全文获取类型
收费全文 | 179篇 |
免费 | 9篇 |
国内免费 | 24篇 |
专业分类
林业 | 1篇 |
农学 | 13篇 |
基础科学 | 34篇 |
40篇 | |
综合类 | 60篇 |
农作物 | 8篇 |
水产渔业 | 5篇 |
畜牧兽医 | 27篇 |
园艺 | 6篇 |
植物保护 | 18篇 |
出版年
2024年 | 2篇 |
2023年 | 2篇 |
2022年 | 7篇 |
2021年 | 9篇 |
2020年 | 8篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 14篇 |
2016年 | 11篇 |
2015年 | 8篇 |
2014年 | 8篇 |
2013年 | 11篇 |
2012年 | 13篇 |
2011年 | 15篇 |
2010年 | 7篇 |
2009年 | 9篇 |
2008年 | 10篇 |
2007年 | 8篇 |
2006年 | 16篇 |
2005年 | 8篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 1篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有212条查询结果,搜索用时 15 毫秒
1.
《The Journal of Applied Poultry Research》2007,16(3):351-360
Poultry litter contains many trace elements such as As, Cu, and Zn, and its land application may lead to the accumulation of these elements in soils, especially near the soil surface. The objectives of this study were to determine the total amount of trace elements and evaluate the effect of litter granulation and various litter to water extraction ratios on water extractable trace elements in 8 raw and granulated litter products. Granulated litters that contained urea, dicyandiamide, or hydrolyzed feathermeal had significantly lower contents of total As, B, Cu, Mn, and Zn than untreated litters because of the dilution of litters with additives. Trace element concentrations (mg/L) in the water extracts of the various poultry litters generally decreased when extraction ratios (litter to water) shifted from 1:10 to 1:250, or as the amount of poultry litter decreased with a constant water volume (200 mL). But, the water extractable content of trace metals (mg/kg) generally increased from an extraction ratio of 1:10 to 1:200, with values similar at 1:200 and 1:250 extraction ratios. Based on our results, we suggest using a 1:200 extraction ratio when evaluating water extractable As, Cu, and Zn in poultry litters. The estimated land application rates of trace metals, when poultry litter is applied on the basis of total P content, were considerably lower than the trace metal loadings allowable under the current environmental regulations governing biosolids and other materials with measurable amounts of trace metals. The laboratory water extractions of poultry litters and granulated products have increased our understanding of the potential risks to water quality posed by the land application of poultry litter and will contribute to the development of base knowledge needed to define land application practices that are protective of soil and water quality. 相似文献
2.
3.
ABSTRACTAims: To evaluate the outcome of surgical management of entropion of the upper and lower eyelids in Shar Pei dogs which had previously undergone temporary palpebral tacking, using the Stades forced granulation procedure of the upper eyelid only.Methods: Medical records were retrospectively searched to identify Shar Pei dogs referred for bilateral entropion of both the lower and upper eyelids, and that were treated with the forced granulation procedure of the upper eyelid only. Dogs were included if they had previously undergone unsuccessful temporary palpebral tacking and had at least three follow-up examinations in the 30 days following surgery.Results: Twenty-seven Shar Pei dogs with a median age of 7.9 (min 4, max 24) months were included in the study. Before surgery, all dogs showed signs of severe ocular discomfort with bilateral keratitis and visual deficit due to blepharospasm, enophthalmos and protrusion of the third eyelid. In 13/54 eyes, keratitis was associated with a corneal ulcer. When re-examined 4 weeks after surgery, correction of the upper eyelid entropion and associated trichiasis resolved ocular signs in 50/54 eyes. Mild bilateral lower entropion remained in two dogs postoperatively, which underwent revision surgery with the Hotz-Celsus technique. There were no cases of long-term recurrence of entropion or ocular irritation in the 38 eyes (19 dogs) which were re-examined 1 year after surgery.Conclusion and clinical relevance: The forced granulation procedure performed on the upper eyelid only was effective for correction of entropion in the Shar Pei dogs included in this study. In our experience, it is preferable to operate on the upper eyelid alone, rather than attempting to correct upper and lower entropion during the same surgical operation. The dog can then be reassessed a few weeks later to determine whether the lower entropion is anatomical or secondary to the severe blepharospasm resulting from the painful ocular irritation. 相似文献
4.
