全文获取类型
收费全文 | 449篇 |
免费 | 29篇 |
专业分类
林业 | 31篇 |
农学 | 22篇 |
130篇 | |
综合类 | 19篇 |
农作物 | 24篇 |
水产渔业 | 11篇 |
畜牧兽医 | 194篇 |
园艺 | 11篇 |
植物保护 | 36篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 18篇 |
2020年 | 22篇 |
2019年 | 15篇 |
2018年 | 14篇 |
2017年 | 22篇 |
2016年 | 23篇 |
2015年 | 24篇 |
2014年 | 21篇 |
2013年 | 41篇 |
2012年 | 43篇 |
2011年 | 28篇 |
2010年 | 25篇 |
2009年 | 15篇 |
2008年 | 31篇 |
2007年 | 24篇 |
2006年 | 21篇 |
2005年 | 17篇 |
2004年 | 12篇 |
2003年 | 10篇 |
2002年 | 13篇 |
2001年 | 4篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有478条查询结果,搜索用时 281 毫秒
461.
Loeffler A Linek M Moodley A Guardabassi L Sung JM Winkler M Weiss R Lloyd DH 《Veterinary dermatology》2007,18(6):412-421
Resistance to cephalosporins and/or fluoroquinolones by Staphylococcus intermedius has remained low in Europe, with effective drugs generally available for systemic therapy in pets. However, multiresistant, mecA-positive S. intermedius isolated from dogs and cats is now emerging in Europe. Twelve S. intermedius isolates, highly resistant to at least five antimicrobial classes, were isolated from skin and ear infections in 11 dogs and a cat. The 12 isolates represented 23% of all S. intermedius submissions from one veterinary dermatology referral clinic in northern Germany to veterinary diagnostic laboratories during an 18-month period and resistance included cefalexin, methicillin and enrofloxacin. The animals had been referred to the clinic with recurrent superficial pyoderma, deep pyoderma, pododermatitis or chronic otitis, all unresponsive to systemic beta-lactam-antibiotics or fluoroquinolones. Infection resolved in 10 dogs and the cat on a combination of antimicrobial treatment and correction of underlying causes. Four dogs and a cat required systemic and topical therapy; in six dogs topical antimicrobial therapy alone was successful. Phenotypic and genotypic characteristics of the S. intermedius isolates were determined; species identification was confirmed by polymerase chain detection of thermonuclease genes (nuc) and the presence and expression of the gene conferring resistance to all beta-lactam antibiotics (mecA) were demonstrated in all; based on pulsed-field gel electrophoresis, six were indistinguishable, the others closely or possibly related. The emergence of multiresistant, mecA-positive S. intermedius in Europe is alarming. Zoonotic implications, awareness among veterinary laboratories and strategies for the use of antimicrobials in small animal practice need to be considered. 相似文献
462.
Ivens AC Peacock CS Worthey EA Murphy L Aggarwal G Berriman M Sisk E Rajandream MA Adlem E Aert R Anupama A Apostolou Z Attipoe P Bason N Bauser C Beck A Beverley SM Bianchettin G Borzym K Bothe G Bruschi CV Collins M Cadag E Ciarloni L Clayton C Coulson RM Cronin A Cruz AK Davies RM De Gaudenzi J Dobson DE Duesterhoeft A Fazelina G Fosker N Frasch AC Fraser A Fuchs M Gabel C Goble A Goffeau A Harris D Hertz-Fowler C Hilbert H Horn D Huang Y Klages S Knights A Kube M Larke N Litvin L Lord A 《Science (New York, N.Y.)》2005,309(5733):436-442
463.
Rahmatalla Siham A. Arends Danny Ahmed Ammar Said Reissmann Monika Brockmann Gudrun A. 《Tropical animal health and production》2020,52(3):1211-1222
Tropical Animal Health and Production - The aim of the present study was to assess genetic variation that is characteristic for Sudanese goat breeds in the milk whey protein genes (LALBA and BLG).... 相似文献
464.
