全文获取类型
收费全文 | 250篇 |
免费 | 18篇 |
专业分类
林业 | 20篇 |
农学 | 8篇 |
68篇 | |
综合类 | 12篇 |
农作物 | 16篇 |
水产渔业 | 54篇 |
畜牧兽医 | 61篇 |
园艺 | 4篇 |
植物保护 | 25篇 |
出版年
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 12篇 |
2020年 | 9篇 |
2019年 | 15篇 |
2018年 | 16篇 |
2017年 | 6篇 |
2016年 | 12篇 |
2015年 | 9篇 |
2014年 | 13篇 |
2013年 | 16篇 |
2012年 | 17篇 |
2011年 | 21篇 |
2010年 | 13篇 |
2009年 | 6篇 |
2008年 | 15篇 |
2007年 | 12篇 |
2006年 | 13篇 |
2005年 | 16篇 |
2004年 | 9篇 |
2003年 | 4篇 |
2002年 | 10篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1987年 | 1篇 |
1983年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有268条查询结果,搜索用时 15 毫秒
91.
Speranza L Pesce M Patruno A Franceschelli S de Lutiis MA Grilli A Felaco M 《Marine drugs》2012,10(4):890-899
It has been suggested that oxidative stress activates various intracellular signaling pathways leading to secretion of a variety of pro-inflammatory cytokines and chemokines. SHP-1 is a protein tyrosine phosphatase (PTP) which acts as a negative regulator of immune cytokine signaling. However, intracellular hydrogen peroxide (H(2)O(2)), generated endogenously upon stimulation and exogenously from environmental oxidants, has been known to be involved in the process of intracellular signaling through inhibiting various PTPs, including SHP-1. In this study, we investigated the potential role of astaxanthin, an antioxidant marine carotenoid, in re-establishing SHP-1 negative regulation on pro-inflammatory cytokines secretion in U-937 cell line stimulated with oxidative stimulus. ELISA measurement suggested that ASTA treatment (10 μM) reduced pro-inflammatory cytokines secretion (IL-1β, IL-6 and TNF-α) induced through H(2)O(2), (100 μM). Furthermore, this property is elicited by restoration of basal SHP-1 protein expression level and reduced NF-κB (p65) nuclear expression, as showed by western blotting experiments. 相似文献
92.
A. Criniti E. Mazzoni S. Cassanelli P. Cravedi A. Tondelli D. Bizzaro G.C. Manicardi 《Pesticide biochemistry and physiology》2008,90(3):168-174
In this paper we analysed the basis of insecticide resistance in 59 Italian strains of the peach potato aphid Myzus persicae using both molecular and biochemical assays. Our data as a whole clearly indicate that most M. persicae strains (76.3%) have high or extremely high production of an esterase enzyme which sequester and detoxify insecticides with esteric group. Kdr genotypes conferring resistance towards pyrethoids are present in 57.7% of the analysed populations. Moreover, 26.5% of the kdr positive strains possess also the M918T mutation conferring super-kdr phenotype. Strains with modified AChE (MACE) are not so numerous (27.1%), although they can be found almost everywhere in Italy. Considering all the strains analysed, both MACE and kdr phenotypes are associated with high levels of esterase activity. In Central–Southern regions, kdr and MACE resistance mechanisms resulted in linkage disequilibrium. Bioassays performed in order to evaluate the efficacy of a pyrethroid insecticide against a strain possessing a F979S mutation within its para-type sodium channel gene suggests that this amino acid substitution could affect the sodium channel responsivity to pyrethroids. 相似文献
93.
Valenzuela A Campos V Yañez F Alveal K Gutiérrez P Rivas M Contreras N Klempau A Fernandez I Oyarzun C 《Fish physiology and biochemistry》2012,38(4):943-950
This paper describes and evaluates the mortality associated with the potential stressor effect induced by application of artificial photoperiods in rainbow trout (Oncorhynchus mykiss). After application of artificial photoperiods, high mortalities of trout subjected to this management were recorded (36% in LD 14:10 and 25% in LD 24:0) as compared to controls (7%). The recorded signology related to diseased trout included darkening, lethargy and erratic swimming. Among the morphological changes, skin lesions and ulcerative-type necrosis could be observed. Blood tests, histopathology and isolation of pathogens identified as Flavobacterium psychrophilum, associated with Aeromonas, Pseudomonas and Saprolegnia sp., were performed. The application of artificial photoperiods suggests that fish may be more susceptible to opportunistic diseases; thus, it is advisable to emphasize preventive measures in fish subjected to this management. 相似文献
94.
Effect of the addition of diatoms (Navicula spp.) and rotifers (Brachionus plicatilis) on water quality and growth of the Litopenaeus vannamei postlarvae reared in a biofloc system
下载免费PDF全文
![点击此处可从《Aquaculture Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Luis Otavio Brito Itala Gabriela Sobral dos Santos Jéssika Lima de Abreu Marcele Trajano de Araújo William Severi Alfredo Olivera Gàlvez 《Aquaculture Research》2016,47(12):3990-3997
The aim of this study was to evaluate the effect of the addition of Navicula spp. and Brachionus plicatilis on water quality and growth of postlarvae shrimp Litopenaeus vannamei reared in a biofloc system. Four treatments were considered: a control (biofloc system – BFT); BFT with the addition of Navicula spp. (BFT‐N); BFT with the addition of Brachionus plicatilis (BFT‐B) and BFT with the addition of Navicula spp. and Brachionus plicatilis (BFT‐NB), each in triplicate. Shrimp (16.2 ± 0.03 mg) were stocked at a density of 2500 shrimp m?3 and plankton were added on days 1, 5, 10, 15, 20, 25 and 30 at a density of 5 × 104 cells mL?1 (Navicula spp.) and 30 organisms L?1 (Brachionus plicatilis). The shrimp were fed a formulated feed in four daily rations composed of 40% crude protein and 8% lipids. Significant differences between treatments were observed for final weight, yield, feed conversion ratio, specific growth rate, protein efficiency ratio and protein content of the shrimp. The combined plankton addition of Navicula spp. and B. plicatilis had better performance parameters, indicating their benefit as natural food sources for postlarvae L. vannamei in biofloc systems. 相似文献
95.
