全文获取类型
收费全文 | 575篇 |
免费 | 46篇 |
国内免费 | 18篇 |
专业分类
电工技术 | 2篇 |
综合类 | 41篇 |
化学工业 | 131篇 |
金属工艺 | 2篇 |
机械仪表 | 10篇 |
建筑科学 | 18篇 |
矿业工程 | 3篇 |
能源动力 | 17篇 |
轻工业 | 244篇 |
水利工程 | 44篇 |
石油天然气 | 2篇 |
无线电 | 32篇 |
一般工业技术 | 23篇 |
冶金工业 | 7篇 |
原子能技术 | 1篇 |
自动化技术 | 62篇 |
出版年
2024年 | 2篇 |
2023年 | 10篇 |
2022年 | 13篇 |
2021年 | 32篇 |
2020年 | 23篇 |
2019年 | 25篇 |
2018年 | 11篇 |
2017年 | 17篇 |
2016年 | 18篇 |
2015年 | 22篇 |
2014年 | 24篇 |
2013年 | 38篇 |
2012年 | 47篇 |
2011年 | 33篇 |
2010年 | 29篇 |
2009年 | 35篇 |
2008年 | 19篇 |
2007年 | 31篇 |
2006年 | 28篇 |
2005年 | 24篇 |
2004年 | 17篇 |
2003年 | 11篇 |
2002年 | 14篇 |
2001年 | 10篇 |
2000年 | 15篇 |
1999年 | 14篇 |
1998年 | 7篇 |
1997年 | 3篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1994年 | 12篇 |
1993年 | 7篇 |
1992年 | 12篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有639条查询结果,搜索用时 15 毫秒
61.
62.
烤烟叶绿素含量遗传分析 总被引:3,自引:0,他引:3
应用主基因+多基因6个世代联合分析方法对烤烟丸叶×Coker319组合的总叶绿素含量性状进行了分析。结果表明:丸叶×Coker319组合的总叶绿素含量受1对加性-显性主基因+加性-显性-上位性多基因控制,主基因加性效应为-5.89,主基因显性效应为-3.47;B1、B2和F2世代总叶绿素含量的主基因遗传率分别为3.61%、46.11%和48.94%;多基因遗传率分别为52.04%、8.25%和0.00%,说明F2世代总叶绿素含量表现出较高的主基因遗传率,并受环境影响。对烤烟总叶绿素含量的改良要以主基因为主,同时注意环境的影响。 相似文献
63.
研究了不同浓度钛溶液灌根对烤烟生长过程中各种生理特性的影响.结果表明:在伸根期用适量的钛肥灌根,能增加烤烟叶片中叶绿素、类胡萝卜素含量和转化酶活性,可以促进烤烟的光合作用,有利于烟草同化产物的转化和利用,同时也能够提高烤烟叶片中SOD和POD活性,降低MDA含量,明显降低烟叶中细胞膜脂过氧化程度,提高烤烟抗衰老能力和抗逆性.上述作用,在钛肥灌根的短期内,效果尤为明显,其中富钛增效剂稀释600倍灌根效果最好. 相似文献
64.
Moein Moosavi-Nezhad Reza Salehi Sasan Aliniaeifard Georgios Tsaniklidis Ernst J. Woltering Dimitrios Fanourakis Krystyna uk-Goaszewska Hazem M. Kalaji 《International journal of molecular sciences》2021,22(15)
To investigate the importance of light on healing and acclimatization, in the present study, grafted watermelon seedlings were exposed to darkness (D) or light, provided by blue (B), red (R), a mixture of R (68%) and B (RB), or white (W; 35% B, 49% intermediate spectra, 16% R) LEDs for 12 days. Survival ratio, root and shoot growth, soluble carbohydrate content, photosynthetic pigments content, and photosynthetic performance were evaluated. Seedling survival was not only strongly limited in D but the survived seedlings had an inferior shoot and root development, reduced chlorophyll content, and attenuated photosynthetic efficiency. RB-exposed seedlings had a less-developed root system. R-exposed seedlings showed leaf epinasty, and had the smallest leaf area, reduced chlorophyll content, and suppressed photosynthetic apparatus performance. The R-exposed seedlings contained the highest amount of soluble carbohydrate and together with D-exposed seedlings the lowest amount of chlorophyll in their scions. B-exposed seedlings showed the highest chlorophyll content and improved overall PSII photosynthetic functioning. W-exposed seedling had the largest leaf area, and closely resembled the photosynthetic properties of RB-exposed seedlings. We assume that, during healing of grafted seedlings monochromatic R light should be avoided. Instead, W and monochromatic B light may be willingly adopted due to their promoting effect on shoot, pigments content, and photosynthetic efficiency. 相似文献
65.
干重法、比浊法和叶绿素a含量换算法是测定液体悬浮培养发状念珠蓝细菌常用的3种方法.该研究对这3种常用测定方法的条件进行了确定,并对适用性进行比较.结果显示,干重法烘干条件确定为80℃,6.5h~9.5h;比浊法用波长为750nm;叶绿素a含量换算法测定波长为675nm.测定培养初期的发状念珠蓝细菌,比浊法测定数值略高于干重法和叶绿素a含量换算法所测数值,且具有更高的敏感性;培养中期3种方法所测数值较接近,且重复性好;培养末期,细胞内叶绿素含量降低,用叶绿素a含量换算法测定结果低于干重法及比浊法. 相似文献
66.
67.
68.
69.
为探讨三峡水库蓄水以来竺溪河-澎溪河回水区叶绿素a的分布及其影响因素,2013年1月1日至2014年12月,在竺溪河-澎溪河河段设置了8个采样点,对叶绿素a及相关环境因子进行了监测。依据监测信息和资料,对竺溪河-澎溪河河段富营养化状态、叶绿素a和相关环境因子的空间分布特性及其相关性进行了分析。结果表明:竺溪河和澎溪河均处于不同程度的富营养化状态,且受干流倒灌的影响,回水区首端的富营养化程度具有季节性变化特点;竺溪河和澎溪河回水区各采样点叶绿素a和TN,TP的相关性系数均值分别为澎溪河-0.014,-0.014,竺溪河为0.154,0.244,而干流为0.469,0.449。该结果也说明,TN和TP对支流回水区藻类生长的影响比较小,而与干流的叶绿素a浓度呈相对明显的相关关系。 相似文献
70.
Lourdes?Gallardo-Guerrero María?Roca M?Isabel Mínguez-MosqueraEmail author 《Journal of the American Oil Chemists' Society》2002,79(1):105-109
The present work has studied the content and type of pigments present in olive fruits and the respective oils and alperujos.
The concentration of isochromic pigment fractions—chlorophylls and carotenoids—decreased with fruit ripening, more markedly
in the former than in the latter. This implied that the ratio between the two pigment fractions also decreased in parallel
in the three products studied. However, the value in the oil was lower than in the fruit, and that in the alperujo was much
higher. During the extraction process, the release of acids may have caused pheophytinization reactions in the chlorophyll
fraction, increasing pheophytin content in alperujos and oils, whereas the carotenoid fraction was affected only in the alperujo.
Chlorophyll b derivatives were destroyed in greater proportion than chlorophyll a derivatives during transfer to the oil. During processing the destruction of lutein was greater than that of β-carotene.
The balance of matter between fruit, alperujo, and oil indicated that not all the fruit pigmentation was released from the
structures, and most remained occluded in the alperujo. The rest of the pigmentation, and particularly the chlorophyll fraction,
was partly destroyed during its transfer to the oil. 相似文献