani Sonoko Kakui Takehito Mizuno Naoto Shimotsuma Soushi Inoue Junji Saito 《Analytical sciences》2006,22(7):1031-1034
A zeolite NaA (LTA) membrane supported by an alumina porous support tube for pervaporation (PV) dehydration of ethanol was characterized by transmission electron microscopy (TEM) using a focused ion beam (FIB) thin-layer specimen preparation technique and by Fourier transform infrared attenuated total reflectance method (FTIR-ATR) using a diamond prism as the waveguide. FIB-TEM clearly presented cross-section images up to about 15 microm depth from the membrane surface. FTIR-ATR monitored the Si-O asymmetric stretching vibration spectrum. The Si-O spectrum was compared with the TEM image and their relationships were discussed. By combining the two methods, we could study the thickness of surface LTA crystals, the grain boundary, the LTA/alumina interface structure and the crystallinity and density of materials inside of the alumina porous support. Consequently, fine structure changes of the LTA membrane corresponding to the hydrothermal synthesis condition could be sensitively detected. 相似文献
18.
We calculate s-wave and p-wave absorptive pion-nucleus optical potentials assuming that a pion is absorbed by a pair of nucleons. Employing a model which takes into account both a single nucleon absorption with nucleon-nucleon correlations and rescattering, we obtain simple analytic expressions for Im B0 sid Im C0 of the pion-nucleus optical potential. The off-shell effect on the s-wave pion absorption is examined and shown to be strongly modified by short range correlations. The result for the p-wave absorptive part Im C0 clearly shows the importance of the tensor correlations. The enhanced nn emission after π? absorption is shown to be related with a large p-wave πN scattering length a33 via the tensor correlations. 相似文献
19.
Y. Masuda K. Asahi J. Kura Y. Mori H. Sato H. M. Shimizu 《Hyperfine Interactions》1992,74(1-4):149-157
An experimental scheme of the spin detailed balance in polarized neutron transmission through a polarized nuclear target is
discussed for the T-violation test. The value of the spin detailed balance is estimated by using the data of the scattering
amplitudes. The nuclear polarizations of proton,3He and139La are discussed for the T-violation experiment. 相似文献
20.
Tomohiro Shirai 《Optical Review》2004,11(5):312-319
Spatial coherence of the field modified by low-order adaptive optics is analyzed to establish a theoretical basis for the recent idea of using adaptive optics as a spatial coherence modifier. In this context low-order adaptive optics has the ability to correct some of the low-order aberrations specified by Zernike polynomials. The initial field to be modified is assumed to be a spatially partially coherent one resulting from phase disturbance. It is demonstrated, as in the previous study, that low-order adaptive optics serves to enhance the spatial coherence of the resultant field and that the effect of the enhancement becomes stronger as the spatial coherence of the initially partially coherent field increases. Potential applications of low-order adaptive optics as a spatial coherence modifier are briefly discussed. 相似文献