全文获取类型
收费全文 | 2270篇 |
免费 | 85篇 |
国内免费 | 72篇 |
专业分类
林业 | 311篇 |
农学 | 244篇 |
基础科学 | 26篇 |
139篇 | |
综合类 | 972篇 |
农作物 | 82篇 |
水产渔业 | 9篇 |
畜牧兽医 | 183篇 |
园艺 | 398篇 |
植物保护 | 63篇 |
出版年
2023年 | 30篇 |
2022年 | 97篇 |
2021年 | 170篇 |
2020年 | 152篇 |
2019年 | 143篇 |
2018年 | 48篇 |
2017年 | 74篇 |
2016年 | 154篇 |
2015年 | 150篇 |
2014年 | 153篇 |
2013年 | 131篇 |
2012年 | 553篇 |
2011年 | 131篇 |
2010年 | 106篇 |
2009年 | 54篇 |
2008年 | 28篇 |
2007年 | 41篇 |
2006年 | 29篇 |
2005年 | 32篇 |
2004年 | 24篇 |
2003年 | 9篇 |
2002年 | 6篇 |
2001年 | 14篇 |
2000年 | 14篇 |
1999年 | 14篇 |
1998年 | 10篇 |
1997年 | 9篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 11篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 2篇 |
排序方式: 共有2427条查询结果,搜索用时 15 毫秒
31.
Cui Xudong Su Xiaohua Zhang Bingyu Chu Yanguang Huang Qinjun Zhang Weixi Liu Boyang 《中国林业科技(英文版)》2012,(3):54-55
Compared with the species of Leuce section,the difficulty in plant regeneration during tissue culture for the species of Aigeiros section is a key limiting factor for their application in genetic engineering of forest trees.In this study,the plant growth regulators combination,copper concentration,light intensity,and the selection pressures of kanamycin were investigated using leaves of Populus×euramericana cl.’Bofeng’ as explants,and a stable and high efficient regeneration system was established.Using this system,both the shoot regeneration rate and rooting rate were up to 100%,and the average number of differentiated shoots in each leaf explant was up to 20,and the survival rate of seedlings reached 98%.The optimal selection pressure of kanamycin in shoot inducement for leaf-explant was 40 mg·L-1,and the optimal selection pressure of kanamycin in root inducement of adventitious bud was 20 mg·L-1.The authors also found that differentiation rate of adventitious buds of P.×euramericana cl.’Bofeng’ could be significantly promoted by increased copper concentration,and this is the first report about the key role of copper(Cu) in explant regeneration of Poplars.This regeneration system with high frequency which was established by the authors was as good as that of species of Leuce section,and it provides a good technological platform for genetic engineering of forest tree which uses the species of Aigeiros section as model materials. 相似文献
32.
农民工随迁子女教育问题是当前一个亟待解决的社会难题。由于国家实施"两为主"政策,致使流入地政府承受着巨大的财政压力,在解决农民工随迁子女教育问题上心有余而力不足。而近年来引进的"教育券"制度,在实际工作中也存在一定的局限性。基于由国家、流出地政府、流入地政府按一定比例共同承担农民工随迁子女义务教育经费的理论,提出的"教育卡"新构想,则可以从操作层面较好地解决教育经费承担的一系列问题。 相似文献
33.
云南省保山市2006年2月引进甜柿品种大秋和阳丰接穗,在当地进行高接试种。经初步观察,大秋表现早丰产、果大、果面无纵沟,品质极上等,明显优于当地主栽品种次郎;阳丰表现生长健壮、早丰产、果面纵沟不明显,果实商品外观优于次郎,但果肉品质与次郎大致等同。 相似文献
34.
胡红晓 《农业图书情报学刊》2010,22(8):260-262,290
通过对某专业院校图书馆文献借阅情况调查,就改进院校图书馆管理,优化读者服务谈了一些看法。侧重于研究教学型的专业院校图书馆作讨论。 相似文献
35.
