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Detection of Claisen Rearrangement Occurring in Allyl Phenyl Ether by in situ GC/MS

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Chinese Chemical Letters 1998年第4期9卷 381-384页

作者： jian jun zhai Wei YING Fan Zhi ZHA0 Yao Zu CHEN(National Laboratory of Applied Organic Chemistry at Lanzhou University, Lanzhou 730000) Natl. Lab. of Appl. Organ. Chemistry Lanzhou University Lanzhou 730000 China

We report here a new strategy for revealing the Claisen rearrangement of allyl phenyl ether occurring in the gas phase by in situ GC/MS technique. The Claisen rearrangement has been observed when allyl phenyl ether passed through the capillary column at certain temperatures. The relative proportion of rearrangement products is dependent on the temperature of the capillary column and the substituents on the phenyl ring.

关键词： in situ GC/MS allyl phenyl ether Claisen rearrangement

Study of primordial deuterium abundance in Big Bang nucleosynthesis

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Nuclear Science and Techniques 2024年第3期35卷 208-215页

作者： Zhi-Lin Shen jian-jun He Key Laboratory of Beam Technology of Ministry of Education College of Nuclear Science and TechnologyBeijing Normal UniversityBeijing 100875China Institute of Radiation Technology Beijing Academy of Science and TechnologyBeijing 100875China

Big Bang nucleosynthesis(BBN)theory predicts the primordial abundances of the light elements^(2) H(referred to as deuterium,or D for short),^(3)He,^(4)He,and^(7) Li produced in the early *** these,deuterium,the first nuclide produced by BBN,is a key primordial material for subsequent *** date,the uncertainty in predicted deuterium abundance(D/H)remains larger than the observational *** this study,the Monte Carlo simulation code PRIMAT was used to investigate the sensitivity of 11 important BBN reactions to deuterium *** found that the reaction rate uncertainties of the four reactions d(d,n)^(3)He,d(d,p)t,d(p,γ)^(3)He,and p(n,γ)d had the largest influence on the calculated D/H ***,the calculated D/H uncertainty cannot reach observational precision even with the recent LUNA precise d(p,γ)^(3) He *** the nuclear physics aspect,there is still room to largely reduce the reaction-rate uncertainties;hence,further measurements of the important reactions involved in BBN are still necessary.A photodisintegration experiment will be conducted at the Shanghai Laser Electron Gamma Source Facility to precisely study the deuterium production reaction of p(n,γ)d.

关键词： Big Bang nucleosynthesis Abundance of deuterium Reaction cross section Reaction rate Monte Carlo method

Liquid-phase epitaxial layer by layer brushing fabrication of metalorganic frameworks films

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Nano Research 2024年第6期17卷 5698-5704页

作者： Li-Mei Chang Rui zhai Zhi-Zhou Ma jian-Dong Huang Zhi-Gang Gu jian Zhang College of Chemistry Fuzhou UniversityFuzhou 350108China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China University of Chinese Academy of Sciences Beijing 100049China

Development of metal-organic framework(MOF)films is of great importance to expand their ***,we report a facile and universal method of liquid-phase epitaxial(LPE)layer by layer(LBL)brushing approach for fabricating MOF films on various substrates in a high-throughput *** MOF films preparation method offers a great prospective to cost-effectively construct films with short preparation time and little reagent ***,this LBL brushing approach has been implemented successfully to assemble various MOF films,including HKUST-1,zeolitic imidazolate framework-8(ZIF-8),Cu(bdc),and Cu_(2)(L)_(2)P(L=bdc,ndc,and cam;P=dabco and bipy).Afterwards,the classic MOF HKUST-1 and ZIF-8 films were grown on sensor chip electrode and porous fiber support for good volatile organic compounds(VOCs)selective sensing and water purification *** study demonstrates that this LBL brushing preparation method can be employed to synthesize various MOF films with a variety of characteristics to realize their sensing and separation applications.

关键词： metal-organic framework porous materials layer by layer fabrication film

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基于不相关模态振型的修正技术

航空动力学报 2017年第2期32卷 405-415页

作者：翟学王建军翟庆刚北京航空航天大学能源与动力工程学院北京100191 北京航空工程技术研究中心可靠性工程组北京100076

为充分利用试验测量结果,探讨了一种修正技术,不但有效利用试验数据中与有限元模型相关的模态信息,同时也有效利用不相关模态信息,并成功应用于某型现代高推质比涡扇发动机结构中.通过计算,修正后的模型计算值与试验测试值比较接近,误... 详细信息

为充分利用试验测量结果,探讨了一种修正技术,不但有效利用试验数据中与有限元模型相关的模态信息,同时也有效利用不相关模态信息,并成功应用于某型现代高推质比涡扇发动机结构中.通过计算,修正后的模型计算值与试验测试值比较接近,误差接近0,MAC(model assurance criteria)值接近1.研究表明:利用不相关模态振型的模型修正技术能够有效得到准确的修正参数值,且修正后的有限元模型具有很高的计算精度.

