全文获取类型
| 收费全文 | 2057篇 |
| 免费 | 19篇 |
专业分类
| 林业 | 60篇 |
| 农学 | 23篇 |
| 基础科学 | 2篇 |
| 186篇 | |
| 综合类 | 446篇 |
| 农作物 | 36篇 |
| 水产渔业 | 97篇 |
| 畜牧兽医 | 1125篇 |
| 园艺 | 42篇 |
| 植物保护 | 59篇 |
出版年
| 2024年 | 18篇 |
| 2023年 | 40篇 |
| 2022年 | 18篇 |
| 2021年 | 40篇 |
| 2020年 | 61篇 |
| 2019年 | 67篇 |
| 2018年 | 40篇 |
| 2017年 | 54篇 |
| 2016年 | 55篇 |
| 2015年 | 50篇 |
| 2014年 | 63篇 |
| 2013年 | 78篇 |
| 2012年 | 112篇 |
| 2011年 | 134篇 |
| 2010年 | 78篇 |
| 2009年 | 72篇 |
| 2008年 | 136篇 |
| 2007年 | 152篇 |
| 2006年 | 149篇 |
| 2005年 | 137篇 |
| 2004年 | 124篇 |
| 2003年 | 112篇 |
| 2002年 | 108篇 |
| 2001年 | 18篇 |
| 2000年 | 12篇 |
| 1999年 | 10篇 |
| 1998年 | 10篇 |
| 1997年 | 5篇 |
| 1996年 | 4篇 |
| 1994年 | 5篇 |
| 1993年 | 4篇 |
| 1992年 | 7篇 |
| 1991年 | 8篇 |
| 1990年 | 7篇 |
| 1989年 | 6篇 |
| 1987年 | 6篇 |
| 1986年 | 3篇 |
| 1985年 | 4篇 |
| 1983年 | 4篇 |
| 1980年 | 3篇 |
| 1979年 | 3篇 |
| 1977年 | 3篇 |
| 1975年 | 5篇 |
| 1974年 | 5篇 |
| 1970年 | 4篇 |
| 1969年 | 3篇 |
| 1967年 | 5篇 |
| 1945年 | 4篇 |
| 1940年 | 3篇 |
| 1937年 | 2篇 |
排序方式： 共有2076条查询结果，搜索用时 62 毫秒
191.
To assess the potential protective efficacy of a Salmonella enteritidis bacterin, an acetone-killed oil-emulsion vaccine was prepared from a phage type 13a S. enteritidis strain and administered subcutaneously to hens in two experiments. Hens were housed individually, and every other hen was vaccinated (at 23 weeks of age in one experiment and at 45 weeks in the other). A second (booster) bacterin injection was administered 6 weeks later in both experiments. Three weeks after the second vaccination, all hens were challenged with an oral dose of approximately 10(9) cells of a heterologous (phage type 14b) S. enteritidis strain. In both trials, S. enteritidis was isolated from fewer internal organs (spleens, ovaries, and oviducts) and pools of egg contents from vaccinated hens than from unvaccinated control hens. Vaccination did not, however, affect the percentage of hens that shed S. enteritidis in feces in either experiment. 相似文献
192.
193.
Infection of commercially reared white leghorn and white rock hens with adenovirus 127 was associated with decreases in total egg production, external egg quality, egg weight (P less than 0.01), and eggshell thickness (P less than 0.01). The egg-production and egg-quality disturbances were transient, and production returned to normal approximately 4 weeks postinfection. Infection of white leghorns with a hemagglutinating adenovirus isolated from Missouri ducks did not adversely affect egg production, external egg quality, or eggshell thickness, but it was associated with decreased egg weight (P less than 0.01). Prior infection with the duck adenovirus prevented the adverse egg-production effects of adenovirus 127 infection. Mean hemagglutination-inhibition antibody titers of chickens infected with adenovirus 127 or with duck adenovirus ranged from 1:588 to 1:10809, and mean titers of uninfected chickens did not exceed 1:2. 相似文献
194.
