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排序方式: 共有192条查询结果,搜索用时 46 毫秒
81.
Dr. Benoit Briou Olinda Gimello Cedric Totee Dr. Taizo Ono Dr. Bruno Ameduri 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(68):16001-16010
The radical polymerization of styrene (St) initiated by a trifluoromethyl radical generated from a perfluorinated highly branched persistent radical (PPFR) is presented with an isolated yield above 70 %. The release of .CF3 radical occurred from a temperature above 85 °C. Deeper 1H and 19F NMR spectroscopies of the resulting fluorinated polystyrenes (CF3-PSts) evidenced the presence of both CF3 end-group of the PSt chain and the trifluoromethylation of the phenyl ring (in meta-position mainly). [PPFR]0/[St]0 initial molar ratios of 3:1, 3:10 and 3:100 led to various molar masses ranging from 1750 to 5400 g mol−1 in 70–86 % yields. MALDI-TOF spectrometry of such CF3-PSts highlighted polymeric distributions which evidenced differences between m/z fragments of 104 and 172 corresponding to styrene and trifluoromethyl styrene units, respectively. Such CF3-PSt polymers were also compared to conventional PSts produced from the radical polymerization of St initiated by a peroxydicarbonate initiator. A mechanism of the polymerization is presented showing the formation of a trifluoromethyl styrene first, followed by its radical (co)polymerization with styrene. The thermal properties (thermal stability and glass transition temperature, Tg) of these polymers were also compared and revealed a much better thermal stability of the CF3-PSt (10 % weight loss at 356–376 °C) and a Tg of around 70 °C. 相似文献
82.
This study presents the first example of continuous-flow reaction conditions for biomimetic reductive amination of fluorinated carbonyl compounds using silica-adsorbed DBU as catalyst for on-column process. This new on-column process features operationally convenient conditions, higher chemical yields and purity of products as compared with traditional in-flask reactions. Furthermore the removal of base-catalyst is not an issue in this process at all, as the catalyst (DBU) remains on the column in the “reaction zone”, the feature which makes the overall process substantially more efficient and inexpensive, in particular, for large-scale synthesis of the target α-perfluoroalkyl amines. 相似文献
83.
The presented results convincingly demonstrate that self-disproportionation of enantiomers via sublimation is substantially more complex phenomenon then was previously believed. We demonstrate that the racemic form of isopropyl 3,3,3-trifluoro-2-hydroxypropanoate (1) sublimed faster regardless of the starting enantiomeric composition of the enantiomerically enriched mixtures studied in the range from 20.8, 36.8, 58.7 to 79.4% ee. This preferential sublimation of the racemic form allowed for, the most possibly simple, preparation of optically pure samples of compound 1. In this work we also suggest some general experimental procedures, which may be easily used to facilitate the interpretation of the data collected in different laboratories. 相似文献
84.
Liao Y Song J Li E Luo Y Shen Y Chen D Cheng Y Xu Z Sugioka K Midorikawa K 《Lab on a chip》2012,12(4):746-749
The creation of complex three-dimensional (3D) microfluidic systems has attracted significant attention from both scientific and applied research communities. However, it is still a formidable challenge to build 3D microfluidic structures with arbitrary configurations using conventional planar lithographic fabrication methods. Here, we demonstrate rapid fabrication of high-aspect-ratio microfluidic channels with various 3D configurations in glass substrates by femtosecond laser direct writing. Based on this approach, we demonstrate a 3D passive microfluidic mixer and characterize its functionalities. This technology will enable rapid construction of complex 3D microfluidic devices for a wide array of lab-on-a-chip applications. 相似文献
85.
K Sakakibara LA Joyce T Mori T Fujisawa SH Shabbir JP Hill EV Anslyn K Ariga 《Angewandte Chemie (International ed. in English)》2012,51(38):9643-9646
Push a host: Mechanical compression was applied to a host monolayer at an interface, which facilitated an indicator displacement assay. The fluorescence resonance energy transfer (FRET) between the host and indicator was switched on by this compression. Addition of D-glucose caused the indicator to be displaced, effectively quenching the FRET process. 相似文献
86.
