全文获取类型
收费全文 | 56篇 |
免费 | 0篇 |
专业分类
化学 | 43篇 |
晶体学 | 1篇 |
力学 | 3篇 |
数学 | 2篇 |
物理学 | 7篇 |
出版年
2021年 | 1篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2014年 | 3篇 |
2013年 | 3篇 |
2012年 | 1篇 |
2011年 | 5篇 |
2010年 | 2篇 |
2009年 | 2篇 |
2008年 | 2篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 1篇 |
1999年 | 1篇 |
1995年 | 3篇 |
1992年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有56条查询结果,搜索用时 31 毫秒
1.
We present a new method for homocysteine quantitation in human plasma based on in-capillary reaction of homocysteine with 2,2′-dipyridyl disulfide. Homocysteine is in this so-called thiol-exchange reaction quantitatively transformed in mixed disulfide concomitantly with formation of an equimolar amount of 2-thiopyridone that is further separated by micellar electrokinetic chromatography and determined specifically at 343 nm. The concentration of homocysteine is thus estimated indirectly from the result of 2-thiopyridone determination. The linear detection range for concentration versus peak area for the assay was from 0.03–3 mM (correlation coefficient 0.994) with a detection limit of 6 μM and a limit of quantitation 20 μM. The inter-day reproducibility of the peak area and the migration time were 1.37% and 0.05%, respectively. The method is simple, relatively rapid and can be easily automated. Moreover the common capillary electrophoresis apparatus with a UV detector can be used to distinguish between normal and pathological hyperhomocysteinemia plasma samples. 相似文献
2.
Kakiuchi F Tsuchiya K Matsumoto M Mizushima E Chatani N 《Journal of the American Chemical Society》2004,126(40):12792-12793
Ruthenium-catalyzed silylation of sp3 C-H bonds at a benzylic position with hydrosilanes gave benzylsilanes. For this silylation reaction, Ru3(CO)12 complex showed high catalytic activity. This silylation proceeded at the methyl C-H bond selectively. For this silylation reaction, pyridyl and pyrazolyl groups, and the imino group in hydrazones, can function as a directing group. Several hydrosilanes involving triethyl-, dimethylphenyl-, tert-butyldimethyl-, and triphenylsilanes can be used as a silylating reagent. Coordination of an sp2 nitrogen atom to the ruthenium complex is important for achieving this silylation reaction. 相似文献
3.
Masatoshi Hasegawa Daiki Hirano Mari Fujii Misako Haga Eiichiro Takezawa Shinya Yamaguchi Atsushi Ishikawa Takashi Kagayama 《Journal of polymer science. Part A, Polymer chemistry》2013,51(3):575-592
This work presents novel colorless polyimides (PIs) derived from 1R,2S,4S,5R‐cyclohexanetetracarboxylic dianhydride (H″‐PMDA). Isomer effects were also discussed by comparing with PI systems derived from conventional hydrogenated pyromellitic dianhydride, that is, 1S,2R,4S,5R‐cyclohexanetetracarboxylic dianhydride (H‐PMDA). H″‐PMDA was much more reactive with various diamines than H‐PMDA, and the former led to PI precursors with much higher molecular weights. The results can be explained from the quite different steric structures of these isomers. The thermally imidized H″‐PMDA‐based films were colorless regardless of diamines because of inhibited charge‐transfer interaction. In particular, the H″‐PMDA/4,4′‐oxydianiline system simultaneously achieved a very high Tg exceeding 300 °C, high toughness (elongation at break > 70%), and good solution processability. In contrast, the H‐PMDA‐based counterparts were essentially insoluble. The outstanding solubility of the former probably results from disturbed chain stacking by its nonplanar steric structure. An advantage of chemical imidization process is also proposed. In some cases, a copolymerization approach with an aromatic tetracarboxylic dianhydride was effective to improve the thermal expansion property. The results suggest that the H″‐PMDA‐based PI systems can be promising candidates for novel high‐temperature plastic substrate materials in electronic paper displays. A potential application as optical compensation film materials in liquid crystal displays (LCD) is also proposed in this work. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
4.
Sugimoto T Bamba T Izumi Y Nomura H Shiina T Fukusaki E 《Journal of separation science》2011,34(24):3587-3596
This study sought to develop techniques for LC/MS-based metabolomics and to verify that an MS/MS spectral tag (MS2T) could be used in practical secondary metabolite profiling. The retention time (RT), precursor ions, and fragment ions generated by nozzle-skimmer fragmentation were determined using ultra-performance liquid chromatography/time-of-flight mass spectrometry (UPLC/TOF-MS) and compared with the MS2T. A standard mix was analyzed with UPLC/TOF-MS under the same conditions as were used to construct the MS2T. The difference in RT for the standards was less than 0.15 min and the average RSD was about 2.8%, suggesting that the analysis was highly repeatable. Both precursor ions and fragment ions were observed when the cone voltage was 75 V. Experimental data and fragmentation pattern in the MS2T annotation list were highly similar. Wild-type and cas-1 mutant Arabidopsis thaliana samples treated with an elicitor were analyzed using UPLC/TOF-MS. Sixty-five peaks were successfully annotated. Fragment ions were observed with nozzle-skimmer fragmentation in 50 of 65 (77%) peaks. The reliability of annotation may have increased as a result of fragment ions. Results of multivariate analysis suggested that cas-1 was related to induction of the biosynthesis of these flavonoids. The devised method facilitated practical secondary metabolite profiling. 相似文献
5.
