全文获取类型
收费全文 | 160篇 |
免费 | 9篇 |
专业分类
林业 | 14篇 |
农学 | 3篇 |
33篇 | |
综合类 | 23篇 |
农作物 | 14篇 |
水产渔业 | 2篇 |
畜牧兽医 | 70篇 |
园艺 | 1篇 |
植物保护 | 9篇 |
出版年
2024年 | 1篇 |
2022年 | 2篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 4篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 8篇 |
2013年 | 9篇 |
2012年 | 11篇 |
2011年 | 11篇 |
2010年 | 8篇 |
2009年 | 6篇 |
2008年 | 12篇 |
2007年 | 8篇 |
2006年 | 14篇 |
2005年 | 9篇 |
2004年 | 13篇 |
2003年 | 7篇 |
2002年 | 8篇 |
2001年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1993年 | 1篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 3篇 |
1983年 | 1篇 |
排序方式: 共有169条查询结果,搜索用时 15 毫秒
61.
Strålsjö LM Witthöft CM Sjöholm IM Jägerstad MI 《Journal of agricultural and food chemistry》2003,51(1):128-133
Folate concentrations in strawberries and folate retention during storage and commercial processing of strawberries were investigated. No previous study has focused on the effects of cultivar, ripeness, and year of harvest of strawberries with respect to the folate content. This study showed the folate concentration in strawberries to significantly depend on all of these different factors. Total folate was quantified using a modified and validated radioprotein-binding assay with external calibration (5-CH(3)-H(4)folate). Folate content in 13 different strawberry cultivars varied from 335 microg/100 g of dry matter (DM) for cv. Senga Sengana to 644 microg/100 g of DM for cv. Elsanta. Swedish harvests from 1999 and 2001 yielded higher folate concentrations than did the harvest from 2000, and the grade of ripeness affected the folate content in strawberries. This study indicated high folate retention in intact berries during storage until 3 or 9 days at 4 degrees C (71-99%) and also in most tested commercial products (79-103%). On the basis of these data fresh strawberries as well as processed strawberry products are recommended to be good folate sources. For instance, 250 g (fresh weight) of strawberries ( approximately 125 microg of folate) supplies approximately 50% of the recommended daily folate intake in various European countries (200-300 microg/day) or 30% of the U.S. recommendation (400 microg/day). 相似文献
62.
Doris Traweger Rita Travnitzky Cornelia Moser Christian Walzer Guenther Bernatzky 《Journal of pest science》2006,79(3):113-125
The population of Rattus norvegicus was assessed using live traps and hair sampling tubes in 71 discrete patches distributed in the urban area of the city of Salzburg, Austria. R. norvegicus occurred in 35% of the examined habitats and reached a maximum density of 113.12 individuals/km along water banks. The occurrence of rats was strongly influenced by vegetation, habitat modification and man-made impact in the area. The results of this study could be used to support the development of a new, more scientifically based rat management plan in cooperation with the city of Salzburg. 相似文献
63.
ABSTRACT The vertical distribution of Pratylenchus penetrans was monitored in four fields cropped with maize, black salsify, carrot, or potato. Soil samples were collected at 21-day intervals from May 2002 until April 2003 from five plots (2 x 5 m(2)) per field. Per plot, 15 cores were taken to a depth of 70 cm and split into seven segments of 10 cm each. Within the plots, segments from corresponding depths were pooled. After mixing, 200-g subsamples were taken and nematodes were extracted by zonal centrifugation from the root fraction and the mineral soil fraction separately. In most crops, the root fraction contained more than 50% of the total number of P. penetrans. Because the ratio between the numbers of nematodes in the root fraction and mineral soil fraction changes during the growing season, numbers of P. penetrans found in the mineral soil fraction cannot be used to estimate the total number in the soil. Therefore, both fractions have to be processed to obtain a reliable estimate of the density. No nematodes were recovered below 50 cm soil depth, except in the maize field where nematodes were found at 70 cm. The optimum sampling depth for maize, black salsify, carrot, and potato was 45, 25, 25, and 35 cm, respectively. The percentage of nematodes per soil layer was independent of the sampling date, indicating that a defined optimum sampling depth will be applicable throughout all seasons. The cumulative vertical distribution, modeled with a logistic equation, can be used to estimate the sampling error when samples are collected at different depths. 相似文献
64.
65.
This review focuses on smart nano-materials built of stimuli-responsive (SR) polymers and will discuss their numerous applications in the biomedical field. The authors will first provide an overview of different stimuli and their corresponding, responsive polymers. By introducing myriad functionalities, SR polymers present a wide range of possibilities in the design of stimuli-responsive devices, making use of virtually all types of polymer constructs, from self-assembled structures (micelles, vesicles) to surfaces (polymer brushes, films) as described in the second section of the review. In the last section of this review the authors report on some of the most promising applications of stimuli-responsive polymers in nanomedicine. In particular, we will discuss applications pertaining to diagnosis, where SR polymers are used to construct sensors capable of selective recognition and quantification of analytes and physical variables, as well as imaging devices. We will also highlight some examples of responsive systems used for therapeutic applications, including smart drug delivery systems (micelles, vesicles, dendrimers...) and surfaces for regenerative medicine. 相似文献
66.
