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231.
Sohaib Akbar Emmanuel Beyou Philippe Chaumont Jérôme Mazzolini Edgar Espinosa Franck D'agosto Christophe Boisson 《Journal of polymer science. Part A, Polymer chemistry》2011,49(4):957-965
Polyethylene (PE), alkoxyamine‐ and thiol‐terminated PEs (PE‐TEMPO and PE‐SH, respectively) can be converted to macroradicals using a peroxide, a thermal cleavage of the alkoxyamine and a hydrogen transfer reaction of the thiol, respectively. The addition of these macroradicals to multiwalled carbon nanotubes (MWCNTs) were compared by performing grafting reactions at 160 °C in 1,3‐dichlorobenzene as solvent. Raman spectroscopy was utilized to follow the introduction of PE on the MWCNTs' surface while thermogravimetric and elemental analysis indicated the extent of this grafting. The grafting ratio was found to be in the range of 19–36 wt %. PE‐functionalized MWCNTs were imaged by transmission electronic microscopy showing a PE layer with various thicknesses covering the surface of nanotubes. It was found that higher levels of grafting were obtained using PE‐2,2,6,6‐tetramethylpiperidinyl‐1‐oxy and PE‐SH rather than a radical grafting reaction in which dicumyl peroxide, PE, and MWCNTs were reacted. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
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234.
本文用自旋捕捉剂亚硝基叔丁烷(MNP)和2,3,5,6-四甲基亚硝基苯与ESR相结合分别研究了N-溴代琥珀酰亚胺(NBS)光解反应产生的自由基,以及NBS与醇、取代芳烃及烷烃进行光解夺氢反应生成的活泼自由基中间体,结果表明:1.在紫外光用下,NBS分子中的N-Br键发生均裂,产生N-中心自由基并为MNP所捕获.2.对于醇及烷烃,NBS光解产生的Br能夺取叔碳原子上的氢,分别形成叔碳自由基HOR和R,并被ND所捕获.3.与烷烃及醇不同的是:Br不仅能夺取烷基取代苯分子中叔碳原子上的氢,而且还能夺取仲碳原子上的氢,分别形成自由基PhCR2及PhCHR. 相似文献
235.
A new and very convenient one-carbon ring contraction method is reported. Pyrolysis of α-substituted cycloalkanones at 600-650 °C under flow conditions produces the ring contracted compounds under loss of carbon monoxide. Substrates varying in ring size and nature of the α-substituent have been investigated. 相似文献
236.
Gerald R. Willey Timothy J. Woodman Michael G. B. Drew 《Journal of organometallic chemistry》1996,510(1-2):213-217
Treatment of CpMoC13(MeCN)2 with SbCl5 in acetonitrile solution provides the solvated cationic series [CpMoCl2(MeCN)3]+, [CpMoCl(MeCN)4]2+ and [CpMo(MeCN)6]3+ as hexachloroantimon(V)ate salts following sequential halide abstraction. Characterization follows from microanalytical and spectroscopic (IR, and 1H NMR) data and, in the case of [CpMoCl(MeCN)4][SbCl6]2 · MeCN, by X-ray crystallographic studies. The structure is disordered but individual cations contain a six coordinated pseudo-octahedral metal geometry in which the cyclopentadienyl ligand (regarded as unidentate) and the chlorine atom occupy axial positions with an equatorial array of four acetonitrile ligands. 相似文献
237.
Branko S. Jursic 《Journal of Molecular Structure》1998,430(1-3):17-22
The activation barrier for the CH4 + H → CH3 + H2 reaction was evaluated with traditional ab initio and Density Functional Theory (DFT) methods. None of the applied ab initio and DFT methods was able to reproduce the experimental activation barrier of 11.0-12.0 kcal/mol. All ab initio methods (HF, MP2, MP3, MP4, QCISD, QCISD(T), G1, G2, and G2MP2) overestimated the activation energy. The best results were obtained with the G2 and G2MP2 ab initio computational approaches. The zero-point corrected energy was 14.4 kcal mol−1. Some of the exchange DFT methods (HFB) computed energies which were similar to the highly accurate ab initio methods, while the B3LYP hybrid DFT methods underestimated the activation barrier by 3 kcal mol−1. Gradient-corrected DFT methods underestimated the barrier even more. The gradient-corrected DFT method that incorporated the PW91 correlational functional even generated a negative reaction barrier. The suitability of some computational methods for accurately predicting the potential energy surface for this hydrogen radical abstraction reaction was discussed. 相似文献
238.
Xiaoqing Lu Lianming Zhao Xiangfeng Chen Qingtao Fu Yan Ma 《Journal of organometallic chemistry》2007,692(17):3796-3803
The gas-phase hydride abstraction of methylamine with Cu+(1S) is theoretically investigated by using density functional theory. Geometries for all the stationary points involved are fully optimized at both the B3LYP/6-311++G(d,p) and B3LYP/6-311++G(3df,2p) levels and the reaction is analyzed in terms of the topology of potential energy surface. Approach of Cu+ towards methylamine could form either “classical” N or “nonclassical” η1-methyl-H attached complex with the former being the global minimum. Both complexes are found to be key intermediates for the hydride abstraction, which could transfer into each other via two parallel routes, i.e., concerted metal movement and stepwise C-H activation-rearrangement. A charge-transfer process is detected for the “nonclassical” complex converting to a precursor species (CuH-NH2CH2+), which accounts for the final products by a nonreactive dissociation. 相似文献
239.
A possible isomeriztion channel from BrONO( bromine nitrite) to BrNO2 (nitryl bromide) is predicted by means of MP2 and QCISD(T) (single-point) methods.The channel is a direct bromine abstraction reaction from BrONO molecule by NO2 in which the forward reaction barrier is 89.30 kJ/mol at final UQCISD(T)/6-311 G(2df)//UMP2/6-311G(d) level of theory with zero-point energies included,The result can explian the available experiments very well. 相似文献
240.
F+CH_3OH碰撞反应机机理和反应势能面 总被引:1,自引:0,他引:1
以MP2(full)/6-311 + +g(d,p)水平上详细研究了氟原子与甲醇抽氢反应的 多通道反应机理,得到了各条通道中涉及的驻点的构型和振动频率及其能量,给出 了两张完整的反应势能面,结果表明,氟原子从C原子上抽氢时有一条明显的最低 能量通道,而从氧原子上抽氢时要涉及多条分支通道和多个驻点构型,给出了各分 支通道势能面示意图,结果表明以形成五元环状过渡态通道为优势通道,计算得到 经途径1生成CH_2OH时反应放热170.62kJ/mol,经分支途径6生成CH_3O自由基时反 应放热119.4 kJ/mol,此结果与实验值一致。 相似文献