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   1512篇
  免费   62篇
  国内免费   6篇
电工技术   64篇
综合类   7篇
化学工业   341篇
金属工艺   28篇
机械仪表   38篇
建筑科学   28篇
矿业工程   2篇
能源动力   52篇
轻工业   170篇
水利工程   16篇
石油天然气   11篇
无线电   156篇
一般工业技术   235篇
冶金工业   307篇
原子能技术   9篇
自动化技术   116篇
  2023年   12篇
  2022年   26篇
  2021年   44篇
  2020年   29篇
  2019年   47篇
  2018年   39篇
  2017年   46篇
  2016年   42篇
  2015年   26篇
  2014年   45篇
  2013年   76篇
  2012年   53篇
  2011年   80篇
  2010年   48篇
  2009年   48篇
  2008年   61篇
  2007年   45篇
  2006年   41篇
  2005年   47篇
  2004年   40篇
  2003年   44篇
  2002年   33篇
  2001年   19篇
  2000年   26篇
  1999年   23篇
  1998年   119篇
  1997年   69篇
  1996年   60篇
  1995年   26篇
  1994年   26篇
  1993年   37篇
  1992年   14篇
  1991年   11篇
  1990年   15篇
  1989年   15篇
  1988年   13篇
  1987年   8篇
  1986年   9篇
  1985年   18篇
  1984年   9篇
  1982年   12篇
  1981年   7篇
  1980年   11篇
  1979年   3篇
  1978年   11篇
  1977年   6篇
  1976年   17篇
  1975年   7篇
  1973年   4篇
  1965年   2篇
排序方式: 共有1580条查询结果,搜索用时 15 毫秒
81.
Gene expression profiling data from DNA microarray were analyzed using the fuzzy neural network (FNN) modeling method for predicting the distant metastases of breast cancer. The best model consisting of five genes was able to predict metastases of breast cancer with 94% accuracy. Furthermore, 100% accuracy was achieved by majoritarian decision using only 25 genes from five noninferior models which were constructed independently. From the constructed model, gene expression rules, which may cause distant metastases, were explicitly extracted and 60% of the metastases cases could be explained by this rule. The FNN modeling method described in this paper enables precise extraction of significant biological markers affecting prognosis without prior knowledge.  相似文献   
82.
The fluorogenic derivatization reagents with a positive charge, 4-(dimethylaminoethylaminosulfonyl)-7-chloro-2,1,3-benzoxadiazole (DAABD-Cl) and 7-chloro-2,1,3-benzoxadiazole-4-sulfonylaminoethyltrimethylammonium chloride (TAABD-Cl), are proposed for use in proteomics studies. Following derivatization of protein mixtures with these reagents, a series of standard processes of isolation, digestion, and identification of the proteins were performed utilizing high-performance liquid chromatography-fluorescence detection and tandem mass spectrometry with the probability-based protein identification algorithm. Both DAABD and TAABD derivatives were detected fluorometrically at the femtomole level and showed more than 100-fold improvement in sensitivity compared to the underivatized original compounds with an electrospray ionization ion trap mass spectrometer analysis. The modification of the MASCOT database search system memorized with the fragment information of a DAABD-attached Cys residue allowed the identification of the proteolytic peptide fragments of the derivatized bovine serum albumin (BSA) with an estimated 38% sequence coverage of BSA. Utilizing DAABD-Cl as a derivatization reagent, identification of several proteins was also possible in a soluble extract of Caenorhabditis elegans (10 microg of protein). Consequently, for identification of proteins in the complex matrixes of proteins, DAABD-Cl could be a more appropriate reagent than ammonium 7-fluoro-2,1,3-benzoxadiazole-4-sulfonate as reported previously.  相似文献   
83.
Recently, a biologically inspired, bipedal, dynamic, humanoid robot was developed at the Artificial Life and Robotics Laboratory of Oita University. This bipedal humanoid robot is able to walk dynamically and to go up and down stairs. The central pattern generator developed produces various types of walking pattern. This robot has a pair of small CMOS color CCD cameras, a speaker, and a microphone in the head part, and will have a GPS, a portable telephone, and other sensors in the body part, so that the integration of locomotion and behavior to achieve specific demonstrations will be realized. This project develops dynamic mobility and the ability for autonomous recognition and navigation using the biological central nervous system, the brain system, and the real-time control system. Also, the design principles that demonstrate the dynamic interaction between neural and mechanical controls will be clarified. In Phase I, the platform of a small, bipedal, humanoid robot is used to develop autonomous locomotion and autonomous sensing and navigation. In Phase II of the project, an iteration on the platform design for human-size, bipedal, humanoid robots will be performed for operational testing. The development of bipedal humanoid robots that capture biological systems with unique principles and practices could dramatically increase their performance in tasks for national security needs.This work was presented in part at the 8th International Symposium on Artificial Life and Robotics, Oita, Japan, January 24–26, 2003  相似文献   
84.
