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   447篇
  免费   63篇
林业   7篇
基础科学   1篇
  14篇
综合类   26篇
农作物   12篇
水产渔业   19篇
畜牧兽医   413篇
园艺   1篇
植物保护   17篇
  2023年   8篇
  2022年   5篇
  2020年   31篇
  2018年   22篇
  2017年   13篇
  2016年   14篇
  2015年   17篇
  2014年   27篇
  2013年   33篇
  2012年   20篇
  2011年   26篇
  2010年   27篇
  2009年   40篇
  2008年   17篇
  2007年   14篇
  2006年   18篇
  2005年   10篇
  2004年   19篇
  2003年   16篇
  2002年   15篇
  2001年   16篇
  2000年   8篇
  1999年   9篇
  1998年   4篇
  1997年   3篇
  1996年   6篇
  1995年   5篇
  1994年   5篇
  1993年   6篇
  1992年   5篇
  1991年   3篇
  1990年   6篇
  1989年   3篇
  1988年   4篇
  1987年   4篇
  1986年   3篇
  1984年   5篇
  1982年   1篇
  1981年   2篇
  1978年   1篇
  1976年   1篇
  1975年   1篇
  1972年   1篇
  1966年   2篇
  1965年   1篇
  1961年   1篇
  1960年   2篇
  1959年   1篇
  1958年   4篇
  1957年   2篇
排序方式: 共有510条查询结果,搜索用时 218 毫秒
81.
82.
83.
Objective— Force platform gait analysis is a recognized clinical evaluation tool that captures and documents the in vivo pathomechanics of osteoarthritis (OA). In a clinical trial designed to evaluate the impact of 2 specific diets, an increase in body weight (BW) was observed in lame client-owned dogs. Covariance analysis was used to evaluate the interference of BW changes toward the evolution of peak vertical force (PVF) values. These secondary findings are reported in this study.
Study Design— Prospective study.
Animals— Lame dogs (n=26).
Methods— Dogs with radiographic evidence of OA and low PVF values were fed with 2 specific diets for 30 and 60 days. PVF and BW were recorded at baseline, day 30 (D30), and D90.
Results— Mean (±SD) PVF values (%BW) did not differ significantly over time (D0: 63.9±17.2; D30: 65.5±17.4; and D90: 66.5±20.1). In contrast, BW (kg) was significantly higher at D90 (41.3±7.9) when compared with D30 (39.9±8.4) and D0 (40.0±8.7). Upon covariance analyses, BW changes interfere significantly with PVF values already normalized in %BW ( P =.013). Values of PVF adjusted using BW as a covariate were then 63.4±17.1 (D0), 65.0±17.3 (D30), and 67.6±20.5 (D90), whereas D90 was significantly higher than D0.
Conclusion— These findings highlighted the interference of changes in BW toward locomotor function of OA dogs when using PVF values normalized in %BW. Exacerbation of lameness when a gain in BW occurred was also sustained, raising a possible bias in clinical study outcomes.
Clinical Relevance— A BW increase in dogs with OA could exacerbate a preexisting lameness and induce a bias in clinical trials.  相似文献   
84.
Objectives: To report the repair of tibial diaphyseal fractures in 2 calves using a circular external skeletal fixator (CEF). Study Design: Clinical report. Animals: Crossbred calves (n=2; age: 6 months; weight: 55 and 60 kg). Methods: Mid‐diaphyseal tibial fractures were repaired by the use of a 4‐ring CEF (made of aluminum rings with 2 mm K‐wires) alone in 1 calf and in combination with hemicerclage wiring in 1 calf. Results: Both calves had good weight bearing with moderate lameness postoperatively. Fracture healing occurred by day 60 in 1 calf and by day 30 in calf 2. The CEF was well maintained and tolerated by both calves through fracture healing. Joint mobility and limb usage improved gradually after CEF removal. Conclusions: CEF provided a stable fixation of tibial fractures and healing within 60 days and functional recovery within 90 days. Clinical Relevance: CEF can be safely and successfully used for the management of selected tibial fractures in calves.  相似文献   
85.
