全文获取类型
收费全文 | 440篇 |
免费 | 35篇 |
专业分类
林业 | 20篇 |
农学 | 15篇 |
基础科学 | 2篇 |
72篇 | |
综合类 | 49篇 |
农作物 | 24篇 |
水产渔业 | 20篇 |
畜牧兽医 | 224篇 |
园艺 | 9篇 |
植物保护 | 40篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 6篇 |
2021年 | 22篇 |
2020年 | 23篇 |
2019年 | 17篇 |
2018年 | 12篇 |
2017年 | 20篇 |
2016年 | 18篇 |
2015年 | 11篇 |
2014年 | 14篇 |
2013年 | 16篇 |
2012年 | 33篇 |
2011年 | 38篇 |
2010年 | 26篇 |
2009年 | 17篇 |
2008年 | 35篇 |
2007年 | 22篇 |
2006年 | 22篇 |
2005年 | 21篇 |
2004年 | 21篇 |
2003年 | 14篇 |
2002年 | 19篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 3篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1969年 | 1篇 |
1965年 | 1篇 |
1960年 | 1篇 |
排序方式: 共有475条查询结果,搜索用时 0 毫秒
21.
A new acylated quercetin glycoside, quercetin 3-O-(2-t-p-coumaroyl)-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside-7-O-beta-D-glucopyranoside (1), together with the known 3-(3,4-dihydroxyphenyl)lactic acid (2) were isolated from Ranunculus lanuginosus leaves and identified on the basis of detailed spectral analysis, including 2D-NMR spectrometry and ESI-MS. 相似文献
22.
Alison Burrells Julio Benavides German Cantón Jo?o L Garcia Paul M Bartley Mintu Nath Jackie Thomson Francesca Chianini Elisabeth A Innes Frank Katzer 《Veterinary research》2015,46(1)
As clinical toxoplasmosis is not considered a problem in pigs, the main reason to implement a control strategy against Toxoplasma gondii (T. gondii) in this species is to reduce the establishment of T. gondii tissue cysts in pork, consequently reducing the risk of the parasite entering the human food chain. Consumption of T. gondii tissue cysts from raw or undercooked meat is one of the main sources of human infection, with infected pork being considered a high risk. This study incorporates a mouse bioassay with molecular detection of T. gondii DNA to study the effectiveness of vaccination (incomplete S48 strain) in its ability to reduce tissue cyst burden in pigs, following oocyst (M4 strain) challenge. Results from the mouse bioassay show that 100% of mice which had received porcine tissues from vaccinated and challenged pigs survived compared with 51.1% of mice which received tissues from non-vaccinated and challenged pigs. The presence (or absence) of T. gondii DNA from individual mouse brains also confirmed these results. This indicates a reduction in viable T. gondii tissue cysts within tissues from pigs which have been previously vaccinated with the S48 strain. In addition, the study demonstrated that the main predilection sites for the parasite were found to be brain and highly vascular muscles (such as tongue, diaphragm, heart and masseter) of pigs, while meat cuts used as human food such as chop, loin, left tricep and left semitendinosus, had a lower burden of T. gondii tissue cysts. These promising results highlight the potential of S48 strain tachyzoites for reducing the number of T. gondii tissues cysts in pork and thus improving food safety. 相似文献
23.
Quayle WC Oliver DP Zrna S Fattore A 《Journal of agricultural and food chemistry》2007,55(13):5199-5204
The fate of benzofenap [2-[4-(2,4-dicholoro-m-toluoyl)-1,3-dimethylpyrazol-5-yloxy]-4'-methylacetophenone] applied to flooded rice was studied at two locations in New South Wales (Australia). Solid-phase extraction (SPE) was compared with liquid-liquid extraction (LLE) for the determination of the commercial chemical in water samples. SPE performed well as compared to LLE (84 vs 80%) in irrigation waters. However, at the lower end of the concentration range (3 microg/L), LLE achieved higher recoveries than SPE (72 vs 59%). Rates of dissipation (DT50) from floodwaters and soils were measured. Dissipation of the herbicide from water and soil occurred fairly erratically in both mediums and can be best explained by a first-order decay process. The DT50 value for benzofenap was <1 day in irrigation water due to rapid deposition of the suspension concentrate formulation. The DT50 in surface soil was 44 days. The maximum measured concentration of benzofenap in a rice field floodwater was 39 microg/L, taking approximately 32 days to dissipate to <1 microg/L. 相似文献
24.
Bryszewska MA Ambroziak W Langford NJ Baxter MJ Colyer A Lewis DJ 《Plant foods for human nutrition (Dordrecht, Netherlands)》2007,62(3):121-126
The potential of selenium-enriched rye/wheat sourdough bread as a route for supplementing dietary selenium intakes is reported.
In addition to their normal diets, 24 female volunteers (24 to 25 years old) were fed either selenium-enriched bread or non-enriched
bread each day (68.02 and 0.84 μg selenium day−1 respectively) for 4 weeks. The chemical form of the selenium in the bread had been characterised using HPLC-ICP-MS, which
showed that 42% of the extractable selenium was present as selenomethionine. Plasma selenium levels and plasma platelet glutathione
peroxidase (GPx1) activity were measured in the volunteers’ blood over a 6-week period. A statistically significant difference
(p = 0.001) was observed in the mean percentage change data, calculated from the plasma selenium level measurements for the
enriched and control group, over the duration of the study. A comparable difference was not observed for the platelet GPx1
activity (p = 0.756), over the same period. Two weeks after cessation of the feeding stage, i.e., at t = 6 weeks, the mean percentage change value for the selenium plasma levels in the enriched group was still significantly
elevated, suggesting that the absorbed selenium had been incorporated into the body’s selenium reserves, and was then being
slowly released back into the volunteers’ blood. 相似文献
25.
