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   101篇
  免费   5篇
林业   4篇
  17篇
综合类   7篇
农作物   4篇
水产渔业   15篇
畜牧兽医   52篇
园艺   3篇
植物保护   4篇
  2020年   4篇
  2018年   2篇
  2017年   1篇
  2016年   6篇
  2015年   4篇
  2014年   4篇
  2013年   13篇
  2012年   4篇
  2011年   7篇
  2010年   2篇
  2009年   5篇
  2008年   4篇
  2007年   6篇
  2006年   4篇
  2005年   7篇
  2004年   3篇
  2003年   5篇
  2002年   3篇
  2001年   2篇
  2000年   1篇
  1999年   1篇
  1995年   2篇
  1994年   1篇
  1992年   1篇
  1991年   1篇
  1988年   2篇
  1986年   1篇
  1983年   3篇
  1982年   1篇
  1978年   2篇
  1974年   2篇
  1973年   1篇
  1971年   1篇
排序方式: 共有106条查询结果,搜索用时 15 毫秒
91.
In this study the animal welfare legislation and three private standards in Sweden, focusing on dairy cows, were analysed. The aim was to investigate to what extent these regulations consisted of resource-, management- or animal-based requirements, to analyse the content and discuss consequences. The results showed a higher proportion of management- and resource-based requirements than animal-based in all regulations. However, the borders between these categories were not as distinct as expected. The private standards put slightly more emphasis on the animal-based requirements and on animal welfare at herd level. It was primarily the organic standard that included higher animal welfare demands than the legislation. Due to vague wording and guideline statements it was not always clear if the welfare level achieved would be the same in practice although the requirements were similar. It will be necessary to clearly distinguish between requirements and measures to make the policy process more transparent.  相似文献   
92.
93.
A method is presented for preparing samples of freeze-dried mixtures of microorganisms for proficiency tests and collaborative studies. The samples may include most microorganisms that are found in routine analysis in food laboratories. Transport of samples during 48 h did not decrease the number of microorganisms, nor was the variability among samples significantly affected by transport. The standard deviation of counts after 5 weeks of storage varied from 0.04 (Staphylococcus aureus) to 0.17 (Clostridium perfringens) log unit. Storage of samples for 10 weeks decreased the number of viable organisms by 0.02-0.43 log unit. Variability among samples increased for Providencia alcalifaciens and Bacillus cereus after 10 weeks of storage. No significant increase was found for the other organisms.  相似文献   
94.
A method of percutaneous arterial blood sampling in piglets has been developed and determinations of arterial pH, pCO2, pCO2, BE, HGO3 , LA and Hb have been performed in 121 piglets 1–3 days of age. The validity of these measurements has been tested and proved valid for clinical practice with the exception of pO2 and LA values. The correlations with age were statistically significant but poor and therefore the mean values are presented as reference values. These were: pH: 7.423±0.082, PCO2: 4.98±0.74 kPa, BE: 0.4±4.1 mmol/1, HCO3: 23.0+3.2 mmol/1 and Hb: 88±14 g/1.  相似文献   
95.
A survey of 100 cases of oxyquinoline poisoning in dogs is presented. The disease, characterized by hyperexcitability of the CNS with convulsions as well as heart and liver injury, runs an acute course. The mortality (euthanized dogs included) was 30 %. Case-history data showed that the oxyquinoline treatment which preceded the disease was given because the dog had incidental diarrhoea. In most cases the drugs were administered for only 1 day before the dog fell ill. The median time from the last dose to onset of symptoms was 12 hrs. Old dogs were affected more often than expected and also showed higher mortality than did young dogs.  相似文献   
96.
Cucurbit powdery mildew (CPM) is one of the most important plant protection problems in Swedish cucumber production. CPM fungi have developed resistance to the commonly used fungicide (Imazalil) rendering its current use less effective. We therefore screened a selection of alternative products, evaluating their ability to control CPM in seven small-scale, semi-commercial, greenhouse experiments. Products were screened for their ability to suppress CPM on a susceptible cultivar, in 2013. In 2015, the best treatments were tested in different combinations, in different intervals on a susceptible and a partially resistant cultivar. The treatment that gave the best CPM control was Sakalia in combination with wetting agent Yuccah, (based on Reynoutria sachaliensis and Yucca schidigera respectively) applied at 7-day intervals. This treatment was highly efficient on both cucumber cultivars. Sakalia mixed with Yuccah applied at 14-day intervals had an almost equally controlling effect on CPM. The microbial pesticides, Polyversum (Pythium oligandrum) and AQ10 (Ampelomyces quiscalis) and the fungicide Imazalil, provided no to poor control of CPM compared to control treatments. Hortistar (Silicon) partially reduced CPM infections and was more efficient on the partially resistant cultivar. We conclude that Sakalia in combination with wetting agent Yuccah could efficiently control the disease even under the severe conditions caused by artificial inoculation. Further testing of this combination in commercial greenhouses will enable evaluation of the potential effects on yield and beneficial or pest insects. The knowledge gained from this study can be used to develop IPM tools for commercial production systems.  相似文献   
97.
