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   123篇
  免费   8篇
林业   16篇
农学   1篇
  12篇
综合类   11篇
农作物   6篇
水产渔业   38篇
畜牧兽医   37篇
园艺   2篇
植物保护   8篇
  2023年   4篇
  2021年   1篇
  2020年   2篇
  2019年   3篇
  2018年   6篇
  2017年   2篇
  2016年   4篇
  2015年   7篇
  2014年   6篇
  2013年   10篇
  2012年   9篇
  2011年   10篇
  2010年   4篇
  2009年   4篇
  2008年   7篇
  2007年   3篇
  2006年   6篇
  2005年   4篇
  2004年   8篇
  2003年   7篇
  2002年   10篇
  2001年   3篇
  2000年   2篇
  1999年   1篇
  1998年   2篇
  1996年   1篇
  1995年   2篇
  1987年   1篇
  1986年   1篇
  1984年   1篇
排序方式: 共有131条查询结果,搜索用时 93 毫秒
111.
A retrospective study was performed of 100 dogs with persistent urinary tract infections (UTIs) or reinfections presenting to the North Carolina State University (Raleigh, NC) Veterinary Teaching Hospital between 1989 and 1999. Criteria for selection included > or = 2 positive urine cultures within a 6-month period. Signalment, presence of predisposing disorders, urinalysis and urine culture results, and treatment strategies were extracted from the medical records. Dogs were a median age of 7 years when the UTI was 1st diagnosed. Dogs younger than 3 and older than 10 years were at increased and decreased risks, respectively, for reinfections or persistent UTIs. Spayed females were more common in the UTI population. More than half of the dogs were asymptomatic for a UTI at 1st presentation. Urine sediment examinations identified hematuria, pyuria, and bacteriuria in 47, 72, and 85% of the samples, respectively. The most commonly isolated organisms were Escherichia coli and Streptococcus/Enterococcus spp.; multiple isolates also were common. Of the isolates, 29.5% were resistant to achievable serum concentrations of all antibiotics commonly prescribed for PO administration. Dogs with abnormal micturition were more likely to have infections by organisms resistant to commonly prescribed antibiotics. Potentially predisposing disorders were identified in 71 dogs. A correction of these disorders was accomplished in 35% of these 71 dogs. Dogs given standard antibiotic therapy without addressing predisposing disorders experienced poor control of their UTIs; 74.5% of these dogs had an apparent disease-free interval (ADFI) of < 8 weeks. By comparison, dogs in which predisposing disorders were corrected or those that were treated with low-dose, long-term antibiotic regimens subjectively had better control.  相似文献   
112.
OBJECTIVE: To evaluate the use of the anesthetic combination tiletamine, zolazepam, ketamine, and xylazine (TKX) for anesthesia of feral cats at large-scale neutering clinics. DESIGN: Original study. ANIMALS: 7,502 feral cats. PROCEDURE: Cats were trapped by their caretakers for a feral cat neutering program from July 1996 to August 2000. The anesthetic combination TKX was injected IM into cats while they remained in their traps. Each milliliter of TKX contained 50 mg of tiletamine, 50 mg of zolazepam, 80 mg of ketamine, and 20 mg of xylazine. Females were spayed by veterinarians, whereas males were castrated by veterinarians or veterinary students. Yohimbine (0.5 mg, IV) was administered at the end of the procedure. Logs were kept of the individual drug doses, signalment of the cats, and any complications encountered. These data were analyzed retrospectively (1996 to 1999) and prospectively (2000). RESULTS: Of the 5,766 cats for which dosing records were complete, 4,584 (79.5%) received a single dose of TKX. The mean initial dose of TKX was 0.24 +/- 0.04 ml/cat, and the total mean dose of TKX was 0.27 +/- 0.09 ml. Overall mortality rate was 0.35% (26/7,502) cats, and the death rate attributable solely to potential anesthetic deaths was 0.23% (17/7,502) cats. CONCLUSIONS AND CLINICAL RELEVANCE: The use of TKX for large-scale feral cat neutering clinics has several benefits. The TKX combination is inexpensive, provides predictable results, can be administered quickly and easily in a small volume, and is associated with a low mortality rate in feral cats.  相似文献   
113.
Models for predicting microfibril angle variation in Scots pine   总被引:1,自引:0,他引:1  

Context

Microfibril angle (MFA) is one of the key determinants of solid timber performance due to its strong influence on the stiffness, strength, shrinkage properties and dimensional stability of wood.