Patrycja Mrowiec Monika Bugno-Poniewierska Wiesława Młodawska 《Reproduction in domestic animals》2021,56(2):199-207
Taking into account the latest Red List of the International Union for Conservation of Nature in which 25% of all mammals are threatened with extinction, somatic cell nuclear transfer (SCNT) could be a beneficial tool and holds a lot of potential for aiding the conservation of endangered, exotic or even extinct animal species if somatic cells of such animals are available. In the case of shortage and sparse amount of wild animal oocytes, interspecies somatic cell nuclear transfer (iSCNT), where the recipient ooplasm and donor nucleus are derived from different species, is the alternative SCNT technique. The successful application of iSCNT, resulting in the production of live offspring, was confirmed in several combination of closely related species. When nucleus donor cells and recipient oocytes have been used in many other combinations, very often with a very distant taxonomical relation iSCNT resulted only in the very early stages of cloned embryo development. Problems encountered during iSCNT related to mitochondrial DNA (mtDNA)/genomic DNA incompatibility, mtDNA heteroplasmy, embryonic genome activation of the donor nucleus by the recipient oocyte and availability of suitable foster mothers for iSCNT embryos. Implementing assisted reproductive technologies, including iSCNT, to conservation programmes also raises concerns that the production of genetically identical populations might cause problems with inbreeding. The article aims at presenting achievements, limitations and perspectives of iSCNT in maintaining animal biodiversity. 相似文献
465.
Ueli Braun Colin Schwarzwald Stefanie Ohlerth Sandra Frei Monika Hilbe 《Acta veterinaria Scandinavica》2014,56(1):14
Background
Three Brown Swiss cows with abnormal regurgitation because of a perioesophageal disorder are described.Case presentation
The cows were ill and had poor appetite, salivation and regurgitation of poorly-chewed feed. Collection of rumen juice was successful in one cow, and in another, the tube could be advanced to the level of the 7th intercostal space, and in the third, only saliva could be collected. In one cow, oesophagoscopy revealed a discoloured 10-cm mucosal area with fibrin deposits. Thoracic radiographs were normal. The cows were euthanased and examined postmortem. Cow 1 had a large perioesophageal abscess containing feed material at the level of the thoracic inlet, believed to be the result of a healed oesophageal injury. Cow 2 had an abscess between the oesophagus and trachea 25 cm caudal to the epiglottis with the same presumed aetiology as in cow 1. Cow 3 had a mediastinal carcinoma that enclosed and constricted the oesophagus.Conclusions
Abnormal regurgitation in cattle is usually the result of an oesophageal disorder. Causes of oesophageal disorders vary widely and their identification can be difficult. 相似文献466.
Andrej Koleno Jan fluba Zuzana Krupova Monika Michalickova Ondrej Debreceni 《农业科学与技术》2014,(1):93-101
The aim of this study was to analyse the most important factors affecting the profitability of suckler cows herds in Slovakia in 2010. The economic models were used to verify whether the suckler cows farming is profitable without subsidies in the current production conditions in Slovakia as well as their optimal location in the agricultural natural conditions of Slovakia from the perspective of economic efficiency. The breeding of cattle, mainly for the beef meat production, has long been unprofitable as it is apparent also from the analysis of several studies. In the model without inclusion of subsidies, it was calculated that the suckler cows farming is unprofitable at the current production parameters and realization prices of calves. The losses per cow and year were ranged from -240ε in the model by using a combination of the maximum threshold values of input parameters to -818ε by using a combination of the minimum threshold values of the input parameters. In the models including of subsidies amount of loss and/or profit per cow and year varied depending on the input parameters mainly on natality, average daily gain, the realization price of calves and the level of subsidies provided to breeder as well. The economic results are ranged from -277ε to 724ε per cow and year. From economical as well as production point of view, the most appropriate agricultural natural regions for suckler cows farming in Slovakia are upland and highland regions. 相似文献
467.
Monika Krzewska Ilona Czyczyło-Mysza Ewa Dubas Gabriela Gołębiowska-Pikania Iwona Żur 《Euphytica》2015,206(1):263-278
468.
