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   271篇
  免费   14篇
林业   14篇
农学   2篇
基础科学   1篇
  44篇
综合类   9篇
农作物   10篇
水产渔业   30篇
畜牧兽医   159篇
园艺   1篇
植物保护   15篇
  2023年   1篇
  2022年   6篇
  2021年   8篇
  2020年   5篇
  2019年   4篇
  2018年   3篇
  2017年   4篇
  2016年   5篇
  2015年   11篇
  2014年   8篇
  2013年   23篇
  2012年   8篇
  2011年   17篇
  2010年   8篇
  2009年   4篇
  2008年   14篇
  2007年   18篇
  2006年   15篇
  2005年   18篇
  2004年   14篇
  2003年   17篇
  2002年   15篇
  2001年   5篇
  2000年   9篇
  1999年   9篇
  1998年   2篇
  1997年   2篇
  1993年   1篇
  1992年   3篇
  1991年   4篇
  1989年   1篇
  1988年   1篇
  1986年   1篇
  1985年   2篇
  1983年   1篇
  1981年   1篇
  1975年   1篇
  1973年   5篇
  1972年   1篇
  1971年   3篇
  1970年   1篇
  1968年   3篇
  1967年   1篇
  1966年   2篇
排序方式: 共有285条查询结果,搜索用时 15 毫秒
1.
2.
Sweet peppers (cv. Tosajishi beauty) with leaf blight symptoms were observed in Kochi Prefecture, 2003. Initially, small spots formed on leaves, and later enlarged to brown to dark brown spots, and eventually blighted leaves fell. Several bacteria that caused the same symptoms were isolated and subsequently reisolated. These bacteria were identified as Pseudomonas cichorii on the basis of bacterial characteristics and the 16S rRNA gene sequence. This is the first report of bacterial leaf blight in the sweet pepper in the world.  相似文献   
3.
In 12th century, the Buddhist priest Eisai brought tea ( Camellia sinensis L.) seeds to Japan from China and now tea plants are cultivated all over Japan except in the Hokkaido and Tohoku districts. The quality (reflected in the price) of Japanese green tea is affected by the nitrogen content. Consequently in tea fields, for last three decades large amounts of fertilizer have been applied to produce high quality tea. As a result, problems such as acidification of soil have been caused. It is also known that the growth of tea plants is stimulated by the addition of aluminum (Al) under acidic conditions. In this keynote address, some problems caused by excess applications of fertilizer in tea fields and the growth characteristics of tea plants related to Al are presented.  相似文献   
4.
H. Morita 《Geoderma》1975,13(2):163-165
The p-hydroxypropiophenone ester of stearic acid has been isolated sedge peat. This appears to be the first report of the ester as a natural product.  相似文献   
5.
6.
7.
8.
9.
We examined an epileptic focus by electroencephalography (EEG) by using an international 10-20 electrode system in 11 Shetland sheep dogs affected with familial idiopathic epilepsy. We also performed an evaluation of the amino acids in the cerebrospinal fluid (CSF) and a pathologic examination of the brains of 8 dogs that died from status epilepticus. Continuous electroencephalography demonstrated that an epileptic focus was initially detected in the frontal lobe, particularly the internal area, and that paroxysmal foci developed diffusely in other lobes of affected dogs with recurrent convulsions. The EEG analyses indicated spike and sharp wave complexes, which were considered to be paroxysmal discharges. An increased value for glutamate or aspartate was found in the CSF of some epileptic dogs. Histologically, acute neuronal necrosis and astrocytosis were distributed predominantly in the cingulate cortex and internal area of frontal cortex, less frequently in other areas of the cerebrum. The results of this study suggest that, initially, the dogs have an epileptic focus in the frontal lobe, and that the focus extends gradually to other areas of the cerebrum. Based on the distribution of neuronal necrosis and astrocytosis, acute neuronal damage may be related to the superexcitation of neurons following epilepsy.  相似文献   
10.
We performed a pathologic examination of the brains of three dogs in an epileptic beagle colony. Histologically, all the cases had diffuse astrocytosis in the cerebral cortex and basal ganglia as well as the hippocampus, whereas they showed acute nerve cell change in the hippocampus and some other areas of the cerebrum. One of these animals showed laminar myelin pallor associated with the presence of many vacuoles in the IV to VI layers of the bilateral motor cortices. Most of the vacuoles contained fine granules stained with luxol-fast-blue stain. Ultrastructural examination revealed that some oligodendrocytes and perineuronal satellite oligodendrocytes in the bilateral cerebral motor cortices of the two affected dogs had many vacuoles surrounded by myelin-like lamellar structures. These findings suggest a possibility that astrocytosis in the cerebrum and vacuolar degeneration of oligodendrocytes in the cerebral motor cortex may be, at least in part, related to the occurrence or development of seizures.  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