全文获取类型
收费全文 | 227篇 |
免费 | 13篇 |
国内免费 | 17篇 |
专业分类
林业 | 9篇 |
农学 | 14篇 |
基础科学 | 18篇 |
17篇 | |
综合类 | 34篇 |
农作物 | 2篇 |
水产渔业 | 4篇 |
畜牧兽医 | 153篇 |
园艺 | 6篇 |
出版年
2023年 | 3篇 |
2022年 | 12篇 |
2021年 | 10篇 |
2020年 | 18篇 |
2019年 | 14篇 |
2018年 | 8篇 |
2017年 | 9篇 |
2016年 | 6篇 |
2015年 | 6篇 |
2014年 | 6篇 |
2013年 | 16篇 |
2012年 | 11篇 |
2011年 | 13篇 |
2010年 | 11篇 |
2009年 | 7篇 |
2008年 | 7篇 |
2007年 | 11篇 |
2006年 | 6篇 |
2005年 | 16篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 6篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 6篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
排序方式: 共有257条查询结果,搜索用时 125 毫秒
191.
Tatiana H. Ferreira Leandro B.C. Teixeira Carrie A. Schroeder Cristina de Miguel Garcia Kristopher M. Schroeder 《Veterinary anaesthesia and analgesia》2018,45(6):811-819
Objectives
To describe an ultrasound-guided thoracic paravertebral block and determine the distribution after injection of two volumes of methylene blue in dog cadavers.Study design
Prospective experimental cadaveric study.Animals
Twelve dog cadavers weighing 11 ± 3 kg.Methods
Ultrasound-guided injections aimed at the fifth thoracic (T5) paravertebral space were performed in randomized order using 0.1 or 0.3 mL kg–1 dye solution (six dogs for each volume). Anatomic dissections determined dye spread characteristics, including the presence and degree of staining of spinal nerves, and the presence of intercostal and sympathetic trunk spread. Staining of mediastinum, epidural, intrapleural and contralateral thoracic paravertebral space was recorded.Results
There was no significant difference in dye distribution between groups. The use of anatomic landmarks resulted in the inaccurate identification of the T5 paravertebral space. The T4, T5 and T6 paravertebral spaces were injected in four, five and three of 12 dogs, respectively. Complete staining of the spinal nerve of the thoracic paravertebral space injected was observed in 11 of 12 dogs, and partial staining in one dog in the low-volume group. Multisegmental distribution was demonstrated with staining of contiguous spinal nerves in one dog in the high-volume group, and multiple segments of intercostal (three dogs) and sympathetic trunk (four dogs) spread in both groups. No mediastinal, epidural, intrapleural or contralateral thoracic paravertebral space staining was observed.Conclusions and clinical relevance
Ultrasound-guided injection at the thoracic paravertebral space resulted in staining of the spinal nerve in all dogs. However, T5 paravertebral space was not accurately identified using anatomic landmarks. Dye distribution was not significantly different between the two groups; therefore, the use of the lower-volume and multiple-site injections would be potentially necessary in clinical cases to achieve ipsilateral blockade of the thoracic wall. 相似文献192.
193.
Levi H. Smith Larry Adams Maxime Derré Wendy M. Townsend 《Veterinary ophthalmology》2023,26(3):256-261
Objective
To describe the successful use of endoscopy to visualize and place a soft canine ureteral stent to relieve a chronic nasolacrimal duct (NLD) obstruction in a horse.Animal Studied
A 7-year-old, Quarter horse gelding.Procedure
Under general anesthesia, retrograde nasolacrimal endoscopy was performed using an 8.5 Fr Storz Flex XC ureteroscope through the nasal punctum (NP). An obstructive web of fibrous tissue was visualized approximately 20 cm proximal to the NP. A 0.035″/150 cm hydrophilic guidewire was passed normograde from the ventral lacrimal punctum and used to puncture the stenotic tissue. Then, a 5.0Fr/70 cm open-end ureteral catheter was threaded normograde over the guidewire and NLD patency was re-established. The catheter confirmed a NLD length of 30 cm and was then removed. A 5.0Fr/22–32 cm Universa© Soft Ureteral Stent was threaded normograde over the guidewire until the loops of the stent were exposed at each end. The guidewire was removed and the stent loops were sutured in place.Results
The stent was withdrawn 1 month after the procedure. Telephone follow-up with the client reported significant improvement in the amount of ocular discharge and decreased sensitivity around the face and ears.Conclusion
Endoscopy is a safe and effective procedure allowing for definitive diagnosis of NLD obstruction and to assist in interventional procedures. Placement of a canine indwelling ureteral stent seems to be an effective alternative treatment option for equine NLD obstruction compared to conventional invasive surgical procedures. 相似文献194.
风道的合理设计,可降低通风空调系统噪声。合理选择风机,可有效降低运行费用,以达到整个系统运行经济性提高运行效果。 相似文献
195.
