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71.
OBJECTIVES: To define the release of nitric oxide (NO), prostaglandin E2 (PGE2), and the neutral metalloproteinases (NMPs) in horses with subchondral cystic lesions (SCL) and to study bone resorption triggered by conditioned media of fibrous tissue of SCL in vitro. STUDY DESIGN: Equine explant cultures of fibrous tissue of SCL, and synovial membrane and articular cartilage of normal horses and horses affected with moderate and severe osteoarthritis were performed. NO, PGE2, and NMP concentrations of media samples were measured, and osteoclast formation and activation was studied in vitro. ANIMALS: Experiment 1: 32 horses with SCL (n = 8), normal joints (7), and joints with moderate (7) and severe (10) osteoarthritis (OA). Experiment 2: 22 horses with SCL (n = 3), normal joints (7), and chip fractures (12). Experiment 3: Conditioned media of fibrous tissue from 3 horses with SCL of the medial femoral condyle (n = 1), distal metacarpal bone (1), and tarsal bone (1). METHODS: Determinations of local mediator concentrations were made with the Griess assay for NO and an enzyme immunoassay kit for PGE2 concentrations in biological fluids. Enzyme activities were assessed with radiolabeled substrates indicating collagenolytic, gelatinolytic, and caseinolytic activities. The resorption pit assay was used to assess osteoclast recruitment and activity. RESULTS: Fibrous tissue of SCL produced NO, PGE2, and NMPs. Of all the variables measured, PGE2 concentrations were the highest in cystic tissue of SCL compared with synovial membrane and articular cartilage from normal joints and joints with chip fractures, indicating that this mediator may play an important role in pathological bone resorption associated with SCL. These findings were supported by the observation that conditioned media of SCL tissue were capable of recruiting osteoclasts and increasing their activity. CONCLUSION: Fibrous tissue of SCL released NO, PGE2, and NMPs into the culture media. It is suspected that intralesional fibrous tissue may play an active role in the pathological process of bone resorption occurring in SCL in horses and may be partly responsible for the maintenance, slow healing rate, and expansion of these lesions. CLINICAL RELEVANCE: Understanding the pathogenesis of SCL will help to establish successful therapy in horses affected with SCL.  相似文献   
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Workouts of 980 unraced 2-year-old Thoroughbred racehorses at major U.S. auctions were videotaped using digital high-speed video equipment (ie, slow motion) and studied for signs of extraneous foreleg motion.a Extraneous foreleg motion included, but was not limited to: 1) hyper rotation of the cannon bone on an axis parallel to the plane of the running surface (ie, moving in sagittal plane; hoof hitting an elbow in extreme cases) and perpendicular to the direction of the racetrack longitudinally; and 2) foreleg flight patterns not symmetrical and/or not parallel to the vector of the forward momentum of the horse's center of gravity (eg, winging, paddling, and/or wobbling at joints). Experienced Thorough bred racehorse industry videographers and gait analysis researchers were trained and used as film reviewers who rated foreleg motion on a scale of 1 to 5, with 1 indicating little or no extraneous motion, 3.5 indicating average extraneous motion (relative to the other unraced 2-year-olds at these auctions and to more than 20,000 similar horses at similar auctions over the past 10 years), and 5 indicating extreme extraneous motion (ie, at least 1 standard deviation or more from the mean). Because these were subjective ratings, only the more extreme rankings were used for comparison purposes in this study—that is, a minority (15.3%) of the overall study population.

A group of 73 horses with “good” foreleg motion had ratings from 1 to 3. A group of 77 horses with “bad” foreleg motion had ratings from 4 to 5. The subsequent North American racing performance of horses with good and bad foreleg motion was compared. Both groups had similar average velocity and similar distribution patterns of the velocities of the workouts, so the differences between the groups that are discussed in this study were not caused by different overall workout velocities.

Extraneous foreleg motion was shown to be related to subsequent racing earnings and the level of racing competition achieved. Horses with good foreleg motion (as defined herein) earned more and had greater stakes-level success than horses with bad foreleg motion. For example, the median earnings per start of horses with good foreleg motion was 83% higher than those of horses with bad foreleg motion, and horses with good foreleg motion were 58% more likely to win a top race (ie, one designated as a “graded” stakes) than horses with bad foreleg motion. However, the “good movers” raced less overall than the “bad movers.”

A secondary finding of this study is that although there is a widely held industry belief that horses with high action or bad foreleg motion are more suited to turf racing, horses with good foreleg motion were more likely than horses with bad foreleg motion to race at least once on turf, and, among horses to race on turf, horses with good foreleg motion were more likely than horses with bad foreleg motion to win and to finish “in the money” (ie, at least third).  相似文献   

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基于AEZ模型的我国水稻产量潜力的农作制区划分析   总被引:1,自引:0,他引:1  
本文根据联合国粮农组织(FAO)和国际应用系统分析研究所(IIASA)基于中国1961~1997年的统计资料(经多方校正)共同开发的AEZ模型,运用G IS平台计算了中国41个农作制亚区的水稻生产潜力,并指出了单产最高潜力分布区域。研究结果表明:我国水稻的最高产量潜力大约将是目前产量的2倍。这对我国水稻高产育种及栽培具有重要参考意义。  相似文献   
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