全文获取类型
收费全文 | 349篇 |
免费 | 16篇 |
专业分类
化学 | 260篇 |
晶体学 | 1篇 |
力学 | 11篇 |
数学 | 31篇 |
物理学 | 45篇 |
无线电 | 17篇 |
出版年
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 12篇 |
2020年 | 6篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 4篇 |
2016年 | 12篇 |
2015年 | 13篇 |
2014年 | 8篇 |
2013年 | 18篇 |
2012年 | 21篇 |
2011年 | 16篇 |
2010年 | 9篇 |
2009年 | 8篇 |
2008年 | 22篇 |
2007年 | 16篇 |
2006年 | 17篇 |
2005年 | 17篇 |
2004年 | 5篇 |
2003年 | 14篇 |
2002年 | 11篇 |
2001年 | 10篇 |
2000年 | 13篇 |
1999年 | 11篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 8篇 |
1990年 | 2篇 |
1988年 | 5篇 |
1987年 | 1篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1971年 | 1篇 |
1941年 | 2篇 |
1934年 | 2篇 |
排序方式: 共有365条查询结果,搜索用时 250 毫秒
361.
Study of rapid ionisation for simulation of soft X-ray lasers with the 2D hydro-radiative code ARWEN
F. de Gaufridy P. Velarde D. Portillo E. Oliva C. Garcia M. Cotelo A.G. de la Varga P. Zeitoun S. Kazamias K. Cassou O. Guilbaud 《High Energy Density Physics》2011,7(4):294-302
We present our fast ionisation routine used to study transient soft X-ray lasers with ARWEN, a two-dimensional hydrodynamic code incorporating adaptative mesh refinement (AMR) and radiative transport.We compute global rates between ion stages assuming an effective temperature between singly-excited levels of each ion. A two-step method is used to obtain in a straightforward manner the variation of ion populations over long hydrodynamic time steps. We compare our model with existing theoretical results both stationary and transient, finding that the discrepancies are moderate except for large densities. We simulate an existing Molybdenum Ni-like transient soft X-ray laser with ARWEN. Use of the fast ionisation routine leads to a larger increase in temperature and a larger gain zone than when LTE datatables are used. 相似文献
362.
Ma Dolores Galindo José A. Jurado Manuel García Ma Luisa González de Canales Milagrosa Oliva Francisco López 《International journal of environmental analytical chemistry》2013,93(9):1072-1092
The distribution patterns and the organ-specific accumulation trends of 10 trace metals (iron, manganese, zinc, copper, chromium, nickel, cobalt, lead, cadmium and silver) and 4 major elements (sodium, potassium, calcium and magnesium) in 10 different tissues (heart, muscle, kidney, stomach, intestine, liver, gill, gonads, white skin and dark skin) of a benthic fish species (Solea senegalensis) from a densely populated coastal area affected by anthropogenic activities, the Bay of Cadiz (SW Spain), have been investigated. High variability of metal concentrations among tissues were found for Ca, Fe, Zn, Cu, Pb and Ag. Factor analysis was applied to study this variability. Five principal components were found explaining the 92.95% of the total variance and similarities in behavioural patterns of bioaccumulation were described. They associated Mg, Cr, Ni and Mn to intestine and stomach tissues (PC1), Ag, Cu and Cd to liver (PC2), Zn, K and Co to gonads (PC3), Na, Fe and Pb to gill, heart and kidney tissues (PC4) and Ca, Pb and Mn to gill and dark skin (PC5). The metallic concentration in the sediment and water was also studied. The pollution in this area was found moderate with outstanding values of Zn, Cu and Pb (average values of 139, 50.4 and 75.6?mg?kg?1, respectively) in sediment and dissolved Cu (average value of 2.5?µg?L?1). Metal bioconcentration trends followed the order Zn?>?Cu?>?Cd?>?Pb for dissolved metals in seawater, Cu?>?Zn?>?Cd?>?Pb?≈?Mn?>?Fe?≈?Ni?≈?Co for metals associated to particulate matter and Zn?≈?Cu?>?Cd?>?Mn?>?Co?≈?Fe?>?Ni?≈?Pb?>?Cr for metals in the sediment. Higher values were found for copper in liver, zinc in gonads and lead in gill, showing the relationship between biotic and abiotic environment. In addition, Cd bioconcentration factors were found high in liver and gill showing the sensitivity of sole to this metal even at low concentrations. 相似文献
363.
A. Paul Krapcho David J. Waterhouse Abdelhakim Hammach Roberto Di Domenico Ernesto Menta Ambrogio Oliva 《合成通讯》2013,43(5):781-794
Benzylic zinc reagents add with high regioselectivity to 1-(phenoxycarbonyl) salts of methyl nicotinate to yield methyl-1-(phenoxylcarbonyl)-4-benzyl-1,4-dihydronicotinates. The dihydronicotinates on heating with sulfur in decalin afford methyl 4-benzylnicotinates. 相似文献
364.
Dr. Christian Paul Bold Dr. Daniel Lucena-Agell Dr. Dr. María Ángela Oliva Dr. José Fernando Díaz Prof. Dr. Karl-Heinz Altmann 《Angewandte Chemie (International ed. in English)》2023,62(5):e202212190
We describe the total synthesis of the macrodiolide C(13)/C(13′)-bis(desmethyl)disorazole Z through double inter-/intramolecular Stille cross-coupling of a monomeric vinyl stannane/vinyl iodide precursor to form the macrocycle. The key step in the synthesis of this precursor was a stereoselective aldol reaction of a formal Evans acetate aldol product with crotonaldehyde. As demonstrated by X-ray crystallography, the binding mode of C(13)/C(13′)-bis(desmethyl)disorazole Z to tubulin is virtually identical with that of the natural product disorazole Z. Likewise, C(13)/C(13′)-bis(desmethyl)disorazole Z inhibits tubulin assembly with at least the same potency as disorazole Z and it appears to be a more potent cell growth inhibitor. 相似文献
365.