丹麦的森林可持续经营策略

丹麦的森林可持续经营策略王琦，徐斌森林可持续经营是指以一定的方式管理森林和林地，并以一定速率利用森林和林地。一方面，维持森林现有的和未来的生物多样性、生产力、更新能力、生命力和它们所拥有的一切潜力，并在地区、国家和全球水平上维持与其相关的生态、经济和...     

莳养盆栽桂花的四点经验

一、抽土换土,提高肥力。盆栽桂花土量有限,易板结,难保肥。应于每年清明节前后整一次树盘,将1/3的盆土从上至下挖出,换上培养土,并分层埋入适量的驴蹄、马掌。3年一轮,循环不断。在换土过程中,难免损伤一部分侧根、须根,无关紧要,不必担心。因为这样处理后,会诱发更多的新根,长势更旺。此法更适用于大盆老桩,可免翻盆之苦。二、经霜冻,晚入室。北方冬天寒冷,盆栽桂花不能露天存放。可于初冬经2—3次轻霜冻(不要低于     

对养猪生产造成巨大损失的猪疥癣

北卡罗来纳州立大学的研究人员 J.J.Arends,C.M.Stanislaw 和 D.Gerdon 为了解疥癣对母猪及其仔猪从出生到屠宰的生产力的影响情况,进行了一次试验。该试验共分6组,每组16～20头妊娠母猪。妊娠期母猪饲养在帘子相隔、明沟冲洗的待产舍里,每圈5～6头。种公猪则饲养在用帘于相隔的种猪棚内,每厩1头。母猪临产前转入可控制环境的产仔舍里,舍内为全漏缝地板,每厩饲养1头。在试验的后期,生长猪转入肥育舍内,舍也是全漏缝地板,厩与厩之间也用帘子相隔开。     

子夜奇观

该石为黄河石。仰而望之,云淡星稀,银汉无声,轮月朦胧而偏西;俯而察之,茫茫九派流大海,波浪翻滚不停息。天地交融,动静相济,浑然一本,是一幅多么美妙、神奇的子夜堪图啊!大矣哉!(2002年获中国泰山国际奇石博     

A review of the experimental use of antimicrobial agents in the treatment of periodontitis and gingivitis in the dog

Tetracycline, metronidazole, and chlorhexidine have been tested for their effectiveness in the treatment of periodontitis in dogs under experimental conditions. Tetracycline has been effective in reducing bone resorption in dogs with periodontitis when used in the long-term. When used for short times, it can result in reduction of the numbers of microorganisms that are associated with disease. Tetracycline can inhibit the activity of mammalian collagenase thought responsible for the destruction of alveolar bone and it may be capable of inhibiting the adherence of microorganisms and thus preventing infection. In some experiments, metronidazole was more effective than tetracycline in eliminating spirochetes from the periodontal flora, and it has been found effective in preventing the inflammation and the development of the bacterial flora usually associated with the natural accumulation of plaque. Chlorhexidine (0.2% aqueous solution) has been found effective in preventing the normal progression of periodontal disease when used as a spray for the long-term treatment of dogs. It could prove to be as effective as brushing for the long-term control of periodontitis in the dog. Limited information is available on the use of clindamycin, spiramycin, and vancomycin.     

Blood thiamine levels in normal cattle and sheep at pasture

Analysis of whole blood samples from 174 cattle and, 174 sheep from 3 geographical regions of New Zealand over a 10 month period showed a mean (range) thiamine level of 122 nmol/l (71-237 nmol/l) for cattle and 118 nmol/l (67-227 nmol/l) for sheep. Regional and seasonal differences were noted with levels tending to rise over the summer period. A reference range of 75-185 nmol/l is proposed for both cattle and sheep to cover these variations. Levels below 50 nmol/l are considered indicative of deficiency.     

Serum bile acids: reference values in healthy dogs and comparison of two kit methods

Serum bile acid (SBA) reference intervals were established by use of a radioimmunoassay method for fasting dogs to be 0.2 to 4.3 micro mol/L (n = 60) and for 2 hour postprandial samples to be 0.6 to 24.2 micro mol/L (n = 37). The SBA reference intervals estimated using an enzymatic method were 0 to 8.6 micro mol/L for fasting (n = 26) and 0 to 29.8 micro mol/L for 2 hour postprandial samples (n = 36). The correlation between the two methods including samples from healthy dogs and clinical cases is good (n = 128, r = 0.82, p < 0.0001). The radioimmunoassay method is linear to 50 micro mol/L and the enzymatic method is linear to 100 micro mol/L, thus both methods require serum dilutions to be made in many cases of primary liver disease. The enzymatic method is less expensive and more convenient for use in a clinical laboratory but requires a greater sample volume (400 micro I) than the RIA method (50 micro I). Both methods have adequate precision and accuracy to be useful as diagnostic tests of liver function in dogs.     

Geologic youth of galapagos islands confirmed by marine stratigraphy and paleontology

Six distinctive types of fossiliferous marine deposits occur on the Galádpagos Islands that provide evidence for the age of emergence of the islands above sea level and hence a maximum age for the islands' terrestrial biota. These subtidal to supratidal deposits include (i) volcanic tuffs with fossils, (ii) limestones and sandstones interbedded with basalt, (iii) terrace deposits, (iv) beach rock, (v) supratidal talus deposits, and (vi) recently uplifted tidal and subtidal rocks and sand. With the exception of (vi), the deposits were previously assigned ages varying from Miocene to Pleistocene, but all are less than about 2 million years old. This age, together with independently determined geologic ages, indicate that the islands emerged from the sea relatively recently and that all evolution of the islands' unique terrestrial biota occurred within the past 3 to 4 million years.