全文获取类型
收费全文 | 208篇 |
免费 | 16篇 |
专业分类
林业 | 17篇 |
农学 | 7篇 |
48篇 | |
综合类 | 2篇 |
农作物 | 13篇 |
水产渔业 | 41篇 |
畜牧兽医 | 71篇 |
园艺 | 4篇 |
植物保护 | 21篇 |
出版年
2023年 | 4篇 |
2022年 | 6篇 |
2021年 | 10篇 |
2020年 | 8篇 |
2019年 | 14篇 |
2018年 | 23篇 |
2017年 | 13篇 |
2016年 | 16篇 |
2015年 | 12篇 |
2014年 | 23篇 |
2013年 | 6篇 |
2012年 | 18篇 |
2011年 | 15篇 |
2010年 | 9篇 |
2009年 | 6篇 |
2008年 | 12篇 |
2007年 | 4篇 |
2006年 | 7篇 |
2005年 | 8篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 1篇 |
排序方式: 共有224条查询结果,搜索用时 31 毫秒
221.
Jacek Bełdowski Marta Szubska Magdalena Bełdowska Katarzyna Jankowska Ewa Kotlarska Bożena Graca 《Journal of Soils and Sediments》2018,18(12):3424-3436
Purpose
Mercury speciation in sediments is linked to environmental conditions and processes. Domination of particular mercury species depends on its source, displays considerable seasonal behavior, and may be further modified due to oxygen levels, icing conditions, or the input of fresh organic matter. The purpose of this study was to examine the coastal area of the Gulf of Gdańsk in terms of mercury contamination and the influence of seasonal environmental changes on its speciation.Materials and methods
In three highly dynamic coastal sites, mercury speciation in sediments was studied in relation to other environmental parameters (redox conditions, organic matter concentration, bacteria abundance, etc.). Sediment and water samples were collected monthly during a 3-year study. Sequential extraction of sediments was used for identification of four inorganic mercury species: dissolved, bound with fulvic and humic acids, mercury sulfide, and residual fraction. Cold vapor atomic fluorescence spectrometry (CV-AFS) was used for extracts and liquid sample analysis. Total mercury in sediments was measured with atomic absorption spectrometry (AAS). Changes in salinity were analyzed by measurements of chloride and sulfate ion concentrations using ion chromatography. Bacteria number and biomass were measured by direct counting using epifluorescence microscopy.Results and discussion
Seasonal changes in mercury speciation were observed at all sites and attributed to different processes. Labile mercury fraction contribution varied from 0 to 80%. The speciation patterns varied locally as the stations selected for the study are diversified in terms of anthropogenic impact, water dynamics, and output from land. Mercury concentrations at all stations fluctuated during phytoplankton blooms, icing of marine waters, precipitation, or increased surface runoff from the land. In this local scale, the global climate changes are visible already as environmental conditions in studied area changed in comparison to elder research.Conclusions
Obtained results suggest that although mercury emissions to the environment have decreased in recent years, local weather conditions, which may be intensified by climate change, seriously affect the bioavailability of past mercury deposits in coastal sediments.222.
Katarzyna Kowalczewska-Madura Renata Dondajewska Ryszard Gołdyn Anna Kozak Beata Messyasz 《Water, air, and soil pollution》2018,229(8):280
The ribbon type Lake Durowskie (Western Poland) is currently undergoing a sustainable restoration process due to water quality deterioration, manifested in water blooms, low transparency, and oxygen deficits near the bottom sediments. Three restoration methods were applied: (i) hypolimnion aeration using two wind-driven pulverizing aerators installed at the deepest places, (ii) phosphorus inactivation using small doses of iron sulfate and magnesium chloride several times a year, and (iii) biomanipulation using pike fry stocking. Research on the exchange of phosphorus in the sediment-water interphase was conducted in the years 2009–2016 to determine the multiannual changes of internal phosphorus loading from bottom sediments during the restoration process. The sustainable approach resulted in a decrease of internal phosphorus loading and a gradual increase in the sorption capacity of bottom sediments, particularly noticeable in the last 2 years. The content of phosphorus in the sediment and in the interstitial water fluctuated, showing an increase during the first years of restoration and then a gradual decrease. It was proved that the process of sustainable restoration is cheap and does not interfere strongly with the ecosystem, although it is long-lasting. It should be continued for many years, especially in the case of continuous external loading of the lake with nutrients from the catchment area, i.e., until the water quality in the main tributary improves and the lake ecosystem stabilizes. 相似文献
223.
Agnieszka Piernik Katarzyna Hrynkiewicz Anna Wojciechowska Sonia Szymańska Marta Izabela Lis Adele Muscolo 《Archives of Agronomy and Soil Science》2017,63(10):1404-1418
The aim of this study was to determine the influence of selected halotolerant endophytic bacteria isolated from the roots of Salicornia europaea on the growth parameters of Beta vulgaris under different concentrations of salinity. Two endophytic strains were selected as inocula for the pot experiment: Pseudomonas sp. ISE-12 (B1) and Xanthomonadales sp. CSE-34 (B2). Surface-sterilised seeds were incubated in the bacterial inoculation suspensions before sowing and cultivated in a sterile mixture of sand and vermiculite (1:1). Six salinity treatments were taken into account: 0, 50, 100, 150, 200 and 300 mM NaCl. Inoculation of seeds with B1 and B2 positively affected germination percentage and germination index and shortened mean germination time, which led to a quickening of the growth stages of seedlings. After 42 days inoculated plants had, in general, a greater root length, higher dry biomass, lower tissue water content and lower specific leaf area compared with the control. While the positive effect of B2 bacteria was visible only at low salinity, strain B1 stimulated plant growth at higher salinities (200 and 300 mM NaCl). We suggest that the superior growth promotion observed for B1 may be related to the higher metabolic activity of these bacteria. 相似文献
224.
Magdalena Kroc Wojciech Rybiński Paulina Wilczura Katarzyna Kamel Zygmunt Kaczmarek Paweł Barzyk Wojciech Święcicki 《Genetic Resources and Crop Evolution》2017,64(8):1853-1860
White lupin (Lupinus albus L.) has unexploited potential as a crop plant due to its high seed yield as well as protein and oil content in seeds. Well-characterized collections of gene resources are very important for breeding as a source of genetic variation. This paper presents the results of analyses for total content and qualitative composition of alkaloids in seeds of 367 L. albus accessions from the Polish Genebank. Accessions were divided into four classes of origin: wild collected material, land races, breeding lines, and cultivars. Apart from the expected broad variation as well as strong differentiation in the alkaloid content, a clear influence of domestication was observed. This was shown as an apparent decrease in the alkaloid content in breeding lines and cultivars classes. The total alkaloid content varies from 0.02 to 12.73% of the seed dry weight. Six major alkaloids (abundance >1%) were revealed: lupanine (28.22–94.49%, mean 76.06% in total content), 13-hydroxylupanine (0.10–32.78%, mean 8.23%), multiflorine (0.00–21.67%, mean 5.52%), albine (0.00–18.55%, mean 4.48%), angustifoline (0.24–12.14%, mean 2.07%), 11,12-seco-12,13-didehydromultiflorine (0.00–12.28%, mean 1.74%). Owing to its abundance, lupanine was found to be the most closely correlated to the total alkaloid content. 相似文献