全文获取类型
收费全文 | 474篇 |
免费 | 33篇 |
专业分类
林业 | 25篇 |
农学 | 6篇 |
基础科学 | 2篇 |
94篇 | |
综合类 | 65篇 |
农作物 | 18篇 |
水产渔业 | 14篇 |
畜牧兽医 | 251篇 |
园艺 | 13篇 |
植物保护 | 19篇 |
出版年
2023年 | 9篇 |
2022年 | 9篇 |
2021年 | 7篇 |
2020年 | 9篇 |
2019年 | 21篇 |
2017年 | 6篇 |
2016年 | 15篇 |
2015年 | 9篇 |
2014年 | 15篇 |
2013年 | 34篇 |
2012年 | 21篇 |
2011年 | 19篇 |
2010年 | 15篇 |
2009年 | 15篇 |
2008年 | 14篇 |
2007年 | 15篇 |
2006年 | 26篇 |
2005年 | 15篇 |
2004年 | 16篇 |
2003年 | 11篇 |
2002年 | 11篇 |
2001年 | 9篇 |
2000年 | 9篇 |
1999年 | 11篇 |
1998年 | 9篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1993年 | 4篇 |
1991年 | 7篇 |
1989年 | 4篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1974年 | 6篇 |
1973年 | 4篇 |
1972年 | 5篇 |
1971年 | 4篇 |
1970年 | 4篇 |
1969年 | 5篇 |
1967年 | 4篇 |
1948年 | 3篇 |
1947年 | 3篇 |
1945年 | 3篇 |
1942年 | 3篇 |
1939年 | 4篇 |
1938年 | 3篇 |
排序方式: 共有507条查询结果,搜索用时 78 毫秒
51.
McCann ME Rickes EL Hora DF Cunningham PK Zhang D Brideau C Black WC Hickey GJ 《American journal of veterinary research》2005,66(7):1278-1284
OBJECTIVE: To determine cyclooxygenase (COX)-2 selectivity, pharmacokinetic properties, and in vivo efficacy of firocoxib (ML-1,785,713) in cats. ANIMALS: 5 healthy male and 14 healthy female domestic shorthair cats. PROCEDURE: Selectivity of firocoxib for inhibiting COX-2 was determined by comparing the potency for inhibiting COX-1 with that of COX-2 in feline blood. Pharmacokinetic properties were determined after i.v. (2 mg/kg) and oral (3 mg/kg) administration in male cats. In vivo efficacy was evaluated in female cats with lipopolysaccharide (LPS)-induced pyrexia with administration of firocoxib 1 or 14 hours before LPS challenge. RESULTS: Blood concentrations resulting in 50% inhibition of COX-1 and COX-2 activity in vitro were 75 +/- 2 microM and 0.13 +/- 0.03 microM, respectively, and selectivity for inhibiting COX-2 relative to COX-1 was 58. Firocoxib had moderate to high oral bioavailability (54% to 70%), low plasma clearance (4.7 to 5.8 mL/min/kg), and an elimination half-life of 8.7 to 12.2 hours. Firocoxib at doses from 0.75 to 3 mg/kg was efficacious in attenuating fever when administered to cats 1 or 14 hours before LPS challenge. CONCLUSIONS AND CLINICAL RELEVANCE: Firocoxib is a potent COX-2 inhibitor and is the only selective COX-2 inhibitor described for use in cats to date. It is effective in attenuating febrile responses in cats when administered 14 hours before LPS challenge, suggesting it would be suitable for once-a-day dosing. Because selective COX-2 inhibitors have an improved therapeutic index relative to nonselective nonsteroidal anti-inflammatory drugs in humans, firocoxib has the potential to be a safe, effective anti-inflammatory agent for cats. 相似文献
52.
Thomas W. M. Cameron 《Canadian journal of veterinary research》1963,27(7):165-168
Animal diseases are of considerable importance to human welfare both as a cause of illness in man and as a factor in reducing the food potential of the world. Perhaps the most important factor affecting the less developed areas is malnutrition and, while explosive epidemics among animals are of great importance, the most important sources of losses are the chronic, sub-acute or sub-clinical infections, especially those caused by the parasitic worms. 相似文献
53.
