感应电动势与参照系的相对关系

本文从电磁场变换入手,举例说明感应电动势的大小及区分感生、动生电动势与参照系有关.     

衍生化气相色谱法测定黄磷诱发氧化水中苯酚降解产物

利用衍生化气相色谱法对黄磷诱发氧化苯酚降解产物进行了研究，在磷酸存在下，以甲醇作酯类衍行生试剂，分别和ＳＥ－５２和ＨＰ－１７石英毛细管双柱结合ＧＣ－ＭＳ进行分离定性定量，黄磷诱发氧化苯酚降解产物以羧酸为主，在反应温度５０℃时，表现为一级反应特征，速率常数（Ｋ）：０．０７７ｍｉｎ＾－１，半衰期（ｔ１／２）：９．０ｍｉｎ。     

A Preliminary Study of Geographic Influence on Arsenic Concentrations in Human Hair

Past mining activities in the county of Cornwall in the United Kingdom, has exposed the local environment to raised levels of As. Previous research has shown an increased concentration of As in crops grown in such areas and the subsequent take-up of As through the food chain may lead to an increased body burden in man. In an attempt to evaluate this, a pilot study was carried out using Particle Induced X-ray Emission to compare the hair As concentration of a group of Cornish residents to that of a control group consisting of residents in the counties of Oxfordshire and Wiltshire. The null hypothesis being that there is no significant difference between the hair As concentrations of the two groups.Each group comprised thirty six age and sex matched subjects. The mean hair As concentration for the Cornish group was 2.51 g g-1, which is significantly greater than that of 0.7 g g-1 found in the control group (p = 0.004). The World Health Organisation suggests a hair As value greater than 1 g g-1 as evidence of increased exposure to As and 5 g g-1 is quoted by the Canadian Government as evidence of significant ingestion of As. Twenty one Cornish subjects registered a value at or above 1 g As g-1 compared to nine in the control group (p = 0.0003). Five subjects in the Cornish group had values that exceed 5 g As g-1, compared to only two in the control group (p = 0.23). We use the results of this study as evidence to support our continued work in this area in order to evaluate possible health implications.     

王锦蛇的无冬眠饲养试验

2004年11月～2005年4月，进行了王锦蛇的冬眠期饲养试验．结果表明：在王锦蛇的冬眠期内，人工保持其环境温度为25～30℃，相对湿度为60％～85％，并提供其所需要的食物条件，就能够使王锦蛇在冬眠期内正常地生长发育，不仅能缩短其饲养时间，而且能提高其成活率，从而达到高效饲养王锦蛇的目的．     

Is helping a beneficial learning experience for red-cockaded woodpecker (Picoides borealis) helpers?

Several hypotheses have been suggested to explain the evolution and maintenance of helping behavior in cooperatively breeding birds, one of which we investigated in the red-cockaded woodpecker (Picoides borealis). Helping may provide a learning experience that improves reproductive success once the helper becomes a breeder. We used data collected from a population of red-cockaded woodpeckers in the Sandhills of North Carolina to compare the reproductive success of 2-year-old breeders that were helpers at age 1 (helping experience) to those that were floaters or solitary males at age 1 (no helping experience). Reproductive success of the two groups was similar, indicating that helping provides no experience useful in reproduction. We reject the learning experience hypothesis as an explanation for the maintenance of helping behavior in red-cockaded woodpeckers. Received: 29 July 1996 / Accepted after revision: 27 April 1997     

Plasma levels of androgens and gonadal development of breeders and helpers in the bell miner (Manorina melanophrys)

Plasma concentration of androgens and gonad development were studied in wild cooperatively breeding bell miners (Manorina melanophrys) of different age, sex and social status. Plasma levels of androgens increased with age of birds. For sexually mature (SM) bell miners, androgen levels were higher in breeders than in nonbreeding (NB) helpers (P < 0.005), and they were marginally higher in females than in males (P < 0.10). Thus female breeders showed the highest plasma levels of androgens. This pattern may be explained by an asymmetry between the sexes in the levels of competition needed to reach and defend breeding status; the degree of intra-sexual competition seems to be higher among female bell miners than among males. In general, male breeders had larger gonads than male SMNB helpers; male breeder gonads produced spermatozoa whereas most helpers' gonads did not. However, old (i.e. 34 months) SMNB male helpers had large gonads producing spermatozoa in spite of having low plasma levels of androgens. We suggest that young male bell miners may be under a voluntary mechanism of reproductive suppression perhaps favoured by inbreeding avoidance; although some aggressive interactions observed between very young helpers (about 2 months) and adult members of the breeding unit suggests that a certain degree of imposition also occurs at young ages. Older male helpers may avoid aggression with the male breeder and imposed reproductive suppression, hence the low circulating levels of androgens, but they have the potential to sneak extra-pair copulations. Gonad size decreased during the non-breeding season in both sexes.     

