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   24篇
  免费   3篇
林业   2篇
农学   1篇
  5篇
综合类   5篇
畜牧兽医   12篇
植物保护   2篇
  2022年   1篇
  2021年   3篇
  2018年   1篇
  2014年   1篇
  2012年   1篇
  2011年   2篇
  2010年   2篇
  2009年   1篇
  2008年   2篇
  2007年   2篇
  2006年   3篇
  2005年   1篇
  2004年   3篇
  2003年   2篇
  2001年   1篇
  1995年   1篇
排序方式: 共有27条查询结果,搜索用时 15 毫秒
1.

Varroa destructor is considered a major reason for high loss rate of Western honey bee (Apis mellifera) colonies. To prevent colony losses caused by V. destructor, it is necessary to actively manage the mite population. Beekeepers, particularly commercial beekeepers, have few alternative treatments other than synthetic acaricides to control the parasite, resulting in intensive treatment regimens that led to the evolution of resistance in mite populations. To investigate the mechanism of the resistance to amitraz detected in V. destructor mites from French and U.S. apiaries, we identified and characterized octopamine and tyramine receptors (the known targets of amitraz) in this species. The comparison of sequences obtained from mites collected from different apiaries with different treatment regimens, showed that the amino acid substitutions N87S or Y215H in the OctβR were associated with treatment failures reported in French or U.S. apiaries, respectively. Based on our findings, we have developed and tested two high throughput diagnostic assays based on TaqMan technology able to accurately detect mites carrying the mutations in this receptor. This valuable information may be of help for beekeepers when selecting the most suitable acaricide to manage V. destructor.

  相似文献   
2.
Thirty Trichoderma strains representing 15 species within the genus have been screened for extracellular production of chitinolytic enzymes in solid substrate fermentation (SSF). T.longibrachiatum IMI 92027 (=ATCC 36838) gave the highest yield (5.0 IU/g dry matter of substrate) after 3 days of fermentation on wheat bran-crude chitin (9:1 mixture) medium. The optimum moisture content (66.7%), chitin content (20%), initial pH of the medium (2-5) and time course (5 d) of SSF were determ…  相似文献   
3.
Embryonic mortality is a significant problem plaguing the hatching success. Its early forms are especially hardly distinguishable from true infertility. Propidium iodide (PI) staining of the germinal disc combined with outer perivitelline layer (OPVL) sperm counting was used for the determination of 'true' fertility of duck eggs in two different experiments: fertility investigation on fresh, unincubated eggs of Hungarian ducks and on incubated eggs of a crossbred, selected as 'infertile' at the 7th day of incubation. Examination of the relationship between OPVL sperm count and fertility seems to be an adequate tool for checking the effectiveness of insemination programmes and the fertilising capacity of poultry spermatozoa. The proportion of fertile eggs was around 50% when the number of OPVL sperm was between 0.1 and 0.2 spermatozoa/mm2. Ninety-nine percent of the eggs containing > 0.3 OPVL sperm/mm2 were fertile and all of the eggs containing < 0.05 sperm/mm2 were infertile. To assure the accuracy of fertility prediction by OPVL sperm counting, PI staining of the germinal disc was used to determine fertility in uncertain cases. Identification of very early embryonic mortality, i.e. that occurring before oviposition, is very difficult. The use of a dissecting microscope for the assessment of real fertility is suitable in most of the cases, while PI staining of the germinal discs proved to be more reliable for detecting very early embryonic death. The combination of the two methods proved to be a useful tool for detecting the 'true' fertility of duck eggs of different breeds.  相似文献   
4.
Four snap bean varieties (green and yellow-podded) were grown in three water supplies (regularly irrigated, deficit-irrigated and non-irrigated) in order to examine the spectral reflectance at leaf and canopy levels, leaf area index (LAI) and their relationships with the yield and nutritional quality at the University of Debrecen, Debrecen, Hungary from 2011 to 2013. Under non-irrigated condition, the plant height decreased, SPAD values were high but LAI and normalized difference vegetation index (NDVI) were low. The difference in SPAD values was higher between the varieties during flowering under non-irrigated condition and it was more pronounced during pod development using deficit irrigation. In dry years, non-irrigated condition SPAD did not correlate with the yield but during pod development it was correlated with the dry matter content of the pods. The relationship of SPAD with protein and crude fiber content of pods was strongly dependent on the cropping years. Under deficit-irrigated condition, NDVI measured during flowering and pod development correlated closely with the yield where a higher NDVI (0.85) predicted either 6 or 9.5 t ha?1 of yield depending on the variety. Under this condition Serengeti variety with green pods was prominent based on the studied traits among the varieties.  相似文献   
5.
