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排序方式: 共有175条查询结果,搜索用时 15 毫秒
41.
Grave C 《Science (New York, N.Y.)》1905,21(541):732-737
42.
KariTuomela 《林业研究》1997,(1)
INTRODUCTIONEllca{opIusmicrolhccaF.MucII.(coolibal1)l1asawidegeographicrangemainly``-itl1intl1caridandscl11i-aridzonesofAustralia(Bola11dctal.l984).Tl1erangcoflatitlldeisl4-33Su-itl1analtitudinalrangeofJustabovesealeveIto7oom.Tl1crcislcssvariationincli-ma… 相似文献
43.
Yuri Gerasimov Victor Senkin Kari Väätäinen 《European Journal of Forest Research》2012,131(3):647-654
A field-based study was carried out to broaden our knowledge of fully mechanized cut-to-length harvesting productivity in
naturally grown forests in the northern European part of Russia (NEPR). The recorded data comprised 38 midsized single-grip
harvesters (JD 1270D) in clear-cutting operations in the Karelia, Komi, Vologda, Leningrad, Tver, and Kirov regions in NEPR,
4.3 million felled trees, and 1.4 million m3 u.b. (under bark) of processed timber. Harvesting operations were conducted in forest stands composed of spruce (48% on average),
pine (19%), birch (22%), and aspen (11%), with an average stem volume 0.31 m3 u.b. The cut-to-length harvesters produced from 4.3 to 14.9 m3 u.b./productive machine hour (PMH) and 16.0–49.5 m3 u.b./stem processing machine hour (S
proc
MH). A machine evaluation analysis and a regression analysis were used to formulate models for predicting cutting productivity
of modern single-grip harvester. The regression models were developed to estimate the productivity of the harvesters in the
regions taking into account two significant factors influencing the productivity: the stem volume and tree species of the
felled trees. Productivity/cubic meter u.b. of processed timber/PMH was calculated according to stem volume and tree species distributions in most forest-covered NEPR regions. Further research
is suggested to improve the developed productivity models and to allow prediction of system performance over a broad range
of stand and site conditions. 相似文献
44.
不同含量引诱剂对落叶松八齿小蠹及其天敌红胸郭公虫的引诱(英文) 总被引:1,自引:0,他引:1
在内蒙古阿尔山的田间诱捕试验中,落叶松八齿小蠹引诱剂1共诱集到16头落叶松八齿小蠹和1319头天敌红胸郭公虫,而落叶松八齿小蠹引诱剂2诱集到24104头落叶松八齿小蠹和776头红胸郭公虫。室内的触角电位试验结果表明:落叶松八齿小蠹对引诱剂2的触角反应(雌虫2.139mV±0.678mV,雄虫2.169mV±0.473mV)大于引诱剂1(雌虫0.440mV±0.232mV,雄虫0.297mV±0.142mV),对引诱剂1的反应值和对照差不多;而红胸郭公虫对引诱剂1的触角反应(雌虫4.618mV±1.106mV,雄虫4.534mV±1.087mV)明显大于引诱剂2(雌虫2.209mV±0.680mV,雄虫1.953mV±0.601mV),对引诱剂2也有一定的反应值。触角电位试验与田间诱捕试验结果相符合。GC-MS分析结果表明:引诱剂1的主要成分为3.06%的cis-geraniol,1.98%的Ipsenol,80.36%的(S)-cis-verbenol和1.03%的1-verbenone;结合卖方公司提供的数据,引诱剂1的主要成分为4.78%的2-methyl-3-buten-2-ol,63.71%的Ipsenol(纯度为96.9%),1.46%的Cedrene和22.42%的Isocaryophillene。结合以上数据分析得出:不同成分引诱剂对落叶松八齿小蠹及天敌红胸郭公虫引诱能力显著不同,Ipsenol对诱集落叶松八齿小蠹起重要作用,而(S)-cis-verbenol则对诱集天敌红胸郭公虫起重要作用。 相似文献
45.
46.
McClanahan SL Malone ED Anderson KL 《The Canadian veterinary journal. La revue veterinaire canadienne》2005,46(3):247-249
A 6-month-old female alpaca was presented for stranguria. Based on the history, physical examination findings, and radiographic studies, the alpaca was diagnosed with bladder outlet obstruction, secondary to pelvic displacement of the bladder, a condition previously unreported in camelids. Cystopexy was performed and the alpaca recovered unremarkably. 相似文献
47.
