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   128篇
  免费   28篇
  国内免费   3篇
林业   3篇
农学   2篇
  3篇
综合类   20篇
农作物   2篇
水产渔业   4篇
畜牧兽医   117篇
园艺   2篇
植物保护   6篇
  2021年   1篇
  2020年   2篇
  2019年   1篇
  2018年   1篇
  2017年   3篇
  2016年   5篇
  2015年   1篇
  2014年   1篇
  2013年   4篇
  2012年   3篇
  2011年   4篇
  2010年   6篇
  2009年   3篇
  2008年   9篇
  2007年   3篇
  2006年   9篇
  2005年   5篇
  2004年   4篇
  2003年   6篇
  2002年   5篇
  2001年   6篇
  2000年   2篇
  1999年   3篇
  1998年   2篇
  1997年   3篇
  1996年   1篇
  1995年   2篇
  1994年   4篇
  1993年   4篇
  1992年   4篇
  1991年   5篇
  1990年   8篇
  1989年   10篇
  1988年   5篇
  1987年   8篇
  1986年   5篇
  1985年   3篇
  1983年   2篇
  1982年   2篇
  1981年   1篇
  1975年   1篇
  1974年   1篇
  1973年   1篇
排序方式: 共有159条查询结果,搜索用时 15 毫秒
151.
Right paramedian abomasopexy and right paralumbar fossa omentopexy appear to be the most widely used means of correcting left displacement of the abomasum in dairy cattle. We compared these two procedures in a prospective study of 101 cows with uncomplicated left displaced abomasum. The surgical treatment (right paramedian abomasopexy, n = 48; or right paralumbar fossa omentopexy, n = 53) was assigned randomly. Follow-up information was obtained, at regular intervals, from one week through six months following discharge from the hospital. Milk production, reproductive performance, surgical complications, and length of time retained in the herd after surgery were obtained for each animal. There was a trend in favor of the abomasopexy group in the one-month milk yield. There were no differences between procedures either in incisional complications, other problems noted at follow-up, or in the proportion dead/culled. Based on the milk yield at one month after surgery, we concluded that there may be a slight advantage to right paramedian abomasopexy in cows with uncomplicated left displaced abomasum.  相似文献   
152.
OBJECTIVE: To determine the outcome of horses with "complex" digital tenosynovitis treated by tenoscopic proximal annular ligament desmotomy and resection of synovial masses or adhesions, or both, within the digital sheath. STUDY DESIGN: Retrospective evaluation. ANIMALS OR SAMPLE POPULATION: Twenty-five horses with a clinical and ultrasonographic diagnosis of palmar or plantar proximal annular ligament constriction and ultrasonographic evidence of synovial masses or adhesions within the digital tendon sheath. METHODS: Each horse had tenoscopic surgery for annular ligament desmotomy combined with adhesiolysis and/or synovial mass resection. Mean follow-up time was 3.4 years. Spearman's rank correlation was used to assess the relationship between functional outcome or cosmetic results and preoperative variables including duration of clinical signs, digital sheath synovial fluid total protein concentration and nucleated cell count, thickness of the palmar or plantar proximal annular ligament (PAL), severity of adhesions, severity of synovial masses, degree of synovial distention, or limb affected. RESULTS: A total of 18 (72%) horses returned to athletic soundness, 4 were improved but not sound, and 3 were not improved. Cosmetic outcome was normal in 10 horses, improved but not normal in 12, and not improved in 3 horses. Cosmetic and functional outcome were significantly adversely affected by the duration of clinical signs and the severity of synovial masses. CONCLUSIONS: With appropriate tenoscopic surgical attention, horses with complex tenosynovitis syndrome characterized by synovial masses, adhesions, or both adhesions and masses, and PAL constriction, have a good prognosis for return to athletic soundness. CLINICAL RELEVANCE: Horses with PAL constriction and additional digital tendon sheath pathology such as adhesions and synovial masses have a 72% chance of returning to sound athletic performance, however 60% of horses retain some degree of cosmetic blemish in the affected limb. There is an inverse relationship between the duration of clinical signs and outcome, and therefore, prompt surgical attention is advised.  相似文献   
153.