Effects of Climate and Land-Use Change on Species Abundance in a Central European Bird Community

Abstract:  Although it is known that changes in land use and climate have an impact on ecological communities, it is unclear which of these factors is currently most important. We sought to determine the influence of land-use and climate alteration on changes in the abundance of Central European birds. We examined the impact of these factors by contrasting abundance changes of birds of different breeding habitat, latitudinal distribution, and migratory behavior. We examined data from the semiquantitative Breeding Bird Atlas of Lake Constance, which borders Germany, Switzerland, and Austria. Changes in the regional abundance of the 159 coexisting bird species from 1980–1981 to 2000–2002 were influenced by all three factors. Farmland birds, species with northerly ranges, and long-distance migrants declined, and wetland birds and species with southerly ranges increased in abundance. A separate analysis of the two decades between 1980–1981 and 1990–1992 and between 1990–1992 and 2000–2002 showed that the impact of climate change increased significantly over time. Latitudinal distribution was not significant in the first decade and became the most significant predictor of abundance changes in the second decade. Although the spatial scale and temporal resolution of our study is limited, this is the first study that suggests that climate change has overtaken land-use modification in determining population trends of Central European birds.     

Emission of oilseed rape volatiles after pollen beetle infestation; behavioural and electrophysiological responses in the parasitoid <Emphasis Type="Italic">Phradis morionellus</Emphasis>

Summary. The pollen beetle, Meligethes aeneus, is an important pest of oilseed rape, Brassica napus. Larvae of this species feed only in the buds and flowers of Brassicaceae. One important natural enemy of this beetle is the parasitoid Phradis morionellus that attacks larvae in buds and flowers and also feeds on the flowers. The preferences for odours of non-infested and infested rape were tested for both starved and fed parasitoids in Y-tube olfactometer experiments. The volatile blend released from pollen beetle-infested and non-infested flowering rape and from pollen beetle larvae was identified and quantified. Gas chromatography-electroantennodetection analyses were performed with female P. morionellus. Parasitoids in both treatment groups preferred infested rape, but the proportion of responding female P. morionellus was significantly lower for the group that was starved. Six of the 20 volatiles identified were released at higher rates from infested rape than from non-infested. None of these compounds was found in pollen beetle larvae headspace. P. morionellus antennae detected both major and minor components in the volatile blend. The volatiles released at a significantly higher rate from infested rape and detected by P. morionellus antennae were (Z)-3-hexenylacetate, (Z)-3-hexenol, 3-butenyl isothiocyanate and (E,E)-α-farnesene.     

转pBinMoBc基因棉花的培育与应用

采用农杆菌介导法将含有复合OM启动子和增强子Ω因子的外源基因pBinMoBc导入冀棉20中.转化再生株经分子检测表明,外源基因已整合到转基因植株基因组内,并得到了表达,转化外源基因插入拷贝数是1~2个.转化后代材料经6~7代选育为纯合品系2001pb-3.2001pb-3抗虫性较好,每公顷产皮棉1534.5kg,比对照增产18.68%.图5表3参4     

Reproductive partitioning in communally breeding guira cuckoos,<Emphasis Type="Italic"> Guira guira</Emphasis>

Guira cuckoos, Guira guira, exhibit a rare polygynandrous reproductive system with groups containing several male and female breeders, allowing for important tests of reproductive skew models. Female reproductive strategies involve leaving the group, varying clutch size, egg ejection and infanticide, among others. Here we examined the predictions of reproductive skew models relative to reproductive partitioning among females in groups. We used yolk protein electrophoresis to identify individual females eggs in joint nests. We found that reproductive partitioning favors early-laying females, which lay and incubate more eggs than females that begin laying later. Because the female that lays first tends to switch between repeated nesting bouts, and females do not always contribute eggs to each bout, female reproductive success tends to equalize within groups over time. The pattern of reproductive partitioning differs from that described for anis, another crotophagine joint-nester. We calculated reproductive skew indices for groups in 2 years, for both laying and incubation, as well as an overall population value. These were compared to random skew generated by simulations. Varying degrees of skew were found for different groups, and also across sequential nesting bouts of the same groups. Overall, however, skew did not deviate from random within the population. Nests that reached incubation tended to have lower skew values during the laying phase than nests terminated due to ejection of all eggs followed by desertion. Groups had higher reproductive skew indices in their first nesting bout of the season, and these nests frequently failed. These results illustrate the importance of social organization in determining not only individual, but group success in reproduction, and highlight the flexibility of vertebrate social behavior.Communicated by J. Dickinson