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21.
22.
湟源山坡地梯田退耕还林还草效果研究初报   总被引:1,自引:0,他引:1  
通过对湟源山坡地梯田退耕还林工程连续9年的定点观测调查,结果表明:在顶坡梯田,所栽植的榆树Ulmus pumila有94%死亡,沙棘Hippophae rhamnoides有19.4%死亡;在中坡梯田,榆树、沙棘的死亡率分别为93%、18.2%;在底坡梯田,榆树、沙棘的死亡率分别为92.7%、18.6%;而柠条Caragana korshinskii在3个坡位梯田中都100%的成活,但长势不旺,而以赖草Leymus secalinus为主的草本植物,通过9年的自然侵入生长,其生物量(干物质)达到850 g/m2以上。同时,对各坡位草本产量增长规律进行了分析论述,建立了3个坡位草本产量与生长年限回归方程,中坡:y=78.033+102.473 3x;底坡:y=67.333+102.253 3x;顶坡:y=54.244 4+101.92x;如实评估了坡地梯田退耕还草后的经济效益。  相似文献   
23.
The aim of this study was to evaluate the use of Doppler ultrasonography to monitor vascular blood flow dynamics in defined diseases of the equine digit in a noninvasive way. Doppler sonography was used to evaluate medial digital artery blood flow in eight horses with septic pododermatitis and four horses with laminitis in comparison with 10 horses of a control group. Doppler sonographic measurement and lameness examinations were performed in lame horses before treatment (day 0) and at 3, 6, and 9 days following treatment. Before treatment, blood flow velocities, arterial diameter, and flow volume were significantly higher in the lame horses, while pulsatility indices (PIs) were significantly lower (P < 0.05). Compared with the control group, there was no significant difference of resistive indices (RI) in the septic pododermatitis group, but these indices were significantly lower in the laminitis group. No significant difference between the two lame groups was recorded. After treatment, blood flow velocities and flow volume decreased significantly and PIs increased significantly in both lame groups, while RI and arterial diameter did not change. No correlation between Doppler parameters and the degree of lameness was found. Doppler sonography can be used to monitor vascular blood flow dynamics in horses suffering from septic pododermatitis and laminitis, while blood flow velocities and PI can serve as parameters for monitoring the course of the disease.  相似文献   
24.
郑淑惠 《青海草业》2010,19(3):40-42,51
分析了退耕还林(草)现状,结果表明,退耕还林草的后续产业发展不足,提出发展退耕还林草的后续产业对策。  相似文献   
25.
DIAGNOSTIC ULTRASOUND IMAGING OF SOFT TISSUES IN THE BOVINE DISTAL LIMB   总被引:4,自引:0,他引:4  
In this study sonographic images of healthy flexor tendons, digital flexor tendon sheaths, metacarpophalangeal and metatarsophalangeal joints, and proximal and distal interphalangeal joints of the bovine limb were made. Then, synovial cavities in cadavers were filled with the necessary amount of fluid to make the lumina visible sonographically. After injecting 30–40 ml of saline solution into the digital flexor tendon sheath and into the metacarpophalangeal and metatarsophalangeal joints, or 8 ml in the proximal interphalangeal joint and 10 ml in the distal interphalangeal joint, the pouches of these synovial cavities were clearly demarcated. Afterwards, the sonographic image of synovial cavities distended by various inflammatory content were described. When the sonographic findings were compared to the findings in clinical patients, centesis and intraoperative procedures, there appeared to be a relationship as to the extent and location of the disorders as well as to the nature of the synovial effusion. Finally, we identified which planes on diseased bovine distal limbs were appropriate for obtaining optimal sonographic images.  相似文献   
26.
The onset of severe injury to the superficial digital flexor tendon (SDFT) is extremely difficult to predict from slight changes in ultrasonographic findings in cases with no apparent clinical signs. This study investigated the relationship between an increased cross-sectional area (CSA) or edema in the subcutaneous tissue around the tendon and the subsequent onset of severe SDFT injury in Thoroughbred racehorses. Horses were classified into three groups based on ultrasound diagnosis (USD) findings: Group A included cases with enlarged tendons; Group B included cases with tendons of normal size but with prominent edema in the peritendinous tissue; and Group C (control group) included cases with no abnormal USD findings. The incidence of subsequent severe tendon injury was significantly higher in the horses in Groups A (25.7%, 28/101) and B (28.3%, 65/212) than in those in Group C (4.9%, 2/41). There were no significant differences in the median period and the median number of races from the first examination to the subsequent tendon injury between Groups A (140 days, 1 race) and B (120 days, 1 race). The results of this study revealed that horses with increased CSA and peritendinous edema are likely to suffer a subsequent severe tendon injury. Also, these two USD findings, i.e., increased CSA and peritendinous edema, indicate the risk of onset of severe SDFT injury.  相似文献   
27.
Abstract

We review and discuss the applicability of mixed stands in the context of sustainable forestry in southern Sweden. This is done from a silvicultural perspective regarding aspects such as regeneration, pre-commer-cial thinnings, production, economy, damage and policy implications. The paper is based on literature reviews and on studies performed in southern Sweden or under comparable conditions. After considering the underlying mechanisms, we find that it is possible to establish a mixed stand in the regeneration phase and sometimes even to a lower cost compared to monocultures. To keep the mixture, or to create it, with pre-commercial thinnings is, however, often more expensive. The reviewed studies, together with a new simulation, show that the effect on productivity of mixed stands compared to monocultures is minor. Some positive effects on damage (i.e., decreased levels) in mixed stands have been found. The economy and the policy implications of mixed stand management were found to be dependent on the specific stand and situations. A general finding was that research and knowledge of managing mixed stands, as compared to monocultures, are limited, which in turn could limit the applicability of mixed stand management.  相似文献   
28.
数码照相技术用于评价草坪颜色的参数研究   总被引:7,自引:0,他引:7  
田间条件下,比较了拍摄高度、角度、光强和分辨率对所获得的图像颜色参数的影响,分析了图像颜色参数与草坪草地上部全氮含量的相关性,结果表明:数字图像颜色参数中灰度(H)和绿红光比值(G/R)与草坪地上部植株全氮含量相关性最好,达极显著水平;自然光照条件下,拍摄高度、角度、光强和分辨率对所获得的图像颜色参数H和G/R均没有影响.  相似文献   
29.
九江市林业产权制度改革现状分析与建议   总被引:1,自引:0,他引:1  
江西省是我国南方重要的集体林区之一,九江市作为江西省的林业大市,其林业在九江社会经济发展中占有重要地位。九江市林权制度改革时间较早,2004年在武宁县开始试点后推开,2007年主体改革结束,并通过江西省林权制度改革领导小组的全面检查验收。笔者通过对九江市林权制度改革现状进行分析,指出林权制度改革中出现的问题,从龙头企业...  相似文献   
30.
关于黑龙江省森林食品资源开发利用的思考   总被引:1,自引:0,他引:1  
通过对黑龙江省森林食品资源及产业现状的优势分析,提出了森林食品产业发展的措施及建议,以期为促进森林食品资源的合理开发利用,调整森林食品产业结构,增加林区经济收入提供参考。  相似文献   
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