A Review on Ozone Evolution and Its Relationship with Boundary Layer Characteristics in Urban Environments   总被引：1，自引：0，他引：1  

Nelson Y. O. Tong  Dennis Y. C. Leung  Chun-Ho Liu 《Water, air, and soil pollution》2011,214(1-4):13-36

This paper reviews the interrelationship among boundary layer, urbanization, and evolution of ozone, with particular emphasis on how boundary layer dynamics and urbanization affects the evolution of ozone under different meteorological and climatological conditions. The aim of this work is not only to provide an exhaustive investigation of individual ozone episodes but to look at the underlying issues and hypotheses that are available for understanding the evolution of ozone. The review concludes with a summary of the current state of knowledge and outlines some of the remaining questions. It is the intention of this paper to serve as an ecumenical reference to the community for reappraising the relation of boundary layer climate to the evolution of ozone in an urban setting, especially on a peculiar feature of ozone dynamic, nocturnal ozone maxima. To date, there is still no overarching consensus on the mechanisms that lead to its formation. The importance of levels of urbanization and advantage of ascertaining the substantial weights of the respective mixing height and emission structure in exploring the relationship between ozone evolutions should not be overlooked.  相似文献   

The rice genome. The most precious things are not jade and pearls     

Ronald P  Leung H 《Science (New York, N.Y.)》2002,296(5565):58-59

  相似文献   

Vascular endothelial growth factor is a secreted angiogenic mitogen   总被引：324，自引：0，他引：324  

D W Leung  G Cachianes  W J Kuang  D V Goeddel  N Ferrara 《Science (New York, N.Y.)》1989,246(4935):1306-1309

Vascular endothelial growth factor (VEGF) was purified from media conditioned by bovine pituitary folliculostellate cells (FC). VEGF is a heparin-binding growth factor specific for vascular endothelial cells that is able to induce angiogenesis in vivo. Complementary DNA clones for bovine and human VEGF were isolated from cDNA libraries prepared from FC and HL60 leukemia cells, respectively. These cDNAs encode hydrophilic proteins with sequences related to those of the A and B chains of platelet-derived growth factor. DNA sequencing suggests the existence of several molecular species of VEGF. VEGFs are secreted proteins, in contrast to other endothelial cell mitogens such as acidic or basic fibroblast growth factors and platelet-derived endothelial cell growth factor. Human 293 cells transfected with an expression vector containing a bovine or human VEGF cDNA insert secrete an endothelial cell mitogen that behaves like native VEGF.  相似文献   

水稻抗稻瘟病鉴定中的几个相关问题的探讨   总被引：6，自引：0，他引：6  

何月秋  唐文华 《云南农业大学学报(自然科学版)》2003,18(3):234-238

 利用CO39近等基因系及其累加系和4个稻瘟病菌的原始菌株及其突变体,研究稻瘟病抗性鉴定中经常考虑的几个因子。结果表明,接种孢子量与植株的病级、病斑数和发病叶面积呈正相关,品种对混合菌株接种的抗病性主要取决于致病性强的菌株,弱菌株的诱导抗性有限,过量施用氮肥可使部分抗病品种感病,被克服的主效基因没有明显的残效抗性。  相似文献   

Analytical challenges: determination of tetrodotoxin in human urine and plasma by LC-MS/MS     

Leung KS  Fong BM  Tsoi YK 《Marine drugs》2011,9(11):2291-2303

Tetrodotoxin (TTX) is a powerful sodium channel blocker found in puffer fish and some marine animals. Cases of TTX poisoning most often result from puffer fish ingestion. Diagnosis is mainly from patient's signs and symptoms or the detection of TTX in the leftover food. If leftover food is unavailable, the determination of TTX in the patient's urine and/or plasma is essential to confirm the diagnosis. Although various methods for the determination of TTX have been published, most of them are for food tissue samples. Dealing with human urine and blood samples is much more challenging. Unlike in food, the amount of toxin in the urine and blood of a patient is generally extremely low; therefore a very sensitive method is required to detect it. In this regard, mass spectrometry (MS) methods are the best choice. Since TTX is a very polar compound, there will be lack of retention on conventional reverse-phase columns; use of ion pair reagent or hydrophilic interaction liquid chromatography (HILIC) can help solve this problem. The problem of ion suppression is another challenge in analyzing polar compound in biological samples. This review will discuss different MS methods and their pros and cons.  相似文献   

Quantification of Zeaxanthin Dipalmitate and Total Carotenoids in <Emphasis Type="Italic">Lycium</Emphasis> Fruits (Fructus Lycii)     

