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1.
张琛  王勇  张美文 《动物学杂志》2019,54(3):311-320
东方田鼠(Microtus fortis)是一种栖息于湿地生境的小型哺乳动物,为了解其水生运动适应,作者在实验室内观察和测试了该鼠的游泳行为、皮毛防水性能和长时间游泳能力。结果发现,东方田鼠主要在水面游泳,亦能潜水,游泳姿势是狗刨式,并主要以后肢交替划水提供推进力,速度约为0.37 m/s。在20℃水温条件下,东方田鼠皮毛表现出良好的防水性能,且防水性能与其年龄及体重均存在极显著的负相关关系(P 0.01,R~2=0.805);东方田鼠具有平均约持续5 h以上的长时间游泳能力,且长时间游泳能力与其皮毛防水性能存在极显著的正相关关系(P 0.01,R~2=0.682);上述两项指标性别差异显著。这表明,东方田鼠有较强的水中运动能力和长时间游泳能力,具有水生运动方面的适应性进化,有利于其在沼泽等栖息地的生存。  相似文献   

2.
泥炭藓属(Sphagnum)植物的持水特性在泥炭湿地形成过程中起着重要作用,研究其与土壤营养元素之间的关系有助于地区湿地保护和退化湿地的修复。以贵州麻若平台分布的泥炭沼泽为对象,采用方差分析、相关性分析和冗余分析等方法对沼泽内泥炭藓的生物量、蓄水量、吸水率和土壤营养元素含量等进行研究。结果显示,该区域泥炭藓物种组成主要包括狭叶泥炭藓(Sphagnum cuspidatum Ehrh.)、多纹泥炭藓(Sphagnum multifibrosum X.J.Li&M.Zang)和卵叶泥炭藓(Sphagnum ovatum Hampe.)3种,狭叶泥炭藓为优势种,占泥炭藓总盖度的87.2%。沼泽中泥炭藓的生物量为(0.62 ±0.01)kg/m2,自然蓄水量为(9.42 ±0.45)kg/m2,饱和吸水率达1827.41%±34.56%,说明泥炭藓具有很强的持水能力。RDA分析表明,泥炭藓的生物量、饱和吸水量和饱和吸水率主要受沼泽土壤总钾、总磷、有效磷、有效氮、有效钾的影响,泥炭藓的鲜重、自然蓄水量和自然吸水率受土壤pH和水位的影响较大。泥炭藓的生物量、饱和蓄水量、饱和吸水率与土壤总钾含量呈正相关,与土壤总磷、有效磷、总钾、有效氮、总氮、有机质含量呈负相关,说明土壤总磷、有效磷、有效钾、有效氮、总氮、有机质对沼泽中泥炭藓的持水能力具有抑制作用。  相似文献   

3.
华南典型人工林凋落物的持水特性   总被引:62,自引:0,他引:62       下载免费PDF全文
 对于华南地区的杉木(Cunninghamia lanceolata)林、马尾松(Pinus massoniana)林、湿地松(Pinus elliottii)林、马占相思(Acacia mangium)林和尾叶桉(Eucalyptus urophylla)林的凋落物的储量、持水量、持水率和吸水速率进行了研究。结果表明,杉木林的凋落物的干重(6.5×103 kg·hm-2)最大,其次是马尾松林和马占相思林(5.5×103 kg·hm-2),而湿地松林(4.1×103 kg·hm-2)和尾叶桉林较小(4.0×103 kg·hm-2)。凋落物持水量呈现杉木林>马占相思林>尾叶桉林>马尾松林>湿地松林。各林分凋落物的最大持水量为杉木林17.9×103 kg·hm-2,马占相思林14.8×103 kg·hm-2,尾叶桉林14.0×103 kg·hm-2,马尾松林10.6×103 kg·hm-2,湿地松林9.8×103 kg·hm-2。尾叶桉林、杉木林、马占相思林、湿地松林和马尾松林的凋落物最大持水率分别为351%、274%、269%、235%和191%。凋落物持水量和凋落物持水率随着浸泡时间的增加按照对数方程增加。5种林分中尾叶桉林的凋落物吸水速率在各浸泡时间后居首位,杉木林和马占相思林中等,湿地松林较小,而马尾松林最小,各林分的凋落物的吸水速率随浸泡时间的增长按方程Y=a+b·t-1下降。  相似文献   

