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   552篇
  免费   41篇
林业   76篇
农学   16篇
  114篇
综合类   30篇
农作物   46篇
水产渔业   30篇
畜牧兽医   203篇
园艺   21篇
植物保护   57篇
  2023年   3篇
  2022年   3篇
  2021年   6篇
  2020年   7篇
  2019年   10篇
  2018年   39篇
  2017年   24篇
  2016年   35篇
  2015年   16篇
  2014年   29篇
  2013年   26篇
  2012年   37篇
  2011年   52篇
  2010年   22篇
  2009年   18篇
  2008年   28篇
  2007年   32篇
  2006年   28篇
  2005年   29篇
  2004年   18篇
  2003年   19篇
  2002年   16篇
  2001年   12篇
  2000年   11篇
  1999年   8篇
  1998年   2篇
  1997年   2篇
  1996年   4篇
  1995年   3篇
  1993年   4篇
  1987年   3篇
  1985年   3篇
  1981年   2篇
  1980年   2篇
  1977年   2篇
  1974年   2篇
  1973年   2篇
  1969年   2篇
  1968年   1篇
  1967年   1篇
  1966年   2篇
  1965年   2篇
  1964年   1篇
  1963年   4篇
  1958年   1篇
  1957年   1篇
  1956年   1篇
  1932年   1篇
  1926年   2篇
  1918年   2篇
排序方式: 共有593条查询结果,搜索用时 15 毫秒
591.
592.
As a result of the destruction of ammunition, mines, and explosive devices by the method of open detonation, the increased concentration of heavy metals is often recorded in the soil of military polygons, which is a serious ecological problem. However, in order to determine the potential risk of such locations to the environment, it is necessary to determine, in addition to the total content, the forms in which the metals are present. In this paper, a sequential extraction method was used to analyze the six fractions of five heavy metals (cadmium, lead, nickel, copper, and zinc) in the soil of the polygon for destruction of ammunition, mines, and explosive devices. Samples were collected from the place of direct detonation (so-called pits) and from the edge of the pit. The aim of this research is determination of metal speciation in order to obtain a better insight in their mobility and risk arising from this. The results showed that heavy metals are predominantly present in the residual, oxide, and organic fractions. Cd and Cu were also significantly present in the mobile fractions due to conducted activities on the polygon. To assess the potential environmental risk of soil, the risk assessment code (RAC) and individual (ICF) and global (GCF) contamination factors were used. According to the RAC, the mobility and bioavailability of the analyzed heavy metals decreases in the following order: Cd?>?Cu?>?Zn?>?Pb?>?Ni. ICF results show low to moderate risk, while GCF results show low risk in terms of heavy metal contamination in the examined area.  相似文献   
593.
The aim of this study was to determine the impact of two different treatments of early defoliation performed before blooming on: grape yield, chemical parameters, polyphenols content, and antioxidant activity of grape and red wine cv. Cabernet Sauvignon from the vineyard located in Ilok, the eastern continental region of Croatia. Two different treatments of leaf removal (LR) were performed: removal of 3 leafs (T1) and 6 leafs (T2) before blooming, together with control (no leaf removal) (T3) during two years (2013 and 2014). Crop yield and average cluster weights per vine were determined. Density, pH and titratable acidity were measured in must, while the total phenols, total anthocyanins and antioxidant activity were measured in the extract of grape skin and produced wine. The analysis of individual anthocyanins in wine was performed by HPLC method. T2 treatment significantly lowered the crop yield and the average cluster weights, and increased total phenols, total anthocyanins, antioxidant activity and most abundant individual anthocyanins in wine. Defoliation did not affect the other chemical parameters in must, grape skin extract and wine. Vintage year is statistically the most significant source of variability for density of must, antioxidant activity in grape skin extract, as well as pH and titratable acidity in wine. This study has showed that the early leaf removal treatment in eastern continental part of Croatia could be used for the production of smaller quantity of high quality Cabernet Sauvignon red wine abundant with anthocyanins.  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