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21.
A new series of substituted 2-anilino-3-methylbutyrates has been prepared; bioassay data for these compounds on Heliothis virescens, Musca domestica, Aphis fabae and Tetranychus urticae are presented and discussed. Some unexpected relationships were observed between the nature of the substituents and the biological activity. Increases in foliar stability were noted with certain substitution patterns. Both α-cyano-3-phenoxybenzyl 3-methyl-2-(α, α, α,2-tetrafluoro-p-toluidino)butyrate and the corresponding 2-(2-chloro-α, α, α-trifluoro-p-toluidino)-3-methylbutyrate showed good stability in air and light, and exhibited biological activities of a similar nature and potency to those of previously known synthetic pyrethroids. Esters of the (R)-2- anilino-3-methylbutyric acids are far more active than those prepared from the (S)-enantiomers. The (R)-configuration at C-2 in these acids is sterically equivalent to the active absolute configuration at the chiral carbon α to the carboxylate group in both the permethrin and the fenvalerate types of pyrethroids. A new class of insecticidal 2-(isoindolin-2-yl)alkanoates is also reported. In this series the most biologically active analogue was α-cyano-3-phenoxybenzyl 3-methyl-2-(4,5,6,7-tetrafluoroisoindolin-2-yl)butyrate. These esters were considerably less stable than the anilino analogues on exposure to air and light.  相似文献   
22.
Survey radiographs have not accurately identified renal contour or location in nonhuman primates. Excretory urography using 786 to 1193 mg iodinelkg body weight resulted in dense opacification of the renal parenchyma and pelvis. Abdominal compression improved visu- alization of the renal pelvis. Interpretation of the nonhuman primate excretory urogram was compromised by several anatomic characteristics of this animal group. Superimposition of the kidneys on the lateral radiograph limited evaluation of the renal contour. Since the renal pelvis in most species of nonhuman primates does not possess diverticula (as in the dog and cat) or a caliceal system (as in the pig and man), the diagnosis of pyelonephritis or renal mass lesions was difficult. Severe irregularities in the renal contour, size of the renal pelvis, or areas of deficient concentrating ability were identifiable in nonhuman primate excretory urograms, but the diagnosis of small cysts was not possible in smaller nonhuman primates. The presence of a caliceal collecting system in the spider monkey (Ateles sp.) suggests this animal as a potential model for the evaluation of human renal disease.  相似文献   
23.
Babesia microti-like piroplasms are a recently recognized cause of illness in dogs in northwest Spain. Our objective was to describe the clinical characteristics and investigate the risk factors for azotemia and death among 58 B microti-like infected dogs. Twenty-one of the 58 (36%) dogs were azotemic at the time that the infection was diagnosed. The case fatality rate during the following week was 22%. Dogs with azotemia at the time of diagnosis were 10 times (95% CI, 3.26-28.8) more likely to die during the following week. Azotemia was the main cause of death for B microti-like infected dogs (attributable fraction = 90%). Severe anemia was present in 45 of the 58 (78%) dogs. Azotemic dogs also presented with hyperphosphatemia, hypoalbuminemia, hypercholesterolemia, proteinuria, and high urine protein: creatinine ratios, suggesting a glomerular component to the disease. Age was the only factor significantly associated with the risk of azotemia (P = .042): on average, a 4-year age increase doubled the risk of an infected dog being azotemic. The only factor significantly associated with mortality was azotemia (P = .001). We concluded that B microti-like infection is associated with a high risk of azotemia and mortality.  相似文献   
24.
Particles emanating from comet 81P/Wild 2 collided with the Stardust spacecraft at 6.1 kilometers per second, producing hypervelocity impact features on the collector surfaces that were returned to Earth. The morphologies of these surprisingly diverse features were created by particles varying from dense mineral grains to loosely bound, polymineralic aggregates ranging from tens of nanometers to hundreds of micrometers in size. The cumulative size distribution of Wild 2 dust is shallower than that of comet Halley, yet steeper than that of comet Grigg-Skjellerup.  相似文献   
25.
对墨西哥大刍草、玉草3号和玉草6号3种不同类型饲草玉米在孕穗期、抽雄期和吐丝期的产量、青贮品质及其营养价值进行了分析。结果表明:品种和生育期对鲜、干草产量有显著影响,而二者之间的交互作用对鲜、干草产量影响不显著;3个品种鲜、干草产量均在吐丝期最高,其中,玉草6号鲜、干草产量极显著高于玉草3号和墨西哥大刍草。从抽雄期及以后,所有饲草玉米干物质(DM)含量均达20%以上,符合青贮对水分的要求。粗蛋白(CP)含量从孕穗期到吐丝期逐渐降低,变幅为8.19%DM~12.80%DM;各时期CP含量均以玉草6号最高,玉草3号和墨西哥大刍草CP含量差异较小。可溶性糖(WSC)含量在孕穗期最高,纤维含量随生育期延长均呈上升趋势。青贮发酵品质在不同生育期差异显著,孕穗期pH值为3.69,乳酸(LA)含量为7.00%DM,发酵品质最优。品种主效应分析表明,玉草6号发酵品质最好,玉草3号和墨西哥大刍草差异不显著。综合分析品种和生育期对青贮发酵品质和营养成分的影响,玉草6号在孕穗期青贮,相对饲用价值达103.28,发酵品质和营养价值最好;玉草3号和墨西哥大刍草在抽雄期青贮发酵品质和营养价值最佳。  相似文献   
26.
Estrogenic plant compounds from the human diet such as the lignan secoisolariciresinol diglucoside (SDG, 1) can exert biological activity in the human body upon ingestion and bioactivation to enterodiol (END, 5) and enterolactone (ENL, 6). Bioavailability of lignans is influenced by the food matrix and gut microbial action, of which the latter is subject to a large interindividual variation. In this study, the fate of the lignan precursor SDG, present in the lignan macromolecule of flax seed ( Linum usitatissimum), was determined during an artificial stomach and small intestinal digestion and during metabolism by two different enterolignan phenotypes in a TWINSHIME environment (TWIN Simulator of the Human Intestinal Microbial Ecosystem). The lignan macromolecule acted as a delivery system of SDG in the large intestine. SDG was only hydrolyzed into secoisolariciresinol (SECO, 2) through microbial action in the ascending colon, after which it was bioactivated into enterolignans from the transverse colon onward. Single demethylation was a first step in the bioactivation, followed by dehydroxylation. Enterolignan phenotypes remained stable throughout the experimental period. The establishment of END and ENL production equilibria reflected the subdominance of ENL-producing bacteria in the gastrointestinal tract.  相似文献   
27.

