全文获取类型
收费全文 | 369篇 |
免费 | 27篇 |
专业分类
林业 | 36篇 |
农学 | 29篇 |
63篇 | |
综合类 | 12篇 |
农作物 | 17篇 |
水产渔业 | 76篇 |
畜牧兽医 | 99篇 |
园艺 | 10篇 |
植物保护 | 54篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 11篇 |
2021年 | 23篇 |
2020年 | 19篇 |
2019年 | 28篇 |
2018年 | 20篇 |
2017年 | 20篇 |
2016年 | 19篇 |
2015年 | 14篇 |
2014年 | 18篇 |
2013年 | 18篇 |
2012年 | 21篇 |
2011年 | 28篇 |
2010年 | 18篇 |
2009年 | 15篇 |
2008年 | 27篇 |
2007年 | 19篇 |
2006年 | 12篇 |
2005年 | 14篇 |
2004年 | 12篇 |
2003年 | 7篇 |
2002年 | 7篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1996年 | 1篇 |
1994年 | 2篇 |
1987年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有396条查询结果,搜索用时 515 毫秒
131.
The first total synthesis of acetylhomoagmatine, a natural product isolated form the methanolic extracts from the sponge Cliona celata, is performed in four steps in a very high yield. 相似文献
132.
133.
134.
Leonardo Araujo Felipe A. M. F. Pinto Camila C. L. de Andrade Valmir Duarte 《Plant pathology》2022,71(3):654-667
During European canker monitoring in an apple experimental orchard, 14 mummified fruit (two and three trees with 10 and four positive records in 2018 and 2019, respectively) showed perithecia. Perithecium production on apple fruit, confirmation of pathogenicity of Neonectria ditissima isolated from mummified fruit, and ascospore release from fruit tissues has rarely been reported, and their role in the epidemiology of European canker has been largely overlooked. Thus, the objectives of our study were to (a) prove the presence of both conidia and ascospores of N. ditissima in mummified fruit in an experimental field, confirming pathogenesis in different apple cultivars, and (b) monitor production of the two types of inoculum in infected apple fruit over time. Canker incidence in this orchard was 47% of trees with symptoms in 2018 and 48% in 2019. Molecular and morphological tests confirmed that the fungus detected in the mummified apple fruit was N. ditissima. Apple fruit with sporodochia and perithecia washed immediately after collection from the orchard showed conidia but no ascospores of N. ditissima. However, after 4 days’ incubation, perithecia on mummified fruit showed many ascospore cirri. Koch's postulates were fulfilled on apple plants and mature fruit. Fruit inoculated with N. ditissima released spores for over a year under Brazilian field conditions. The release of both spore types peaked in May (Brazilian leaf fall) and October (spring); release of conidia also peaked in February (early harvest). These results support our hypothesis that fruit can serve as primary inoculum for European canker in Brazilian apple orchards. 相似文献
135.
Ezequiel?Grondona Gerardo?Gatti Abel?G.?López Leonardo?Rodolfo?Sánchez Virginia?Rivero Oscar?Pessah María?P.?Zunino Andrés?A.?PonceEmail author 《Plant foods for human nutrition (Dordrecht, Netherlands)》2014,69(4):351-357
The aim of this study was to investigate the bioactivity of the essential oil isolated from Origanum vulgare L. (EOv). We analyzed the in vivo anti-inflammatory properties in a mouse-airway inflammation model and the in vitro antimicrobial activity, genotoxicity over the anaphase-telophase with the Allium cepa strain and its cytotoxicity/viability in A549 culture cells. In vivo, EOv modified the levels of tumor necrosis factor -α and viable activated macrophages and was capable to mitigate the effects of degradation of conjugated dienes. In vitro, EOv reduced the viability of cultured A549 cells as well as the mitotic index and a number of chromosomal aberrations; however, it did not change the number of phases. We found that EOv presents antimicrobial activity against different Gram (?) and (+) strains, measured by disc-diffusion test and confirmed with a more accurate method, the AutoCad software. We postulate that EOv presents antibacterial, antioxidant and chemopreventive properties and could be play an important role as bioprotector agent. 相似文献
136.
Paula Pereira Torga Patr��cia Guimar?es Santos Melo Helton Santos Pereira Luis Cl��udio de Faria Maria Jos�� Del Peloso Leonardo Cunha Melo 《Euphytica》2013,189(2):239-248
The objectives of this study were to assess which environmental factors (local, season or years) are the most important to contribute for the interactions with genotypes of common black beans and to verify the existence of genotypes with broad and/or specific adaptation to the diverse planting seasons in Central Brazil. Data of grain yields for 13 genotypes in 18 field trials used for cultivar registration were utilized, across 2?years (2003 and 2004). Analyses of variance were carried out with decomposition of the genotype x environment interactions. Firstly, data of 18 trials were used, allowing a partial isolation of factors and, subsequently, eight trials were used to allow a complete isolation of the factors. The genotype x sowing seasons (R2?=?4.2?%) and genotype x year (R2?=?4.1?%) interactions were of the greatest important, while genotype x location was less important (R2?=?3.0?%). It was concluded that is more important to conduct evaluations of genotypes in different seasons and years rather than in different locations. The majority of the genotypes tested presented specific adaptation, although it was possible to identify superior lines with wide adaptation. 相似文献
137.
