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1.
Guang Pu Xue Yu Guang Pu Fen Xi ; 35(6): 1516-9, 2015 Jun.
Artigo em Zh | MEDLINE | ID: mdl-26601358

RESUMO

In this paper, first time as our knowledge, we describe the development and performance evaluation of a 4.4 µm external cavity quantum cascade laser based laser heterodyne radiometer. Laser heterodyne spectroscopy is a high sensitive laser spectroscopy technique which offers the potential to develop a compact ground or satellite based radiometer for Earth observation and astronomy. An external cavity quantum cascade laser operating at 4. 4 µm, with output power up to 180 mW and narrow line width was used as a local oscillation. The external cavity quantum cascade laser offers wide spectral tuning range, it is tunable from 4.38 to 4.52 µm with model hop free and can be used for simultaneous detections of CO2, CO and N2 O. A blackbody was used as a signal radiation source. Development and fundamental theory of Laser heterodyne spectroscopy was described. The performance of the developed Laser heterodyne radiometer was evaluated by measuring of CO2 spectral at different pressures. Analyses results showed that a signal-to-noise ratio of 86 was achieved which was less than the theoretical value of 287. The spectral resolution of the developed Laser heterodyne spectroscopy is about 0.007 8 cm(-1) which could meet the requirement of high resolution spectroscopy measurement in the case of Doppler linewidth. The experiment showed that middle Infrared laser heterodyne spectroscopy system had high signal-to-noise ratio and spectral resolution, and had broad application prospect in high precision measurement of atmospheric greenhouse gas concentration and vertical profile.

2.
Angew Chem Int Ed Engl ; 54(25): 7381-5, 2015 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-25950511

RESUMO

A chiral secondary amine phosphoramide was developed and identified as a powerful catalyst for the Mukaiyama-Michael addition of fluorinated enol silyl ethers to tetrasubstituted olefins. The resulting products are obtained with high enantioselectivities and contain a quaternary carbon stereocenter bearing either a difluoroalkyl or monofluoroalkyl group.

3.
J Am Chem Soc ; 135(30): 10994-7, 2013 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-23855917

RESUMO

We report a highly enantioselective Cu(I)-catalyzed azide-alkyne cycloaddition via asymmetric desymmetrization of oxindole-based 1,6-heptadiynes, which furnishes quaternary oxindoles bearing a 1,2,3-triazole-containing moiety with 84-98% ee.

4.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 2): m118, 2012 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-22346806

RESUMO

In the title compound, [Fe(4)(C(6)H(12)N(2)S(4))(C(18)H(15)P)(2)(CO)(10)], the unit cell contains one mol-ecule, which exhibits a crystallographically imposed center of symmetry. The independent Fe(2)S(2) fragment [Fe-Fe = 2.527 (1) Å] is in a butterfly conformation, and each Fe atom displays a pseudo-square-pyramidal coordination geometry. The phosphane group occupies an apical position [Fe-P = 2.2670 (14) Å]. In the crystal, weak inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into chains along [110].

5.
Chem Commun (Camb) ; 51(90): 16255-8, 2015 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-26399606

RESUMO

We report the first example of the highly enantioselective synthesis of structurally diverse chiral dithioketals via asymmetric sulfenylation of various types of S-based nucleophiles, catalyzed by a cheap cinchona alkaloid derivative, dihydroquinine.


Assuntos
Quinidina/análogos & derivados , Ácidos Sulfínicos/química , Tolueno/análogos & derivados , Catálise , Estrutura Molecular , Quinidina/química , Tolueno/síntese química , Tolueno/química
6.
Huan Jing Ke Xue ; 36(4): 1317-25, 2015 Apr.
Artigo em Zh | MEDLINE | ID: mdl-26164906

RESUMO

Based on the investigation of phytoplankton and water body nutrient concentration in the ecology-monitoring area of Changli in summer from 2005 to 2013, the phytoplankton community structure was analyzed. The result showed that in recent 9 years, 3 phyla including 23 families, 39 genera and 105 species of phytoplankton were identified, in which 85.7% were diatoms and 13.3% were dinoflagellate. Only one species was found belonging to golden algae. There was great difference in dominant species among different years. According to the value of dominance, there were Coscinodiscus radiatus, Coscinodiscus debilis, Rhizosolenia styliformis, Cerataulina bergoni, Coscinodiscus wailesii, Thalassiosira sp., Ceratium tripos, Chaetoceros lorenzianus, Skeletonema costatum. The cell abundance was decreased yearly. The Shannon-Wiener index of phytoplankton community ranged from 0.015 to 3.889, and the evenness index ranged from 0.009 to 1, which showed little yearly change. And phytoplankton species were unevenly distributed among the 19 sites, there were relatively low amount of dominant species, but the dominance was relatively high. Canonical Correspondence Analysis (CCA) results of the phytoplankton community and its environmental factors showed that the environmental factors influencing the change of phytoplankton community structure in summer included water temperature, nutrients (TP, TN and NO3(-) -N, NH4(+)-N) and salinity, and the structural change was the result of the interactions of different environmental factors.


Assuntos
Fitoplâncton , Estações do Ano , China , Chrysophyta , Diatomáceas , Dinoflagellida , Ecossistema , Dinâmica Populacional
7.
Chem Commun (Camb) ; 50(96): 15179-82, 2014 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-25335923

RESUMO

A new cinchona alkaloid derived bifunctional tertiary amine-phosphoramide is identified as a highly enantioselective catalyst for Michael addition of both unprotected 3-arylthio- and 3-alkylthiooxindoles to nitroolefins. The phosphoramide moiety of plays an indispensable role in this reaction.


Assuntos
Alcenos/química , Alcaloides de Cinchona/química , Indóis/química , Fosforamidas/química , Compostos de Sulfidrila/química , Catálise , Estereoisomerismo
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