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   402篇
  免费   23篇
林业   23篇
农学   6篇
基础科学   4篇
  147篇
综合类   16篇
农作物   10篇
水产渔业   15篇
畜牧兽医   173篇
园艺   7篇
植物保护   24篇
  2023年   1篇
  2022年   6篇
  2021年   11篇
  2020年   18篇
  2019年   8篇
  2018年   7篇
  2017年   14篇
  2016年   16篇
  2015年   13篇
  2014年   17篇
  2013年   23篇
  2012年   30篇
  2011年   49篇
  2010年   32篇
  2009年   20篇
  2008年   26篇
  2007年   25篇
  2006年   21篇
  2005年   13篇
  2004年   26篇
  2003年   10篇
  2002年   11篇
  2001年   5篇
  2000年   2篇
  1999年   6篇
  1997年   2篇
  1996年   3篇
  1995年   2篇
  1994年   3篇
  1992年   1篇
  1991年   2篇
  1990年   2篇
排序方式: 共有425条查询结果,搜索用时 15 毫秒
1.
West Nile virus lineage 2 (WNV‐2) was detected in the brain of 17 goshawks (Accipiter gentilis) that succumbed to neuroinvasive disease in the Czech Republic during 2018: twelve birds were captive and five wild. Furthermore, two wild sparrowhawks (Accipiter nisus) and three other captive birds of prey (golden eagle Aquila chrysaetos, hybrid saker falcon Falco cherrug × F. rusticolus and Harris's hawk Parabuteo unicinctus) also died due to WNV encephalitis. The 2018 outbreak in Czech raptors clearly reflects a new epidemiological situation and indicates an increasing risk of both raptor and human infection with WNV‐2 in the country.  相似文献   
2.
Pony Club is one of the leading junior equestrian organisations in the world, and was established to teach young people the many aspects of horsemanship. The aim of this study was to gain an understanding of the health and performance of Pony Club horses from the perspective of their owners. In-depth interviews were conducted with Pony Club members at two sites in Australia, and topics relating to participants' background with horses, horse attributes valued by participants, horse health and performance, and Pony Club-related matters. The in-depth interviews were taped, transcribed and analysed, by describing the themes and issues recorded in the dialogue and conducting cross-case analysis (finding similarities and dissimilarities between participants with respect to each of the above-mentioned topics). A total of 32 interviews were conducted. The participants' background with horses varied greatly. The horse attributes valued by > or =59% of participants included temperament, size, ability and suitability for riders. A range of issues relating to health and performance were important to > or =53% of participants, including horse temperament, nutrition, internal parasites, lameness and foot-care, and colic. Soundness and preventive health measures were rarely mentioned (< or =16% of participants). Friends or knowledgeable horse people were identified as the first point of contact for horse-health matters, and veterinarians were only used as a last resort or for serious problems. Members of Pony Club learned about their horses by trial and error. Optimal performance was described as a horse that was willing to do as the rider asked. Poor performance was usually the result of the horse misbehaving, and could include a resistance to rider commands, pigrooting and bucking.  相似文献   
3.
4.
Atropine, an anticholinergic agent commonly used in human and veterinary medicine, is reported to cause toxicity associated with its antimuscarinic action. A juvenile pygmy sperm whale, Kogia breviceps, was treated with atropine in an attempt to relieve symptoms similar to pyloric stenosis, as has been used in humans. Two doses of 0.01 mg/kg were given i.m., 12 hr apart, followed by three doses of 0.005 mg/kg i.m. s.i.d. over the next 3 days. Symptoms associated with atropine toxicity developed gradually and included hyperexcitability, a generalized ascending paralysis of body musculature, shallow, rapid respiration, vomiting, aspiration of seawater, and pulmonary edema. Treatment with physostigmine salicylate (two doses of 2 mg i.m., I hr apart) was effective in counteracting the paralysis, as well as other symptoms, beginning in as little as 17 min after the first dose, and the whale was back to swimming on its own after 8 hr. All overt symptoms of atropine toxicity were gone in about 24 hr, but there were other possible sequella that lasted much longer.  相似文献   
5.
The species of pets owned in the Netherlands are constantly changing, and it is important that veterinary practitioners have information about the number and species of pets presented in veterinary practice. Using the same methodology as in 1994, we determined the relative importance of the various pet species in 2005 and compared these data with those for 1994. The most notable findings were a 25% increase in the number of birds and exotic animals seen in small and large animal practices (from about 10% to about 12.5%), a doubling of the number of birds and tripling of the number of pigeons seen in mixed practices, a doubling of the number of reptiles seen in small animal practices, and a 10-fold increase in the number of fish seen in veterinary practices in general. There was a significant decrease in the proportion of cats (from 46% to 40.7%) and an increase in the proportion of dogs (from 44% to 46.7%). These trends in veterinary practice consultations did not parallel those seen in pet ownership. The increase in the number of birds (especially pigeons), reptiles, and fish seen in veterinary practice emphasizes the need to pay attention to these species in the standard companion animal curriculum.  相似文献   
6.
