检索结果-南通市图书馆

Chinese Science Bulletin 1999年第23期44卷 2130-2136页

作者： renwei li Jinshi Chen Shukun Zhang Chinese Acad Sci Inst Geol Beijing 100029 Peoples R China Chinese Acad Geol Sci Inst Geomech Beijing 100083 Peoples R China

δ13C of dolostones from the Wumishan Formation (1 310-1 207 Ma) in the Ming Tombs area near Beijing ranges from - 1.5 to 1.5‰ (PDB), and generally, the δ18O ranges from - 4 to - 5‰ (PDB). The secular variation of stable carbon isotopic compositions is cyclic. δ13C displays positive shifts from a sequence boundary to 1.5 per mil (PDB), then

关键词： carbon and oxygen isotopes Mesoproterozoic. sea-level change.

Facile synthesis of hierarchical NaX zeolite from natural kaolinite for efficient Knoevenagel condensation

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2024年第1期65卷 75-84页

作者： Wen Xiao Peng Dong Chan Wang Jingdong Xu Tiesen li Haibo Zhu Tinghai Wang renwei Xu Yuanyuan Yue National Engineering Research Center of Chemical Fertilizer Catalyst College of Chemical EngineeringFuzhou UniversityFuzhou 350108China Qingyuan Innovation Laboratory Quanzhou 362801China Sinochem Quanzhou Energy Technology Co. Ltd.Quanzhou 362000China

Zeolite catalysts have found extensive applications in the synthesis of various fine ***,the micropores of zeolites impose diffusion limitations on bulky molecules,greatly reducing the catalytic ***,we explore an economic and environmentally friendly method for synthesizing hierarchical NaX zeolite that exhibits improved catalytic performance in the Knoevenagel condensation reaction for producing the useful fine chemical *** synthesis was achieved via a low-temperature activation of kaolinite and subsequent in-situ transformation strategy without any template or *** characterizations reveal that the synthesized NaX zeolite has both intercrystalline and intra-crystalline mesopores,smaller crystal size,and larger external specific surface area compared to commercial NaX *** mechanism investigations show that the inter-crystalline mesopores are generated by stacking smaller crystals formed from in-situ crystallization of the depolymerized kaolinite,and the intra-crystalline mesopores are inherited from the pores in the depolymerized *** synthesis strategy provides an energy-saving and effective way to construct hierarchical zeolites,which may gain wide applications in fine chemical manufacturing.

关键词： Hierarchical NaX zeolite Template-free synthesis Natural kaolinite Knoevenagel condensation

Preliminary report of coseismic surface rupture(part)of Türkiye's M_(W)7.8 earthquake by remote sensing interpretation

在线全文

学校读者我要写书评

暂无评论

Earthquake Research Advances 2024年第1期4卷 4-13页

作者： Yali Guo Haofeng li Peng liang renwei Xiong Chaozhong Hu Yueren Xu Key Laboratory of Earthquake Prediction Institute of Earthquake ForecastingChina Earthquake AdministrationBeijing100036China

Both M_(W) 7.8 and M_(W) 7.5 earthquakes occurred in southeastern Türkiye on February 6,2023,resulting in numerous buildings collapsing and serious *** the distribution of coseismic surface ruptures and secondary disasters surrounding the epicentral area is important for post-earthquake emergency and disaster ***-resolution Maxar and GF-2 satellite data were used after the events to extract the location of the rupture surrounding the first epicentral *** results show that the length of the interpreted surface rupture zone(part of)is approximately 75 km,with a coseismic sinistral dislocation of 2-3 m near the epicenter;however,this reduced to zero at the tip of the southwest section of the East Anatolia Fault ***,dense soil liquefaction pits were triggered along the rupture *** events are in the western region of the Eurasian Seismic Belt and result from the subduction and collision of the Arabian and African Plates toward the Eurasian *** western region of the Chinese mainland and its adjacent areas are in the eastern section of the Eurasian Seismic Belt,where seismic activity is controlled by the collision of the Indian and Eurasian *** China and Türkiye have independent tectonic histories.

