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   200篇
  免费   27篇
农学   1篇
综合类   8篇
农作物   1篇
水产渔业   2篇
畜牧兽医   212篇
园艺   1篇
植物保护   2篇
  2023年   1篇
  2020年   5篇
  2019年   4篇
  2018年   7篇
  2017年   7篇
  2016年   15篇
  2015年   5篇
  2014年   7篇
  2013年   15篇
  2012年   1篇
  2011年   2篇
  2010年   10篇
  2009年   5篇
  2008年   6篇
  2007年   1篇
  2006年   9篇
  2005年   2篇
  2004年   6篇
  2003年   2篇
  2002年   2篇
  2001年   5篇
  2000年   3篇
  1999年   11篇
  1998年   13篇
  1997年   14篇
  1996年   13篇
  1995年   5篇
  1994年   1篇
  1993年   8篇
  1992年   3篇
  1991年   3篇
  1990年   3篇
  1989年   8篇
  1988年   9篇
  1987年   1篇
  1986年   3篇
  1985年   1篇
  1984年   1篇
  1979年   2篇
  1978年   1篇
  1977年   3篇
  1976年   1篇
  1974年   1篇
  1973年   1篇
  1960年   1篇
排序方式: 共有227条查询结果,搜索用时 15 毫秒
131.
132.
133.
134.
Effect of cimetidine on aspirin-induced gastric hemorrhage in dogs   总被引:1,自引:0,他引:1  
Efficacy of cimetidine in the prevention of aspirin-induced gastric hemorrhage was evaluated, using 4 groups of 6 dogs given: Group 1--controls; group 2-7.5 mg of cimetidine/kg of body weight every 8 hours; group 3-7.5 mg of cimetidine/kg every 8 hours and 35 mg of nonbuffered aspirin/kg every 8 hours; and group 4-35 mg of nonbuffered aspirin/kg every 8 hours. All medication was given orally for 10 days at the time of feeding a commercial dry food. The gastric mucosa was evaluated endoscopically before treatment, on treatment day 5, and 36 hours after the final treatment. The dogs were given halothane inhalation anesthesia and were evaluated, using a grading system. Total 24-hour fecal hemoglobin (Hb) concentration was measured, using a quantitative fluorometric analysis for Hb-derived porphyrins. Control dogs and dogs given cimetidine only had no endoscopically visible gastric lesions and no increase in fecal Hb concentration. All dogs given aspirin or aspirin and cimetidine had a similar marked increase in endoscopically visible gastric hemorrhage and marked increases in fecal Hb concentration; however, there was no significant (P = 0.48) difference between the 2 groups. Seemingly, cimetidine given at an oral dosage of 7.5 mg/kg every 8 hours was not effective in preventing aspirin-induced gastric hemorrhage in clinically normal dogs.  相似文献   
135.
136.
137.
138.
Computer-automated sperm-head morphometry was used in this study to determine the effects of cryopreservation on red deer sperm-head morphometry. Epididymal sperm samples were collected from 40 mature stags and were divided. One portion was diluted at room temperature in a Tris-citrate egg yolk medium, containing 6% glycerol. A microscope slide was prepared from single extended sperm samples prior to freezing. The remainder of each sample was frozen in nitrogen vapours. After thawing, sperm smears were prepared as described above. All slides were air dried and stained with Hemacolor. The sperm-head dimensions for length, width, area, perimeter and shape factor (length/width), for a minimum of 135 spermatozoa were determined for each slide by means of the Sperm-Class Analyser (SCA). Firstly, our results show that cryopreservation substantially reduced (p < 0.001) sperm motility and plasma membrane and acrosome integrities. In addition, sperm heads were significantly smaller in cryopreserved spermatozoa than in the companion extended samples for area (32.05 microm2 vs 32.56 microm2; p < 0.05), length (8.46 microm vs 8.53 microm; p < 0.0001) and shape factor (1.833 vs 1.849; p < 0.0001) for all stags. These differences were found within 29 of 40 stags (75%) for at least three of the morphometric parameters. The individual variability (CV) of sperm head measurements from extended samples was negatively correlated (p < 0.005) with the per cent of change in sperm head measurements after cryopreservation for area (r = -0.465), width (r = -0.483) and perimeter (r = -0.375). Thus, the lower the sperm head variability in the extended samples, the greater the sperm change as a consequence of the cryopreservation. These results suggest that the variability (heterogeneity) in sperm head dimensions of individual stags may be a good indicator of sperm freezability.  相似文献   
139.
CF Chou  AJ Jin  SW Hui  CC Huang  JT Ho 《Science (New York, N.Y.)》1998,280(5368):1424-1426
An unexpected three-stage melting transition has been observed in two-dimensional (2D) free-standing liquid-crystal films by in situ electron-diffraction and optical-reflectivity measurements. These data suggest the existence of two phases between the 2D solid and liquid: a hexatic phase and, at a higher temperature, an intermediate liquid phase with hexatic-like positional correlations ( approximately 40 angstroms) but no long-range orientational order. Previous high-resolution heat-capacity measurements have revealed a divergent-like anomaly at the hexatic-liquid transition that sharply contradicts the predictions of 2D melting theories. The observation of an intermediate isotropic phase may alter our understanding of 2D melting and lead to reconciliation between current experiments and theories.  相似文献   
140.
Complications associated with equine castration are the most common cause of malpractice claims against equine practitioners in North America. An understanding of the embryological development and surgical anatomy is essential to differentiate abnormal from normal structures and to minimise complications. Castration of the normal horse can be performed using sedation and regional anaesthesia while the horse is standing, or under general anaesthesia when it is recumbent. Castration of cryptorchid horses is best performed under general anaesthesia at a surgical facility. Techniques for castration include open, closed and half-closed techniques. Failure of left and right testicles to descend occurs with nearly equal frequency, however, the left testicle is found in the abdomen in 75% of cryptorchid horses compared to 42% of right testicles. Bilateral cryptorchid and monorchid horses are uncommon. Surgical approaches described for the castration of cryptorchid horses include an inguinal approach with or without retrieval of the scrotal ligament, a parainguinal approach, or less commonly a suprapubic paramedian or flank approach. Laparoscopic castration of cryptorchid horses has recently been described but the technique has limited application in practice at this time. A definitive diagnosis of monorchidism can only be made after surgical exploration of the abdomen, removal of the normal testis and hormonal testing. Hormonal assays reported to be useful include analysis of basal plasma or serum testosterone or oestrone sulphate concentrations, testosterone concentrations following hCG stimulation, and faecal oestrone sulphate concentrations. Reported complications of castration include postoperative swelling, excessive haemorrhage, eventration, funiculitis, peritonitis, hydrocele, penile damage and continued stallion-like behaviour.  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