检索结果-南通市图书馆

Materials and technolog. of Chinese jades dating.to the Western Zhou period (1050―771 BCE)

在线全文

学校读者我要写书评

暂无评论

Science China(Technolog.cal Sciences) 2008年第4期51卷 467-480页

作者： Janet g.douglas Department of Conservation and Scientific Research Freer Gallery of Art / Arthur M. Sackler Gallery Smithsonian Institution

Excavated jades dating.to the Western Zhou period (1050―771 BCE) from the Xi’an area in Shaanxi Province, China, and contemporaneous jades in the collections of the Arthur M. Sackler g.llery at the Smithsonian Institution have been studied to learn about the jade and stone materials and how they were worked during.the Western Zhou period. Materials identification was carried out using.a combination of techniques such as Fourier-transform infrared spectroscopy and X-ray diffraction. Tool marks were studied using.stereomicroscopy and examination of mold impressions using.scanning.electron microscopy. All of these objects were pro- duced throug. simple processes involving.solid drilling. riffling. and sharp point abrasion; and no evidence was found for the use of rotary tools for incising.or sawing.

关键词： jade nephrite stone China Western Zhou scanning electron microscopy materials technolog. tool marks

Endocrine correlates of mate choice and promiscuity in females of a socially monog.mous avian mating.system with alternative male reproductive phenotypes

在线全文

学校读者我要写书评

暂无评论

Current Zoolog. 2014年第6期60卷 804-815页

作者： Hubert SCHWABL Willow R. LINDSAY douglas g. BARRON Michael S. WEBSTER School of Biolog.cal Sciences and Center for Reproductive Biolog. Washington State University Pullman WA 99164-4236 USA Department of Department of Biolog.cal and Environmental Sciences Goteborg University Box 463405 30 Goteborg Sweden Department of Psycholog. University of South Florida Tampa FL 33620-7200 USA Department of Neurobiolog. and Behavior and Comell Laboratory for Ornithology Comell University Ithaca NY 14850 USA

While our understanding.of male reproductive strateg.es is informed by extensive investig.tions into endocrine mechanisms, the proximate mechanisms by which females compete for mates and adjust reproduction to social environment remains enig.atic. We set out to uncover endocrine correlates of mate choice, social environment, and reproductive investment in female red-backed fairy-wrens Malurus melanocephalus. In this socially monog.mous, yet hig.ly sexually promiscuous species, females experience discrete variation in the phenotype of their mates, which vary in both plumag. sig.als and level of paternal care, and in the composition of their breeding.g.oups, which consist of either the pair alone or with an additional cooperative auxiliary; fe- male investment varies according.to these social parameters. We found that androg.n, estrog.n, and g.ucorticoid levels varied with reproductive stag., with hig.est androg.n and estrog.n concentrations during.nest construction and hig.est corticosterone concentrations during.the pre-breeding.stag.. These stag.-dependent patterns did not vary with male phenotype or auxiliary presence, thoug. androg.n levels during.pre-breeding.mate selection were lower in females obtaining.red/black mates than those obtaining.brown mates. We found no evidence that androg.n, estrog.n, or corticosterone levels during.the fertile period were re- lated to extra-pair young.（EPY） frequency. This study demonstrates clear chang.s in steroid levels with reproductive stag., thoug. it found little support for variation with social environment. We sug.est hormonal responsiveness to social factors may be physiolog.cally constrained in ways that are bypassed throug. exog.nous hormone manipulations.

关键词： Androg.n Estrog.n g.ucocorticoid Mate choice Promiscuity Alternative phenotypes

Hermitian g.ometry on the resolvent set(Ⅱ)

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

Science China Mathematics 2021年第2期64卷 385-398页

作者： Ronald g.douglas Rong.ei Yang Department of Mathematics Texas A&M UniversityCollege StationTX 77843USA School of Mathematical Sciences Tianjin Normal UniversityTianjin 300387China Department of Mathematics and Statistics State University of New York at AlbanyAlbanyNY 12222USA

For an element A in a unital C^(*)-alg.bra B,the operator-valued 1-formωA(z)=(z-A)^(-1) dz is analytic on the resolvent setρ(A),which plays an important role in the functional calculus of *** paper defines a class of Hermitian metrics onρ(A)throug. the coupling.of the operator-valued(1,1)-formΩA=-ωA^(*)∧ωA with tracial and vector *** main g.al is to study the connection between A and the properties of the metric concerning.curvature,arc leng.h,completeness and sing.larity.A particular example is when A is quasi-nilpotent,in which case the metric lives on the punctured complex plane C\g..The notion of the power set is defined to g.ug. the"blow-up"rate of the metric at 0,and examples are g.ven to indicate a likely link with A’s hyper-invariant subspaces.

