全文获取类型
收费全文 | 19006篇 |
免费 | 155篇 |
国内免费 | 1篇 |
专业分类
林业 | 3695篇 |
农学 | 1354篇 |
基础科学 | 141篇 |
3150篇 | |
综合类 | 1073篇 |
农作物 | 2296篇 |
水产渔业 | 1958篇 |
畜牧兽医 | 2343篇 |
园艺 | 1150篇 |
植物保护 | 2002篇 |
出版年
2023年 | 25篇 |
2021年 | 65篇 |
2020年 | 52篇 |
2019年 | 63篇 |
2018年 | 2796篇 |
2017年 | 2750篇 |
2016年 | 1228篇 |
2015年 | 140篇 |
2014年 | 101篇 |
2013年 | 119篇 |
2012年 | 963篇 |
2011年 | 2316篇 |
2010年 | 2185篇 |
2009年 | 1331篇 |
2008年 | 1457篇 |
2007年 | 1714篇 |
2006年 | 135篇 |
2005年 | 215篇 |
2004年 | 212篇 |
2003年 | 262篇 |
2002年 | 136篇 |
2001年 | 42篇 |
2000年 | 89篇 |
1999年 | 45篇 |
1998年 | 13篇 |
1997年 | 26篇 |
1996年 | 18篇 |
1995年 | 13篇 |
1994年 | 14篇 |
1993年 | 22篇 |
1992年 | 31篇 |
1991年 | 37篇 |
1990年 | 33篇 |
1989年 | 32篇 |
1988年 | 32篇 |
1987年 | 29篇 |
1986年 | 27篇 |
1985年 | 27篇 |
1984年 | 21篇 |
1983年 | 19篇 |
1979年 | 20篇 |
1977年 | 23篇 |
1974年 | 17篇 |
1973年 | 23篇 |
1972年 | 19篇 |
1971年 | 14篇 |
1970年 | 18篇 |
1969年 | 20篇 |
1968年 | 16篇 |
1966年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
82.
Comparison of three methods of temperature measurement in hypothermic, euthermic, and hyperthermic dogs 总被引:1,自引:0,他引:1
Greer RJ Cohn LA Dodam JR Wagner-Mann CC Mann FA 《Journal of the American Veterinary Medical Association》2007,230(12):1841-1848
OBJECTIVE: To assess the reliability and accuracy of a predictive rectal thermometer, an infrared auricular thermometer designed for veterinary use, and a subcutaneous temperature-sensing microchip for measurement of core body temperature over various temperature conditions in dogs. DESIGN: Prospective study. ANIMALS: 8 purpose-bred dogs. PROCEDURES: A minimum of 7 days prior to study commencement, a subcutaneous temperature-sensing microchip was implanted in 1 of 3 locations (interscapular, lateral aspect of shoulder, or sacral region) in each dog. For comparison with temperatures measured via rectal thermometer, infrared auricular thermometer, and microchip, core body temperature was measured via a thermistor-tipped pulmonary artery (TTPA) catheter. Hypothermia was induced during anesthesia at the time of TTPA catheter placement; on 3 occasions after placement of the catheter, hyperthermia was induced via administration of a low dose of endotoxin. Near-simultaneous duplicate temperature measurements were recorded from the TTPA catheter, the rectal thermometer, auricular thermometer, and subcutaneous microchips during hypothermia, euthermia, and hyperthermia. Reliability (variability) of temperature measurement for each device and agreement between each device measurement and core body temperature were assessed. RESULTS: Variability between duplicate near-simultaneous temperature measurements was greatest for the auricular thermometer and least for the TTPA catheter. Measurements obtained by use of the rectal thermometer were in closest agreement with core body temperature; for all other devices, temperature readings typically underestimated core body temperature. CONCLUSIONS AND CLINICAL RELEVANCE: Among the 3 methods of temperature measurement, rectal thermometry provided the most accurate estimation of core body temperature in dogs. 相似文献
83.
Young BC Strom AM Prittie JE Barton LJ 《Journal of the American Veterinary Medical Association》2007,231(1):74-78
CASE DESCRIPTION: 2 dogs were evaluated because of vomiting and lethargy (a Toy Poodle; dog 1) and acute respiratory distress, vomiting, and anorexia (a Chihuahua; dog 2). Dog 1 had been exposed to a commercial hydrocarbon waterproofing spray 24 hours before the development of clinical signs, and dog 2 was examined 18 hours after exposure to a waterproofing spray containing heptane, a highly flammable liquid hydrocarbon. CLINICAL FINDINGS: In both dogs, major gastrointestinal tract abnormalities were ruled out but respiratory status worsened. Thoracic radiography revealed a diffuse interstitial pulmonary pattern, and hypoxemia was detected. TREATMENT AND OUTCOME: Hospitalization for monitoring and care was required for both dogs. The dogs recovered with supportive care, which included administration of oxygen, fluids, and bronchodilators. Additionally, dog 1 received glucocorticoids via inhalation and supplemental enteral nutrition, whereas dog 2 was treated with an antimicrobial. CLINICAL RELEVANCE: The dogs of this report developed hydrocarbon pneumonitis following exposure to waterproofing sprays. Such sprays contain potentially toxic hydrocarbons. The severity of the adverse effects associated with exposure may have been amplified because the dogs were physically small and were exposed to a relatively large amount of aerosolized spray within small areas. Development of chemical pneumonitis in pet animals is best prevented by application of waterproofing sprays in well-ventilated or outdoor areas from which pets have been excluded. With prolonged hospitalization and considerable monitoring and care, affected dogs can recover from these exposures. 相似文献
84.
