全文获取类型
收费全文 | 561篇 |
免费 | 97篇 |
国内免费 | 16篇 |
专业分类
林业 | 11篇 |
农学 | 60篇 |
基础科学 | 5篇 |
143篇 | |
综合类 | 231篇 |
农作物 | 54篇 |
水产渔业 | 18篇 |
畜牧兽医 | 119篇 |
园艺 | 28篇 |
植物保护 | 5篇 |
出版年
2025年 | 2篇 |
2024年 | 3篇 |
2023年 | 8篇 |
2022年 | 6篇 |
2021年 | 14篇 |
2020年 | 7篇 |
2019年 | 11篇 |
2018年 | 13篇 |
2017年 | 14篇 |
2016年 | 24篇 |
2015年 | 20篇 |
2014年 | 24篇 |
2013年 | 36篇 |
2012年 | 43篇 |
2011年 | 40篇 |
2010年 | 34篇 |
2009年 | 35篇 |
2008年 | 41篇 |
2007年 | 47篇 |
2006年 | 25篇 |
2005年 | 28篇 |
2004年 | 13篇 |
2003年 | 19篇 |
2002年 | 12篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 14篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1996年 | 15篇 |
1995年 | 19篇 |
1994年 | 10篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 10篇 |
1990年 | 12篇 |
1989年 | 10篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有674条查询结果,搜索用时 0 毫秒
131.
Antonio H.H. Minervino Raimundo A. Barrêto Júnior Rodrigo N.F. Ferreira Frederico A.M.L. Rodrigues Selwyn A. Headley Clara S. Mori Enrico L. Ortolani 《Research in veterinary science》2009,87(3):473-478
The susceptibility of cattle and buffalos to chronic copper poisoning (CCP) was compared by using cattle (n = 10) and buffalo (n = 10) steers distributed into two copper supplemented (n = 6) and two control (n = 4) groups. Supplemented animals received 2 mg copper (Cu)/kg body weight daily for one week, with an additional 2 mg weekly until the end of the experiment (day 105). Three liver biopsies (day 0, 45, and 105) were obtained for mineral analyses; clinical examinations and blood samples were obtained every 15 days. Three supplemented cattle and two buffalos with typical manifestations of CCP died. There were no differences in the frequency of mortality between cattle and buffalos; hepatic copper concentration was higher in cattle than buffalos. These findings suggest that buffalos and cattle might be equally susceptible to CCP. However, buffalos accumulate less liver copper than cattle and have a lower threshold of hepatic Cu accumulation, which leads to clinical manifestation of CCP. 相似文献
132.
王宏 《农业装备与车辆工程》2007,(7):37-38
农用车紧固件市场需求量很大,钢铁基体的紧固件在潮湿环境中极易锈蚀,造成安全隐患。本文介绍了一种大幅度提高紧固件耐腐蚀性能的氯化钾酸性镀锌工艺,详细叙述了该工艺的配方、配制过程、工艺维护及废水处理。生产实践证明,该工艺操作简便,节能降耗,符合国家清洁生产要求,该工艺的正确实施可大大提高紧固件的耐蚀性能,从而提高其寿命和使用安全性。 相似文献
133.
研究了在阳离子表面活性剂(CTMAB)作用下的锌(Ⅱ)与邻硝基苯基荧光酮(0-NPF)的显色反应。实验证明,在pH为(8.80~9.56)的硼砂缓冲体系中,锌(Ⅱ)与邻硝基苯基荧光酮,在阳离子表面活性剂(CTMAB)存在下,生成红色配合物,其最大吸收波长为570nm,摩尔吸收系数为6.29×104,锌含量在0~12.0μg/25ml范围内符合比耳定律,配合物中锌与邻硝基苯基荧光酮的比值为1:2,用此方法测定了食品中的锌(Ⅱ),结果满意。 相似文献
134.
园艺植物锌素营养的研究 总被引:2,自引:0,他引:2
对国内外有关锌在园艺植物上的应用 ,植物体对锌的吸收 ,锌的生理功能 ,土壤和植物体内锌与其他元素间的关系和常见园艺植物矫治缺锌症方面的研究现状进行了综述。 相似文献
135.
《Journal of plant nutrition》2013,36(2):417-430
Abstract Wheat grown on cadmium (Cd)‐uncontaminated soils can still potentially translocate unacceptable levels of Cd to grain. The effect of zinc (Zn) and Cd levels on Cd uptake and translocation in “Grandin” hard red spring wheat (HRS‐wheat) (Triticum aestivum L.) was investigated using a double chelator‐buffered nutrient solution [EGTA used to buffer Cd, Zn, copper (Cu), manganese (Mn), and nickel (Ni); and Ferrozine (FZ) used to buffer Fe2+]. In the Zn level series of treatments, Cd2+ activity was held constant at 10?10.7 M, and the Zn2+ activity was varied from 10?7.6 to 10?5.2 M. As Zn2+ activity increased, the translocation of Cd to the shoots decreased. The shoot : root Cd concentration ratio decreased from 0.20 to 0.03 as pZn2+ went from 7.6 to 5.2, indicating that adequate to high levels of Zn are effective in reducing Cd translocation to the shoots of “Grandin” HRS‐wheat. In the Cd series, the Zn activity was at 10?6.6 M, while Cd activity was increased from 10?10.7 to 10?9.2 M. High levels of Cd did not significantly affect the uptake and translocation of Zn in the roots and shoots. While at pCd2+ of 9.2, the root and shoot Cd concentrations significantly increased, there was not a significant increase in the shoot : root Cd ratio. This would indicate that even at high Cd2+ activities, Zn is effective in regulating Cd uptake and translocation in “Grandin” HRS‐wheat. 相似文献
136.
The aim of this work was to test the hypothesis that a moderate zinc deficiency induces intestinal alterations in weaned piglets. A diet based on maize and soybean meal was formulated without supplemental zinc (33 ppm, zinc-deficient) or with added zinc (113 ppm, control). These diets were pair-fed for 18 or 27 d to intra-litter pairs of piglets weaned at 21 d of age. The feed intake and growth, plasma concentrations of zinc and alkaline phosphatase (ALP) activity, and morphometry, enzyme activities and the microflora of the mid-jejunum were investigated. Feed intake and growth were similar between diets and diarrhoea was not observed. By contrast, plasma zinc and ALP activity were much lower in zinc-deficient piglets at slaughter (P < 0.001). The weight of organs was unaffected, except colonic tissue that was lighter in piglets fed the zinc-deficient diet (P < 0.05). Neither villus-crypt intestinal architecture nor mucosal enzyme activities were altered. Jejunal counts of lactic acid bacteria and coliforms tended to be higher in the zinc-deficient pigs (P ≤ 0.10). In conclusion, feeding a diet moderately deficient in zinc for 18–27 d induced limited intestinal alterations in weaned pigs. 相似文献
137.
138.
139.
对宁乡县某猪场母猪群皮肤粗糙,结痂、繁殖率降低等进行了调查,发现该县猪肝中锌含量164.57±34.57ppm,低于全省均值;土壤中锌含量7.07±2.11ppm,铜含量4.27±0.47 ppm,均低于国内外背景值;混合料中锌含量(39.70±0.71 ppm)低于需要量;毛锌(99.43±14.30 ppm);低于背景值,治疗试验表明,补充硫酸锌15d后,母猪的皮肤红斑消退,粗皮及痂皮脱落。 相似文献
140.