全文获取类型
收费全文 | 389篇 |
免费 | 37篇 |
专业分类
10篇 | |
综合类 | 5篇 |
农作物 | 3篇 |
水产渔业 | 1篇 |
畜牧兽医 | 392篇 |
植物保护 | 15篇 |
出版年
2023年 | 8篇 |
2021年 | 3篇 |
2020年 | 19篇 |
2019年 | 1篇 |
2018年 | 13篇 |
2017年 | 13篇 |
2016年 | 5篇 |
2015年 | 7篇 |
2014年 | 17篇 |
2013年 | 16篇 |
2012年 | 15篇 |
2011年 | 12篇 |
2010年 | 20篇 |
2009年 | 21篇 |
2008年 | 21篇 |
2007年 | 11篇 |
2006年 | 12篇 |
2005年 | 9篇 |
2004年 | 9篇 |
2003年 | 11篇 |
2002年 | 11篇 |
2001年 | 5篇 |
2000年 | 7篇 |
1999年 | 6篇 |
1998年 | 15篇 |
1997年 | 12篇 |
1996年 | 14篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 11篇 |
1992年 | 11篇 |
1991年 | 15篇 |
1990年 | 16篇 |
1989年 | 16篇 |
1988年 | 8篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 2篇 |
排序方式: 共有426条查询结果,搜索用时 15 毫秒
131.
通常情况下,管道涂敷商在涂敷新涂层之前,都要将管道表面处理到Sa 2.5级或者近白级,但是在施工现场却很难达到这一标准.讨论了旧涂层去除的常规方法、表面处理以及可预见的结果,并讨论了当前在表面处理方面的研究成果以及在涂层涂敷过程中二次生锈的各种影响. 相似文献
132.
133.
134.
135.
136.
137.
Marco QuartuccioGabriele Marino BS PhD RU Antonina ZanghìGiuseppe Garufi DVM Santo Cristarella DVM PO 《Journal of Equine Veterinary Science》2011,31(3):143-146
A careful evaluation of daily sperm output (DSO) and seminal parameters is indicative of the potential fertility of the animal and at the same time is useful for maximization of the reproductive activity. The aim of this article was to evaluate the seminal parameters, testicular volume (TV) calculated by ultrasound measurements, DSO, and any eventual relationship between these in Ragusano donkey jackasses. Eight Ragusano donkey stallions underwent a morphometric evaluation of the testes by ultrasound to calculate the TV, and daily semen collection for 10 consecutive days. TV ranged from 250 to 500 cm3 and no significant differences could be observed between the left and right testes. Only ejaculates from 4 to 10 days were analyzed, given that there was evidence that the sperm extragonadal reserve interfered with the total number of sperm in ejaculates during the early days. DSO in the Ragusano donkey ranged from 7 to 23 × 109 sperms. The seminal parameters showed high values of motility, viability, and low abnormality percentages. Age, TVs, and sperm parameters were not significantly correlated. The correlation between TV and DSO was poor (P = .1) in this study and this may suggest that TV and DSO might simply not be highly correlated in the donkey. 相似文献
138.
Abigail L. Scherer-Hoock BS Elizabeth A. Greene PhD Michael Lennox BS Clarissa Brown-Douglas PhD 《Journal of Equine Veterinary Science》2011,31(4):180-184
Despite being largely studied as models of equine nutrition, few published data exist on actual nutritional requirements of Miniature horses. Small equines are particularly prone to obesity, insulin resistance, and the metabolic disorders for which these are risk factors. Improper feed rationing, overfeeding in particular, puts horses at risk for these metabolic problems. Feed manufacturers, however, generally supply feeding recommendations for horses weighing ≥360 kg, whereas the average Miniature horse weighs around 100 kg. Lack of nutritional guidelines for small equines makes it difficult for owners to properly estimate the amount of hay and grain to feed their Miniature horse. The purpose of this study was to determine whether feeding recommendations provided by feed manufacturers for average-sized horses could be linearly extrapolated to Miniature horses. This study surveyed nutritional management of 12 mature Miniature horses that represented the ideal body condition of the breed. Each horse’s hay, grain, and pasture intake was recorded and the average daily digestible energy (DE) intake was calculated from those data. The daily DE intake of the surveyed horses was compared with the extrapolated recommendations published by several different sources. When linearly extrapolated to fit the body weight of a Miniature horse, recommendations significantly (P < .002) misestimated the amount of daily DE that the surveyed horses were consuming. The majority of recommendations overestimated the DE consumed by the Miniature horses per day. However, one source that was designed specifically for Miniature horses, severely (P < .001) underestimated their required DE. 相似文献
139.
Krista B. Halling DVM John P. Graham MVB MSc Susan P. Newell DVM MS Gary W. Ellison DVM MS Carol J. Detrisac DVM PhD Frank G. Martin PhD James M. Vangilder BS Daniel Grossman DVM 《Veterinary radiology & ultrasound》2003,44(6):707-713
The sonographic features of acute renal allograft rejection in humans and dogs are manifested by increase in renal cross-sectional area and reduction in renal cortical blood flow. These changes have not been investigated in cats. The objectives of this study were to evaluate sonographic and scintigraphic changes during acute renal allograft rejection in cats. Eight SPF, intact, adult, male cats received heterotopic renal allotransplantations. Immunosuppressive doses of cyclosporine and prednisolone were administered for 14 days and then discontinued to allow acute allograft rejection to occur. Serial measurements of renal cross-sectional area, resistive index (RI), echogenicity, and glomerular filtration rate (GFR) were performed to evaluate changes during acute rejection. Upon sonographic confirmation of absent diastolic blood flow or a 20% increase in cross-sectional area of the allograft, a nephrectomy and histopathologic evaluation were performed. Acute allograft rejection was confirmed histologically in all cats. Significant increases in renal cross-sectional area (P < 0.001) occurred postoperatively and during rejection. There were no significant changes in RI (P = 0.43) at any time. A subjective increase in medullary echogenicity and a decrease in corticomedullary demarcation were observed in the rejection period. While GFR decreased significantly in the immediate postoperative period (P < 0.001), no further change occurred during rejection (P = 0.42). Changes in RI and GFR do not appear to be sensitive indicators of acute renal allograft rejection in cats. Serial measurements of renal cross-sectional area appear to be a sensitive method for the early diagnosis of allograft rejection in feline renal transplant recipients. 相似文献
140.
Thomas G. Nyland DVM Paul E. Fisher BS Mark Doverspike DVM William J. Hornof DVM MS Harvey J. Olander DVM PhD 《Veterinary radiology & ultrasound》1993,34(5):348-352
The ability of duplex Doppler ultrasonography to assist with the diagnosis of urinary tract obstruction was investigated in a study of 5 dogs with surgically induced, unilateral ureteral obstruction. The resistive index (RI) of obstructed kidneys was compared to that of controls and to the contralateral unobstructed kidneys. The RI was also evaluated following relief of obstruction. On the basis of an RI measurement ≥0.70 indicating obstruction, a sensitivity of 73% and a specificity of 77% was determined for the diagnosis of obstruction with Doppler ultrasonography. Although mean RI was elevated in obstructed kidneys compared to controls, it was concluded that a high false-negative rate (27%) limits the clinical usefulness of Doppler ultrasonography for the detection of urinary obstruction in dogs. The RI difference between obstructed and nonobstructed kidneys was also evaluated within individual animals, but the magnitude of difference between kidneys did not significantly improve the detection rate for obstruction. 相似文献