全文获取类型
收费全文 | 637篇 |
免费 | 36篇 |
国内免费 | 1篇 |
专业分类
林业 | 12篇 |
农学 | 8篇 |
基础科学 | 1篇 |
68篇 | |
综合类 | 89篇 |
农作物 | 24篇 |
水产渔业 | 22篇 |
畜牧兽医 | 399篇 |
园艺 | 5篇 |
植物保护 | 46篇 |
出版年
2023年 | 4篇 |
2021年 | 5篇 |
2020年 | 7篇 |
2019年 | 11篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 14篇 |
2015年 | 7篇 |
2014年 | 18篇 |
2013年 | 22篇 |
2012年 | 26篇 |
2011年 | 38篇 |
2010年 | 13篇 |
2009年 | 20篇 |
2008年 | 22篇 |
2007年 | 30篇 |
2006年 | 26篇 |
2005年 | 24篇 |
2004年 | 14篇 |
2003年 | 25篇 |
2002年 | 25篇 |
2001年 | 28篇 |
2000年 | 22篇 |
1999年 | 23篇 |
1998年 | 4篇 |
1997年 | 8篇 |
1996年 | 7篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1992年 | 14篇 |
1991年 | 9篇 |
1990年 | 10篇 |
1989年 | 19篇 |
1988年 | 7篇 |
1987年 | 10篇 |
1986年 | 7篇 |
1983年 | 5篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1973年 | 3篇 |
1972年 | 7篇 |
1971年 | 5篇 |
1970年 | 7篇 |
1969年 | 7篇 |
1968年 | 10篇 |
1967年 | 4篇 |
1966年 | 3篇 |
1934年 | 4篇 |
排序方式: 共有674条查询结果,搜索用时 31 毫秒
111.
Gabriele Vaccari Cynthia H. Panagiotidis Cristina Acin Simone Peletto Francis Barillet Pierluigi Acutis Alex Bossers Jan Langeveld Lucien van Keulen Theodoros Sklaviadis Juan J. Badiola Olivier Andr��oletti Martin H. Groschup Umberto Agrimi James Foster Wilfred Goldmann 《Veterinary research》2009,40(5)
Scrapie is a fatal, neurodegenerative disease of sheep and goats. It is also the earliest known member in the family of diseases classified as transmissible spongiform encephalopathies (TSE) or prion diseases, which includes Creutzfeldt-Jakob disease in humans, bovine spongiform encephalopathy (BSE), and chronic wasting disease in cervids. The recent revelation of naturally occurring BSE in a goat has brought the issue of TSE in goats to the attention of the public. In contrast to scrapie, BSE presents a proven risk to humans. The risk of goat BSE, however, is difficult to evaluate, as our knowledge of TSE in goats is limited. Natural caprine scrapie has been discovered throughout Europe, with reported cases generally being greatest in countries with the highest goat populations. As with sheep scrapie, susceptibility and incubation period duration of goat scrapie are most likely controlled by the prion protein (PrP) gene (PRNP). Like the PRNP of sheep, the caprine PRNP shows significantly greater variability than that of cattle and humans. Although PRNP variability in goats differs from that observed in sheep, the two species share several identical alleles. Moreover, while the ARR allele associated with enhancing resistance in sheep is not present in the goat PRNP, there is evidence for the existence of other PrP variants related to resistance. This review presents the current knowledge of the epidemiology of caprine scrapie within the major European goat populations, and compiles the current data on genetic variability of PRNP. 相似文献
112.
JR Rodriguez-Sosa JD Silvertown RA Foster JA Medin A Hahnel 《Reproduction in domestic animals》2009,44(4):612-620
Spermatogonial transplantation will provide a new way to study spermatogenesis in domestic animals, disseminate male genetics and produce transgenic animals, if efficiency can be improved. We evaluated a 'surgical' method for transplanting donor cells into testes of ram lambs, where the head of the epididymis is reflected, and a catheter introduced into the extra-testicular rete testis. We also tested transduction of ram spermatogonia with a lentiviral (LV) vector as a means to identify permanent colonization, and introduce genes into donor cells. Eight ram lambs, 11- to 13-week olds, were the recipients: in five, spermatogonia were injected into one testis, and the contralateral testis was an un-manipulated control: in two, spermatogonia were injected into one testis and the contralateral was sham-injected: in one, both testes were injected. Six lambs received spermatogonia labelled with a cell-tracking dye and these were collected 1 or 2 weeks after transplantation; three lambs received spermatogonia transduced with a LV vector driving the expression of enhanced Green Fluorescence Protein and these were collected after 2 months. Donor cells were detected by immunohistochemistry in tubules of seven of nine recipient testes. Approximately 22% of tubule cross-sections contained donor cells immediately after transplantation, and 0.2% contained virally transduced cells 2 months after transplantation. The onset of spermatogenesis was delayed, and there were lesions in both injected and sham-injected testes. Despite the effects of the surgery, elongated spermatids were present in one recipient testis 2 months after surgery. The results suggest that, after modifying the surgical and transduction techniques, this approach will be a means to produce good colonization by donor spermatogonia in sheep testes. 相似文献
113.
