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   90篇
  免费   7篇
林业   2篇
  3篇
综合类   18篇
水产渔业   1篇
畜牧兽医   73篇
  2023年   1篇
  2020年   3篇
  2019年   1篇
  2018年   1篇
  2017年   2篇
  2016年   1篇
  2015年   3篇
  2014年   2篇
  2013年   3篇
  2012年   1篇
  2011年   3篇
  2010年   3篇
  2009年   1篇
  2008年   1篇
  2007年   3篇
  2006年   2篇
  2005年   3篇
  2003年   4篇
  2002年   2篇
  2001年   3篇
  2000年   1篇
  1999年   4篇
  1998年   7篇
  1997年   4篇
  1996年   11篇
  1995年   2篇
  1994年   3篇
  1993年   4篇
  1992年   4篇
  1991年   5篇
  1990年   8篇
  1988年   1篇
排序方式: 共有97条查询结果,搜索用时 15 毫秒
11.
12.
Reason for performing study: Studies are required to define more accurately and completely the neuroanatomy of the equine dorsal cricoarytenoid muscle as a prerequisite for developing a neuroprosthesis for recurrent laryngeal neuropathy. Objective: To describe the anatomy, innervation, fibre types and function of the equine dorsal cricoarytenoid muscle. Methods: Thirty‐one larynges were collected at necropsy from horses with no history of upper airway disease and 25 subjected to gross dissection. Thereafter, the following preparations were made on a subset of larynges: histochemical staining (n = 5), Sihler's and acetylcholinesterase staining for motor endplates (n = 2). An additional 6 larynges were collected and used for a muscle stimulation study. Results: Two neuromuscular compartments (NMC), each innervated by a primary nerve branch of the recurrent laryngeal nerve, were identified in all larynges. Stimulation of the lateral NMC produced more lateral displacement of the arytenoid cartilage than the medial NMC (P<0.05). The medial NMC tended to rotate the arytenoid cartilage dorsally. Motor endplates were identified at the junction of the middle and caudal thirds of each NMC. If fibre type grouping was present it was always present in both NMCs. Conclusions: The equine dorsal cricoarytenoid muscle has 2 distinct muscle NMCs with discrete innervation and lines of action. The lateral NMC appears to have a larger role in increasing cross‐sectional area of the rima glottidis. Potential relevance: This information should assist in planning surgical reinnervation procedures and development of a neuroprosthesis for recurrent laryngeal neuropathy.  相似文献   
13.
Effects of small population size and reduced genetic variation on the viability of wild animal populations remain controversial. During a 35-year study of a remnant population of greater prairie chickens, population size decreased from 2000 individuals in 1962 to fewer than 50 by 1994. Concurrently, both fitness, as measured by fertility and hatching rates of eggs, and genetic diversity declined significantly. Conservation measures initiated in 1992 with translocations of birds from large, genetically diverse populations restored egg viability. Thus, sufficient genetic resources appear to be critical for maintaining populations of greater prairie chickens.  相似文献   
14.
Free-standing aligned carbon nanotubes have previously been grown above 700 degreesC on mesoporous silica embedded with iron nanoparticles. Here, carbon nanotubes aligned over areas up to several square centimeters were grown on nickel-coated glass below 666 degreesC by plasma-enhanced hot filament chemical vapor deposition. Acetylene gas was used as the carbon source and ammonia gas was used as a catalyst and dilution gas. Nanotubes with controllable diameters from 20 to 400 nanometers and lengths from 0. 1 to 50 micrometers were obtained. Using this method, large panels of aligned carbon nanotubes can be made under conditions that are suitable for device fabrication.  相似文献   
15.
Ferris  R; Humphrey  JW 《Forestry》1999,72(4):313-328
  相似文献   
16.

Background

The aim of this study was to provide a systematic pathological and parasitological overview of the gastrointestinal tract (GIT), including the stomach, duodenum, jejunum, ileum, caecum and colon, of dogs naturally infected with Leishmania.

Methods

Twenty mongrel dogs naturally infected with Leishmania (Leishmania) infantum and obtained from the Control Zoonosis Center of the Municipality of Ribeirão das Neves, Belo Horizonte Metropolitan area, Minas Gerais (MG) state, Brazil, were analyzed. The dogs were divided into two groups: Group 1 comprised nine clinically normal dogs and group 2 comprised 11 clinically affected dogs. After necropsy, one sample was collected from each GIT segment, namely the stomach, duodenum, jejunum, ileum, caecum and colon. Furthermore, paraffin-embedded samples were used for histological and parasitological (immunohistochemistry) evaluation and a morphometrical study were carried out to determine the parasite load (immunolabeled amastigote forms of Leishmania). The Friedman and the Mann Whitney tests were used for statistical analysis. The Friedman test was used to analyze each segment of the GIT within each group of dogs and the Mann Whitney test was used to compare the GIT segments between clinically unaffected and affected dogs.

