全文获取类型
收费全文 | 1596篇 |
免费 | 121篇 |
国内免费 | 81篇 |
专业分类
林业 | 116篇 |
农学 | 95篇 |
基础科学 | 79篇 |
122篇 | |
综合类 | 654篇 |
农作物 | 29篇 |
水产渔业 | 66篇 |
畜牧兽医 | 581篇 |
园艺 | 13篇 |
植物保护 | 43篇 |
出版年
2024年 | 9篇 |
2023年 | 26篇 |
2022年 | 45篇 |
2021年 | 73篇 |
2020年 | 74篇 |
2019年 | 75篇 |
2018年 | 54篇 |
2017年 | 70篇 |
2016年 | 78篇 |
2015年 | 55篇 |
2014年 | 85篇 |
2013年 | 122篇 |
2012年 | 102篇 |
2011年 | 120篇 |
2010年 | 124篇 |
2009年 | 102篇 |
2008年 | 86篇 |
2007年 | 82篇 |
2006年 | 70篇 |
2005年 | 75篇 |
2004年 | 47篇 |
2003年 | 37篇 |
2002年 | 22篇 |
2001年 | 21篇 |
2000年 | 20篇 |
1999年 | 19篇 |
1998年 | 15篇 |
1997年 | 18篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 7篇 |
1993年 | 6篇 |
1992年 | 10篇 |
1991年 | 9篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 2篇 |
排序方式: 共有1798条查询结果,搜索用时 31 毫秒
91.
Sedative and analgesic effects of medetomidine in beagle dogs infected and uninfected with heartworm
Venugopalan C.S. Holmes E.P. Crawford M.P. Kearney M.J. Fucci V. 《Veterinary research communications》1998,22(2):97-106
The sedative and analgesic effects of medetomidine were evaluated in heartworm-infected (HW+) and uninfected (HW–) beagle dogs by intravenous (IV) and intramuscular (IM) administration of 30 µg/kg and 40 µg/kg doses, respectively. Posture, response to noise and the pedal reflex were monitored. A procedure for mock radiographic positioning was performed to evaluate its overall clinical use. Observation times were 0, 15, 30, 60, 90, 120 and 180 min. In addition, the times from injection until the dog could not stand on its feet (down time), from lateral to sternal recumbency (sternal recumbency time), and from sternal recumbency to rising again (rising time) were also noted.Medetomidine produced rapid sedation and analgesia by both routes. Down times for the IM and IV routes were similar, which verified the manufacturer's recommended doses. The HW+ dogs had shorter down times, probably owing to increased blood flow to the brain caused by adrenergic alpha-2 activity. Sternal recumbency and rising times did not differ between the groups, suggesting a similar metabolism. Sedation and analgesia were adequate for performing the procedure in all dogs. HW– dogs showed less resistance to handling during the procedure than HW+ dogs. Overall, medetomidine seems to be a suitable agent for short-term chemical restraint in dogs, even with subclinical heartworm infestation. 相似文献
92.
在12只绵羊按0.3mg/kg剂量硬膜外腔注射静松灵,观测了镇静镇痛作用的效应,并对血液气体和酸碱平衡状态的变化进行了定量分析,结果表明静松灵硬膜外腔注射的镇静镇痛效果明显,显效时间短,持续时间达120min,对体温,脉搏,呼吸与吸气量有显著作用(P〈0.05),对血液中氧分压,氧含量,氧饱和度,二氧化碳分压,剩余碱及碳酸氢盐的影响明显(P〈0.05),而对血液pH值和血红蛋白含量无显著影响。 相似文献
93.
鸡贫血病雏鸡ND免疫后局部免疫组织抗体生成细胞变化 总被引:1,自引:1,他引:0
对感染鸡贫血病毒(CAV)雏鸡新城疫(ND)疫苗免疫及其强毒攻击后局部免疫组织——盲肠扁桃体和哈德尔腺的IgA、IgG和IgM抗体生成细胞数量的动态变化进行了检测。结果发现,CAV感染雏鸡ND免疫后7、14、28d及新城疫强毒(vNDV)攻击后,上述免疫组织的三种抗体生成细胞数量均不同程度地低于未感染CAV的ND免疫对照雏鸡。其中盲肠扁桃体弥散区的IgA减少最为明显。表明CAV感染雏鸡消化道和呼吸道局部免疫组织对新城疫疫苗的体液免疫应答功能降低。新城疫强毒攻击后CAV感染ND免疫雏鸡的免疫保护率也明显低于未感染CAV的免疫对照雏鸡。 相似文献
94.
