全文获取类型
收费全文 | 438篇 |
免费 | 5篇 |
国内免费 | 3篇 |
专业分类
化学 | 210篇 |
力学 | 14篇 |
数学 | 160篇 |
物理学 | 62篇 |
出版年
2024年 | 1篇 |
2022年 | 6篇 |
2021年 | 13篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2018年 | 4篇 |
2017年 | 12篇 |
2016年 | 13篇 |
2015年 | 11篇 |
2014年 | 18篇 |
2013年 | 35篇 |
2012年 | 30篇 |
2011年 | 36篇 |
2010年 | 26篇 |
2009年 | 29篇 |
2008年 | 19篇 |
2007年 | 22篇 |
2006年 | 17篇 |
2005年 | 21篇 |
2004年 | 23篇 |
2003年 | 11篇 |
2002年 | 8篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 1篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1976年 | 2篇 |
1935年 | 1篇 |
排序方式: 共有446条查询结果,搜索用时 15 毫秒
91.
This paper presents an experimental characterization of two sources of calcium carbonate, limestone and calcium carbonate precipitate (CCP) used in wet flue gas desulphurization processes. Characterization of the two carbonate sources was carried out by chemical analysis, IR spectra, thermal behavior, particle size distribution for CCP, BET surface area and absorption capacity of SO2 in calcium carbonate suspensions. The absorption temperature, suspension concentration and carbonate grain size were found to be the most influential parameters in the absorption capacity measurements. 相似文献
92.
Ljubi?a Balanovi? Dragan Manasijevi? Dragana ?ivkovi? Aleksandra Mitovski Nade?da Talijan Du?ko Mini? ?ivan ?ivkovi? 《Journal of Thermal Analysis and Calorimetry》2012,110(1):221-226
The knowledge of the phase diagram of the Al?CGe?CZn ternary system is of importance in the development of high temperature soldering materials. In this study, the phase diagram of the Al?CGe?CZn ternary system was calculated by the calculation of phase diagrams method using binary thermodynamic parameters included in the COST MP0602 thermodynamic database. Chosen alloys with compositions along two vertical sections with molar ratio Al/Ge?=?3/1 and 1/3 were measured using DTA (differential thermal analysis). The experimentally determined phase transition temperatures from this work and phase equilibria data from literature were compared with calculation results and good mutual agreement was noticed. 相似文献
93.
Dijana Mosi? Dragan S. Djordjevi? 《Applied mathematics and computation》2012,218(9):5383-5390
We present characterizations of weighted-EP elements in C∗-algebras using different kinds of factorizations. 相似文献
94.
In 1983, the second author [D. Maru?i?, Ars Combinatoria 16B (1983), 297–302] asked for which positive integers n there exists a non‐Cayley vertex‐transitive graph on n vertices. (The term non‐Cayley numbers has later been given to such integers.) Motivated by this problem, Feng [Discrete Math 248 (2002), 265–269] asked to determine the smallest valency ?(n) among valencies of non‐Cayley vertex‐transitive graphs of order n. As cycles are clearly Cayley graphs, ?(n)?3 for any non‐Cayley number n. In this paper a goal is set to determine those non‐Cayley numbers n for which ?(n) = 3, and among the latter to determine those for which the generalized Petersen graphs are the only non‐Cayley vertex‐transitive graphs of order n. It is known that for a prime p every vertex‐transitive graph of order p, p2 or p3 is a Cayley graph, and that, with the exception of the Coxeter graph, every cubic non‐Cayley vertex‐transitive graph of order 2p, 4p or 2p2 is a generalized Petersen graph. In this paper the next natural step is taken by proving that every cubic non‐Cayley vertex‐transitive graph of order 4p2, p>7 a prime, is a generalized Petersen graph. In addition, cubic non‐Cayley vertex‐transitive graphs of order 2pk, where p>7 is a prime and k?p, are characterized. © 2011 Wiley Periodicals, Inc. J Graph Theory 69: 77–95, 2012 相似文献
95.
This paper proposes two optimization models for the periodic inspection of a system with “hard-type” and “soft-type” components. Given that the failures of hard-type components are self-announcing, the component is instantly repaired or replaced, but the failures of soft-type components can only be detected at inspections. A system can operate with a soft failure, but its performance may be reduced. Although a system may be periodically inspected, a hard failure creates an opportunity for additional inspection (opportunistic inspection) of all soft-type components. Two optimization models are discussed in the paper. In the first, soft-type components undergo both periodic and opportunistic inspections to detect possible failures. In the second, hard-type components undergo periodic inspections and are preventively replaced depending on their condition at inspection. Soft-type and hard-type components are either minimally repaired or replaced when they fail. Minimal repair or replacement depends on the state of a component at failure; this, in turn, depends on its age. The paper formulates objective functions for the two models and derives recursive equations for their required expected values. It develops a simulation algorithm to calculate these expected values for a complex model. Several examples are used to illustrate the models and the calculations. The data used in the examples are adapted from a real case study of a hospital’s maintenance data for a general infusion pump. 相似文献
96.
97.
Conder Marston D. E. Hujdurović Ademir Kutnar Klavdija Marušič Dragan 《Journal of Algebraic Combinatorics》2021,53(3):881-895
Journal of Algebraic Combinatorics - Properties of symmetric cubic graphs are described via their rigid cells, which are maximal connected subgraphs fixed pointwise by some involutory automorphism... 相似文献
98.
99.
100.
Conclusions The racemic form of the AI component of the red San Jose scale pheromone and its analog were synthesized on the basis of available citronellol and geraniol derivatives.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1143–1146, May, 1989. 相似文献