全文获取类型
收费全文 | 356篇 |
免费 | 15篇 |
国内免费 | 1篇 |
专业分类
林业 | 20篇 |
农学 | 6篇 |
基础科学 | 1篇 |
81篇 | |
综合类 | 36篇 |
农作物 | 6篇 |
水产渔业 | 22篇 |
畜牧兽医 | 189篇 |
园艺 | 5篇 |
植物保护 | 6篇 |
出版年
2023年 | 1篇 |
2021年 | 3篇 |
2020年 | 3篇 |
2019年 | 7篇 |
2018年 | 11篇 |
2017年 | 12篇 |
2016年 | 8篇 |
2015年 | 9篇 |
2014年 | 3篇 |
2013年 | 26篇 |
2012年 | 26篇 |
2011年 | 25篇 |
2010年 | 15篇 |
2009年 | 15篇 |
2008年 | 30篇 |
2007年 | 25篇 |
2006年 | 27篇 |
2005年 | 26篇 |
2004年 | 22篇 |
2003年 | 26篇 |
2002年 | 21篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1984年 | 1篇 |
1980年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有372条查询结果,搜索用时 15 毫秒
21.
Whent M Ping T Kenworthy W Yu LL 《Journal of agricultural and food chemistry》2010,58(24):12602-12607
A high-throughput assay was developed to detect soybean lipoxygenase 1 (LOX-1) using a multilabel plate reader. The assay was also adapted to a single cell fluorometer. Fluorescein is degraded by linoleic hydroperoxide produced from soybean lipoxygenase and linoleic acid. The decrease in fluorescence is measured over time, and the area-under-the-curve (AUC) is used to quantify the LOX-1 content of soybean extract. A dose-dependent response is seen with varied dilutions of pure LOX enzyme or soybean extracts. Percent recovery was between 97% and 108%, and relative standard deviation was 4.3%. Advantages of the assay include the reduced preparation time of samples and reduced use of reagents in the high-throughput assay. Multiple samples can be measured in a single run with a multilabel plate reader. 相似文献
22.
23.
Tony H. Grubesic 《Growth and change》2015,46(1):58-80
This paper introduces the Broadband Provision Tensor (BPT), a new fusion‐based multivariate approach for exploring the spatial, economic, and quality of service dimensions of broadband telecommunication services. Specifically, the BPT allows for the development of a more complex and realistic typology of broadband provision between regions within a uniform geographic scale. Thus, regardless of the BPT being implemented for states, metropolitan areas, counties, municipalities, census tracts, or block groups, the units included in the chosen scale of analysis can be compared and benchmarked against their peers. Ultimately, the BPT allows analysts and policy makers to succinctly visualize the broadband provision status regions across multiple dimensions for comparative purposes. This paper highlights an application of the BPT for 439 municipalities in the U.S. using a combination of Ookla Net Metrics data and provision information from the National Broadband Map. Results suggest a highly varied spectrum of wireline broadband provision profiles in the U.S. Policy implications are discussed. 相似文献
24.
Ryan D Antolovich M Herlt T Prenzler PD Lavee S Robards K 《Journal of agricultural and food chemistry》2002,50(23):6716-6724
A methodological approach to phenolic profiling making extensive use of LC-MS with extracted ion chromatograms was applied to extracts of five different olive tissues: pulp, seed, stone, new-season leaves, and old-season leaves. Tissue extracts of the cultivars Hardy's Mammoth, Corregiola, Verdale, and Manzanillo were analyzed by HPLC with UV and ESI MS detection. Chromatograms of samples of green Hardy's Mammoth drupes, a uniquely Australian olive cultivar, were dominated by a large, broad peak. This peak was not attributable to oleuropein, which is usually the dominant phenolic compound in green olive fruit, but the phenolic compound I. This compound was isolated by semipreparative HPLC and characterized by 1D- and 2D-NMR. Extraction studies showed that the compound was not likely to be an artifact of an enzymatic degradation process. Tritium labeling studies were used to establish a possible relationship between the biosynthesis of I and oleuropein. 相似文献
25.