Context

Multiple ecological drivers generate spatial patterns in species’ distributions. Changes to natural disturbance regimes can place early successional habitat specialists at an increased risk of extinction by altering landscape patterns of habitat suitability.

Objectives

We developed a series of hypotheses to evaluate the effects of landscape structure, fire history, and site-level habitat quality on site occupancy by an early successional specialist, the eastern chestnut mouse (Pseudomys gracilicaudatus).

Methods

We obtained eight years of monitoring data from 26 sites in recently burned heathland in southeast Australia. We used generalised linear models to determine which explanatory variables were related to occupancy. We also explored predictability in patterns of small mammal species co-occurrence.

Results

Landscape structure (patch area, landscape heterogeneity) was strongly related to site occupancy. Site occupancy was associated with dead shrubs in the understory and rock cover on ground layer, but was not directly influenced by recent or historical fire. Contrary to contemporary ecological theory, we found no predictable species associations in our early successional community.

Conclusions

We recommend surveys take account of landscape configuration and proximity to suitable habitat for optimal results. Fire regimes expected to promote eastern chestnut mouse population growth should encourage the retention of critical habitat features rather than be based on temporal rates of successional stages. For management to adequately account for post-disturbance patterns in early successional communities, a species-by-species, multi-scaled approach to research is necessary.
  相似文献   
28.
Mass mortality of Korean catfish, Silurus asotus, occurred in a culture farm situated in Jeollabukdo Province, Korea. The cumulative mortality rates reached up to 5% of the total fish in the farm per day. In clinical signs, the affected fish showed abdominal distension, vent protrusion, enteritis, liver congestion and abscess‐like lesions in enlarged spleen and kidney. Histopathologically, in the liver, hepatocytes lost fat and underwent atrophy or necrosis. The spleen showed necrotized splenocytes and a haemorrhagic pulp. In the kidney, glomerular destruction, degeneration of renal tubular epithelial cell and haemorrhage were observed. However, necrotic muscular lesions were not observed. A pure bacterial isolate was obtained from the liver, spleen and kidney lesions of affected fish. Experimental infection of normal catfish with the isolate resulted in the development of clinical signs similar to those seen on the farm. The isolates were identified as Edwardsiella tarda through biochemical tests (99.4%) and analysis of bacterial genes (16S rDNA) sequences (98%). The bacteria possessed two virulent genes: sodB and katB genes. These results suggest that E. tarda can act as a pathogen of farmed catfish. This is the first report showing that E. tarda caused mortality in cultured Korean catfish.  相似文献   
29.
In coral mariculture, growth is one of the most common ways to track success. However, numerous methods of monitoring coral growth make comparative studies challenging. A literature review of 39 studies from 1982 to 2017 indicated that the most predominant non‐invasive methods used were linear and areal measurement and these were evaluated for their accuracy using nursery‐reared corals. The monthly change in linear and areal growth rates of six coral species (= 215), Pocillopora acuta, Hydnophora rigida, Merulina ampliata, Podabacia crustacea, Echinopora lamellosa and Platygyra sinensis were measured via photogrammetry. We tested whether the planar area of coral colonies can be estimated using three geometric formulas of linear measurements. Based on the literature review, the six types of measurement methods were namely linear, volume, weight, area, count of polyps/branches and calcification, in decreasing order of application. Our results showed that the change in area calculated by geometric mean diameter (GMD) formulas provided the most accurate estimation among the three formulas and was strongly correlated with planar area (R2 ≥ .60; p < .05) for all coral species, except E. lamellosa and Pl. sinensis. However, our findings suggest that it is not ideal to use geometric formulas to estimate the change in area. Instead, we posit that areal photogrammetry represents the simplest yet accurate non‐invasive method for rapid monitoring of extensive areas of corals in situ. Lastly, we discuss the recommendations and limitations for areal photogrammetry.  相似文献   
30.
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