Population structure of Reyna Creole cattle in Nicaragua   总被引:1,自引:1,他引:0  
Reyna Creole cattle originated from Bos taurus cattle brought to Latin America during the Spanish colonization in the fifteenth century and are the only remaining local breed in Nicaragua. However, the current genetic status of this breed is unknown. Therefore, the population structure of three recorded Reyna Creole herds in Nicaragua was studied to estimate their level of inbreeding, effective population size, and generation intervals. Data from 2,609 animals born between 1958 and 2007 were analyzed. A pedigree completeness index higher than 0.8 was required to obtain reliable estimates of the level of inbreeding, and this criterion was met for 367 animals (14%) in two herds. The average level of inbreeding was 13.0%, with values ranging from 0% to 43.8% for individual animals. One of the herds had an average inbreeding level of 21.6%, primarily due to long periods in which the same bulls were used for mating, leading to excessive frequencies of matings between closely related animals. The effective population size differed between years and ranged from 28 to 46 animals, showing that the Reyna Creole cattle breed is endangered, close to critical status. The average generation interval was 6.9 years with values as high as 19.1 years for some sires that were used for artificial insemination over a long period of time. Due to the high level of inbreeding and small population size, urgent actions are required for the development of a breeding program to protect the breed and support its sustainable utilization.  相似文献   
98.
OBJECTIVE: To determine whether disruption of adenine triphosphate (ATP) regeneration and subsequent adenine nucleotide degradation are potential mechanisms for rhabdomyolysis in horses with polysaccharide storage myopathy (PSSM) performing submaximal exercise. ANIMALS: 7 horses with PSSM and 4 control horses. PROCEDURES: Horses with PSSM performed 2-minute intervals of a walk and trot exercise on a treadmill until muscle cramping developed. Control horses exercised similarly for 20 minutes. Serum creatine kinase (CK) activity was measured 4 hours after exercise. Citrate synthase (CS), 3-OH-acylCoA dehydrogenase, and lactate dehydrogenase activities prior to exercise and glucose-6-phosphate (G-6-P) and lactate concentrations before and after exercise were measured in gluteal muscle specimens. Adenine triphosphate, diphosphate (ADP), monophosphate (AMP), and inosine monophosphate (IMP) concentrations were measured before and after exercise in whole muscle, single muscle fibers, and pooled single muscle fibers. RESULTS: Serum CK activity ranged from 255 to 22,265 U/L in horses with PSSM and 133 to 278 U/L in control horses. Muscle CS activity was lower in horses with PSSM, compared with control horses. Muscle G-6-P lactate, ATP, ADP, and AMP concentrations in whole muscle did not change with exercise in any horses. Concentration of IMP increased with exercise in whole muscle, pooled muscle fibers, and single muscle fibers in horses with PSSM. Large variations in ATP and IMP concentrations were observed within single muscle fibers. CONCLUSIONS AND CLINICAL RELEVANCE: Increased IMP concentration without depletion of ATP in individual muscle fibers of horses with PSSM during submaximal exercise indicates an energy imbalance that may contribute to the development of exercise intolerance and rhabdomyolysis.  相似文献   
99.
100.
An experiment was conducted to examine (a) the effects of photoperiod on timing of sexual maturation (b) the relationship between plasma steroid levels, appetite and growth in male and female Atlantic cod (Gadus morhua L.). Wild caught Norwegian coastal cod were subjected to either a 6L/18D photoperiod typical of January at 60° N-(Short day group) or a simulated natural photoperiod (Normal day group) from June 2000 until spawning started. Appetite of individual fish were measured twice weekly, while weight, length and plasma levels of the sex steroids testosterone (T), 11 keto-testosterone (11-KT) and estradiol-17β (E2) were monitored bimonthly. Cod in the Short day group matured 3 months ahead of the cod in the Normal day group and started spawning in early November. Appetite decreased in both sexes 2–3 months prior to spawning in both groups, but this reduction was stronger among males. In both sexes, length growth was reduced concurrently with the appetite loss. Overall, females had significantly higher somatic growth, put relatively less energy into length growth and had developed larger livers compared to males at the time of spawning in the Short day group. Plasma steroid levels increased in both groups throughout the experiment, reaching peak levels of ca 10 ng ml−1 (T) and 15–20 ng ml−1 (11-KT) in males, and 1.5–2 ng ml−1 (T) and 12–18 ng ml−1 (E2) in females at the onset of spawning. Steroid levels increased more rapidly among Short day cod verifying the earlier onset of maturation. These results confirm that photoperiod is a major cue to maturation in cod and imply that the high cost of spawning for females incur differences in appetite between the sexes.  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