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   216篇
  免费   19篇
  235篇
  2023年   1篇
  2022年   4篇
  2021年   4篇
  2020年   1篇
  2019年   3篇
  2018年   10篇
  2017年   7篇
  2016年   10篇
  2015年   14篇
  2014年   20篇
  2013年   16篇
  2012年   24篇
  2011年   18篇
  2010年   13篇
  2009年   8篇
  2008年   8篇
  2007年   10篇
  2006年   7篇
  2005年   6篇
  2004年   9篇
  2003年   8篇
  2002年   7篇
  2001年   3篇
  2000年   4篇
  1999年   2篇
  1998年   2篇
  1997年   1篇
  1996年   3篇
  1994年   3篇
  1991年   1篇
  1990年   1篇
  1987年   2篇
  1980年   1篇
  1979年   1篇
  1978年   2篇
  1976年   1篇
排序方式: 共有235条查询结果,搜索用时 15 毫秒
41.
42.
This paper reviews some of the results and the speculations presented at the Torino CD38 Meeting in June, 2006 and focused on CD38 and CD157 seen as a family of molecules acting as surface receptors of immune cells. This partisan view was adopted in the attempt to combine the enzymatic functions with what the immunologists consider key functions in different cell models. At the moment, it is unclear whether the two functions are correlated, indifferent, or independent. Here we present conclusions inferred exclusively on human cell models, namely T and B lymphocytes, dendritic cells, and granulocytes. As an extra analytical tool, we try to follow in the history of life when the enzymatic and receptorial functions were generated, mixing ontogeny, membrane localization, and cell anchorage.  相似文献   
43.
44.
Current status and future perspectives of Italian finfish aquaculture   总被引:1,自引:0,他引:1  
Currently available data show that shellfish and finfish production in Italy, derived both from fisheries and aquaculture activities, is on the order of 474,000 tons, each activity representing 50 % of the total amount. In this context, the finfish aquaculture industry contributes on average 31 % to the national aquaculture production and on average 59 % of its value, giving a total amount of 72,000 tons and a value of around 351 million € (2010). According to FEAP statistics, Italy is the fourth largest finfish producer in EU27, after the UK, Greece, and Spain, while it is also one of the six largest finfish producers among the non-EU and EU member countries, together with Norway, UK, Greece, Turkey, and Spain. Presently, fish culture activities are mainly focused on rainbow trout (Oncorhynchus mykiss, 55.5 %), followed by European sea bass (Dicentrarchus labrax, 13.6 %), gilthead sea bream (Sparus aurata, 12.2 %), gray mullet (Mugil cephalus, 5.3 %), sturgeon (Acipenser spp., 2 %), and European eel (Anguilla anguilla, 1.7 %). Over the last 20 years, freshwater fish production and aquaculture (trout, carp, and eel) have decreased in Italy, with the exception of sturgeon. In contrast, marine fish production has significantly increased during the same period, and the two leading species, European sea bass and gilthead sea bream, presently contribute 25.8 % of the finfish production. From 1,900 tons in 1990, production reached 19,000 tons in 2010, with a 900 % increase, at an average percentage of 4.5 %. In addition, new marine fish species were successfully cultured over the same period. This review outlines the past and present situation of finfish culture in Italy and discusses future developments and priorities, with particular emphasis on new, emerging aquaculture species.  相似文献   
45.
In this paper we review drift-feeding models for stream salmonids. We assess their historical development and current state, and we propose areas for future research. Drift-feeding models serve as the critical input for energetics-based habitat selection and habitat quality models, which have recently begun to see widespread use for predicting salmonid distribution, growth and abundance. We use a bibliometric approach to find drift-feeding model publications, especially those citing three landmark papers that began the quantification of drift feeding by stream fish (Fausch 1984; Hughes and Dill 1990; Hill and Grossman 1993). Subsequent drift-feeding models have largely been built upon these models. Research effort has focused on model development and applications but model testing has been neglected. To date, the only rigorous test of a drift-feeding model (Hughes et al. 2003) identified several limitations and violations of model assumptions. The most important limitation was that prey capture- and gross energy intake rates were overestimated by a factor of two, due largely to poor predictions of prey detection probabilities. Consequences of error in drift-feeding models, and consequently in the habitat selection/quality models that employ them, are greater for applications aimed at predicting growth and abundance than they are for predicting distribution. Research effort on a broad front is needed to advance both drift-feeding models and habitat selection/quality models, including: further development of drift-foraging theory, revision and testing of drift-feeding models (specifically new, functional prey detection and interception sub-models), and revision of habitat selection/quality models to incorporate spatial, temporal, and flow-dependent variation in drift concentration.  相似文献   
46.
Monda  Hiarhi  Cozzolino  Vincenza  Vinci  Giovanni  Drosos  Marios  Savy  Davide  Piccolo  Alessandro 《Plant and Soil》2018,429(1-2):407-424
Plant and Soil - The use of composted agricultural wastes as source of biostimulant compounds provides an added value to the recycling of biomasses. This study aims to expand the knowledge on the...  相似文献   
47.
Prey capture success and foraging mode were studied in brown trout Salmo trutta at temperatures ranging from 5.7 to 14.0° C. At low temperatures, there was a positive correlation between prey capture success and the proportion of time that the fish spent holding feeding stations. This correlation was not found at temperatures >10° C.  相似文献   
48.
49.
In the search for compounds with potential for development as positron emission tomography radioligands for brain D3 receptor imaging, a series of N-[4-(4-arylpiperazin-1-yl)butyl]arylcarboxamides with appropriate lipophilicity (2 < log P < 3.5) were synthesized and tested in vitro. Some of the final compounds showed moderate-to-high dopamine D3 receptor affinities but lacked selectivity over D2 receptors.  相似文献   
50.
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