共查询到20条相似文献，搜索用时 140 毫秒
1.
本文利用微胶囊技术,以豚草提取物为囊芯材料,明胶为囊壁材料,采用单凝聚法制备豚草提取物植物源农药微胶囊剂,设计正交试验并对其性能进行表征。结果表明:豚草提取物微胶囊最优配比方案为明胶质量浓度5 g·L-1,芯壁比1:2,搅拌速度200 r·min-1,乳化时间90 min。其中,四因素对成囊影响由大到小排列顺序为,明胶质量浓度>搅拌速度>乳化时间>芯壁比。从扫描电子显微镜成像图片可以看出,微胶囊形状规则、表面光滑。微胶囊中位径为20.55μm,大部分粒径大小分布在18.23～33.31μm间。豚草提取物微胶囊剂缓释效果优于豚草提取物。 相似文献
2.
《林产化学与工业》2015,(5)
以明胶、阿拉伯胶和麦芽糊精复配作为壁材,蔗糖酯和聚氧乙烯脱水山梨醇单油酸酯(吐温-80)为乳化剂,采用超声波乳化-均质-喷雾干燥工艺制备角鲨烯微胶囊产品。对超声波乳化工艺、壁材配比、乳化剂添加量以及喷雾干燥等参数进行了研究,并将优化工艺所制备的产品与冷冻干燥法制备微胶囊进行比较。结果表明,产品的最佳工艺为:角鲨烯3.0 g,吐温-80为0.6 g,经超声波乳化后(功率240 W,时间4 min)与明胶2.0 g,阿拉伯胶2.0 g,麦芽糊精10.0 g,蔗糖酯0.5 g,按料液固体质量分数为3.88%的比例与水混合,在进风温度180℃,出风温度105℃,喷雾空气流速为1.5 m3/h,进料速率为6 m L/min的条件下进行喷雾干燥。此条件下,角鲨烯微胶囊包埋率92.3%,颗粒呈球形,粒径在12.0μm左右。喷雾干燥相较于冷冻干燥,所得微胶囊包埋率更高,产品颗粒呈球形,粒径更小,热性能也更加稳定。 相似文献
3.
为提高花色苷的稳定性，拓宽其在功能性产品上的应用，以阿拉伯胶和乳清蛋白为壁材，杜鹃花色苷为芯材，采用响应面法优化锦绣杜鹃花色苷微胶囊的制备工艺，同时运用扫描电子显微镜(SEM),傅里叶红外光谱(FT-IR)仪和热重(TG)分析仪等对花色苷微胶囊进行表征分析。研究结果表明：喷雾干燥法制备锦绣杜鹃花色苷微胶囊的最佳工艺条件为壁芯比4∶1(g/g),进风口温度165℃,进料流量500 mL/h,此条件下，花色苷微胶囊包埋率为(89.28±1.05)%。SEM显示花色苷微胶囊呈较均匀的球状颗粒，粒径为4.0μm,结构紧密，无裂痕，不易黏连。FT-IR分析表明杜鹃花色苷包埋在阿拉伯胶和乳清蛋白形成的薄膜中。TG分析表明花色苷在197.7℃,质量明显下降，而花色苷微胶囊在237.5℃才有明显质量损失。储存稳定性分析表明受光照、温度的影响，杜鹃花色苷微胶囊保留率明显比未包埋的花色苷高。 相似文献
4.
以松仁油微胶囊和牛乳为原料，制备凝固型酸奶。以pH值和感官评价分数为指标，通过单因素试验和正交试验，探究松仁油微胶囊添加方式、微胶囊添加量、白砂糖添加量、发酵时间、发酵温度、稳定剂种类、稳定剂温度以及稳定剂添加量对酸奶品质的影响，并得出最加配方和工艺参数；松仁油微胶囊乳液添加量为0.05 g/mL,CMC添加量为0.15%,白砂糖添加量为8.5%,发酵剂添加量为3%,在38℃下发酵6 h,并在4℃下后熟24 h。以最优工艺条件制作松仁油微胶囊酸奶，进行贮藏稳定性试验，结果发现：添加松仁油微胶囊的酸奶在贮藏期内保持较好的pH值、粘度、持水力、乳酸菌活菌数量。研究制作的松仁油微胶囊不仅能提高酸奶营养价值，对酸奶保存期间的稳定性也有一定的保持作用。 相似文献
5.