Lee JW Yamamoto T Uchikata T Matsubara A Fukusaki E Bamba T 《Journal of separation science》2011,34(24):3553-3560
We established a high-throughput and high-resolution analytical method based on supercritical fluid chromatography (SFC) coupled with mass spectrometry (MS) for the simultaneous profiling of diverse polar lipids in a mixture. Trimethylsilyl (TMS) derivatization was used for the analysis of ten polar lipids: phosphatidylglycerol (PG), phosphatidic acid (PA), phosphatidylinositol (PI), lysophosphatidylcholine (LPC), lysophosphatidylethanolamine (LPE), lysophosphatidylglycerol (LPG), lysophosphatidic acid (LPA), lysophosphatidylinositol (LPI), sphingomyeline (SM), and sphingosine-1-phosphate (S1P). Using the developed method, the peak tailings of PA, PI, LPA, LPI, and S1P improved, and the limit of detection of PG, PI, LPA, LPI, and S1P was enhanced by 12-, 40-, 510-, 39-, and 1490-fold, respectively. Next, in the analysis of sheep plasma, 20 minor species of PI, LPC, LPE, and SM, and 7 molecular species of LPA, LPI, and S1P were additionally analyzed. The relative ratio of the molecular species in each polar lipid was also found by quantification. Finally, the simultaneous and detail profiling of ten polar lipids was successfully performed by SFC/MS applying TMS derivatization. This developed method is particularly applicable to metabolomics, especially for targeting polar lipids. 相似文献
6.
Kouichi Tsuji Tetsuya Emoto Yosuke Nishida Eiichiro Tamaki Yoshikuni Kikutani Akihide Hibara Takehiko Kitamori 《Analytical sciences》2005,21(7):799-803
Grazing-exit x-ray fluorescence (GE-XRF) and micro x-ray fluorescence (micro-XRF) methods were applied to chemical microchips as a detection method. Since an energy-dispersive x-ray detector was used, the simultaneous detection of multiple elements was possible. An analyzing region was especially designed on the microchip so that a sample solution could be dried and concentrated in a suitable area corresponding to the size of the primary x-ray beam. Finally, it was confirmed that both analytical methods could be combined well for use with a microchip. In GE-XRF, the background intensity in the XRF spectrum was reduced at grazing-exit angles. In addition, a good relationship between the x-ray fluorescence intensities and the concentrations of standard solutions that were introduced into the microchip was obtained. This indicates that the GE-XRF method is feasible for trace elemental analysis in chemical microchip systems. In micro-XRF, an attempt was made to concentrate and dry the analyte within a small analyzing region. The preliminary results indicated that the micro-XRF method could be applied for the analysis of microchips. 相似文献
7.
On the basis of fuzzy sets theory, we propose a method for structuring hierarchy for the several complex problems, and call it Fuzzy Structural Modeling (FSM) method. An important requirement for structural modeling of complex systems is that the necessary data is acquired and organized into a form such that a structural model can be developed. The main purpose of this method is to describe and illustrate a formal procedure for constructing the graphic presentation of the hierarchical arrangement given the necessary information concerning the relation of each element to each other element. The procedure permits an automatic development of the graphic structure that portrays the hierarchy. 相似文献
8.
The addition of 1,10-phenanthroline improves both the extraction and the spectrophotometric sensitivity of the determination of cadmium with diphenylcarbazone. Slope analysis suggests the formation of a 1:2:2 extracted species. The molar absorptivity is 9.4 × 104 l cm-1 mol-1 at 536 nm and extraction is maximal at pH 8.2–9.8. Extraction is rapid and absorbances remain constant at room temperature for 48 h. Various divalent metal ions interfere. 相似文献
9.
Eiichiro Takahagi 《Fuzzy Optimization and Decision Making》2008,7(3):219-232
We propose an identification method of fuzzy measures by diamond pairwise comparisons. Right and left side of the diamond
means ordinal weights’ comparison and up and down means interaction degrees. From the comparisons, we estimate a hierarchy
diagram with interaction degrees and weights of evaluation items using the agglomerative hierarchical clustering method. From
the diagram, to identify the fuzzy measure, conversion method is proposed. 相似文献
10.
Complexing ability of natural organic ligands in seawater was determined by an approach based on coordination chemistry, i.e., thermodynamic calculations of the conditional stability constants of remarkably stable copper(II) complexes of natural ligands, which were maintained against the ligand-exchange reaction with a large excess of ethylenediaminetetraacetic acid. There exist strong ligands with the conditional stability constant of log K’CuL > 14 at pH 5.71 and 4°?C ubiquitously in non-living dissolved organic matter, concentrated from both coastal and oceanic regimes. This type of ligand was detected at most depths from surface to 1,000 m in the oceanic regimes. The same appraoch was applied to a sample of marine organism (phytoplankton) and the strong ligand class was found out in phytoplankton. It is suggested that phytoplankton may be one of potential sources for the strong ligand. 相似文献