全文获取类型
收费全文 | 6086篇 |
免费 | 220篇 |
国内免费 | 162篇 |
专业分类
林业 | 733篇 |
农学 | 488篇 |
基础科学 | 113篇 |
453篇 | |
综合类 | 1833篇 |
农作物 | 437篇 |
水产渔业 | 184篇 |
畜牧兽医 | 815篇 |
园艺 | 1085篇 |
植物保护 | 327篇 |
出版年
2024年 | 51篇 |
2023年 | 234篇 |
2022年 | 286篇 |
2021年 | 200篇 |
2020年 | 262篇 |
2019年 | 278篇 |
2018年 | 215篇 |
2017年 | 224篇 |
2016年 | 162篇 |
2015年 | 217篇 |
2014年 | 227篇 |
2013年 | 303篇 |
2012年 | 285篇 |
2011年 | 247篇 |
2010年 | 189篇 |
2009年 | 386篇 |
2008年 | 151篇 |
2007年 | 125篇 |
2006年 | 117篇 |
2005年 | 107篇 |
2004年 | 283篇 |
2003年 | 113篇 |
2002年 | 184篇 |
2001年 | 137篇 |
2000年 | 187篇 |
1999年 | 86篇 |
1998年 | 69篇 |
1997年 | 82篇 |
1996年 | 224篇 |
1995年 | 141篇 |
1994年 | 129篇 |
1993年 | 94篇 |
1992年 | 89篇 |
1991年 | 55篇 |
1990年 | 57篇 |
1989年 | 31篇 |
1988年 | 48篇 |
1987年 | 14篇 |
1986年 | 19篇 |
1985年 | 23篇 |
1984年 | 18篇 |
1983年 | 22篇 |
1982年 | 16篇 |
1981年 | 18篇 |
1980年 | 16篇 |
1979年 | 30篇 |
1978年 | 15篇 |
1977年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有6468条查询结果,搜索用时 15 毫秒
1.
采用文献资料法对食用菌多糖抗运动疲劳的研究进展情况进行了研究。结果表明:食用菌多糖提取方法不同而食用菌多糖的提取率也不相同,超声波法+复合酶法及微波法提取食用菌多糖提取率较高,2种方法科学合理的结合提取食用菌多糖以及不同产地、品种和不同部位提取率是未来学者们需要研究的领域;目前,只是对极少部分食用菌多糖抗运动疲劳进行了研究,研究对象(动物)、模型、指标、评价单一而没有确定最佳剂量的时间而没确定的量。为此,提出了未来应加强和重视食用菌多糖抗疲劳运动多食用菌、多对象(尤其是人)、多模型、多指标、多评价、最佳剂量的研究以及量-效、构-效关系的研究建议。 相似文献
2.
《中国油料作物学报(英文)》2021,6(3):137-144
Microwave, as a new heat treatment technology, has the characteristics of uniform and fast heating speed. It is an energy-saving technology known for improving oilseed product quality. Its efficiency mainly depends on the roasting power and time. However, the production of high-quality peanut butter using short-time roasting conditions are limited. Herein, we determined an appropriate microwave roasting power and time for peanuts and evaluated its impacts on the quality of peanut butter. Different roasting powers (400 W, 800 W and 1200 W) and times (4, 4.5, 5, and 5.5 min) were preliminarily tested. Among them, 800 W at 5 min was the most suitable. The roasting efficiency was further evaluated using color, sensory, bioactive compounds, storage stability, and safety risk factors of peanut butter produced from four peanut cultivars (Silihong, Baisha-1016, Yuanza-9102, and Yuhua-9414). The pre-treated butter obtained from three cultivars (Silihong, Yuanza-9102, and Yuhua-9414) with moisture content between 5% and 7.2% had a similar sensory score (6–7) as the commercial on a 9-point hedonic scale compare to the other. The color of the pre-treated peanut butter varies statistically with the commercial but remained in the recommended range of Hunter L1 values of 51–52, respectively, for high initial moisture peanut cultivars. The total polyphenol (35.20-31.59 ± 0.59 μmol GAE/g) and tocopherol (19.05 ± 0.35 mg/100 g) content in the butter obtained from three cultivars (Yuahua-9102, Yuhua, and Baisha-1016) and Silihong respectively, were significantly (P < 0.05) higher than those in the commercial butter. The induction times of all pre-treated butter (19.80 ± 0.99–7.84 ± 0.07 h) were significantly (P < 0.05) longer during storage at accelerated temperature than commercial samples. In addition, no benzo[a]pyrene was found in the pre-treated samples. Collectively, the microwave pretreated peanut butter was superior to the commercial one. These findings provided data support and a reference basis to promote microwave use for peanut butter production. 相似文献
3.
4.