6.
7.
采用尿素包合法富集的橡胶籽油ω-3脂肪酸易氧化劣变,为防止产生氧化劣变,以单甘酯:蔗糖酯=1:5为乳化剂,大豆分离蛋白质、酪朊酸钠、麦芽糊精混合物为壁材,采用离心喷雾法制备橡胶籽油ω-3脂肪酸微胶囊,最佳工艺条件为:大豆分离蛋白质、酪朊酸钠和麦芽糊精之比为1:1:1.5,固形物浓度为20%(W/V)的溶液,进料速度20 mL/min,进风温度为160℃,出风温度为80℃。该工艺条件下制备的微胶囊ω-3脂肪酸包埋率达到93.8%,抗氧化性提高4.9倍。 相似文献
8.
《林产工业》2017,(2)
该研究通过将木质素与聚乙二醇按照不同比例混合液化,经过分析计算,选取较优液化产物制备聚氨酯泡沫。然后,通过控制变量法在不同系列下制备木质素聚氨酯泡沫,放置48~72 h固化后再切割成规格为5 cm×5 cm×5 t2m的正方体试件,放置于烘干箱中将其烘干至恒重,检测其相关性能。研究得出:木质素用液化试剂聚乙二醇400按照固液比80:220、催化剂浓H_2SO_41.8%、在液化温度和时间分别为170℃、2 h的条件下液化,得到液化产物的羟值为290 mgKOH/g、黏度为780.2 mPa.s。木质素液化产物与异氰酸酯原料比为1:1.1,发泡剂H_2O、催化剂三乙胺和二月桂酸二丁基锡(质量比1:1)、表面活性剂二甲基硅油分别占总量的4.5%、3%和13%条件下制备出的木质素聚氨酯泡沫效果较优。 相似文献
9.
无色松香季戊四醇酯的稳定化研究 总被引：1，自引：1，他引：0
以无色松香季戊四醇酯的热稳定性、耐候性和储存稳定性为考察指标,对抗氧剂和光稳定剂的稳定化作用进行了研究.结果表明,将0.3%的抗氧剂K-B与0.4%的光稳定剂与紫外线吸收剂LD UV-20添加于无色松香季戊四醇酯中,其热稳定性、耐候性和储存稳定性得到明显改善:在180℃下加热8h,产品颜色小于加纳色号1;距离400W紫外灯40cm下照射15h,产品的增重率为0.213%、颜色为3～4(加纳色号);在40℃下储存30天,其颜色及其中的氢过氧化物浓度基本不变.采用氧化诱导期(OIT)法对试样的抗氧化能力进行了评价,所得结果与上述结论一致. 相似文献
10.
11.
《Scandinavian Journal of Forest Research》2012,27(5):427-435
In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads. 相似文献
12.
《Scandinavian Journal of Forest Research》2012,27(3):206-217
The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage. 相似文献
13.
Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and
also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the
amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter
bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K
was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed
significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week−1 for leaves and from 0.0225 to 0.0633 week−1 for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed
during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly
between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species
provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient
enrichment capacity and slower decomposition rates which would minimize leaching losses.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
14.
Astra Zaluma Lauma Bruna Darta Klavina Natalija Burnevica Kristine Kenigsvalde Andis Lazdins Talis Gaitnieks 《Forest Pathology》2019,49(6)
Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered. 相似文献
15.
《Scandinavian Journal of Forest Research》2012,27(2):118-130
The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions. 相似文献
16.
《Scandinavian Journal of Forest Research》2012,27(1):53-61
This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland. 相似文献
17.
《Scandinavian Journal of Forest Research》2012,27(1):15-27
The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions. 相似文献
18.
本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。 相似文献
19.
Steven Maranz Amadou Niang Antoine Kalinganire Djeneba Konaté Bocary Kaya 《Agroforestry Systems》2008,72(3):231-239
Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional
data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral
contents and B1 and B2 vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising
germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B1 88 mg 100 g−1, B2 187 mg 100 g−1, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal
diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties
to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations. 相似文献
20.
《Wood material science & engineering》2013,8(2):76-84
Abstract Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists. 相似文献