全文获取类型
收费全文 | 76篇 |
免费 | 2篇 |
专业分类
林业 | 5篇 |
农学 | 2篇 |
22篇 | |
综合类 | 4篇 |
农作物 | 2篇 |
水产渔业 | 6篇 |
畜牧兽医 | 25篇 |
园艺 | 3篇 |
植物保护 | 9篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2014年 | 4篇 |
2013年 | 3篇 |
2012年 | 3篇 |
2011年 | 12篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 9篇 |
2007年 | 5篇 |
2006年 | 7篇 |
2005年 | 4篇 |
2004年 | 5篇 |
2003年 | 2篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1999年 | 1篇 |
1993年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有78条查询结果,搜索用时 15 毫秒
71.
Pablo del Monte-Luna Daniel Lluch-Belda Elisa Serviere-Zaragoza Roberto Carmona Héctor Reyes-Bonilla David Aurioles-Gamboa José Luis Castro-Aguirre Sergio A. Guzmán del Próo Oscar Trujillo-Millán & Barry W. Brook 《Fish and Fisheries》2007,8(2):107-122
In recent years, more than 130 extinctions have been estimated to have occurred in the marine realm. Here we review this body of evidence and show that this figure may actually be overestimated by as much as 50%. We argue that previous estimates have not fully taken into account critical uncertainties such as naturally variable geographical distributions, and have misinterpreted documentary evidence. However, current evidence indicates that some sharks, rays and reef‐associated species, although not necessarily geographically restricted, are particularly vulnerable to anthropogenic impacts and now occur in very low numbers. Overestimating extinctions is of concern because it could reduce confidence in the credibility of the ‘extinct’ category in threatened species lists and, ultimately, be used to question the integrity of conservation and management policies. We suggest that when integrating future checklists of marine extinct species, there needs to be a more rigorous use of the terminology of extinction, and participation by specialists in each of the particular taxonomic groups involved. 相似文献
72.
The effect of high dietary protein intake on proteolytic enzyme activity of feeding juvenile Asian sea bass, Lates calcarifer (Bloch) was studied. Ninety fish [mean body weight ± standard error (SE) 304.62 ± 34.84 g] were randomly assigned to two dietary treatments, each with three replicates. In treatment 1, fish were fed by‐catch (Thunnus albacares) and in treatment 2, a formulated diet containing 50% protein. Proteolytic enzyme activity was determined in pyloric caecae and intestine at day 0, 7, 15, and 30. Initial proteolytic enzyme activity in sea bass ranged from 174 to 232 azocasein units (UAC.) per mg of protein. After 7 days there was no significant difference in proteolytic enzyme activity of fish fed the two diets. However, a marked increase was observed in fish fed the formulated diet at day 15. After 30 days, the proteolytic enzyme activity in fish fed the formulated diet was threefold higher than that in fish fed the by‐catch diet. Fish fed the formulated diet had significantly higher total protein intake at day 7 than did fish fed by‐catch. Thereafter, a twofold weekly increase in the total protein intake was observed in both fish fed the by‐catch and formulated diets until day 30. These results suggest that a high dietary protein intake induces increased proteolytic enzyme activity in Asian sea bass. 相似文献
73.
Gabriel L. Cicuttin Diego F. Brambati María F. De Gennaro Fernando Carmona María L. Isturiz Laura E. Pujol Guillermo C. Belerenian Horacio Gil 《Veterinary microbiology》2014
In Argentina, data on the presence of members of the genus Bartonella is scarce. To increase knowledge about these zoonotic pathogens in this country, the presence and variability of Bartonella spp. was investigated in cats and dogs from Buenos Aires. Bartonella spp. was detected in 17.8% of cats, while all dogs tested negative by PCR and Reverse Line Blot. B. henselae was the most frequent species, being detected in 11.9% (14/101), while B. clarridgeiae was found in only 5.9% (6/101) of the cats. Afterwards, B. henselae isolates and positive blood samples were characterized by Multiple Locus Sequence Typing (MLST) and Multiple Locus Variable Number Tandem Repeats Analysis (MLVA). As result, four different MLST sequence types (ST) and eight MLVA profiles were identified. ST 1 was the most frequent variant found in cats, followed by ST 8. Interestingly, some of the MLVA profiles that were detected in this study have been previously associated with human disease, and represents a potential risk of infection. Veterinarians and physicians should consider the presence of these emerging pathogens in their diagnostic routine. 相似文献
74.
