全文获取类型
收费全文 | 304篇 |
免费 | 19篇 |
国内免费 | 9篇 |
专业分类
林业 | 20篇 |
农学 | 24篇 |
基础科学 | 23篇 |
20篇 | |
综合类 | 170篇 |
农作物 | 7篇 |
水产渔业 | 2篇 |
畜牧兽医 | 15篇 |
园艺 | 40篇 |
植物保护 | 11篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 12篇 |
2021年 | 9篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 14篇 |
2014年 | 13篇 |
2013年 | 14篇 |
2012年 | 30篇 |
2011年 | 29篇 |
2010年 | 18篇 |
2009年 | 17篇 |
2008年 | 23篇 |
2007年 | 20篇 |
2006年 | 10篇 |
2005年 | 17篇 |
2004年 | 13篇 |
2003年 | 3篇 |
2002年 | 8篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 1篇 |
1996年 | 8篇 |
1995年 | 1篇 |
1993年 | 4篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有332条查询结果,搜索用时 15 毫秒
1.
2.
普陀水仙花大球栽培技术试验初报 总被引:4,自引:0,他引:4
对普陀水仙花采用优质种球繁育技术、湿生栽培技术、种球阉割技术、病害综合防治技术和氮、磷、钾合理配方施肥技术5项技术措施后,其病害减轻,分生球减少,主球的大球率从原来的30%以下提高到60%以上. 相似文献
3.
大型灯泡式贯流泵CFD计算 总被引:2,自引:0,他引:2
大型灯泡式贯流泵在国内的研究与运用远远滞后于水轮机,导致国内低扬程泵站的选型一直突破不了传统的结构模式。为了研究解决国内低扬程泵结构选型问题,结合南水北调东线工程的蔺家坝泵站大型灯泡贯流泵,对适用低扬程工况的大型灯泡式贯流泵结构形式、流道水力损失、压力分布、流速分布进行了流体数值计算,并与模型试验作了比较。结果表明,流体数值计算的结果与试验数据非常接近,这为今后国内低扬程泵站设计选型提供了参考。 相似文献
4.
建立了发电机定子三维温度场计算的数学模型,以水轮发电机的半齿、半槽为计算区域,用有限元方法对5500kW/6471kVA灯泡贯流式发电机定子的温度场进行了求解,得到了发电机定子的温度场、各部件温度最高点及分布。通过求解定子机座和定子轭部的体平均温度,为机组的设计提供参考。 相似文献
5.
通过对湿度查算表湿度、干球温度、干湿球温差数据间关系的分析研究,提出一种根据湿度基准值进行二次线性插值求得湿度测量值的计算方法。对计算准确度、测量范围与基准值设置的关系做了讨论,给出了计算方法的C语言程序。本方法简便、准确,如计算结果四舍五人保留整数,则与湿度查算表数值完全吻合。实验表明:应用此方法的实时测湿系统,其湿度测量精度主要取决于温度测量精度。 相似文献
6.
介绍了冷凉地区繁育的百合种球的采收和冷处理技术,包括采收时间和标准、挖球、冷库消毒及摆放等. 相似文献
7.
Environmental and genetic factors influence growth and bulb development of onions by affecting their physiology. Photoperiod plays critical a role in bulb development and determines the suitability of a cultivar for a particular region. Long days and high temperatures promote onion bulbing. Bulbing is regulated more by temperature than photoperiod, as determined by growing degree days. Far-red light promotes bulbing most effectively. High-temperature storage of sets (above 20–25°C) results in increased total bulb yields, while very high temperature (25.5–31°C) or temperature below 0°C depresses yield. Plant density has an impact on bulb size: the higher the plant density the smaller the bulb size. Onion is more sensitive to water stress during bulb formation and enlargement than during the vegetative stage. Nitrogen improves bulb development, but too much nitrogen promotes excessive vegetative growth and delays maturity. Growth hormones (gibberellins and ethrel) promote the growth and development of bulbs. Flowering and bulb formation in onion is regulated by different (Flowering Locus T) FT genes. Two antagonistic FT-like genes regulate bulb formation. AcFT1 promotes bulb formation, while AcFT4 prevents AcFT1 up-regulation and inhibits bulbing. There is a need to link our research with the genetics and physiology of onions, to enhance bulb yield. 相似文献
8.
We histologically examined lectin binding patterns in the olfactory bulb of mallard ducks (Anas platyrhynchos) using 21 biotinylated lectins. Positive staining for the N‐acetylglucosamine‐specific lectins (Bandeiraea simplicifolia II, Datura stramonium, Lycopersicon esculentum, Solanum tuberosum, Triticum vulgare), galactose or N‐acetylgalactosamine‐specific lectins (Artocarpus intergrifolia, Phaseolus vulgaris erythroagglutinin, Phaseolus vulgaris leucoagglutinin, Ricus communis) and the mannose‐specific lectins (Lens culinaris and Pisum sativum) was observed in the olfactory nerve and glomerular layers. Canavalia ensiformis staining showed a similar pattern to that obtained with the lectins and there was also faint staining in the mitral cells. Olfactory nerve axons terminate in the glomeruli, where they make excitatory synapses with the dendrites of mitral cells. This finding indicates that glycoconjugates that bind Canavalia ensiformis play an important role in formation of glomeruli. No positive staining for the other lectins was seen in the olfactory bulb. Based on these results, we conclude that cell surface sugar moieties of the olfactory bulb in mallard ducks express N‐acetylglucosamine and mannose residues rather than N‐acetylgalactosamine residues. The carbohydrate composition of mallard duck olfactory bulb differed from that of other vertebrates found in previous studies. 相似文献
9.
Jaap M. Van Tuyl 《Scientia Horticulturae》1985,25(2):177-187
The production of Lilium longiflorum bulbs in The Netherlands, with its cool climate, has been a problem because of unsatisfactory bulb growth and the risk of premature sprouting of the daughter bulbs (summer sprouting). To investigate the possibilities of breeding a type of L. longiflorum that can be grown under cool climatic conditions, a collection of 27 L. longiflorum cultivars from Japan, The Netherlands and the United States was tested, together with two Asiatic hybrids and a L. speciosum cultivar, under low phytotron temperatures (10, 14, 17°C) and in field experiments.‘Mount Everest’, ‘Saeki’, ‘Indian Summer’ and ‘White American’ were among the best L. longiflorum cultivars, with less than 20% summer sprouting and good bulb production. This was in contrast to ‘Hinomoto’, ‘Ace’ and some American introductions, which showed more than 60% summer sprouting and low bulb production. The lower the phytotron temperature, the more summer sprouting occurred. The differences observed between the cultivars in the field experiments were in agreement with those observed in the phytotron. The genetic variation proved large enough to start a breeding program for L. longiflorum adapted to cool climate conditions. 相似文献
10.