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41.
A series of 2-alkyl-7, 8-dihydro-3-hydroxynaphtho[1,2-c]chromen-6-ones was synthesised by the condensation of ethyl 3, 4-dihydro-1-oxonaphthalene-2-carboxylate with substituted phenols in the presence of POCl3. The compounds were characterised and tested for their toxicity towards the mycelial growth of seven phytopathogenic fungi in culture. Drechslera oryzae, Rhizoctonia solani and Colletotrichum falcatum exhibited maximum sensitivity to these compounds whereas Macro-phomina phaseolina, Fusarium solani, Alternaria alternata and Pythium aphanidermatum were less sensitive. 2-Ethyl-7, 8-dihydro-3-hydroxy-naphtho[1,2-c]chromen-6-ones possessed greatest toxicity with EC50 values ranging from 0.2 to 2.5 μg ml?1 against all fungi except A. alternata and P. aphanidermatum. 相似文献
42.
Morphological and histochemical changes accompanying testicular development and spermatogenesis have been described in the ruminal trematode Paramphistomum cervi during the course of its infection in sheep. Small testes of 4-week-old worms contain a few primordial germ cells. Spermatogonial cells appear first in 6-week-old worms and increase in number by the 10th week when the testes become large and follicular. Mature spermatozoa appear in the testes of 16-week-old worms. General pattern of spermatogenesis is the same as described for other trematodes, i.e. a single spermatogonium gives rise to 32 spermatozoa. Cytophore is formed at secondary spermatogonial stage. Various spermatogenic stages contain proteins, glycogen and phospholipids, however, the amount of phospholipids decreases as the maturation proceeds. The mature spermatozoa stain strongly with PAS. The enucleated residual mass contains HgBB-positive proteins and lipid granules. The morphological and cytochemical changes occurring during various spermatogenic stages have been correlated with corresponding histoenzymological changes in the cytoplasm. Frequency of spermatogenesis has been worked out which indicates that the transformation of secondary spermatogonia into spermatids is relatively fast as compared to transformation of primary spermatogonia into secondary spermatogonia and stages of spermateleosis. 相似文献
43.
The photochemical degradation of the herbicide isoproturon in aqueous and non-aqueous solutions and in soils has been investigated. Four new photometabolites were formed in non-aqueous solution and three in soil. These were characterised by spectroscopic methods and identified by comparison with authentic synthetic samples such as 3-(4-isopropylphenyl)-1-methylurea; 3-(4-isopropylphenyl)urea; 4,4′-diisopropylazobenzene and 4,4′-diisopropylazoxybenzene. The pathway of formation of these photo products is depicted. 相似文献
44.
S Kumar 《Folia parasitologica》1987,34(3):243-247
Lyophilized somatic antigens obtained from fourth-stage larvae of Bunostomum trigonocephalum induced significant resistance against the development of L4 from L3 and adults from L4. The higher antigen dose (1,000 LE) significantly reduced the number of adults developed from L4 as compared to the lower dose (600 LE) which did so only insignificantly. Inflammation of the intestinal tissue and loosening of the intestinal luminal contents were characteristics of the immunized animals. 相似文献
45.
Mycoplasma synoviae (MS) was isolated from a flock of commercial tom turkeys in which a small percentage of the birds exhibited clinical signs and lesions typical of MS synovitis. However, serologic testing of such flocks revealed poor to inconsistent reactivity by agglutination, enzyme-linked immunosorbent assay (ELISA) or hemagglutination inhibition; isolation of MS from such flocks proved to be very difficult. Turkeys were challenged with one of the isolates (K4463B) either by aerosol or systemically by a combination of intravenous, foot pad, and eyedrop routes. Turkeys challenged by the systemic route responded normally to all serologic tests, whereas those challenged by aerosol either responded very poorly on all serologic tests or were seronegative up to 6 wk postchallenge even though they were positive for MS by tracheal culture. These results suggest that turkeys may harbor an upper respiratory infection with MS while remaining serologically negative. 相似文献
46.
47.
Kumar AM Murtaugh R Brown D Ballas T Clancy E Patronek G 《Journal of veterinary medical education》2001,28(2):73-77
A donor program for procuring dogs and cats to meet the needs of anatomical instruction was initiated six years ago at Tufts University School of Veterinary Medicine. The program was initiated in order to comply with state regulations that preclude the use of shelter animals and to satisfy ethical objections of students and faculty. The donor program has successfully met the animal needs for teaching gross anatomy and, in addition, provides opportunities to integrate clinical perspectives and ethics beginning from the first year of veterinary education. 相似文献
48.
Adsorption-desorption of the herbicide flufenacet (FOE 5043) has been studied in five soils from different locations in India (Delhi, Ranchi, Nagpur, Kerala and Assam) varying in their physicochemical properties. The organic matter (OM) content varied from 0.072 to 0.864%, clay content from 2.5 to 43.7% and pH from 4.45 to 8.35. The adsorption studies were carried out using a batch equilibration technique. Ten grams of soil were equilibrated with 20 ml of aqueous 0.01 M CaCl2 solution containing different concentrations (0-30 mg litre-1) of flufenacet. After equilibration, an aliquot of supernatant was taken out for analysis. During desorption, the amount withdrawn for analysis was replenished with fresh 0.01 M CaCl2 solution and further equilibrated. Desorption studies were carried out with the 30 mg litre-1 concentration of flufenacet only. The adsorption studies revealed that there was moderate to high adsorption of flufenacet considering the comparatively low organic carbon content in the five test soils. Average Kd values ranged from 0.77 to 4.52 and Freundlich KF values from 0.76 to 4.39. The highest adsorption was observed in Kerala soil (OM 0.786%; clay 25%; pH 4.45) followed by Ranchi, Nagpur and Delhi soils, and the lowest in Assam soil (OM 0.553%; clay 2.5%; pH 6.87). The trend in adsorption could be attributed to the chemical nature of flufenacet and the physicochemical properties of the soil such as pH, OM and clay contents. OM and clay contents were positively correlated whereas pH was negatively correlated. Soils having low pH, high OM and high clay contents showed higher adsorption. Desorption studies revealed that there was a hysteresis effect in all the soils. Hysteresis coefficient values (ratio of n(ad) and n(des)) varied from 0.09 to 0.45. The study implies that, because of its moderate to high adsorption, flufenacet is likely to persist in soil for some time. However, the possibility of its movement by leaching or surface run off is less. 相似文献
49.
50.
A leaf curl and mottle disease was observed naturally affecting plants of Trigonella corniculata. A geminivirus was detected in infected plants by PCR using degenerate geminivirus primers and by Southern hybridization with a probe specific to tomato leaf curl begomovirus. This is the first report of a member of the Geminiviridae naturally occurring in T. corniculata. 相似文献