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881.
Ashok Kumar Pandey Shri Dhar Pandey Virendra Misra P. N. Viswanathan 《Chemistry and Ecology》1999,16(4):269-282
In order to investigate the role of functional groups present in humic acid(s) (HA) during complex formation, water soluble complexes between HA isolated from soil and metals (Pb, Ca, As, Ni, Cr, Co, Cu, Cd, Fe, Mn, Mg and Zn) were prepared and subjected to infrared (IR) spectroscopy. the IR data revealed the involvement of the - OH group of humic acid in complex formation with all metals except copper and arsenic, whereas the - COOH group of HA was found to be the preferred site of binding for all the metals. the significance of findings in relation to detoxification of environmental pollutants is discussed in this paper. 相似文献
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The purpose of this review was to summarize the literature on occupational, acute, traumatic hand injury and suggest directions for future research. In 1996, the leading occupational injury treated in United States' hospital emergency departments was an acute hand injury (e.g. laceration, crush or fracture). These injuries affected 30% of an estimated 3.3 million injured workers (990,000). Cuts and lacerations of the fingers ranked third after back and leg strains in the number of lost workday cases in the USA in 1994. The incidence rate of hand injuries studied in seven manufacturing environments around the world ranged from 4 to 11 per 100 workers per year. Workers aged 24 years or less had the highest risk of hand injury. Men had higher rates of severe hand injury than women.Despite the high frequency and significant amount of lost work time associated with these injuries, they are poorly understood from an etiological perspective. There is only one case-control study of occupational hand injury in the literature. That study suggested an important role for both fixed (age) and transient risk factors (doing an unusual task) at the time of the injury. More analytic epidemiological research is needed to identify potentially modifiable risk or protective factors (e.g. glove use) for acute hand injuries. In this regard, the case-crossover design, a relatively new epidemiological approach using cases as their own controls, could prove an efficient method for determining transient, modifiable risk factors for acute, occupational hand injury. 相似文献
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P Leone M Nègre M Gennari V Boero R Celis J Cornejo 《Journal of environmental science and health. Part. B》2001,36(2):127-142
Adsorption of the imidazolinone herbicides imazapyr, imazethapyr and imazaquin was studied on two binary systems (ferrihydrite-humic acid) prepared by treating ferrihydrite (Fh) immediately after its precipitation with a soil humic acid (HA) at different loadings (4% and 8% HA content), and on a blank ferrihydrite sample prepared in the same way, but without HA addition. Imidazolinone adsorption on pure Fh and on the 4% Fh-HA decreased with increasing of the herbicide hydrophobicity (imazaquin相似文献
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Abstract: Because ambient temperature strongly influences reproduction in frogs, the seasonal timing of frog calling provides a sensitive index of biotic response to climate change. Over the last century, daily temperatures increased during 5 of the 8 months key to gametogenesis in frogs and toads near Ithaca, New York ( U.S.A.). Earliest dates of calling frogs recorded by Albert Hazen Wright between 1900 and 1912 near Ithaca were compared to those from the New York State Amphibian and Reptile Atlas Project for 1990–1999 for the three counties surrounding Ithaca. Four species are now calling 10–13 days earlier, two are unchanged, and none is calling later. The data suggest that climate has warmed in central New York State during this century and has resulted in earlier breeding in some amphibians—a possible first indication of biotic response to climate change in eastern North America. 相似文献
890.
Honey-bee (Apis mellifera) colonies exhibit extreme reproductive division of labour. Workers almost always have inactive ovaries and the queen monopolises
egg laying. Although extremely rare, ’anarchistic’ colonies exist in which workers produce male offspring despite the presence
of the queen. By comparing the rates of ovary activation in anarchistic and wild-type bees fostered to host colonies of different
genotype (i.e. anarchist and non-anarchist) and queen status (i.e. queenless and queenright), we investigated the factors
involved in inhibiting ovary activation. Fostered anarchist workers always had a higher level of ovary development than fostered
wild-type bees in both anarchist and non-anarchist host colonies. Fostered workers of both genotypes had more active ovaries
in anarchistic than in wild-type hosts. Fostered workers of both strains also had more active ovaries in queenless than in
queenright hosts. The results suggest that selection for worker reproduction in the anarchistic line has both reduced the
effects of brood and queen pheromones on worker ovary inhibition and increased the likelihood that workers of the anarchistic
line will develop ovaries compared to wild-type workers.
Received: 14 June 2000 / Revised: 26 September 2000 / Accepted: 7 October 2000 相似文献