全文获取类型
收费全文 | 193篇 |
免费 | 19篇 |
专业分类
林业 | 17篇 |
农学 | 6篇 |
49篇 | |
综合类 | 5篇 |
农作物 | 21篇 |
水产渔业 | 7篇 |
畜牧兽医 | 62篇 |
园艺 | 5篇 |
植物保护 | 40篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 8篇 |
2020年 | 11篇 |
2019年 | 13篇 |
2018年 | 11篇 |
2017年 | 8篇 |
2016年 | 10篇 |
2015年 | 15篇 |
2014年 | 6篇 |
2013年 | 8篇 |
2012年 | 15篇 |
2011年 | 13篇 |
2010年 | 11篇 |
2009年 | 7篇 |
2008年 | 14篇 |
2007年 | 12篇 |
2006年 | 11篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1996年 | 1篇 |
1992年 | 1篇 |
1983年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有212条查询结果,搜索用时 15 毫秒
171.
Stefano Moro Giovanna Jona‐Lasinio Barbara Block Fiorenza Micheli Giulio De Leo Fabrizio Serena Massimiliano Bottaro Umberto Scacco Francesco Ferretti 《Fish and Fisheries》2020,21(2):338-349
Conservation of apex predators is a key challenge both in marine and terrestrial ecosystems. The white shark is a rare but persistent inhabitant of the Mediterranean Sea and it is currently assessed as “critically endangered” in the region. However, the population trends and dynamics of this species in the area are still unknown. Little is known about white shark distribution, habitat use and population abundance trends, aspects that are critical for conservation and management. In this study, we built the most comprehensive database of white shark occurrence records in the region. We collected 773 different records from different sources and used them to characterize the spatial and temporal patterns of abundance of Mediterranean white sharks between 1860 and 2016. We analysed these data by using generalized additive models and used spatially disaggregated information on human population abundance as a proxy of observation effort. Our results suggest a complex trajectory of population change characterized by a historical increase and a more recent reduction (61%, range 58%–72%) since the second half of the 20th century. In particular, analyses reveal a 52% (range 37%–88%) to 96% (range 92%–100%) overall decline in different Mediterranean sectors and a contraction in spatial distribution. Here, we provide the first reconstruction of abundance trends and offer new hypotheses regarding the drivers of change of white sharks in the Mediterranean. Our approach can be broadly applied to data‐poor contexts to reconstruct change and inform the conservation of endangered top predators in the Mediterranean Sea and other intensely used marine regions. 相似文献
172.
Linseisen J Rohrmann S Norat T Gonzalez CA Dorronsoro Iraeta M Morote Gómez P Chirlaque MD Pozo BG Ardanaz E Mattisson I Pettersson U Palmqvist R Van Guelpen B Bingham SA McTaggart A Spencer EA Overvad K Tjønneland A Stripp C Clavel-Chapelon F Kesse E Boeing H Klipstein-Grobusch K Trichopoulou A Vasilopoulou E Bellos G Pala V Masala G Tumino R Sacerdote C Del Pezzo M Bueno-de-Mesquita HB Ocke MC Peeters PH Engeset D Skeie G Slimani N Riboli E 《Public health nutrition》2006,9(4):449-464
173.