Porcine circoviruses (PCV) are widespread in domestic pigs worldwide and there is growing information about the presence of PCV in other suid species. Based on serological studies with sera of wild boars, it was established that PCV1 was present in these animals and antibodies specific to PCV2 were also detected in wild boars living in captivity or in sylvatic areas, both with or without clinical signs of PMWS. Studies including PCV2 genome or antigen detection confirmed the previous findings. This is the first report about the presence of PCV in Transylvanian wild boar populations. Four hundred and sixty-nine samples were collected and grouped according to geographic origin, tested for the presence of PCV DNA using a real-time quantitative polymerase chain reaction assay, and 13.52% of the animals proved to be positive for one or in three cases both of the PCV genotypes. PCV2 was detected in all of the PCV-positive samples.  相似文献   
6.
Even though the respiratory system is one of the most accessible organs for diagnostic testing, it is not always easy to define chronic lower airway disease in the horse. Diagnostic procedures performed by first opinion veterinarians in the field are often restricted to taking the history and performing clinical examination. Respiratory tract endoscopy, tracheal or bronchoalveolar lavage, and blood sampling are sometimes used but other specific ancillary examinations are seldom performed in stable settings. Therefore, our objectives were to evaluate the diagnostic value of different techniques and examination types routinely used in the diagnostic workup of chronic equine lower airway cases in both stable and clinical circumstances. Another aim of this study was to estimate the prevalence of different chronic pulmonary disorders among horses admitted to a Hungarian referral clinic. According to the conditional inference tree method, age of the horse, history, clinical examination, respiratory tract endoscopy, and bronchoalveolar lavage cytology proved to be the most valuable tools to define pathology. It was also concluded that in 22% of cases, more specific ancillary diagnostic modalities, unavailable for the field veterinarian, were needed to establish the final diagnosis. According to our study, the most frequently diagnosed chronic pulmonary disorders in Hungary are of noninfectious origin, principally recurrent airway obstruction. Regardless of the cause, and interestingly including recurrent airway obstruction as well, these diseases occur primarily during the warm months.  相似文献   
7.
Eurasian Soil Science - To investigate the temporal dynamics of CO2 efflux from the soil surface in a temperate cropland and to quantify the effects of soil temperature, soil water content, N...  相似文献   
8.
Abnormally high spiking activity can damage neurons. Signaling systems to protect neurons from the consequences of abnormal discharge activity have been postulated. We generated conditional mutant mice that lack expression of the cannabinoid receptor type 1 in principal forebrain neurons but not in adjacent inhibitory interneurons. In mutant mice,the excitotoxin kainic acid (KA) induced excessive seizures in vivo. The threshold to KA-induced neuronal excitation in vitro was severely reduced in hippocampal pyramidal neurons of mutants. KA administration rapidly raised hippocampal levels of anandamide and induced protective mechanisms in wild-type principal hippocampal neurons. These protective mechanisms could not be triggered in mutant mice. The endogenous cannabinoid system thus provides on-demand protection against acute excitotoxicity in central nervous system neurons.  相似文献   
9.
Journal of Pest Science - Managed honey bees have suffered severe seasonal losses for most of the past 30&nbsp;years, while at the same time there is a growing need for food crop pollination....  相似文献   
10.
Two haploid induction media (190-0 and W14mi) were tested in isolated microspore culture of two triticale (X Triticosecale Wittmack) genotypes. The W14mi medium proved superior for the production of green plantlets in both genotypes. This basic medium (W14) was used to compare two doubled haploid production methods (isolated microspore culture and anther culture) with the same genotypes. The induction of androgenesis was more effective in isolated microspore culture than in anther culture. The number of embryo-like structures was 9.2 times higher in microspore culture (511.0/100 anthers) compared to anther culture (55.5/100 anthers) and the number of regenerant plantlets was also 3.4 times higher (anther culture—20.15/100 anthers; isolated microspore culture—67.6/100 anthers). However, the regenerant plantlets from isolated microspore culture were mainly albinos while predominantly green plantlets were regenerated from anther culture. The production of green plantlets from anther culture (16.8/100 anthers) was 2.9 times higher than from isolated microspore culture (5.8/100 anthers). The efficiency of anther culture was tested with eight winter triticale genotypes. The phenomenon of albinism did not hinder the green plant production in anther culture. Mean green plantlet production was 10.87/100 anthers. This value was two times higher than the number of albinos (5.01/100 anthers) and higher than previously published reports. The anther culture protocol described in this study is an efficient tool for the production of microspore-derived green plantlets in triticale.  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