黑龙江垦区农村居民点与田块间适宜耕作半径及影响因素 总被引:2,自引:2,他引:0
为探明黑龙江垦区农村居民点的适宜耕作半径及主要影响因素,该文以黑龙江农垦总局建三江管理局所辖八五九农场为研究区,以农场内的农村居民点为研究对象,利用2010年国土资源第二次调查矢量数据库,通过空间分析和多元线性回归的方法,进行了定量化的研究。研究结果表明:研究区内各个管理区的适宜耕作半径均值是5 055 m,耕作半径的最大、最小值分别为7 438和3 265 m;平均耕作半径对应农机出行时间为20 min,摩托车出行时间为10 min;适宜耕作半径与水田种植比例、土地面积、聚居居民点与对应连队几何中心偏差距离均值的显著性检验F值远大于F0.01,三者对适宜耕作半径具有极显著的影响,三者的回归系数依次为-17.892、0.208、-0.147,即水田种植比例较高的区域,适宜耕作半径相对较小;土地面积较大的区域,适宜耕作半径相对较大;偏差距离均值较大的区域,适宜耕作半径相对较小。 相似文献
5.
6.
7.
Xing ZHOU Yan-hong LU Yu-lin LIAO Qi-dong ZHU Hui-dan CHENG Xin NIE Weidong CAO Jun NIE 《农业科学学报》2019,18(10):2381-2392
The double-rice cropping system is a very important intensive cropping system for food security in China. There have been few studies of the sustainability of yield and accumulation of soil organic carbon(SOC) in the double-rice cropping system following a partial substitution of chemical fertilizer by Chinese milk vetch(Mv). We conducted a 10-year(2008–2017) field experiment in Nan County, South-Central China, to examine the double-rice productivity and SOC accumulation in a paddy soil in response to different fertilization levels and Mv application(22.5 Mg ha~(–1)). Fertilizer and Mv were applied both individually and in combination(sole chemical fertilizers, Mv plus 100, 80, 60, 40, and 0% of the recommended dose of chemical fertilizers, labeled as F100, MF100, MF80, MF60, MF40, and MF0, respectively). It was found that the grain yields of double-rice crop in treatments receiving Mv were reduced when the dose of chemical fertilizer was reduced, while the change in SOC stock displayed a double peak curve. The MF100 produced the highest double-rice yield and SOC stock, with the value higher by 13.5 and 26.8% than that in the F100. However, the grain yields increased in the MF80(by 8.4% compared to the F100), while the SOC stock only increased by 8.4%. Analogous to the change of grain yield, the sustainable yield index(SYI) of double rice were improved significantly in the MF100 and MF80 compared to the F100, while there was a slight increase in the MF60 and MF40. After a certain amount of Mv input(22.5 Mg ha~(–1)), the carbon sequestration rate was affected by the nutrient input due to the stimulation of microbial biomass. Compared with the MF0, the MF100 and MF40 resulted in a dramatically higher carbon sequestration rate(with the value higher by 71.6 and 70.1%),whereas the MF80 induced a lower carbon sequestration rate with the value lower by 70.1% compared to the MF0. Based on the above results we suggested that Mv could partially replace chemical fertilizers(e.g., 40–60%) to improve or maintain the productivity and sustainability of the double-rice cropping system in South-Central China. 相似文献
8.
为研究不同品种余甘子果实维生素C含量差异和余甘子果实维生素C积累规律,本研究以6个品种余甘子果实为试材,比较不同时期余甘子果实维生素C含量的差异,描绘维生素C积累动态曲线。结果表明,余甘子果实维生素C含量丰富,适宜作为食品加工和保健品的开发利用;其中秋白品种维生素C含量最高,适宜作为加工和遗传育种的原材料;余甘子果实作为加工原材料适宜采收期为10月20日左右;维生素C 的积累分为快速积累阶段,缓慢积累阶段,下降阶段,稳定阶段4个阶段。 相似文献
9.
在黑龙江盘中自然保护区区位、用地和资源的现状分析基础上,对保护区进行类型划分,确定保护区主要保护对象和规划目标,划分出保护区的核心区、缓冲区、实验区三大功能区域的范围和面积,进而再对保护区的规划管理设施和规划管理措施进行总体探讨,从而保证黑龙江盘中自然保护区的可持续发展。 相似文献
10.
为了解决三水区雪梨瓜种植面积的不断扩大、复种指数不断提高,品质退化、产量降低、病虫害严重的现象越来越突出的问题,佛山市农业科学研究所申请并开展了"蔬菜嫁接栽培技术研究及示范推广"课题研究,从2013—2015年,摸索出了一套适合本地生产雪梨瓜嫁接苗的技术和方法,即通过选择砧木、选择播期、营养土配方、高效嫁接、苗期管理、成苗运输等措施,缓解了嫁接操作不规范、生产管理不统一、苗木质量差异大、产量品质不理想的难题,初步实现雪梨瓜嫁接苗的工厂化、规模化生产,为三水雪梨瓜种植业的可持续发展提供了有力保障。 相似文献