Ritter MJ Perry RL Olivier NB Kim SY Dejardin LM 《Journal of the American Animal Hospital Association》2007,43(2):93-98
A novel technique was developed to estimate the caudal medial tibial plateau landmark in the face of osteophytosis to improve accuracy in tibial plateau angle measurements. Using this technique, tibial plateau angles were evaluated in 31 normal dogs before and 8 months after right cranial cruciate ligament transection. There was no significant difference in mean tibial plateau angle before or after induction of osteophytosis. Additionally, it was determined that 90% of dogs had a difference of =2 degrees between right and left tibial plateau angles, which was considered symmetrical. 相似文献
85.
Schmitz JA Vogt RJ Rupp GP Brodersen BW Abel JM Wohlers AR Marx DB 《Journal of veterinary medical education》2007,34(3):340-349
Nebraska veterinary practitioners were surveyed to collect data about background characteristics and other factors related to veterinarians' decision to include or not include food animals in their practices and to practice in rural versus urban communities. Background characteristics that were significantly (p < or = 0.05) associated with choosing food-animal practice included growing up on a working farm or ranch; having parents who owned livestock; growing up in a town with a population of less than 10,000; majoring in animal science at university; being male; and having a primary interest, at the time of entering veterinary college, in food animal-exclusive or mixed-animal veterinary practice. The primary factor for choosing the community in which to practice was rural/urban lifestyle for rural veterinarians, while this factor was second for urban veterinarians. For all groups of veterinarians, the primary consideration in selecting their current practice was the species orientation of the practice. The primary reason for not choosing food-animal practice was better working conditions and lifestyle in companion-animal practice, followed by greater interest elsewhere. 相似文献
86.
87.
The purpose of this study was to determine the prevalence of positive allergen reactions in cats with small-airway disease (i.e. 'feline asthma', 'feline allergic bronchitis', 'feline bronchial disease'). Intradermal skin tests (IDT) and serum immunoglobulin E (IgE) tests were performed in 10 cats with idiopathic small-airway disease and in 10 normal cats without a history of respiratory disease. None of the cats had a history of skin disease or clinical signs of skin disease at the time of testing. Significantly more individual positive allergen reactions were found on serum IgE tests than on IDT in both groups of cats. Affected cats had significantly more individual positive allergen reactions on both tests than unaffected cats. Both IDT and serum IgE tests resulted in more individual positive allergen reactions to weeds, trees, grasses, and/or moulds in affected cats than in normal cats. Significantly more positive allergen reactions to house dust mites were found in affected compared to non-affected cats by IDT but not by serum IgE testing. One unexpected obstacle to inclusion of more affected cats in the study was the concurrent presence or history of suspect or known allergic skin disease. Concurrent allergic skin disease has not been reported in association with small-airway disease in cats. The increased prevalence of individual positive allergen reactions in affected cats may be due to increased immunological reactivity in these cats. Further studies are needed to answer this question and to determine what role, if any, aeroallergens have in the pathogenesis of this complex feline disease. 相似文献
88.
Batchelor DJ Noble PJ Cripps PJ Taylor RH McLean L Leibl MA German AJ 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2007,21(2):207-214
BACKGROUND: Knowledge of breed associations is valuable to clinicians and researchers investigating diseases with a genetic basis. HYPOTHESIS: Among symptomatic dogs tested for exocrine pancreatic insufficiency (EPI) by canine trypsin-like immunoreactivity (cTLI) assay, EPI is common in certain breeds and rare in others. Some breeds may be overrepresented or underrepresented in the population of dogs with EPI. Pathogenesis of EPI may be different among breeds. ANIMALS: Client-owned dogs with clinical signs, tested for EPI by radioimmunoassay of serum cTLI, were used. METHODS: In this retrospective study, results of 13,069 cTLI assays were reviewed. RESULTS: An association with EPI was found in Chows, Cavalier King Charles Spaniels (CKCS), Rough-Coated Collies (RCC), and German Shepherd Dogs (GSD) (all P < .001). Chows (median, 16 months) were younger at diagnosis than CKCS (median, 72 months, P < .001), but not significantly different from GSD (median, 36 months, P = .10) or RCC (median, 36 months, P = .16). GSD (P < .001) and RCC (P = .015) were younger at diagnosis than CKCS. Boxers (P < .001), Golden Retrievers (P < .001), Labrador Retrievers (P < .001), Rottweilers (P = .022), and Weimaraners (P = .002) were underrepresented in the population with EPI. CONCLUSIONS AND CLINICAL IMPLICATIONS: An association with EPI in Chows has not previously been reported. In breeds with early-onset EPI, immune-mediated mechanisms are possible or the disease may be congenital. When EPI manifests later, as in CKCS, pathogenesis is likely different (eg, secondary to chronic pancreatitis). Underrepresentation of certain breeds among dogs with EPI has not previously been recognized and may imply the existence of breed-specific mechanisms that protect pancreatic tissue from injury. 相似文献
89.
90.