全文获取类型
收费全文 | 1828篇 |
免费 | 104篇 |
国内免费 | 430篇 |
专业分类
林业 | 180篇 |
农学 | 184篇 |
基础科学 | 46篇 |
201篇 | |
综合类 | 706篇 |
农作物 | 195篇 |
水产渔业 | 240篇 |
畜牧兽医 | 445篇 |
园艺 | 78篇 |
植物保护 | 87篇 |
出版年
2024年 | 13篇 |
2023年 | 26篇 |
2022年 | 18篇 |
2021年 | 26篇 |
2020年 | 32篇 |
2019年 | 26篇 |
2018年 | 44篇 |
2017年 | 47篇 |
2016年 | 68篇 |
2015年 | 38篇 |
2014年 | 77篇 |
2013年 | 136篇 |
2012年 | 136篇 |
2011年 | 134篇 |
2010年 | 157篇 |
2009年 | 81篇 |
2008年 | 88篇 |
2007年 | 72篇 |
2006年 | 73篇 |
2005年 | 63篇 |
2004年 | 72篇 |
2003年 | 157篇 |
2002年 | 290篇 |
2001年 | 205篇 |
2000年 | 164篇 |
1999年 | 57篇 |
1998年 | 5篇 |
1997年 | 9篇 |
1996年 | 2篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 7篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有2362条查询结果,搜索用时 15 毫秒
51.
The uterine acetylcholinesterase and total cholinesterase (acetylcholinesterase plus butyrylcholinesterase) activities in normal and fenchlorphos treated blue fox vixens were determined during various reproductive states.AChE and Total-ChE of non-medicated vixens in oestrus were about one half of those in anoestrus. In pregnant uteri (luteal phase) the activities were 25 % and 30% compared to anoestrus.In vixens given 100 mg/kg fenchlorphos for 3 weeks during anoestrus, the remaining activity of AChE in uterus were in average 37%. Pregnant and non-pregnant vixens in the luteal phase medicated prior to mating and during time of implantation, displayed AChE activities which were only moderabely reduced (remaining activities 83% and 72% compared to medicated animals in anoestrus: remaining activity 37%).Plasma ChE-activity increased during pregnancy in the controls while enzyme activity was strongly reduced in animals given 100 mg/kg fenchlorphos daily through the whole pregnancy.It was concluded that the previous reported embryotoxic effect of fenchlorphos in the blue fox did not seem to be directed towards the moderate inhibition of the uterine cholinesterases. 相似文献
52.
53.
In the present study, the effects of cefquinome, a 4th generation cephalosporin, on clinical, biochemical, haematological, and blood gas variables were investigated. Five healthy dogs were injected with cefquinome (1 mg/kg body weight, IM, daily) for 14 days. Negative effects of cefquinome on clinical, biochemical, and haematological variables were not observed, but it did change some blood gas variables. 相似文献
54.
退化梯度对克氏针茅种群遗传分化的影响 总被引:7,自引:1,他引:7
对重度退化、轻度退化和正常样地的克氏针茅种群进行RAPD研究。结果表明,3个种群扩增条带总数、多态位点比率、种群内稀有位点数、遗传多样性和基因多样性均是正常种群>轻度退化种群>重度退化种群。用Shannon指数估算3个种群的遗传多样性,其中72.39%的遗传变异存在于种群内,26.89%存在于种群间。重度退化与轻度退化种群,重度退化与正常种群间的遗传相似系数分别为0.8993和0.8159。在重度退化情况下克氏针茅种群遗传结构发生了一定的遗传分化。 相似文献
55.
鸡的大肠杆菌病是由大肠埃希氏菌引起各日龄鸡都可感染发病,有败血型、地方流行型、腹膜炎型、输卵管炎型、脐炎型以及大肠杆菌肉芽肿等多种病状,病情复杂,治疗困难。笔者在长期工作中大量接触到该类病例,用自家病鸡分离菌株作成灭活铝胶苗对鸡预防和治疗,取得了满意的效果。具体报告如下:1病情河北省某农牧集团,养鸡总数约20万只,包括祖代鸡、父母代鸡、种鸡、蛋鸡及育成鸡。一向坚持自繁自养,人工授精及乳头饮水方式,但自1995年第四季度始,总有鸡死亡(较自然死亡率高3倍~4倍,种蛋孵化率降低规卜a个曾以庆大霉素50x106kg饮水… 相似文献
56.
双烯雌酚是一种人工合成的雌激素,因其残留对人体有明显的毒害,故而其在相关动物性产品中的残留受到世界各国的共同关注。目前,双烯雌酚残留检测方法主为仪器分析法,但其繁琐的分析步骤不适合药物的及时监控,而免疫学分析方法以其耗费低、特异强、灵敏高等优点,可作为兽药残留的筛选方法,因而具有广阔的应用前景。 相似文献
57.
58.
59.
乙型脑炎病毒NS1基因重组伪狂犬病毒的构建 总被引:7,自引:0,他引:7
设计1对引物从含有乙型脑炎病毒NS1基因的质粒pNS1上亚克隆NS1基因,将NS1基因插入到中间转移载体pUSK中,获得重组中间转移质粒pUSK—NS1。将pUSK—NS1与伪狂犬病毒Ea株TK/gG/LacZ^ 突变株基因组共转染真核细胞IBRS-2,通过空斑纯化得到了乙型脑炎病毒NS1基因重组伪狂犬病毒株TK/gG^-/NS^ 1。经检测,重组病毒能表达具有生物活性的NS1蛋白。该重组病毒可作为猪乙型脑炎和伪狂犬病双价基因工程疫苗用毒株。 相似文献
60.
In this study, the histo-anatomy of the accessory reproductive glands of the Anatolian souslik (Spermophilus xanthoprymnus) is investigated, using 102 males of the vouchers which were captured from central Anatolia and eastern Mediterranean regions. Averages of measurements taken from each part of the accessory reproductive glands were as follows: length of vesicular gland [right: 3.96 (+/-0.48) mm; left: 3.70 (+/-0.55) mm]; prostate gland [length: 2.55 (+/-0.38) mm; width: 2.63 (+/-0.45) mm]; length of bulbourethral gland [right: 2.32 (+/-0.33) mm; left: 2.37 (+/-0.39) mm], and the length of the pars pelvina of the urethra was 12.31 (+/-0.76) mm. Histological sections showed that vesicular gland was composed of typically branched tubulo-alveolar glands. As the fibrous connective tissue that was found among alveoles in the prostate was dense and relatively common, only few tubulo-alveolar glands occurred. The bulbourethral gland (Cowper's gland) was a tubulo-alveolar gland with a large and serrated lumen and septa between the alveoles consisted of dense fibro-muscular fibres. 相似文献