全文获取类型
收费全文 | 1529篇 |
免费 | 96篇 |
国内免费 | 119篇 |
专业分类
林业 | 116篇 |
农学 | 104篇 |
基础科学 | 19篇 |
107篇 | |
综合类 | 726篇 |
农作物 | 143篇 |
水产渔业 | 100篇 |
畜牧兽医 | 292篇 |
园艺 | 53篇 |
植物保护 | 84篇 |
出版年
2024年 | 9篇 |
2023年 | 26篇 |
2022年 | 43篇 |
2021年 | 42篇 |
2020年 | 41篇 |
2019年 | 58篇 |
2018年 | 36篇 |
2017年 | 68篇 |
2016年 | 65篇 |
2015年 | 56篇 |
2014年 | 53篇 |
2013年 | 82篇 |
2012年 | 99篇 |
2011年 | 96篇 |
2010年 | 85篇 |
2009年 | 99篇 |
2008年 | 93篇 |
2007年 | 91篇 |
2006年 | 90篇 |
2005年 | 64篇 |
2004年 | 53篇 |
2003年 | 37篇 |
2002年 | 35篇 |
2001年 | 39篇 |
2000年 | 33篇 |
1999年 | 44篇 |
1998年 | 22篇 |
1997年 | 15篇 |
1996年 | 24篇 |
1995年 | 21篇 |
1994年 | 18篇 |
1993年 | 20篇 |
1992年 | 15篇 |
1991年 | 16篇 |
1990年 | 11篇 |
1989年 | 16篇 |
1988年 | 9篇 |
1987年 | 10篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1978年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有1744条查询结果,搜索用时 140 毫秒
811.
应用隶属函数法评价33个苎麻资源的营养品质 总被引:2,自引:0,他引:2
为筛选出适宜的饲用苎麻(Boehmeria nivea)品种,对国家苎麻种质资源圃中33个苎麻资源的主要营养成分进行了测定,并利用隶属函数法对其营养价值进行综合评价。结果表明,33个苎麻资源主要营养平均含量为粗蛋白17.70%、粗脂肪2.60%、粗纤维24.97%、粗灰分13.83%、磷0.35%、钙3.56%。根据隶属函数分析结果,将33个苎麻品种分为3级,第Ⅰ级为综合营养品质优质型5个苎麻品种,Ⅱ级为品质中等型25个品种,Ⅲ级为品质差型3个品种。研究结果表明采用隶属函数法综合评估苎麻的营养品质是可行的,可以较好地揭示其综合营养品质,为饲用苎麻品种选育提供参考。 相似文献
812.
Nahla A Abdel-Aziz Abdelfattah Z M Salem Mounir M El-Adawy Luis M Camacho Ahmed E Kholif Mona M Y Elghandour Borhami E Borhami 《中国农业科学(英文版)》2015,(3)
As a result of agriculture practices, mil ion tons of agriculture are produced as a secondary or by-products;however, with low nutritive values. Many methods are applied to improve the nutritive value ... 相似文献
813.
814.
Ricardo Bressani Jaime L. Sosa 《Plant foods for human nutrition (Dordrecht, Netherlands)》1990,40(3):207-214
A comparative study of roasting, cooking with and without calcium hydroxide and extrusion cooking on the protein quality of Canavalia was conducted. The results suggested both extrusion and pressure cooking with lime to be equally effective in improving the protein quality of Canavalia and superior to pressure cooking alone and roasting, the latter effective possibly in destroying the antiphysiological factors in Canavalia but possibly also damaging its protein quality.The individual effects of roasting, cooking with different levels of calcium hydroxide, and with water under pressure at different times on the protein quality of Canavalia were also studied. These indicated a beneficial effect of calcium hydroxide added at a level of 0.45% by weight of seed, for 30 minutes under pressure. Cooking in water under pressure for 30 minutes with and without lime added was slightly better than cooking for longer periods of time. Roasting was also effective in improving the quality of Canavalia particularly when the T was adjusted at 170°C, and roasting conducted for 15 minutes. A significant improvement in the protein quality of processed Canavalia was obtained by methionine supplementation. 相似文献
815.
J. Delisle B. Chamberland A. Roy 《Plant foods for human nutrition (Dordrecht, Netherlands)》1987,37(3):265-274
Acetylated, hydrolysed and unmodified rapeseed proteins were compared to casein for nutritive value as determined by net protein ratio (NPR) and nitrogen apparent digestibility coefficient (ADC). The NPR and nitrogen ADC values of rapeseed proteins did not change significantly (P<0.05) after hydrolysis but decreased significantly (P<0.05) after 30% and 70% acetylation. Acetylation (30%) followed by protein hydrolysis decreased significantly (P<0.05) the NPR value but increased significantly (P<0.05) the nitrogen digestibility compared to the control and unmodified rapeseed proteins. Casein gave the highest value (P<0.05) for NPR and nitrogen ADC. Modification of rapeseed proteins significantly (P<0.05) decreased the nutritive value, and the effect was more pronounced with increasing level of acetylation. 相似文献
816.
