全文获取类型
收费全文 | 144篇 |
免费 | 3篇 |
专业分类
化学 | 98篇 |
数学 | 17篇 |
物理学 | 32篇 |
出版年
2022年 | 1篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 1篇 |
2013年 | 9篇 |
2012年 | 4篇 |
2011年 | 4篇 |
2010年 | 6篇 |
2009年 | 2篇 |
2008年 | 8篇 |
2007年 | 3篇 |
2006年 | 10篇 |
2005年 | 4篇 |
2004年 | 3篇 |
2003年 | 7篇 |
2002年 | 9篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1987年 | 1篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 5篇 |
1976年 | 7篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1942年 | 2篇 |
排序方式: 共有147条查询结果,搜索用时 392 毫秒
61.
Kevin Swiss Woo-Baeg Choi Julie Mohan Christopher Barnum Manohar Saindane George Zima Dennis Liotta 《Heteroatom Chemistry》1990,1(2):141-149
When lithium enolates are allowed to react with selenium metal, selenolate (selenide) ions are formed. Alkylation of these selenolate ions produces the corresponding α-alkylselenenyl carbonyl derivatives. These derivatives can then be converted to their unsaturated counterparts using the same type of protocols that are employed with arylselenenyl derivatives. 相似文献
62.
L.F. Liotta A. Macaluso G. Pantaleo A. Longo A. Martorana G. Deganello G. Marcì S. Gialanella 《Journal of Sol-Gel Science and Technology》2003,26(1-3):235-240
Ceria-zirconia mixed oxides of nominal composition Ce0.6Zr0.4O2 were prepared by sol-gel method. The structural and morphological modifications of these materials due to calcination and redox treatments up to 1000°C were studied by X-ray diffraction (XRD) and Rietveld refinements, specific surface area measurements (BET), oxygen storage capacity (OSC), TEM and SEM analyses. The materials maintain high OSC after several hours of treatments at 1000°C in oxidizing and reducing atmosphere, showing good resistance to the thermal ageing. An improvement of the OSC is manifested after repetitive redox cycles, even though textural characterization shows that reduction/oxidation processes induce sintering of the crystallites. 相似文献
63.
An evaluation of two-particle resonances in the complex energy plane is presented. The representation used in the method consists of bound and antibound single-particle states, Gamow resonances and scattering waves on the complex energy plane. Within this representation the structure of halo nuclei is studied. 相似文献
64.
65.
Conditions which must be fulfilled by clusters of nucleons to qualify as elementary modes of excitation are analysed in terms of simple criteria involving experimental binding energies. It is found that the most complex possible mode is the α-like cluster. 相似文献
66.
67.
Guindon Y Ogilvie WW Bordeleau J Cui WL Durkin K Gorys V Juteau H Lemieux R Liotta D Simoneau B Yoakim C 《Journal of the American Chemical Society》2003,125(2):428-436
Johnson-type acetals derived from dimethyl tartrate give, after opening with Me(2)BBr and cuprate displacement, secondary alcohols with high diastereoselectivity (>30:1). The mechanism proposed for the induction of diastereoselectivity is downstream from the ring fission. It implies a direct participation of the Lewis acid as a source of nucleophile and the stereospecific transformation of the resulting bromo acetal through an invertive and temperature-dependent process. The acetals are prepared by reaction of the desired aldehyde with dimethyl tartrate. Removal of the auxiliary is accomplished through SmI(2) reduction or by an addition-elimination protocol using methoxide. 相似文献
68.
Relationship between structure and CO oxidation activity of ceria-supported gold catalysts 总被引:1,自引:0,他引:1
Venezia AM Pantaleo G Longo A Di Carlo G Casaletto MP Liotta FL Deganello G 《The journal of physical chemistry. B》2005,109(7):2821-2827
Gold catalysts supported on cerium oxide were prepared by solvated metal atom dispersion (SMAD), by deposition-precipitation (DP), and by coprecipitation (CP) methods and were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), and X-ray photoelectron spectroscopy (XPS). The catalytic activity was tested in the CO oxidation reaction. The structural and surface analyses evidenced the presence of a modified ceria phase in the case of the DP sample and the presence of pure ceria and gold metal crystallites in the case of the SMAD and CP samples. The DP sample, after a mild treatment in air at 393 K, exhibited only ionic gold, and it was very active below 273 K. By comparing the activities of the different catalysts, it is suggested that the presence of small gold particles, as obtained by the SMAD technique, is not the main requisite for the achievement of the highest CO conversion. The strong interaction between ionic gold and ceria, by enhancing the ceria surface oxygen reducibility, may determine the particularly high activity. 相似文献
69.
70.
Anthony V. Galanti Franic Liotta Brian T. Keen Daniel A. Scole 《Journal of polymer science. Part A, Polymer chemistry》1982,20(1):233-239
Members of a series of N,N′-alkylene bisitaconamic acids were synthesized from the reaction between itaconic anhydride and a homologous group of aliphatic diamines with the general formula H2N (CH2)n NH2, where n = 4–12. Cyclodehydration of the acids in toluene gave the isomeric imides: bisitaconimide, biscitraconimide, and citra-itaconimide. The isomeric imides were isolated, purified, and characterized for each diaminoalkane studied. 相似文献