Mohammad Yaghoubi Khanghahi Giovanna Cucci Giovanni Lacolla Loredana Lanzellotti Carmine Crecchio 《Soil Use and Management》2020,36(4):604-615
This research attempted to investigate a part of the United Nations sustainable development goal 15, dealing with preventing land degradation and halting the loss of microorganisms’ diversity. Since soil deterioration and biodiversity loss in the Mediterranean area are occurring because of intensive management, we evaluated some biochemical and microbiological parameters and bacterial biodiversity under long-term conventional tillage (CT) and no-tillage (NT) practices, in Basilicata, a typical Region of Southern Italy, characterized by a semiarid ecosystem. The highest biological fertility index (BFI) (composed of soil organic matter, microbial biomass C, cumulative microbial respiration during 25 days of incubation, basal respiration, metabolic quotient and mineralization quotient) was determined for the 0–20 cm of NT soil (class V, high biological fertility level). The analysis of the taxonomic composition at the phylum level revealed the higher relative abundance of copiotrophic bacteria such as Proteobacteria, Actinobacteria and Bacteroidetes in the NT soil samples as compared to the CT soil. These copiotrophic phyla, more important decomposers of soil organic matter (SOM) than oligotrophic phyla, are responsible of a higher microbial C use efficiency (CUE) in tilled soil, being microbial community composition, C substrates content and CUE closely linked. The higher Chao1 and Shannon indices, under the NT management, also supported the hypothesis that the bacterial diversity and richness increased in the no-till soils. In conclusion, we can assume that the long-term no-tillage can preserve an agricultural soil in a semiarid ecosystem, enhancing soil biological fertility level and bacterial diversity. 相似文献
174.
Angelstam Per Manton Michael Elbakidze Marine Sijtsma Frans Adamescu Mihai Cristian Avni Noa Beja Pedro Bezak Peter Zyablikova Iryna Cruz Fatima Bretagnolle Vincent Díaz-Delgado Ricardo Ens Bruno Fedoriak Mariia Flaim Giovanna Gingrich Simone Lavi-Neeman Miri Medinets Sergey Melecis Viesturs Muñoz-Rojas Jose Schäckermann Jessica Stocker-Kiss Andrea Setälä Heikki Stryamets Natalie Taka Maija Tallec Gaelle Tappeiner Ulrike Törnblom Johan Yamelynets Taras 《Landscape Ecology》2019,34(7):1461-1484
Landscape Ecology - Place-based transdisciplinary research involves multiple academic disciplines and non-academic actors. Long-Term Socio-Ecological Research (LTSER) platform is one concept with ~... 相似文献
175.
Sessa M Tsao R Liu R Ferrari G Donsì F 《Journal of agricultural and food chemistry》2011,59(23):12352-12360
Resveratrol was encapsulated in oil-in-water food-grade nanoemulsions of subcellular size, produced by high-pressure homogenization. Physicochemical stability was evaluated under accelerated aging (high temperature and UV light exposure), as well as during simulated gastrointestinal digestion. Antioxidant activity was assessed at different stages of digestion by chemical assays and by an improved cellular assay, to measure exclusively the residual activity of resveratrol that penetrated inside Caco-2 cells. Results showed that the nanoemulsions based on soy lecithin/sugar esters and Tween 20/glycerol monooleate were the most physically and chemically stable, in terms of mean droplet size (always <180 nm) and resveratrol loading, during both accelerated aging and gastrointestinal digestion. These formulations also exhibited the highest chemical and cellular antioxidant activities, which was comparable to unencapsulated resveratrol dissolved in DMSO, suggesting that nanoencapsulated resveratrol, not being metabolized in the gastrointestinal tract, can be potentially absorbed through the intestinal wall in active form. 相似文献
176.
Chestnut stands (orchards and coppices) are among the most typical elements of the southern European mountain landscape and
a protected habitat (9260 Castanea sativa woods) according to the European Union (Directive 92/43/EEC). As an anthropogenic landscape, they require specific measures
to address preservation or to guide their evolutionary trend. In the Northern Apennines, a landscape multiscalar-multitemporal
approach was adopted to highlight factors that have acted on the evolution of this habitat and which still might affect either
its preservation or its evolutionary dynamics. Using a diachronic GIS-approach, we analyzed old cadastral maps (drawn up 200 years
ago), and aerial photographs. Both the present distribution pattern of the woody species and the incidence of important chestnut
diseases were also surveyed. The factors explaining the current extent and species composition of the local chestnut forests
confirm their status as an anthropogenic habitat. The present landscape distribution of chestnut woods is heavily linked to
past human settlements. Chestnut blight and ink disease are more an indirect reason for past felling activities than an actual
direct cause of damage to trees, because of the hypovirulence spread and the limited incidence of the ink disease. Vegetation
dynamics of abandoned chestnut forests evolved only partly towards deciduous Beech and Hop Hornbeam stands, thus suggesting
both the possibility of a recovery of this cultivation and the need for new criteria for its management. 相似文献
177.