N-Acylsulfonamide is widely used as a carboxylic acid bioisostere. A rapid and mild acyl sulfonamide preparation methodology from carboxylic acid and arylsulfonyl isocyanate in the presence of amine is described. The preparation of biologically active acylsulfonamide by our methodology is also presented. 相似文献
87.
Tsuneyuki Sato Kazuo Kimura Taizo Sugioka Toshikazu Misaki Takayuki Otsu 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(5):1017-1032
Some electron-accepting compounds such as maleimide (MIm), maleic anhydride (MAn), and tetracyanoquinodimethane were found to show pronounced accelerating effects on vinyl polymerization initiated with metal chelates. The polymerization of methyl methacrylate (MMA) initiated with bis(ethyl acetoacetato)-copper(II) (Cu(eacac)2) and MIm was studied kinetically in benzene. The overall activation energy of the polymerization was calculated to be 11.5 kcal/mol. This value was much lower than that (17.6 kcal/mol) for the polymerization of MMA with Cu(eacac)2 alone. The polymerization rate (Rp) was expressed as Rp =k[MIm]1/2 [Cu(eacac)2]1/2 [MMA] The first-order dependence of Rp on the monomer concentration indicated that the monomer had no participation in the initiation step, in contrast with polymerization in the absence of MIm (where a monomer concentration dependence of 1.4th order was observed). Electronic spectroscopic study revealed that a complex between MIm and Cu(eacac)2 had been formed. The ligand radical, an acetylcarboethoxymethyl radical, was trapped by 2-methyl-2-nitrosopropane in the reactions of Cu(eacac)2 with MIm and with MAn in benzene. From these results the mechanism of the initiation of polymerization is discussed. 相似文献
88.
Motozumi Ando Masaki Hirabatake Hisateru Yasui Shoji Fukushima Nobuyuki Sugioka Tohru Hashida 《Biomedical chromatography : BMC》2020,34(3):e4776
Mitotane is a key drug for the treatment of adrenal cortical carcinoma. Due to its narrow therapeutic window, 14–20 μg/mL, monitoring its concentration is crucially important. In this study, a simplified method for measuring mitotane in plasma using gas chromatography-electron ionization-mass spectrometry (GC-EI-MS) was developed. Through deproteination and liquid–liquid extraction, mitotane and an internal standard (IS) were extracted from plasma samples. GC-EI-MS yielded retention times of 8.2 and 8.7 min, for mitotane and the IS, respectively, with a total run time of 12 min. Selectivity and intra-/inter-batch accuracy and precision analyses provided a lower limit of quantification of 0.25 μg/mL, and a calibration curve between 0.25 and 40 μg/mL had good linearity (coefficient of determination = 0.992). The matrix effect factor and percent recovery of the method had good precision. Additionally, long-term sample stability was observed below 4°C. In a clinical setting, mitotane levels in plasma from an adrenal cortical carcinoma patient were within calibration range. Therefore, this simplified method can be applied to routine therapeutic drug monitoring of mitotane, which may contribute to improved treatment of adrenal cortical carcinoma. 相似文献
89.
K. Obata K. Sugioka K. Midorikawa T. Inamura H. Takai 《Applied Physics A: Materials Science & Processing》2006,82(3):479-483
The deep etching of GaN(0001) thin films epitaxially grown on Al2O3(0001) has been investigated by laser ablation using F2 and KrF excimer lasers. The simultaneous irradiation with F2 and KrF excimer lasers markedly improves etching quality compared with single-KrF excimer laser ablation and provides almost
the same quality as that in the case of single-F2 laser ablation with a high etching rate. Additionally, the present method achieves the deep etching of a GaN film of more
than 5 μm in depth with steep side walls at an angle of 87° by changing the laser incidence angle.
PACS 52.38.Mf; 61.82.Fk; 81.65.Cf 相似文献
90.