首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   959篇
  免费   105篇
  国内免费   17篇
电工技术   11篇
综合类   58篇
化学工业   292篇
金属工艺   57篇
机械仪表   62篇
建筑科学   49篇
矿业工程   13篇
轻工业   69篇
水利工程   2篇
石油天然气   15篇
武器工业   12篇
无线电   106篇
一般工业技术   189篇
冶金工业   24篇
原子能技术   4篇
自动化技术   118篇
  2025年   7篇
  2024年   17篇
  2023年   23篇
  2022年   41篇
  2021年   49篇
  2020年   41篇
  2019年   41篇
  2018年   26篇
  2017年   43篇
  2016年   43篇
  2015年   43篇
  2014年   69篇
  2013年   58篇
  2012年   53篇
  2011年   77篇
  2010年   52篇
  2009年   50篇
  2008年   41篇
  2007年   50篇
  2006年   33篇
  2005年   37篇
  2004年   37篇
  2003年   13篇
  2002年   23篇
  2001年   20篇
  2000年   13篇
  1999年   9篇
  1998年   4篇
  1997年   7篇
  1996年   13篇
  1995年   12篇
  1994年   2篇
  1993年   2篇
  1992年   4篇
  1991年   5篇
  1990年   5篇
  1989年   2篇
  1988年   3篇
  1987年   1篇
  1985年   1篇
  1984年   6篇
  1983年   3篇
  1982年   1篇
  1979年   1篇
排序方式: 共有1081条查询结果,搜索用时 0 毫秒
101.
本论述了应用紫外线电离法进行SF6气体检测的原理,并阐述了SF6检测仪关键部件的电路结构,同时也简明地叙述了应用软件技术进行非线性处理,零点飘移及仪器标定方法。  相似文献   
102.
广西老堡铅锌矿褶皱形成机制及其控矿规律   总被引:1,自引:0,他引:1  
老堡铅锌矿床主要赋存在陡山沱组白云岩或老堡组硅质岩中,顺层产出,受地层与褶皱的双重控制。矿区主干褶皱为一复式向斜,由2个次级向斜和1个次级背斜组成。从构造几何学、运动学角度,运用现代测试技术,对矿区的小构造、显微构造和组构进行构造分析后揭示,老堡褶皱构造的形成机制是以弯滑作用为主、兼具弯流作用的纵弯褶皱作用的产物。铅锌矿体主要赋存在褶皱的转折端虚脱部位及两翼滑移量较大的层间滑动破碎带中。  相似文献   
103.
折叠翼的结构非线性颤振分析   总被引:2,自引:0,他引:2  
杨宁  吴志刚  杨超  曹奇凯 《工程力学》2012,29(2):197-204
由于折叠机构间隙的存在,折叠翼的刚度特性呈非线性关系特性,工程实践中需要有效的方法,建立并求解折叠翼的非线性气动弹性方程。该文提出了弦向多个自由度具有结构非线性刚度的折叠翼颤振分析方法,并对典型折叠翼面进行了非线性颤振分析。利用动态子结构方法建立了非线性气动弹性方程,分别在频域和时域给出了颤振求解方法。对比工程软件的计算结果,验证了该方法是否满足工程计算精度的要求。通过对典型折叠翼的计算得到以下结论。在弦向多个位置具有初载间隙型非线性的典型折叠翼结构在一定速度范围内会产生稳定的极限环振荡,在一定速度范围内结构响应与初始扰动相关,后缘铰链振动相比于前缘更加剧烈,初载角较大时振荡更加剧烈。  相似文献   
104.
Bioactive peptides often contain several disulfide bonds that provide the main contribution to conformational rigidity and structural, thermal, or biological stability. Among them, cystine‐knot peptides—commonly named “knottins”—make up a subclass with several thousand natural members. Hence, they are considered promising frameworks for peptide‐based pharmaceuticals. Although cystine‐knot peptides are available through chemical and recombinant synthetic routes, oxidative folding to afford the bioactive isomers still remains a crucial step. We therefore investigated the oxidative folding of ten protease‐inhibiting peptides from two knottin families, as well as that of an HIV entry inhibitor and of aprotinin, under two conventional sets of folding conditions and by a newly developed procedure. Kinetic studies identified folding conditions that resulted in correctly folded miniproteins with high rates of conversion even for highly hydrophobic and aggregation‐prone peptides in concentrated solutions.  相似文献   
105.
106.
    
A common interpretation of Anfinsen's hypothesis states that one amino acid sequence should fold into a single, native, ordered state, or a highly similar set thereof, coinciding with the global minimum in the folding-energy landscape, which, in turn, is responsible for the function of the protein. However, this classical view is challenged by many proteins and peptide sequences, which can adopt exchangeable, significantly dissimilar conformations that even fulfill different biological roles. The similarities and differences of concepts related to these proteins, mainly chameleon sequences, metamorphic proteins, and switch peptides, which are all denoted herein “turncoat” polypeptides, are reviewed. As well as adding a twist to the conventional view of protein folding, the lack of structural definition adds clear versatility to the activity of proteins and can be used as a tool for protein design and further application in biotechnology and biomedicine.  相似文献   
107.
    
In living organisms, protein folding and function take place in an inhomogeneous, highly crowded environment possessing a concentration of diverse macromolecules of up to 400 g/L. It has been shown that the intracellular environment has a pronounced effect on the stability, dynamics and function of the protein under study, and has for this reason to be considered. However, most protein studies neglect the presence of these macromolecules. Consequently, we probe here the overall thermodynamic stability of cold shock protein B from Bacillus subtilis (BsCspB) in cell lysate. We found that an increase in cell lysate concentration causes a monotonic increase in the thermodynamic stability of BsCspB. This result strongly underlines the importance of considering the biological environment when inherent protein parameters are quantitatively determined. Moreover, we demonstrate that targeted application of 19F NMR spectroscopy operates as an ideal tool for protein studies performed in complex cellular surroundings.  相似文献   
108.
Protein unfolding inside immobilized polymerosomes : One of the most interesting properties of polymeric vesicles is their remarkable stability against extreme temperatures and osmotic stress, and their longevity even under harsh environmental conditions. We have demonstrated, in an application on protein folding, that surface‐tethered polymerosomes are suitable for performing time‐resolved single molecule studies with encapsulated proteins, as illustrated here.

  相似文献   

109.
A combined strategy to obtain a partial NMR assignment of the neuronal Tau protein is presented. Confronted with the extreme spectral degeneracy that the spectrum of this 441 amino acid long unstructured protein presents, we have introduced a graphical procedure based on residue type-specific product planes. Combining this strategy with the search for pairwise motifs, and combining the spectra of different Tau isoforms and even of peptides derived from the native sequence, we arrive at a partial assignment that is sufficient to map the interactions of Tau with its molecular partners. The obtained assignments equally confirm the absence of regular secondary structure in the isolated protein.  相似文献   
110.
蒋力 《净水技术》2004,23(3):35-37
张掖沙湾水厂的水力循环澄清池是上世纪70年代初建造。由于池深,各部分功能不匹配,动能有效利用率低,排泥不畅,对水量、水质变化适应性差,限制了产水量的提高。经强化絮凝、增设斜管、折板等综合性改造后.单池产水量由原来80m^3/d增加到140m^3/d,药耗降低了15%~20%。改造后仅1年多时间.即可从增产水的效益和节省药耗中收回投资。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号