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   911篇
  免费   71篇
  2023年   5篇
  2022年   19篇
  2021年   34篇
  2020年   24篇
  2019年   22篇
  2018年   37篇
  2017年   31篇
  2016年   61篇
  2015年   54篇
  2014年   69篇
  2013年   60篇
  2012年   72篇
  2011年   71篇
  2010年   34篇
  2009年   29篇
  2008年   56篇
  2007年   46篇
  2006年   30篇
  2005年   38篇
  2004年   30篇
  2003年   26篇
  2002年   31篇
  2001年   12篇
  2000年   13篇
  1999年   13篇
  1998年   6篇
  1997年   4篇
  1996年   3篇
  1995年   4篇
  1994年   4篇
  1993年   2篇
  1992年   3篇
  1991年   6篇
  1990年   3篇
  1989年   4篇
  1988年   7篇
  1987年   4篇
  1986年   2篇
  1985年   1篇
  1983年   4篇
  1982年   1篇
  1980年   1篇
  1978年   1篇
  1975年   2篇
  1973年   2篇
  1965年   1篇
排序方式: 共有982条查询结果,搜索用时 31 毫秒
961.
Summary A glasshouse experiment was conducted to determine how reduction conditions would affect plant nutrient availability and uptake in a red-yellow latosol (Acrustox). Soil analysis showed that the most important changes were a marked increase in extractable iron and an inhibition of nitrification. The grass andropogon (Andropogon gayanus Kunth var.bisquamulatus (Hoechst) Hack) and the legume stylo (Stylosanthes capitata (Vog)) responded differently to reducing conditions.Andropogon showed low P, Ca, Mg, Fe and Mn content in the shoots but an intense coating of oxidized iron was observed on the surface of roots. Stylo plants, on the other hand, showed no iron deposition on the root surfaces but a high iron content in the shoots. No decreased P, Ca or Mg content was observed in this case. It was concluded that in water saturated soil, reduction took place and plant performance was affected not only by restricted root development but by preventing P, Ca and Mg uptake in andropogon and increasing Fe uptake in stylo plants. It is suggested that restricted P, Ca and Mg uptake by andropogen would be the result of iron deposition on root surfaces.  相似文献   
962.
963.
964.
EcoHealth - We verified the clinical–epidemiological, microbiological, and molecular aspects of feline sporotrichosis in Espírito Santo, Brazil, as well as demonstrated the degree of...  相似文献   
965.
966.
967.
968.
Orthobiologics are biological materials that are intended for the regeneration or healing of bone,cartilage and soft tissues.In this review we discuss the use of orthobiologics for hip disorders providing an update.The orthobiologics included in this article are hyaluronic acid,platelet rich plasma,bone marrow,adipose tissue and expanded mesenchymal stem cells.We explain the concepts and definitions of each orthobiological product,and the literature regarding its use in the hip joint.The paucity of guidelines for the production and characterization of the biological products leads to uneven results across the literature.Each biologic therapy has indications and benefits;however,noteworthy are the characterization of the orthobiologics,the application method and outcome analysis for further improvement of each technique.  相似文献   
969.
970.
Abstract

Reverse osmosis is a widely known technology used to produce fresh water from brackish waters. However, the reject brine from desalination plants poses a serious threat to the environment due to soil and groundwater salinization. The aim of this study was to investigate the potential of Atriplex nummularia to extract salts from a soil irrigated with reverse osmosis brine, at varying moisture levels. A field experiment was conducted in a split-plot design, with randomized complete blocks replicated four times. Treatments consisted of irrigation with reject brine in the main plots, with four relative percentages of the soil moisture at field capacity (100, 85, 70, and 50%), and two levels of organic fertilization in the subplots (0 and 1.5?L plant?1 of goat manure). The mineral composition of leaves and stems indicated that the highest salt extraction by plants occurred when soil moisture was maintained at 100% field capacity. The salt extraction capacity of A. nummularia indicates a high potential for phytoremediation of soils affected by brine disposal from reverse osmosis plants.  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