85.
The attenuated total reflectance infrared (ATR-IR) spectra of several aqueous solutions have been measured by using a newly developed heatable rod-type ATR cell. The OH stretching bands showed systematic change with increasing solute concentrations and these changes can be explained by four different OH components based on curve-fitting results. NaCl solutions show longer H-bond distance character, while carbonate solutions present shorter ones. The Na2CO3 1 M solution conserves this shorter H-bond nature up to 100 degrees C. On the other hand, the loose nature of NaCl solutions becomes less pronounced at higher temperatures because of the dissociation of pure water clusters. These in situ observations of water structures are generally in agreement with the expected nature of fluids within the earth.  相似文献   
86.
Confocal Raman spectroscopy and confocal scanning laser microscopy have been used to analyze ligand distributions within individual chromatographic adsorbent particles. Three different types of particles have been investigated. The first type was synthesized to have a uniform distribution of allyl groups, whereas the two others were designed to have a surface layer of sulphopropyl groups and cores containing allyl groups and dextran, respectively. With confocal Raman spectroscopy it was possible to follow the distribution of both the surface layer and the interior. The distribution of sulphopropyl groups was evaluated with both confocal scanning laser microscopy and confocal Raman spectroscopy, whereas the distributions of allyl groups and dextran were evaluated only with the latter method. The results from the confocal measurements showed the expected result with a uniform distribution of allyl groups in the first type of particle and surface layers of sulphopropyl groups and cores with dextran or allyl groups for the two others.  相似文献   
87.
Abstract— Color displays and flexible displays that use electronic liquid powder have been developed. Novel types of color displays using either a colored powder or a color filter are discussed. We have also developed a flexible display with low‐cost substrate films with a high‐throughput roll‐to‐roll manufacturing method. These technologies enable a QR‐LPD to be widely used as an electronic‐paper display.  相似文献   
88.
Optical tweezers are powerful tools for manipulating single DNA molecules using fluorescence microscopy, particularly in nanotechnology‐based DNA analysis. We previously proposed a manipulation technique using microstructures driven by optical tweezers that allows the handling of single giant DNA molecules of millimetre length that cannot be manipulated by conventional techniques. To further develop this technique, the authors characterised the microstructures quantitatively from the view point of fabrication and efficiency of DNA manipulation under a fluorescence microscope. The success rate and precision of the fabrications were evaluated. The results indicate that the microstructures are obtained in an aqueous solution with a precision ∼50 nm at concentrations in the order of 106 particles/ml. The visibility of these microstructures under a fluorescence microscope was also characterised, along with the elucidation of the fabrication parameters needed to fine tune visibility. Manipulating yeast chromosomal DNA molecules with the microstructures illustrated the relationship between the efficiency of manipulation and the geometrical shape of the microstructure. This report provides the guidelines for designing microstructures used in single DNA molecule analysis based on on‐site DNA manipulation, and is expected to broaden the applications of this technique in the future.Inspec keywords: DNA, molecular biophysics, fluorescence, optical microscopy, radiation pressure, biological techniquesOther keywords: optically driven microstructures, single DNA molecule analysis, fluorescence microscopy, optical tweezers, nanotechnology‐based DNA analysis, manipulation technique, aqueous solution, fine tune visibility, yeast chromosomal DNA molecules, geometrical shape, on‐site DNA manipulation  相似文献   
89.
Using data from developing countries, this paper examines the links between ICT diffusion and per capita income, trade and financial indicators, education, and freedom indicators. Internet hosts, Internet users, personal computers and mobile phones represent indicators of ICT. The Gompertz model of technology diffusion is used to study ICT dissemination. The results show that income and government trade policies influence ICT diffusion. However, freedom indices may or may not affect ICT diffusion. Moreover, only personal computers and Internet hosts seem to have a positive association with income. Contrary to expectations, ICT diffusion is not associated with education.  相似文献   
90.
红山水库位于处于水磨河的出山口处,是阜康市的一座以灌溉和防洪为主的综合性拦河骨干水库工程,通过收集相邻流域水文站的资料运用地区洪峰流量模比系数综合频率曲线法计算不同频率设计洪峰流量,运用适线法计算不同频率设计洪量。  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