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   115篇
  免费   6篇
  国内免费   1篇
林业   4篇
农学   1篇
  4篇
综合类   38篇
农作物   1篇
水产渔业   5篇
畜牧兽医   66篇
园艺   1篇
植物保护   2篇
  2019年   2篇
  2017年   2篇
  2016年   6篇
  2015年   2篇
  2014年   2篇
  2013年   8篇
  2012年   2篇
  2011年   3篇
  2009年   2篇
  2008年   4篇
  2007年   2篇
  2006年   11篇
  2005年   2篇
  2004年   3篇
  2003年   5篇
  2002年   6篇
  2001年   3篇
  2000年   6篇
  1999年   2篇
  1998年   2篇
  1997年   2篇
  1996年   4篇
  1994年   2篇
  1993年   1篇
  1992年   2篇
  1991年   1篇
  1989年   1篇
  1988年   1篇
  1987年   2篇
  1985年   1篇
  1984年   1篇
  1979年   1篇
  1976年   1篇
  1974年   2篇
  1973年   1篇
  1972年   2篇
  1970年   1篇
  1969年   1篇
  1968年   2篇
  1966年   1篇
  1964年   1篇
  1963年   1篇
  1961年   1篇
  1960年   1篇
  1959年   2篇
  1949年   1篇
  1948年   1篇
  1939年   1篇
  1938年   2篇
  1937年   2篇
排序方式: 共有122条查询结果,搜索用时 46 毫秒
81.
Medical records of cats with high-rise trauma were reviewed to document the prevalence and clinical manifestations of orofacial injury. Cats were presented over a 10-year period from January 2000 to December 2009. Signalment, weight, number of stories fallen, and survival data were recorded in 84 cats and physical examination findings were obtained from 83 cats. Fourteen of these cats were examined by veterinarians of the Dentistry and Oral Surgery Service. Mean age was 37-months. Mean distance fallen was 2.65 stories, and in the majority of cases the substrate the cat fell on was not recorded Overall, survival was 94.0% when including euthanasia as a cause of death and 98.8% when excluding euthanized patients. Orofacial findings included bilateral epistaxis, hard palate fracture +/- tear of palatal soft tissue, palatal soft tissue bruising, mandibular fracture, mandibular symphyseal separation, tongue injury, facial soft tissue injury, dental trauma, and other oral soft tissue injury. Sixty-six percent of cats suffered some degree of orofacial injury. The population was analyzed for the prevalence of each type of injury. An oronasal fistula was seen in one cat as a complication of an untreated hard palate fracture. Possible etiology of the injuries and treatment options are discussed.  相似文献   
82.
83.
The green iguana, Iguana iguana, is used as a model in reptile anesthesia research because of its size, availability, and the body of knowledge characterizing its physiology. Arterial blood gas values in nonanesthetized green iguanas have not been determined because of the technical difficulty involved. Vascular access port (VAP) placement to facilitate blood sampling has been described in other species, but not lacertilians. This abstract describes the technique for placement of VAPs and the values for arterial blood gas parameters in seven 1 kg adult green iguanas. Using sterile technique, a 1.5 cm incision was made on the lateral side of the neck. Blunt dissection ventral to the external jugular vein revealed the internal and external carotid arteries near their bifurcation. The catheter was inserted into the internal carotid artery and then guided to the common carotid artery. The other end of the catheter was tunneled below the skin to a subcutaneous location, caudal‐dorsal to the iSPSilateral scapula. The skin was closed and the port was flushed twice a week with heparinized saline. Post‐operatively, the VAPs were well tolerated by the iguanas. Difficulties included port disconnection (n = 1), inability to aspirate blood after a few weeks (n = 2), and infection (n = 1). The iguanas were breathing room air prior to and during blood collection. From the five functional VAPs, the blood pH, PCO2, PO2, HCO3, and BE (measured at 37 °C) were 7.45 ± 0.06; 37.5 ± 7.0 mm Hg, 99.0 ±16.6 mm Hg, 25.4 ± 2.5 mmol L–1, and 1.5 ±2.4 mmol L–1 respectively (mean ± SD). VAPs can be successfully used to facilitate collection of arterial blood gas samples in green iguanas. These values are similar to those reported for most mammalian species. This technique should facilitate research in anesthesiology and respiratory physiology of iguanas and other lacertilians.  相似文献   
84.
在欧洲,环境是养猪业发展的主要限制因素.为了致力于养猪生产与环境之间关系的研究,法国的R&D所属的各个组织参与了Porcherie Verte项目的研究工作,这个项目中还包括基础应用的研究.参加这项研究工作的人员中包括养猪相关专业、金融界、基础科学、应用研究机构以及政府部门,另外还有农业及环保的代表、私人研究机构的代表以及非赢利的有关环境机构的代表参加.该项目历时4年,在2001-2005年期间,共有90名科学家参与了此项目,开展了52项研究.主要调查的内容包含经济学、社会学和法规学,以达到全面研究养猪生产与环境保护之间关系的目的.  相似文献   
85.
86.
87.
AIMS: To describe and evaluate the current practices used to manage and prevent facial eczema (FE) in North Island dairy herds, and determine the within-herd prevalence of cows with elevated activities of gamma glutamyl transferase (GGT), and with concentrations of Zn in serum <18?μmol/L.