Four different types of bedding materials (wheat straw, wood shavings, hemp shives, flax shives) and two roughages (hay, haylage) were treated using an air-driven particle separation technology. The airborne particle and mold generation of both treated and untreated samples were then analyzed under standardized laboratory conditions. In addition, samples of all the treated materials were stored for 8 weeks either in a pressed or incoherent form and then analyzed again for their ability to generate airborne particles. The airborne particle concentrations were detected online with the gravimetrically measuring analyzer tapered element oscillating microbalance (TEOM) 1400a that was equipped successively with different inlets to measure the particle fractions PM20, PM10, PM2.5, and PM1.0 (PM = Particulate matter). The particle separation resulted in a reduction in the airborne particle (PM20) generation in all materials: hay 49.16 to 22.79 mg/m3 (53.6%), haylage 28.57 to 25.04 mg/m3 (12.3%), wood shavings 141.68 to 15.04 mg/m3 (89.4%), wheat straw 143.08 to 22.97 mg/m3 (83.9%), flax 135.11 to 53.31 mg/m3 (60.5%), and hemp 63.67 to 17.64 mg/m3 (72.3%). The 8-week storage of the treated materials as compressed materials led to a renewed significant increase in the airborne particle (PM10) concentration in the haylage (+29.9%), wheat straw (+104.0%), wood shavings (+40.4%), and hemp shives (+30.7%). Storage of the incoherent materials caused a significant increase in these particles only in the wheat straw (+44.2%). The separation treatment reduced the mold production by 92.4% in the wood shavings, 88.0% in the wheat straw, and 85.8% in the hay.  相似文献   
86.
A 3-week-old Friesian colt with a history of respiratory distress since birth was presented to our facility. Results after an endoscopy showed obstruction of the right nasal passage to the nasopharynx. Computed tomography was performed to further characterize this unilateral blockage. The images demonstrated a complete membranous obstruction of the ventral meatus, along with deviation of the vomer bone toward the left side of the nasal cavity. The diagnosis of unilateral choanal atresia was confirmed. This report is the first to describe computed tomographic features of choanal atresia in a foal.  相似文献   
87.
Root and stem rot (RSR) is a very detrimental disease of vanilla worldwide. Fusarium oxysporum is frequently associated with the disease but other Fusarium species are also reported. In this international study, 52 vanilla plots were surveyed in three of the most important vanilla producing countries (Madagascar, Reunion Island and French Polynesia) in order to determine the aetiology of RSR disease. Subsets from the 377 single‐spored Fusarium isolates recovered from rotten roots and stems in the surveys were characterized by molecular genotyping (EF1α and IGS gene sequences) and pathogenicity assays on Vanilla planifolia and V. ×tahitensis, the two commercially grown vanilla species. Fusarium oxysporum was shown to be the principal species responsible for the disease, representing 79% of the isolates recovered from the RSR tissues, 40% of which induced severe symptoms on inoculated plantlets. Fusarium oxysporum isolates were highly polyphyletic regardless of geographic origin or pathogenicity. Fusarium solani, found in 15% of the samples and inducing only mild symptoms on plantlets, was considered a secondary pathogen of vanilla. Three additional Fusarium species were occasionally isolated in the study (F. proliferatum, F. concentricum and F. mangiferae) but were nonpathogenic. Histopathological preparations observed in wide field and multiphoton microscopy showed that F. oxysporum penetrated the root hair region of roots, then invaded the cortical cells where it induced necrosis in both V. planifolia and V. ×tahitensis. The hyphae never invaded the root vascular system up to 9 days post‐inoculation. As a whole, the data demonstrated that RSR of vanilla is present worldwide and that its causal agent should be named F. oxysporum f. sp. radicis‐vanillae.  相似文献   
88.
In Germany, most competition horses are housed in single stalls and free exercise is not permitted in many cases. The reason for not allowing free exercise is mostly the risk of injury. Additionally, opinions exist that the horses’ demand for exercise is fulfilled by training and that the horses’ willingness to perform is negatively influenced by free exercise. In the present study, three turnout practices were investigated with regard to their effect on the behavior of four horses: daily training without free exercise (no turnout), 2-hour turnout (for free exercise) before training, and 2-hour turnout after training. The aim of this study was to determine any differences in the horses’ behavior between the three treatments. The horses’ behavior in the stable was observed through video recordings. The behavior during turnout was observed directly and during training was evaluated by the riders with the aid of a questionnaire. Additionally, the distance covered during turnout was measured by Global Positioning System devices. The behavior within the stall was more restless in the treatment without turnout—which became apparent in significantly more frequent changes between behaviors as compared with the treatments with turnout. The results of Global Positioning System measurement during turnout showed a significantly shorter distance covered when horses were trained before they were turned out compared with turnout before training. If the horses were turned out after training, they also showed less trotting and cantering and more dozing. The horses’ willingness to perform was not significantly different between the three treatments.  相似文献   
89.
90.
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