全文获取类型
收费全文 | 745篇 |
免费 | 34篇 |
专业分类
林业 | 104篇 |
农学 | 23篇 |
基础科学 | 3篇 |
234篇 | |
综合类 | 32篇 |
农作物 | 67篇 |
水产渔业 | 47篇 |
畜牧兽医 | 190篇 |
园艺 | 16篇 |
植物保护 | 63篇 |
出版年
2024年 | 3篇 |
2023年 | 10篇 |
2022年 | 10篇 |
2021年 | 24篇 |
2020年 | 25篇 |
2019年 | 38篇 |
2018年 | 29篇 |
2017年 | 23篇 |
2016年 | 29篇 |
2015年 | 20篇 |
2014年 | 33篇 |
2013年 | 37篇 |
2012年 | 65篇 |
2011年 | 69篇 |
2010年 | 50篇 |
2009年 | 28篇 |
2008年 | 51篇 |
2007年 | 53篇 |
2006年 | 32篇 |
2005年 | 33篇 |
2004年 | 35篇 |
2003年 | 30篇 |
2002年 | 24篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
1974年 | 1篇 |
1972年 | 3篇 |
1971年 | 1篇 |
排序方式: 共有779条查询结果,搜索用时 203 毫秒
771.
Helena Gaspar Sonia Savluchinske Feio Ana Isabel Rodrigues Rob Van Soest 《Marine drugs》2004,2(1):8-13
The antifungal activity of the sesquiterpenoids (+)-curcuphenol and (+)- curcudiol isolated from the Caribbean sponge Didiscus oxeata was evaluated against several filamentous fungi. 相似文献
772.
Summary Tubers showed changes in their nutritional value caused by the treatment of the plants with the insecticide deltamethrin.
The level of starch was increased in comparison with control tubers; but the amylose percentage was not affected. In contrast,
the total protein content decreased in tubers from treated plants, whereas free amino acids level and ascorbic acid content
increased. The results showed that the changes in the tubers caused by the treatment of potato plants with deltamethrin did
not adversely affect the nutritional value of the progeny tubers. 相似文献
773.
Aguilera Y Dueñas M Estrella I Hernández T Benitez V Esteban RM Martín-Cabrejas MA 《Plant foods for human nutrition (Dordrecht, Netherlands)》2011,66(2):187-195
This study presents the effects of soaking, cooking and industrial dehydration on the phenolic profile, and antioxidant capacity
in two chickpea varieties (Sinaloa and Castellano). Chromatographic analysis identified a total of 24 phenolic components,
being isoflavones the main phenolics in raw and processed Sinaloa and Castellano flours. The impact of the industrial dehydration
was different depending on the chickpea variety. Although Castellano chickpea exhibited the highest levels of phenolic compounds
(103.1 μg/g), significant reductions were observed during processing; in contrast, the dehydration did not cause any further
effects in Sinaloa flours. Interestingly, Sinaloa variety showed high thermal stability of isoflavones during processing.
As expected, the levels of antioxidant capacity were in accordance with the behavior of phenolic compounds exhibiting noticeable
reductions in Castellano chickpea and not relevant changes in Sinaloa chickpea. Thus, the significant occurrence of bioactive
phenolic compounds along with the relevant antioxidant capacities of dehydrated chickpea flours make them to be considered
functional ingredients for their beneficial health effects, especially in case of Sinaloa. 相似文献
774.
Tea is a popular beverage whose consumption is associated with prevention of certain disorders. The objective of the study
was to investigate the potential neuroprotective effect of white tea extract (WTE) on hydrogen peroxide induced toxicity in
PC12 cells. Cells were treated with various doses of WTE (10–250 μg/ml) before exposition to 250 μM hydrogen peroxide and
cell survival was determined through the MTT and LDH assays. Oxidative stress was quantified in the cells after treatments
as intracellular reactive oxygen species (ROS) production and the antioxidant activity of the extract was assessed in a cell
free system in terms of free radical scavenging capacity. Results showed that WTE has a significant protective effect in the
PC12 cell line against hydrogen peroxide as cell survival was significantly superior in WTE-treated cells compared to hydrogen
peroxide-treated cells. A reduction on intracellular oxidative stress as well as radical scavenging properties were produced
by WTE. Results suggest that WTE protects PC12 cells against H2O2-induced toxicity, and that an antioxidant mechanism through ROS scavenging may be in part responsible for cells neuroprotection. 相似文献
775.
【目的】明确环斑猛猎蝽(Sphedanolestes impressicollis Stal.)对烟田烟蚜[Myzus persicae(Sulzer)]若虫的捕食潜力,为田间应用环斑猛猎蝽防控烟蚜提供参考。【方法】实验室条件下,在培养皿中设置1头饥饿24 h的环斑猛猎蝽4龄若虫与不同密度梯度的1~4龄烟蚜若虫,统计环斑猛猎蝽的捕食量并通过GrapPad Prism 8.0、DPS等软件进行生物学统计分析,明确环斑猛猎蝽对烟蚜若虫的功能反应和搜寻效应;以不同密度的环斑猛猎蝽4龄若虫与烟蚜4龄若虫在不同温度梯度及空间格局条件下,通过控制单一变量法并构建线性回归方程,明确环斑猛猎蝽4龄若虫种内干扰对捕食率的影响以及自身密度、温度、空间格局对捕食量的影响,评估环斑猛猎蝽4龄若虫对烟蚜4龄若虫的捕食功能反应模型。【结果】环斑猛猎蝽4龄若虫对烟蚜若虫的捕食功能反应符合Holling-II模型,其种内干扰及自身密度对捕食量的影响分别符合Hassell模型和Watt模型。环斑猛猎蝽4龄若虫对1~4龄烟蚜若虫中的3龄和4龄若虫捕食具有偏好性,对4龄若虫的捕食量最大,最大日捕食量为55.7头,其次为3龄烟蚜(55.3头)。在空间一定和烟蚜若虫定量条件下,环斑猛猎蝽4龄若虫个体间存在种内干扰,干扰系数为1.31,并随着自身密度的增加干扰增强,平均捕食量下降。在不同空间且烟蚜若虫密度一定的条件下,随着空间的增大,环斑猛猎蝽4龄若虫对猎物的捕食量减少。在16~32℃的温度梯度下,环斑猛猎蝽4龄若虫对烟蚜若虫的捕食量随着温度的升高而逐渐增强,32℃下的日捕食量最大,达23头。【结论】环斑猛猎蝽在烟田中具有防治烟蚜的潜力。 相似文献
776.