摘 要:柑橘砂囊粒化是柑果成熟期与采后贮藏期的常见生理性病害,严重影响果实品质。本文采用1.5 T 高场磁共振成像仪对采后贮藏30 d的琯溪蜜柚[Citrus grandis (L.) Osbeck]果实进行磁共振扫描检查,并以同层断面解剖图为对照,评估磁共振成像(MRI)应用于柑橘砂囊粒化症无损检测的有效性。结果表明, MRI检测中,T2WI能够显著区分果肉组织与海绵层组织的信号差异,其信号强度可代表果实组织相对含水量;T2WI信号在砂囊粒化部位强度显著降低,病变组织的失水特征清晰,与解剖结果一致。T2WI对砂囊粒化的确诊率100%,显著优于T1WI成像的识别率41.7%(χ2 = 5.76,P = 0.016);T2WI和T1WI均能显示种籽照影,但T2WI对果肉组织影像的分辨率优于T1WI,因此MRI的T2WI分析可作为一种无损检测方法,对柚商品果实上市前砂囊粒化症发生程度以及种籽有无进行评估。 相似文献
5.
为了提高鮑资源的利用率,开发新型香精,以鲍蒸煮液美拉德反应产物为基料,感官评定为指标,在单因素及L_9(3~4)正交试验基础上,确立了口感和海鲜风味俱佳的鲍复合调味品最佳配方为:盐添加量35%、味精添加量40%、玉米淀粉添加量9%、鲍风味基料添加量为6%、白砂糖添加量4%、麦芽糊精添加量3%、呈味核苷酸二钠(I+G)添加量1.5%、酵母抽提物添加量1.5%。研究了不同的造粒方式和干燥方法对颗粒产品吸湿性、溶解性、流动性、质构特性及感官评定的影响;相关理化、性能指标为:完全溶解于90~100℃热水中的时间需要72 s,且分散良好、溶液微浑浊、无沉淀,鲜味足;堆密度为(0.61±0.01)g/cm~3,硬度为(3 642±122.198)g,吸湿性为(9.35±0.01)%,临界湿度值为60%,休止角为33.0°,总体可接受度为(7.81±0.12)分。研究结果表明,旋转造粒和流化床干燥的产品质量最佳,吸湿性比较小,溶解性、流动性和质地性都比较好,感官评分最高。 相似文献
6.
CHRISTINE A. COCHRANE 《Veterinary dermatology》1997,8(4):259-272
Abstract Wound models attempt to simulate the natural healing processes in wounds. However, all models have significant limitations due to the complexity of the tissue repair process. Much can be learned from wound models in vitro by the use of cell culture techniques. The horse can provide a suitable naturally occurring model of chronic wound healing because it has many similarities to wound healing encountered in human medicine. The tissue architecture was investigated with regard to extracellular matrix and growth factor distribution during wound healing and growth factors were consistently present in the wound area. Biochemical investigations revealed increased levels of hydroxyproline, collagen, and TGFβ1 in exuberant granulation tissue. Equine wound models were established in vitro using cell culture techniques and growth factors had significant effects on the growth of the cells and their ability to synthesize collagen. Two gelatinases (MMP-2 and MMP-9) were detected in the tissues and wound fluid samples investigated. Zusammenfassung Wundmodelle haben zum Ziel, die natürlichen Heilungsprozesse in Wunden zu simulieren. Allen Modellen sind durch den komplexen Gewebsheilungsprozess deutliche Grenzen gesetzt. Durch die Verwendung von Zellkulturtechniken kann von Wundmodellen in vitro viel abgeleitet werden. Das Pferd stellt wegen der vielen Ähnlichkeiten zur humanmedizinischen Wundheilung ein geeignetes Modell für chronische Wundheilung dar. Die Gewebsarchitektur wurde bezüglich der Verteilung von extrazellulärer Matrix und von Wachtumsfaktoren während der Wundheilung untersucht; Wachtsumsfaktoren waren ständig in der Wunde vorhanden. Biochemische Untersuchungen ergaben erhöhte Hydroxyprolin-, Kollagenund TGFβ1-Spiegel. Wundmodelle beim Pferd in vitro und Zellkulturtechniken wurden entwickelt; Wachstumsfaktoren hatten deutliche Wirkung auf die Zellen und ihre Fahigkeit zur Kollagensynthese. Zwei Gelatinasen (MMP-2 und MMP-9) wurden im Gewebe identifiziert und Wundflüssigkeitsproben untersucht. [Cochrane, C.A. Models in vivo of wound healing in the horse and the role of growth factors. (Wundheilungsmodelle