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   895篇
  免费   70篇
林业   52篇
农学   13篇
基础科学   1篇
  132篇
综合类   98篇
农作物   47篇
水产渔业   53篇
畜牧兽医   478篇
园艺   18篇
植物保护   73篇
  2024年   2篇
  2023年   13篇
  2022年   14篇
  2021年   33篇
  2020年   37篇
  2019年   43篇
  2018年   30篇
  2017年   29篇
  2016年   33篇
  2015年   18篇
  2014年   35篇
  2013年   47篇
  2012年   57篇
  2011年   65篇
  2010年   33篇
  2009年   40篇
  2008年   66篇
  2007年   59篇
  2006年   52篇
  2005年   50篇
  2004年   38篇
  2003年   34篇
  2002年   26篇
  2001年   11篇
  2000年   8篇
  1999年   4篇
  1998年   3篇
  1997年   3篇
  1996年   3篇
  1993年   2篇
  1992年   2篇
  1991年   2篇
  1989年   2篇
  1986年   8篇
  1985年   8篇
  1984年   3篇
  1983年   13篇
  1982年   5篇
  1981年   2篇
  1980年   2篇
  1979年   5篇
  1978年   4篇
  1974年   2篇
  1963年   2篇
  1956年   1篇
  1948年   1篇
  1947年   2篇
  1946年   1篇
  1944年   1篇
  1940年   1篇
排序方式: 共有965条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Briefly noted is Rep. Albert Gore's introduction of legislation to create a commission to review developments in genetic engineering with potential human application. The proposed commission would consider medical, legal, ethical, and social implications of this research. It would be a purely advisory commission composed of six scientists; six experts in law, theology, ethics, or the social sciences; and three laymen.  相似文献   
5.
An outbreak of perinatal foal mortality associated with a herpesvirus is described. Twenty two foals either were still-born, or died soon after birth, or were weak and soon developed severe respiratory signs, or were normal at birth and developed respiratory symptoms 18 to 24 hours later. Elevated temperatures, heart and respiratory rates were constant features. The animals were severely leucopaenic, and showed an absolute neutropaenia. At autopsy the lungs were enlarged, and showed varying degrees of aeration and moderate to severe oedema and congestion. Histopathology showed an acute focal necrotising bronchiolitis with the presence of intranuclear eosinophilic inclusion bodies. Herpesvirus was recovered from 9 foals in cell culture and identified by electron microscopy.  相似文献   
6.
1. The electrophoretic patterns of water‐soluble proteins of avian muscle showed differences due both to species and to muscle type.

2. Each muscle pattern within a species showed a unique protein band which distinguished that species from other species.  相似文献   

7.
8.
Wakame, Undaria pinnatifida, is one of the most popular seaweeds used for human consumption in the world. Wakame quality is mainly valued on the basis of its morphological features. Continual inbreeding and directional selection have traditionally been used with economic seaweeds to obtain elite strains with high‐quality forms. In this study, we compared the morphological traits of cultured sporophytes originating from wild and selected strains of U. pinnatifida in Galicia (NW Spain). Seedlings (young sporophytes) of the two strains were cultured at a sheltered site in a coastal bay of Galicia under the same environmental conditions. Sixteen different morphological measurements were taken on cultured sporophytes. We found that the sporophytes of both wild and selected strains were significantly similar in all studied morphological characters. These results suggest that the morphology of cultured strains of U. pinnatifida from Galicia is due to environmental conditions and that specific morphological traits are dependent on the cultivation environment. Consequently, the morphological traits of Galician U. pinnatifida populations are not an important factor in selective breeding for enhanced wakame quality, and hence, for the establishment of a germplasm bank (e.g., gametophyte stocks).  相似文献   
9.
This study evaluated the influence of calcium and magnesium ions on the empirical rheological properties of wheat flour to verify possible effects of these ions on processing because, in addition to their nutritional importance, they are also responsible for water hardness. Calcium (0–1.30 g/100 g) and magnesium (0–0.34 g/100 g) ions from sulfate salts were added to wheat flour, according to a central composite rotatable design. The farinograph and extensigraph properties of wheat flour and its mixtures were evaluated. The results were analyzed by response surface methodology. Calcium ions stood out for increasing water absorption, decreasing mixing stability, and producing a delayed effect on dough extensibility (reduced at 135 min). Magnesium ions influenced most flour rheological properties in a similar manner to oxidizing agents (increased dough stability, increased resistance to extension, and reduced extensibility), thus proving to be a possible replacement agent for these additives. An interaction effect of the combined calcium and magnesium ions was observed on dough development time. The results showed that effects on processing can occur when wheat flour fortification is made, and adaptations on wheat flour specifications, product formulation, and processing parameters may be required.  相似文献   
10.
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