114.
J. Scott Weese Roberta Poma Fiona James Gilbert Buenviaje Robert Foster Durda Slavic 《The Canadian veterinary journal. La revue veterinaire canadienne》2009,50(6):655-656
Staphylococcus pseudintermedius was implicated as the cause of rapidly progressive and fatal necrotizing fasciitis in a dog. The isolate was methicillin-susceptible and did not contain genes encoding the Panton-Valentine leukocidin. While Streptococcus canis is typically considered to be the main cause of necrotizing fasciitis in dogs, staphylococci should also be considered. 相似文献
115.
Twenty-one clones of the peach-potato aphid, Myzus persicae (Sulzer), carrying various combinations of known mechanisms of insecticide resistance were assessed for their response to the new pyridine azomethine compound, pymetrozine, in leaf-dip bioassays. Pymetrozine was also applied as a foliar spray to populations of four different UK M persicae clones on potato plants in field-simulator chambers. Neither study showed any evidence of cross-resistance to this compound. Pymetrozine, used in conjunction with other effective aphicides, such as pirimicarb and imidacloprid, can therefore play an important role in insecticide resistance-management strategies for M persicae. 相似文献
116.
Foster AP Naylor RD Howie NM Nicholas RA Ayling RD 《Veterinary journal (London, England : 1997)》2009,179(3):455-457
Signs of severe otitis media in 20% of dairy calves on one farm were associated with Mycoplasma bovis infection, based on isolation from the external ear canal and nares. Affected calves seroconverted to M. bovis and no other significant bacteria were isolated. Infection was considered likely to have originated from cows in the milking herd based on evidence of seroconversion and detection of infection in a milk sample. M. bovis infection should be considered when investigating otitis problems in calves. 相似文献
117.
118.
BACKGROUND: Although there are still no confirmed reports of strong resistance to neonicotinoid insecticides in aphids, the peach-potato aphid (Myzus persicae Sulzer) shows variation in response, with some clones exhibiting up to tenfold resistance to imidacloprid. Five clones varying in response to imidacloprid were tested with four other neonicotinoid molecules to investigate the extent of cross-resistance.RESULTS: All four compounds-thiamethoxam, thiacloprid, clothianidin and dinotefuran-were cross-resisted, with ED(50) values ranked in the same order as for imidacloprid. Resistance factors ranged up to 11 for imidacloprid, 18 for thiamethoxam, 13 for thiacloprid, 100 for clothianidin and 6 for dinotefuran.CONCLUSION: This variation in response does not appear to be sufficient to compromise the field performance of neonicotinoids aimed at controlling aphids. However, it highlights the need for careful vigilance and stewardship in all M. persicae populations, and a need to consider neonicotinoids as a single cross-resisted group for management purposes. 相似文献
119.
120.
Palatability and anthelmintic activity of chicory (Cichorium intybus L.) forage are influenced by the sesquiterpene lactones lactucin (LAC), 8‐deoxylactucin (DOL) and lactucopicrin. Therefore, the objective of this study was to determine how sesquiterpene lactone concentration and composition vary during the growing season. Three forage chicory cultivars (Puna, Forage Feast and Lacerta) grown in West Virginia and Pennsylvania (USA) were managed during two consecutive years to maintain plants in the vegetative stage, and sesquiterpene lactones in leaves were quantified after each growth interval. Cultivars differed in the total concentration of sesquiterpene lactones and in the proportions of LAC and DOL. Total sesquiterpene lactone concentration generally decreased or remained constant during the season, but the specific response depended on the cultivar. Differences in seasonal patterns between years corresponded with unusual climatic conditions. The three cultivars had similar concentrations of DOL in the spring. Forage Feast provided a dramatically lower concentration of DOL during the summer. Uniformly high concentrations of DOL across the growing season in Puna and Lacerta make these cultivars attractive for use in bioactive pastures for control of Haemonchus contortus. Changes in both sesquiterpene lactone concentration and composition during the season result in large variations in forage bitterness. 相似文献