全文获取类型
收费全文 | 946篇 |
免费 | 14篇 |
专业分类
化学 | 384篇 |
晶体学 | 7篇 |
力学 | 38篇 |
数学 | 145篇 |
物理学 | 386篇 |
出版年
2021年 | 17篇 |
2020年 | 17篇 |
2019年 | 11篇 |
2018年 | 33篇 |
2017年 | 36篇 |
2016年 | 47篇 |
2015年 | 15篇 |
2014年 | 35篇 |
2013年 | 44篇 |
2012年 | 44篇 |
2011年 | 40篇 |
2010年 | 34篇 |
2009年 | 31篇 |
2008年 | 36篇 |
2007年 | 26篇 |
2006年 | 24篇 |
2005年 | 19篇 |
2004年 | 18篇 |
2003年 | 14篇 |
2002年 | 21篇 |
2001年 | 21篇 |
2000年 | 16篇 |
1999年 | 8篇 |
1997年 | 11篇 |
1996年 | 15篇 |
1995年 | 9篇 |
1994年 | 12篇 |
1993年 | 8篇 |
1992年 | 12篇 |
1991年 | 12篇 |
1990年 | 12篇 |
1989年 | 12篇 |
1988年 | 8篇 |
1987年 | 9篇 |
1984年 | 7篇 |
1983年 | 8篇 |
1981年 | 16篇 |
1980年 | 7篇 |
1979年 | 14篇 |
1977年 | 14篇 |
1976年 | 12篇 |
1975年 | 14篇 |
1974年 | 15篇 |
1973年 | 21篇 |
1972年 | 8篇 |
1971年 | 13篇 |
1970年 | 12篇 |
1968年 | 7篇 |
1966年 | 7篇 |
1965年 | 8篇 |
排序方式: 共有960条查询结果,搜索用时 15 毫秒
71.
G. V. Shustov A. B. Zolotoi P. N. Belov S. V. Konovalikhin L. O. Atovmyan V. N. Voznesenskii R. G. Kostyanovskii 《Russian Chemical Bulletin》1990,39(8):1651-1657
Solvolysis of 1-tosyloxy-2-1,2,3-triazoline-5,5-dicarboxylic acid esters (1) occurs via elimination of N2 and leads predominantly to N--hydroxylethyl-O-tosylhydroxylamines (II), whose structure was determined unequivocally by x-ray structural analysis. The mechanism of solvolysis of triazolines (I) is discussed, along with the structural characteristics and stabilization factors of the O-tosylhydroxylamine products (II).For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1820–1827, August, 1990. 相似文献
72.
Y. I. Belov S. D. Kitai A. P. Naumov V. A. Rassadovsky M. Y. Yablokov 《Radiophysics and Quantum Electronics》2000,43(3):187-195
We study the physical conditions for balloon-borne radiometric sounding of the humidity height profile in the 3-mm atmospheric
transparency window, an unusual spectral band for such problems, using a balloon drifting in the tropopause. We solve the
inverse problem and discuss the accuracy of reconstruction of the humidity profiles.
Radiophysical Research Institute, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,
Vol. 43, No. 3, pp. 207–216, March 2000 相似文献
73.
A. G. Belov 《Computational Mathematics and Modeling》2008,19(2):230-237
Point estimation issues are investigated for the three-parameter family of compound Poisson distributions. Formulas for parameter
estimators and their covariance matrix are derived by the even-frequency method; the asymptotic efficiency of the estimators
is expressed with an informant in series form. The efficiency of even-frequency estimation is computed and analyzed for the
parameter characteristics.
__________
Translated from Prikladnaya Matematika i Informatika, No. 25, pp. 99–106, 2007. 相似文献
74.
The kinetics of the alternating copolymerization of ethylene with carbon monoxide has been studied in the presence of a palladium catalyst immolized on a polymer support in various media (methanol, toluene, heptane). In the case of hydrocarbon solvents, the activity of the supported catalyst is commensurable with the activity of a homogeneous system in methanol. The melting temperature of the resulting copolymer and its molecular mass depend on the solvent nature. The IR reflectance spectra of the active palladium complex and the ethylene-carbon monoxide copolymer are measured. 相似文献
75.
76.
