全文获取类型
收费全文 | 4608篇 |
免费 | 228篇 |
国内免费 | 2篇 |
专业分类
林业 | 328篇 |
农学 | 166篇 |
基础科学 | 15篇 |
1235篇 | |
综合类 | 223篇 |
农作物 | 356篇 |
水产渔业 | 516篇 |
畜牧兽医 | 1569篇 |
园艺 | 100篇 |
植物保护 | 330篇 |
出版年
2024年 | 3篇 |
2023年 | 43篇 |
2022年 | 84篇 |
2021年 | 193篇 |
2020年 | 185篇 |
2019年 | 232篇 |
2018年 | 179篇 |
2017年 | 185篇 |
2016年 | 182篇 |
2015年 | 136篇 |
2014年 | 201篇 |
2013年 | 311篇 |
2012年 | 390篇 |
2011年 | 363篇 |
2010年 | 208篇 |
2009年 | 188篇 |
2008年 | 298篇 |
2007年 | 315篇 |
2006年 | 221篇 |
2005年 | 189篇 |
2004年 | 158篇 |
2003年 | 159篇 |
2002年 | 161篇 |
2001年 | 23篇 |
2000年 | 20篇 |
1999年 | 23篇 |
1998年 | 17篇 |
1997年 | 13篇 |
1996年 | 11篇 |
1995年 | 11篇 |
1994年 | 11篇 |
1993年 | 9篇 |
1992年 | 8篇 |
1991年 | 4篇 |
1990年 | 10篇 |
1989年 | 12篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1969年 | 3篇 |
1966年 | 4篇 |
排序方式: 共有4838条查询结果,搜索用时 0 毫秒
91.
92.
93.
Heimler D Vignolini P Dini MG Romani A 《Journal of agricultural and food chemistry》2005,53(8):3053-3056
The antiradical activity of dry beans was evaluated in order to assess the validity of this test and to correlate the results with those achieved with the Folin-Ciocalteu method and with a rapid spectrophotometric method for the analysis of total flavonoids. Four landraces (12 samples) of common beans (Phaseolus vulgaris L.), collected in two regions of Italy (Tuscany and Basilicata) in three different years, were analyzed. The EC50 values ranged from 39 to 2810 mg sample/mg 1,1-diphenyl-2-picrylhydrazil radical. The phenolic content of each sample was expressed as gallic acid equivalents; it changed from 1.17 to 4.40 mg/g. The flavonoid content, expressed as mg of (+)-catechin per g of dry seeds, ranged from 0.24 to 1.43 mg/g. The qualiquantitative composition of polyphenols has been also elucidated by means of high-performance liquid chromatography (HPLC)-diode array detection and HPLC/MS. These investigations showed that rapid tests can contribute to assessing the quality of functional food. 相似文献
94.
95.
96.
Martinelli Luiz A. Krusche Alex V. Vicgoria Reynaldo L. De Camargo Plinio B. Bernardes Marcelo Ferraz Epaminondas S. De Moraes Jorge M. Ballester Maria Victoria 《Water, air, and soil pollution》1999,110(1-2):67-79
Water samples were collected from 7 locations along major rivers of Piracicaba River basin for 22 months. The 4 upstream points represent non-polluted sites and the 3 downriver points represent polluted sites. Due to sewage input, concentrations of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), major conservative cations and anions increased significantly in the polluted sites. The major increases were observed for sodium, chloride and sulfate. Nitrate was an exception for this pattern, with similar concentrations between polluted and non-polluted sites. The probable cause was reduction of nitrate to ammonium in the polluted sites, where anoxic conditions prevail. Most of the variables had an inverse correlation with water discharge, especially in the polluted points. The sewage load was diluted by precipitation and surface waters. 相似文献
97.
Matthias Waibel Kevin McDonnell Maria Tuohy Sally Shirran Sylvia Synowsky Barry Thornton Eric Paterson Fiona Brennan Florence Abram 《European Journal of Soil Science》2023,74(3):e13392
Soil organic matter (SOM) is biologically, chemically, and physically complex. As a major store of nutrients within the soil, it plays an important role in nutrient provision to plants. An enhanced understanding of SOM utilisation processes could underpin better fertiliser management for plant growth, with reduced environmental losses. Metaproteomics can allow the characterisation of protein profiles and could help gain insights into SOM microbial decomposition mechanisms. Here, we applied three different extraction methods to two soil types to recover SOM with different characteristics. Specifically, water-extractable organic matter, mineral-associated organic matter and protein-bound organic matter were targeted with the aim to investigate the metaproteome enriched in those extractions. As a proof-of-concept, replicated extracts from one soil were further analysed for peptide identification using liquid chromatography followed by tandem mass spectrometry. We employed a framework for mining mass spectra for both peptide assignment and fragmentation pattern characterisation. Different extracts were found to exhibit contrasting total protein and humic substance content for the two soils investigated. Overall, water extracts displayed the lowest humic substance content (in both soils) and the highest number of peptide identifications (in the soil investigated) with the most frequent peptide hits associated with diverse substrate/ligand binding proteins of Proteobacteria and derived taxa. Our framework also highlighted a strong peptidic signal in unassigned and unmatched spectra, information that is currently not captured by the pipelines employed in this study. Taken together, this work points to specific areas for optimisation in chromatography and mass spectrometry to adequately characterise SOM-associated metaproteomes. 相似文献
98.
Cucu Maria Alexandra Said-Pullicino Daniel Maurino Valter Bonifacio Eleonora Romani Marco Celi Luisella 《Biology and Fertility of Soils》2014,50(5):755-764
Biology and Fertility of Soils - Temporal nitrogen (N) availability in fertilized rice paddies is the result of a balance of processes, mainly the gross rates of N mineralization, microbial and... 相似文献
99.
Argyri K Miller DD Glahn RP Zhu L Kapsokefalou M 《Journal of agricultural and food chemistry》2007,55(25):10221-10225
Milk proteins, during digestion, produce a range of biologically active peptides. Among those are peptides that may enhance iron absorption. The objective of this project was to investigate the effect of isolated milk peptides on iron uptake. Cow's milk, 0% fat, was subjected to a modified in vitro digestion process. The milk digest was further fractionated by gel filtration. All eluted fractions as well as beta-casein synthetic peptides (a tripeptide and a hexapeptide) were subsequently tested for effects on iron uptake with Caco-2 cell monolayers. Fractions of milk digests obtained through Sephadex G-25 gel filtration had a significant enhancing effect on iron uptake in Caco-2 cells compared to nonfractionated milk digests. Two fractions (P = 0) and the hexapeptide (P < 0.0001) enhanced iron uptake by up to 3-fold, whereas others and the tripeptide had no effect. These results suggest that selected peptides produced during the in vitro digestion of milk may enhance iron absorption; however, it remains to be demonstrated whether this effect may be nutritionally significant. 相似文献
100.