全文获取类型
收费全文 | 48篇 |
免费 | 7篇 |
国内免费 | 4篇 |
专业分类
系统科学 | 11篇 |
丛书文集 | 1篇 |
教育与普及 | 1篇 |
理论与方法论 | 1篇 |
综合类 | 45篇 |
出版年
2025年 | 1篇 |
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2016年 | 3篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 4篇 |
2012年 | 3篇 |
2011年 | 2篇 |
2010年 | 3篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2007年 | 2篇 |
2005年 | 3篇 |
2004年 | 5篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1997年 | 3篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有59条查询结果,搜索用时 15 毫秒
21.
采用气相色谱-质谱联用法(GC-MS)测定金果榄中脂肪酸的组成,共鉴定了15个化学成分,确定了金果榄所含有的5种主要脂肪酸,其中亚油酸质量分数为38.94%、顺式-13-十八酸甲酯质量分数为24.97%、棕榈酸质量分数为18.77%、硬脂酸质量分数为5.94%、十七烷酸质量分数为3.12%. 相似文献
22.
TAC(IEEE Trans.On Automatic Control)和Automatica是控制理论领域国际著名期刊。"控制理论与方法"(F0301)是国家自然科学基金二级申请代码,内含21个三级申请代码,基本涵盖了控制理论的各个研究方向。本文基于1986—2009年期间,中国大陆学者在TAC和Automatica上发表的论文数、标注自然科学基金资助的论文数以及同期科学基金在"控制理论与方法"领域资助的项目数和经费数,采用相关性、因果性等分析方法进行综合分析。结果表明,科学基金对推动我国控制理论与控制工程学科的发展起到了越来越重要的作用。 相似文献
23.
Di Wu TianLei Xu Jing Sun JianXin Dai GuoHui Ding Yungang He ZhengFeng Zhou Hui Xiong Hui Dong WeiRong Jin Chao Bian Li Jin HongYan Wang XiaoNing Wang Zhong Yang Yang Zhong Hao Wang XiaoYan Che Zhong Huang Ke Lan Bing Sun Fan Wu ZhenAn Yuan Xi Zhang XiaoNong Zhou JiaHai Zhou ZhiYong Ma GuangZhi Tong YaJun Guo GuoPing Zhao YiXue Li ZhiWei Cao 《科学通报(英文版)》2009,54(13):2171-2173
In recent months, a novel influenza virus H1N1 broke out around the world. With bioinformatics technology, the 3D structure of HA protein was obtained, and the epitope residues were predicted with the method developed in our group for this novel flu virus. 58 amino acids were identified as potential epitope residues, the majority of which clustered at the surface of the globular head of HA protein. Although it is located at the similar position, the epitope of HA protein for the novel H1N1 flu virus has obvious differences in the electrostatic potential compared to that of HA proteins from previous flu viruses. 相似文献
24.
本文介绍了安装在万吨水压机上用于实时在线测量大型锻压件尺寸的测量和控制系统的系统设计和组成,同时详述了关键技术难点.该系统的研制成功大大提高了大锻件尺寸的测量精度和万吨水压机的生产效率,提高了工人的操作安全性,降低了工人的劳动强度. 相似文献
25.
本文提出了在纸张生产的自动控制系统中,应用微机对纸张定量,水份进行控制,探讨了控制系统的模型及算式,介绍了整个系统的结构,对造纸生产有一定实用价值。 相似文献
26.
27.
Wen B Li H Lu D Song X Zhang F He Y Li F Gao Y Mao X Zhang L Qian J Tan J Jin J Huang W Deka R Su B Chakraborty R Jin L 《Nature》2004,431(7006):302-305
The spread of culture and language in human populations is explained by two alternative models: the demic diffusion model, which involves mass movement of people; and the cultural diffusion model, which refers to cultural impact between populations and involves limited genetic exchange between them. The mechanism of the peopling of Europe has long been debated, a key issue being whether the diffusion of agriculture and language from the Near East was concomitant with a large movement of farmers. Here we show, by systematically analysing Y-chromosome and mitochondrial DNA variation in Han populations, that the pattern of the southward expansion of Han culture is consistent with the demic diffusion model, and that males played a larger role than females in this expansion. The Han people, who all share the same culture and language, exceed 1.16 billion (2000 census), and are by far the largest ethnic group in the world. The expansion process of Han culture is thus of great interest to researchers in many fields. 相似文献
28.
