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   929篇
  免费   32篇
  国内免费   5篇
电工技术   7篇
化学工业   173篇
金属工艺   34篇
机械仪表   14篇
建筑科学   21篇
矿业工程   2篇
能源动力   51篇
轻工业   46篇
水利工程   4篇
石油天然气   1篇
无线电   119篇
一般工业技术   235篇
冶金工业   91篇
原子能技术   28篇
自动化技术   140篇
  2023年   10篇
  2022年   29篇
  2021年   45篇
  2020年   45篇
  2019年   35篇
  2018年   53篇
  2017年   37篇
  2016年   27篇
  2015年   23篇
  2014年   31篇
  2013年   49篇
  2012年   37篇
  2011年   43篇
  2010年   27篇
  2009年   35篇
  2008年   29篇
  2007年   34篇
  2006年   19篇
  2005年   14篇
  2004年   10篇
  2003年   11篇
  2002年   14篇
  2001年   16篇
  2000年   17篇
  1999年   13篇
  1998年   24篇
  1997年   15篇
  1996年   21篇
  1995年   17篇
  1994年   16篇
  1993年   20篇
  1992年   11篇
  1991年   17篇
  1990年   16篇
  1989年   14篇
  1988年   10篇
  1987年   4篇
  1986年   12篇
  1985年   8篇
  1984年   5篇
  1983年   14篇
  1982年   9篇
  1980年   3篇
  1978年   4篇
  1977年   3篇
  1976年   3篇
  1975年   3篇
  1974年   3篇
  1973年   2篇
  1970年   2篇
排序方式: 共有966条查询结果,搜索用时 15 毫秒
951.
This article describes the inferential procedures and Bayesian optimal life-testing issues under Type-II unified hybrid censoring scheme. First, the explicit expressions of expected number of failures, expected duration of testing, and Fisher information matrix for the unknown parameters of the underlying lifetime model are derived. Then, using these quantities, the Bayesian optimal life-testing plans are computed in a subsequent section. A cost constraint D-optimal optimization problem has been formulated, and the corresponding solution algorithm is provided to obtain optimal plans. Computational procedures are illustrated through numerical examples.  相似文献   
952.
953.
Knowledge and Information Systems - In recent years, skin-related problems induce psychological problems and also injure physical health, particularly if the patient’s face was disfigured or...  相似文献   
954.
An amyloid-β inspired biocompatible short peptide amphiphile (sPA) molecule was used for controlled and targeted delivery of bioactive silver nanoparticles via transforming sPA nanostructures. Such sPA-AgNPs hybrid structures can be further used to develop antibacterial materials to combat emerging bacterial resistance. Due to the excellent antibacterial activity of silver, the growth of clinically relevant bacteria was inhibited in the presence of AgNPs-sPA hybrids. Bacterial tests demonstrated that the high biocompatibility and low cytotoxicity of the designed sPA allow it to work as a model drug delivery agent. It therefore shows great potential in locally addressing bacterial infections. The results of our study suggest that these nanodevices have the potential to trap and then engage in the facile delivery of their chemical payload at the target site, thereby working as potential delivery materials. This system has potential therapeutic value for the treatment of microbiota triggered progression of neurodegenerative diseases.  相似文献   
955.
The convective–radiative magnetohydrodynamic non-Newtonian second-grade fluid boundary layer flow from a curved stretching surface has been scrutinized in the present study. The Reiner–Rivlin second-grade viscoelastic model is deployed which provides a good approximation for certain magnetic polymers. High temperature invokes the presence of radiative heat transfer, which is simulated with the Rosseland diffusion approximation. Viscous dissipation and Joule heating are also featured in the model and hydrodynamic (velocity) slip at the wall is also incorporated in the boundary conditions. The emerging nonlinear coupled dimensionless transport equations are solved with a Runge–Kutta method and a shooting numerical scheme. The influence of emerging multiphysical flow parameters on the dimensionless profiles is examined with the help of plots for comparative analysis of both non-Newtonian fluid and Newtonian fluid. The numerical solutions are validated for special cases with existing works. The velocity declines for a higher magnetic field, whereas the reverse trend is noted for the temperature function. The augmentation in the thermal field is noted with increments in radiation parameters. Furthermore, the fluid temperature of the second-grade fluid is higher with increasing Brinkmann number. The wall slip induces deceleration. Contour plots for streamlines and isotherms are also visualized and analyzed.  相似文献   
956.