Aims

The aim of this study was to develop a model for predicting MFA variation in plantation-grown Scots pine (Pinus sylvestris L). A specific objective was to quantify the additional influence of growth rate on the radial variation in MFA.

Methods

Twenty-three trees were sampled from four mature Scots pine stands in Scotland, UK. Pith-to-bark MFA profiles were obtained on 69 radial samples using scanning X-ray diffractometry. A nonlinear mixed-effects model based on a modified Michaelis–Menten equation was developed using cambial age and annual ring width as explanatory variables.

Results

The largest source of variation in MFA (>90 %) was within trees, while between-tree variation represented just 7 % of the total. Microfibril angle decreased rapidly near the pith before reaching stable values in later annual rings. The effect of ring width on MFA was greater at higher cambial ages.

Conclusion

A large proportion of the variation in MFA was explained by the fixed effects of cambial age and annual ring width. The final model is intended for integration into growth, yield and wood quality simulation systems.  相似文献   
114.
Tropical Animal Health and Production - Commercial small-scale chicken farms managed as all-in-all-out but operating with low standards of hygiene/biosecurity are increasingly common in Vietnam....  相似文献   
115.
A number of raw materials were tested to obtain the in vivo apparent digestibility coefficients of protein, lipid and gross energy for gilthead bream. Sparus auratus L., under controlled conditions. In the case of protein digestibility assessment, a standard in vitro method was also included for comparison. Protein digestibility coefficients were generally high, with values between 60% and 96% being observed for most of the materials studied. However, some exceptions were apparent in materials of both animal and plant origin. Lipid digestibilities also ranged between 50% and 90%. Values for energy digestibilities indicated a much greater variation, from 6% to 80%. These observations are discussed in relation to the nature and source of ingredients and to the type of processing technology employed.  相似文献   
116.
Two growth trials were conducted to evaluate the nutritional quality of several soybean products as constituents in diets for the gilthead sea bream, Sparus aurata (L.). In a preliminary experiment, the fish were fed six diets containing different levels of solvent extracted soybean meal as a replacement for white fishmeal at four substitution levels: 10, 20, 30 and 40% of the fishmeal protein component. The diets supported less growth as the inclusion of soybean meal increased. However, significant reductions in growth were apparent at the 30% substitution level. All growth parameters followed the same trend. In the second experiment, six diets with 35% of the total protein contributed from differently processed soybean meals were tested. The products included three industrial full-fat meals heat processed for different periods, a solvent extracted meal and a soya protein concentrate. Protein digestibility coefficients were measured for all the experimental diets. All growth parameters of the fish fed the underheated full-fat meal, solvent extracted meal and soya concentrate were significantly lower than the control group. Protein digestibility coefficients were similar with no statistical differences (P < 0.05).  相似文献   
117.
118.
Five diets having the same proximate composition but containingdifferent types of supplemental oils, singly or in combination, were used forgrowing sea bass from 95 g to about 200 g in smallseacages. The oils tested were olive oil, soybean oil and fish oil. The dietsformulated contained EPA and DHA levels ranging from 0.88 to 1.35% of the diet.Growth parameters and fish body composition were not significantly affected bythe type of oil used. The same was generally apparent for liver andhematological characteristics. The content of phospholipids in EPA and DHA washighest in the livers of fish fed diets supplemented with fish oil. A positivecorrelation was found between dietary and liver n-6 PUFA. Histological sectionsindicated extended pathological symptoms (intensive liver degeneration andhemorrhages, changes in the gill structure) in the fish receiving dietssupplemented only with plant oils. These symptoms existed but to a smallerfrequency and degree in livers of fish fed diets supplemented with plant andfish oil, while were not apparent in those fed the fish oil diet.  相似文献   
119.
120.
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