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91.
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分散、乳化条件及成囊工艺对二甲戊灵微 胶囊形成状态的影响 总被引:9,自引:3,他引:9
研究了分散、乳化条件及成囊工艺对以脲醛树脂为壁材采用原位聚合法制备二甲戊灵微胶囊状态的影响。讨论了不同乳化剂及其配比、不同分散乳化时间、搅拌速度、酸化时间和固化温度对微胶囊包封率、粒径大小及分布情况的影响,最终确定以聚丙烯酸钠(PAAS)和苯乙烯-马来酸酐(SMA)按4∶ 1(质量比)混合作乳化剂,1 500 r/min搅拌,分散乳化60 min,酸化90 min,50℃固化90 min作为制备二甲戊灵微胶囊的优化工艺条件。在此条件下可以得到平均粒径10 μm左右、粒度分布均匀的球形微胶囊,包封率在99%以上。 相似文献
93.
以6个苹果品种为试材,进行苹果的有效负载面积与产量相关性试验.结果表明:在一定条件下,有效负载面积(EBS)越大,产量相应越高.不同纬度对不同品种的EBS和产量的影响不同.土壤中砾石含量对EBS和产量都有影响,但品种和砧木不同,EBS的减少率不同.不同品种对砾石的耐受能力不同. 相似文献
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Empirical relationships between land use/cover and estuarine condition in the Northeastern United States 总被引:1,自引:0,他引:1
Wilfrid Rodriguez Peter V. August Yeqiao Wang John F. Paul Arthur Gold Norman Rubinstein 《Landscape Ecology》2007,22(3):403-417
Land–water interactions were examined in three regions in the Virginian Biogeographic Province; the southern shore of Cape
Cod, Massachusetts; the Hudson/Raritan region of New York; and the eastern shore of the Delmarva (Delaware/Maryland/Virginia)
Peninsula. Cumulative distribution functions were used to evaluate similarity in environmental condition among estuaries.
Spatial-setting variables (location in a river, coastal lagoon, or in open waters) were associated with variation for some
measures of estuarine condition. Patterns of coastal urban and agriculture gradients were measured and their relationship
with indicators of estuarine condition was modeled statistically. When estuaries were pooled, the highest variation explained
by spatial-setting variables was found for dissolved oxygen (DO, R
2 = 0.44) and salinity (R
2 = 0.58), with DO decreasing in river locations and salinity decreasing with rainfall and sampling locations near rivers.
The explanatory power for the other indicator variables was low and varied from 6% to 27%. Rainfall explained some of the
variation (R
2 = 0.23) in total suspended solids. Moderate (0.4 < | r | < 0.7) to strong (| r | ≥ 0.7) linear associations were found between total urban area and measures of estuarine condition. Within regions, total
urban area was positively associated with Silver (r = 0.59), Cadmium (r = 0.65), and Mercury (r = 0.47) in Cape Cod, and inversely related to DO (r = −0.65) in the Hudson/Raritan region. No associations were found in the Delmarva Peninsula study area. Total area of agriculture
showed a moderate association with Arsenic in Cape Cod, but no other associations were found in the other two regions. Our
analyses show a measurable impact of urban land use on coastal ecosystem condition over large areas of the northeastern United
States. This pattern was most evident when many different landscapes were considered simultaneously. The relationship between
urban development and estuarine condition were weaker within the individual regions studied. The use of land use/cover models
for predicting estuarine condition is a challenging task that warrants enhancements in the type, quantity, and quality of
data to improve our ability to discern relationships between anthropogenic activities on land and the condition of coastal
environments. 相似文献
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Abstract – We studied eel population characteristics (size classes, densities and body condition) in the lower Loire River floodplain (France) to evaluate the effects of longitudinal and lateral gradients. A total of 36 sites were electrofished in June 2005. The sites were grouped first into three river segments according to the distance inland corresponding to a longitudinal gradient and secondly into three lateral connectivity categories. Results indicate that small eels, especially those ≤300 mm, were very abundant downstream but density rapidly decreased upstream. In addition, eels ≤150 mm tended to be most abundant in connected waterbodies. Conversely, the distribution of larger eels was quite uniform across both dimensions. Eel condition decreased upstream. In parallel, in downstream river segment, eels had a lower condition in disconnected waterbodies than in connected ones. Eel specialists still have only a longitudinal perception of eel habitat. Our results suggest that lateral gradients should be also taken into consideration. 相似文献
100.
The effect of variations in the amount or quality of food provided on the amino acid profile of larvae, was tested in two marine fish species, the Senegal sole (Solea senegalensis) and the sea bass (Dicentrarchus labrax). The objective was to assess whether such nutritionally suboptimum dietary patterns, which simulate situations that may occur in hatcheries, result in variations in the concentration of one or more amino acids that could be used as indicators of nutritional condition of larvae. Restriction in the normal food ration by 60% had no clear effect on the amino acid profile of sea bass, while the concentration of some amino acids (Arg, Ala and Phe) showed significant variations in sole. Feeding on artificial diets, which have shown their inadequacy a priori, resulted also in no significant effect on the profile of sea bass, but in a dramatic modification of the amino acid profile in sole. In addition, changes in the amino acid profiles considered as a whole were evaluated using the cluster analysis instead of paired comparisons between amino acid concentrations in each treatment. The analysis clearly separated profiles of larvae fed restrictedly or inadequately from their controls, irrespective of the species. This demonstrated the potential value of evaluating whole changes in amino acid profile as nutritional indicator. Besides, it was demonstrated that sensitivity of larvae to nutritional changes that may be reflected in the amino acid profile is greatly conditioned by the species and developmental stage. 相似文献