Fragoulis G Merli A Reeves G Meregalli G Stenberg K Tanaka T Capri E 《Pest management science》2011,67(6):656-664
BACKGROUND: Quinoxyfen is a fungicide of the phenoxyquinoline class used to control powdery mildew, Uncinula necator (Schw.) Burr. Owing to its high persistence and strong sorption in soil, it could represent a risk for soil organisms if they are exposed at ecologically relevant concentrations. The objective of this paper is to predict the bioconcentration factors (BCFs) of quinoxyfen in earthworms, selected as a representative soil organism, and to assess the uncertainty in the estimation of this parameter. Three fields in each of four vineyards in southern and northern Italy were sampled over two successive years. RESULTS: The measured BCFs varied over time, possibly owing to seasonal changes and the consequent changes in behaviour and ecology of earthworms. Quinoxyfen did not accumulate in soil, as the mean soil concentrations at the end of the 2 year monitoring period ranged from 9.16 to 16.0 µg kg?1 dw for the Verona province and from 23.9 to 37.5 µg kg?1 dw for the Taranto province, with up to eight applications per season. To assess the uncertainty of the BCF in earthworms, a probabilistic approach was used, firstly by building with weighted bootstrapping techniques a generic probabilistic density function (PDF) accounting for variability and incompleteness of knowledge. The generic PDF was then used to derive prior distribution functions, which, by application of Bayes' theorem, were updated with the new measurements and a posterior distribution was finally created. CONCLUSION: The study is a good example of probabilistic risk assessment. The means of mean and SD posterior estimates of log BCFworm (2.06, 0.91) are the ‘best estimate values’. Further risk assessment of quinoxyfen and other phenoxyquinoline fungicides and realistic representative scenarios for modelling exercises required for future authorization and post‐authorization requirements can now use this value as input. Copyright © 2011 Society of Chemical Industry 相似文献
178.
179.
180.
Vladimíra Oceov Remigius Chizzola Giovanna Battelli Jana Pisarcikova Stefan Faix Francesco Gai Iveta Placha 《Journal of animal physiology and animal nutrition》2019,103(1):204-209
Plant compounds occurring in phytogenic feed additives are involved in different pharmacological activities in the animal organism. Since the digestive tract acts as a first line of defence against foreign compounds, it is necessary to outline its response to dietary supplementation with bioactive plant components. Little information is available on the bioactivity of thymol as the main bioactive compound of Thymus vulgaris L. essential oil (TEO). The main objective of the present study was to provide a detailed view of the concentrations of thymol in plasma and the content of individual intestinal segments (duodenum, jejunum, ileum, caecum and colon) of broiler chickens after 4 weeks of dietary supplementation with different TEO concentrations. 32 one‐day old Ross 308 hybrid broilers were randomly divided into four dietary treatment groups (0.00%, 0.01%, 0.05%, 0.1% w/w of TEO in the diet). Thymol concentrations in the duodenal chyme presented around 7% on average from the thymol amount administered in the feed. A significantly increased thymol amount was observed after 0.1% TEO addition to the diet compared with 0.01% TEO enrichment in the duodenal wall and gut content of jejunum, ileum, caecum and colon (p < 0.05). Thymol levels in the colon were significantly higher than in the ileum and about 1.7 times higher on average than those in the caecum. Significant coefficient of correlation was observed between thymol concentrations in plasma and feed, gut content of all intestinal segments as well as duodenal wall. Our results point to intensive thymol absorption in the initial sections of the digestive tract. In the current study, the role of intestine in biotransformation of thymol was observed, and it would be desirable to investigate whether thymol itself or thymol metabolites are responsible for beneficial effects in intestine. 相似文献