首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   96篇
  免费   3篇
林业   1篇
  7篇
综合类   25篇
畜牧兽医   64篇
植物保护   2篇
  2020年   3篇
  2019年   2篇
  2018年   2篇
  2017年   1篇
  2015年   1篇
  2014年   3篇
  2013年   4篇
  2012年   3篇
  2011年   4篇
  2010年   3篇
  2009年   4篇
  2008年   2篇
  2007年   1篇
  2006年   2篇
  2005年   2篇
  2003年   4篇
  2002年   2篇
  2000年   1篇
  1999年   2篇
  1998年   6篇
  1997年   10篇
  1996年   9篇
  1995年   4篇
  1994年   1篇
  1993年   3篇
  1992年   3篇
  1991年   4篇
  1990年   1篇
  1989年   5篇
  1988年   1篇
  1987年   2篇
  1985年   1篇
  1984年   1篇
  1981年   1篇
  1945年   1篇
排序方式: 共有99条查询结果,搜索用时 15 毫秒
71.
Research during the mid 1980s identified acidified, forested catchments in central Scotland whose hydrochemistry was not capable of supporting native fish populations. Calcium concentrations were around 20 μeq l?1, less than the suggested critical value of 50 μeq l?1, with hydrogen concentrations around 70 μeq l?1, greater than the critical value of about 30 μeq l?1. Limestone was applied by aerial application to the source areas of selected streams in 1990 with around 5% (15 ha) of the total catchment area of 270 ha treated at 10 tonnes ha?1. Stream monitoring, carried out over the period 1989–1995, showed an immediate response to liming followed by a progressive decline. Calcium values were elevated to >150 μeq l?1 and hydrogen concentrations reduced to 20 μeq l?1, reverting in time towards pre-liming values. Although salmonid survival was improved during low flow conditions in summer, only a few fry survived to the autumn as acid episodes increased, and these were subsequently lost from the system during the winter period. Budget calculations indicated losses of around 30% of the applied calcium during the first four years. Studies on the vegetation and soils revealed a greater than expected penetration of calcium to depth (10–20 cm) in the soil profile. Results suggest that source area liming at this rate has had minimal effects on the vegetation and by increasing the proportion of the catchment limed to 15% could have a much greater success in reducing the frequency of biologically damaging episodes.  相似文献   
72.
Grodon首先于1980年报道,转移克隆化的外源DNA到小鼠体中,而使小鼠的所有细胞都含有外源基因。随后又有很多类似报道,被整合的外源基因,即转基因被稳定地整合到转基因动物的基因组中,并按孟德尔方式遗传。然而,转基因动物内在的潜力却首先是由Palmiter等(1982)证明的。他们发现,当转移到小鼠体内的生长激素基因表达时,明显增加了生长速度。近十年来,转基因小鼠通常都用做研究工具,很多实验室试图应用这一技术来改变家畜的基因型。到本世纪末或下世纪  相似文献   
73.
74.
SUMMARY Mice trapped on farms in south-eastern Queensland had chronic abscessating osteoarthritides mainly involving the carpi and tarsi. Pleomorphic bacteria were shown by silver staining to be plentiful within lesions. Streptobacillus moniliformis was isolated from the joints, and streptobacillary polyarthritis was diagnosed. Other lesions observed included subcutaneous and hepatic abscesses.  相似文献   
75.
76.
77.
Objective   Describe the use of a phalangeal cast as treatment for wounds in the pastern and foot region of horses. Secondly, to evaluate the healing and soundness of horses treated with phalangeal casts.
Design   Retrospective study of 49 horses.
Procedures   Medical records of 49 horses that were treated with a phalangeal cast for 50 cases of wounds in the pastern and foot region at equine referral hospitals from 1995 to 2006 were reviewed and follow-up information was obtained.
Results   Treatment consisted of wound debridement, lavage, wound closure (28 wounds), cast application and antibiotics (84%). At follow-up, the majority of horses were sound (42 of 47 wounds, 89.4%), three horses were still lame and one horse was euthanased because of persistent lameness. Three horses were lost to follow-up. There was no statistical difference between the outcomes of horses treated acutely (<24 h) or after a 24-h delay. Similarly, the involvement of synovial structures in the wound did not significantly influence outcome.
Conclusions   In this study, wounds involving the pastern and foot that were treated with a phalangeal cast carried a good prognosis for soundness (89.4%) and cosmetic healing (89.5%). The phalangeal casts were well-tolerated and effective.  相似文献   
78.
79.
The aim of this study was to assess the efficacy and safety of deslorelin acetate implants on domestic queen puberty postponement. Thirty, 114.4 ± 12.7 days old, 1.5 ± 0.1 kg prepubertal crossbred female cats were included in this study. The animals were kept under a positive photoperiod and randomly assigned to deslorelin acetate 4.7 mg SC implants (n = 15) or to a non‐treated control group (n = 15). The queens were followed up daily and weighed weekly until puberty. Vaginal cytology was also carried out three times a week. Puberty was diagnosed by the presence of the typical oestrous behaviour and vaginal cytology findings. At puberty, ovariectomy was performed and the gonads grossly described. Age (281.2 ± 21.6 vs 177.8 ± 10.8; p < 0.01) but not weight (2.6 ± 0.1 vs 2.5 ± 0.1; p > 0.1) at puberty differed between the deslorelin and control groups, respectively. One deslorelin‐treated female showed an oestrous response and another showed clinical signs of pyometra after the implants. Deslorelin‐treated ovaries appeared small, while control gonads were normal. It was concluded that long‐term‐release deslorelin, administered at approximately 50% adult body weight, postponed feline puberty without altering growing rate.  相似文献   
80.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号