OBJECTIVE: To compare postoperative complications, short- and long-term survival, and surgical times for hand-sewn end-to-end (EE), stapled functional end-to-end (FEE), and stapled side-to-side (SS) anastomotic techniques for jejunal resection in horses. DESIGN: Retrospective study. ANIMALS: 59 horses. PROCEDURE: Medical records were reviewed to obtain signalment, diagnosis, treatment, and outcome for horses that underwent jejunojejunostomy in our hospital. Only horses that recovered from anesthesia were included in the study. RESULTS: Among the 59 horses, there were 33 EE, 15 FEE, and 11 SS anastomoses. No difference was found in duration of surgery among the 3 techniques. The most common postoperative complications were colic episodes (56%), ileus (53%), diarrhea (20%), and adhesions (15%). Horses with SS anastomosis had a significantly shorter duration of postoperative ileus than the EE group did. No significant difference in duration of postoperative ileus was found among the other groups. No difference was found among the 3 anastomotic techniques in regard to survival rate at the time of discharge, 6 months after surgery, or 1 year after surgery. Overall survival rates after jejunal anastomosis were 88% at the time of discharge, 65% at 6 months after surgery, and 57% at > or = 1 year after surgery. CONCLUSIONS AND CLINICAL RELEVANCE: The hand-sewn EE, stapled FEE, and stapled SS anastomotic techniques should be considered equivalent methods for small intestinal anastomosis in the horse. However, the stapled SS technique may be preferred because of possible decreased duration of postoperative ileus.  相似文献   
154.
OBJECTIVE: To determine whether preoperative epidural administration of morphine and detomidine would decrease postoperative lameness after bilateral stifle arthroscopy in horses. STUDY DESIGN: Prospective clinical controlled study. ANIMALS: Eight adult horses that had bilateral arthroscopic procedures, including drilling of cartilage and subchondral bone within the femoropatellar joints. METHODS: Horses were randomly separated into 2 groups. Preoperatively, 4 horses were administered a combination of epidural morphine (0.2 mg/kg) and detomidine (30 microg/kg), and 4 horses were administered an equivalent volume of epidural saline (0.9% NaCl) solution. Postoperative pain was assessed using 6 video recordings made at hourly intervals of each horse at a walk. Assessments began 1 hour after recovery from anesthesia. The recordings were scrambled out of sequence and evaluated by 3 observers, unaware of treatment groups, who scored lameness from 0 to 4. Lameness scores of the 2 groups of horses were compared using a Wilcoxon's rank sum test. Heart and respiratory rates were also measured at each hourly interval and compared between groups using a repeated-measures ANOVA; statistical significance was set at P <.05. RESULTS: Preoperative administration of epidural morphine and detomidine significantly decreased lameness and heart rates after bilateral stifle arthroscopy. The greatest decrease was detected at hours 1 and 2 after recovery from anesthesia. CONCLUSION: We conclude that horses undergoing a painful arthroscopic procedure of the stifle joint benefit from the administration of preoperative epidural morphine and detomidine. CLINICAL RELEVANCE: Preoperative epidural administration of detomidine and morphine may be useful in decreasing postoperative pain after stifle arthroscopy as well as pain associated with other painful disorders involving the stifle joint, such as septic arthritis and trauma.  相似文献   
155.
Over an 8-year period, 9 horses with septic pedal osteitis were admitted to the New York State College of Veterinary Medicine. Septic pedal osteitis was defined by the presence of purulent exudate combined with radiographic evidence of lysis of the distal phalanx. The condition described involved only the distal phalanx, the laminae and hoofwall, and the soft tissues of the sole. Treatment included curettage and removal of the affected portion of the distal phalanx through a ventral approach to the foot, combined with systemic administration of antibodies. Of the 9 horses, 7 returned to soundness and original function within 12 weeks after surgery. During the early postoperative period, 2 horses died from causes unrelated to the surgery or to septic pedal osteitis.  相似文献   
156.