4.
Preparation of superabsorbent cellulosic hydrogels   总被引:1,自引:0,他引:1  
In this work, milled softwood (SW) bleached kraft fibers were crosslinked by esterification with poly(vinyl methyl ether-co-maleic acid) (PVMEMA) and polyethylene glycol (PEG). The effects of fiber length, crosslinking reaction time, and dosage of PVMEMA on water absorption and retention value (WAARV) for the crosslinked fibers were determined. The results show that as the softwood fiber length is mechanically decreased from 2.41 to 0.50 mm and employing a weight ratio of fiber to polymers equivalent to 1.00:1.28 the WAARV increased from 86.50 to 189.20 g/g. Analysis of the crosslinked fibers by SEM and light microscope indicated that the polymers and fibers form a crosslinked fibrous matrix. FT-IR spectroscopy was employed to detect the ester linkage between PVMEMA and PEG/SW kraft pulp fibers. The results suggested that the ester crosslinked pulps exhibit excellent water absorbent properties and have the potential of utilizing milled bleached SW kraft fibers, such as refiner dust or pulp fines, for novel water absorbent applications.  相似文献   

5.
Larvae of the mealworm beetle Tenebrio molitor, are able to absorb water vapour from subsaturated air, but adults cannot. This functional difference is paralleled by structural differences in the cryptonephridial rectal complex, the site of vapour absorption in the larva. Very distinctive differences occur in the rectal pad epithelium and these are reported in detail for the first time. The cells of the larval rectal pad are very closely apposed, forming a structural, and presumably functional, unit, whereas the cells of the adult rectal pad are more clearly separate. Intracellular organization also shows clear differences. These differences indicate that the rectal epithelium may play a more important role in vapour absorption than recently ascribed to it. Other, less striking, differences in the cryptonephric Malpighian tubules and perinephric membrane as previously recorded have largely been confirmed. Morphometric analysis suggests that diffusion alone could account for the observed absorption of water vapour across the larval system from rectal lumen to the lumen of the cryptonephric tubules, but this does not rule out the possibility that other transporting mechanisms are also involved. Radial diffusion and antero-posterior gradients may be facilitated by the predominently radial and circumferential arrangement of the rectal pad cells and the surrounding cryptonephric tubules. Reinvestigation of the isolating perinephric membrane and its insertion onto the rectal cuticle supports the conclusions that insertion occurs only posteriorly. The model incorporating anterior as well as posterior insertion does not apply. The membrane posteriorly encloses a single perirectal space between rectum and tubules and in this region no perinephric or peritubular space is found between inner and outer regions of the membrane. This is the region where maximal gradients occur across the system.  相似文献   

6.
7.
Summary Eel atrial natriuretic peptide inhibited the serosa-negative transepithelial potential difference and short-circuit current, accompanied by a decrease in NaCl and water absorption across the seawater eel intestine. Similar effects were obtained after treatment with N-terminally truncated eel atrial natriuretic peptide (5–27), indicating that N-terminal amino acids are not essential for the action of eel atrial natriuretic peptide. Although mammalian atrial natriuretic peptides also inhibited the short-circuit current, a 100-fold higher concentration was reuired to obtain the same effect as with eel atrial natriuretic peptide, indicating that eel atrial natriuretic peptide is 100 times as potent in eel intestine as the mammalian atrial natriuretic peptides. Similarly, in mammalian atrial natriuretic peptide, the four N-terminal amino acids had no significant effects. However, when the C-terminal tyrosine was removed, the potency of rat atrial natriuretic peptide was lowered. Compared with the effects of acetylcholine, serotonin and histamine, eel atrial natriuretic peptide was the most potent inhibitor, with 100% inhibition at 10-7 M; 50% inhibition was obtained at 10-2 M in acetylcholine, and 30% inhibition in serotonin (10-5 M) and histamine (10-3 M). These inhibitory effects of eel atrial natriuretic peptide were not diminished even in the presence of tetradoxin, and were mimicked by 8-bromoguanosine 3,5-cyclic monophosphate. Based on these results, structure-activity relationships of eel atrial natriuretic peptide and a possible mechanism of action of eel atrial natriuretic peptide are discussed.Abbreviations 8BrcGMP 8-bromoguanosine 3,5-cyclic monophosphate - eANP eel atrial natriuretic peptide - hANP human atrial natriuretic peptide - 5-HT 5-hydroxytryptamine creatine sulphate - I sc short-circuit current - PD transepithelial potential difference - rANP rat atrial natriuretic peptide - R t tissue resistance - TTX tetrodotoxin  相似文献   