关键词：结构动力学模型修正振动模态测量试验数据应用振型相关性目标函数

Environmental benefits and farmers' adoption of winter cover crops in the North China Plain

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Pedosphere 2024年第1期34卷 159-169页

作者： Shufang GUO Yitao ZHANG Limei zhai jian LIU Hongyuan WANG Hongbin LIU State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China Key Laboratory of Nonpoint Source Pollution ControlMinistry of Agriculture and Rural AffairsInstitute of Agricultural Resources and Regional PlanningChinese Academy of Agricultural SciencesBeijing 100081China Institute of Agricultural Environment and Resources Yunnan Academy of Agricultural SciencesKunming 650205China Shandong Yucheng Agro-ecosystem National Observation Research Station Key Laboratory of Ecosystem Network Observation and ModelingInstitute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China The Norwegian Institute of Bioeconomy Research(NIBIO) Akershus 1431Norway

The introduction of cover crops into monoculture systems to improve soil health has been widely adopted worldwide. However, little is known about the environmental risks and application prospects of different cover crops in spring maize(Zea mays L.) monocultures proposed in the North China Plain. A pot experiment was conducted to evaluate the effects of different winter cover crops on subsequent maize yield, soil fertility, and environmental risks of nitrogen(N) loss, and a questionnaire survey was conducted to examine factors influencing farmers' willingness to adopt cover crops in the North China Plain. Based on the same fertilization regime during the maize growing period, four winter cover crop treatments were set up, including bare fallow, hairy vetch(Vicia villosa Roth.), February orchid(Orychophragmus violaceus), and winter oilseed rape(Brassica campestris L.). The results indicated that winter cover crops significantly increased subsequent maize yield and soil organic carbon, total N, and microbial biomass carbon and N compared with the bare fallow *** incorporation of cover crops led to a negligible increase in nitrous oxide(N_(2)O) emissions and had a very limited effect on ammonia(NH_(3)) *** incorporation of February orchid and winter oilseed rape decreased nitrate leaching compared with the hairy vetch treatment in the maize growing *** N losses via N_(2)O and NH_(3) emissions and N leaching accounted for 71%–84% of the N surplus. However, yield increase and environmental benefits were not the main positive factors for farmers to accept cover crops. Financial incentive was rated by 83.9% of farmers as an “extremely important” factor, followed by other costs, when considering winter cover cropping. These results indicate that the environmental benefits depend on the type of cover crop. Maintaining high levels of soil fertility and maize yield, providing sufficient subsidies, and encouraging large-area cultivation of cover crops

关键词： cover crop N leaching NH_(3)emission N_(2)O emission spring maize willingness to accept

Interpretation of Chinese Expert Consensus on the Diagnosis and Management Strategy of Patients with Statin Intolerance: A guiding file for helping to lipid management for Chinese population

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Journal of Geriatric Cardiology 2024年第7期21卷 713-715页

作者： jian-jun LI Cardiometabolic Center National Center for Cardiovascular DiseaseChinese Academy of Medical ScienceFuwai HospitalBeijingChina

It is well-known that elevated low-density lipoprotein cholesterol(LDL-C)is a causal risk factor for atheroscler-otic cardiovascular disease(ASCVD),statins are cornerstone drugs for the cause-based treatment of ASCVD,which has created a new era for ASCVD ***,statin intolerance is not clinically uncommon,which there are several issues with confu-sion and ***,a file named Chinese Expert Consensus on the Diagnosis and Management Strategy of Pa-tients With Statin Intolerance,like a navigator,has recently been published written by a team of experts from the Cardiovascular Metabolic Medicine Professional Committee,Expert Committee of the National Center for Cardiovascular Diseases aiming to en-hance the standardized clinical application of statins and improve the prevention and clinical *** this article,author briefly summarized the key points of above consensus in order to helping to comprehending the content of the consensus sugges-tions.

