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471.
472.
采用Li NO3对γ-Al2O3进行改性,制备了以多孔锂铝尖晶石为载体,以Pd为活性组分的PdCl2-CuCl2/Li-Al-O负载型催化剂,并考察了催化剂对CO低压气相合成碳酸二乙酯(DEC)反应的催化性能,探讨了载体Li/Al比、改性浸渍方法、不同改性金属、Pd负载量和反应压力等因素对催化剂催化性能的影响.结果表明,当n(Li)/n(Al)=0.2,压力为0.3 MPa和温度为110℃时,DEC的时空收率可达到418 g/(L.h).用Li NO3对γ-Al2O3改性后的催化剂载体表层具有Li Al5O8尖晶石结构,不同Li/Al比的催化剂载体的晶胞参数、晶胞体积略有不同.采用双金属改性的催化剂载体表面由于结晶度较低不能形成"完全尖晶石结构",其催化活性较低.随着催化剂表面活性组分PdCl2含量的增加,可有效提高产物DEC的时空收率;锂铝尖晶石载体表面的酸性较低,有利于提高目标产物DEC的选择性. 相似文献
473.
尽管叠氮二乙基铝Et2AlN3(DEAA)是一个重要的化合物,但人们对它研究还是很少的。本文通过温度-蒸气压关系研究了纯态DEAA的三聚体和单量体之间的缔合-解离平衡;通过相对分子质量测定、核磁共振氢谱和核磁共振铝谱的测定,研究了在苯和甲苯溶液中DEAA的三聚体和单量体之间的缔合-解离平衡。借助温度-蒸气压曲线分别计算了DEAA三聚体和单量体的气化焓和解离焓;通过相对分子质量测定、核磁共振铝谱测定等方法计算得到了溶液中DEAA三聚体和单量体的解离平衡常数、解离焓和解离熵等热力学数据。 相似文献
474.
A new manganese(II) phosphite, Mn2F2(HPO3)(1), was synthesized with tetraethylene pentamine as structure directing agent under hydrothermal conditions. The as-synthesized product was characterized by single crystal X-ray diffraction, powder X-ray diffraction, infrared(IR), UV-Vis spectrum, thermogravimetric analysis(TGA), inductive coupled plasma-atomic emission spectroscopy(ICP-AES), elemental analyses and magnetic susceptibility measurement. Single crystal X-ray diffraction analysis reveals that compound 1 crystallized in the orthorhombic space group Pnma, with a=0.75667(15) nm, b=1.0247(2) nm, c=0.55432(11) nm, V=0.42980(15) nm3, Z=4. The 3D compact framework of compound 1 was built up by the Mn2O6F4 dimers and HPO3 pseudo-pyramids. Compound 1, a new metal-rich manganese phosphite, shows a high thermal stability limit of 550℃. Magnetic measurement indicates that compound 1 exhibits the global antiferromagnetic interactions with a ferromagnetic transition at 28 K. 相似文献
475.
476.
The synthesis and characterization of diethyl oxomalonate‐, glycerol‐, and nitroglycerin‐functionalized polystyrene (DPS, GPS, and NGPS) from polystyrene (PS) by the chemical‐modification route were explored. DPS was synthesized by the Friedel–Crafts acylation of PS with diethyl oxomalonate in the presence of SnCl4 by a batchwise‐addition process. Proton NMR studies indicate that the acylation was essentially quantitative. IR spectroscopy was additionally used to confirm the transformation. The reduction of DPS was carried out using various reduction agents and reaction conditions. The sodium hydride reduction in tetrahydrofuran resulted in a quantitative conversion to GPS as estimated by 1H NMR spectroscopy. Treatment of GPS with a nitrating mixture of nitric and sulfuric acids results in the formation of NGPS. All the polymers were characterized using gel permeation chromatography, IR, UV, 1H spectroscopic techniques, pyrolysis‐mass spectrometry, and thermogravimetric analysis. This is the first investigation on the syntheses of DPS, GPS, and NGPS. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1203–1215, 2001 相似文献
477.
Dong‐Qi Qin Shu‐Hui Qin Kun‐Yuan Qiu 《Journal of polymer science. Part A, Polymer chemistry》2001,39(19):3464-3473
The living radical polymerization of methyl methacrylate and styrene was successfully carried out with diethyl 2,3‐dicyano‐2,3‐diphenylsuccinate (DCDPS)/ferric tri(diethyldithiocarbamate) as a novel reverse atom transfer radical polymerization initiation system in which DCDPS was a hexa‐substituted ethane‐type thermal iniferter, DC was a diethyldithiocarbamate group, and no additional ligands such as nitrogen‐ or phosphine‐based compounds were required. The bulk polymerization of methyl methacrylate was carried out at 95 °C, and that of styrene was carried out at 120 °C. Poly(methyl methacrylate) and polystyrene (PSt) with high molecular weights and quite narrow molecular weight distributions (as low as 1.09 for PSt) were obtained. 1H NMR spectroscopy revealed the presence of an α‐(carbethoxycyanophenyl)methyl group from the initiator and an ω‐DC group from the catalyst in the obtained polymers. Various chain‐extension reactions under UV light or thermal treatments were successfully conducted to prove the presence and efficient reinitiating of the ω‐DC group. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3464–3473, 2001 相似文献
478.
N‐Fluoroalkanesulfonylphosphoramidates, R1SO2NHP(O)‐(OEt)2, have been prepared by a one‐step reaction of fluoroalkanesulfonyl azides (R1SO2N3) with diethyl phosphite at room temperature. The reaction mechanism was also discussed and a favored mechanism was suggested. 相似文献
479.
Phosphonylation of polysiloxane and cyclosiloxane oligomers is described. Hydrosilylation of vinylbenzyl chloride (VBC) with a poly(methylhydrosiloxane), or its cyclic monomer, followed by phosphonylation with triethyl phosphite leads to the production of stable phosphonosiloxanes that are characterized by Si C and C P bonds. The polymer, which is a liquid with a glass transition temperature of −38.3 °C, is soluble in alcohols and an alcohol and water mixture. The phosphonylated siloxanes dissolve and chelate uranyl nitrate and transition metal salts. The hydrosilylation of VBC yields α and β isomers: Si CH2 CH2 and Si CH(CH3); the ratio between these two depends upon the type of solvent and the reaction conversion. A kinetic study of the hydrosilylation reaction of VBC suggests a second order in respect to the reactants. The reaction rate is dependent upon the catalyst concentration and temperature. Hydrosilylation of vinylbenzyl phosphonate could not be accomplished with the platinum (complex) catalyst; this is attributed to the presence of phosphoryl groups that are strong electron donors. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4043–4053, 1999 相似文献
480.
Shu-Hui Qin Kun-Yuan Qiu Graham Swift David G. Westmoreland Shuguang Wu 《Journal of polymer science. Part A, Polymer chemistry》1999,37(24):4610-4615
The bulk polymerization of methyl methacrylate (MMA) initiated with diethyl 2,3-dicyano-2,3-diphenylsuccinate (DCDPS) was studied. This polymerization showed some “living” characteristics; that is, both the yield and the molecular weight of the resulting polymers increased with reaction time, and the resultant polymer can be extended by adding MMA. The molecular weight distribution of PMMA obtained at high conversion is fairly narrow (Mw/Mn = 1.24≈1.34). It was confirmed that DCDPS can serve as a thermal iniferter for MMA polymerization by a “living” radical mechanism. Furthermore, the PMMA obtained can act as a macroinitiator for radical polymerization of styrene (St) to give a block copolymer. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4610–4615, 1999 相似文献