METHODS: Between January and May 2014, 105 herd managers from throughout the North Island of New Zealand were invited to participate in the study when regional spore counts for Pithomyces chartarum started to rise towards 30,000 spores/g pasture. Managers selected 10 representative cattle that were weighed and blood-sampled by the herd veterinarian. Blood samples were analysed for concentrations of Zn in serum and GGT activity. Pasture samples were also collected and submitted for spore count estimation. Finally a survey of farm management practices relating to prevention of FE was completed by the herd manager. A mixed-effects logistic regression model was used to determine associations between herd-level and cow-level explanatory variables and the probability of a cow having a concentration of Zn in serum <18?µmol/L.

RESULTS: Of the 1,071 cows tested, 79 (7.3 (95% CI=5.8–9.0)%) had GGT activity in serum >300?IU/L, and 35/106 (33 (95% CI=24.2–42.8)%) herds had ≥1 of the 10 cows sampled with GGT activity >300?IU/L. Of the 911 cows that were being treated with Zn, concentrations of Zn were between 18–35?μmol/L in 398 (43.6 (95% CI=40.4–46.9)%) cows, were >35?μmol/L in 32 (3.5 (95% CI=2.4–4.1)%) cows, and <18?μmol/L in 479 (52.6 (95% CI=49.3–55.9)%) cows. After adjusting for the confounding effect of region, the odds of a cow having concentrations of Zn in serum <18?μmol/L were 5.5 (95% CI=1.1–29) times greater for cows supplemented with zinc in water compared with those supplemented by drenching. Of the 105 herd managers, 103 (98%) stated that they had access to regional spore count data, but only 35/105 (33%) reported that they measured spore counts on their own farm. Overall, 98/105 (93%) managers reported that they had some form of FE management programme in place. Fungicides were used on their own or in combination with zinc treatments in 10 herds, ZnSO4 in water troughs was used in 68 herds, oral drenching with ZnO in nine herds, and ZnO supplied in-feed in 26 herds. Estimated daily dose rates of zinc were less than that required to treat a 400?kg cow on 42/68 farms that administered ZnSO4 in the water or ZnO as a drench.

CONCLUSION AND CLINICAL RELEVANCE: This study has shown that FE management on dairy farms in the North Island of New Zealand could be substantially improved. It is likely that improved FE management would occur if herd managers were provided with more feedback on the success (or otherwise) of their FE management programmes.  相似文献   
88.
AIMS: To determine whether the application of lime or nitrogen to pasture affected the spore counts of Pithomyces chartarum.

