全文获取类型
| 收费全文 | 307篇 |
| 免费 | 33篇 |
| 国内免费 | 2篇 |
专业分类
| 林业 | 7篇 |
| 农学 | 8篇 |
| 基础科学 | 1篇 |
| 19篇 | |
| 综合类 | 23篇 |
| 农作物 | 12篇 |
| 水产渔业 | 17篇 |
| 畜牧兽医 | 241篇 |
| 园艺 | 3篇 |
| 植物保护 | 11篇 |
出版年
| 2023年 | 5篇 |
| 2022年 | 3篇 |
| 2021年 | 14篇 |
| 2020年 | 11篇 |
| 2019年 | 6篇 |
| 2018年 | 16篇 |
| 2017年 | 15篇 |
| 2016年 | 16篇 |
| 2015年 | 2篇 |
| 2014年 | 21篇 |
| 2013年 | 25篇 |
| 2012年 | 15篇 |
| 2011年 | 20篇 |
| 2010年 | 18篇 |
| 2009年 | 16篇 |
| 2008年 | 7篇 |
| 2007年 | 13篇 |
| 2006年 | 12篇 |
| 2005年 | 6篇 |
| 2004年 | 8篇 |
| 2003年 | 5篇 |
| 2002年 | 5篇 |
| 2001年 | 7篇 |
| 2000年 | 4篇 |
| 1999年 | 3篇 |
| 1998年 | 15篇 |
| 1997年 | 10篇 |
| 1996年 | 11篇 |
| 1995年 | 10篇 |
| 1994年 | 2篇 |
| 1993年 | 3篇 |
| 1992年 | 5篇 |
| 1991年 | 2篇 |
| 1990年 | 3篇 |
| 1989年 | 3篇 |
| 1988年 | 3篇 |
| 1970年 | 1篇 |
| 1967年 | 1篇 |
排序方式： 共有342条查询结果，搜索用时 15 毫秒
21.
A 2-year-old Thoroughbred gelding was evaluated for a grade 3 out of 5 unilateral hind limb lameness. Flexion of the right hock and stifle joints (spavin test) exacerbated the lameness. Response to intra-articular and perineural anaesthesia isolated the source of lameness to the tarsocrural area, despite an absence of tarsocrural joint effusion. Routine radiographic examination of the hock did not reveal any significant abnormalities. Skeletal nuclear scintigraphic evaluation revealed a focal region of increased bone activity in the proximal medial trochlear ridge of the talus. Flexed lateromedial radiographic views identified three discrete semicircular lytic lesions at the proximal articular margin of the medial trochlear ridge of the talus. Conservative management of the lesions was associated with a successful return to racing. The location and appearance of the osteochondral lesions of this report have not been previously reported and may be a manifestation of developmental orthopaedic disease and abnormal endochondral ossification. Nuclear scintigraphy and flexed lateromedial radiographic views facilitated identification of the lesions. This radiographic view is recommended when lameness is isolated to the tarsocrural joint and standard radio-graphic projections fail to identify a cause. 相似文献
22.
The silica-supported transition metal hydrides (=Si-O-Si=)(=Si-O-)2Ta-H and (=Si-O-)xM-H (M, chromium or tungsten) catalyze the metathesis reaction of linear or branched alkanes into the next higher and lower alkanes at moderate temperature (25degrees to 200degreesC). With (=Si-O-Si=)(=Si-O-)2Ta-H, ethane was transformed at room temperature into an equimolar mixture of propane and methane. Higher and lower homologs were obtained from propane, butane, and pentane as well as from branched alkanes such as isobutane and isopentane. The mechanism of the step leading to carbon-carbon bond cleavage and formation likely involves a four-centered transition state between a tantalum-alkyl intermediate and a carbon-carbon final sigma-bond of a second molecule of alkane. 相似文献
23.
Spatial Variability of Turbulent Mixing in the Abyssal Ocean 总被引：3，自引：0，他引：3
Ocean microstructure data show that turbulent mixing in the deep Brazil Basin of the South Atlantic Ocean is weak at all depths above smooth abyssal plains and the South American Continental Rise. The diapycnal diffusivity there was estimated to be less than or approximately equal to 0.1 x 10(-4) meters squared per second. In contrast, mixing rates are large throughout the water column above the rough Mid-Atlantic Ridge, and the diffusivity deduced for the bottom-most 150 meters exceeds 5 x 10(-4) meters squared per second. Such patterns in vertical mixing imply that abyssal circulations have complex spatial structures that are linked to the underlying bathymetry. 相似文献
24.
A Brucella ovis surface protein antigen (P-II), obtained by gel filtration with Sepharose 4B of a hot saline extract was characterized. The analysis of P-II over gradient sodium dodecylsulfate electrophoresis yielded an 18.5 and a 20 kDa band. In a radioimmunoprecipitation assay using P-II labeled with 125I, the antigen reacted specifically only with sera from rams experimentally infected with a naturally occurring rough strain of B. ovis and did not react with sera from rams experimentally infected with other smooth Brucella strains (B. abortus and B. melitensis). 相似文献
25.
de Francischini Carvalho AC Pacheco MR Baraldi Artoni SM Mateus O 《Anatomia, histologia, embryologia》2006,35(5):284-286
This inedited morphometric study has been developed from healthy canine spinal cord neuron cytoplasm and nucleus, and white matter axonal myelin sheath, from cervical, thoracic and lumbar regions. For the morphometric study, the parameters were area, perimeter, maximum and minimum diameters and roundness for neurons and myelin thickness for axon. For each parameter, 300 neurons were analysed. The results revealed that lumbar neurons had the highest mean values for the analysed parameters, indicating the presence of large neurons in this region, with large axons as a result of myelin thickness, which is proportional to axon calibre. We conclude that these morphometric results can contribute for the establishment of normal patterns, for canine spinal cord cervical, thoracic and lumbar segments. 相似文献
26.
27.
28.
29.
30.