石油醚萃取生漆后,用硅胶、MCI和ODS等多种分离填料进行三烯漆酚的分离制备,纯化的单体以H-NMR、3C-NMR和高分辨质谱鉴定结构.结果表明,石油醚可萃取得到大量漆酚,硅胶柱分离以石油醚-乙酸乙酯(V(石油醚)∶V(乙酸乙酯)=30∶1~10∶1)为洗脱溶剂进行粗分,MCI和ODS分离以甲醇-水(甲醇体积分数90%)为流动相进行纯化,最后得到较高纯度的单体漆酚(质量分数达96%),经鉴定为一种三烯漆酚,3-(8′Z,11′E,13′Z-pentadecatrienyl) catechol. 相似文献
29.
利用二维电离层理论模式,在地磁平静和太阳活动低年的情况下,模拟中低纬电离层峰值电子浓度NmF2和峰值高度hmF2的周年和半年变化规律.在考虑与不考虑理论模式输入电场的周年和半年变化两种情况下,对比分析研究了电场对电离层NmF2和hmF2周年和半年变化的影响.结果表明,当输入电场没有周年和半年变化分量时,模拟NmF2表现出一定的半年变化特征,而hmF2周年变化分量较强;当输入电场包含了周年和半年变化特征时,模拟NmF2和hmF2周年和半年变化特征明显改变,且这种改变随地方时和地磁纬度不同有较大的差别;电场对NmF2半年变化的影响无论是在强度还是范围上都明显大干对hmF2的影响,电场对NmF2的影响在赤道和驼峰区都比较明显,但对hmF2的影响主要集中在地磁赤道区.通过对比模拟NmF2和hmF2发现,中低纬电离层hmF2与NmF2半年变化具有一定的相关性,初步分析认为电离层电场及其关的"赤道喷泉"效应可能是这种相关性的重要纽带;电离层电场对hmF2半年变化的影响仅局限在地磁赤道地区,而对NmF2影响可达驼峰地区,因此hmF2与NmF2半年变化的相关性也仅在地磁赤道较为明显. 相似文献
30.
Change of proton motive force across thylakoid membrane in soybean leaf during state transitions 总被引:2,自引:0,他引:2
SUJihu SHENYungang 《科学通报(英文版)》2003,48(7):652-657
Change of proton gradient across thylakoid membrane in soybean leaves was studied with millisecond delayed light emission(ms-DLE) during the coures of state transitions which were indicated by the cholrophyll fluores-cence at room temperature and 77K.When dark-adapted leaves were induced to state Ⅰ with far-red light,Fm/F0,F685/F735 and the intensity of fast phase of ms-DLE were af-fected slightly.However,during the induction to state Ⅱ with red light,both Fm/F0 and F685/F735 decreased immedi-ately and the former were quicker than the latter.In this interval,the intesity of fast phase of ms-DLE increased to a maximum and then decreased to a lower valus during the transition to stateⅡ.Nigericin,an uncoupler which elimi-nates the proton gradient across thylakoid membrane,inhib-ited the increase in the intensity of fast phase of ms-DLE during the transition to state Ⅱ.Another uncoupler,valino-mycin,which eliminates the membrane potential,did not affect the changes of the intensity of fast phase.These results suggest that the prompt increase in the intensity of fast phase of ms-DLE at the beginning of transitions to state Ⅱ is cor-related mainly with the proton gradient released from water oxidation in photosystemⅡ. 相似文献