Many aquaculture industries generate a nutrient-rich waste stream that can lead to eutrophication of coastal waters. To address this environmental issue, the bioremediation potential of several native Northeast American species of Porphyra was assessed and compared to the well-known Asian species. Porphyra thalli were cultured over 4 weeks at 15 °C at a stocking density of 0.4 g FW L− 1. At 3- to 4-day intervals nutrient uptake, tissue N accumulation and phycobiliprotein concentration (PBP) were determined as functions of nitrogen (N) concentration (25-300 μM) and N source (nitrate vs. ammonium). Growth rates were measured weekly. Growth and tissue N reached maximal levels at inorganic N concentrations of 150-300 μM. Maximum growth rates ranged from 10% to 25% day− 1, although induction of archeospores reduced average growth rates in many cases. No evidence of ammonium toxicity (reductions in growth rate) was observed; in fact, similar values were found with both N sources. Ammonium generally yielded higher PBP and tissue N contents than nitrate. Porphyra amplissima presented the highest growth rate, followed by the Asian Porphyra yezoensis. Under the experimental conditions, Porphyra spp. removed 70-100% of N within 3-4 days at N concentrations up to 150 μM, but was less efficient in removing inorganic phosphorus (35-91% removal). The highest tissue N and PBP concentrations were found at 150-300 μM of N, with N values close to 7% DW. Overall, Porphyra appears to be an excellent choice for bioremediation of moderately eutrophic effluents, with the added benefit that tissue may be harvested for sale. 相似文献
75.
MAGIC Collaboration Albert J Aliu E Anderhub H Antonelli LA Antoranz P Backes M Baixeras C Barrio JA Bartko H Bastieri D Becker JK Bednarek W Berger K Bernardini E Bigongiari C Biland A Bock RK Bonnoli G Bordas P Bosch-Ramon V Bretz T Britvitch I Camara M Carmona E Chilingarian A Commichau S Contreras JL Cortina J Costado MT Covino S Curtef V Dazzi F De Angelis A De Cea Del Pozo E de Los Reyes R De Lotto B De Maria M De Sabata F Mendez CD Dominguez A Dorner D Doro M Errando M Fagiolini M 《Science (New York, N.Y.)》2008,320(5884):1752-1754
The atmospheric Cherenkov gamma-ray telescope MAGIC, designed for a low-energy threshold, has detected very-high-energy gamma rays from a giant flare of the distant Quasi-Stellar Radio Source (in short: radio quasar) 3C 279, at a distance of more than 5 billion light-years (a redshift of 0.536). No quasar has been observed previously in very-high-energy gamma radiation, and this is also the most distant object detected emitting gamma rays above 50 gigaelectron volts. Because high-energy gamma rays may be stopped by interacting with the diffuse background light in the universe, the observations by MAGIC imply a low amount for such light, consistent with that known from galaxy counts. 相似文献
76.
Ana de Santiago José M. Quintero Eusebio Carmona Antonio Delgado 《Biology and Fertility of Soils》2008,44(6):875-883
The main objective of this work was to study the influence of humic substances (HS) on the effectiveness of Fe sulfate and
Vivianite in preventing Fe chlorosis in white lupin with a view of performing cost-effective methods to overcome the problem.
Two consecutive crops were performed using calcareous sand treated with different Fe sources (FeSO4·7H2O and Vivianite, at three different rates, and Fe-EDDHA) and five HS rates. Vivianite was more effective and persistent than
Fe sulfate in increasing Soils and Plant Analysis Development (SPAD) readings and lupin yield expressed as dry matter (DM),
probably due to the type of alteration products formed upon Vivianite oxidation. The effect of Fe sulfate and Vivianite in
preventing Fe chlorosis was significantly increased by HS, and the best results were obtained with Vivianite and HS applied
at 0.32 g Fe kg−1 and 0.06 g kg−1 growing media, respectively. SPAD readings with this treatment accounted for 85% and 70% of those obtained with Fe-EDDHA
in the first and second crop, respectively, whereas DM production was greater with the Vivianite + HS treatment than with
Fe-EDDHA. These results showed the potential effectiveness of treatments based on the application of Vivianite and HS in overcoming
Fe chlorosis. However, HS applied with Fe sources at rates of 0.5 and 1 g kg−1 growing media decreased SPAD readings and plant yield. These positive and negative effects of HS in preventing Fe chlorosis
were more evident with Fe sulfate and Vivianite than with chelated Fe, probably due to the effect of HS on the solubility
of Fe forms of the growing medium. 相似文献
77.
Herrero AM Carmona P García ML Solas MT Careche M 《Journal of agricultural and food chemistry》2005,53(7):2558-2566
The ultrastructural changes and the main Raman spectral features of water (3100-3500 and 50-600 cm(-)(1) ranges) in frozen-stored hake were studied with the aim of connecting these changes with loss of some functional properties such as water holding capacity, and with modifications of muscle texture. The following results were obtained: (a) The changes in the spaces between myofibrils can be related to modifications of shear resistance. (b) The behavior of the strong 160 cm(-)(1) band can be related to conformational transitions of muscle proteins, to changes in the structure of muscle water, and/or to alterations in protein-water interactions. (c) There were intensity changes in the nu(s)(OH) band that may be attributable to transfer of water to larger spatial domains during frozen storage. 相似文献