in vivo beim Pferd und die Rolle von Wachstunisfaktoren). Veterinary Dermatology 1997; 8 : 259–272] Resumen Los modelos de heridas intentan estimular el proceso natural de curación de heridas. Sin embargo, todos 10s modelos presentan limitaciones considerables debido a la complejidad del proceso de curación de heridas. Se puede aprender mucho de modelos de heridas in vitro mediante el uso de técnicas de cultivo celular. El caballo puede suponer un modelo natural adecuado de curación crónica de heridas ya que se asemeja a la curación de heridas en medicina humana. Se investigó la arquitectura tisular en referencia a la matriz extracelular y la distribución de factores de crecimento viendo que los factores de crecimiento se encontraban presentes de forma constante en el área de la herida. Las investigaciones bioquímicas revelaron incremento en los niveles de hidroxiprolina, colágeno y TGFbl en tejido de granulación exhuberante. Se establecieron modelos in vitro de heridas equinas utilizando técnicas de cultivo celular y los factores de crecimiento tuvieron efectos significativos en el crecimiento de las células y su capacidad de sintetizar colágeno. Se detectaron dos gelatinasas (MMP-2 y MMP-9) en 10s tejidos y muestras de fluidos de las heridas investigadas. [Cochrane, C.A. Models in vivo of wound healing in the horse and the role of growth factors. (Modelos de curacion de heridas in vivo en el caballo y el papel de 10s factores de crecimiento). Veterinary Dermatology 1997; 8 : 259–272] Résumé Les modèles de plaies tentent de simuler les processus naturels de cicatrisation. Cependant tous les modèles ont des limitations significatives dues à la complexité des processus de réparation des tissus. Beaucoup peut être étudié sur des modèles de plaies in vitro suite à l'utilisation des techniques de culture cellulaire. Le cheval peut constituer un modèle nature1 fiable de cicatrisation chronique de plaie de par les nombreuses similarités qu'il partage avec la cicatrisation des plaies en médecine humaine. L'architecture tissulaire a étéétudiée concernant la matrice extracellulaire et la distribution des facteurs de croissance pendant la cicatrisation, et les facteurs de croissance se sont montrés présents de façon consistante dans la zone de la plaie. Des investigations biochimiques ont révélé une élévation des taux d'hydroxyproline, collagène, et TGFβ1 dans la granulation tissulaire exubérante. Des modèles équins de plaies ont étéétablis in vivo en utilisant des techniques de culture cellulaire et les facteurs de croissance ont montré des effets significatifs sur la croissance des cellules et leur capacité de synthétiser le collagène. Deux gélatinases (MMP-2 et MMP-9) ont été détectées dans les tissus et les échantillons de fluide des plaies ont été analysés. [Cochrane, C.A. Models in vivo of wound healing in the horse and the role of growth factors. (Modeles in vivo de cicatrisation des plaies chez le cheval et role des facteurs de croissance). Veterinary Dermatology 1997; 8 : 259–272] 相似文献
7.