关键词： Expert Strategy corners

Exhaust hood performance and its improvement technologies in industrial buildings:A literatu rereview

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Building Simulation 2024年第1期17卷 23-40页

作者： Jing Zhang jian Wang jun Gao Weimin Zhang Architectural Engineering Institute Jinhua PolytechnicJinhua 321017China Institute of HVAC Engineering Schoolof Mechanical EngineeringTongji UniversityShanghai 200092China Tongji Architectural Design(Group)Co .LtdShanghai 200092China

The pollutant control performance of exhaust hoods plays a crucial role in the indoor air quality and energy consumption of ventilation systems in industrial *** better understand the impact of local ventilation on the industrial indoor environment,this paper presents a literature review of exhaust hood performance and its improvement *** create an index for evaluating the performance of exhaust hoods,the capture velocity,capture efficiency,flow ratio of pollutant emissions and exhaust airflow and energy consumption are first introduced.A number of factors affecting exhaust hood performance are assessed such as hood type,hood opening size,exhaust rate,installation distance,pollution source emission and environmental *** to structural improvement methods,the use of active airflow is a more effective way to improve the exhaust hood *** most commonly used methods for determining the exhaust rate are the controlled speed method and the flow ratio *** use of an exhaust hood with an appropriate exhaust rate and jet parameters(for an active air-assisted hood)can effectively improve the pollutant control performance and reduce the energy consumption that would be wasted on the redundant exhaust *** more information focused on exhaust hood performance,this work suggests more effective strategies for improving indoor air quality and reducing energy consumption in industrial buildings.

关键词： industrial ventilation exhaust hood capture efficiency exhaust rate performance improvement

Retinal vascular morphological characteristics in diabetic retinopathy: an artificial intelligence study using a transfer learning system to analyze ultra-wide field images

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International Journal of Ophthalmology(English edition) 2024年第6期17卷 1001-1006页

作者： Xin-Yi Deng Hui Liu Zheng-Xi Zhang Han-Xiao Li jun Wang Yi-Qi Chen jian-Bo Mao Ming-zhai Sun Li-jun Shen Center for Rehabilitation Medicine Department of OphthalmologyZhejiang Provincial People’s Hospital(Affiliated People’s HospitalHangzhou Medical College)Hangzhou 310014Zhejiang ProvinceChina Department of Precision Machinery and Instrumentation University of Science and Technology of ChinaHefei 230026Anhui ProvinceChina Department of Retina Eye Hospital of Wenzhou Medical UniversityWenzhou 325027Zhejiang ProvinceChina

AIM:To investigate the morphological characteristics of retinal vessels in patients with different severity of diabetic retinopathy(DR)and in patients with or without diabetic macular edema(DME).METHODS:The 239 eyes of DR patients and 100 eyes of healthy individuals were recruited for the *** severity of DR patients was graded as mild,moderate and severe non-proliferative diabetic retinopathy(NPDR)according to the international clinical diabetic retinopathy(ICDR)disease severity scale classification,and retinal vascular morphology was quantitatively analyzed in ultra-wide field images using RU-net and transfer learning *** presence of DME was determined by optical coherence tomography(OCT),and differences in vascular morphological characteristics were compared between patients with and without ***:Retinal vessel segmentation using RU-net and transfer learning system had an accuracy of 99%and a Dice metric of *** with the healthy group,the DR group had smaller vessel angles(33.68±3.01 vs 37.78±1.60),smaller fractal dimension(Df)values(1.33±0.05 vs 1.41±0.03),less vessel density(1.12±0.44 vs 2.09±0.36)and fewer vascular branches(206.1±88.8 vs 396.5±91.3),all P<*** the severity of DR increased,Df values decreased,P=*** significant difference between the DME and non-DME groups were observed in vascular morphological ***:In this study,an artificial intelligence retinal vessel segmentation system is used with 99%accuracy,thus providing with relatively satisfactory performance in the evaluation of quantitative vascular *** patients have a tendency of vascular occlusion and *** presence of DME does not compromise the integral retinal vascular pattern.

关键词： diabetic retinopathy vascular morphology deep learning ultra-wide field imaging diabetic macular edema

Formation of the [M+NH_4]^+ Ious of Some Mouo-and Di-saccharides in Fast Atom Bombardment Mass Spectrometry

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Chinese Chemical Letters 1997年第10期8卷 879-882页

作者： jian jun zhai Fau Zhi ZHAO Deug Gang HUANG Yao Zu CHEN (State Key Laboratory of Applied Organic Chemistry , Lanzhou University , Lanzhou 730000Department of Chemistry , Zhejiang University , Hangzhou 310027)Jin Skan GUO(Gansu Institute of Plast State Key Lab. of Appl. Organ. Chem. Lanzhou University Lanzhou 730000 China Department of Chemistry Zhejiang University Hangzhou 310027 China Gansu Inst. of Plastics and Leather Lanzhou 730000 China

In positive-ion fast atom bombardment (FAB) mass spectrometry, when mono- and di- saccharides are mixed with an appropriate amount of NH4Cl, a highly abundan peak [M+NH4]+appers in FAB mass spectra . From the adduct ... 详细信息

关键词： Mass Atom Ious of Some Mouo-and Di-saccharides in Fast Atom Bombardment Mass Spectrometry M+NH4 Formation of the NH