全文获取类型
收费全文 | 135篇 |
免费 | 23篇 |
专业分类
林业 | 1篇 |
农学 | 3篇 |
基础科学 | 1篇 |
6篇 | |
综合类 | 24篇 |
农作物 | 1篇 |
水产渔业 | 46篇 |
畜牧兽医 | 74篇 |
植物保护 | 2篇 |
出版年
2021年 | 2篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 4篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 2篇 |
2013年 | 7篇 |
2012年 | 3篇 |
2011年 | 8篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 3篇 |
2007年 | 6篇 |
2006年 | 2篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2002年 | 2篇 |
2001年 | 2篇 |
1992年 | 5篇 |
1991年 | 8篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 7篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1980年 | 2篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1970年 | 1篇 |
1941年 | 1篇 |
1938年 | 1篇 |
1937年 | 1篇 |
1935年 | 1篇 |
1932年 | 1篇 |
1931年 | 3篇 |
1921年 | 1篇 |
1910年 | 1篇 |
1909年 | 1篇 |
1908年 | 2篇 |
1905年 | 1篇 |
1902年 | 1篇 |
1901年 | 1篇 |
1899年 | 1篇 |
1896年 | 1篇 |
1895年 | 2篇 |
排序方式: 共有158条查询结果,搜索用时 78 毫秒
91.
Eradication of the invasive Pseudorasbora parva results in increased growth and production of native fishes 总被引:1,自引:0,他引:1
Abstract – The topmouth gudgeon, Pseudorasbora parva , has been described as Europe's most invasive fish. To control their UK invasion, some lentic populations at risk of causing fluvial dispersal have been eradicated. The first of these operations was from a lake in north-west UK in March 2005 using rotenone application; prior to eradication, their mean density was estimated as 6.1 m−2 whereas since eradication, no P . parva have been recorded. Prior to rotenone application, the majority of native fishes were removed, held off-site and reintroduced following degradation of rotenone to safe levels. In the three growth seasons since their reintroduction and P . parva eradication, the abundance, somatic growth rate and production of roach Rutilus rutilus and common bream Abramis brama have increased significantly; production is now driven by a lower number of comparatively larger, faster growing individuals. These data suggest that the eradication of this P . parva population has been highly beneficial for the growth, recruitment and production of these native species. 相似文献
92.
93.
Michael Bynevelt FRANZCR Clare Rusbridge BVMS DECVN MRCVS Juliet Britton MRCP FRCR 《Veterinary radiology & ultrasound》2000,41(6):521-524
A nineteen month old Cavalier King Charles had clinical signs consistent with a cervical myelopathy. Radiologically there was abnormal angulation of the dens with cervical spinal cord compression and a Chiari type malformation of the atlanto-occipital region. The condition and method of investigation is discussed. 相似文献
94.
Roles of discharge and temperature in recruitment of a cold‐water fish,the European grayling Thymallus thymallus,near its southern range limit
下载免费PDF全文
![点击此处可从《Ecology of Freshwater Fish》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Tea Bašić J. Robert Britton Richard J. Cove Anton T. Ibbotson Stephen D. Gregory 《Ecology of Freshwater Fish》2018,27(4):940-951
Recruitment of salmonids is a result of density‐dependent factors, specifically egg production in the previous year, and density‐independent environmental processes driven by discharge and temperature. With the plethora of knowledge on major drivers of Atlantic salmon Salmo salar and brown trout Salmo trutta recruitment, there is a requirement to explore less known species, such as European grayling Thymallus thymallus, whose postemergence time coincides with period of increasing temperature and low discharge. This study assessed drivers of grayling recruitment in a southern English chalk stream, a system vulnerable to discharge and temperature alterations under future climate change predictions. The analyses explored age 0+ grayling survival in relation to conspecific and heterospecific densities and discharge‐ and temperature‐derived factors. The final mixed‐effects model revealed a positive relationship between age 0+ grayling survival and incubation temperature anomaly and age 0+ trout abundance. Similarly, postincubation temperature anomaly had a positive effect on 0+ grayling survival, but only up to a threshold temperature of 13.5°C, beyond which it had a negative effect. In contrast, increasing number of days with low discharge postincubation negatively influenced age 0+ grayling survival, with no evidence of an effect of elevated discharges following spawning. Our results emphasise the importance of maintaining natural discharge regimes in salmonid rivers by tackling multiple stressors operating at the catchment scale, including land and water use to mitigate for predicted climate driven changes. In addition, further research on recruitment drivers in less stable, rain‐fed systems, is required. 相似文献
95.