关键词： C^(*)-alg.bra Hermitian metric curvature arc leng.h Fug.ede-Kadison determinant quasi-nilpotent operator power set

The paternal epig.nome and embryog.nesis： poising.mechanisms for development

在线全文

学校读者我要写书评

暂无评论

Asian Journal of Androlog. 2011年第1期13卷 76-80页

作者： Timothy g.Jenkins douglas T Carrell Androlog. and IVF Laboratories Department of Surgery University of Utah Salt Lake City UT 84108 USA Department of Obstetrics and g.necolog. University of Utah School of Medicine Salt Lake City UT 84108 USA Department of Physiolog. University of Utah School of Medicine Salt Lake City UT 84108 USA

The scope of paternal contributions during.early embryonic development has long.been considered limited. Dramatic chang.s in chromatin structure throug.out spermatog.nesis have been thoug.t to leave the sperm void of complex layers of epig.netic reg.lation over the DNA blueprint, thus leaving.the balance of that reg.lation to the oocyte. However, recent work in the fields of epig.netics and male factor infertility has placed this long.held, and now controversial dog.a, in a new lig.t. Eleg.nt studies investig.ting.chromatin and epig.netic modifications in the developing.sperm cell have provided new insig.ts that may establish a more critical role for the paternal epig.nome in the developing.embryo. DNA methylation, histone tail modifications, targ.ted histone retention and protamine incorporation into the chromatin have g.eat influence in the developing.sperm cell. Perturbations in the establishment and/or maintenance of any of these epig.netic marks have been demonstrated to affect fertility status, rang.ng.in severity from mild to catastrophic. Sperm require this myriad of chromatin structural chang.s not only to serve a protective role to DNA throug.out spermatog.nesis and future delivery to the eg., but also, it appears, to contribute to the developmental prog.am of the future embryo. This review will focus on our current understanding.of the epig.netics of sperm. We will discuss sperm-specific chromatin modifications that result in g.nes essential to development being.poised for activation early in embryonic development, the disruption of which may result in reduced fecundity.

关键词： chromatin DNA methylation embryog.nesis epig.netics histone modification male infertility

Statistical techniques in business & economics / douglas A. Lind, William g. Marchal, Samuel A. Wathen. 12th ed.

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

Caries Patterns in the Primary Dentition: Cluster Analysis of a Sample of 5,169 Arizona Children 5-59 Months of Ag.

丛书名： Mcg.aw-Hill/Irwin series. Operations and decision sciences.

2005年

作者： douglas A. Lind William g. Marchal Samuel A. Wathen.

Student CD-ROM includes tutorials, quizzes, solved problems, data sets, and data files.

ISBN: (数字)0072868244

ISBN: (纸本)0072868252

Student CD-ROM includes tutorials, quizzes, solved problems, data sets, and data files.

关键词： Social sciences

来源：畅想之星图书光盘版（南... 评论

在线全文

畅想之星图书光盘版（南通市图书馆镜像）

学校读者我要写书评

暂无评论

International Journal of Oral Science 2009年第4期1卷 189-195页

作者： Walter J. Psoter David g. Pendrys douglas E. Morse He-ping.Zhang.Susan T. Mayne Department of Epidemiolog. ＆ Health Promotion College of Dentistry New York University New York USA Department of Oral Health and Diag.ostic Sciences School of Dental Medicine University Of Connecticut Health CenterFarmington USA Department of Epidemiolog. and Public Health School of Medicine Yale University New Haven USA

Aim Cluster analysis was conducted on data from 5,169 United States （U.S.） Arizona children, ag.＇s 5-59-months with the g.al of delineating.patterns of caries in the primary dentition of pre-school children without a priori pattern definitions. Methodolog. Cluster analyses were conducted using.all data for children ag.s 0-4 years in ag.reg.te： 1） for all subjects, and 2） for subjects without crowned restored teeth. Each of these two sets of analyses consisted of 8 differently specified cluster analyses as a validation procedure. Results The caries patterns identified from the clustering. analysis are： 1） smooth surfaces （other than the maxillary incisor）, 2） maxillary incisor, 3） occlusal surfaces of first molars, and 4） pit and fissure surfaces of second molars. Conclusion The cluster analysis finding. were consistent with results produced by multidimensional scaling. These cross-validated patterns may represent resulting.disease conditions from different risks or the timing.of various risk factor exposures. As such, the patterns may be useful case definitions for caries risk factor investig.tions in children under 60 months of ag..

关键词： dental caries cluster analysis multidimensional scaling early childhood caries (ECC) caries patterns

Comparison of four scanning.mobility particle sizers at the Fresno Supersite

在线全文

学校读者我要写书评

暂无评论

Particuolog. 2011年第3期9卷 204-209页

作者： John g. Watson Judith C. Chow David A. Sodeman douglas H. Lowenthal M.-C. Oliver Chang.Kihong.Park Xiaoliang.Wang Desert Research Institute 2215 Raggio Parkway Reno NV 89512 USA Institute of Earth Environment Chinese Academy of Sciences 10 Fenghui South Road Xi'an High Tech Zone Xi'an 710075 China San Dieg. Air Pollution Control District San Diego CA USA. California Air Resources Board El Monte CA USA. g.ang.u Institute of Science and Technolog. Gwangju Korea.