138.
Bruno B. Cunha Wander Gustavo Botero Luciana Camargo Oliveira Viviane M. Carlos Marcelo L. M. Pompêo Leonardo F. Fraceto André H. Rosa 《Water, air, and soil pollution》2012,223(1):329-336
The sorption of four endocrine disruptors, bisphenol A (BPA), estrone (E1), 17β-estradiol (E2), and 17α-ethinylestradiol (EE2)
in tropical sediment samples was studied in batch mode under different conditions of pH, time, and sediment amount. Data obtained
from sorption experiments using the endocrine disruptors (EDs) and sediments containing different amounts of organic matter
showed that there was a greater interaction between the EDs and organic matter (OM) present in the sediment, particularly
at lower pH values. The pseudosecond order kinetics model successfully explained the interaction between the EDs and the sediment
samples. The theoretical and experimentally obtained q
e values were similar, and k values were smaller for higher SOM contents. The k
F values, obtained from the Freundlich isotherms, varied in the ranges 4.2–7.4 × 10−2 (higher OM sediment sample, S2) and 1.7 × 10−3–3.1 × 10−2 (lower OM sediment sample, S1), the latter case indicating an interaction with the sediment that increased in the order: EE2 > > E2 > E1 > BPA. These results
demonstrate that the availability of endocrine disruptors may be directly related to the presence of organic material in sediment
samples. Studies of this kind provide an important means of understanding the mobility, transport, and/or reactivity of this
type of emergent contaminant in aquatic systems. 相似文献
139.
Muhammad Bilal Leonardo Vieira Nunes Marco Thúlio Saviatto Duarte Luiz Fernando Romanholo Ferreira Renato Nery Soriano Hafiz M. N. Iqbal 《Marine drugs》2021,19(4)
Naturally occurring biological entities with extractable and tunable structural and functional characteristics, along with therapeutic attributes, are of supreme interest for strengthening the twenty-first-century biomedical settings. Irrespective of ongoing technological and clinical advancement, traditional medicinal practices to address and manage inflammatory bowel disease (IBD) are inefficient and the effect of the administered therapeutic cues is limited. The reasonable immune response or invasion should also be circumvented for successful clinical translation of engineered cues as highly efficient and robust bioactive entities. In this context, research is underway worldwide, and researchers have redirected or regained their interests in valorizing the naturally occurring biological entities/resources, for example, algal biome so-called “treasure of untouched or underexploited sources”. Algal biome from the marine environment is an immense source of excellence that has also been demonstrated as a source of bioactive compounds with unique chemical, structural, and functional features. Moreover, the molecular modeling and synthesis of new drugs based on marine-derived therapeutic and biological cues can show greater efficacy and specificity for the therapeutics. Herein, an effort has been made to cover the existing literature gap on the exploitation of naturally occurring biological entities/resources to address and efficiently manage IBD. Following a brief background study, a focus was given to design characteristics, performance evaluation of engineered cues, and point-of-care IBD therapeutics of diverse bioactive compounds from the algal biome. Noteworthy potentialities of marine-derived biologically active compounds have also been spotlighted to underlying the impact role of bio-active elements with the related pathways. The current review is also focused on the applied standpoint and clinical translation of marine-derived bioactive compounds. Furthermore, a detailed overview of clinical applications and future perspectives are also given in this review. 相似文献
140.
Eduardo Segundo María P. Carmona Elisa Sáez Leonardo Velasco Germán Martín Leticia Ruiz Dirk Janssen Isabel M. Cuadrado 《European journal of plant pathology / European Foundation for Plant Pathology》2008,122(4):579-591
A study was conducted to determine the identity and prevalence of viruses in 455 greenhouses in the main Spanish green bean
growing area. Directed surveys were conducted in 422 crops from 2000–2004 to collect samples from diseased plants displaying
symptoms that could be attributed to viruses. The samples were analysed to detect any virus by means of dsRNA extraction,
mechanical inoculation to test plants, as well as ELISA and/or RT-PCR tests to detect potyviruses, geminiviruses and viruses
previously known to infect beans in Spain. Random surveys were conducted in the years 2002 and 2005 (in 21 and 12 greenhouses,
respectively) to study the actual incidence of known viruses in the area. Symptoms were recorded in 23,108 plants from which
664 plants were collected and analysed by ELISA or RT-PCR. The results of the directed surveys showed that all the analyzed
crops carried the cryptic virus Phaseolus vulgaris endornavirus (PVuV), whereas phytopathogenic viruses appeared in smaller percentages of the crops: Tomato yellow leaf curl virus (TYLCV) 20.4%, Southern bean mosaic virus (SBMV) 9.0%, Tomato spotted wilt virus (TSWV) 4.0%, and the new species Bean yellow disorder virus (BnYDV) that broke out in 2004 with occurrence values higher than 34.3% that year. From 2000–2004 an important decrease in
TYLCV was observed, along with a slight increase in SBMV and a consistently low occurrence of TSWV. The results of the random
surveys confirmed the increased occurrence of virus detected during the directed surveys, and furthermore demonstrated the
percentage of incidence for each virus. 相似文献