Fire cycle of the Canada's boreal region and its potential response to global change     

ZHANG Quan-fa  CHEN Wen-jun .Wuhan Botanical Garden  Chinese Academy of Sciences  Wuhan  P. R. China .Applications Division  Canada Centre for Remote Sensing  Booth Street  Ottawa  Ontario KA Y  Canada 《林业研究》2007,(1)

Interactions of fire cycle and plant species' reproductive characteristics could determine vegetation distribution pattern of a landscape. In Canada's boreal region, fire cycles before the Little Ice Age (c. 1850s) ranged from 30-130 years and 25-234 years afterwards until the settlement period (c. 1930s) when longer fire cycles occurred in response to climatic change and human interference. Analysis indi-cated that fire cycles were correlated with growing season (April-October) temperature and precipitation departure from the 1961-1990 nor-mal, varying by regions. Assuming that wildfires will respond to future warming similar to the manner during the past century, an assess-ment using climatic change scenarios CGCM1, CGCM2 and HadCM2 indicates fire cycles would divert to a range of 80-140 years in the west taiga shield, more than 700 years for the east boreal shield and east taiga shield, and 300-400 years for the boreal plains in 2050.  相似文献   

Adverse reaction to procaine penicillin G in horses     

IL NIELSEN  KA JACOBS  PJ HUNTINGTON†  CB CHAPMAN‡  KC LLOYD§ 《Australian veterinary journal》1988,65(6):181-185

Adverse reactions to intramuscular injections of procaine penicillin G are reported in 11 horses, five of which died. The clinical findings are presented and suggest central nervous involvement in most cases. Post mortem findings in one horse were consistent with anaphylaxis whereas in other cases the clinical findings, duration of treatment, speed of onset and subsequent completion of treatment supports diagnosis of an acute procaine toxicity syndrome.  相似文献   

Ecology of verotoxigenic Escherichia coli     

KA BETTELHEIM 《Australian veterinary journal》1997,75(12):912-912

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A pulmonary adenoma in an Australian sheep     

PT HOOPER  KA ELLARD 《Australian veterinary journal》1995,72(12):477-477

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Sarcoptic mange in wombats   总被引：1，自引：0，他引：1  

LF SKERRATT  RW MARTIN  KA HANDASYDE 《Australian veterinary journal》1998,76(6):408-410

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Tumour angiogenesis,anti‐angiogenic therapy and chemotherapeutic resistance          下载免费PDF全文

KA Mander  JW Finnie 《Australian veterinary journal》2018,96(10):371-378

In order for a tumour to continue to grow and disseminate, it must acquire a new blood supply. Neovascularisation can be enacted by a number of different mechanisms. This dependence of tumour progression on an augmented vascular supply has been exploited by the development of anti‐angiogenic drugs, which are designed to inhibit new blood vessel formation or disrupt existing tumour‐associated vasculature, both leading to ischaemic–hypoxic tumour cell death. However, the clinical benefits of these therapeutic approaches are frequently variable and often transient, the neoplasm sometimes being able to use other neovascularisation mechanisms to maintain its blood supply and thus evade the current anti‐angiogenic therapy. Tumours may also develop a more malignant phenotype following this treatment. Clinical outcomes may be improved by simultaneously inhibiting different angiogenic pathways, abetted by more effective drug delivery regimens such as metronomic chemotherapy and the concurrent use of other antitumour modalities.  相似文献   

The impact of bisphenol S on bovine granulosa and theca cells          下载免费PDF全文

KA Campen  M Lavallee  CMH Combelles 《Reproduction in domestic animals》2018,53(2):450-457

Bisphenol S (BPS) is an endocrine‐disrupting chemical with multiple potential mechanisms of action, including as an oestrogen receptor agonist. BPS is increasingly used in plastics and thermal receipts as a substitute for bisphenol A, which has been phased out due to concerns about human health implications. The ability of BPS to alter female reproductive function in mammals has not been widely studied, despite the importance of normal hormone signalling for female reproduction. The aim of this study was to investigate how BPS (in a wide range of doses, including very low doses) affects granulosa cell and theca cell steroid hormone production and cell viability in the bovine. Granulosa cell oestradiol production was stimulated when cells were exposed to 100 μM BPS under basal conditions, but there was no effect of BPS when cells were stimulated with follicle‐stimulating hormone (FSH). Additionally, there was no effect of BPS on granulosa cell progesterone production or cell viability under basal or FSH‐stimulated conditions. BPS did not affect theca cell androstenedione or progesterone production, or theca cell viability under basal or luteinizing hormone‐stimulated conditions. This study suggests for the first time that BPS may alter oestradiol production by bovine granulosa cells, albeit at a concentration that is unlikely to be physiologically relevant. Further studies are needed to determine the effects of BPS on the bovine oocyte and on other functions of follicular cells.  相似文献   

