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黄河首曲高寒草甸退化草地(黑土滩)恢复重建优良适宜牧草筛选试验 总被引：1，自引：0，他引：1
筛选优良适宜的牧草品种是黄河首曲高寒草地退化草地生态恢复与重建、"黑土滩"治理的基础和关键环节。引种筛选适合当地生态环境的、具有快速恢复高寒草地退化草地功能、有较高的放牧利用及生态价值的优良牧草品种,是高寒地区退化草地生态恢复与重建的关键环节,也是草地畜牧业可持续发展的重要物质基础。结果:参试的6种牧草出苗排序是:无芒雀麦、老芒麦、垂穗披碱草、冷地早熟禾、草地早熟禾、中华羊茅;参试的6种牧草越冬率高于50%的冷地早熟禾、垂穗披碱草、草地早熟禾和中华羊茅在次年能完成生育期,无芒雀麦和老芒麦第二年不能完成生殖生长,均处于抽穗期和开花期;通过综合评价,两种早熟禾植株低矮,耐践踏,而且地下茎发达,能固结表土,有保持水土,防止雨水冲刷的作用,可增加植被盖度,减少风蚀和水蚀的危害。垂穗披碱草、老芒麦、中华羊茅根系较发达,抗旱、耐寒性强,种子产量较高,可以用作种子扩繁生产,为"黑土滩"治理和草地恢复重建提供种子储备;参试草种中首选两种早熟禾,其次是垂穗披碱草,第三是老芒麦和中华羊茅,最后是无芒雀麦。 相似文献
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不同植被重建管理方式对沙质草地土壤及植被性质的影响 总被引：2，自引：0，他引：2
以陕北横山县雷龙湾乡恢复15年的退化沙质草地为研究对象,对未封育自然恢复、封育自然恢复、未封育人工恢复和封育人工恢复4种管理方式对植被和土壤性质的影响及二者的相关性进行了研究,以期为退化沙质草地筛选科学的植被恢复模式选择提供科学依据.结果表明:与流动沙地对照组相比较,经过15年的植被恢复4种管理方式均可不同程度的改善退化草地土壤及植被性质,地表植被高度、盖度和生物量分别提高0.12~1.03 m,12.70%~53.18%和7.27~29.08 g·m-2,土壤容重降低0.12~0.27 g·cm-3,土壤总孔隙度提高6.80%~17.01%,有机质、阳离子交换量、全氮及速效养分含量也显著提高.封育管理方式下植被与土壤的恢复效果优于未封育方式,人工植被恢复优于自然植被恢复,采取封育与人工植被恢复相结合的管理方式,严重退化沙质草地在植被恢复过程中植被与土壤特征形成了相互作用、相互影响的协调关系.为了促进农牧交错带退化沙质草地生态恢复,研究区应该采取封育与人工恢复相结合的植被恢复管理方式. 相似文献
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在党中央、国务院关于“再造一个风景秀丽的西北”的号召下,全国各地纷纷掀起植树种草的热潮,霎时种子价扬,苗木紧缺,被一度冷落的草产业又“火”了起来。但是笔者窥豹一斑,发现热潮面前有许多盲动性。一是认识不足,认为种草很简单,种子撒进地里就完事。其实种草是一项十分精细的生物工程,比种树、甚至于种庄稼还要要求高,牧草种子一般籽粒细小,芽苗纤弱,因此对土壤耕作层的细度、温度、湿度以及耕作深度,镇压紧实度都有严格的要求,有些牧草种子硬实程度高,播种前还要去芒、浸泡或擦破种皮等技术处理,技术操作性很强,一旦哪一个环节不按技术规程操作,种草就很容易失败。二是重视不够。主要是领导重视不够。有些领导还没有把种草从改善生态的角度去考虑,认为种草只不过是发展畜牧业,这是业务部门的事。工作只是停留在一般号召上,缺乏具体的计划指导,缺乏应有的行政推动。总体来讲,关心的少,支持的少,管理的少。其实草场是自然界中最大的基因库、能源库、蓄水库、涵氧库,一种草的灭绝就要造成10－30种与之相依的生物的随之消失。我们讲造福子孙后代,植树种草才是真正的造福子孙后代。三是植树与种草的关系处理的不当。重树轻草思想严重。认为栽树一棵是一棵,植树似乎绿的快。其实不然,树和草的维活需水量具有显著差异,一般牧草降水量在350毫米以上就能生长并形成商品量,而林木降水量在450毫米以上才能生长并形成商品量。因此,干旱缺水地区恢复植被、改善生态,应该首先选择种草,而不是植树,原因是牧草需水量小,比林木更容易成活。通过种草恢复植被,使这些土壤有一定的蓄水力和涵氧能力后再植树,走草灌乔的种植模式效果较好。如果不遵循这个规律,不顾种植条件,一味植树,哪怕是“年年植树,年年死,只有数字,没有林子”,一夜见绿洲,欲速则不达。那么,如何才能种好草,当前种草该注意些什么？ 相似文献
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赖草是科尔沁草原区沙质土壤生境广泛生长的优良禾草,是典型的无性系植物.在内蒙古科尔沁草原区,赖草的分蘖节和根茎均可存活4个年度.在8月中旬,经历了11～12年植被恢复的储灰池中,赖草种群的根茎是由4个龄级组成, 4～5年植被恢复的储灰池则由3个龄级组成.2个样地赖草无性系种群的分蘖株均由2个龄级组成,均为增长型的年龄结构,恢复的时间越短,其增长型结构就越明显. 相似文献
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国内生态恢复研究进展 总被引：10，自引：1，他引：9
本文介绍了生态恢复的研究进展,从生态恢复的定义、退化生态系统的指标等方面进行阐述,重点对国内在恢复生态学方面的进展做了介绍。对当前的人工草地、草地农业的研究情况做了一些概述。 相似文献
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As it is for mammalian species, growth hormone (GH) is indispensable for normal growth and development of avian species. In contrast to mammals, exogenous GH administration has little, if any, potential for improving the growth rate and feed efficiency of rapidly growing broilers; it is more likely to do so in older birds. This is at least partly because of age-related changes in tissue GH-binding activity and GH-receptor mRNA expression. The effects of GH on lipid deposition depends on the age of the bird and pattern of GH administration. Pulsatile, but not continuous, GH administration to older broilers seems to reduce fat deposition. As in rats, the bioactivity of GH might also depend on the pulse-induced cyclicity in GH receptors and GH-binding proteins. In chickens, GH is also a very potent lipolytic hormone, but seems to have no diabetogenic effect, which is reported in mammalian species. Both insulin-like growth factors have apparently no growth-promoting effects in normal growing broilers, but seem to have opposite effects on fat deposition. In contrast to GH, both insulin-like growth factors have a marked hypoglycemic effect. Whether all these effects are direct effects, or are mediated by secondary mechanisms, awaits further investigations. 相似文献
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反刍动物瘤胃碳水化合物发酵研究进展 总被引：1，自引：0，他引：1
碳水化合物是反刍动物营养的一个重要组成部分，碳水化合物在反刍动物瘤胃的发酵又是其营养吸收利用的一个重要过程。本文根据国内外研究成果，全面综述了碳水化合物的分类及影响反刍动物瘤胃碳水化合物发酵的三方面因素，揭示了反刍动物对碳水化合物的吸收规律，为我国反刍动物饲养提供指导。 相似文献
