全文获取类型
收费全文 | 304320篇 |
免费 | 26244篇 |
国内免费 | 17546篇 |
专业分类
化学 | 177472篇 |
晶体学 | 4731篇 |
力学 | 13494篇 |
综合类 | 31篇 |
数学 | 33534篇 |
物理学 | 118848篇 |
出版年
2021年 | 2411篇 |
2020年 | 3100篇 |
2019年 | 3793篇 |
2018年 | 4270篇 |
2017年 | 4952篇 |
2016年 | 6878篇 |
2015年 | 5555篇 |
2014年 | 6740篇 |
2013年 | 15201篇 |
2012年 | 13037篇 |
2011年 | 16047篇 |
2010年 | 15459篇 |
2009年 | 15375篇 |
2008年 | 12559篇 |
2007年 | 11925篇 |
2006年 | 11027篇 |
2005年 | 10579篇 |
2004年 | 10586篇 |
2003年 | 9110篇 |
2002年 | 8612篇 |
2001年 | 9729篇 |
2000年 | 7321篇 |
1999年 | 6306篇 |
1998年 | 5084篇 |
1997年 | 4800篇 |
1996年 | 5163篇 |
1995年 | 5189篇 |
1994年 | 5206篇 |
1993年 | 5181篇 |
1992年 | 5316篇 |
1991年 | 4827篇 |
1990年 | 4458篇 |
1989年 | 4508篇 |
1988年 | 4525篇 |
1987年 | 3880篇 |
1986年 | 3799篇 |
1985年 | 4322篇 |
1984年 | 4386篇 |
1983年 | 3113篇 |
1982年 | 3664篇 |
1981年 | 3545篇 |
1980年 | 3317篇 |
1979年 | 3448篇 |
1978年 | 3458篇 |
1977年 | 3585篇 |
1976年 | 3756篇 |
1975年 | 2824篇 |
1974年 | 2762篇 |
1973年 | 2937篇 |
1972年 | 2195篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
The changes in the magnetization of yttrium iron garnet (YIG) when irradiated by a pulsed neodymium laser beam with wavelength
λ=1.06 μm are investigated. Measurements are performed in the temperature range from 100 K to 600 K in various external magnetic
fields. YIG single crystals grown along the crystallographic (100), (110), and (111) directions are chosen so that the external
anisotropy of the indicated processes can be determined. Characteristic temperature intervals dominated by different mechanisms
of variation of the magnetization under the influence of a laser pulse are discussed.
Fiz. Tverd. Tela (St. Petersburg) 39, 1263–1266 (July 1997) 相似文献
12.
L. K. Aminov I. N. Kurkin D. A. Lukoyanov K. P. Chernov 《Physics of the Solid State》1997,39(8):1184-1186
Results are reported for measurements of the spin-lattice relaxation times of E′1 centers in quartz glass, produced by neutron irradiation, with the measurements made at two frequencies 9.25 and 24.0 GHz
over a wide temperature interval 1.5–300 K. The experimental data are interpreted on the basis of interaction mechanisms of
the spins with two-level systems with excitation energies ∼6, ∼26, and ∼420 cm−1. A small modification of the existing theory allows us to explain a number of features of the observed temperature and frequency
dependence of the relaxation rate. The results are compared with the data available in the literature on spin-lattice relaxation
of irradiation centers in crystalline quartz and quartz glass.
Fiz. Tverd. Tela (St. Petersburg) 39, 1335–1337 (August 1997) 相似文献
13.
Yoshiaki Murata Cheng-Huang Lin Totaro Imasaka 《Fresenius' Journal of Analytical Chemistry》1993,346(6-9):543-544
Summary A supersonic jet spectrum of 9,10-dichloroanthracene is measured by stimulated-emission-pumping fluorescence dip spectrometry and conventional fluorescence spectrometry. The performance obtained is compared for these spectrometric methods, providing same information concerned with the energy level of the ground state. The former is more preferential for measurement of a high-resolution spectrum, since the spectral resolution is determined by the linewidth of the dumping laser. On the other hand, the latter is more preferential for measurement with better sensitivity at the expense of the spectral resolution, since the fluorescence throughput can be improved by increasing the slit width of the monochromator.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday 相似文献
14.
15.
16.
17.
18.
S. O. Kolusheva B. A. Salakhutdinov T. F. Aripov L. P. Vernon 《Chemistry of Natural Compounds》1994,29(4):523-525
It has been shown by the ESR of spin probes that thionin initially interacts with with negatively charged membranes electrostatically and then passes into the membranes to a depth comparable with the length of the hydrophobic sections of the protein loops.Institute of Bioorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent. Brigham Young University, Provo, Utah, USA. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 594–597, July–August, 1993. 相似文献
19.
Twelve series of linear oligomers of four different degrees of polymerization (xn = 8.77−41.55), having a common perfluorinated random copolymeric chain as molecular body and two equal foreign end units of one of the types listed in Table 1, have been synthesized by derivatization of base samples of one of them having a diolic---CH2OH functionality. The glass transition temperature Tg of all the series was measured and thus examined as a function of xn. A clear end unit effect is observed, dominantly determined in every series by chemical nature and structure of the end units, quantitatively expressed at any xn by different positive or negative Tg deviations from the common asymptotic Tg∞ value. The results are also discussed in terms of copolymer end effect and of relation between Tg and end copolymeric composition. 相似文献
20.
To investigate local ordering and segregation phenomenon in a Ni91Pt9-alloy after sputtering and annealing a 3D optical atom probe (OAP) has been used. The specimen tips have been prepared from polycrystalline samples. To sputter the samples a separate preparation chamber with a scannable Ar-sputter-gun is connected to the OAP vessel. When necessary, the sample can be electrically heated to induce segregation and cure the altered layer. After a heat treatment of a Ni91 at. %Pt 9 at.% specimen at 1100 K the surface of a (111)-oriented specimen is enriched in platinum by a factor of two in relation to the bulk. The phenomenon of short-range ordering has been investigated on the surface and in the subsurface volume. A 3D reconstruction of this annealed NiPt specimen shows regions with high concentration of platinum that gives an indication at short-range ordering. Uniform sputtering of the tip without a heat treatment induces a decisive depletion of Pt on the surface and the following subatomic layers. The atom-probe results of specimens in thermal equilibrium are in close agreement to further surface sensitive results obtained from Ion Scattering Spectroscopy (ISS) and Auger Electron Spectroscopy (AES). 相似文献