全文获取类型
收费全文 | 192篇 |
免费 | 12篇 |
专业分类
林业 | 20篇 |
农学 | 3篇 |
基础科学 | 4篇 |
82篇 | |
综合类 | 10篇 |
农作物 | 10篇 |
水产渔业 | 8篇 |
畜牧兽医 | 34篇 |
园艺 | 5篇 |
植物保护 | 28篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 3篇 |
2020年 | 8篇 |
2019年 | 11篇 |
2018年 | 9篇 |
2017年 | 7篇 |
2016年 | 11篇 |
2015年 | 5篇 |
2014年 | 3篇 |
2013年 | 10篇 |
2012年 | 11篇 |
2011年 | 11篇 |
2010年 | 7篇 |
2009年 | 3篇 |
2008年 | 17篇 |
2007年 | 13篇 |
2006年 | 9篇 |
2005年 | 12篇 |
2004年 | 15篇 |
2003年 | 10篇 |
2002年 | 8篇 |
2001年 | 2篇 |
1997年 | 3篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有204条查询结果,搜索用时 31 毫秒
101.
102.
Giampieri F Alvarez-Suarez JM Tulipani S Gonzàles-Paramàs AM Santos-Buelga C Bompadre S Quiles JL Mezzetti B Battino M 《Journal of agricultural and food chemistry》2012,60(9):2322-2327
Exposure to UV-A radiation is known to induce discrete lesions in DNA and the generation of free radicals that lead to a wide array of skin diseases. Strawberry (Fragaria × ananassa) contains several polyphenols with strong antioxidant and anti-inflammatory activities. Because the major representative components of strawberry are anthocyanins, these may significantly contribute to its properties. To test this hypothesis, methanolic extracts from the Sveva cultivar were analyzed for anthocyanin content and for their ability to protect human dermal fibroblasts against UV-A radiation, as assayed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenytetrazolium bromide and Comet assays. Five anthocyanin pigments were identified using high-performance liquid chromatography-diode array detection-electrospray ionization/mass spectrometry. Moreover, the strawberry extract showed a photoprotective activity in fibroblasts exposed to UV-A radiation, increasing cellular viability, and diminishing DNA damage, as compared to control cells. Overall, our data show that strawberry contains compounds that confer photoprotective activity in human cell lines and may protect skin against the adverse effects of UV-A radiation. 相似文献
103.
The prevailing paradigm states that cancer cells acquire multiple genetic mutations in oncogenes or tumor suppressor genes whose respective activation/up-regulation or loss of function serve to impart aberrant properties, such as hyperproliferation or inhibition of cell death. However, a tumor is now considered as an organ-like structure, a complex system composed of multiple cell types (e.g., tumor cells, inflammatory cells, endothelial cells, fibroblasts, etc.) all embedded in an inflammatory stroma. All these components influence each other in a complex and dynamic cross-talk, leading to tumor cell survival and progression. As the microenvironment has such a crucial role in tumor pathophysiology, it represents an attractive target for cancer therapy. In this review, we describe the mechanism of action of trabectedin and plitidepsin as an example of how these specific drugs of marine origin elicit their antitumor activity not only by targeting tumor cells but also the tumor microenvironment. 相似文献
104.
Evidente A Andolfi A Cimmino A Vurro M Fracchiolla M Charudattan R 《Journal of agricultural and food chemistry》2006,54(5):1779-1783
Drechslera gigantea, a potential mycoherbicide of grass weeds, was isolated in Florida from naturally infected large crabgrass (Digitaria sanguinalis); it produces phytotoxic metabolites in liquid culture. The main metabolite was identified by spectroscopic methods and optical properties as ophiobolin A (1), a well-known phytotoxic sesterterpene produced by several phytopathogenic fungi of important crops and already extensively studied for its interesting biological activities. The other three minor metabolites proved to be related to ophiobolin A and were identified using the same techniques as 6-epi-ophiobolin A and 3-anhydro-6-epi-ophiobolin A (2 and 3) and ophiobolin I (4). Assayed on punctured detached leaves of several grass and dicotyledon weeds, ophiobolin A proved to be on average more phytotoxic as compared to the other related compounds. Some structural features appear to be important for the phytoxicity, such as the hydroxy group at C-3, the stereochemistry at C-6, and the aldehyde group at C-7. Furthermore, grass weeds usually proved to be more sensitive to the phytotoxins than dicotyledons, on which ophiobolin A caused the appearance of large necrosis even at the lowest concentration assayed. This is the first report about the production of ophiobolins from D. gigantea and of the proposed use as potential natural herbicides against grass weeds. 相似文献
105.
Servili M Settanni L Veneziani G Esposto S Massitti O Taticchi A Urbani S Montedoro GF Corsetti A 《Journal of agricultural and food chemistry》2006,54(11):3869-3875
Fifty lactobacilli isolated from black table olive brines were evaluated for their salt tolerance, resistance to oleuropein and verbascoside, and ability to grow in modified filter-sterilized brines. A strain of Lactobacillus pentosus was selected and used as a starter to ferment, in pilot plant, black olives (Itrana and Leccino cv.) in brines modified for pH, carbohydrate, and growth factor concentrations, at 28 degrees C. The temperature-controlled fermentation of Leccino cv. olives resulted in obtaining ready-to-eat, high-quality table olives in a reduced-time process. HPLC analysis of phenolic compounds from fermented olives showed a decrease of oleuropein, a glucoside secoiridoid responsible for the bitter taste of olive drupes, and an increase of the hydroxytyrosol concentration. The selected strain of L. pentosus (1MO) allowed the reduction of the debittering phase period to 8 days. 相似文献
106.