Genetic Mapping of QTLs for Tissue-Culture Response in Plants 总被引:1,自引:0,他引:1
Summary Plant regeneration from cultured tissues has been shown to be under genetic control in a number of plant species. Using quantitative trait loci (QTL) mapping technology, it has become possible to estimate the number of loci controlling genetic variation and to characterize their map position in the genome. With the use of different types of mapping populations such as recombinant inbred lines (RIL), F2 or doubled haploids (DH) it was possible to detect QTLs for tissue culture response (TCR). For the evaluation of TCR numerous parameters describing induction and regeneration steps were applied. However, the lack of consistency with respect to parameters used by different researchers sometimes makes comparisons between QTL studies complicated. Another problem frequently present in works dealing with QTLs for TCR is skewed distributions of the traits used for evaluating tissue culture capability, usually interpreted as the indication of a presence of major genes. The majority of QTL analyses of TCR-traits were conducted with monocots – rice, barley and maize. The number of QTLs detected for a particular characteristic of tissue culture capability ranged from 1 to 8. The percentage of phenotypic variation explained by a single QTL varied from 2.7 to 65.4%, with the values between ca. 6 and ca. 26 % being more common. Determination of molecular markers linked to a QTL of TCR provides valuable tools for biotechnological approaches aimed at improving plant regeneration capability. 相似文献
469.
Claudia Bachofen Hans-Rudolf Vogt Hanspeter Stalder Tanja Mathys Reto Zanoni Monika Hilbe Matthias Schweizer Ernst Peterhans 《Veterinary research》2013,44(1):32
Bovine viral diarrhoea virus (BVDV) is an economically important pathogen of cattle worldwide. Infection of a pregnant animal may lead to persistent infection of the foetus and birth of a persistently infected (PI) calf that sheds the virus throughout its life. However, BVD viruses are not strictly species specific. BVDV has been isolated from many domesticated and wild ruminants. This is of practical importance as virus reservoirs in non-bovine hosts may hamper BVDV control in cattle. A goat given as a social companion to a BVDV PI calf gave birth to a PI goat kid. In order to test if goat to goat infections were possible, seronegative pregnant goats were exposed to the PI goat. In parallel, seronegative pregnant goats were kept together with the PI calf. Only the goat to goat transmission resulted in the birth of a next generation of BVDV PI kids whereas all goats kept together with the PI calf aborted. To our knowledge, this is the first report which shows that a PI goat cannot only transmit BVD virus to other goats but that such transmission may indeed lead to the birth of a second generation of PI goats. Genetic analyses indicated that establishment in the new host species may be associated with step-wise adaptations in the viral genome. Thus, goats have the potential to be a reservoir for BVDV. However, the PI goats showed growth retardation and anaemia and their survival under natural conditions remains questionable. 相似文献
470.
Andreas Fließbach Monika Messmer Bruno Nietlispach Valentina Infante Paul Mäder 《Biology and Fertility of Soils》2012,48(3):315-324
Genetically modified (GM) maize containing genes from the soil bacterium Bacillus thuringiensis (Bt) was cultivated on 29% of the total maize production area worldwide in 2009. Most studies to date compare Bt-maize varieties with their near isogenic lines; however, there is little information on the variability of conventional maize
breeding lines and how the effects of Bt varieties are ranked within. In our study on the potential risks of Bt-maize varieties, we analyzed tissue quality and compared the effects of ten conventional and GM maize varieties on soil microbiological
properties in a replicated climate chamber experiment. All maize varieties were cultivated twice in the same soil microcosm.
Shoot yields and soluble C in leaf tissue of Bt varieties were higher than the ones of non-Bt. Soil dehydrogenase activity was reduced by 5% under Bt varieties compared to non-Bt, while most of the other soil microbial properties (soil microbial biomass, basal respiration) showed no significant differences
between Bt and non-Bt varieties. The leaves and roots of one Bt variety were decomposed to a greater extent than the ones of its near isogenic line; the conventional breeding lines also
showed higher values. Changes in crop and soil parameters were found when comparing the first and the second crops, but the
effects of repeated cropping were the same for all tested varieties. For the studied parameters, the variation among non-Bt-maize varieties was similar to the difference between Bt and non-Bt varieties. 相似文献