全文获取类型
收费全文 | 650篇 |
免费 | 35篇 |
专业分类
林业 | 40篇 |
农学 | 18篇 |
基础科学 | 7篇 |
109篇 | |
综合类 | 97篇 |
农作物 | 40篇 |
水产渔业 | 42篇 |
畜牧兽医 | 283篇 |
园艺 | 20篇 |
植物保护 | 29篇 |
出版年
2021年 | 15篇 |
2020年 | 8篇 |
2019年 | 16篇 |
2018年 | 8篇 |
2017年 | 14篇 |
2016年 | 20篇 |
2015年 | 11篇 |
2014年 | 18篇 |
2013年 | 31篇 |
2012年 | 30篇 |
2011年 | 29篇 |
2010年 | 26篇 |
2009年 | 21篇 |
2008年 | 31篇 |
2007年 | 22篇 |
2006年 | 19篇 |
2005年 | 27篇 |
2004年 | 30篇 |
2003年 | 17篇 |
2002年 | 26篇 |
2001年 | 14篇 |
2000年 | 15篇 |
1999年 | 17篇 |
1998年 | 5篇 |
1997年 | 7篇 |
1996年 | 4篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 12篇 |
1985年 | 12篇 |
1984年 | 10篇 |
1983年 | 9篇 |
1981年 | 7篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1977年 | 5篇 |
1976年 | 4篇 |
1971年 | 7篇 |
1970年 | 3篇 |
1969年 | 4篇 |
1968年 | 8篇 |
1967年 | 4篇 |
1966年 | 6篇 |
1963年 | 3篇 |
1955年 | 3篇 |
排序方式: 共有685条查询结果,搜索用时 15 毫秒
681.
682.
683.
684.
Okenna Obi-Njoku Michael Yongha Boh Gordon W. Price Andrea Gonzalez-Pavia Osborne Grant Clark 《Soil Use and Management》2023,39(1):161-182
Computational models are useful to estimate agricultural greenhouse gas emissions at regional scales. However, empirically based parameter values are required for the models to accurately represent carbon (C) and nitrogen (N) mineralization rates of different organic amendments in more and less humid regions or during wet and dry periods of the growing season. A controlled environment study was conducted to assess the rates of C and N mineralization in differently processed sewage sludge (biosolids) in wet and dry soil. Parameter values were estimated for use in modelling the degradation of three types of biosolids. A loam soil with either 49% water-filled pore space (WFPS) or 29% WFPS was amended with mesophilic anaerobically digested (digested), alkaline-stabilized, or composted biosolids. Headspace samples were collected and analysed for carbon dioxide (CO2) and nitrous oxide (N2O), and soil samples for nitrate () and ammonium (). Four different first-order models were fitted to the cumulative CO2–C and N2O–N data (R2 > 0.98), and soil (R2 > 0.65) and (R2 > 0.93) concentrations. CO2–C data indicated that C mineralization was higher in soil with 49% WFPS than in soils with 29% WFPS. Seventy-nine percent of the C compounds in digested biosolids degraded in soil with 49% WFPS, compared with 52% for alkaline-stabilized biosolids and 8% for composted biosolids. The fitted coefficient values were similar for all of the four first-order models used in this study and provide useful information for parameterizing more sophisticated mechanistic models of the degradation of biosolids in soil. 相似文献
685.
Grant M. Campbell Roberto Herrero‐Sanchez Roman Payo‐Rodriguez Maria Luisa Merchan 《Cereal Chemistry》2001,78(3):272-277
A new method for measuring dough densities is presented, based on weighing small dough samples in air and immersed in xylene. The method can be used to evaluate the air content of low‐density doughs and to follow the changing density of a proofing dough sample. The method is applied to evaluate the effect of flour strength and surfactant addition on dough aeration and subsequent proofing. Doughs were mixed in a high‐speed mixer from two flours, a strong breadmaking flour and a weak flour. Surfactants sodium stearoyl lactylate (SSL) and diacetyl tartrate esters of monoglyceride (DATEM) were added at three levels, and the air content, proofing dynamics, and baked loaf quality were evaluated. The air content of dough was proportional to headspace pressure in the mixer, while the strong flour occluded less air than the weak flour. Surfactants greatly improved the volume of baked loaves but appeared to have no significant effect on air incorporation during mixing. The addition of surfactants appeared to increase the rate of growth of the dough piece during proofing, possibly due to increased bubble breakup during mixing or to increased rates of mass transfer of CO2 into bubbles during proofing. 相似文献