首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   349篇
  免费   24篇
  国内免费   3篇
林业   27篇
农学   33篇
基础科学   4篇
  67篇
综合类   41篇
农作物   28篇
水产渔业   41篇
畜牧兽医   107篇
园艺   12篇
植物保护   16篇
  2024年   1篇
  2022年   16篇
  2021年   8篇
  2020年   12篇
  2019年   9篇
  2018年   9篇
  2017年   16篇
  2016年   13篇
  2015年   16篇
  2014年   5篇
  2013年   21篇
  2012年   15篇
  2011年   23篇
  2010年   25篇
  2009年   26篇
  2008年   17篇
  2007年   16篇
  2006年   22篇
  2005年   15篇
  2004年   17篇
  2003年   16篇
  2002年   11篇
  2001年   8篇
  2000年   5篇
  1999年   4篇
  1998年   4篇
  1997年   7篇
  1996年   2篇
  1995年   1篇
  1993年   7篇
  1992年   4篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1983年   1篇
  1980年   1篇
排序方式: 共有376条查询结果,搜索用时 31 毫秒
131.
Buer  Ha  Rula  Sa  Wang  Zi Yuan  Fang  Shu  Bai  Yu´e 《Genetic Resources and Crop Evolution》2022,69(3):1057-1068
Genetic Resources and Crop Evolution - Population genetic diversity contributes to the protection and utilization of germplasm resources, especially via genetic breeding. In the present study,...  相似文献   
132.
Genetic Resources and Crop Evolution - Lactuca indica L. is an undomesticated medicinal crop in the Asteraceae family. The study was carried out to identify elite genotypes for lettuce cultivation...  相似文献   
133.
为了探讨黑河上游冰沟流域不同土壤有机碳分布特征与土壤特性的关系,为黑河上游冰沟流域水源涵养研究提供科学依据,采用野外采样,室内分析方法,研究了4种土壤有机碳分布特征及其与土壤特性的关系。结果表明:4种土壤有机碳含量和密度在整个土壤剖面上均表现为:森林灰褐土>高山灌丛草甸土>高山草甸土>山地栗钙土,且垂直分布均随土壤深度增加而减少,说明黑河上游冰沟流域的森林灰褐土比其它土壤更有利于土壤有机碳储存和积累。森林灰褐土0~10 cm土壤有机碳密度为4.54 kg·m-2,略高于我国森林土壤0~10 cm土壤平均碳密度(4.24 kg·m-2),说明黑河上游冰沟流域的森林灰褐土区雨量充沛,林下植被丰富,凋落物现存量充足。4种土壤0~10 cm土层有机碳含量是整个土壤剖面土壤有机碳含量的30.69%~37.99%,有机碳密度是整个土壤剖面有机碳密度的29.31%~36.77%,说明黑河上游冰沟流域土壤有机碳含量和有机碳密度在表层具有很强的表聚性,不合理的人为活动引发的水土流失极易造成土壤有机碳储量的减少,应增加黑河上游冰沟流域植被覆盖度,保护生态环境,减少水土流失。4种土壤有机碳、全氮、CEC、田间持水量、团聚体在整个土壤剖面上均随土层深度增加而降低,而土壤容重、pH值在整个土壤剖面上均随土层深度增加而增大。经回归统计分析,4种土壤有机碳含量与土壤田间持水量、团聚体、全氮、CEC之间呈显著的正相关关系,与土壤容重、pH之间呈显著的负相关关系。这种变化规律与多数学者研究结果基本一致。  相似文献   
134.

The occurrence of weeds in water rice was surveyed in the Red River Delta, Vietnam during spring and summer rice-growing seasons in 1995 and 1996. Sixty different weeds from 19 plant families were recorded. The most important plant families as weeds of rice were Poaceae and Cyperaceae. The most important weed however was Rotala indica (Willd.) Koehne (Lythraceae) followed by Echinochloa crus-galli (L.) Beauv. and Cyperus difformis L. A brief comparison of this rice weed flora and those of Australia and California was made.  相似文献   
135.
136.
Alzheimer’s disease (AD) is a degenerative brain disorder characterized by a progressive decline in memory and cognition, mostly affecting the elderly. Numerous functional bioactives have been reported in marine organisms, and anti-Alzheimer’s agents derived from marine resources have gained attention as a promising approach to treat AD pathogenesis. Marine sterols have been investigated for several health benefits, including anti-cancer, anti-obesity, anti-diabetes, anti-aging, and anti-Alzheimer’s activities, owing to their anti-inflammatory and antioxidant properties. Marine sterols interact with various proteins and enzymes participating via diverse cellular systems such as apoptosis, the antioxidant defense system, immune response, and cholesterol homeostasis. Here, we briefly overview the potential of marine sterols against the pathology of AD and provide an insight into their pharmacological mechanisms. We also highlight technological advances that may lead to the potential application of marine sterols in the prevention and therapy of AD.  相似文献   
137.
基于SI-Albedo特征空间的土壤盐渍化遥感监测指数研究   总被引:1,自引:0,他引:1  
土壤盐渍化通常出现在气候干旱、土壤蒸发强度大、地下水位高且含有较多可溶性盐类的地区。它是一定的气候、地形、水文地质等自然条件共同对水盐运动产生影响的结果[1],这是一个复杂的动力学过程。因而对土壤盐渍化的探测、动态监测和制图是一项较为困难的工作。遥感技术能大面积重复获取同一地区的信息,具有宏观、综合、动态、快速的特点,并在速度、精度和成本花费方面凸显出众多优势[2]。现阶段运用遥感手段提取土壤盐渍化信息主要有两个方面:一是对遥感图像做相应的处理,突出盐渍化信息,但此种方法需要大量的实验;二是引入土壤含盐量、地下水等辅助量,但是引入的辅助量会引起图像的破碎化,有时难以满足要求,分类精度受到一定程  相似文献   
138.
139.
Silkworms with conjugated linoleic acid (CLA) incorporated into their lipids (designated CLA silkworms) were produced to enhance the quality of silkworms having a synergistic effect with CLA functions by dietary synthetic CLA. Silkworm larvae were fed fresh mulberry leaves (control diet) until the third instar stage and were then subjected to various levels (0%, 0.1%, 1%, 5%, and 10%) of CLA-sprayed mulberry leaves (designated CLA diet) beginning on the first day of the fourth instar stage and continuing to the third day of the fifth instar stage. CLA contents in CLA silkworms increased proportionally with increasing CLA levels of CLA diets. CLA silkworms on a 1% CLA diet contained 2.2 g CLA/100 g lipid without body weight reduction, whereas CLA silkworms on a 10% CLA diet contained 14.8 g CLA/100 g lipid with a significant reduction of body weight, relative to the control silkworms. The CLA content in the lipids of CLA silkworms on a 10% CLA diet was significantly higher than that of CLA silkworms on a 5% CLA diet. A 0.1% CLA diet was not sufficient to accumulate CLA in the silkworms. Most of the CLA (approximately 99%) of silkworm lipids was present in triglyceride (TG) with a similar ratio of c9,t11 and t10,c12 CLA isomers. These results suggest that a 1% CLA diet was suitable for the production of CLA silkworms.  相似文献   
140.
鸡公山野生木本蔬菜资源调查   总被引:1,自引:0,他引:1  
木本蔬菜绿色食品,营养价值高,开发潜力大。于2008年对鸡公山野生木本蔬菜资源进行调查,结果表明鸡公山有野生木本蔬菜植物34科74种,并对其开发利用提出建议。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号