全文获取类型
收费全文 | 530863篇 |
免费 | 3589篇 |
国内免费 | 1113篇 |
专业分类
化学 | 242574篇 |
晶体学 | 8153篇 |
力学 | 30106篇 |
综合类 | 3篇 |
数学 | 81266篇 |
物理学 | 173463篇 |
出版年
2020年 | 4567篇 |
2019年 | 5434篇 |
2018年 | 12668篇 |
2017年 | 13027篇 |
2016年 | 12708篇 |
2015年 | 5660篇 |
2014年 | 9566篇 |
2013年 | 20068篇 |
2012年 | 18438篇 |
2011年 | 26427篇 |
2010年 | 18864篇 |
2009年 | 19105篇 |
2008年 | 24146篇 |
2007年 | 26295篇 |
2006年 | 16336篇 |
2005年 | 17618篇 |
2004年 | 15191篇 |
2003年 | 14434篇 |
2002年 | 13477篇 |
2001年 | 13240篇 |
2000年 | 10508篇 |
1999年 | 7807篇 |
1998年 | 7018篇 |
1997年 | 6827篇 |
1996年 | 6503篇 |
1995年 | 5780篇 |
1994年 | 5754篇 |
1993年 | 5853篇 |
1992年 | 6024篇 |
1991年 | 6459篇 |
1990年 | 6248篇 |
1989年 | 6211篇 |
1988年 | 5986篇 |
1987年 | 5951篇 |
1986年 | 5536篇 |
1985年 | 6958篇 |
1984年 | 7421篇 |
1983年 | 6105篇 |
1982年 | 6498篇 |
1981年 | 6150篇 |
1980年 | 5855篇 |
1979年 | 6338篇 |
1978年 | 6528篇 |
1977年 | 6469篇 |
1976年 | 6625篇 |
1975年 | 6121篇 |
1974年 | 5993篇 |
1973年 | 6239篇 |
1972年 | 4828篇 |
1971年 | 4214篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
791.
L. S. Azhgirey V. V. Arkhipov S. V. Afanasiev V. K. Bondarev V. N. Zhmyro L. S. Zolin V. I. Ivanov A. Yu. Isupov A. A. Kartamyshev V. A. Kashirin V. I. Kolesnikov V. A. Kuznetsov V. P. Ladygin N. B. Ladygina A. G. Litvinenko S. G. Reznikov P. A. Rukoyatkin A. Yu. Semenov I. A. Semenova G. D. Stoletov G. Filipov A. N. Khrenov N. P. Yudin 《Physics of Atomic Nuclei》2003,66(4):690-699
The invariant differential cross section, the tensor analyzing power A yy , and the vector analyzing power A y for the reaction 9Be(d, p)X are measured at an initial deuteron momentum of 4.5 GeV/c and a proton detection angle of about 80 mrad. The data obtained for the differential cross section are consistent with the results of measurements at 3.5 and 5.78 GeV/c and a proton emission angle of 2.5°. The values found for the tensor analyzing power A yy are compared with similar data obtained previously for the deuteron-fragmentation process occurring on a carbon target at various values of the initial deuteron momentum and leading to proton emission at zero angle. The data on the differential cross section for the reaction 9Be(d, p)X can be satisfactorily described within the relativistic impulse approximation by using standard deuteron wave functions; however, the approach based on this conceptual framework proves to be inadequate in dealing with data on the tensor analyzing power. These results indicate that it is necessary either to change the method for describing the relativistic deuteron or to take into account additional mechanisms. 相似文献
792.
793.
Nickel complexes 1–4 ligated with 2,9-disubstituted-1,10-phenanthroline were synthesized and characterized by FT-IR spectra and elemental analysis.
The molecular structure of complex 2 was confirmed by X-ray crystal diffraction analysis. Activated with methylaluminoxane (MAO), those complexes showed moderate
activities for ethylene oligomerization.
Published in Kinetika i Kataliz, 2007, Vol. 48, No. 5, pp. 710–714.
This article was submitted by the authors in English. 相似文献
794.