Peng Y  Ma C  Li Y  Leung KS  Jiang ZH  Zhao Z 《Plant foods for human nutrition (Dordrecht, Netherlands)》2005,60(4):161-164

An HPLC-DAD method has been developed to quantitatively analyze for the content of zeaxanthin dipalmitate, a major carotenoid in Fructus Lycii, in different species of the genus Lycium. Determination was performed using an Alltima C18 column with the mobile phase consisting of acetonitrile and dichloromethane (42:58). The total contents of carotenoids in these samples were also determined by using UV spectrophotometric assay. Total carotenoid concentrations of different Fructus Lycii are within the range of 0.03–0.5%. Zeaxanthin dipalmitate is a predominant carotenoid, comprising 31–56% of the total carotenoids in Fructus Lycii. This study is the first systematic quantification of the carotenoids in the fruits of different Lycium species. The results demonstrated that these methods are reliable and facile techniques for rapid analysis of carotenoids for crude drug and plant-derived food supplements.  相似文献   

AN EXPLORATORY PERFORMANCE ASSESSMENT OF SHRIMP EXPORTERS FOR THE U.S. MARKET     

Run Yu  Junning Cai  PingSun Leung 《Aquaculture Economics & Management (Blackwell Science)》2013,17(4):225-251

This paper develops a systematic approach for the assessment of export performance and applies it to evaluate the major shrimp exporters for the U.S. market during the period from 1991 to 2007. Export performance is evaluated from two perspectives: (1) an individual exporter's competitiveness in a specific shrimp product in terms of comparative advantage, and (2) an individual exporter's overall competitiveness in the U.S. market in terms of specialization.  相似文献   

Effects of Pomegranate Juice Supplementation on Pulse Wave Velocity and Blood Pressure in Healthy Young and Middle-aged Men and Women   总被引：2，自引：2，他引：0  

Lynn A  Hamadeh H  Leung WC  Russell JM  Barker ME 《Plant foods for human nutrition (Dordrecht, Netherlands)》2012,67(3):309-314

Pomegranate juice may improve cardiovascular risk because of its content of antioxidant polyphenols. We conducted a randomized placebo-controlled parallel study to examine the effect of pomegranate juice on pulse wave velocity (PWV), blood pressure (BP) and plasma antioxidant status (ferric reducing power; FRAP) in 51 healthy adults (30-50?years). Participants consumed 330?ml/day of pomegranate juice or control drink for four?weeks. Measurements were made at baseline and at four?weeks. There was no effect of the intervention on PWV (P?=?0.694) and plasma FRAP (P?=?0.700). However, there was a significant fall in systolic blood pressure (-3.14?mmHg, P?相似文献   

A mixed model for investigating a population of asymptotic growth curves using restricted B-splines     

Geoffrey Jones  Joyce Leung  Hugh Robertson 《Journal of Agricultural, Biological & Environmental Statistics》2009,14(1):66-78

We introduce a new method for modeling a population of growth curves with B-splines, adapting the usual regression spline basis to ensure a horizontal upper asymptote in all fitted curves. The new method is easily implemented in standard statistical software. We motivate and illustrate our method using data on the growth of Brown Kiwi (Apteryx mantelli) in the North Island of New Zealand, including a time-dependent covariate to investigate the effects of different rearing environments on patterns of weight increase.  相似文献   

Infection of cattle in Queensland with bluetongue viruses: 1. prevalence of antibodies     

MP WARD  M. FLANAGAN†  FC BALDOCK† 《Australian veterinary journal》1995,72(5):182-186

SUMMARY A survey of nearly 20 000 cattle in Queensland was conducted to describe the prevalence and distribution of infection by serotypes of bluetongue virus. The overall prevalence of serum antibodies to one or more bluetongue viruses was 8.7% (95% confidence interval 8.3 to 9.1). Sera from cattle contained neutralising activity against 2 serotypes, 1 and 21. No evidence was found of infection with other serotypes previously isolated in Australia. The overall prevalence of serotype 1 antibodies was 7.7% (95% CI 7.3 to 8.0) and the prevalence of serotype 21 antibodies was 3.3% (95% CI 3.1 to 3.6). The prevalence of serotype 1 antibodies was significantly (P < 0.05) higher than that of serotype 21 in every region of the State, except in the central highlands and south-west Queensland. Overall, 3 significantly (P < 0.05) different zones of prevalence were found: high prevalence (> 20%) in far north Queensland, moderate (5 to 20%) in north-west, northern and southern coastal Queensland, and low (< 5%) in the central highlands, Darling Downs and south-west Queensland.  相似文献