A new technique is suggested for multimode fiber bandwidth prediction based on a preform profile. It allows one to calculate the output pulse distortion and allows the bandwidth of a fiber to be drawn dependent on the excitation conditions under which it will operate. It is shown that the accuracy of the bandwidth prediction for 1.5- to 2.5-km fibers is about 10%, the bandwidth being 1-1.5 GHz/km. To achieve this accuracy it is necessary that the excitation conditions and differential mode attenuation be exactly reproduced in the calculation. The profile variations along the length should not be considerable. The prediction technique was adapted to the P101 Preform Analyser (York Technology) and can replace alpha-approximation curve-fitting during routine manufacture of multimode preforms. 相似文献
77.
A. Ya. Belov 《Journal of Mathematical Sciences》2008,154(2):125-142
This paper is devoted to relations between the Kurosh problem and the Shirshov height theorem. The central point and main
technical tool is the identity of algebraicity. The main result of this paper is the following. Let A be a finitely generated PI-algebra and Y be a finite subset of A. For any Noetherian associative and commutative ring {ie125-01}, let any factor of R ⊗ A such that all projections of elements from Y are algebraic over π(R) be a Noetherian R-module. Then A has bounded essential height over Y. If, furthermore, Y generates A as an algebra, then A has bounded height over Y in the Shirshov sense.
This paper also contains a new proof of the Razmyslov-Kemer-Braun theorem on radical nilpotence of affine PI-algebras. This
proof allows one to obtain some constructive estimates.
The main goal of the paper is to develop a “virtual operator calculus.” Virtual operators (pasting, deleting, and transfer)
depend not only on an element of the algebra but also on its representation.
__________
Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 13, No. 2, pp. 3–29, 2007. 相似文献
78.
V. R. Flid V. B. Kuznetsov A. A. Grigorev A. P. Belov 《Reaction Kinetics and Catalysis Letters》2000,41(5):604-611
The cyclodimerization of norbornadiene-2,5 (NBD) catalyzed by the systems formed on the basis of bis(ηy3-allyl)nickel and organophosphorus compounds and the process kinetics are studied. The formation rate of all products follows
the overall second-order rate law: first order with respect to the catalyst and NBD. The addition of phosphines and phosphites
substantially decreases the reaction rate compared to that in nickel systems containing no organophosphorus additives. The
influence of the phosphine ligand structure and temperature on the ratio of the reaction products is studied. The blocking
of one coordination site on the nickel atom changes the process kinetics. The loss of two vacancies results in the loss of
the catalytic activity of the system. A mechanism explaining the stoichiometry and composition of the reaction products is
proposed. 相似文献
79.
Anuj R. Shah Jennifer Davidson Matthew E. Monroe Anoop M. Mayampurath William F. Danielson Yan Shi Aaron C. Robinson Brian H. Clowers Mikhail E. Belov Gordon A. Anderson Richard D. Smith 《Journal of the American Society for Mass Spectrometry》2010,21(10):1784-1788
The diverse range of mass spectrometry (MS) instrumentation along with corresponding proprietary and nonproprietary data formats has generated a proteomics community driven call for a standardized format to facilitate management, processing, storing, visualization, and exchange of both experimental and processed data. To date, significant efforts have been extended towards standardizing XML-based formats for mass spectrometry data representation, despite the recognized inefficiencies associated with storing large numeric datasets in XML. The proteomics community has periodically entertained alternate strategies for data exchange, e.g., using a common application programming interface or a database-derived format. However, these efforts have yet to gain significant attention, mostly because they have not demonstrated significant performance benefits over existing standards, but also due to issues such as extensibility to multidimensional separation systems, robustness of operation, and incomplete or mismatched vocabulary. Here, we describe a format based on standard database principles that offers multiple benefits over existing formats in terms of storage size, ease of processing, data retrieval times, and extensibility to accommodate multidimensional separation systems. 相似文献
80.
E. I. Orlova N. E. Novikova A. Gagor I. A. Verin A. Pietraszko D. A. Belov V. I. Voronkova 《Crystallography Reports》2010,55(4):594-601
A series of potassium titanyl phosphate single crystals doped with zinc (KTP: Zn) is grown by spontaneous flux crystallization.
Their properties and the way the additive is implanted in the crystal lattice are studied. The inclusion of zinc atoms in
the KTP structure is evidenced by the data of chemical analysis and the results of studies of electrophysical properties (the
growth of conductivity and increase of relaxation anomalies). Precision X-ray diffraction studies of KTP: Zn single crystals
reveal changes in the channel of the structure which correlate with the physical properties of this crystal series. No substitution
of zinc atoms for titanium, phosphorus, or potassium atoms is found in the structure. Zinc atoms can be located at structural
defects, domain walls, and the crystal surface. 相似文献