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   421篇
  免费   14篇
  国内免费   12篇
电工技术   19篇
技术理论   1篇
综合类   9篇
化学工业   101篇
金属工艺   4篇
机械仪表   9篇
建筑科学   8篇
能源动力   1篇
轻工业   29篇
水利工程   2篇
石油天然气   8篇
武器工业   2篇
无线电   135篇
一般工业技术   53篇
冶金工业   36篇
原子能技术   1篇
自动化技术   29篇
  2023年   2篇
  2022年   5篇
  2021年   6篇
  2020年   3篇
  2019年   2篇
  2018年   9篇
  2017年   8篇
  2016年   4篇
  2015年   7篇
  2014年   11篇
  2013年   11篇
  2012年   11篇
  2011年   17篇
  2010年   10篇
  2009年   7篇
  2008年   14篇
  2007年   18篇
  2006年   22篇
  2005年   11篇
  2004年   16篇
  2003年   16篇
  2002年   17篇
  2001年   13篇
  2000年   14篇
  1999年   23篇
  1998年   28篇
  1997年   24篇
  1996年   18篇
  1995年   10篇
  1994年   13篇
  1993年   14篇
  1992年   4篇
  1991年   3篇
  1989年   3篇
  1988年   3篇
  1987年   3篇
  1985年   4篇
  1984年   5篇
  1983年   2篇
  1982年   3篇
  1981年   2篇
  1980年   6篇
  1978年   2篇
  1976年   4篇
  1975年   4篇
  1974年   3篇
  1972年   5篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
排序方式: 共有447条查询结果,搜索用时 15 毫秒
441.
Monitoring complex biological assays such as in vitro protein synthesis over long periods in micrometer-sized cavities of poly(dimethyl siloxane) (PDMS) microfluidic devices requires a strategy that solves the adsorption and absorption problems on PDMS surfaces. In this study, we developed a technique that instantaneously arrays aqueous microdroplets coated with a phospholipid membrane within a single microfluidic device. The simple lipid bilayer coating effectively inhibits the adsorption of proteins and DNA, whereas the encapsulation of the droplet reduces the area in contact with the PDMS surface, resulting in decreased absorption in part. Although the size becomes smaller during the first few hours, a lipid-coated microdroplet array demonstrated a temporal stability of more than 20 h and a size uniformity of CV 3% in the device. Furthermore, we succeeded in expressing a green fluorescent protein by confining an in vitro translation system in the microdroplets, which was confirmed by scanning the fluorescence spectrum of the droplets, demonstrating that the lipid coat secured the synthetic reaction from the adsorption problem.  相似文献   
442.
Bonner sphere spectrometer (BSS) is used in radiation protection measurement because of its wide energy range (thermal to MeV) and easy operation. Mitsubishi Heavy Industries (MHI) has used BSS to obtain neutron spectrum and has used the neutron spectrum to estimate neutron dose or induced activity. Calibration of BSS is important to estimate precise neutron dose or induced activity. MHI BSS was calibrated at National Institute of Advanced Industrial Science and Technology (AIST). The calibration results at AIST are in good agreement with calculation results.  相似文献   
443.
针对GPS卫星信号在楼群密集的城市和室内存在定位盲区而无法单独完成定位的难题,提出GPS-DTMB组合导航定位方法。在多源信号组合导航定位系统中,为了解决导航定位精度与运算复杂度间的矛盾,研究改进的加权行列式选星算法在GPS与DTMB组合定位系统中的可行性,与传统最小GDOP选星算法相比较,改进的选星算法具有运算复杂度低、计算消耗时间短的优点,并且对比分析在不同的组合卫星数目中,该算法与直接利用传统最小GDOP选星算法相比较的偏差大小,仿真表明,在15种组合卫星中,偏差小于0.1的概率在90%左右,能够得到满意的性能,证明了此方法的实用性。  相似文献   
444.
We present an analytic method to approach Eilenberger equation and the associated Bogoliubov–de Gennes equation for quasi-1D fermionic gases. The problem of finding self-consistent inhomogeneous condensates is reduced to solving a certain class of nonlinear Schrödinger equations, whose most general solitonic solution is indeed available. Previously known solutions can be retrieved by taking appropriate limits in the parameters. The applicability of the method extends to systems with population imbalance and subject to external potential. In particular we show that fermionic zero-modes are robust against population imbalance.  相似文献   
445.
何骞  杜顺季  程铭宇 《城市勘测》2021,(4):16-18,22
城市更新基础数据调查是伴随城市更新工作深化而诞生的一项新型测绘项目,目前对该项目质量管理方面进行讨论分析的文献较少,通过总结分析已开展的项目经验,阐述了城市更新基础数据调查项目的工作流程,从制度标准、运行机制和过程控制三方面对该项目的质量控制的内容和要点进行探讨,为从事城市更新基础数据调查项目的管理和技术人员提供参考.  相似文献   
446.
In order to reveal the role of disulfide (S‐S) bonds in the fine structure of human hair fibers, especially in the complex between intermediate filaments (IFs) and intermediate filament‐associated proteins (IFAP), we investigated the relationship between melting behavior of (‐crystallites on thermal analysis and structural orientation of the fibers when S‐S bonds were oxidized using 1.5 wt% peracetic acid (PAA) solution. It was revealed that oxidative treatment of human hair fibers immersed in PAA solution made cystine residues dissociate to cysteic acids and that the (‐crystalline structure of the oxidized hair fibers was maintained despite the fission of S‐S bonds. Their thermographs in water on high pressure differential scanning calorimetry (HPD‐SC) showed that the endothermic peak assigned as the melting of (‐crystallites became separated into two endothermic peaks with progression of the treatment time, and the one started melting at a lower temperature while the other had a higher melting temperature than the melting temperature of untreated hair. Furthermore, the sum of the two endothermic peak areas decreased. Polarized light microscopic observation indicated that the orientation of IFAP still existed at the temperature at which the orientation of IFs disappeared. Therefore, these results suggested that some S‐S linkages at the interface between IFs and IFAP dissociated with the PAA treatment and that there was not only some region of IFs stabilized by S‐S bonds but also another region of IFs stabilized by hydrophobic interaction for their thermostability. Keywords: human hair fiber, peracetic acid, disulfide bonds, intermediate filament, (‐crystallites, thermostability, high pressure differential scanning calorimetry, polarized light microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy  相似文献   
447.
介绍Pinnacle软件的基线解算模型,用该软件对低纬度地区的实测数据解算结果进行分析和验证。结果表明该软件能满足城市控制网的基线处理要求,低纬度地区电离层影响明显,并且L1L2模型适合2 km内的短基线,L1L2c适合25 km内的基线,wide-lane模型则适合处理长度超过25 km的基线。  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