Danielle Butler Sarah Nemanic Jennifer J. Warnock 《Veterinary radiology & ultrasound》2018,59(1):43-53
Detection and accurate classification of traumatic tarsal fractures are important for identifying cases requiring surgical intervention. The aim of this prospective, experimental, methods comparison study was to directly compare the accuracy, sensitivity, and specificity of tarsal computed tomography (CT), ten‐view and two‐view digital radiographs for detecting traumatic fractures of the canine tarsus. The working hypothesis was that tarsal fractures would be detected with higher accuracy, sensitivity, and specificity using CT imaging compared to radiography, and a ten‐view would be superior to a two‐view radiographic study. Ten cadaver hind limbs of medium to large dogs received a CT scan and ten‐view radiographic study before and after induction of fractures with a hydraulic press. All bones included in the radiographic images were assessed for fractures by two observers and gross dissection was used as the gold standard. The two‐view radiographic study (dorsoplantar, lateromedial) was created from the ten‐view study and reviewed 2 years later. All limbs sustained fractures, the most common locations were the talus and calcaneus (n = 7). The sensitivity of CT was greater than ten‐view radiographic study (77% vs. 57%), while the specificity was similar (97% vs. 98%). The sensitivity and specificity of the ten‐view and two‐view radiograph studies were similar (57% vs. 55%; both 98%). Computed tomography images were reassessed postdissection to determine if failure to identify fractures resulted from observer error. Overall, CT was better than radiography for detecting fractures of the canine tarsus, however there was little improvement with ten‐view compared to two‐view radiographic studies. 相似文献
195.
196.
Computed tomographic myelography of a foal with discospondylitis and extradural spinal cord compression due to a vertebral abscess 
下载免费PDF全文
下载免费PDF全文 E. B. Garcia D. S. Biller L. Beard B. Bawa E. Nuth M. Goravanahally 《Equine Veterinary Education》2015,27(2):75-80
A one‐month‐old Quarter Horse colt presented with progressive gait abnormalities and weakness. The foal was ataxic at presentation. Radiography identified focal endplate irregularities and lysis at C6–7. Radiographic diagnosis was discospondylitis. Computed tomographic myelography was performed immediately following euthanasia and identified an extradural compressive spinal cord lesion corresponding to the site of discospondylitis. Post mortem examination findings included abscess formation at the C6–7 intervertebral space with osteomyelitis extending into the adjacent physes and subchondral bone of caudal C6 and cranial C7. The vertebral abscess extended into the ventral spinal canal at C6–7 and was identified as the cause of extradural spinal cord compression. Salmonella sp. was cultured and isolated from purulent exudate at the intervertebral space. Computed tomographic myelography has not been previously reported for assessment of discospondylitis in horses and was successful at accurately characterising spinal cord compression in addition to osteolytic changes associated with discospondylitis. 相似文献
197.
198.
Several avian influenza virus strains of hemagglutinin subtype 5 were assayed for sensitivity to the antiviral drug amantadine. Most strains exhibited little sensitivity to the drug as measured by plaque reduction. The A/Chicken/Scotland/59 (CS59), however, was highly sensitive, making it easily distinguishable from the other H5 strains. Drug sensitivity of the viruses was also assayed in chicken embryos. The in ovo patterns of amantadine sensitivity differed from those detected in cell culture. The CS59 isolate could not be distinguished from all the other strains on the basis of its response to amantadine in ovo. Although amantadine protected chickens inoculated with CS59 from morbidity and mortality, drug-resistant viruses were readily isolated from the infected birds. As found with other amantadine-resistant variants, the structure of the matrix gene was altered in the resistant isolates. These results demonstrate that amantadine resistance is widespread among avian influenza viruses of the H5 subtype, that drug sensitivity in cell culture does not necessarily reflect responses to amantadine in ovo and in vivo, and, as previously found, amantadine-resistant derivatives of H5 strains may be isolated from birds protected by the drug. 相似文献
199.
200.