在冀西北地区,通过研究青贮玉米与扁豆不同混播种植密度(青贮玉米∶扁豆设密度比1∶1、2∶1、3∶1)对混播饲草生物产量和营养成分的影响,筛选出了适合该地区的较优混播栽培模式。结果表明:青贮玉米和扁豆混播比例2∶1为最佳模式,在该模式下饲草的产量和品质均可达到最佳水平,混播饲草产量最高,比对照增产11.6%,粗蛋白含量得到明显增加,高出2.49个百分点。青贮玉米与扁豆混播技术简单,收益明显,必定会成为青贮玉米种植的一种新模式,在该地区奶牛粗饲料品质改良中发挥重要作用,具有非常广阔的推广前景。 相似文献
817.
淹水胁迫对嫁接甜椒幼苗几种抗氧化酶活性和渗透调节物质的影响 总被引:1,自引:0,他引:1
研究了淹水胁迫对嫁接甜椒幼苗抗氧化酶活性和渗透调节物质含量的影响,结果表明:随着淹水胁迫时间延长,嫁接甜椒苗丙二醛(MDA)含量和O2-·生成速率增加,嫁接苗含量显著低于自根苗;超氧物歧化酶(SOD)、过氧化物酶(POD)、脯氨酸和可溶性糖含量均表现上升的趋势,以上指标嫁接苗均高于自根苗。由此可知,淹水胁迫下嫁接苗有较高的抗氧化酶活性和较低的氧化损伤,从而增强甜椒的耐淹水性。 相似文献
818.
不同灌溉方式对初烤烟叶内在品质的影响(英文) 总被引:1,自引:0,他引:1
[目的]研究不同灌溉方式对烤后烟叶化学成分、致香物质含量及感官评吸质量的影响。[方法]采用田间试验,设浇灌和喷灌2个处理。浇灌处理分别在团棵期(5月26日)、旺长期(6月18日)各人工根灌1次,灌水量1kg/(株·次);喷灌处理在团棵期(5月26日)进行人工根灌1次,灌水量1 L/株。[结果]与浇灌方式相比,喷灌处理极显著提高中上部位烟叶主要致香物质,中橘三(C3F)等级烟叶主要致香物质非挥发性有机酸、挥发性有机酸、石油醚提取物、新植二烯、中性致香物质总量分别增加24.4%、32.6%、20.7%、33.8%、26.3%,上橘二(B2F)等级烟叶主要致香物质非挥发性有机酸、挥发性有机酸、石油醚提取物、新植二烯、中性致香物质总量分别增加16.3%、6.0%、6.1%、10.8%、8.1%;极显著降低中上部位烟叶烟碱含量,提高烟气协调性、醇和性及持火力。[结论]烤烟生产中,微喷灌技术是一种改善烤后烟叶内在品质的重要途径,在季节性干旱频繁烟区,烟草微喷灌溉可有效解决烟叶成熟期气候干旱导致烟叶品质下降的问题。 相似文献
819.
820.
《Journal of Crop Improvement》2013,27(1-2):261-284
Abstract Legume forage quality research is now concerned not only with nutritive value of forage for ruminant animals, but the impact of these nutrients on environmental quality. If we are to move to a more sustainable agriculture worldwide, more legumes must be incorporated into animal production systems. The goal of forage legume breeders is to tailor legume nutritive value to the needs of the consuming animals. A generalized priority list for legume nutritive value research includes high fiber digestibility, low anti-quality compounds, appropriate condensed tannins, reduced nonprotein nitrogen, and high sulfur amino acids. Although breeders have regularly found a wide range in forage quality within a given legume species, very few varieties with proven forage quality advantages have been released. Yield and persistence issues have dominated forage legume breeding. Improvement in forage quality often is linked to a reduction in yield and/or persistence, and also frequently results in complex genotype X environment interactions. Transgenic technology has almost limitless potential for improving legume forage quality and environmental quality, but only if the public can be convinced that transgenics are an acceptable risk. Structural and functional roles of legume plant cell walls and their relationships to forage quality are poorly understood. Research on the basic processes of forage legume growth and the relationships between growth and forage composition should result in the development of more accurate simulation models, and transgenic technology can provide us with the tools to understand these basic processes. 相似文献