全文获取类型
收费全文 | 4872篇 |
免费 | 393篇 |
国内免费 | 5篇 |
出版年
2023年 | 14篇 |
2022年 | 8篇 |
2021年 | 71篇 |
2020年 | 50篇 |
2019年 | 67篇 |
2018年 | 76篇 |
2017年 | 86篇 |
2016年 | 145篇 |
2015年 | 224篇 |
2014年 | 262篇 |
2013年 | 305篇 |
2012年 | 359篇 |
2011年 | 350篇 |
2010年 | 224篇 |
2009年 | 248篇 |
2008年 | 323篇 |
2007年 | 294篇 |
2006年 | 324篇 |
2005年 | 290篇 |
2004年 | 299篇 |
2003年 | 277篇 |
2002年 | 253篇 |
2001年 | 59篇 |
2000年 | 36篇 |
1999年 | 58篇 |
1998年 | 51篇 |
1997年 | 33篇 |
1996年 | 25篇 |
1995年 | 36篇 |
1994年 | 40篇 |
1993年 | 34篇 |
1992年 | 38篇 |
1991年 | 24篇 |
1990年 | 26篇 |
1989年 | 21篇 |
1988年 | 14篇 |
1987年 | 14篇 |
1986年 | 17篇 |
1985年 | 17篇 |
1984年 | 26篇 |
1983年 | 15篇 |
1982年 | 16篇 |
1981年 | 15篇 |
1980年 | 17篇 |
1979年 | 11篇 |
1978年 | 9篇 |
1977年 | 13篇 |
1976年 | 10篇 |
1975年 | 8篇 |
1974年 | 6篇 |
排序方式: 共有5270条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
Genetically modified cells of Pseudomonas fluorescens, chromosomally marked with genes for bioluminescence, were inoculated into sterile soil microcosms. During incubation for 90 days, viable cell concentration did not change significantly but light output, measured by luminometry, decreased, indicating reduced metabolic activity due to lack of substrates. Amendment with nutrients resulted in parallel increases in both luminescence and dehydrogenase activity. Luminometry therefore enables rapid monitoring of the activity of populations of luminescence-marked microbial inocula in the soil, with greater sensitivity and selectivity than traditional techniques. 相似文献
5.
6.
Plant activators are agrochemicals that activate the plant immune system, thereby enhancing disease resistance. Due to their prophylactic and durable effects on a wide spectrum of diseases, plant activators can provide synergistic crop protection when used in combination with traditional pest controls. Although plant activators have achieved great success in wet-rice farming practices in Asia, their use is still limited. To isolate novel plant activators applicable to other crops, we screened a chemical library using a method that can selectively identify immune-priming compounds. Here, we report the isolation and characterization of three diuretics, bumetanide, bendroflumethiazide and clopamide, as immune-priming compounds. These drugs upregulate the immunity-related cell death of Arabidopsis suspension-cultured cells induced with an avirulent strain of Pseudomonas syringae pv. tomato in a concentration-dependent manner. The application of these compounds to Arabidopsis plants confers disease resistance to not only the avirulent but also a virulent strain of the pathogen. Unlike salicylic acid, an endogenous phytohormone that governs disease resistance in response to biotrophic pathogens, the three diuretic compounds analyzed here do not induce PR1 or inhibit plant growth, showing potential as lead compounds in a practical application. 相似文献
7.
A set of plasmids containing portions of the Col El plasmid were transformed into recA− cells. These cells, after UV irradiation, only incorporate labelled amino acids into plasmid-encoded proteins. UV-irradiated cells label a 14.5 kDa band if they are phenotypically immune to colicin E1, and do not contain this band if they are sensitive to colicin E1. We conclude that the 14.5 kDa protein is the colicin E1 immunity protein. When the inner and outer membranes of these cells are fractionated, the labelled band appears in the inner membrane. The immunity protein must be an intrinsic inner membrane protein, confirming the predictions made by hydrophobicity calculations from primary sequence data.MaxicellCol El plasmidImmunity proteinHydrophobicity calculation 相似文献
8.
9.
10.
Gillian D Alton David L Pearl Ken G Bateman W Bruce McNab Olaf Berke 《BMC veterinary research》2010,6(1):42