果园喷雾机单双风机风道气流场仿真与试验 总被引:6,自引:6,他引:0
针对单风道果园喷雾机两侧气流场不对称、施药不均匀的现象,对自制双风道果园风送试验台气流场特性进行分析研究。该文采用CFD数值模拟和试验的方法对单双风道的气流场由内及外依次对比分析研究,以viscous-standard模型分析单双风道内部气流场分布,对仿真值与试验值拟合分析,拟合优度R2=0.8274,验证数值模拟的准确性;通过对两风道出风口及距出风口不同截面上的风速散点数据Golden software Voxler拟合处理和加权分析对比2种风道特性。结果显示:单风道内部流场右侧较强,双风道左右两侧基本一致;双风道在出风口处风速较单风道大,且两侧风速曲线走势基本相同;两侧距出风口0、1、2、3、4、5 m截面上外部气流场气流分布云图中,单风道气流场集中域有明显的偏移,两侧气流场强度差异大,双风道左右气流场基本对称;在对中性上,2 m截面上双风道左右两侧最大风速对其距中距离的加权平均数分别为-3.23、-1.33 mm,单风道为-24.99、-32.33 mm,且双风道距中偏移量随距离的变化趋势较单风道小。综合分析最终得到双风道气流场在两侧对称性和对中性上较单风道有明显的优势。该研究可为进一步优化风送喷雾技术提供参考。 相似文献
196.
Gordon D. Peddle VMD Carol A. Carberry DVM DACVS Justin M. Goggin DVM DACVR 《Journal of Veterinary Emergency and Critical Care》2008,18(6):631-638
Objective– To describe the diagnosis and successful treatment of bile pleuritis and peritonitis secondary to traumatic rupture of the common bile duct and a diaphragmatic tear in a young dog. Case Summary– A 1‐year‐old German Shepherd dog was referred for evaluation of vomiting and icterus 4 days after being hit by a car. Thoracic radiographs, thoracic and abdominal ultrasonographic examinations, thoraco‐ and abdominocentesis, and positive contrast celiogram indicated hemorrhagic pleuritis and peritonitis, left dorsal diaphragmatic tear, and rupture and infarct of the spleen. Surgical exploration of the abdomen confirmed these findings in addition to a circumferential tear of the common bile duct, leading to a diagnosis of hemorrhagic bile pleuritis and peritonitis. Aerobic and anaerobic bacterial culture of the abdominal fluid yielded no growth. Surgical correction of the traumatic injuries was achieved via common bile duct anastomosis, cholecystojejunostomy, repair of the diaphragm, and splenectomy. The dog developed postoperative signs consistent with aspiration pneumonia but was successfully treated and discharged from the hospital. Clinical signs and laboratory abnormalities resolved and the dog was alive and healthy 8 months after discharge. New or Unique Information Provided– Bile pleuritis is rare in dogs and cats and is usually associated with penetrating, not blunt, abdominal trauma. Multiple organ injury in cases of traumatic bile duct rupture is uncommon; in this dog, rupture of the common bile duct was accompanied by rupture of the diaphragm and spleen. 相似文献
197.
针对传统果园多风机风送喷雾机存在风能利用率低,出风口到靶标之间喷雾四散飘移的问题,对风机配置聚风筒(直筒式、渐缩式、渐开式)的风送喷雾系统的聚风喷雾性能进行研究。通过对聚风筒风场进行仿真模拟,设计对标试验确定了仿真模型与计算的可靠性。设计单因素试验和响应面参数优化试验分析风筒类型、聚风筒长度和风机转速对聚风特性的影响并确定聚风筒的最佳参数设计组合。试验结果表明:有聚风筒的风送喷雾系统对雾滴的胁迫作用明显显著优于无风筒的,且呈现了较好的聚风雾化作用,渐缩式风筒的性能尤为明显;气流集中性能由高到低排序为渐缩式、直筒式、渐开式、无风筒,聚风筒胁迫雾滴的横向穿透性能由高到低为渐缩式、直筒式、渐开式;风筒长度在30~70cm范围内,长度越长,聚风性能越好;随着转速呈倍数的增加,风场速度峰值也呈倍数增加,转速的改变不影响速度峰值的位置。聚风筒最佳参数设计组合为风筒类型为渐缩式,风筒长度为70cm,风机转速1 440r/min,此组合下的风速为4.156m/s,风场纵向幅宽为1 585.32mm。 相似文献
198.
汽车空调的风道结构影响出风口风量的分配、气流的走向,从而影响汽车的除霜性能。基于Realizable K-ε湍流模型,对于汽车的风道结构与内部流场进行数值研究,同时,利用实验验证了数值研究的准确性。首先建立带有风道的整车模型,然后对汽车除霜过程进行了仿真,发现不合理的风道结构影响除霜效率;然后对汽车空调的风道结构进行改进,汽车除霜效率得到极大提高,B区除霜死角的面积由20%降到了5%。 相似文献
199.
200.
A 130-week-old male Royal College of Surgeons rat kept as a non-treated animal in a long-term animal study presented with a mass in the hepatic portal region that adhered to a dilated common bile duct and the duodenum. Histopathologically, the solitary mass showed expansive growth with no apparent compression and continued to dilate the common bile duct, which had a hyperplastic epithelium with intestinal metaplasia. The mass mainly consisted of small to large dilated and/or tortuous ducts with abundant dense connective tissue and many inflammatory cells. The single-layer lining epithelium of the duct changed from cuboidal to columnar. Immunohistochemically, the lining cells were positive for cytokeratin 7, cytokeratin 19, and OV-6, which are bile duct markers. Based on the pathological characteristics, the rat was diagnosed as spontaneous cholangiofibrosis adjacent to a dilated common bile duct with intestinal metaplasia. 相似文献