8.
三种松树的生理生态学特性研究   总被引:13,自引:1,他引:12  
测定南亚热带丘陵地马尾松、湿地松和加勒比松光合速率、蒸腾速率、日同化量和水分利用效率的变化.结果表明,3种松树光合速率和蒸腾速率都具有明显的日变化和季节变化,夏季的光合速率和蒸腾速率最高,冬季最低;加勒比松的平均日同化量为9.34g·kg-1、平均水分利用效率为159.75μmolCO2·g-1H2O,高于其它树种;湿地松最低.加勒比松是很好的引种树种,更适合在当地推广  相似文献   

9.
本研究选取贵州都匀市ë尖镇螺蛳壳风景区沼泽湿地的6种泥炭藓属(Sphagnum)植物,分别测量其主茎粗、株高,计数侧枝数和分枝数,并计算其饱和吸水率、外吸水率、内吸水率、透明细胞面积占比、侧枝密度等指标。结果显示:(1)6种泥炭藓饱和吸水率大小依次为狭叶泥炭藓(S.cuspidatum Ehrh)(2518.99%)>泥炭藓密枝亚种(S.palustre L.ssp.pseudocymbifolium (C.Müll.) A.Eddy)(2351.87%)>泥炭藓原亚种(S.palustre L.ssp.palustre)(2122.88%)>小孔泥炭藓(S.microporum Warnst.ex Card)(1936.79%)>拟宽叶泥炭藓(S.platyphylloides Warnst)(1684.88%)>卵叶泥炭藓(S.ovatum Hampe)(1660.64%);(2)6种泥炭藓的内吸水率均高于外吸水率;(3)透明细胞面积占比与吸水率(饱和、内、外)呈极显著正相关(P < 0.01);侧枝密度与内吸水率呈极显著正相关(P < 0.01),与饱和吸水率呈显著正相关(P < 0.05)。本文所测指标中,透明细胞面积占比和侧枝密度对泥炭藓持水能力的影响最大。  相似文献   

10.
多效唑在土壤中的行为研究   总被引:1,自引:0,他引:1  
本文利用示踪技术研究多效唑在3种土壤中的行为。土壤理化性质对多效唑在土壤中的纵向移动和横向扩散有影响。多效唑在土壤中的纵向移动性较大,且随时间的推移纵向移动性减小.多数唑易被土壤吸附,但仍有部分易随雨水横向扩散和纵向移动。土壤对多效唑的吸附量随浓度增加而提高,在一定浓度范围内,浓度对吸附率的影响不大。  相似文献   

11.
Konjac glucomannan was extruded and subsequently ground under four conditions denoted: KGM1 (33% solids, 90 °C), KGM2 (24% solids, 90 °C), KGM3 (24% solids, 90 °C, die restriction), and KGM4 (24% solids, 110 °C). SEM and particle size analysis showed that extruded KGM had slightly larger and rougher particles. The water absorption index was decreased to 47.92-128.80, as compared to 153.64 for the control (KGMC). The crystallinity index increased to 2.97 and 3.42 for KGM3 and KGM4 samples, as compared to 1.72 for the control. Zero-shear viscosity of 0.5% solutions decreased to 0.36-3.01 Pa s. All samples were shear-thinning and data were best fitted by the Cross model. Based on capillary viscometry, molecular weights were decreased to 2.7 × 105-9.9 × 105, as compared to 1.2 × 106 for the control. In most cases, properties were most altered by higher temperature and shear, and to a lesser extent by lower solids in the feed.  相似文献   

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