首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   154篇
  免费   34篇
  国内免费   1篇
林业   5篇
农学   2篇
  13篇
综合类   18篇
农作物   2篇
水产渔业   2篇
畜牧兽医   137篇
园艺   1篇
植物保护   9篇
  2021年   2篇
  2019年   2篇
  2018年   4篇
  2017年   5篇
  2016年   5篇
  2015年   2篇
  2014年   8篇
  2013年   11篇
  2012年   8篇
  2011年   8篇
  2010年   4篇
  2009年   4篇
  2008年   8篇
  2006年   7篇
  2004年   4篇
  2003年   10篇
  2002年   4篇
  2001年   4篇
  2000年   9篇
  1998年   8篇
  1997年   2篇
  1996年   6篇
  1995年   3篇
  1994年   4篇
  1993年   7篇
  1992年   5篇
  1991年   5篇
  1990年   3篇
  1989年   6篇
  1988年   2篇
  1987年   2篇
  1986年   4篇
  1985年   1篇
  1982年   1篇
  1979年   1篇
  1978年   1篇
  1977年   1篇
  1974年   1篇
  1970年   1篇
  1967年   1篇
  1966年   1篇
  1964年   1篇
  1957年   1篇
  1941年   1篇
  1934年   1篇
  1926年   1篇
  1925年   1篇
  1922年   2篇
  1913年   1篇
  1912年   1篇
排序方式: 共有189条查询结果,搜索用时 15 毫秒
91.
CANINE HIP DYSPLASIA EVALUATION   总被引:1,自引:0,他引:1  
Victor T.  Rendano  Jr  VMD  MS  Gerald  Ryan  RT  AHT 《Veterinary radiology & ultrasound》1985,26(6):170-186
The ventrodorsal radiograph of the pelvis and femurs with the hind limbs extended, femurs parallel to each other, patellae superimposed over the distal femurs, and the pelvis symmetrical has become the standard method by which to evaluate animals for hip dysplasia. The following illustrated guide details the methods of positioning recommended by the American Veterinary Medical Association1 and used by the Orthopedic Foundation for Animals (OFA). Additionally, some commonly encountered positioning errors and methods of labeling radiographs are shown. The authors stress positioning requirements and aids they feel are necessary to produce an adequately positioned radiograph.  相似文献   
92.
This article presents an overview of the recent research into ovine and caprine mastitis. The common clinical presentations of mastitis in these species are reviewed, as are the important etiologic agents and their significance. The interpretation of somatic cell counts and surrogate tests, factors that affect somatic cell count levels, and association of somatic cell count levels with productivity are reviewed. Investigations into the treatment and prevention of mastitis and milking equipment function are discussed, and comments are made on the public health implications of extra label drug use and the consumption of unpasteurized milk.  相似文献   
93.
Obsessive-compulsive disorder (OCD) is characterized by repetitive thoughts and behaviors associated with underlying dysregulation of frontostriatal circuitry. Central to neurobiological models of OCD is the orbitofrontal cortex, a neural region that facilitates behavioral flexibility after negative feedback (reversal learning). We identified abnormally reduced activation of several cortical regions, including the lateral orbitofrontal cortex, during reversal learning in OCD patients and their clinically unaffected close relatives, supporting the existence of an underlying previously undiscovered endophenotype for this disorder.  相似文献   
94.
Measurements of the total burden and of the concentration versus altitude profiles of ozone have been made with a ground-based heterodyne radiometer at Pasadena, California. The measurements were made in the 9.5-micrometer wavelength region, where a strong ozone infrared absorption band exists. The radiometer measured solar absorption at selected wavelengths, with a spectral resolution of 0.001 reciprocal centimeter, equivalent to the half-width of an ozone absorption line at the 10-millibar altitude level. A carbon dioxide laser served as the local oscillator. This technique can be used to gather important data on both tropospheric and stratospheric ozone, which are not readily accessible with other remote-sensing techniques.  相似文献   
95.
96.
Whilst the topic of soil salinity has received a substantive research effort over the years, the accurate measurement and interpretation of salinity tolerance data remain problematic. The tolerance of four perennial grass species (non-halophytes) to sodium chloride (NaCl) dominated salinity was determined in a free-flowing sand culture system. Although the salinity tolerance of non-halophytes is often represented by the threshold salinity model (bent-stick model), none of the species in the current study displayed any observable salinity threshold. Further, the observed yield decrease was not linear as suggested by the model. On re-examination of earlier datasets, we conclude that the threshold salinity model does not adequately describe the physiological processes limiting growth of non-halophytes in saline soils. Therefore, the use of the threshold salinity model is not recommended for non-halophytes, but rather, a model which more accurately reflects the physiological response observed in these saline soils, such as an exponential regression curve.  相似文献   
97.
98.
Tuberculosis (TB) is a significant animal health problem in many parts of the world, and reservoirs of infection in wild animals complicate disease control efforts in farmed livestock, particularly cattle. Badgers (Meles meles) are a significant wildlife reservoir of Mycobacterium bovis infection for cattle in the United Kingdom (UK) and Republic of Ireland (ROI). Vaccination of badgers using an M. bovis strain bacille Calmette-Guérin (BCG) vaccine could potentially be an option in the national TB eradication strategy. Wildlife vaccination has been used successfully for other diseases in wildlife species, and may have a role to play in reducing M. bovis transmission at the wildlife-livestock interface. Research to date has provided evidence that BCG is protective in badgers, and a parenteral badger BCG vaccine has been licensed in the UK. Further research is required to develop effective strategies for vaccine deployment and to determine the effect of badger vaccination on cattle TB incidence.  相似文献   
99.
100.
The purpose of this study was to examine the prevalence and patterns of antimicrobial resistance (AMR) in enteric bacteria obtained from Ontario sheep flocks, and associations between antimicrobial use (AMU) and AMR. Forty-nine sheep producers participated for a 1-year interval between 2006 and 2008. Two-hundred and eighty-three pooled fecal samples were collected from the flocks during initial and final visits. Up to 3 isolates of Salmonella spp. and generic E. coli per pooled fecal sample were tested for susceptibility to 15 antimicrobials. Resistance was infrequent among Salmonella (0%, n = 7 isolates) and low among E. coli (13.1%; n = 849) isolates. A small number of isolates were resistant to antimicrobials classified as being of very high importance to human health. Tetracycline resistance was most frequently observed (12.0%). Logistic regression was used to model potential AMU (qualitative and quantitative) risk factors for tetracycline resistance in generic E. coli from final visits. Qualitative analysis indicated that the use of injectable sulfonamides [including trimethoprim-sulfonamide combinations (TMS)] and tetracycline in the feed and water were significantly associated with tetracycline resistance (OR = 2.6, P = 0.01; and OR = 4.8, P ≤ 0.01, respectively). Quantitative analysis also indicated that TMS exposure rate was significantly associated with tetracycline resistance, which varied depending on the exposure rate. The exposure rate of tetracycline in the feed and water was only significant after the removal of one influential flock, warranting further research examining flocks with higher tetracycline exposure rates. Although the prevalence of AMR in participating flocks was relatively low, risk factors for resistance were identified.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号