南疆灌区冬小麦/夏玉米改良模式增产潜力与机理分析     

章建新  赵明  图尔贡  卡地尔亚 《干旱地区农业研究》2013,31(6):15-21

田间试验系统地比较了新冬20/沈玉2002不同套种模式（“522模式”与“952模式”）及“521模式”下保麦10号/蠡玉35、保麦10号/登海3672、新冬20/蠡玉35的产量、叶面积指数、光合势及干物质积累等性状的差异。结果表明,“522模式”新冬20/沈玉2002周年产量（17 838.2 kg·hm^-2）较“952模式”(16 550.9 kg·hm^-2)增产7.8%,其中,冬小麦增产18.4%。“521模式”保麦10号/蠡玉35、保麦10号/登海3672、新冬20/蠡玉35周年产量为19 905.0～20 751.0 kg·hm^-2,其中,冬小麦产量为9 740～10 275 kg·hm^-2、夏玉米产量为9 630～10 211.0 kg·hm^-2;冬小麦孕穗期和开花期叶面积指数分别为6.0、5.0左右,返青至成熟的总光合势290.2～324.3×10⁴·m²·d·hm^-2;夏玉米生育期111 d,大喇叭口期至吐丝后20 d的叶面积指数均保持在4左右,生育期间总光合势233.1～257.5×10⁴·m²·d·hm^-2,冬小麦和玉米总光合势为523.3～581.8×10⁴·m²·d·hm^-2;总干物质量38 569.1～40 487.0 kg·hm^-2;冬小麦产量的边际效应为85.7%～112.9%。“521模式”比“952模式”大幅度增产,是小麦行数和边行数及边际产量增大的结果,并将夏玉米播期提至麦收前15 d左右,延长玉米生育期（达110 d左右）,优化株行配置使玉米增产显著,实现全年超高产。“521模式”同时充分利用了冬小麦边际补偿效应和玉米时间补偿效应,较“952模式”易获得周年超高产。并对超高产栽培技术进行了讨论。  相似文献   

Preliminary Studies on Cryopreservation of Common Tench (Tinca tinca) Embryos (Work in Progress)     

KA El-Battawy  O Linhart 《Reproduction in domestic animals》2009,44(4):718-723

Vitrification could provide a promising tool for the cryopreservation of fish embryos. However, to achieve cryopreservation using vitrification, chilling sensitivity and cryoprotectants toxicity were determined using tench embryos at four developmental stages (11, 17, 23 and 29 h). Embryos treated with alcalase (2 ml/998 ml, 2 min at 22°C) were exposed to chilling with/without warming. Other embryos were exposed to methanol and glycerol at the concentration of 10% and 20% for periods of 20 min. At last, embryos were incubated at special incubator cages where hatching rates were counted. Regarding chilling sensitivity and exposure to chilling followed by warming, the hatching rates of embryos decreased significantly (p < 0.001) after exposure to 0°C at all developmental stages except the 29-h stage compared with the controls. The embryo stage most sensitive to chilling was 11-h stage. The 29-h stage exhibited the least sensitivity to low temperature while 17-h and 23-h stages were intermediate in their sensitivity to chilling. The toxicity of methanol increased significantly (p < 0.001) with developmental stage for 11, 17 and 23-h stages. The highest hatching rates of tench embryos were obtained with 29-h embryos using various concentrations of methanol. The hatching rates of tench embryos exposed to glycerol concentrations were approximately similar to those embryos exposed to methanol concentrations except for 11-h embryos that showed no hatching. Unfortunately, we could not obtain living embryos in any of the conditions examined after vitrification. In conclusion, it was quite difficult to vitrify the tench embryos during this study using various vitrifying solutions and the method reported by Chen & Tian (2005) and further studies are needed to achieve successful cryopreservation.  相似文献   

Trichostrongylus axei infection as a cause of deaths and loss of weight in sheep     

KA ABBOTT  IJ MCFARLAND 《Australian veterinary journal》1991,68(11):368-369

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