Styer KL Singh V Macosko E Steele SE Bargmann CI Aballay A 《Science (New York, N.Y.)》2008,322(5900):460-464
A large body of evidence indicates that metazoan innate immunity is regulated by the nervous system, but the mechanisms involved in the process and the biological importance of such control remain unclear. We show that a neural circuit involving npr-1, which encodes a G protein-coupled receptor (GPCR) related to mammalian neuropeptide Y receptors, functions to suppress innate immune responses. The immune inhibitory function requires a guanosine 3',5'-monophosphate-gated ion channel encoded by tax-2 and tax-4 as well as the soluble guanylate cyclase GCY-35. Furthermore, we show that npr-1- and gcy-35-expressing sensory neurons actively suppress immune responses of nonneuronal tissues. A full-genome microarray analysis on animals with altered neural function due to mutation in npr-1 shows an enrichment in genes that are markers of innate immune responses, including those regulated by a conserved PMK-1/p38 mitogen-activated protein kinase signaling pathway. These results present evidence that neurons directly control innate immunity in C. elegans, suggesting that GPCRs may participate in neural circuits that receive inputs from either pathogens or infected sites and integrate them to coordinate appropriate immune responses. 相似文献
67.
• Introduction
Commercial thinning (CT) could contribute to increase short-term tree growth and be beneficial in a cold climate, as in boreal regions. Thus, growth rate, ring density and flexural modulus of elasticity (MOE) of trees may change after CT. Moreover, mechanical wood properties vary with position in the tree, and there is a need to develop optimal log allocation strategies in order to allocate logs to their best use. 相似文献68.
Walter W. WENZEL Cornelia MESMER Eric J. FLORIDA Markus PUSCHENREITER Holger KIRCHMANN 《土壤圈》2022,32(4):543-554
Diffusive gradients in thin films (DGT) measurements have been shown to outperform other phosphorus (P) tests in soils with strong P sorption, but this has not been confirmed for moderately weathered European soils. We compared the performance of DGT in predicting wheat grain yield in Swedish long-term fertility experiments with those of standard intensity (water-extractable P (P-H2O)) and quantity (ammonium lactate-extractable P (P-AL)) tests. A Mitscherlich-type model was used to fit wheat yield response to P application rates (0, 15, 30 or 35, and 45 kg P ha-1 year-1) in each individual trial replicate to estimate the maximum yield. For trials with clear plateau-type yield responses and the goodness of fit (R2) > 0.75, relative yields (RYs) were calculated for each P treatment and plotted against the soil P test results (n=143). The goodness of the Mitscherlich-type fits decreased in the following order:DGT-measured P (P-DGT) (R2=0.35) > P-H2O (R2=0.18) > P-AL (R2=0.13). When excluding soils with P-AL:P-DGT ≥ 0.1 L g-1, R2 was considerably improved to 0.55 for P-AL, 0.46 for P-H2O, and 0.65 for P-DGT (n=61). At 95% of maximum yield, the upper limit of P deficiency for P-DGT was 44.8 (the soils with P-AL:P-DGT < 0.1 L g-1) and 61.9 μg L-1 (all soils), falling within the range reported for other European and Australian soils (6.0-142 μg L-1). We show that in the investigated Swedish soils, DGT performed better than the quantity and intensity tests, which is attributed to its ability to capture P diffusion and resupply from the soil solid phase, similar to plant roots in the rhizosphere. 相似文献
69.
Jugl-Chizzola M Spergser J Schilcher F Novak J Bucher A Gabler C Hagmüller W Zitterl-Eglseer K 《Berliner und Münchener tier?rztliche Wochenschrift》2005,118(11-12):495-501
The aim of the study was to test Thymi herba (1.66% v/w essential oil with 39% p-cymene and 32% thymol) in the rearing period of piglets as feed additive. Therefore, two feeding trials were performed with piglet groups ranging from 17 to 22 animals each. Either 10 g of Thymi herba/kg feed (Thymi herba group), 10 mg flavophospholipol/kg feed (flavophospholipol group) or nothing (control group) was added to the animals' feed. No significant differences in the performance parameter daily weight gain among any groups were recorded. No differences concerning feed efficiency or isolation of haemolytic E. coli serotypes were shown. In addition, the antibacterial activity of the essential oil of Thymi herba against 39 haemolytic E. coli isolates from the same weaners was investigated in vitro by disk diffusion, minimum inhibitory concentration and bactericidal concentration testing. In contrast to the feeding results, the essential oil of the thyme batch fed showed antibacterial activity against all haemolytic E. coli investigated. This interesting antibacterial potential of Thymi herba prompts further investigations as to its value as feed additive. 相似文献
70.
Lipophilic and polar extracts of iris rhizomes (Iris germanica) were submitted to a phytochemical profiling by a combination of HPLC–PDA–MS and semi-preparative HPLC/off-line microprobe NMR measurements. A total of 20 compounds were purified in sub-milligram to milligram amounts via two successive chromatographic steps. They were identified as isoflavones, isoflavone glycosides and acetovanillone by analysis of on-line MS and PDA, and off-line NMR data. A new isoflavone glycoside, iriflogenin-4′-O-gentiobioside, was subsequently isolated at preparative scale for full chemical characterization. This study demonstrates the applicability of the HPLC/off-line microprobe NMR approach as a robust means for rapid phytochemical profiling of plant extracts. 相似文献