柿子发酵酒酯的生成规律初探 总被引:3,自引:0,他引:3
分析了不同柿子发酵酒样品中的主要有机酸和主要酯香成分,结果表明,柿子发酵酒中主要有机酸有酒石酸和乳酸,主要挥发酯是乳酸乙酯和乙酸乙酯。自然老熟的柿酒中乳酸乙酯含量高于乙酸乙酯,采用冷热处理方法老熟的柿酒中乙酸乙酯的含量高于乳酸乙酯。 相似文献
36.
M. Scortichini D. D'Ascenzo Daniela Di Silvestro 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(6):625-627
In spring 1996, extensive leaf necrosis and twig dieback were observed on young sweet persimmon (Dyospiros kaki L.) trees, cultivars O'Gosho, Hachija, Mercatelli and Kaki-tipo planted in the Abruzzo region (central Italy). Many trees were killed. When the dieback reached the trunk, in many cases, new vegetation was noticed above the graft point. The cultivar Jiro-C was not affected by the disease. During 1997, no symptoms were observed on any plant. The orchard was planted in a clay soil with a very low content of organic matter. Biochemical, nutritional and pathogenicity tests indicated Pseudomonas syringae pv. syringae van Hall as the causal agent of the disease. This is the first report of this bacterium as a pathogen of sweet persimmon in Europe. 相似文献
37.
从农民土地利用偏好以及居民地域性认同出发,将农民土地利用偏好分为农业生产功能偏好和经济生产功能偏好2类;并运用数学方法求取居民地域性认同综合指数,建立Logistic二项回归模型,研究农民土地利用偏好和居民地域性认同的相关性。结果表明,地域性认同程度高的农民更偏好于土地的经济生产功能。地方在开展土地整理或制定土地利用计划时,可根据当地居民地域性认同程度选择增大农地面积或是商铺、工厂的面积,提高人民的满意度。 相似文献
38.
39.
以浙江省诸暨市为例,对林改背景下林业经营方式转型升级进行了探讨,从整体看,初步形成了"政府搭台+龙头企业带动+合作社互助+林农家庭参与"的林业生产发展方式;从个体看,林农创业也逐步从传统的家庭型创业转向多种形式的现代经营方式创业。经营方式的转型升级为林农创业致富起到了积极的推动作用。 相似文献
40.
《Plant Production Science》2013,16(2):185-192
AbstractRice productivity is related to the ability of plants to adapt to heat stress. The heat-tolerant cultivars ‘Nikomaru’ and ‘Chikushi 64’ and heat-sensitive cultivar ‘Hinohikari’ were grown at 30ºC and 25ºC for 49 days after flowering. At 30ºC, only a few white immature kernels were produced in ‘Nikomaru’ and ‘Chikushi 64’, but about 22% of grains had immature kernels in ‘Hinohikari’. The high temperature(30ºC) caused no significant changes in grain dry weight, water content, and the NMR T1 value during the early ripening stage in ‘Nikomaru’ and ‘Chikushi 64’. It also did not affect grain development, especially with respect to the nucellar epidermis, in ‘Nikomaru’ and ‘Chikushi 64’, but caused clear cessation of development of the nucellar epidermis at 14 days after flowering in ‘Hinohikari’. In addition, high temperature decreased the amylose content and increased hardnessvs. adhesion ratio of cooked rice in both ‘Nikomaru’ and ‘Chikushi 64’ resulting a softer, less sticky texture, but not in ‘Hinohikari’. The maximum viscosity and breakdown values were increased, and final viscosity decreased at 30ºC in all three cultivars. These results suggested that starch in the endosperm of grains changed from a fluid state to a doughy state more slowly in ‘Nikomaru’ and ‘Chikushi 64’ than in ‘Hinohikari’, in which the water content and NMR relaxation time decreased, and transported assimilates accumulated slowly during grain development. 相似文献