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   993篇
  免费   21篇
  国内免费   2篇
电工技术   18篇
综合类   1篇
化学工业   236篇
金属工艺   26篇
机械仪表   23篇
建筑科学   32篇
能源动力   39篇
轻工业   59篇
水利工程   3篇
石油天然气   1篇
无线电   130篇
一般工业技术   204篇
冶金工业   88篇
原子能技术   3篇
自动化技术   153篇
  2022年   19篇
  2021年   34篇
  2020年   25篇
  2019年   23篇
  2018年   28篇
  2017年   25篇
  2016年   15篇
  2015年   15篇
  2014年   23篇
  2013年   76篇
  2012年   42篇
  2011年   45篇
  2010年   45篇
  2009年   38篇
  2008年   54篇
  2007年   34篇
  2006年   28篇
  2005年   31篇
  2004年   26篇
  2003年   16篇
  2002年   18篇
  2000年   6篇
  1999年   11篇
  1998年   28篇
  1997年   21篇
  1996年   13篇
  1995年   12篇
  1994年   10篇
  1993年   8篇
  1992年   9篇
  1991年   12篇
  1990年   14篇
  1989年   8篇
  1988年   16篇
  1987年   8篇
  1986年   7篇
  1985年   6篇
  1984年   15篇
  1983年   14篇
  1982年   11篇
  1981年   7篇
  1980年   11篇
  1979年   12篇
  1978年   8篇
  1977年   6篇
  1976年   19篇
  1975年   12篇
  1974年   8篇
  1973年   6篇
  1971年   8篇
排序方式: 共有1016条查询结果,搜索用时 0 毫秒
101.
This paper discusses the iterative provision of modelling insights on long-term decarbonisation scenarios for UK energy policy makers. A multi-year model construction process of the UK MARKAL-Macro-hybrid energy-economic model, and four subsequent major policy analyses illustrates the scope of this interaction. The initial set of modelling runs focused on the technical feasibility of long-term 60% carbon dioxide (CO2) reduction scenarios, the role of key technologies, and the underlying uncertainties. Furthermore subsequent modelling studies were aimed to generate insights on more stringent targets, and on issues and uncertainties that may make targets harder to achieve. Hence, this paper analyses the large number of long-term UK CO2 reduction scenarios through a clustering approach on target stringency and barriers to implementation. Robust findings and key uncertainties are highlighted, including the critical role of the power sector, trade-offs between resources, sectors, key energy technologies and behavioural responses, and the increasing level and spread of CO2 marginal prices and GDP impacts. The relevance and use of modelling insights to the UK energy policy process is shown in the continuation of the energy modelling–policy interface. This constitutes both ongoing model development, and nuanced scenario analysis designed to further explore key uncertainties in evolving policy issues.  相似文献   
102.
Large software systems, developed over several years, are the backbone of industries such as banking, retail, transportation, and telecommunications. With multiple bug fixes and feature enhancements, these systems gradually deviate from the intended architecture and deteriorate into unmanageable monoliths. This article presents a case study of a banking application besot with such problems and the modularization approach that the company adopted as a solution. It also highlights benefits unearthed as a result of this reengineering exercise.  相似文献   
103.
104.
105.
106.
The photoinitiated bulk polymerization process, which has been used recently in the manufacture of solid optical diffraction filters, is examined to understand the dynamics of both the crystalline colloidal arrays (CCA) and the host monomer species. Our analysis indicates that volume shrinkage of the monomer, changes in the dielectric properties of the monomer, and inhomogeneities of polymerization reaction rate across the dispersion during the polymerization process, are the major contributors for observed lattice compression and lattice disorder of the CCA of silica spheres in polymerized acrylic/methacrylic ester films. The effect of orientation of photocell with respect to the radiation source on Bragg diffraction of CCA indicated the presence of convective stirring in the thin fluid system during the photopolymerization that deleteriously affects the periodic array structures. To devise reproducible and more efficient optical filters, experimental methods to minimize or eliminate convective instabilities in monomeric dispersions during polymerization are suggested. © 1998 Chapman & Hall  相似文献   
107.
Normal Portland cement mortar discs containing precipitated or ground limestone at dosages of 0, 2.5, 5 and 15% were made at water/cement ratios of 0.42 or 0.60. They were hydrated in lime water or sea water solution for periods up to 1 year. The length and modulus of elasticity changes were monitored periodically. Some mortars containing CaCO3 exhibited more than three times the expansion of the reference in sea water. The expansions were greater in samples containing fine CaCO3. The modulus of elasticity was especially low for samples containing precipitated CaCO3 and exposed to sea water.  相似文献   
108.
Origin of room-temperature ferromagnetism in cobalt-doped ZnO   总被引:1,自引:0,他引:1  
Thin films of ZnO doped with cobalt have been grown by the pulsed laser deposition (PLD) technique in different temperatures ranging from 500°C to 650°C. The films grown on sapphire c-plane single crystal were found to be highly epitaxial. Magnetic properties of these films were studied, and the films exhibited ferromagnetic characteristics at room temperature. Detailed structural and microstructural characterization was performed to correlate the fate of the magnetic impurities, i.e., cobalt, and the cause of magnetic properties. It is established from this work that the magnetic properties of these films are inherent to the system, and any presence of second phase/nanoclusters/precipitates are ruled out as the cause of magnetic properties. The techniques used to establish these were conventional and high-resolution transmission electron microscopy (HRTEM) along with electron-energy loss spectroscopy (EELS) and scanning transmission electron microscopy-atomic number (STEM-Z) contrast studies.  相似文献   
109.
110.
The second in the Niagara series of processors (Niagara2) from Sun Microsystems is based on the power-efficient chip multi-threading (CMT) architecture optimized for Space, Watts (Power), and Performance (SWaP) [SWap Rating = Performance/(Space * Power) ]. It doubles the throughput performance and performance/watt, and provides >10times improvement in floating point throughput performance as compared to UltraSPARC T1 (Niagara1). There are two 10 Gb Ethernet ports on chip. Niagara2 has eight SPARC cores, each supporting concurrent execution of eight threads for 64 threads total. Each SPARC core has a floating point and graphics unit and an advanced cryptographic unit which provides high enough bandwidth to run the two 10 Gb Ethernet ports encrypted at wire speeds. There is a 4 MB Level2 cache on chip. Each of the four on-chip memory controllers controls two FBDIMM channels. Niagara2 has 503 million transistors on a 342 mm2 die packaged in a flip-chip glass ceramic package with 1831 pins. The chip is built in Texas Instruments' 65 nm 11LM triple-Vt CMOS process. It operates at 1.4 GHz at 1.1 V and consumes 84 W.  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