全文获取类型
收费全文 | 522篇 |
免费 | 32篇 |
专业分类
林业 | 32篇 |
农学 | 13篇 |
96篇 | |
综合类 | 63篇 |
农作物 | 23篇 |
水产渔业 | 12篇 |
畜牧兽医 | 259篇 |
园艺 | 26篇 |
植物保护 | 30篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 21篇 |
2020年 | 8篇 |
2019年 | 21篇 |
2018年 | 15篇 |
2017年 | 17篇 |
2016年 | 12篇 |
2015年 | 16篇 |
2014年 | 19篇 |
2013年 | 17篇 |
2012年 | 37篇 |
2011年 | 51篇 |
2010年 | 18篇 |
2009年 | 23篇 |
2008年 | 40篇 |
2007年 | 31篇 |
2006年 | 23篇 |
2005年 | 37篇 |
2004年 | 33篇 |
2003年 | 17篇 |
2002年 | 18篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 5篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 2篇 |
1983年 | 11篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1972年 | 2篇 |
1966年 | 1篇 |
1964年 | 1篇 |
1963年 | 2篇 |
1962年 | 1篇 |
1956年 | 1篇 |
排序方式: 共有554条查询结果,搜索用时 15 毫秒
61.
AbstractAIMS: To identify and describe culture and antimicrobial resistance (AMR) patterns in bacteria isolated from canine urinary samples submitted to a New Zealand veterinary diagnostic laboratory.METHODS: Records from a veterinary diagnostic laboratory were examined for bacterial isolates cultured from canine urine samples between January 2005 and December 2012. Culture and susceptibility results were compiled with information on the age, sex and breed of dog. Repeat submissions were removed. Susceptibility was assessed using results of the Kirby-Bauer disk diffusion method, for a standard panel including amoxicillin-clavulanic acid (AMC), cefovecin (from 2010–2012), cephalothin, clindamycin, enrofloxacin and trimethoprim-sulphonamide (TMS).RESULTS: A total of 5,786 urine samples were submitted for analysis, and 3,135 bacterial isolates were cultured from 2,184 samples. Of these 3,135 isolates, 1,104 (35.2%) were Escherichia coli, 442 (14.1%) were Staphylococcus spp., 357 (11.4%) Proteus mirabilis and 276 (8.8%) were Enterococcus spp. The frequency of culture-positive samples increased with increasing age in both female and male dogs (p<0.001). The percentage of E. coli isolates resistant to AMC and cephalothin increased between 2005 and 2012 (p<0.001), as did resistance to enrofloxacin (p=0.022), but there was no change in resistance to TMS (p=0.696). Enrofloxacin was the antimicrobial with the least resistance shown by the four most common bacteria isolated during the course of the study.CONCLUSIONS AND CLINICAL RELEVANCE: The results of this study provide important regional information regarding the prevalence of bacterial uropathogens and their susceptibility patterns. There was an increase in resistance to some commonly used antimicrobials in the treatment of urinary tract infections. Having access to regional antimicrobial susceptibility results is crucial when forming guidelines for the use of antimicrobials for the treatment of urinary tract infections. Given changes in practising habits and antimicrobial usage over time, ongoing monitoring and surveillance of resistance in pathogens is needed. 相似文献
62.
Physiological Responses of Contrasting Rice Genotypes to Salt Stress at Reproductive Stage 总被引:1,自引:0,他引:1
Maria Elisa B.GERONA Marjorie P.DEOCAMPO James A.EGDANE Abdelbagi M.ISMAIL Maribel L.DIONISIO-SESE 《水稻科学》2019,26(4):207-219
Salinity is a major abiotic stress affecting plant growth and productivity. Considerable genetic variation is present in rice in response to salt stress, with higher sensitivity during early seedling and reproductive stage. In this study, physiological changes in leaves and developing panicles of rice genotypes(IR686, Sadri, Rc222, CSR28, IR670 and Pokkali) contrasting in salt tolerance at the reproductive stage were evaluated in greenhouse experiment under salt stress. The results showed that IR670 and the tolerant-check Pokkali maintained lower Na~+/K~+ ratio, less reduction in chlorophyll concentration, lower malondialdehyde(MDA) production, higher concentrations of reduced ascorbate(reduced AsA), higher proline accumulation and lower percentage reduction in pollen viability than the salt-sensitive genotypes under salt stress. The higher concentration of reduced AsA suggests an efficient ROS-scavenging system. Physiological measurements and pollen viability analysis revealed that Sadri(moderately tolerant at the seedling stage) is sensitive to salt stress at the flowering stage. The findings will be useful in breeding salt tolerant varieties at both seedling and reproductive stages by selecting appropriate genotypes and phenotypes. 相似文献
63.
Guyonnet D Chassany O Picard C Guillemin I Meunier J Seignobos E Vigneux M Lassel T Trudeau E 《Public health nutrition》2008,11(11):1163-1172
64.