Two experiments were conducted to investigate the effects of 1,25(OH)2D3 to stimulate Na+-dependent phosphate uptake in Caco-2 cells, and the effects of dietary vitamin D supplementation to vitamin D-deficient nursery pigs on Na+-dependent nutrient uptake and mRNA expression of NaPi-IIb cotransporter and calbindin D9k in the jejunum. In Exp. 1, 250,000 Caco-2 cells were seeded on Costar 12 mm Snapwell inserts with a 0.40 µm polycarbonate filter and a seeding density of 0.25 × 106 and studied at 15 d postconfluence. Cells were treated with 10 nM of either 1,25(OH)2D3 or vehicle for 48 h and then mounted in modified Ussing chambers for transepithelial measurements. In Exp. 2, pigs (n = 32) were removed from sows at 3 d of age, placed on a vitamin D-deficient milk replacer diet and housed in a room devoid of sunlight and UV light in the range of 280 to 300 nm. On day 28, serum 25(OH)D3 concentrations were measured to verify low vitamin D status. Pigs (BW 10.10 ± 0.38 kg) were then individually housed day 28 postweaning and allotted to 1 of 2 dietary treatments. Dietary treatments consisted of corn-soybean-based diets with vitamin D supplementations of 0 or 1,500 IU/kg diet for 12 d. Blood samples were taken from the brachiocephalic vein on the initial (day 0) and final day (day 10, 11, or 12) of the study for analysis of serum 25(OH)D3, P, and Ca. Pigs were euthanized and jejunal segments were harvested and used in modified Ussing chambers and for RNA isolation and subsequent quantitative RT-PCR analysis. In Exp. 1, treating Caco-2 cells with 10 nM 1,25(OH)2D3 resulted in a 52% increase (P < 0.005) in Na+-dependent phosphate uptake compared with cells treated with a vehicle. In Exp. 2, Na+-dependent phosphate and glucose transport did not differ (P > 0.10) among treatment groups. Additionally, NaPi-IIb and calbindin D9k mRNA expression were not different (P > 0.10) between treatment groups. No differences (P > 0.10) were detected in final serum P or 25(OH)D3 concentrations between treatments. However, serum Ca linearly increased (P < 0.05) as the concentration of supplemental vitamin D increased in the diet. Overall, while 1,25(OH)2D3 stimulated Na+-dependent phosphate uptake in Caco-2 cells, supplementing diets with 1,500 IU/kg vitamin D3 from cholecalciferol did not increase jejunal Na+-dependent phosphate uptake or NaPi-IIb mRNA expression over that of pigs fed diets with no supplemental cholecalciferol. 相似文献
48.
不同药剂处理对库尔勒香梨枝条抗冻性的影响 总被引:1,自引:0,他引:1
以库尔勒香梨为试验材料,秋季落叶前2周进行水杨酸(SA)0.5,1.0,2.0 mmol/L,腐胺(Put)1.0,5.0,10.0 mmol/L,亚精胺(Spd)0.5,1.0,2.0 mmol/L等3个药剂、9个不同处理,取样后在人工低温处理条件下分析库尔勒香梨的抗冻性。试验结果表明,相对电导率、脯氨酸、MDA、SOD的累积贡献率达到94.1%,可作为库尔勒香梨主要的抗寒性鉴定指标,其中,相对电导率贡献率为71.6%,可单独作为库尔勒香梨抗寒性的鉴定指标。3种药剂处理后枝条的抗冻强弱顺序为1.0 mmol/L SA〉2.0 mmol/L SA〉5.0 mmol/L Put〉1.0 mmol/L Spd〉0.5 mmol/L Spd〉对照。在生产实践中,可根据实际情况于果实采收后喷施浓度1.0-2.0 mmol/L的水杨酸,以提高库尔勒香梨在越冬期的抗冻性。 相似文献
49.
Compliance with a 10-day course of oral antibacterial drugs in dogs being treated as outpatients at a veterinary clinic was assessed by use of pill count data obtained by telephone interview. The association between compliance and several possible determinants of compliance was investigated. Ninety-five animal owners were included in the study, with 44 per cent reporting 100 per cent compliance with the treatment regimen and as many as 88 per cent reporting a compliance level of 80 per cent or more. The compliance level was significantly higher (P < 0.002) when the animal owners felt that the veterinarians spent enough time on the consultation. Moreover, compliance was significantly higher (P < 0.05) for dogs being treated for gastrointestinal infections compared with those being treated for other diseases. 相似文献
50.
Eddy de Grave Paul M. A. de Bakker Lawrence H. Bowen Robert E. Vandenberghe 《植物养料与土壤学杂志》1992,155(5):467-472
Applied-field Mössbauer spectra are reported for selected synthetic samples of α-Fe1-xAlxOOH, γ-Fe1-xAlxOOH, δ-FeOOH, α-(Fe1-xAlx)2O3 and γ-Fe2O3. Field strengths of up to 90 kOe were used at temperatures of mostly 4.2 K. The effects of the Al substitution and/or the crystallinity are discussed. Specific characteristics of the spectra are enlightened which might serve as complimentary sources of information for the characterization of soil oxides and oxyhydroxides. It is pointed out that several questions remain unanswered to date and that further systematic research is justified. 相似文献