关键词： 2023 Türkiye M_(w)7.8 earthquake Coseismic surface rupture East anatolian fault zone Eurasian seismic zone Remote sensing interpretation

Rhodium-Catalyzed Asymmetric Transfer Hydrogenation of Heterocyclic Diaryl Ketones:Facile Access to Key Intermediate of Baloxavir

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2024年第1期42卷 43-47页

作者： li Wang renwei Xiao Jingyuan Song Long-Sheng Zheng Qiwei Lang Gen-Qiang Chen Xumu Zhang Shenzhen Key Laboratory of Small Molecule Drug Discovery and Synthesis Department of Chemistryand Medi-PingshanSouthern University of Science and TechnologyShenzhenGuangdong 518000China Academy for Advanced Interdisciplinary Studies Southern Universityof Science and TechnologyShenzhenGuangdong 518000China Chemistry and Chemical Engineering Guangdong Laboratory ShantouGuangdong 515031China

Transition metal-catalyzed asymmetric transfer hydrogenation has been proven to be a powerful approach for the synthesis of chiral ***,a highly efficient and enantioselective transfer hydrogenation of dibenzoheptaheterocyclic ketones catalyzed by an arene-tethered TsDPEN-based Rh(ll)catalyst has been successfully developed,and a variety of dibenzoheptaheterocyclic ketones were reduced by a 1/1 mixture of formic acid and DBU(1,8-diazabicyclo[5.4.0]undec-7-ene)with high yields and *** this method,the asymmetric reduction of 7,8-difluorodibenzo[b,e]thiepin-11(6H)-one has been realized,providing the key intermediate of baloxavir marboxil with>99% yield and>99% ee at a substrate/catalyst molar ratio of 1000.

关键词： Asymmetric transfer hydrogenation Baloxavir Chiral alcohol Enantioselectivity Heterocyclic diaryl ketone Rhodium(Ⅱ)

Rb-Sr chronological characteristics of Jurassic granitoid gravels in north margin of Dabie block,Central China

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2001年第13期46卷 1126-1129页

作者： li Zhong li renwei Sun Shu Zhang Wenhua Chinese Acad Sci Inst Geol & Geophys Beijing 100029 Peoples R China

Granitoid gravels are discovered from alluvial fan conglomerates, the base of Jurassic Fenghuangtai Formation (J22), in the north margin of Dabie block and the south part of the Hefei Basin. These granitoid gravels make up 5%-10% of all gravels by volume percent. For the four components, K-feldspar, biotite, amphibole and whole rock divided from two selected granitoid gravel samples, their Rb-Sr isotopes are measured, which gives two formation ages of granitoids: (428±20) Ma and (430±54) Ma, and means that the Early Paleozoic granitoid intrusive rocks once existed in the Dabie Mountain provenances of Jurassic. The granitoids occur in the tectonic setting of post-collision upliftaccording to lithogeochemical discriminant analysis.

关键词： Dabie block Hefei Basin granitoid gravels Rb-Sr isotope chronology depositional provenance.

Sedimentary environment indicators: Benzothiazole and its derivatives

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2001年第5期46卷 412-416页

作者： li Yuan li renwei ZHOU Shixin LUO Binjie Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China Lanzhou Institute of Geology Chinese Academy of SciencesLanzhou 730000China

Benzothiazoles distributional characteristics of crude oils and non-hydrocarbon fractions of source rocks in Mangya depression of the Qaidam Basin, Lunnan oil field in the Tarim Basin, Kelamayi oil field in the Junggar Basin and the Tulufan Basin oil field were analyzed. It was found that the distributions of benzothiazole are remarkable diversity in different sedimentary environmental oils. The swamp crude oils contain high quantity of benzothiazole and relatively high quantity of alkylthio-benzothiazole and 2(3H)-benzothiazolone. But the quantity of the 2,2’-dithiobis-benzothiazole is relatively low. The abundance of benzothiazole and 2,2’-dithiobis-benzothiazole are relatively high insemi-brackish water lacustrine crude oils, but the quantity of alkylthio-benzothiazole and 2(3H)-benzothiazolone are relatively low. The benzothiazoles belong to weak acid and mild base compound, and their stabilization conditions relate to their environmental medium. The nitrogenous bases are in favor of alkalescence

关键词： crude oils source rock non-hydrocarbon fraction benzothiazoles sedimentary environment.

A Natural Deduction System of Temporal Logic

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science and Technology 1988年第3期3卷 173-185页

作者：黎仁蔚 Institute of Software Academia Sinica Beijing

This paper will present a natural deduction system of temporal logic,which includes two collections ofinference rules called “horizontal inference rules” and “vertical inference rules” *** is alsoproved that the system is both sound and complete under an appropriate *** natural andgenerally short,each proof in the system can be represented by a matrix whose entries serve to record theinference process.