Stephens BB Gurney KR Tans PP Sweeney C Peters W Bruhwiler L Ciais P Ramonet M Bousquet P Nakazawa T Aoki S Machida T Inoue G Vinnichenko N Lloyd J Jordan A Heimann M Shibistova O Langenfelds RL Steele LP Francey RJ Denning AS 《Science (New York, N.Y.)》2007,316(5832):1732-1735
Measurements of midday vertical atmospheric CO2 distributions reveal annual-mean vertical CO2 gradients that are inconsistent with atmospheric models that estimate a large transfer of terrestrial carbon from tropical to northern latitudes. The three models that most closely reproduce the observed annual-mean vertical CO2 gradients estimate weaker northern uptake of -1.5 petagrams of carbon per year (Pg C year(-1)) and weaker tropical emission of +0.1 Pg C year(-1) compared with previous consensus estimates of -2.4 and +1.8 Pg C year(-1), respectively. This suggests that northern terrestrial uptake of industrial CO2 emissions plays a smaller role than previously thought and that, after subtracting land-use emissions, tropical ecosystems may currently be strong sinks for CO2. 相似文献
96.
97.
The interaction and stabling of horses at equine events may have a substantial impact on the spread of a zoonotic disease. This study aimed to investigate the spread of equine influenza (EI) at an equestrian event at the start of the Australian outbreak. Around one-third of the competing horses were stabled overnight at the event and, of these, 70% developed symptoms of EI within 7 days. The index case was never positively identified, but stabling position and disease onset provided clues to its potential identity. 相似文献
98.
Actinomycosis, presenting as chronic proliferative pyogranulomatous pleuritis associated with sulfur granules, was diagnosed in a mature male river otter (Lontra canadensis) captured near Victoria, British Columbia, Canada, in April 2010. The river otter died during sedation for clinical examination and was necropsied immediately. Bacteria of the genus Actinomyces are commensals of the mucous membranes in a wide range of animals and people that act as opportunistic pathogens. This is the first report of actinomycosis in a river otter. 相似文献
99.
Sandra Rideout-Hanzak David B. Wester Carlton M. Britton Heather Whitlaw 《Strength and Conditioning Journal》2011,64(1):47-55
In March 2006 the East Amarillo Complex (EAC) wildfires burned over 367 000 ha of short and mixed grass prairie of the southern High Plains, USA. We studied EAC wildfire effects on perennial grass mortality and peak standing crop on Deep Hardland and Mixedland Slopes ecological sites. Deep Hardlands were dominated by blue grama (Bouteloua gracilis H.B.K. [Griffiths]) and buffalograss (Buchloe dactyloides [Nutt.] Engelm.); common species on Mixedland Slopes were little bluestem (Schizachyrium scoparium [Michx.] Nash.) and sideoats grama (Bouteloua curtipendula [Michx.] Torr.) with scattered sand sagebrush (Artemisia filifolia Torr.) sometimes present. We hypothesized that perennial grass mortality would increase and standing crop would decrease following severe wildfire, and that these responses would be greater than documented prescribed fire effects. Frequency of perennial grass mortality was higher on both sites in burned areas than nonburned areas through three growing seasons following wildfire; however, standing crop was minimally affected. Results suggest that post-wildfire management to ameliorate wildfire effects is not necessary, and that wildfire effects in this area of the southern High Plains are similar to prescribed fire effects. 相似文献
100.