WU Hai-gang XU Guang-ke HU Jing LIU Jin-ni CHEN Qin-xi ZHANG Ying-bing JI Wan-min YI Ben-chi MA Yun 《中国畜牧兽医》2017,44(8):2523-2528
The purpose of this study was to evaluate the safety of the cefquinome sulfate liposomes by using the acute toxicity test, local irritation test and chronic toxicity test. The results showed that the LD50 of cefquinome sulfate liposomes was 639.73 mg/kg after intramuscular injection of its suspension and 95% confidence interval was 573.06 to 714.17 mg/kg. There was no significant stimulation to muscle. Subchronic toxicity test showed that the weight, haematological indexes and biochemical criterion of rabbits in variety dose had no significant difference compared with normal group (P>0.05). There was no visible pathological changes on the liver,kidney histology. According to pathological observation, the structure of liver and kidney were clear in treated and middle dose groups,but there existed disorganized hepatic cell cord in the liver and hemorrhag between glomerulopathy,tubulointerstitial and hepatic sinusoids in high dose group. All results proved that the cefquinome sulfate liposomes was safe and reliable based on the animal experiments. 相似文献
95.
讨论了局域网网络环境中的实时通信过程的模型。采用Windows的时间中断技术建立了通信过程中相应的几个模型:对话建立模型、数据发送与接收模型和对话结束模型,以便用于网络中的实时通信、实时演示和实时讨论。 相似文献
96.
张廷远 《信阳农业高等专科学校学报》2011,21(4):62-65
豫南乡土文化存在生存环境恶化、文化本体的内部生态基因萎缩、传承后继乏人、经费投入严重不足等问题。对豫南乡土文化遗产进行抢护和回归性建设,不仅可为新农村建设的可持续发展提供不竭的精神道德支持,也有利于构筑地方经济发展的新平台。实施豫南乡土文化的建设储备战略与运行战略将是对其抢护的重要对策。 相似文献
97.
《Journal of Sustainable Forestry》2013,32(3-4):105-121
Summary Despite an encouraging trend in North America of growing interest across a range of disciplines in non-timber forest products (e.g., this volume), NTFP harvesters' knowledge and practices continue to be poorly understood and undervalued, if not ignored, both by research scientists and forestland policy-makers and managers. This article explores why NTFP harvesting suddenly emerged in North America as an “issue” in the early 1990s. Drawing from a three-year study of chanterelle mushroom harvesters on the Olympic Peninsula Biosphere Reserve (Washington, USA), we discuss a variety of forces which intersected in this period to bring NTFP harvesting to wider attention. Unfortunately, harvesters continue to be excluded as knowledgeable actors in, if not legitimate co-managers of, temperate forest ecosystems, resulting in both passive and active harvester resistance to research and management, a devaluing of local harvesting traditions, and missed opportunities for collaboration. We reluctantly conclude that despite “New Forestry” co-management rhetoric, given existing institutional barriers and positivist scientific categories, NTFP workers will likely remain excluded from active roles in temperate forest research and management-contributing in turn to the ongoing legitimacy crisis of public and private forest management entities. 相似文献
98.
对安哥拉山羊及其级进杂交后代的生长发育、繁殖力、抗病性、采食习性等进行初步观察研究,结果表明:在试验场良好的饲养条件下,各代杂种羊生长发育正常,但繁殖力、抗病性、采食能力随级进杂交代数的增加有降低的趋势。据此,笔者认为,在陕北特定的生态经济条件下,培育毛用山羊新品种,级进杂交代数不宜太高,到F3代应停止级进,进行横交固定,而且在整个育种中,应始终注意饲养问题,以保证新品种培育成功。 相似文献
99.
在调查的基础上,探讨了国内地方图书馆古籍数字化资源的建设基本情况,并提出了地方图书馆古籍数字化资源建设的基本原则。 相似文献
100.
秦翠萍 《农业图书情报学刊》2009,21(5):179-180
图书馆永远是一种公益性文化教育机构。图书馆及其藏品作为一种公共物品,靠全民税收由政府兴办;图书馆作为一种知识实体,不可能全面实行有偿服务;图书馆作为向公众提供知识载体的场地之一,也不可能靠自身的知识劳务输出完善自我生存与发展。 相似文献