关键词： Si A Natural Deduction System of Temporal Logic OA Pro oral

基于承诺方案的去中心化可信众包平台设计与实现

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

应用科学学报 2023年第1期41卷 141-152页

作者：王华建黎人玮周寰阳国贵国防科技大学计算机学院湖南长沙410073

为去除传统众包对第三方中心机构的依赖,同时保障众包任务的公平分配和结果的可信提交,提出了一种基于区块链智能合约的可信众包平台设计方案。首先提出了一种基于承诺的两阶段提交机制,并将其运用至接包者的数据提交过程中,以解决区块... 详细信息

为去除传统众包对第三方中心机构的依赖,同时保障众包任务的公平分配和结果的可信提交,提出了一种基于区块链智能合约的可信众包平台设计方案。首先提出了一种基于承诺的两阶段提交机制,并将其运用至接包者的数据提交过程中,以解决区块链上的数据透明度问题,使接包者之间无法相互窃取数据;其次设计了一种无偏随机选择算法,从分散的接包者池中选择相对独立的接包者,杜绝了接包者之间可能的串谋;最后通过模拟选人实验和以太坊上原型系统的实现,验证了选人算法的随机性和整体方案的可行性。

关键词：区块链众包智能合约任务分配承诺方案

在线全文

学校读者我要写书评

暂无评论

大别山周缘盆地物源研究:新结果及运用

沉积学报 2010年第1期28卷 102-117页

作者：李任伟中国科学院地质与地球物理研究所北京100029

叙述单颗粒碎屑矿物在大别山周缘盆地物源分析中的运用。现代河流沉积与大别山源区的对比研究表明碎屑石榴石、K-白云母和电气石的化学组成可以有效地被用于物源分析。它们在侏罗纪—白垩纪—古近纪沉积中的特征揭示了大别山源区岩石组... 详细信息

叙述单颗粒碎屑矿物在大别山周缘盆地物源分析中的运用。现代河流沉积与大别山源区的对比研究表明碎屑石榴石、K-白云母和电气石的化学组成可以有效地被用于物源分析。它们在侏罗纪—白垩纪—古近纪沉积中的特征揭示了大别山源区岩石组成的复杂性,由扬子大陆深俯冲折返所形成的高压—超高压变质岩在白垩纪—古近纪逐渐向东南缘盆地提供了重要的物源,在侏罗纪时期主要分布在大别山北缘盆地的源区。石炭纪时期大别山北缘盆地中碎屑Cr-尖晶石的化学组成和碎屑锆石U-Pb年龄结构指示源区岩石组成主要为早古生代华北大陆南缘活动大陆边缘的特征;此外,锆石U-Pb年龄指示源区岩石也具有扬子大陆的特征。

关键词：物源分析单颗粒碎屑矿物大别山侏罗纪石炭纪

在线全文

学校读者我要写书评

暂无评论

基于人工神经网络的极地船舶冰阻力预报方法

上海交通大学学报 2024年第2期58卷 156-165页

作者：孙乾洋周利丁仕风刘仁伟丁一江苏科技大学船舶与海洋工程学院江苏镇江212100 上海交通大学船舶海洋与建筑工程学院上海200240

极地船舶冰区航行时,冰阻力的准确预报在保障船舶航行安全方面起着重要作用.近年来,机器学习在船舶方面的应用越来越广泛,其中,人工神经网络(ANN)是机器学习领域中一种常用的方法.本文的重点是设计一个用于预报极地船舶冰阻力的ANN模型... 详细信息

极地船舶冰区航行时,冰阻力的准确预报在保障船舶航行安全方面起着重要作用.近年来,机器学习在船舶方面的应用越来越广泛,其中,人工神经网络(ANN)是机器学习领域中一种常用的方法.本文的重点是设计一个用于预报极地船舶冰阻力的ANN模型.参考传统的经验和半经验公式,选择合适的输入特征参数,通过大量的船舶模型试验数据来训练神经网络,搭建径向基(RBF)神经网络模型,并选用遗传算法(GA)进行模型优化.研究表明,基于7个特征参数输入的遗传算法优化径向基(RBF-GA)神经网络模型具有良好的泛化效果,与模型试验和实船试验数据对比,平均误差在8%左右,具有较高的精度,可作为冰阻力预报工具.

关键词：冰阻力机器学习径向基函数神经网络遗传算法船舶试验