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1.
两种草坪型高羊茅光合生理生态机理的研究 总被引：8，自引：0，他引：8
在自然状态下利用Licor-6400便携式光合测定系统测定了两种草坪型高羊茅(凌志和交战Ⅱ)在南京夏季光合生理生态参数的日变化。结果表明，两者在各光合生理生态参数的日变化中存在明显的差异。凌志叶片净光合速率的日变化呈典型的双峰曲线，有明显的光合“午睡”现象。分析表明，这种光合“午睡”属于非气孔限制。与交战Ⅱ相比，凌志在午后表现出较高的净光合速率和水分利用效率以及较低的蒸腾速率，表明凌志比交战Ⅱ高羊茅更能适应炎热夏季。 相似文献
2.
在昆明市利用Ci-310便携式光合测定仪测定了纳罗克非洲狗尾草（Setaria sphacelata stapf cv.Narok）种子田夏季光合生理参数的日变化.对大气温度、CO2浓度、相对湿度、植物气孔导度、胞间CO2浓度、蒸腾速率、瞬时水分利用率、光合有效辐射、净光合速率等参数进行分析,结果表明：纳罗克非洲狗尾草光合生理特性受环境影响呈规律性变化,光合速率、光合有效辐射、气孔导度和蒸腾速率的日变化呈双峰曲线,存在“午睡”现象.非气孔限制为引起光合“午睡”的主要原因,其中净光合速率降低为叶肉光合活性下降所致. 相似文献
3.
日光辐射对老芒麦再生草光合特性的影响 总被引：10，自引：1，他引：9
采用CI 310便携式光合测定仪,分别在晴天和阴天对老芒麦再生草的净光合速率、光合有效辐射及蒸腾速率等相关生理生态指标进行测定。结果表明,在晴天和阴天不同日光辐射下,再生草净光合速率的日变化曲线呈双峰型,晴天有明显光合"午休"现象。相关分析结果表明,无论晴天或阴天,光合有效辐射和蒸腾速率与净光合速率相关性一致,其主导因子与净光合速率相关性排序为:光合有效辐射>蒸腾速率>叶片温度。其中可控因子是蒸腾速率,而蒸腾速率则与净光合速率呈正相关,因此保持老芒麦再生草旺盛的蒸腾速率是提高净光合速率的有效途径。 相似文献
4.
桑树春季光合速率变化及其影响因子的研究 总被引：3，自引：0，他引：3
对桑树品种育71-1春季的光合特性的研究发现:净光合速率的日变化呈双峰曲线,峰值分别是在上午9:30和下午的3:30;净光合速率的月变化规律与光合有效辐射的变化规律几乎一致,说明光合有效辐射对净光合速率是直接作用因子;在生理生态因子对桑树光合变化的影响中,叶温既是生理的主导因子,又是生态的主导因子,在栽培上若能有效地调控叶温,将对桑树光合作用产生积极的影响。对桑树品种育71-1春季的光合特性的研究发现:净光合速率的日变化呈双峰曲线,峰值分别是在上午9:30和下午的3:30;净光合速率的月变化规律与光合有效辐射的变化规律几乎一致,说明光合有效辐射对净光合速率是直接作用因子;在生理生态因子对桑树光合变化的影响中,叶温既是生理的主导因子,又是生态的主导因子,在栽培上若能有效地调控叶温,将对桑树光合作用产生积极的影响。 相似文献
5.
北京地区公农1号紫花苜蓿叶片光合作用日变化特征 总被引：6，自引：4，他引：2
在自然状态下,利用Licor-6400便携式光合测定系统观测了公农1号紫花苜蓿Medicago sativa在北京地区的光合作用日变化规律.结果表明:公农1号叶片的净光合速率日变化呈典型双峰曲线,表现出明显的光合"午睡"现象,光合效率午间明显降低;蒸腾速率日变化趋势与净光合速率相似,胞间CO2浓度的日进程基本与净光合速率相反;气孔导度日变化与净光合速率日变化相似但并不完全同步,两者最大值出现的时间相同,但最低值出现的时间气孔导度较净光合速率晚约2h.经分析,公农1号紫花苜蓿表现出的光合"午睡"现象属于非气孔限制. 相似文献
6.
杂花苜蓿叶片光合生理生态特性 总被引：19，自引：6，他引：13
研究甘农1号杂花苜蓿(Medicago varia.cv.Gannong No.1)叶片光合生理生态特性。结果表明:不同生育期苜蓿叶片光合生理生态日变化动态各异;光合速率在5月和6月呈双峰型,有光合“午休”现象,在7月呈单峰型;蒸腾速率和气孔导度在各时期均呈双峰型;回归分析和相关分析结果表明,不同时期对叶片的净光合速率和蒸腾速率起主导作用的环境因子有所差异,同一环境因子在不同时间对净光合速率和蒸腾速率的影响程度各异;温度是光合作用影响最主要的环境因子;受环境因子控制最显著的生理特征是叶片的蒸腾速度。 相似文献
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3种禾本科牧草光合特性研究 总被引：4，自引：2，他引：2
在田间测定了生长2年的野大麦,直穗鹅观草和垂穗披碱草的光合特性,并采用相关系数分析了影响3种禾本科牧草光合特性日变化的主要因子。结果表明：（1）3种禾本科牧草的净光合速率日变化均呈双峰型,野大麦的第1峰值出现在8：00,直穗鹅观草和垂穗披碱草的第1峰值出现在10：00,野大麦的第2峰值出现在14：00,直穗鹅观草和垂穗披碱草的第2峰值出现在16：00;（2）野大麦在12：00有明显的光合“午休”现象,直穗鹅观草和垂穗披碱草的光合“午休”现象出现在13：00;（3）3种禾本科牧草的净光合速率日变化的主要影响因子不同,影响野大麦和垂穗披碱草的净光合速率日变化的主要因子是气孔导度,而影响直穗鹅观草净光合速率日变化的主要因子是胞间CO2浓度。 相似文献
9.