96.
María Inés Pachecoy Ignacio Abel Ramirez Alfredo Marín Ana Clara Pontaroli 《Euphytica》2014,197(3):423-434
Rice is susceptible to cold during early developmental stages. Most tolerant cultivars have been developed for other conditions than those occurring in South America’s rice growing areas, or their grain type is not suitable for the local markets. If locally adapted varieties were available, growers could anticipate sowing date, making flowering time coincide with the moment of maximum solar radiation and increasing yields. In this work, 116 rice inbred lines and varieties of diverse origin within the South American gene pool were tested for seedling survival and germination percentage under low temperature in controlled conditions. As a result, lines used as controls responded as expected, whereas lines with similar behavior to controls, intermediate between susceptible and tolerant controls and more extreme than controls were detected at both seedling and germination stages. Allelic variation at candidate genes OsGSTZ1, OsGSTZ2 and OsCDPK13 was analyzed in a subset of ten contrasting lines. Ten out of thirty-four polymorphisms detected in all three genes were associated with cold tolerance in these lines. A functional marker, designed from an aminoacid-changing SNP found in gene OsGSTZ2, was tested in the 116 lines. As a result, a tight association was observed between cold tolerance and marker score. In conclusion, wide variability for cold tolerance at early developmental stages has been detected in rice advanced breeding materials that are adapted to local growing conditions. Also, a functional marker tightly associated with the trait is available for performing marker assisted selection. 相似文献
97.
Leandro Paiola Albrecht Alfredo Junior Paiola Albrecht André Felipe Moreira Silva Fábio Henrique Krenchinski Henrique Fabrício Placido Ricardo Victoria Filho 《Journal of Crop Science and Biotechnology》2018,21(3):211-216
Susceptibility to chlorimuron varies according to soybean genotype. STS® (sulfonylurea-tolerant soybean) presents a high tolerance to some sulfonylureas; this feature is determined by semi-dominants alleles, Als1 and Als2. Experiments were conducted in the field for four seasons with two cultivars for season to evaluate the selectivity of chlorimuron rates in post-emergency (V4) of glyphosate-tolerant and sulfonylurea-tolerant soybean. Data analysis made it possible to infer that there was no significant effect on the productivity of the cultivars when they received application in post-emergency, of chlorimuron at the doses used (0, 15, 30, 45, 60, 75, and 90 g ai ha-1). The maximum recommended rate for non-STS cultivars of chlorimuron is 20 g ai ha-1, or 4.5 times less than the maximum rate employed in this study. The soybean cultivars CD 250 RR/STS, CD 236 RR/STS, CD 2630 RR/STS, and BMX Turbo RR/STS were tolerant to the application, in post-emergency (V4) of the herbicide chlorimuron, until the rate of 90 g ai ha-1. 相似文献
98.
Rafael Alonso Ponce Sonia Roig Alfredo Bravo Miren del Río Gregorio Montero Marta Pardos 《European Journal of Forest Research》2017,136(5-6):983-996
Timber and biodiversity are considered two antagonistic ecosystem services (ES), largely influenced by silviculture and site ecological conditions. In order to address the trade-offs between these two ES over time, we performed a retrospective study at compartment level in the Pinus sylvestris forests of the Spanish Central Mountain System. Archival data from Management Plans for eight forests with contrasting silvicultural systems (uniform shelterwood system, group shelterwood system, irregular shelterwood system,) and three different site quality classes were analysed. Timber production was assessed through stand volume, harvested timber volume and a stand volume index. Biodiversity was examined through structural diversity (Gini index, Shannon tree size diversity index, Simpson’s reciprocal index and evenness index, all applied to diameter classes) and the abundance of large living trees. For all silvicultural systems investigated, stand volume and harvested timber volume have grown since the beginning of the management plans (beginning of the twentieth century in some forests). The largest yields of timber corresponded to the best quality sites with more intensive silvicultural treatments (uniform and group shelterwood systems). The uniform shelterwood system showed lower figures for structural diversity, though not always significant. The best site qualities maintained notable structural diversity values, even under the most intensive management system. The application of the different management systems over decades has revealed a synergy between timber production and structural diversity, particularly in those systems maintaining more than one age class, although results are conditioned by forest harvesting history. The interaction between historical silvicultural treatment and site quality has been identified as an important source of information to understand forest dynamics and functioning of ES provision. 相似文献
99.
Eva Guillamón Ana García-Lafuente Miguel Lozano Matilde D´Arrigo Mauricio A. Rostagno Ana Villares José Alfredo Martínez 《Fitoterapia》2010
Edible mushrooms are a valuable source of nutrients and bioactive compounds in addition to a growing appeal for humans by their flavors and culinary features. Recently, they have become increasingly attractive as functional foods for their potential beneficial effects on human health. Hence, food industry is especially interested in cultivated and wild edible mushrooms. 相似文献