Several hydrolysate-based diets have been commercialized for helping diagnose or treat dogs with cutaneous adverse food reactions (CAFR). This systematic review was performed to examine the evidence in favour of reduced immunological and clinical allergenicity of hydrolysates in dogs with CAFR. Citation databases, meeting abstracts and article bibliographies were scanned for relevant citations, and companies were contacted to provide unpublished reports. Eleven studies relevant to this study were identified. Some evidence of reduced serum IgE binding to a soy hydrolysate (1 study) and decreased intradermal test reactivity to hydrolysed proteins (three studies) was found. In four reports, the feeding of dogs suspected of having CAFR with hydrolysate-based diets reduced or eliminated clinical signs in a variable proportion of subjects. The percentage of dogs with CAFR that still reacted to these hydrolysate-based diets could not be assessed, however. Importantly, up to 50% of dogs with CAFR enrolled in three controlled studies exhibited increases in clinical signs after ingesting partial hydrolysates derived from foods to which they were hypersensitive. In conclusion, the limited number of studies undertaken point to reduced – but not eliminated – immunological and clinical allergenicity of hydrolysate-based commercial diets. A variable proportion of dogs with CAFR will exhibit a worsening of clinical signs when fed partial hydrolysates. Clinicians must weigh the clinical benefit of these diets versus their high cost and low risk of reduced appetence or gastrointestinal sign development. At this time, hydrolysate-containing diets are probably best used in dogs suspected not to be hypersensitive to their individual components.  相似文献   
7.
Blood cell morphology and count are not uniform across species. Recently, between‐species comparisons revealed that the size of red blood cells is associated with body size in some lizard taxa, and this finding was interpreted in the context of the metabolic theory. In the present study, we examined the numbers and the size of blood cells in 2 species of monitor lizards, the mangrove‐dwelling monitor (Varanus indicus) and the savannah monitor (V. exanthematicus), and we compared these traits in individuals of different body size. The results revealed that during the course of ontogeny, the size of red blood cells increases with body mass. Because the mass‐specific metabolic rate decreases with body size and the cell volume‐to‐surface ratio decreases with the cell size, changes in the erythrocyte size might be the result of oxygen transport adjustment.  相似文献   
8.
According to current scientific opinion the risk of human infection with H5N1 via preparation and consumption of poultry meat is negligible.This opinion has not yet been challenged by a formal risk assessment, due to the lack of empirical data. We have developed a scenario pathway model as a conceptual framework for a formal assessment of the H5N1 risk to humans through consumption of poultry meat and parameterise the model using information derived from expert opinions. The aim of this study was to investigate whether the notion of an overall negligible risk via the oral infection route is consistent with ad hoc data and expert opinions on the relevant parameters of the model.The model is mainly based on expert opinion. A stochastic Monte-Carlo simulation was conducted which took into consideration (amongst others) the exposure and infection of chicken (broiler and layer), turkeys, ducks and geese, the probabilities of detection prior to slaughter, virus survival and contamination during slaughter, as well as during the cutting and preparation of meat in commercial plants and in private households, respectively. The empirical consumption pattern for poultry meat in Germany was taken into account in the simulation.The results show that the risk for the individual consumer is practically zero whereas up to 23 cases per year in Germany might occur if the upper (more pessimistic) ranges of the expert opinions apply.The finding of a low but non-negligible risk to the population is discussed in relation to the epidemiological information available from recent outbreaks in South East Asia.  相似文献   
9.
OBJECTIVE: To compare the perioperative stress response in dogs administered medetomidine or acepromazine as part of the preanesthetic medication. ANIMALS: 42 client-owned dogs that underwent elective ovariohysterectomy. PROCEDURE: Each dog was randomly allocated to receive medetomidine and butorphanol tartrate (20 microgram/kg and 0.2 mg/kg, respectively, IM) or acepromazine maleate and butorphanol (0.05 and 0.2 mg/kg, respectively, IM) for preanesthetic medication. Approximately 80 minutes later, anesthesia was induced by administration of propofol and maintained by use of isoflurane in oxygen. Each dog was also given carprofen before surgery and buprenorphine after surgery. Plasma concentrations of epinephrine, norepinephrine, cortisol, and beta-endorphin were measured at various stages during the perioperative period. In addition, cardiovascular and clinical variables were monitored. RESULTS: Concentrations of epinephrine, norepinephrine, and cortisol were significantly lower for dogs administered medetomidine. Concentrations of beta-endorphin did not differ between the 2 groups. Heart rate was significantly lower and mean arterial blood pressure significantly higher in dogs administered medetomidine, compared with values for dogs administered acepromazine. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that for preanesthetic medications, medetomidine may offer some advantages over acepromazine with respect to the ability to decrease perioperative concentrations of stress-related hormones. In particular, the ability to provide stable plasma catecholamine concentrations may help to attenuate perioperative activation of the sympathetic nervous system.  相似文献   
10.
Objective A meibometer is a device to measure the delivery rate of lipids on the eyelid margin. The aim of this study is to determine the measuring precision of the new Meibometer® MB550 (Courage-Khazaka electronic GmbH, 50829, Cologne, Germany), linked to a computer, by means of repeated measurements in dogs by different examiners. Procedure Two investigators measured the lipid rate on the eyelid margin in 10 healthy dogs for 10 days. One examiner measured the right eye (OD) and the other measured the left eye (OS) for 5 days. After 5 days, the eyes to be measured were switched between the examiners. The new device was able to record all measurement values as charts and curves in comparison to the previous Meibometer, which displayed only one value. Results Mean meibomium lipid level ± SD in the OD and OS of 10 dogs in 10 days was 211 ± 48 MU and 205 ± 41 MU (meibometer units), respectively. There was no significant difference between OD and OS, but a broad distribution of the values could be found. Gender did not influence the measurements. A significant difference was determined between the measurements in the first 5 days to those in the following 5 days. There was, therefore, also a significant difference in the measurements of the 2 examiners. Conclusion Meibometry is a minimally invasive lipid measuring method on the eyelid margin. Repeated measurement results obtained by two examiners, with the new device Meibometer MB550 linked to a computer, showed a wide range of values. The measuring precision of the new Meibometer MB550 is therefore questionable.  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