干旱胁迫下本氏针茅光合特性和水分利用效率日动态研究 总被引：4，自引：1，他引：3
采用盆栽和人工控制土壤水分的方法,使用Li-6400便携式光合测定系统观测本氏针茅(Stipa bungeana)光合生理生态特征的日变化.结果表明:在不同土壤水分状况下,本氏针茅净光合速率日变化曲线均呈"双峰"型,并有不同程度的"午休"现象,且上午的净光合速率明显高于下午,随着土壤水分的升高而增加;蒸腾速率日变化曲线也呈"双峰"型,表现为较高土壤水分处理针茅具有较高的蒸腾速率;气孔导度受水分和光热胁迫的影响,日变化曲线呈凹型;胞间CO2浓度受空气CO2浓度和气孔导度的双重影响,呈现早晚高,正午低的日变化进程;水分利用效率最高值出现在上午较早的时段,随着土壤水分的增加,水分利用效率却降低. 相似文献
10.
用便携光合系统测定仪对美国无芒雀麦和肇东苜蓿叶片动态光合生理特性进行了研究,结果表明:5月苜蓿单播与混播净光合速率日变化幅度不大,无芒雀麦净光合速率呈双峰型;6月2种牧草的光合速率日动态曲线均为双峰型,有明显的午休现象,而7月为单峰型,没有午休现象。2种牧草单播与混播蒸腾速率变化趋势相似,苜蓿盛花期、无芒雀麦抽穗期的光合速率、蒸腾速率和水分利用效率单混播均最高,苜蓿和无芒雀麦混播叶片光合速率、水分利用效率略高于单播叶片,但在光合午休期间差异不明显。 相似文献
11.
Rassnick KM Gieger TL Williams LE Ruslander DM Northrup NC Kristal O Myers NC Moore AS 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2001,15(3):196-199
1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks. 相似文献
12.
Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects 总被引：1，自引：0，他引：1
Johansson AM Gardner SY Levine JF Papich MG LaFevers DH Fuquay LR Reagan VH Atkins CE 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2003,17(6):887-895
Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses. 相似文献
13.
Waruiru RM Thamsborg SM Nansen P Kyvsgaard NC Bogh HO Munyua WK Gathuma JM 《Tropical animal health and production》2001,33(3):173-187
The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round. 相似文献
14.
The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host. 相似文献
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16.
Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ 
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下载免费PDF全文 S. Pashaei T. Ghoorchi A. Yamchi 《Journal of animal physiology and animal nutrition》2016,100(2):211-216
An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed. 相似文献
17.
Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb
albumin
- ALT
alanine aminotransferase
- AST
aspartate aminotransferase
- BUN
blood urea nitrogen
- Chol
cholesterol
- Glob
globulin
- -GT
-glutamyl transpeptidase
- IP
inorganic phosphorus
- TP
total protein 相似文献
18.
A knowledge of the microbiological status of milk and of the different structures in the mammary glands has great importance
in elucidating the pathogenesis of mammary gland infections. The objective of this study was to evaluate the microbiological
status of various structures in the mammary glands from naturally infected dairy cows following slaughter. A total of 94 samples
of milk, 184 samples of mammary parenchyma, 168 samples of gland cisterns, and 168 samples of teat cisterns were collected
for microbiological examination. Microorganisms were detected in 59.9% of all samples, 67.0% of the milk samples, 70.1% of
the mammary parenchymas, 55.9% of the gland cisterns and 48.8% of the teat cistern samples. When all samples were considered,
coagulase-negative Staphylococcus were the most prevalent (35.7%) followed by coagulase-positive Staphylococcus (12.2%), Corynebacterium bovis (2.4%), Prototheca sp. (1.9%), and Streptococcus dysgalactiae (1.5%). There was a significantly higher occurrence of microorganisms in the milk and mammary parenchyma compared to the
gland cisterns and teat cisterns.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
Four grass plots were sequentially contaminated with goat faeces containing known numbers of unembryonated eggs of predominantly Haemonchus contortus and Trichostrongylus spp. between October 1982 and April 1983. Four other plots were similarly contaminated with sheep faeces between February and May 1987. An additional plot was repeatedly contaminated with sheep faeces from February to April 1987. Populations of free-living stages in faeces and of infective larvae (L3) in the herbage were subsequently monitored until the end of April and June of 1983 and 1987 respectively. During February and May 1987 two control cultures of sheep faeces were incubated in the laboratory at 25°C–30°C and at a constant temperature of 50°C and the free-living development was also monitored. L3 developed very readily in the faeces cultured at 25°C–30°C and in those spread on a grass plot in October, at the end of the wet season, but developed less on the plot contaminated in May at the start of the wet season. Worm eggs in faeces deposited on plots during the hot dry season (December to April) or incubated at 50°C died and disintegrated after 24–48 h exposure to the high environmental temperatures. The results indicate that it is unlikely that gastrointestinal nematodes of sheep and goats can develop or survive on open pasture during the dry season in the Nigerian derived savanna zone. 相似文献
20.
Acute phase proteins in dogs naturally infected with the Giant Kidney Worm (Dioctophyme renale) 下载免费PDF全文
下载免费PDF全文 Elizabeth M. S. Schmidt Mads Kjelgaard‐Hansen Funmilola Thomas Asta Tvarijonaviciute José J. Cerón P. David Eckersall 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》2016,45(4):657-664