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生殖周期小鼠子宫内膜上皮淋巴细胞的数量变化 总被引：1，自引：0，他引：1
应用甲苯胺蓝染色方法，观察了发情周期、妊娠期和分娩后小鼠子宫粘膜上皮内淋巴细胞的消长情况。与间情期相比，上皮内淋巴细胞的数量在发情前期减少，而发情期和发情后期又增加。妊娠 １ ｄ 数量较少，１４ ｄ 开始回升，１８ ｄ 的数量超过间情期。分娩后 １ ｄ 突然升高，随后又逐渐恢复。这些结果提示，上皮内淋巴细胞可能参与子宫粘膜免疫。 相似文献
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Up to now there has been only a method available for testing the antihaemorrhagic activity of plant extracts, in which chicken embryos had to be transferred to a special container on the fifth day of incubation. Furthermore, the test could not be conducted on the extraembryonal circulatory system until two days later. In the test method described here the embryos remain inside the egg. After removal of the eggshell through the air cell and removal of the inner shell membrane, direct access to the extraembryonal circulatory system is possible, minimising external influences on the test system. This represents a dramatic simplification in technique and permits testing already on the fourth day of incubation. The application of this method to determine the antihaemorrhagic properties of samples has the advantage of permitting the simple and quick production of haemorrhages by snake venom on the yolk sac circulatory system. 相似文献
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Survival, egg production and egg viability of fleas allowed to feed on eight flea-allergic and six flea-naive cats were compared. Fifty fleas, in feeding cages or free roaming, were allowed to feed on the cats. Flea-allergic cats removed significantly more free-roaming fleas than did flea-naive cats. Female fleas produced fewer eggs on flea-allergic cats than on flea-naive cats regardless of feeding method. There was no significant difference in egg viability between the two groups. The data suggest that flea-allergic cats efficiently removed fleas by grooming and that they also produce unknown factor(s) that affect the fecundity of fleas. 相似文献
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Gnotobiotical one-day-old piglets were infected with 100,000 Isospora suis coccidia oocysts, and were immediately killed. In piglets killed on the 3rd to 11th day after infection (DAI), the morphometric analysis of alkaline phosphatase activity was performed in the area of the microvillus zone of small intestine. In the control 2-7 days old animals, the small intestine was not equally supplied with alkaline phosphatase. In duodenum the activity reached 88.37 per cent of the active length of absorbent surface (% LAac), in the middle jejunum 95.98 per cent LAac, in the dorsal jejunum 78.63% LAac and the ileum 90.55 % LAac. The width of the active area was more balanced and ranged from 5.003 microM in the ileum to 6.129 microM in the dorsal jejunum. In infected gnotobiotical piglets the lowest activity was found out on the 3rd to 4th DAI, with a greater decline on the 9th day after infection. The range from 25.99 to 40.50 per cent LAac with minimum in the duodenum and maximum in the ileum was observed on the 3rd DAI. In the middle and dorsal ileum the activity was nearly equal (28.34 and 27.69 per cent LAac). nI the dorsal jejunum a moderate increasing was up to 47.13% LAac on the 4th DAI, with the exception of the ileum, where the activity of alkaline phosphatase decreased to 24.96% LAac. On the 9th DAI the activity of alkaline phosphatase was nearly equal in the whole small intestine (from 55.70 to 60.01% LAac) with the maximum in the middle jejunum. In the width of the reaction product a direct dependence on the total activity of alkaline phosphatase was evident only in the segment of the middle and dorsal jejunum and ileum, but merely on the period of the 3rd to 4th DAI. The lowest values were measured in the middle jejunum (0.982 micron on the 3rd DAI and 0.709 micron on the 4th DAI). No dependence was observed between the total activity and the reaction product in the middle jejunum (0.982 micron on the 3rd DAI and 0.709 micron on the 4th DAI), there was no general stabilisation of the activity of alkaline phosphatase. 相似文献