With an increasing proportion of natural forests being replaced by plantations, there is a need to determine their potential to fulfill ecological purposes other than wood production. This study evaluated the extent to which deciduous and coniferous plantations develop understory attributes comparable to those of naturally regenerated stands. A functional group approach was used to synthesise species responses in terms of their ecological traits. Multivariate analyses of ecological traits revealed 16 emergent groups that shared common traits associated with a similar life history strategy. Responses of these groups, understory structure, and understory environmental conditions to plantation types and stand stages were analyzed and compared to naturally regenerated stands. Clear associations of trait responses to stand developmental stages and plantation types emerged. Light-demanding and wind-dispersed species groups were associated with early-successional stages, while woody groups, ferns and ant-dispersed spring-flowering herbs were associated with late-successional stages. Analyses also revealed an indicator group associated with old naturally regenerated forest. The understory functional groups and environmental conditions of deciduous plantations converged toward those of old naturally regenerated forests. However, understory structure in deciduous plantations remained poorly developed and richness of the indicator group was low compared to unplanted stands. Conifer plantations, currently the most common plantation type in the northern hardwood biome, showed a completely different pathway of understory development. Modifications to current plantation management practices are proposed to help recreate or maintain natural understory biological and physical attributes. 相似文献
65.
Isabelle Le Viol Romain Julliard Louis de Redon Nathalie Machon 《Biological conservation》2008,141(6):1581-1590
Road verges should play a crucial role as a refuge for native flora and fauna in human dominated landscapes. However, the influence of construction choices, such as plantation of woody species, on the biodiversity supported by roadsides has received little attention, although the presence of hedgerows in roadsides is likely to enhance their role as a refuge, notably for woodland species. Using standardised methods, we assessed the impact of planted hedgerows on two taxonomic groups (plants and spiders) inhabiting highway verges within an intensive agricultural landscape. We examined community richness, taxonomic and functional composition in sites with and without planted hedgerows. At the site level, the response of plant and spider communities to the presence of planted hedgerows differed markedly: hedgerows were associated with significantly higher plant richness (higher α-diversity), but similar spider richness. Plant communities in sites without hedgerows appeared as a subset of communities in sites with hedgerows, whereas spider communities in non-planted sites were complementary to that of planted sites (increased β-diversity). The presence of planted hedgerows was also associated with increased taxonomic and functional trait diversity at the landscape level (γ-diversity), through an increased β-diversity in both plants and spiders. Our results thus suggest that a mosaic of planted hedgerows and grassland habitats is crucial for the maintenance of biodiversity at a landscape scale. By providing information for road practitioners and policy makers regarding their potential impact on biodiversity, these results have important direct implications for the management of road networks. 相似文献
66.
霉菌毒素是由生长在动物饲料和人类食品上的真菌所产生的结构各异的二级代谢产物.动物摄入中等至高剂量霉菌毒素引起的临床中毒综合征已有详细描述. 相似文献
67.
68.
A 3-month-old English Cocker Spaniel and a 6-month-old miniature poodle presented with clinical signs related to an abnormal right eye since birth. In both dogs, the right globe could not be identified and was replaced by a fluctuant intraorbital mass covered by a vascularized mucous membrane. Ultrasonography demonstrated that both masses were cystic structures markedly larger in size than the normal contralateral globes. In both cases, surgical excision revealed a multilobular cyst filling the whole orbital cavity. Histopathologic examination and immunostaining for glial fibrillary acid protein and S100 protein supported a diagnosis of neural cysts associated with ocular dysplasia. The definitive diagnosis was congenital cystic eye and microphthalmos with cyst for the Cocker Spaniel and miniature poodle, respectively. Karyotype was normal in both dogs. Congenital cystic eye and microphthalmos with cyst result from defects in early embryonic life that arise following formation of the optic vesicle and prior to closure of the optic fissure. To the authors' knowledge neither has been reported in the canine species. They should be considered in the differential diagnosis of orbital cysts in dogs. 相似文献
69.
Martina Mosing Dr med vet DECVAA Isabelle K. Iff Dr med vet DECVAA Wolfgang Nemetz MD 《Journal of Veterinary Emergency and Critical Care》2008,18(5):532-536
Objective – To describe general anesthesia and successful resuscitation of a dog developing asystole and apnea during extradural injection of local anesthetic and an opioid. Case Summary – A Beagle with a ruptured cranial cruciate was premedicated with acepromazine and methadone. Anesthesia was induced with propofol and, after endotracheal intubation, maintained using isoflurane in oxygen. During extradural injection of a mixture of lidocaine, bupivacaine, and morphine the dog developed apnea and asystole. Cardiopulmonary cerebral resuscitation was started promptly and the dog was successfully resuscitated. New Information Provided – Asystole and apnea are possible serious side effects of extradural anesthesia in dogs. With adequate monitoring and early detection successful resuscitation is possible. 相似文献
70.
Clinical features of canine pulmonary veno‐occlusive disease and pulmonary capillary hemangiomatosis