McCann ME Andersen DR Zhang D Brideau C Black WC Hanson PD Hickey GJ 《American journal of veterinary research》2004,65(4):503-512
OBJECTIVE: To determine cyclooxygenase-2 (COX-2) selectivity, pharmacokinetic properties, and in vivo efficacy of ML-1,785,713 in dogs. ANIMALS: 21 healthy male and female mixed-breed dogs and 24 healthy male Beagles. PROCEDURE: Selectivity of ML-1,785,713 for inhibiting COX-2 was determined by comparing the potency for inhibiting cyclooxygenase-1 (COX-1) with that of COX-2 in canine blood. Pharmacokinetic properties were determined after i.v. (2 mg/kg) and oral (8 mg/kg) administration in female mixed-breed dogs. In vivo efficacy was evaluated in male mixed-breed dogs with urate crystal-induced synovitis. Prophylactic efficacy was evaluated by administering ML-1,785,713 two hours before induction of synovitis whereas therapeutic efficacy was determined by administering ML-1,785,713 one hour after induction of synovitis. RESULTS: Blood concentrations that resulted in 50% inhibition of COX-1 and COX-2 activity in vitro were 119.1 microM and 0.31 microM, respectively, and selectivity ratio for inhibiting COX-2 relative to COX-1 was 384. ML-1,785,713 had high oral bioavailability (101%), low systemic clearance (77 mL/min/kg), and an elimination half-life of 5.9 hours. ML-1,785,713 was efficacious when administered prophylactically and therapeutically to dogs with urate crystal-induced synovitis. CONCLUSIONS AND CLINICAL RELEVANCE: ML-1,785,713 is a novel, potent COX-2 inhibitor that is the most selective COX-2 inhibitor described for use in dogs to date. ML-1,785,713 has oral bioavailability and low systemic clearance that is comparable to other non-steroidal anti-inflammatory drugs. It is effective after prophylactic and therapeutic administration in attenuating lameness in dogs with urate crystal-induced synovitis. Drugs that specifically inhibit COX-2 and not COX-1 at therapeutic doses may have an improved tolerability profile, compared with nonselective non-steroidal anti-inflammatory drugs. 相似文献
54.
Seyfert M Mancini RA Hunt MC Tang J Faustman C Garcia M 《Journal of agricultural and food chemistry》2006,54(23):8919-8925
The objective was to characterize the beef psoas major (PM), longissimus lumborum (LL), superficial semimembranosus (SSM), deep semimembranosus (DSM), and semitendinosus (ST) muscles for differences in instrumental and visual color, metmyoglobin-reducing activity (MRA), total reducing activity (TRA), and cytochrome c oxidase activity. The LL and ST had the most color stability and MRA (p < 0.05), the DSM and PM had the least (p < 0.05), and values for the SSM were intermediate. Visual color (r = -0.66) and a and chroma (r = 0.68) were more correlated with MRA than with TRA (r < 0.14 for all measures). This research supports previous reports that color stability among muscles is variable and that MRA is more useful than TRA for explaining the role of reducing activity in muscle-color stability. 相似文献
55.