Silica@copper (SiO2@Cu) core–shell nanoparticles were synthesized and well characterized by XRD, TEM, AFM, XPS, UV/Vis, TGA–MS, and ICP–AES techniques. The synthesized SiO2@Cu core–shell nanoparticles were employed as catalysts for the conjugate addition of amines to α,β‐unsaturated compounds in water to obtain β‐amino carbonyl compounds in excellent yields in shorter reaction times. Furthermore, the catalyst works well for hetero‐Michael addition reactions of heteroatom nucleophiles such as thiols to α,β‐unsaturated compounds. As the reaction is performed in water, it allows for easy recycling of the catalyst with consistent activity. 相似文献
795.
796.
V. P. Ershov D. A. Kas’yanov V. I. Rodchenkov D. A. Sergeev 《Crystallography Reports》2008,53(2):339-343
The growth of the isolated (100) face of a KDP crystal at exposure of the phase boundary to the initial ultrasound field and a standing acoustic wave has been investigated. A significant growth response of this face, exposed to sound normally along the acoustic axis in the near zone of a piston-like half-wave vibrator with f = 20 kHz and tangentially in the pulsed two-frequency (f = 600 and 900 kHz) standing-wave mode, has been revealed. It is shown that the mechanisms of mass exchange enhancement in these acoustic modes are different. The results obtained show a fundamental possibility of controlling crystal growth and dissolution by varying the parameters of inhomogeneous acoustic field. 相似文献
797.
A. P. Voronov G. N. Babenko V. M. Puzikov A. D. Roshal’ V. I. Salo 《Crystallography Reports》2008,53(4):708-712
The features of doping of KDP crystals with cerium ions and organocerium complexes with alizarin complexon and arsenazo III have been investigated. It is established that “direct” doping by introducing cerium salts into the initial solution cannot be implemented. The effect of organometallic complexes of cerium on the crystal growth has been studied. Organocerium complexes predominantly enter the prismatic or pyramidal growth sectors. It is shown that the complex arsenazo III + Ce blocks the growth of the prismatic sector. Cerium-doped KDP crystals exhibit a photoluminescence band peaking at the wavelength λmax= 350 nm. 相似文献
798.
N. A. Anurova V. A. Blatov G. D. Ilyushin O. A. Blatova A. K. Ivanov-Shitz L. N. Demyanets 《Crystallography Reports》2008,53(6):930-936
A new method was developed for studying voids and channels in crystal structures based on the Voronoi-Dirichlet partition
of crystal space, and 822 structurally characterized ternary compounds Li
p
X
q
O
r
were analyzed for the first time. For these compounds, the dimensionality was determined and the migration patterns of channel
systems capable of providing lithium-ion transport were constructed. The calculated coordinates of lithium atoms in the centers
of the voids are consistent (within 0.4 ?) with the known structural data. Among these compounds, 113 compounds have infinite
channel systems, 60 compounds (18 structural types, STs) have been described earlier in the literature as solid electrolytes,
and 53 compounds (23 STs) can be considered as potential one-, two-, or three-dimensional ionic conductors (13, 3, and 7 STs,
respectively).
Original Russian Text ? N.A. Anurova, V.A. Blatov, G.D. Ilyushin, O.A. Blatova, A.K. Ivanov-Shitz, L.N. Dem’yanets, 2008,
published in Kristallografiya, 2008, Vol. 53, No. 6, pp. 987–993. 相似文献
799.
K. Morigaki K. Takeda H. Hikita C. Ogihara P. Roca i Cabarrocas 《Journal of Non》2008,354(19-25):2131-2134
Our model for light-induced defect creation in hydrogenated amorphous silicon is applied to its kinetics, i.e., the growing curve of light-induced dangling bond density as a function of illumination time, which is fitted to a stretched exponential function. Two parameters β and τ involved in the function are estimated as functions of saturated dangling bond density in terms of our model. These are compared with two experimental results, i.e., our results obtained from ESR measurements and Shimakawa et al.’s results obtained from photoconductivity measurements. The saturated dangling bond density is also measured as a function of the generation rate of free carriers. The experimental results are compared with calculated results and discussed. 相似文献
800.
O. M. Ostrikov 《Mechanics of Solids》2008,43(5):793-797
We propose a dislocation model of a nanotwin, which is used to calculate the stress fields in the nanotwin. We consider the role of these stresses in the process of interdislocation interaction and nanotwin growth. 相似文献