Science and technology can make substantial contributions to socio-economic development in Thailand. In order to promote such contributions, problem areas and specific problems of high priority need to be defined, and possible solutions outlined. Important criteria for selecting priority areas and key problems include relevance to development, the availability of human resources and the possibility of their development, the cutting-edge advantage to be gained by development, the possibility of international collaboration, and the possibility of integration with culture and environment. These criteria suggest in Thailand a focus on the development of bioscience and biotechnology, materials science, electronics, and information science. 相似文献
In contrast to many corals of the Great Barrier Reef, Australia, which are synchronous multispecific spawners, the abundant coral species in the northern Red Sea, Israel, exhibit temporal reproductive isolation. Spawning dates of 12 of the 13 Red Sea species followed lunar periodicity and were consistent throughout 3 years of study. Spawning periods of all species occurred in different seasons, different months, or different lunar phases within the same month. The high abundance of the corals studied at Eilat may be due in part to the advantages gained through not having overlapping spawning periods and settlement times. 相似文献
Twenty-eight piglets coming from a "specific pathogen free" herd were inoculated at three days of age with 50 000 or 100 000 sporulated oocysts of Isospora suis. Fecal samples were examined for oocyst shedding daily and several clinical parameters were recorded. Ten piglets were used as normal controls. Groups of piglets were euthanized from three days to 12 days postinoculation and routine necropsies were performed. Bacteriological, virological, parasitological and histopathological examinations were made on the intestinal tracts. The incubation period was four to five days. Clinical signs and microscopic intestinal lesions observed in the experimentally infected animals were similar to those reported in spontaneous cases of porcine neonatal coccidiosis. Lesions of villous atrophy in the small intestine seemed to result from the destruction of villous epithelial cells mainly during the peak of asexual reproduction which occurred around four to five days postinoculation. Intracellular coccidial organisms were difficult to find during the late atrophic and villous regrowth stages of the intestinal lesions. The prepatent period varied from four to seven days and the most common was five days. Eighty percent of the piglets kept alive more than four days postinoculation have shed oocysts. Piglets dosed with old sporulated oocysts (ten months old) shed many more oocysts than those infected with a fresh inoculum (less than two months old). The patent period was not determined precisely with the design of the experiment but some of the infected piglets shed oocysts for at least five days. 相似文献
Summary. Studies were conducted to determine the influence of pyrazon (5-amino-4-chloio-2-phenyl-3(2H)-pyridazinone) on photosynthesis. A strong inhibiting effect on O2 evolution from leaf discs of several species was recorded. For most species a concentration of 5 × 10−5 M caused a reduction of about 50% in the rate of photosynthesis. Photosynthesis of sugar beet, highly resbtant to pyrazon, was reduced to 50% by a concentration of 7–5 × 10−5 M. Since these differences cannot account for the great divergence in susceptibility to pyrazon, it is suggested that the selectivity of this herbicide results from degradation and differential accumulation in the foliage. Pyrazon was phytotoxic to plants of tomato and pigweed (Amaranthus retrofiexus L.) kept in the light but not when kept in the dark, after foliage application. The conclusion that pyrazon inhibits the mechanism of photosynthesis and causes starvation for carbohydrates, was strengthened by the fact that external feeding of glucose overcame the toxicity of the compound in tomato plants. These results and a possible mode of selectivity are discussed. 相似文献
Although most of the magnetic flux observed on the sun originates in the low-latitude sunspot belts, this flux is gradually dispersed over a much wider range of latitudes by supergranular convective motions and meridional circulation. Numerical simulations show how these transport processes interact over the 11-year sunspot cycle to produce a strong "topknot" polar field, whose existence near sunspot minimum is suggested by the observed strength of the interplanetary magnetic field and by the observed areal extent of polar coronal holes. The required rates of diffusion and flow are consistent with the decay rates of active regions and with the rotational properties of the large-scale solar magnetic field. 相似文献
Lungs from 48 feedlot cattle that had died from bacterial pneumonia were examined grossly and microscopically. Criteria based on microscopic lesions were adopted to age these pneumonias. In 38 cases, pneumonic lesions were of relatively uniform age throughout the affected tissue. In eight other cases, the presence of older lesions confined to one or two lobes suggested a previous episode of pneumonia. The aging criteria adopted were in agreement with the duration of the observed clinical signs in 26 cases. In 13 other cases, the pneumonia was estimated to be of longer duration than suggested by the history, whereas in the remaining nine cases, it was estimated to be more recent. Areas of tan discoloration of the parenchyma surrounded by white or yellow borders were considered the best areas to examine microscopically since they offered the best chances of revealing necrosis and fibrosis, the main lesions used to age the pneumonia. 相似文献
1. A novel glutathione peroxidase, which is distinct from tetrameric glutathione peroxidase, was purified to homogeneity from a broiler chick liver cytosolic fraction using 5 different column chromatographic methods.
2. The enzyme in cytosol was separated from ‘classic’ tetrameric glutathione peroxidase and glutathione S‐transferases by DEAE‐Sephacel and Sephadex G‐100 chromatographies and further purified by Mono Q, hydroxylapatite and sulphobro‐mophthalein‐S‐glutathione‐agarose chromatographies.
3. The molecular weight of the purified enzyme determined by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis was 19,500 and that found by gel filtration chromatography was comparable. This indicates that the enzyme protein is a single polypeptide. The isoelectric point of the enzyme was determined as 7.0 by polyacrylamide gel isoelectric focusing.
4. The purified enzyme catalysed the reduction of hydrogen peroxide, cumene hydroperoxide, tert‐butyl hydroperoxide and linoleic acid hydroperoxide. Furthermore, it reduced phosphatidylcholine hydroperoxide in the absence of phospholi‐pase A2. The optimum pH for the enzyme reaction was 7.0. The antiserum against the purified enzyme reacted with the 19.5 kDa polypeptide in the liver cytosol of duck and quail. 相似文献
1. Extra and intramineral eggshell matrix proteins were solubilised before and after demineralisation by sequential extractions using guanidine hydrochloride and EDTA.
2. The intramineral electrophoretic profile of SDS‐PAGE showed the presence of 80, 66, 43, 36 and 15 kDa bands with a predominance of a 17 kDa band. In the extramineral part, the major protein was the 15 kDa band.
3. The introduction of intramineral extract to a metastable solution of calcium carbonate delayed the rate of crystal growth. The delay in the rate of precipitation was elicited by a single fraction (MW 50–80 kDa), isolated by gel filtration chromatography, of eggshell extracts. Extramineral extracts had no effect.
4. Addition in vitro of intramineral eggshell extracts modified the morphology of calcite; the crystals aggregated and showed irregular surfaces.
5. These observations suggest that constituents of the eggshell matrix are involved in the control of calcite growth and crytallographic structure of the hen's eggshell. 相似文献