Hennessy Louise M. Popay Alison J. Glare Travis R. Finch Sarah C. Cave Vanessa M. Rosts Michael 《Journal of pest science》2022,95(1):263-277
Journal of Pest Science - Argentine stem weevil adults (ASW, Listronotus bonariensis) feed on the leaves of agricultural grasses and their larvae mine the pseudostem, causing extensive damage that... 相似文献
26.
Tom MISSELBROOK Zhaohai BAI Zejiang CAI Weidong CAO Alison CARSWELL Nicholas COWAN Zhenling CUI David CHADWICK Bridget EMMETT Keith GOULDING Rui JIANG Davey JONES Xiaotang JU Hongbin LIU Yuelai LU Lin MA David POWLSON Robert M. REES Ute SKIBA Pete SMITH Roger SYLVESTER-BRADLEY John WILLIAMS Lianhai WU Minggang XU Wen XU Fusuo ZHANG Junling ZHANG Jianbin ZHOU Xuejun LIU 《农业科学与工程前沿(英文版)》2022,9(3):475
27.
Planting stock selection is an integral part of plantation management, as forest nursery practices influence the physiological status of the seedlings and their capacity to cope with resource availability on different planting sites. We thus compared the 11th-year dimensions and survival of large white spruce (Picea glauca) and black spruce (P. mariana) seedlings produced as 2 + 2 bareroot or 2 + 0 container stock (cell volume of 350 cm3), used to reduce the need for competition control. Using complete split-block designs, we evaluated the seedling competitive potential and response to mechanical release on two sites of contrasting ecological fertility and vegetation dominance in Quebec, Canada. We found that large spruce seedlings can be successfully established on high-competition sites in a context where chemical herbicides cannot be used. These stock types had a limited impact on survival and growth, and both stock responded similarly to mechanical vegetation control. In this context, the choice of stock type should prioritize the highest quality large seedling based on operational considerations such as availability and ease of transportation. Mechanical site preparation was not necessary to promote seedling growth and survival on these sub-boreal sites. 相似文献
28.
Jacqueline M. Bishop Alison J. Leslie Sven L. Bourquin Colleen ORyan 《Biological conservation》2009,142(10):2335-2341
Unchecked exploitation of wildlife resources is one of the major factors influencing species persistence throughout the world today. A significant consequence of exploitation is the increasing rate at which genetic diversity is lost as populations decline. Recent studies suggest that life history traits affecting population growth, particularly in long-lived species, may act to moderate the impact of population decline on genetic variation and lead to remnant populations that appear genetically diverse despite having passed through substantial demographic bottlenecks. In this study we show that the retention of genetic variation in a partially recovered population of Nile crocodile is deceptive, as it masks the reality of a significant decline in the population’s effective size (Ne). Repeated episodes of unchecked hunting in the mid to late 20th century have today led to a five-fold decrease in the population’s Ne. Using current census data we estimate the contemporary Ne/N ratio as 0.05 and, in light of quotas that permit the ongoing removal of adults, simulated the likely effects of genetic drift on extant levels of variation. Results indicate that even if the current effective size is maintained, both allelic diversity and heterozygosity will decline. Our findings have complex implications for long-lived species; an emphasis on the retention of genetic variation alone, whilst disregarding the effects of population decline on effective size, may ultimately obscure the continued decline and extinction of exploited populations. 相似文献
29.
Humbles AA Lloyd CM McMillan SJ Friend DS Xanthou G McKenna EE Ghiran S Gerard NP Yu C Orkin SH Gerard C 《Science (New York, N.Y.)》2004,305(5691):1776-1779
Features of chronic asthma include airway hyperresponsiveness, inflammatory infiltrates, and structural changes in the airways, termed remodeling. The contribution of eosinophils, cells associated with asthma and allergy, remains to be established. We show that in mice with a total ablation of the eosinophil lineage, increases in airway hyperresponsiveness and mucus secretion were similar to those observed in wild-type mice, but eosinophil-deficient mice were significantly protected from peribronchiolar collagen deposition and increases in airway smooth muscle. These data suggest that eosinophils contribute substantially to airway remodeling but are not obligatory for allergen-induced lung dysfunction, and support an important role for eosinophil-targeted therapies in chronic asthma. 相似文献
30.
John M Kreeger Alison Templer Susan E Tumquist Keith L Bailey Philip J Johnson David A Wilson 《Journal of veterinary diagnostic investigation》2002,14(4):322-325
Paranasal meningioma was diagnosed in a 5-year-old Appaloosa gelding. The mass occupied the right maxillary, frontal, and sphenopalatine sinuses but did not invade the calvarium. The diagnosis was based on histologic evaluation, positive immunohistochemical staining for vimentin and cytokeratin, and ultrastructural features including the presence of interdigitating spindle cells with numerous desmosomes. 相似文献