实时实地氮肥管理对水稻产量和氮素利用率的影响   总被引:117,自引:12,他引:117  
 以籼型三系杂交稻汕优 63为材料 ,对不同氮肥管理的农艺和经济表现进行了评价。结果表明 ,未施氮肥 (空白区 )的产量为 6.8~ 7.4t·ha- 1,表明试验田背景氮颇高。与农民习惯施肥法 (氮肥 2 40kg·ha- 1)相比 ,改良的农民施肥法 (农民习惯施氮量的 70 % )、实时氮肥管理 (依据叶绿素仪测定值进行的施肥方法 )和实地氮肥管理(施氮时期、施氮量和叶绿素仪测定值相结合的施肥方法 )分别增产 9.2 %~ 10 .3 %、3 .3 %~ 7.0 %和 8.9%~ 9.3 % ,氮肥农学利用率分别提高了 110 .5%~ 13 5.6%、2 0 4.3 %~ 2 97.0 %和 2 0 0 .9%~ 2 76.4%。以上结果表明 ,在产量不降低甚至有所增加的前提下 ,实时、实地氮肥管理可以减少氮肥施用量 ,较大幅度地提高水稻氮肥利用率。另外 ,实时、实地氮肥管理还可以降低稻米的垩白率和垩白度 ,改善稻米的外观品质  相似文献   
157.
A 8‐week feeding trial was conducted to determine the effect of substituting fish oil with palm oil‐laden spent bleaching clay (SBC), a by‐product from crude palm oil (CPO) refining, on growth, feed utilization, fatty acid composition and heavy metal accumulation in the muscle of Nile tilapia, Oreochromis niloticus. Four isonitrogenous and isolipidic practical diets were formulated to contain 0, 100, 200 or 300 g kg?1 SBC. Growth performance of Nile tilapia was significantly better in fish fed the 100 g kg?1 SBC diet compared with fish fed the 0, 200 or 300 g kg?1 SBC diet. Growth and feed utilization efficiency of fish fed 200 or 300 g kg?1 SBC were similar to fish fed the control diet without added SBC. Whole‐body composition, body‐organ indices and haematocrit of tilapia were not affected by dietary treatments. Fatty acid compositions in the muscle lipid of Nile tilapia were strongly influenced by dietary treatments with progressively elevated levels of total saturates and n‐6 PUFA because of the dietary influence of these fatty acids from residual CPO adsorbed onto SBC. A gradual decrease in total n‐3 PUFA concentrations were also observed with the ratio of n‐3 to n‐6 fatty acids in muscle lipids decreasing from 4.75 to 4.41, 3.23 or 2.37 after 8 weeks on the 0, 100, 200 or 300 g kg?1 SBC diet, respectively. The arsenic, cadmium and lead concentrations in the experimental diets increased with increasing dietary levels of SBC but the concentrations of these heavy metals in the whole body and bone of Nile tilapia were not significantly different among fish fed the various diets. The present 8‐week study showed that in fishmeal‐based diets for Nile tilapia, palm oil‐laden SBC can totally replace added fish oil. The use of this presently discarded waste product from palm oil refining in tilapia diets will greatly contribute to reducing the impact of rising feed costs in the culture of tilapia in many tropical countries. Other potential benefits may include acting as a feed binder, removal of mycotoxins in fish feeds as well as adsorbing toxic substances present in the culture water.  相似文献   
158.
The electrical properties of individual bundles, or "ropes," of single-walled carbon nanotubes have been measured. Below about 10 kelvin, the low-bias conductance was suppressed for voltages less than a few millivolts. In addition, dramatic peaks were observed in the conductance as a function of a gate voltage that modulated the number of electrons in the rope. These results are interpreted in terms of single-electron charging and resonant tunneling through the quantized energy levels of the nanotubes composing the rope.  相似文献   
159.
对北京市城区和近郊区的新鲜城市生活垃圾进行了分类调查和理化性质测定。结果表明:(1)新鲜生活垃圾可农用部分占84.04%,冬季可农用部分所占比率高;(2)垃圾肥料有机质含量在12.50%—19.70%范围,全氮在0.53%—0.87%范围;(3)垃圾肥料重金属含量和残毒含量符合国家卫生标准和城市垃圾农用控制标准。建议垃圾肥料与处理过的禽畜粪便混合,可生产出优质有机肥料。  相似文献   
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