全文获取类型
收费全文 | 89篇 |
免费 | 6篇 |
专业分类
林业 | 12篇 |
农学 | 1篇 |
21篇 | |
综合类 | 7篇 |
农作物 | 5篇 |
水产渔业 | 6篇 |
畜牧兽医 | 40篇 |
园艺 | 2篇 |
植物保护 | 1篇 |
出版年
2021年 | 2篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 4篇 |
2015年 | 1篇 |
2014年 | 6篇 |
2013年 | 4篇 |
2012年 | 4篇 |
2011年 | 11篇 |
2010年 | 4篇 |
2009年 | 4篇 |
2008年 | 14篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
排序方式: 共有95条查询结果,搜索用时 46 毫秒
41.
se Helen Garseth Torfinn Moldal Siri Kristine Gsnes Monika Jankowska Hjortaas Vegard Pedersen Sollien Anne‐Gerd Gjevre 《Journal of fish diseases》2019,42(3):391-396
In 2017, a PCR‐based survey for Piscine orthoreovirus‐3 (PRV‐3) was conducted in wild anadromous and non‐anadromous salmonids in Norway. In seatrout (anadromous Salmo trutta L.), the virus was present in 16.6% of the fish and in 15 of 21 investigated rivers. Four of 221 (1.8%) Atlantic salmon (Salmo salar L.) from three of 15 rivers were also PCR‐positive, with Ct‐values indicating low amounts of viral RNA. All anadromous Arctic char (Salvelinus alpinus L.) were PCR‐negative. Neither non‐anadromous trout (brown trout) nor landlocked salmon were PRV‐3 positive. Altogether, these findings suggest that in Norway PRV‐3 is more prevalent in the marine environment. In contrast, PRV‐3 is present in areas with intensive inland farming in continental Europe. PRV‐3 genome sequences from Norwegian seatrout grouped together with sequences from rainbow trout (Oncorhynchus mykiss Walbaum) in Norway and Coho salmon (Oncorhynchus kisutch Walbaum) in Chile. At present, the origin of the virus remains unknown. Nevertheless, the study highlights the value of safeguarding native fish by upholding natural and artificial barriers that hinder introduction and spread, on a local or national scale, of alien fish species and their pathogens. Accordingly, further investigations of freshwater reservoirs and interactions with farmed salmonids are warranted. 相似文献
42.
Native starch granules of 11 selected cultivars (potato, waxy potato, sweet potato, normal maize, high‐amylose maize, waxy maize, wheat, normal barley, high‐amylose barley, waxy barley, and rice) were treated with a calcium chloride solution (4M) for surface gelatinization. The surface‐gelatinized starch granules were investigated using light microscopy and scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). In general, those starches with larger granule sizes required longer treatment time to complete the gelatinization. The salt solution treatment of starch was monitored by light microscopy and stopped when the outer layer of the granule was gelatinized. The surface gelatinized starch granules were studied using scanning electron microscopy. On the basis of the gelatinization pattern from calcium chloride treatments, the starches could be divided into three groups: 1) starches with evenly gelatinized granule surface, such as normal potato, waxy potato, sweet potato, maize, and high‐amylose maize; 2) starches with salt gelatinization concentrated on specific sites of the granule (i.e., equatorial groove), such as wheat, barley, and high‐amylose barley; and 3) starches that, after surface gelatinization, can no longer be separated to individual granules for SEM studies, such as waxy barley, waxy maize, and normal rice. The morphology of the surface gelatinized starch resembled that of enzyme‐hydrolyzed starch granules. 相似文献
43.
44.
Kristine Maki 《Biological conservation》2004,118(3):389-396
The extent to which invasive aquatic plants move via accidental inclusion in aquatic plant orders or sale of prohibited species is unknown. Forty orders were placed to 34 aquatic plant vendors across the US between May and September 2001 to determine the prevalence of movement into Minnesota via horticultural trade. Federal noxious weeds or Minnesota prohibited exotic species were acquired 92% of the time they were ordered and included Alternanthera sessilis, Butomus umbellata, Hydrocharis morsus-ranae, Potamogeton crispus, and Lythrum salicaria. Ninety three percent of orders received from aquatic plant vendors contained a plant or animal species not specifically requested; 10% of these purchases contained federal noxious weeds or Minnesota exotic species. Lemna minor was the most common incidental receipt found per taxa and per purchase, although Hydrilla verticillata, Lythrum salicaria, Salvinia molesta, and Potamogeton crispus (all prohibited taxa) were also found. Misidentified plants were found in 18% of the orders; unordered seeds in 43%. The sale and transport of prohibited aquatic plants likely presents the greatest risk associated with the aquatic plant trade. Other important factors include misidentification leading to the unintentional sale of invasive plants and the incidental inclusion of species during translocation. 相似文献
45.
