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161.
Dongjie Yang Xueqing Qiu Yuxia Pang Mingsong Zhou 《Journal of Dispersion Science and Technology》2013,34(9):1296-1303
Five purified calcium lignosulfonate (CL) fractions with different molecular weights were obtained by fractionation using ultrafiltration and dialysis. The influence of molecular weight on their physicochemical properties was investigated by determining the properties of five fractions. TEM and ESEM imaging indicated that CL has a globular structure to form locally regular colloidal assemblies with the diameter of approximately 200 ~ 300 nm. Fraction3 (M w is 7621) with the molecular weight of 5,000–l0,000 has more sulfonic and carboxyl group, so the highest zeta potential (?36 mV) can be charged on the TiO2 particles. With the increase of molecular weight, the hydrophobicity and surface activity of CL in aqueous solution increase, so Fraction5 (M w is 21646) which molecular weight is more than 30000 has the biggest adsorption amount. The adsorption characteristic of CL on solid-water interface have great impact on the dispersive properties of TiO2 particle in aqueous solution and the higher adsorption capacity is helpful to improve the dispersive ability of CL. On the other hand, the surface charge of TiO2 particle absorbing CL is another important factor to the dispersive ability of CL. Furthermore, when the CL concentration in TiO2 suspension is less than 4 mg/mL, Fraction3 has the best dispersive ability because the electrostatic repulsion effect is controlling factor. The dispersive ability of CL increases with the increase of molecular weight when the CL concentration in TiO2 suspension is more than 4 mg/mL, so Fraction5 has the best dispersive ability owing to the steric hindrance effect. 相似文献
162.
Self‐Assembled Platinum Nanoflowers on Polydopamine‐Coated Reduced Graphene Oxide for Methanol Oxidation and Oxygen Reduction Reactions 下载免费PDF全文
The morphology‐ and size‐controlled synthesis of branched Pt nanostructures on graphene is highly favorable for enhancing the electrocatalytic activity and stability of Pt. Herein, a facile approach is developed for the efficient synthesis of well‐dispersed Pt nanoflowers (PtNFs) on the surface of polydopamine (PDA)‐modified reduced graphene oxide (PDRGO), denoted as PtNFs/PDRGO, in high yield. The synthesis was performed by a simple heating treatment of an aqueous solution that contained K2PtCl4 and PDA‐modified graphene oxide (GO) without the need for any additional reducing agent, seed, surfactant, or organic solvent. The coated PDA serves not only as a reducing agent, but also as cross‐linker to anchor and stabilize PtNFs on the PDRGO support. The as‐prepared PtNFs/PDRGO hybrid, with spatially and locally separated PtNFs on PDRGO, exhibits superior electrocatalytic activity and stability toward both methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) in alkaline solutions. 相似文献
163.
New di- and triorganotin(IV) derivatives of tyrosinylphenylalanine (H2Tyr-Phe) with general formulae R2Sn(Tyr-Phe) where R = Me,n-Bu, n-Oct and Ph, and R3′Sn(HTyr-Phe) where R′ = Me and Ph have been synthesized. The bonding and coordination behaviour in these derivatives are discussed on the basis of FT-IR, multinuclear 1H, 13C and 119Sn NMR and 119Sn Mössbauer spectroscopic studies. These investigations suggest that dipeptide in R2Sn(Tyr-Phe) acts as dianionic tridentate coordinating through −C(O)O−, -NH2 and (-CO)N−peptide groups while in case of R′3Sn(HTyr-Phe) the ligand acts as monoanionic bidentate coordinating through -C(O)O− and -NH2, and the polyhedron around tin in R2Sn(Tyr-Phe) and R′3Sn(HTyr-Phe) is a distorted trigonal-bipyramidal. It is further confirmed by the single crystal X-ray structure of Me2Sn(Tyr-Phe) · MeOH which shows two methyl groups and peptide nitrogen (N−peptide) in the equatorial positions, while the two axial positions are occupied by the carboxylic oxygen (O−carboxyl) and the amino nitrogen (Namino) atom from the same ligand molecule. One methanol molecule is also present in the asymmetric unit. 相似文献
164.
Dr. Xueqing Chang Dr. Jun-Xing Zhong Sibo Li Dr. Qin Yao Yuxuan Fang Guo Yang Ying Tan Prof. Qifan Xue Prof. Longbin Qiu Dr. Qingqian Wang Prof. Yong Peng Prof. Wu-Qiang Wu 《Angewandte Chemie (International ed. in English)》2023,62(38):e202309292
The 2D/3D perovskite heterostructures have been widely investigated to enhance the efficiency and stability of perovskite solar cells (PSCs). However, rational manipulation of phase distribution and energy level alignment in such 2D/3D perovskite hybrids are still of great challenge. Herein, we successfully achieved spontaneous phase alignment of 2D/3D perovskite heterostructures by concurrently introducing both 2D perovskite component and organic halide additive. The graded phase distribution of 2D perovskites with different n values and 3D perovskites induced favorable energy band alignment across the perovskite film and boosted the charge transfer at the relevant heterointerfaces. Moreover, the 2D perovskite component also acted as a “band-aid” to simultaneously passivate the defects and release the residual tensile stress of perovskite films. Encouragingly, the blade-coated PSCs based on only ≈2 s in-situ fast annealed 2D/3D perovskite films with favorable energy funnels and toughened heterointerfaces achieved promising efficiencies of 22.5 %, accompanied by extended lifespan. To our knowledge, this is the highest reported efficiency for the PSCs fabricated with energy-saved thermal treatment just within a few seconds, which also outperformed those state-of-the-art annealing-free analogues. Such a two-second-in-situ-annealing technique could save the energy cost by up to 99.6 % during device fabrication, which will grant its low-coast implementation. 相似文献
165.
Shidan Weng Xueqing Fu Yu Gao Tianlei Liu Yi Sun Dongqin Tang 《Molecules (Basel, Switzerland)》2021,26(15)
Freesia hybrida is a group of cultivars in the genus Freesia with a strong floral scent composed of diverse volatile organic compounds (VOCs). In this study, the VOCs of 34 F. hybrida were extracted and analyzed by headspace solid phase microextraction and gas chromatography mass spectrometry (HS-SPME-GC-MS). A total of 164 VOCs whose relative contents were higher than 0.05% were detected. The numbers of VOCs in all germplasms differed between 11 to 38, and the relative contents ranged from 32.39% to 94.28%, in which most germplasms were higher than 80%. Terpenoids, especially monoterpenes, were the crucial type of VOCs in most germplasms, of which linalool and D-limonene were the most frequently occurring. Principal component analysis (PCA) clearly separated samples based on whether linalool was the main component, and hierarchical clustering analysis (HCA) clustered samples into 4 groups according to the preponderant compounds linalool and (E)-β-ocimene. Comparison of parental species and hybrids showed heterosis in three hybrids, and the inherited and novel substances suggested that monoterpene played an important role in F. hybrida floral scent. This study established a foundation for the evaluation of Freesia genetic resources, breeding for the floral aroma and promoting commercial application. 相似文献
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167.
分别以β—环糊精和其衍生物为主体分子,在水溶液中与客体分子甲基橙(MO)形成的包合物作为掺杂剂,通过化学方法合成出具有扇形和放射状形态的聚吡咯微管。利用紫外—可见光谱证明了环糊精包合物的形成,通过透射电子显微镜对聚吡咯微管的形态结构进行了表征。 相似文献
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