Spatial changes of soil fungal and bacterial biomass from a sub-alpine coniferous forest to grassland in a humid, sub-tropical region 总被引:7,自引:0,他引:7
Fungal and bacterial biomass were determined across a gradient from a forest to grassland in a sub-alpine region in central
Taiwan. The respiration-inhibition and ergosterol methods for the evaluation of the microbial biomass were compared. Soil
fungal and bacterial biomass both significantly decreased (P<0.05) with the shift of vegetation from forest to grassland. Fungal and bacterial respiration rates (evolved CO2) were, respectively, 89.1 μl CO2 g–1 soil h–1 and 55.1 μl CO2 g–1 soil h–1 in the forest and 36.7 μl CO2 g–1 soil h–1 and 35.7 μl CO2 g–1 soil h–1 in the grassland surface soils (0–10 cm). The fungal ergosterol content in the surface soil decreased from the forest zone
(108 μg g–1) to the grassland zone (15.9 μg g–1). A good correlation (R
2=0.90) was exhibited between the soil fungal ergosterol content and soil fungal CO2 production (respiration) for all sampling sites. For the forest and grassland soil profiles, microbial biomass (respiration
and ergosterol) declined dramatically with depth, ten- to 100-fold from the surface organic horizon to the deepest mineral
horizon. With respect to fungal to bacterial ratios for the surface soil (0–10 cm), the forest zone had a significantly (P<0.05) higher ratio (1.65) than the grassland zone (1.05). However, there was no fungal to bacterial ratio trend from the surface
horizon to the deeper mineral horizons of the soil profiles.
Received: 30 March 2000 相似文献
26.
Wang Dechun Prato Tony Qiu Zeyuan Kitchen Newell R. Sudduth Kenneth A. 《Precision Agriculture》2003,4(1):35-52
Variable Rate Technology (VRT) has the potential to increase crop yields and improve water quality relative to Uniform Rate Technology (URT). The effects on profitability and water quality of adopting VRT for nitrogen (N) and lime were evaluated for corn production on four claypan soil fields in north central Missouri under average to better than average weather conditions. Variable N and lime rates were based on measured topsoil depth and soil pH, respectively. VRT rates were compared to two different uniform N applications (URT-Nl based on the topsoil depth within these claypan soil fields, and URT-N2 based on a typical N rate for corn production in this area). Expected corn yield was predicted based on topsoil depth, soil pH, N rate, and lime rate. Water quality benefits of VRT relative to URT were evaluated based on potential leachable N. Sensitivity analyses were performed using simulated topsoil data for topsoil depth and soil pH. Results showed that VRT was more profitable than URT in the four sample fields under URT-N1, and in two of the four fields under URT-N2. Greater variation in topsoil depth and soil pH resulted in higher profitability and greater water quality benefits with VRT. Results support adoption of VRT for N and lime application for other claypan soil fields with characteristics similar to those in the fields used in this study. 相似文献
27.
Bakal C Linding R Llense F Heffern E Martin-Blanco E Pawson T Perrimon N 《Science (New York, N.Y.)》2008,322(5900):453-456
Cellular signaling networks have evolved to enable swift and accurate responses, even in the face of genetic or environmental perturbation. Thus, genetic screens may not identify all the genes that regulate different biological processes. Moreover, although classical screening approaches have succeeded in providing parts lists of the essential components of signaling networks, they typically do not provide much insight into the hierarchical and functional relations that exist among these components. We describe a high-throughput screen in which we used RNA interference to systematically inhibit two genes simultaneously in 17,724 combinations to identify regulators of Drosophila JUN NH(2)-terminal kinase (JNK). Using both genetic and phosphoproteomics data, we then implemented an integrative network algorithm to construct a JNK phosphorylation network, which provides structural and mechanistic insights into the systems architecture of JNK signaling. 相似文献
28.
Frudakis T 《Science (New York, N.Y.)》2008,319(5866):1039-40; author reply 1039-40
29.
Femtosecond laser irradiation is used to excite adsorbed CO molecules on a Cu110 surface; the ensuing motion of individual molecules across the surface is characterized on a site-to-site basis by in situ scanning tunneling microscopy. Adsorbate motion both along and perpendicular to the rows of the Cu110 surface occurs readily, in marked contrast to the behavior seen for equilibrium diffusion processes. The experimental findings for the probability and direction of the molecular motion can be understood as a manifestation of strong coupling between the adsorbates' lateral degrees of freedom and the substrate electronic excitation produced by the femtosecond laser radiation. 相似文献
30.