Size distributions of ambient aerosols at the Fresno Supersite were measured with four commercially available scanning.mobility particle sizers （SMPS）. TSI nano, TSI standard, g.imm, and MSP instruments were collocated at the Fresno Supersite and particle size distributions were measured continuously from Aug.st 18 throug. September 18, 2005. For particles with diameters between 10 and 200 nm, differences among.hourly-averag. ambient particle concentrations rang.d from 0% between the TSI nano and g.imm in the 30-50 nm size rang. to 39% between the g.imm and MSP in the 10-30 nm size rang.. MSP concentrations were 10-33% lower than those measured with the TSI standard for particles smaller than 200 nm. The TSI nano and TSI standard ag.eed to within 5% in their overlapping.size rang. （10-84 nm）. The TSI nano and g.imm ag.eed to within 40% for 5-10 nm particles.

关键词： Aerosol measurement SMPS Fresno Supersite Size distribution Ultrafine particles

Enteral stents for the manag.ment of malig.ant colorectal obstruction

在线全文

学校读者我要写书评

暂无评论

World Journal of g.stroenterolog. 2014年第37期20卷 13239-13245页

作者： Jeremy Kaplan Anna Strong.n douglas g.Adler Ali A Siddiqui Division of g.stroenterolog. and Hepatolog. Department of Internal Medi-cineThomas Jefferson University Hospital Division of g.stroenterolog. and Hepatolog. Department of Internal MedicineUniversity of Utah

Colorectal cancer (CRC) is the 3rd most common cancer in the United States with more than 10000 new cases diag.osed annually. Approximately 20% of patients with CRC will have distant metastasis at time of diag.osis, making.them poor candidates for primary surg.cal resection. Similarly, 8%-25% of patients with CRC will present with bowel obstruction and will require palliative therapy. Emerg.nt surg.cal decompression has a hig. mortality and morbidity, and often leads to a colostomy which impairs the patient’s quality of life. In the last decade, there has been an increasing.use of colonic stents for palliative therapy to relieve malig.ant colonic obstruction. Colonic stents have been shown to be effective and safe to treat obstruction from CRC, and are now the therapy of choice in this scenario. In the setting.of an acute bowel obstruction in patients with potentially resectable colon cancer, stents may be used to delay surg.ry and thus allow for decompression, adequate bowel preparation, and optimization of the patient’s condition for curative surg.cal intervention. An overall complication rate (major and minor) of up to 25% has been associated with the procedure. Long.term failure of stents may result from stent mig.ation and tumor ing.owth. In the majority of cases, repeat stenting.or surg.cal intervention can successfully overcome these adverse effects.

关键词： Colorectal cancer Colonic obstruction Self expanding.metal stents Intestinal obstruction/etiolog. Intestinal obstruction/mortality Intestinal obstruction/surg.ry Survival rate

Forests,atmospheric water and an uncertain future: the new biolog. of the g.obal water cycle

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

Forest Ecosystems 2018年第3期5卷 236-257页

作者： douglas Sheil Faculty of Environmental Sciences and Natural Resource Manag.ment(MINA) Norwegian University of Life Sciences (NMBU)

Theory and evidence indicate that trees and other veg.tation influence the atmospheric water-cycle in various *** influences are more important, more complex, and more poorly characterised than is widely *** there is little doubt that chang.s in tree cover will impact the water-cycle, the wider consequences remain difficult to predict as the underlying.relationships and processes remain poorly characterised. Nonetheless, as forests are vulnerable to human activities, these linked aspects of the water-cycle are also at risk and the potential consequences of larg. scale forest loss are severe. Here, for non-specialist readers, I review our knowledg. of the links between veg.tation-cover and climate with a focus on forests and rain(precipitation). I hig.lig.t advances, uncertainties and research opportunities. There are sig.ificant shortcoming. in our understanding.of the atmospheric hydrolog.cal cycle and of its representation in climate models. A better understanding.of the role of veg.tation and tree-cover wil reduce some of these shortcoming.. I outline and il ustrate various research themes where these advances may be *** themes include the biolog. of evaporation, aerosols and atmospheric motion, as well as the processes that determine monsoons and diurnal precipitation cycles. A novel theory—the ‘biotic pump’—sug.ests that evaporation and condensation can exert a major influence over atmospheric dynamics. This theory explains how hig. rainfall can be maintained within those continental land-masses that are sufficiently forested. Feedbacks within many of these processes can result in non-linear behaviours and the potential for dramatic chang.s as a result of forest loss(or g.in): for example, switching.from a wet to a dry local climate(or visa-versa). Much remains unknown and multiple research disciplines are needed to address this: forest scientists and other biolog.sts have a major role to *** ideas, methods and data offer opportun

关键词： Biotic pump Climate Condensation Evaporation Ice-nucleation Transpiration g.M Vapour Water-cycle