Juan Vera Isabel Abrisqueta José M. Abrisqueta M. C. Ruiz-Sánchez 《Irrigation Science》2013,31(4):747-757
The effects of different deficit-irrigation strategies on plant-water status and yield were studied for 5 years in early-maturing peach trees (cv. Flordastar) growing under Mediterranean climatic conditions. The deficit-irrigation (DI) treatments were continuous, regulated (RDI), partial root-zone drying and a soil water content-based treatment. Peach fruit yield was more affected by post-harvest irrigation than by pre-harvest irrigation. Deficit irrigation for this cultivar produced significant water savings but caused a yield penalty, with the RDI treatment showing the clearest manifestation of this. Deficit irrigation in general affected the number of fruits per tree more than fruit size. Average stem water potential threshold values for summer (July–August–September) should be maintained above ?0.9 MPa if yields are not to decrease by more than 10 %. The marginal water use efficiency value of 0.07 for the irrigation range studied indicates that the maximum benefit, derived from a linear production function, will always occur at the limit of the water constraint prior to maximum yield values. Decision-makers should apply the minimal amount of irrigation water that allows maximum yields. Since DI treatments decrease yield due to smaller tree sizes, it is advisable that thinning practices be adapted when deficit irrigation is imposed. 相似文献
777.
Gonzalez-Saiz JM Pizarro C Esteban-Díez I Ramírez O Gonzalez-Navarro CJ Saiz-Abajo MJ Itoiz R 《Journal of agricultural and food chemistry》2007,55(8):2930-2936
The valorization of vegetable byproducts is one of the main objectives of industry today. The project on which this study is based examined the potential usefulness of worthless onions (Allium cepa L. sp.) and overproduction to obtain several functional products with different applications in the food industry. Near-infrared (NIR) spectroscopy, combined with multivariate calibration, has been used to monitor the alcoholic fermentation of onion juice. Good results were obtained, revealing the suitability of NIR spectroscopy for controlling and optimizing this process in real time. 相似文献
778.
María Victoria Vadell Carlos González Fischer Mariano Codesido Aníbal Carbajo David Bilenca Isabel E. Gómez Villafañe 《Zoonoses and public health》2023,70(1):13-21
Hantavirus pulmonary syndrome (HPS) is a zoonotic emerging infectious disease caused by New World orthohantaviruses (family Hantaviridae) hosted by rodents of the family Cricetidae. In Argentina, one of its main hosts is the sigmodontine rodent Oligoryzomys flavescens, a widely distributed mouse of the Pampas, Delta and Espinal ecoregions of central-east Argentina. Because the abundance of the reservoir and its proportion in the rodent community affects both virus prevalence and human exposure risk, its estimation throughout its known geographical distribution is of key importance for the design of public health strategies to prevent HPS. The aim of this study was therefore to model the relative abundance of O. flavescens in most of the Pampas ecoregion within Buenos Aires Province, Argentina, where hantavirus pulmonary syndrome is endemic. To do this we used owl-pellet samples collected between 2006 and 2008 from 51 sites distributed throughout most of Buenos Aires province. Mammalian prey in each pellet was identified to the lowest possible taxonomic level by examination of the skulls, dentaries and molars. We modelled the frequency of O. flavescens found in each sample as a function of climatic, environmental, and topographic data of each site. The two best models were applied to a Geo referential Information System to build maps of estimated frequency (as a proxy of relative abundance) within Buenos Aires province. Estimated relative abundance of O. flavescens in Buenos Aires province was significantly associated with annual mean temperature, annual precipitation and presence of freshwater bodies, and varied among sub-regions, with the Inland and Rolling Pampas being the regions with highest frequencies. Knowing in which areas O. flavescens abundance is expected to be higher can be used to concentrate limited sanitary efforts in those areas that are most needed in order to reduce transmission and increase detection. 相似文献
779.
The proteolytic activities during rye (Secale cereale L. ‘Humbolt’) grain germination were monitored using in‐solution methods and one‐ and two‐dimensional PAGE with gels that contained incorporated substrate proteins. The total proteolytic activity increased during the first three days of germination, but not after that. The proteinase activity was measured at pH 3.8, 6.0, and 8.0 in the presence and absence of class‐specific proteinase inhibitors. This indicated that enzymes from all four proteinase classes were present during the germination process. Germinated rye grain contained mainly aspartic and cysteine proteinase activities that are especially active at pH 3.8. Serine‐ and metallo‐proteinases were less abundant. Overall, the pattern of hydrolysis was very similar to that observed during barley and wheat germination. 相似文献