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971.
利用常规资料,从环流背景场、不稳定能量、物理量场、卫星云图等方面,对2016年6月15-16日西藏雅鲁藏布江一线出现的一次强降水天气过程进行诊断分析.结果表明,欧亚中高纬经向环流强,中高层雅鲁藏布江一线深厚的切变线是此次降水的重要系统;中低空气旋的发展、冷平流的入侵及湿舌的西北方向伸展到雅鲁藏布江一线为此次降水提供动力条件和水汽条件;湿度层厚、对流有效位能大,且处在上干冷、下暖湿的大气环境下,为拉萨的强降水提供了有利条件.  相似文献   
972.
A perioperative antibiotic for equine castration with second intention healing is controversial because the necessity is unclear and antimicrobial use promotes the selection of resistant bacteria. Information about different regimes for perioperative antimicrobial prophylaxis in equine castration is sparse. Goal of this study was to compare clinical findings, acute-phase proteins, and bacterial cultures in horses undergoing castration, treated with an intravenous single administration of penicillin G sodium (1× Pen group) or a 3-day course of daily intramuscular procaine penicillin (3× Pen group). Forty-eight stallions were castrated under general anesthesia using a closed technique, with second intention healing. Serum amyloid A (SAA) and fibrinogen were measured on days 0, 3, and 8. Body temperature, wound swelling, and drainage were recorded daily over 10 days. Bacterial swabs of the wound were taken on days 0 and 3. Scrotal swelling (P = .032), amount of drainage from the wound (P = .039), and body temperature (P = .013) on day 8 after castration were significantly higher in the 1× Pen group. The concentration of SAA and fibrinogen on day 8 was significantly higher in the 1× Pen group compared with the 3× Pen group (SAA: P = .049; fibrinogen: P = .035). β-Hemolytic Streptococcus spp. were found more frequently cultured in the 1× Pen group than in the 3× Pen group. Clinical and laboratory data indicate lower inflammatory reaction in the early postoperative period after three applications of penicillin compared with a single-administration. Further investigations evaluating the long-term outcome and potential development of antimicrobial resistant bacteria are needed.  相似文献   
973.
于泰格林纸集团公司在岳阳地区营造的不同立地指数的湿地松纸浆林设置样地,对不同立地指数林分的生长进行调查研究。结果表明:立地指数为15、13、11的14年生湿地松纸浆林平均树高分别为10.0、7.9、6.0 m,平均胸径分别为14.5、12.6、10.9 cm,林分单位面积蓄积量分别为145.4、92.0、55.7 m~3/hm~2。不同立地指数湿地松林单位面积蓄积量差别极大,立地指数为11的林分蓄积量仅为立地指数为15林分的38.3%,立地指数为13的林分单位面积蓄积量也仅为立地指数为15林分的63.3%。因此,在岳阳地区营造湿地松速生丰产纸浆林,应尽可能选择立地指数为15的林地。  相似文献   
974.
为阐明睾酮在鹿角柄发生过程中的作用机理,本文对6头梅花鹿的生茸区骨膜和头部的非生茸区骨膜的睾酮特异结合进行了测定。所得结果为,正常、去势雄仔鹿的生茸区骨膜中都存在一定量的睾酮特异结合(分别为:正常,细胞质为29.32,细胞核为169.63;去势,细胞核为595.84。单位:fmol/mg蛋白),而非生茸区骨膜却未测到这种特异结合;雌鹿的测定结果为,除去势雌仔鹿生茸区骨膜具有一定量的睾酮特异结合(细胞核为223.21fmol/mg蛋白)外,其余生茸区和非生茸区均不存在睾酮特异结合。这些结果表明,雄仔鹿和去势雌仔鹿生茸区骨膜中可能存在着一定量的雄激素受体,这种骨膜在特定的生理条件下受睾酮的直接作用,是睾酮的靶组织。  相似文献   
975.
A. Elgersma  R. ?nie?ko 《Euphytica》1988,39(Z3):59-68
In seed crops of perennial ryegrass, Lolium perenne L., yields are low and only 15 to 20% of the florets produce a harvestable seed. This study was conducted to determine if seed abortion was a major cause of low floret site utilization (FSU) and therefore of low seed yield in spaced plants. Spikes of four spaced-planted genotypes of perennial ryegrass were harvested and fixed at one-week intervals one to five weeks after the beginning of anthesis. Of a total of 74 spikes, over 13,000 florets were examined with a binocular microscope and 66 whole spikelets were microtome sectioned. The histology of the pro-embryo is presented in relation to the development of the endosperm. In one low yielding, two intermediate and one high yielding genotype, biological FSU was 8, 72, 73 and 63%, respectively. In all genotypes, 90% of the unproductive florets showed ovule degeneration within a few days after flowering. A few florets were sterile or contained a degenerated embryo sac already before flowering and about 5% of the unproductive florets showed seed abortion later than one week after flowering. Within a spikelet, successful fertilization did not decline from the basal to the distal floret. Although in later stages distal florets had slightly less seeds, unproductive florets were found at all floret positions. Biological FSU decreased mainly by ovule degeneration shortly after flowering. In spaced plants, seed abortion was not important to low seed yield.  相似文献   
976.
977.
辽西河滩地杨树立地分类的研究   总被引:1,自引:0,他引:1  
  相似文献   
978.
根据优势木高度与立地质量的关系及优势木高分面扇形法则等基本原理,采用一元非线性回归,多元数量化回归模型I等基本方法,编绘了豫西日本落叶松人工林地位指数级表和地位指数级曲线图,拟定了优势木高对立地因子的多元线性回归方程。在研究方法上综合地位级法及立地指数法的优缺点,将其改为地位指数法是本研究的一个特色。  相似文献   
979.
Objective To investigate tissue residues of two longacting oxytetracycline (OTC) preparations in cattle.
Design A randomised drug residue trial.  

Animals


Two hundred and forty beef cattle in 24 groups of ten.
Procedure Two blind-coded 200 mg/mL OTC preparations were used in five treatment regimens of various combinations of injection sites (from one to five) and administrations (one or two). Five cattle from each group were slaughtered at 21, 30 and 60 days after injection and the injection site, urine, kidney and diaphragm muscle analysed for residues.
Results The OTC concentration exceeded the maximum residue limit in kidney in animals slaughtered 21 days after treatment, which is the prescribed withholding period. Concentration at the injection site was much greater than the maximum residue limit 30 days post-treatment, but not 45 days post-treatment. The residue was smaller when OTC had been injected in multiple sites. There was no difference between the two OTC preparations.
Conclusion A review of the maximum injection volume, site of injection and the withholding period is needed for long-acting OTC formulations.  相似文献   
980.
根据林木施肥模型,在南岭南坡山地对杉木幼林和中龄林进行了大面积的施肥试验与推广,结果表明,按照该模型的基本步骤进行实施,杉木中龄林可实现增产木材45m3/hm2,平均投入产出比接近达到1:8;杉木幼林施肥,可使林分提前1~3年郁闭,缩短了林木的生长周期,实践证明,本技术可操作性强,理论值与实际值差距小,经济、生态效益显著,可以在条件类似的杉木产区推广应用.  相似文献   
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