Santacruz S Koch K Andersson R Aman P 《Journal of agricultural and food chemistry》2004,52(7):1985-1989
The starch accumulation-degradation process as well as the structure of leaf starch are not completely understood. To study this, starch was isolated from potato leaves collected in the early morning and late afternoon in July and August, representing different starch accumulation rates. The starch content of potato leaves varied between 2.9 and 12.9% (dry matter basis) over the night and day in the middle of July and between 0.6 and 1.5% in August. Scanning electron microscopy analyses of the four isolated starch samples showed that the granules had either an oval or a round shape and did not exceed 5 microm in size. Starch was extracted by successive washing steps with dimethyl sulfoxide and precipitated with ethanol. An elution profile on Sepharose CL-6B of debranched starch showed the presence of a material with a chain length distribution between that generally found for amylose and amylopectin. Amylopectin unit chains of low molecular size were present in a higher amount in the afternoon than in the morning samples. What remains at the end of the night is depleted in specific chain lengths, mainly between DP 15 and 24 and above DP 35, relative to the end of the day. 相似文献
46.
Guerrero TG Makara MA Katiofsky K Fluckiger MA Morgan JP Haessig M Montavon PM 《Veterinary surgery : VS》2011,40(1):27-33
Objective: To evaluate and compare healing, with and without the use of bone graft, of the gap created during tibial tuberosity advancement (TTA). Study Design: Prospective study and case series. Animals: Dogs treated with TTA (n=67). Methods: Prospective study: Mediolateral radiographic projections (6 weeks and 4 months) after TTA without use of bone graft (group I, n=14) were compared with radiographs of consecutive TTA in which the gap was filled with autologous cancellous bone graft (group II, n=14). Two scoring techniques (A, B) were used. Score A was used to grade the overall osteotomy healing (0=no healing, 4=healed osteotomy). Score B evaluated, independently of each other, healing in 3 sites: proximal to the cage (B1), between cage and plate (B2), and distal to the plate (B3). Case series: nongrafted TTA (4–25 weeks, n=39) were evaluated for healing (Score A). Data was analyzed using t‐tests and ANOVA. Significance was set at P≤.05. Results: Prospective study: Score A, B2, and B3 showed no difference in healing between groups at 6.8 weeks and 4.2 months. Score B1 revealed, in both rechecks, a significantly higher density in group II. Case series: Radiographs at 11.59±5.99 weeks scored 3.3 (2–4). No healing related complications were observed. Conclusion: The osteotomy gap created during TTA healed within expected time regardless of bone graft use. 相似文献
47.
48.
For more than two decades, researchers have argued that young children do not understand mental states such as beliefs. Part of the evidence for this claim comes from preschoolers' failure at verbal tasks that require the understanding that others may hold false beliefs. Here, we used a novel nonverbal task to examine 15-month-old infants' ability to predict an actor's behavior on the basis of her true or false belief about a toy's hiding place. Results were positive, supporting the view that, from a young age, children appeal to mental states--goals, perceptions, and beliefs--to explain the behavior of others. 相似文献
49.
Surface melt-induced acceleration of Greenland ice-sheet flow 总被引:2,自引:0,他引:2
Zwally HJ Abdalati W Herring T Larson K Saba J Steffen K 《Science (New York, N.Y.)》2002,297(5579):218-222
Ice flow at a location in the equilibrium zone of the west-central Greenland Ice Sheet accelerates above the midwinter average rate during periods of summer melting. The near coincidence of the ice acceleration with the duration of surface melting, followed by deceleration after the melting ceases, indicates that glacial sliding is enhanced by rapid migration of surface meltwater to the ice-bedrock interface. Interannual variations in the ice acceleration are correlated with variations in the intensity of the surface melting, with larger increases accompanying higher amounts of summer melting. The indicated coupling between surface melting and ice-sheet flow provides a mechanism for rapid, large-scale, dynamic responses of ice sheets to climate warming. 相似文献
50.
Brian J Knaus Richard Cronn Aaron Liston Kristine Pilgrim Michael K Schwartz 《BMC ecology》2011,11(1):1-14