全文获取类型
收费全文 | 1180篇 |
免费 | 23篇 |
国内免费 | 4篇 |
专业分类
化学 | 850篇 |
晶体学 | 2篇 |
力学 | 23篇 |
数学 | 195篇 |
物理学 | 137篇 |
出版年
2020年 | 9篇 |
2019年 | 10篇 |
2018年 | 8篇 |
2017年 | 11篇 |
2016年 | 17篇 |
2015年 | 12篇 |
2014年 | 18篇 |
2013年 | 59篇 |
2012年 | 47篇 |
2011年 | 32篇 |
2010年 | 35篇 |
2009年 | 27篇 |
2008年 | 54篇 |
2007年 | 54篇 |
2006年 | 42篇 |
2005年 | 47篇 |
2004年 | 53篇 |
2003年 | 42篇 |
2002年 | 22篇 |
2001年 | 9篇 |
1997年 | 15篇 |
1996年 | 10篇 |
1995年 | 14篇 |
1994年 | 11篇 |
1993年 | 11篇 |
1992年 | 15篇 |
1988年 | 8篇 |
1987年 | 11篇 |
1985年 | 24篇 |
1984年 | 23篇 |
1983年 | 15篇 |
1982年 | 21篇 |
1981年 | 24篇 |
1980年 | 19篇 |
1979年 | 23篇 |
1978年 | 30篇 |
1977年 | 15篇 |
1976年 | 24篇 |
1975年 | 26篇 |
1974年 | 25篇 |
1973年 | 23篇 |
1972年 | 10篇 |
1971年 | 7篇 |
1970年 | 12篇 |
1969年 | 10篇 |
1968年 | 11篇 |
1967年 | 7篇 |
1960年 | 8篇 |
1959年 | 9篇 |
1954年 | 8篇 |
排序方式: 共有1207条查询结果,搜索用时 16 毫秒
991.
Abby R. O'Connor Maurice Brookhart 《Journal of polymer science. Part A, Polymer chemistry》2010,48(9):1901-1912
Polymerizations of 1,3‐dienes using in situ generated catalyst [(2‐methallyl)Ni][B(ArF)4], 6 , (ArF = 3,5‐bis(trifluoromethyl)phenyl) as well as [(2‐methallyl)Ni(mes)][B(ArF)4], 14 , (mes = mesitylene) are reported. Highly sensitive complex 6 polymerizes butadiene (BD) at –30 °C to yield polybutadiene with a Mn of ca. 10 K and 94% cis‐1,4‐enchainment while less reactive isoprene (IP) was polymerized at 23 °C to yield polyisoprene with Mn ca. 7 K. Complex 6 was also shown to polymerize a functionalized diene, 2,3‐bis(4‐trifluoroethoxy‐4‐oxobutyl)‐1,3‐BD, to polymer with Mn = 113 K. The stable and readily isolated arene complex 14 initiates BD and IP polymerizations at somewhat higher temperatures relative to 6 and delivers polymers with higher molecular weights. Complex [(allyl)Ni(mes)][B(ArF)4], 13 , catalyzes polymerization of styrene to yield polystyrene with high conversion, Mn's = ca. 6 K and MWD = 2. The π‐benzyl complex [(η3‐1‐methylbenzyl)Ni(mes)] [B(ArF)4], 19 , was detected as an intermediate following chain transfer by in situ NMR studies. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1901–1912, 2010 相似文献
992.
993.
994.
995.
A. Cousin O. Forni S. Maurice O. Gasnault C. Fabre V. Sautter R.C. Wiens J. Mazoyer 《Spectrochimica Acta Part B: Atomic Spectroscopy》2011,66(11-12):805-814
The NASA Mars Science Laboratory rover will carry the first Laser Induced Breakdown Spectroscopy experiment in space: ChemCam. We have developed a laboratory model which mimics ChemCam's main characteristics. We used a set of target samples relevant to Mars geochemistry, and we recorded individual spectra. We propose a data reduction scheme for Laser Induced Breakdown Spectroscopy data incorporating de-noising, continuum removal, and peak fitting. Known effects of the Martian atmosphere are confirmed with our experiment: better Signal-to-Noise Ratio on Mars compared to Earth, narrower peak width, and essentially no self-absorption. The wavelength shift of emission lines from air to Mars pressure is discussed. The National Institute of Standards and Technology vacuum database is used for wavelength calibration and to identify the elemental lines. Our Martian database contains 1336 lines for 32 elements: H, Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, K, Ar, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Rb, Sr, Cs, Ba, and Pb. It is a subset of the National Institute of Standards and Technology database to be used for Martian geochemistry. Finally, synthetic spectra can be built from the Martian database. Correlation calculations help to distinguish between elements in case of uncertainty. This work is used to create tools and support data for the interpretation of ChemCam results. 相似文献
996.
997.
998.
Maurice Fréchet 《Acta Mathematica》1926,47(1-2):25-52
999.
Maurice Lecat 《Mathematische Zeitschrift》1922,15(1):291-308
Sans résumé 相似文献
1000.
The imprints left by quantum mechanics in classical (Hamiltonian) mechanics are much more numerous than is usually believed. We show that the Schrödinger equation for a nonrelativistic spinless particle is a classical equation which is equivalent to Hamilton’s equations. Our discussion is quite general, and incorporates time-dependent systems. This gives us the opportunity of discussing the group of Hamiltonian canonical transformations which is a non-linear variant of the usual symplectic group. 相似文献