Servili M Selvaggini R Taticchi A Esposto S Montedoro G 《Journal of agricultural and food chemistry》2003,51(27):7980-7988
The operative conditions of malaxation such as temperature and time of exposure of olive pastes to air contact (TEOPAC) affect volatile and phenolic composition of virgin olive oil (VOO) and, as a consequence, its sensory and healthy qualities. In this paper, optimal temperature and TEOPAC during malaxation were studied, in lab scale, in two Italian cultivars using phenolic compounds, volatile composition, and sensory analysis of VOO as markers. The optimal temperature and TEOPAC, selected by response surface modeling,were cultivar-dependent being 30 min of TEOPAC at the lowest temperature investigated (22 degrees C) and 0 min of TEOPAC at 26 degrees C for Frantoio and Moraiolo cultivars, respectively. 相似文献
107.
Vicentini CB Mares D Tartari A Manfrini M Forlani G 《Journal of agricultural and food chemistry》2004,52(7):1898-1906
Two series of new pyrazoles, namely six pyrazolo[1,5-a][1,3,5]triazine-2,4-dione and four pyrazolo[1,5-c][1,3,5]thiadiazine-2-one derivatives, were synthesized as potential inhibitors of the photosynthetic electron transport chain at the photosystem II level. The compounds were confirmed by 1H NMR, elemental, and IR analyses. Their biological activity was evaluated in vivo upon both the growth of blue-green algae and the photosynthetic oxygen evolution by eukaryotic algae and in vitro as the ability to interfere with light-driven reduction of ferricyanide by isolated spinach chloroplasts. Some compounds exhibited remarkable inhibitory properties, comparable to those of the reference commercial herbicides lenacil, diuron, and hexazinone. Results suggest that the substitution of triazine with thiadiazine ring may act as amplifier for herbicidal activity. 相似文献
108.
Rosselli S Maggio A Piozzi F Simmonds MS Bruno M 《Journal of agricultural and food chemistry》2004,52(26):7867-7871
Two known neo-clerodane diterpenoids, scutecyprol A (1) and scutalbin C (2), have been isolated from the acetone extract of the aerial parts of Scutellaria sieberi. The antifeedant activity of scutecyprol A (1), of its 15-oxo derivative (3), and of several halohydrins (4-9), synthesized starting from compounds 1 and 3, against Spodoptera littoralis have been determined and structure-antifeedant relationships are discussed. 相似文献
109.
Maurizio Rossetto 《Biological conservation》2005,121(1):35-43
Hybridization plays an important role in the evolution of plant diversity. Nonetheless, it is often difficult to clearly ascertain hybrid origin by assessing morphological characters alone. Acronychia littoralis (Rutaceae) is a recently described rare tree from littoral rainforests in eastern Australia. Two forms have been tentatively distinguished on the basis of different leaf morphology however, because of the variability of the discriminatory characters across populations (and in some cases across single individuals), compiling data on the exact distribution of each form has been a difficult process. To further complicate matters, some of these distinguishing morphological characters are intermediate between those of closely related, sympatric species. As a result, simple molecular techniques were developed to assist the development of adequate conservation and management strategies for A. littoralis and to better understand its evolutionary history. Sequence data from the ITS2 region were obtained and haplotype specific primers that distinguished the two forms and the related taxa were developed. Sequence data suggest that the two forms of A. littoralis are each of hybrid origin but both involve different parental taxa. The findings provide a perspective on the evolutionary dynamics of the local rainforest flora and highlight the need for phylogenetic evaluation of rare taxa where there is taxonomic ambiguity. 相似文献
110.
The feeding preference of the collembolan Protaphorura armata in the presence of Fusarium culmorum and Gaeumannomyces graminis var. tritici, two soil-borne fungi pathogenic for winter cereals, was studied in a simplified experimental system including wheat seedlings. Analysis of gut content of all animals from microcosms containing inoculum of both fungi showed that F. culmorum was clearly preferred but that G. graminis var. tritici was also fed. At microscopic examination the majority of F. culmorum conidia present in the gut lacked cytoplasmic content, and only few conidial cells were intact. The feeding preference of P. armata favoured G. graminis var. tritici over F. culmorum in the competition for infection sites on wheat plants; in fact, the former resulted the prevalent cause of plant disease.
The viability of fungal propagules after passage through the gut of P. armata was also studied. No colonies of G. graminis var. tritici and only a few colonies of F. culmorum developed from faecal pellets set on agar medium. Fungal propagules dispersed by springtails were not sufficient to induce disease, as demonstrated by introducing animals, previously fed on fungal cultures separately, into microcosms containing a sterile substrate where wheat kernels were seeded. 相似文献