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   144篇
  免费   7篇
  2024年   1篇
  2023年   2篇
  2022年   7篇
  2021年   11篇
  2020年   6篇
  2019年   6篇
  2018年   3篇
  2017年   4篇
  2016年   11篇
  2015年   10篇
  2014年   5篇
  2013年   8篇
  2012年   11篇
  2011年   5篇
  2010年   12篇
  2009年   4篇
  2008年   5篇
  2007年   5篇
  2006年   8篇
  2005年   3篇
  2004年   12篇
  2003年   2篇
  2002年   4篇
  1999年   1篇
  1991年   1篇
  1988年   2篇
  1978年   2篇
排序方式: 共有151条查询结果,搜索用时 15 毫秒
141.
Plasmonics - Metallic core-shell substrate is specially used to serve ultrasensitive molecular detection down to concentration of micromolar level based on surface-enhanced Raman spectroscopy...  相似文献   
142.
143.
Plant and Soil - The objective of this paper was to develop a method based on infrared spectroscopy to compare mineral content in soils and apply it to evaluate soil mineralogical variations in...  相似文献   
144.
The kinetics of the uptake and efflux of 3-O-methyl-glucose in sporidia of Ustilago maydis were measured, both in active cells and in cells whose metabolic activity had been inhibited by azide and iodoacetate. The de-energized transport system proved to be carrier mediated with apparent affinity constants 13 +/- 2 mM outside (Ko) and 18 +/- 2 mM inside (K1). The apparent maximum rate constants for the same system were 0.66 +/- 0.05 mmol/1 cell water per min for uptake (V+) and 0.53 +/- 0.04 mmol/l cell water per min for efflux (V-). For the active system K0 = 0.08 +/- 0.01, K1 greater than 40, V+ = 9.7 +/- 0.5 and V- = 1.1 +/- 0.9 (in equivalent units). These results are discussed in the context of the carrier mechanism as proposed by Regen and Morgan (Regen, D.M. and Morgan, H.E. (1964) Biochim. Biophys. Acta 79, 151--166). The antifungal compound carboxin had no effect on de-energized transport but was shown to decrease both K0 And V+ in the active system. Phloretin and phlorizin were also found to be without effect on de-energized cells but the former enhanced while the latter inhibited active uptake.  相似文献   
145.
Constructed wetlands are of increasing interest worldwide given that they represent an eco-technological solution to many environmental problems such as wastewater treatment. Turkey possesses approximately 70% of the world's total boron (B) reserves, and B contamination occurs in both natural and cultivated sites throughout Turkey, particularly in the north-west of the country. This study analyzes B removal and plant uptake of B in pilot plots of subsurface horizontal-flow constructed wetlands. Constructed wetlands were vegetated with Typha latifolia (referred to as CW1) and Phragmites australis (referred to as CW2) to treat wastewater from a borax reserve in Turkey-the largest of its type in the world and were assessed under field conditions. The B concentrations of water inflows to the systems were determined to be 10.2, 28.2, 84.6, 232.3, 716.4, and 2019.1 mg l?1. The T. latifolia in the CW1treatment group absorbed a total of 1300 mg kg?1 B, whereas P. australis absorbed 839 mg kg?1. As a result, CW1had an average removal efficiency of 40.7%, while that of CW2was 27.2%. Our results suggest that constructed wetlands are an effective, economic and eco-friendly solution to treating B mine wastewater and controlling the adverse environmental effects of B mining.  相似文献   
146.
Molecular Biology Reports - Breeding strategies to improve modern varieties having high yield, high nutritional value and resistance to biotic and abiotic stress, etc. is very important to make up...  相似文献   
147.
Plinio Sist  Ervan Rutishauser  Marielos Peña-Claros  Alexander Shenkin  Bruno Hérault  Lilian Blanc  Christopher Baraloto  Fidèle Baya  Fabrice Benedet  Katia Emidio da Silva  Laurent Descroix  Joice Nunes Ferreira  Sylvie Gourlet-Fleury  Marcelino Carneiro Guedes  Ismail Bin Harun  Riina Jalonen  Milton Kanashiro  Haruni Krisnawati  Mrigesh Kshatriya  Philippa Lincoln  Lucas Mazzei  Vincent Medjibé  Robert Nasi  Marcus Vinicius N. d'Oliveira  Luis C. de Oliveira  Nicolas Picard  Stephan Pietsch  Michelle Pinard  Hari Priyadi  Francis. E. Putz  Ken Rodney  Vivien Rossi  Anand Roopsind  Ademir Roberto Ruschel  Nur Hajar Zamah Shari  Cintia Rodrigues de Souza  Farida Herry Susanty  Eleneide Doff Sotta  Marisol Toledo  Edson Vidal  Thales A.P. West  Verginia Wortel  Toshihiro Yamada 《应用植被学》2015,18(1):171-174
While attention on logging in the tropics has been increasing, studies on the long-term effects of silviculture on forest dynamics and ecology remain scare and spatially limited. Indeed, most of our knowledge on tropical forests arises from studies carried out in undisturbed tropical forests. This bias is problematic given that logged and disturbed tropical forests are now covering a larger area than the so-called primary forests. A new network of permanent sample plots in logged forests, the Tropical managed Forests Observatory (TmFO), aims to fill this gap by providing unprecedented opportunities to examine long-term data on the resilience of logged tropical forests at regional and global scales. TmFO currently includes 24 experimental sites distributed across three tropical regions, with a total of 490 permanent plots and 921 ha of forest inventories.  相似文献   
148.
Individual tree biomass equations were developed for a Tarchonanthus woodland and tested for their applicability in three woodland stands of Tarchonathus at Naivasha Kenya based on the felled tree measurements. Three homogenous woodland stands identified via the use of cluster analysis formed the basic sampling units. Forty-five Tarchonanthus camphoratus trees of varying diameter classes from 2 cm to 28 cm were selected and felled from the three stand types. Alternative relationships were analysed and the four best models are presented ( Tables 1 and 2 ). To test the accuracy of the developed models, a further fifteen trees per stand were felled and their dry weights calculated and compared with their estimated dry weights. For each model, validation was performed per stand with the aim of determining whether a particular model is applicable to a specific stand or to all stand types. The best model based on the adjusted R 2, standard error of estimate and distribution of residuals is presented and compared with previously existing equations. The model uses the square root transformed form of biomass. It was concluded that the model presented here could be used to estimate tree biomass in all stands of the woodland dominated by T. camphoratus , which in many places produces nearly pure stands, excluding other woody species . The fact that the accuracy of estimation tended to vary slightly from stand to stand suggests that the model may only apply to this woodland and to any other whose structure does not differ significantly from it.  

  Table 1  Equations for estimation of standing biomass of Tarchonanthus camphoratus trees  相似文献   

149.
Biological Trace Element Research - The use of cisplatin (CP) in chemotherapy of resistant cancers is limited due to its dose-dependent nephrotoxicity. Disulfiram (DSF), the aversion therapy for...  相似文献   
150.
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