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排序方式: 共有52条查询结果,搜索用时 171 毫秒
1.
Wenjun Shan 《Journal of organometallic chemistry》2011,696(8):1687-1690
A new polyethylene glycol (PEG) supported ligand, with the PEG chain attached to the nitrogen of TsDPEN, was synthesized using a very simple procedure. The Ru-catalyzed asymmetric transfer hydrogenation of various aromatic ketones in water was investigated with this chiral ligand. High chemical yields and enantioselectivities were obtained under very mild conditions. In addition, the chiral ligand was easily recycled several times and this catalyst was especially suitable for the preparation of chiral tetrahydronaphthalen-1-ol and 2,3-dihydro-1H-inden-1-ol (up to 98% conversion with 99% ee). The latter product can be used as the key intermediate for the synthesis of neuroprotective and anti-AChE agents Rasagiline and Ladostigil. 相似文献
2.
Bifunctional magnetic-optical Fe3O4/ZnO nanocomposites with different molar ratio were successfully synthesized by a facile two-step strategy. Compared with the other methods, it was found to be mild, inexpensive, green, convenient and efficient. Fe3O4 nanocrystal was used as seed for the deposit and growth of ZnO nanoparticle. A series of the characterizations manifested that the combination of Fe3O4 with ZnO nanoparticles was successful. Photocatalytic activity studies confirmed that as-prepared nanocomposites had excellent photodegradating behavior to Methyl Orange (MO) compared to the pure ZnO nanoparticles. The results showed that the degradation percentage of MO was about 93.6% for 1 h when the amount of catalyst was 0.51 g L−1 and initial concentration of MO was 6 × 10−5 mol L−1 in the pH 7 solution. Moreover, the kinetics of photocatalytic degradation reaction could be expressed by the first-order reaction kinetic model. Furthermore, the Fe3O4/ZnO nanocomposites could be also served as convenient recyclable photocatalysts because of their magnetic properties. 相似文献
3.
Thomas D. Foust Andy Aden Abhijit Dutta Steven Phillips 《Cellulose (London, England)》2009,16(4):547-565
With the world’s focus on rapidly deploying second generation biofuels technologies, there exists today a good deal of interest
in how yields, economics, and environmental impacts of the various conversion processes of lignocellulosic biomass to transportation
fuels compare. Although there is a good deal of information regarding these conversion processes, this information is typically
very difficult to use on a comparison basis because different underlying assumptions, such as feedstock costs, plant size,
co-product credits or assumed state of technology, have been utilized. In this study, a rigorous comparison of different biomass
to transportation fuels conversion processes was performed with standard underlying economic and environmental assumptions
so that exact comparisons can be made. This study looked at promising second-generation conversion processes utilizing biochemical
and thermochemical gasification technologies on both a current and an achievable state of technology in 2012. The fundamental
finding of this study is that although the biochemical and thermochemical processes to ethanol analyzed have their individual
strengths and weaknesses, the two processes have very comparable yields, economics, and environmental impacts. Hence, this
study concludes that based on this analysis there is not a distinct economic or environmental impact difference between biochemical
and thermochemical gasification processes for second generation ethanol production. 相似文献
4.
《Arabian Journal of Chemistry》2022,15(9):104035
In this study, we used the Span 80 to enhance solvent extraction process, and we explored the mechanism. The results indicated different solvents would obtain different oil recovery, and toluene showed the optimal oil recovery, and the n-heptane showed the lowest oil recovery. The complex solvents could improve oil recovery. Toluene could make the heavy oil show the lowest viscosity (89.6 Pa.S), and n-heptane make the heavy oil show the highest viscosity (176.3 Pa.S). Complex solvents could decrease the heavy oil viscosities. The higher C/H was, the higher heavy oil recovery was, and when the asphaltene and resins content increase, the C/H would increase. The C/H showed the highest value (9.09, by toluene) and the lowest value (8.15). In this study, Span 80 could increase heavy oil C/H ratio, decrease heavy oil viscosity. Span 80 could make the sands surface more hydrophilic, and then the solvent loss would decrease. The oil recovery was high after 10 times recycle use. 相似文献
5.
《Journal of Saudi Chemical Society》2022,26(2):101421
N-methylation of amines and imines with formic acid as C1 source by easily prepared Pt NPs as heterogeneous catalyst is reported here. Primary, secondary amines and imines were successfully methylated in good to excellent yields under mild conditions. Both aromatic and aliphatic amines could be applied as substrates. Meanwhile, the heterogeneous Pt NPs were capable to be recylcled and reused for 7 times without significant decrease of reactivity. This protocol provided an indirect utilization pathway of CO2 by using formic acid as C1 source. 相似文献
6.
Sj. van der Wal 《Chromatographia》1986,22(1-6):81-87
Summary It was found experimentally that the potential for routine, rapid high-efficiency separations by alternate column, recycle, reversed-phase chromatography is limited by the increase of capacity factors with pressure. 相似文献
7.
GDC(He SiH4)是为HL-1M装置研制的一种常规壁处理技术。在He辉光等离子体条件下,通过气相中的电子碰撞离解、电离、离子-分子反应和在壁面上的He^ 诱导脱H2过程,在清洁的真空壁表面沉积一层无定形、半透明、致密的氢化硅(α-Si:H)薄膜。氢化硅具有良好的H(D)捕获、H2(D2)释放,能显著地降低再循环系数,有效地控制杂质水平,大大拓宽了HL-1M装置的运行范围,为HL-1M装置的LHCD、ICRH、ECRH、NBI、PI和MBI实验提供了良好的真空壁条件。 相似文献
8.
双膦配体的合成及铑-双膦配体催化剂对混合辛烯氢甲酰化反应的催化行为 总被引:4,自引:0,他引:4
合成了具有不同电子效应的 3种双膦配体 .其给电子性为 Ph2 P(CH2 ) 4 PPh2 >Ph2 P(O) (CH2 ) 4 PPh2 >Ph2 P(O) (CH2 ) 4 P(O) Ph2 .这 3种配体与醋酸铑二聚体配合物构成的催化剂 ,在混合辛烯的均相氢甲酰化反应中表现出的活性和选择性与配体给电子性强弱的次序完全相反 .我们认为 ,具有弱配位性的 [Rh(CH3COO) 2 ]2 Ph2 P-(O) (CH2 ) 4 P(O) Ph2 催化体系 ,因其形成的活性物种的活泼性高 ,有利于惰性的长碳链混合辛烯的活化转化 .对该体系循环使用的结果表明 ,经历 3次循环后 ,催化剂活性逐渐降低 . 相似文献
9.
Christophe Desmarets Alain Walcarius Benoît Champagne Raphaël Schneider 《Tetrahedron》2008,64(2):372-381
Stable Pd(0) nanoparticles were prepared at room temperature in 1,4-dioxane from PdCl2 using N,N′-bis(4-methoxyphenyl)-(1,1′-binaphthyl)-4,4′-diamine (naphthidine) as reducing and stabilizing agent. This procedure resulted in Pd(0) particles possessing an average diameter of ca. 25 nm stabilized against aggregation due to a barrier of the naphthidine di(radical cation) Napht2.2+. These particles were evaluated for their capability to act as catalysts in Suzuki-Miyaura coupling reactions. The Pd(0)/Napht2.2+ provides a general and convenient method to prepare biaryls from aryl bromides or iodides and boronic acids with a broad range of functional groups in 1,4-dioxane at 80 °C and under aerobic conditions. 相似文献
10.