MATERIALS AND METHODS: The lime application studies were undertaken on a spring-calving, pasture-based, commercial dairy farm near Te Awamutu, New Zealand. On 6 November 2012, five randomly selected paddocks were split into three equal sections. In two of the sections, lime was applied at either 1.5 or 2.5?t/ha, and the central section was left as an untreated control. Each section was sampled for spore counting weekly from 16 January to 15 May 2013.

Starting in January 2013, five other randomly selected paddocks were monitored for spore counts. On 20 March 2013 the average spore counts in three paddocks were >100,000 spores/g of pasture. These paddocks were then divided into three equal sections and lime was applied as described above. Spore counting in each section continued weekly until 15 May 2013.

The nitrogen application study was carried out on three commercial dairy farms near Te Awamutu, New Zealand. Two randomly selected paddocks on each farm were divided into three equal sections and, on 20 December 2012, nitrogen in the form of urea was applied at either 50 or 80?kg urea/ha to two of the sections; the central section remained as an untreated control. Each section was sampled for spore counting weekly from 16 January to 15 May 2013.

RESULTS: Following pre-summer lime application, treatment at 1.5 or 2.5?t/ha did not affect spore counts over time compared with the control section (p>0.26). Similarly following autumn lime application, treatment at 1.5 or 2.5?t/ha did not affect spore counts over time compared with the control section (p>0.11). Following nitrogen application median spore counts remained <20,000 spores/g pasture throughout the trial period and there was no effect of treatment on spore counts over time (p>0.49).

CONCLUSION: This study found that application of lime before the risk period for facial eczema, in November, application of lime after a spore count rise, in March, or urea application in December did not affect changes in number of spores produced by P. chartarum.

CLINICAL RELEVANCE: This study does not support previous suggestions that fertilising pasture with lime or urea could alter the spore counts of P. chartarum. Fertiliser use does not provide an alternative to, or support, conventional methods of facial eczema control such as zinc prophylaxis or treatment of pasture with fungicides.  相似文献   
89.
瓦庆荣 《草业科学》2008,25(3):18-21
石漠化问题加剧了喀斯特地区的水土流失和旱涝等自然灾害,进一步加深了该地区贫困程度,越来越成为制约社会、经济和生态全面发展的桎梏.恢复喀斯特地区草地植被是解决喀斯特地区石漠化问题的根本出路和保护生态环境的最后屏障,可以在快速有效地减少水土流失的同时短期内大幅度增加农民收入,实现可持续发展.恢复石漠化地区草地植被,要在保护和合理利用现有草地资源的基础上, 与种植优质牧草、发展草地畜牧业相结合, 与推广沼气技术相结合, 与生态旅游相结合.要拓宽投融资渠道, 增加资金投入.  相似文献   
90.
OBJECTIVE: To evaluate the effects on plasma cortisol concentration of a continuous infusion of a readily available steroid with equipotent glucocorticoid and mineralocorticoid effects. PROCEDURE: Plasma cortisol concentrations were measured before and regularly after hydrocortisone sodium succinate was administered as a continuous intravenous infusion over 6 h at 0.32 and 0.65 mg kg-1 h-1 to 12 healthy dogs weighing 12 to 22 kg. RESULTS: The infusion at both does rates produced significant and stable increases in plasma cortisol concentrations. The plateau concentrations produced by the large and small doeses were respectively above and below plasma cortisol concentrations likely to provide adequate glucocorticoid and mineralocorticoid activity in stressed dogs with significantly decreased adrenal function. CONCLUSION: This paper presents information regarding the changes in plasma cortisol concentrations in 12 normal dogs given an hydrocortisone sodium succinate infusion at two dose rates. The marked and continuous increase in plasma cortisol concentrations suggests a continuous HSS infusion may be a possible alternative to desoxycorticosterone acetate and dexamethasone in the treatment of acute adrenal dysfunction.  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