全文获取类型
收费全文 | 266篇 |
免费 | 17篇 |
国内免费 | 32篇 |
出版年
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 8篇 |
2020年 | 8篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 8篇 |
2016年 | 3篇 |
2015年 | 9篇 |
2014年 | 18篇 |
2013年 | 26篇 |
2012年 | 12篇 |
2011年 | 12篇 |
2010年 | 8篇 |
2009年 | 11篇 |
2008年 | 8篇 |
2007年 | 11篇 |
2006年 | 16篇 |
2005年 | 10篇 |
2004年 | 16篇 |
2003年 | 13篇 |
2002年 | 14篇 |
2001年 | 9篇 |
2000年 | 9篇 |
1999年 | 8篇 |
1998年 | 2篇 |
1997年 | 4篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 7篇 |
1993年 | 3篇 |
1992年 | 4篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有315条查询结果,搜索用时 140 毫秒
311.
312.
研究了梨锈病菌(Gymnosporangium haraeanum Syd.)冬孢子角在不同含水量和温度条件下的开裂和繁殖情况,并通过调研及监测手段研究了山西梨产区2019年锈病的发生情况,在此基础上,结合气象因子对梨锈病发生与流行条件进行了探究.结果表明,15~20℃条件下,发育成熟的梨锈病冬孢子角浸水10min可开裂,12h可检测到冬孢子和发育的担孢子;山西省梨产区锈病发生程度从北到南依次加重;4月份降水后平均温度≥15℃的环境条件,是诱发锈病发生的主要因子,为防控的关键点. 相似文献
313.
The polygalacturonase activity in extracts of ripe D'Anjou pears is due to two enzymes, which can be resolved by chromatography on Sephadex G-100. One 相似文献
314.
315.
Since CO2 is liberated in the conversion of ACC to ethylene, the evidence that ethylene production by plant tissues is actually promoted by CO2 calls for an explanation. Accordingly, the formation of ethylene by oat (Avena sativa L. cv. Victory) leaves and by apple (Golden Delicious) and pear (Pyrus communis L. cv. Anjou) tissue in very low levels of CO2 has been studied. The gas chromatograph was modified to measure CO2 and ethylene at the same time, by reducing both to methane. (Response of the gas chromatograph to CO2 concentrations is linear.) The work establishes a clear difference between the endogenous production of ethylene and its production from applied ACC, a difference which holds about equally for leaves and for fruit tissue. The difference is in the CO2 requirement, namely, lowering the CO2 level by 99% or more decreases the production of ethylene from applied ACC by 50–60%, but it does not decrease, or even slightly increases, its production from endogenous precursors. Thus, while the need for CO2 has not been explained, it has at least been delimited. The responses to abscisic acid (ABA) also differ, but in the reverse direction, the endogenous production of ethylene being decreased up to 70% by ABA. while the liberation from ACC is promoted about 20%. ABA also promoted the respiratory CO2 production by 30% or, in presence of 1-aminocyclopropane-1-carboxylic acid (ACC), by over 50%. Inhibition of ethylene production by cobalt or EDTA shows no such differentiation, while inhibition by Na catechol-4,6-disulfonate (Tiron) shows a small difference. It is concluded either that endogenous ethylene is formed by an enzyme system different from that reacting with ACC, or (more likely) that when ethylene arises from endogenous precursors the reaction does not proceed by way of free ACC, but by some activated form of it. 相似文献