Results

The infected dogs had an increased number of macrophages, plasma cells and lymphocytes, but lesions were generally mild. Parasite distribution in the GIT was evident in all intestinal segments and layers of the intestinal wall (mucosal, muscular and submucosal) irrespective of the clinical status of the dogs. However, the parasite load was statistically higher in the caecum and colon than in other segments of the GIT.

Conclusion

The high parasite burden evident throughout the GIT mucosa with only mild pathological alterations led us to consider whether Leishmania gains an advantage from the intestinal immunoregulatory response (immunological tolerance).  相似文献   
17.
18.
Investigations were conducted on several small neighbouring beef cattle and sheep farms that were found to be contaminated with polychlorinated biphenyls (PCBs). The residues detected contained about 62% w/w chlorine and soil concentrations ranged from 0.35 to 1.9 mg/kg. Beef cattle and sheep grazing the contaminated land had PCB concentrations in their fat of 0.3 to 1.7 mg/kg and 0.19 to 0.45 mg/kg, respectively. The concentration of PCBs in the caudal fat of cattle was 0.3 to 2 times the concentration of PCBs in the land they were grazing and was positively related to stocking rates. PCBs were present in milk fat from cattle at about the same concentration as in caudal fat, and lactation appeared to contribute to decontamination. Wool grease from sheep contained about 1 to 2 times the concentration of PCBs in subcutaneous fat. Calves of contaminated cows also became contaminated. The half-life for decontamination of PCBs in a group of 8 young female beef cattle was calculated at 13 months. PCBs were detected in pasture samples at concentrations ranging from less than 0.01 mg/kg to 0.12 mg/kg. However, PCBs were not detected in any sample of hay cut from these paddocks. In 4 sheep fed a sole ration of this hay, traces of PCBs were detected in their fat following 89 days of feeding. Grazing livestock for meat production on land contaminated with PCBs is not recommended because livestock readily acquire residues, and PCBs persist in soil and livestock for long periods. Grazing sheep for wool production on land contaminated with PCBs may be an option.  相似文献   
19.
Congenital dyserythropoietic anaemia (CDA) is a heterogeneous group of rare genetic disorders that in humans is characterised by ineffective haematopoiesis with morphological abnormalities in erythroid precursor cells and secondary iron overload. In the 1990s, a syndrome of CDA with dyskeratosis and progressive alopecia was reported in Poll Hereford calves in Canada and the USA. We report the clinical and pathological findings in two Poll Hereford calves with this syndrome from separate properties in South Australia. The animals had a variably severe anaemia, associated with abnormal nucleated red blood cells in peripheral blood, and large numbers of rubricytes and metarubricytes with a characteristic nuclear ultrastructure in the bone marrow. Both calves were born with a wiry hair coat and a progressively ‘dirty‐faced’ appearance associated with hyperkeratosis and dyskeratosis (apoptosis).  相似文献   
20.
Adenosine is a potent analgesic in people and reduces the MAC of halothane in dogs. The purpose of this study was to determine whether adenosine reduces the MAC of isoflurane in dogs. Seven beagles (four males and three females) were anesthetized and randomly assigned to receive adenosine (0.3 mg kg–1 minute–1; 6 mL kg–1 hour–1, IV) or saline (0.9%, 6 mL kg–1 hour–1IV). After an interval of ≥7 days, each dog was reanesthetized and treated with the alternate infusion. Anesthesia was induced and maintained with isoflurane in oxygen. Dogs were intubated and instrumented for measurement of mean systemic arterial blood pressure and airway concentration of isoflurane and end‐tidal partial pressure of carbon dioxide. The MAC for isoflurane was determined using the tail‐clamp technique. Baseline MAC values were 1.25 (1.15, 1.35)% [median (minimum, maximum)] and 1.25 (1.05, 1.45)% before the saline and adenosine treatments, respectively. After 2 hours of infusion with saline or adenosine, MAC values were not different (p = 0.156) and were 1.25 (0.95, 1.35)% and 1.05 (1.00, 1.25)%, respectively. Two hours following the end of each infusion, the MAC values for saline and adenosine treatment groups differed significantly (p = 0.015), but by no more than the normal variation inherent in this study, and were 1.15 (1.15, 1.35)% and 1.05 (1.05, 1.25)%, respectively. Mean arterial blood pressure was 93 (74, 123) mm Hg for saline treated dogs and 67 (52, 72) mm Hg (p = 0.008) during adenosine infusion. End‐tidal carbon dioxide was not different between the two treatment groups. We conclude that adenosine administered at 0.3 mg kg–1 minute–1had no effect on isoflurane MAC in dogs, but decreased mean arterial blood pressure.  相似文献   
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