8.
根据植物的蒸腾机理与土壤的蒸发机制,利用生物膜技术,研制了参考蒸发蒸腾仪。该仪器可很好地模拟土壤蒸发与植物蒸腾的自然物理过程。从理论上对仪器直接测定法与Penman-Monteith法、蒸发皿法进行了对比分析。在应用试验上,利用蒸渗仪值对三种方法进行了校核,结果表明:仪器直接测定法的精度稍差于Penman-Monteith法,但较蒸发皿法有很大提高。仪器使用方便、维护简单、价格低廉,易为我国普遍存在的经济与文化水平不高的农民用户所接受,将有良好的商品化开发及广阔的市场应用前景。 相似文献
9.
Depending on the top and subsoil textures, semi-arid soils exhibit cohesive and frictional properties that are associated with the relatively high soil strength, bulk density and penetration resistance. The objective of this study was to gain the knowledge of mechanical properties of the compacting chromic luvisols in order to improve the design of tillage tools. Therefore, we applied critical state soil mechanics to study the stress–strain behaviour of the luvisols using triaxial tests under laboratory conditions. Field investigations involved random collection of undisturbed soil samples which were subjected to triaxial testing first by isotropic consolidation and compression and then triaxial shearing. Plots of deviatoric stress against axial strain were made to determine the soil shear strengths at the critical states over different soil water levels and the two soil depths of 0–20 cm for the plough and 20–40 cm for the hard pan layers, respectively. An exponential model used to fit the deviatoric stress–axial strain test data accurately predicted the trends. Soil water significantly influenced the shear strength, cohesion (c′) and internal angle of friction (′) and hence the mechanical behaviour of the luvisols. The regression equations developed showed that c′ and ′ have quadratic relationships with soil water. The very high clay bonding strength in the subsoil (hard pan) layer resulted in high shear strength, bulk density and penetration resistance values for this soil layer. The increase in shear strength with decreasing water content affected the deviatoric stress–axial strain relationships between the upper and lower plastic limits of the sandy soil. Thus, as the soil dried, the soil ceased to behave in the plastic (ductile flow) manner and thus began to break apart and crumble. The crumbling was indicative of brittle failure. The transition stage from an increase to a decrease in c′ and ′ values with soil water occurred in the soil water content range of 6–10%. Knowledge of stress–strain behaviour of compacting soils is of practical significance in the design of appropriate tillage tools for the specific soil type. 相似文献
10.
明确作物各生育期水分需求,并制定合理灌水制度是节水增产的重要途径。本文以华北地区日光温室番茄为研究对象,设置3种水面蒸发系数,分别在开花坐果期轻度(k_(0.7)k_(0.9))或中度(k_(0.5)k_(0.9))水分亏缺,成熟采摘期轻度(k_(0.9)k_(0.7))或中度(k_(0.9)k_(0.5))调亏控水,以充分灌水(k_(0.9)k_(0.9))为对照,对番茄生长发育及其产量和品质进行了分析。结果显示:k_(0.7)k_(0.9)和k_(0.5)k_(0.9)植株生长速率分别较k_(0.9)k_(0.7)和k_(0.9)k_(0.5)弱,开花坐果期水分亏缺会导致产量降低1.2%,WUE降低11.2%;对比各个处理,k_(0.9)k_(0.9)产量最高,为141.07t/hm~2,但WUE偏低,仅为47.99kg/m~3,与产量相差不大的k_(0.9)k_(0.7)相比,k_(0.9)k_(0.9)灌水量增加29mm,WUE却降低6.8%。品质方面,除果实硬度外,番茄在成熟采摘期亏水50%可显著提高果实营养品质。最后,提出适合华北地区温室滴灌番茄的经济耗水指标,即全生育期灌水量约为230mm时可达到节水高产和高效的统一。 相似文献