Cameron L Lalich N Bauer S Booker V Bogue HO Samuels S Steege AL 《Journal of agricultural safety and health》2006,12(2):139-153
Little is known about the magnitude of occupational health problems among migrant farm workers. A community-based cross-sectional survey was conducted in two migrant farm worker communities: Homestead, Florida, and Kankakee, Illinois. Camp Health Aides (CHAs) interviewed 425 workers about job tasks, personal protective equipment (PPE), field sanitation, work exposures, and selected health conditions. Limited provision of personal protective equipment was reported among those reporting early re-entry tasks: 35% in Kankakee and 42% in Homestead were provided gloves, and 22% in Homestead and 0% in Kankakee were provided protective clothing. About two-thirds were provided toilet facilities and water for hand-washing. Workers reported high prevalences of health conditions consistent with exposure to ergonomic hazards and pesticides. The prevalence of back pain in the past 12 months was 39% in Homestead and 24% in Kankakee. Among Homestead participants, 35% experienced eye symptoms, while 31% reported skin symptoms. These symptoms were less prevalent among Kankakee participants (16% for both eye and skin symptoms). Specific areas of concern included back pain associated with heavy lifting and ladder work; eye and skin irritation associated with fertilizer application tasks and with working in fields during or after spraying of chemicals, especially early re-entry of sprayed fields; and skin irritation associated with a lack of access to hand-washing facilities. In both Kankakee and Homestead, better adherence to safety standards is needed, as well as greater efforts to implement solutions that are available to help prevent work-related musculoskeletal problems. 相似文献
56.
57.
58.
Goutard FL Paul M Tavornpanich S Houisse I Chanachai K Thanapongtharm W Cameron A Stärk KD Roger F 《Preventive veterinary medicine》2012,105(3):223-234
For infectious diseases such as highly pathogenic avian influenza caused by the H5N1 virus (A/H5N1 HP), early warning system is essential. Evaluating the sensitivity of surveillance is a necessary step in ensuring an efficient and sustainable system. Stochastic scenario tree modeling was used here to assess the sensitivity of the A/H5N1 HP surveillance system in backyard and free-grazing duck farms in Thailand. The whole surveillance system for disease detection was modeled with all components and the sensitivity of each component and of the overall system was estimated. Scenarios were tested according to selection of high-risk areas, inclusion of components and sampling procedure, were tested. Nationwide passive surveillance (SSC1) and risk-based clinical X-ray (SSC2) showed a similar sensitivity level, with a median sensitivity ratio of 0.96 (95% CI 0.40-15.00). They both provide higher sensitivity than the X-ray laboratory component (SSC3). With the current surveillance design, the sensitivity of detection of the overall surveillance system when the three components are implemented, was equal to 100% for a farm level prevalence of 0.05% and 82% (95% CI 71-89%) for a level of infection of 3 farms. Findings from this study illustrate the usefulness of scenario-tree modeling to document freedom from diseases in developing countries. 相似文献
59.
Cameron AR 《Preventive veterinary medicine》2012,103(4):280-286
Risk factors associated with high or low long-term incidence of displaced abomasum (DA) or clinical ketosis were studied in 60 Swedish dairy herds, using multivariable logistic regression modelling. Forty high-incidence herds were included as cases and 20 low-incidence herds as controls. Incidence rates were calculated based on veterinary records of clinical diagnoses. During the 3-year period preceding the herd classification, herds with a high incidence had a disease incidence of DA or clinical ketosis above the 3rd quartile in a national database for disease recordings. Control herds had no cows with DA or clinical ketosis. All herds were visited during the housing period and herdsmen were interviewed about management routines, housing, feeding, milk yield, and herd health. Target groups were heifers in late gestation, dry cows, and cows in early lactation. Univariable logistic regression was used to screen for factors associated with being a high-incidence herd. A multivariable logistic regression model was built using stepwise regression. A higher maximum daily milk yield in multiparous cows and a large herd size (p = 0.054 and p = 0.066, respectively) tended to be associated with being a high-incidence herd. Not cleaning the heifer feeding platform daily increased the odds of having a high-incidence herd twelvefold (p < 0.01). Keeping cows in only one group in the dry period increased the odds of having a high incidence herd eightfold (p = 0.03). Herd size was confounded with housing system. Housing system was therefore added to the final logistic regression model. In conclusion, a large herd size, a high maximum daily milk yield, keeping dry cows in one group, and not cleaning the feeding platform daily appear to be important risk factors for a high incidence of DA or clinical ketosis in Swedish dairy herds. These results confirm the importance of housing, management and feeding in the prevention of metabolic disorders in dairy cows around parturition and in early lactation. 相似文献
60.