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抗生素替代品对泰和乌骨鸡小肠α-淀粉酶和胰蛋白酶活性的影响 总被引：1，自引：0，他引：1
为提高泰和乌骨鸡和鸡药用价值、滋补作用及生产性能 ,研究了益生素、寡果糖、糖萜素和中草药制剂等抗生素替代品对泰和乌骨鸡十二指肠内容物中a -淀粉酶和胰蛋白酶的活性影响。结果表明 ,① 5周龄时 ,与对照组相比 ,a -淀粉酶活性 :寡果糖组和糖萜素组均呈显著提高 (P <0 0 5 ) ,益生素组和中草药组有一定程度的提高 ,但无显著差异 ;胰蛋白酶活性 :有显著提高 (P <0 0 5 )的是益生素组、寡果糖组和糖萜素组 ,中草药组有提高的趋势 ,但差异不显著 (P >0 0 5 )。② 10周龄时 ,a -淀粉酶和胰蛋白酶活性呈显著提高 (P <0 0 5 )的有寡果糖组、糖萜素组和中草药组 ,益生素组比对照组有提高的趋势但差异不显著 (P >0 0 5 )。 相似文献
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J.M. Winterbottom 《African Zoology》2013,48(1):83-90
Many white-faced whistling ducks (Dendrocygna viduata) have responded to European colonization by overwintering on irrigation and stock-watering ponds in the semi-arid interior of South Africa. I studied the body condition, diet, behaviour and moult intensity of whitefaced whistling ducks prior to departure for breeding areas during spring 1995. Other than higher protein levels in immature males than immature females, there were no sexual differences in body mass or levels of lipid, protein, or ash in adults or immatures. Adults were heavier than immatures and had higher levels of ash. There were no sex- or age-related differences in the proportion of individual food items consumed, 96.6% of which was maize. By foraging on neighbouring agricultural fields, birds were able to spend large portions (80%) of the day/night in comfort-related activities (preen, loaf, sleep) and little time foraging (8.8%) while on ponds. There were no sex- or age-related differences in overall moult intensity score or intensity of moult in 20 feather areas. With exception of primaries and secondaries, birds were moulting moderately to heavily in all feather regions. Agricultural ponds permit whitefaced whistling ducks to overwinter close to breeding areas, while the high availability and energy content of maize enables them to attain higher spring fat levels than birds that overwinter on traditional sites closer to the coast. Intensive agriculture has probably contributed to the population increase and range expansion of white-faced whistling ducks in South Africa. 相似文献
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Salvetti NR Ricci N Dallard BE Lorente JA Iguzquiza I Ortega HH 《Anatomia, histologia, embryologia》2000,29(3):129-134
Most studies on the biochemistry and structure of the corpus luteum have focused on elucidating the processes of progesterone synthesis and release. In the present work, the histochemical composition of the corpus luteum of the rat was evaluated using lectinhistochemistry on rats at the end of pregnancy (days 18-23). We also analysed the morphology of the luteal cells, to characterize the changes attributable to regression in this organ. Seven biotinylated lectins were used (CON-A, WGA, DBA, SBA, PNA, RCA and UEA-I) following pre-set protocols (ABC method). The average diameter and area of the cells and their nuclei were measured. High reactivity of the luteal cells was observed with CON-A and a lower reactivity with WGA. The capillary endothelium gave positive reactivity with WGA and to a certain extent with SBA, PNA and RCA. Vesicular structures were intensely stained with DBA, and were more abundant in sections from animals with more advanced pregnancy, which could be attributable to cellular debris, on the basis of their morphologic characteristics. There were no significant differences among the cytometric variables analysed in comparisons of the values corresponding to the different days of gestation. These observations, together with previous research, suggest that, on the day of delivery, the corpus luteum of the rat is in the very early stages of structural regression, with no changes at the morphological level, but with changes at the molecular level. 相似文献