A comprehensive thermodynamic study was conducted to evaluate the comparative efficacy of methanol and dimethyl ether (DME) synthesis using CO2 rich syngas feed. The first part of our study included assessing the relative performances of the methanol synthesis system, two step DME synthesis system, and one step DME synthesis system in terms of the COx conversion and product yield (methanol/DME) based on the Gibbs free energy minimization approach. The wide range of composition of CO2-enriched syngas feed produced by the coal and biomass gasification was simulated using Aspen Plus and the following evaluation parameters were analyzed for a broad parameter range: reaction temperature (180–280°C), reaction pressure (10–80 bar), stoichiometry number (SN) (0–11), and CO2/(CO2 + CO) molar feed ratio (0–1) for isothermal as well as adiabatic conditions. Based on the equilibrium yield, one-step DME synthesis was discovered as the most viable process to utilize the co-gasification derived syngas effectively. In the second part of our study, the overall process efficiency was inspected through the process design of 1 tonnes per day (TPD) DME plant inclusive of heat integration, resulting in significant CO2 abatement and DME production with high product purity and minimum energy consumption. Consequently, one-step DME production via CO2-enriched syngas obtained through the coal or biomass gasification process is identified as the leading technology based on energy utilization and CO2 abatement.  相似文献   
957.
The paper describes the approach taken for configuration management in the Nexus distributed operating system. Nexus uses kernel-level support for monitoring the failure or termination status of distributed components of an application. Periodic user-level messages are not required for status monitoring. Group and dependency relationships between such components can be defined by the programmer for the purpose of configuration monitoring and management. An object belonging to a distributed application can be monitored by its host kernel for system-defined exception conditions. When any of these conditions arise, other objects are notified through signals or messages, as specified by the programmer.  相似文献   
958.
Journal of Inorganic and Organometallic Polymers and Materials - Metallopolymeric functional nanomaterials have been gained the significant interest of researchers because of their exclusive...  相似文献   
959.
Network topology is manipulated in free-radical copolymerization via proper selection of crosslinker type and its respective properties when paired with specific monomers. Our prior work has focused on the impact of the reduced reactivity parameter Ψ applied to a pendent vinyl, characteristic for each monomer/crosslinker pair, yet here we assess the relative importance of the comonomer reactivity ratios to see whether one factor can counterbalance the other. The traditional reactivity ratio determines when the crosslinker molecule is incorporated into the polymer backbone, while the reduced reactivity Ψ parameter relates to the efficiency of the resulting pendent side chain vinyl being utilized to form a crosslink node at some later point during the polymerization. Both factors are then contrasted with simply the overall loading of crosslinker. Either n-butyl methacrylate (n-BMA) or styrene (STY) was chosen as a primary backbone monomer to copolymerize with one of three crosslinkers: 1,4-butanediol dimethacylate (BDDMA), 1,4-butanediol diacrylate (BDDA), or divinylbenzene (DVB). Both kinetics and gel can be most dramatically boosted when a crosslinker is applied having a reactivity ratio favouring early insertion. This in turn leads to an earlier onset of gel formation, which ultimately results in greater final gel content. This amplification of both kinetics and gel can overcome an otherwise small Ψ due to crosslinker or main monomer choice. This reactivity ratio effect was further confirmed by Monte Carlo simulations. By whatever mechanism (higher Ψ, lower rA, or higher crosslinker level), earlier onset of gelation produces more gel overall and a tighter network topology.  相似文献   
960.
The microbiota-gut-brain axis (GBA) plays a critical role in the development of neurodegenerative diseases. Dysbiosis of the intestinal microbiome causes a significant alteration in the gut microbiota of Alzheimer's disease (AD) patients, followed by neuroinflammatory processes. Thus, AD beginning in the gut is closely related to an imbalance in gut microbiota, and hence a multidomain approach to reduce this imbalance by exerting positive effects on the gut microbiota is needed. In one example, a tyrosine-based short peptide amphiphile (sPA) was used to synthesize antibacterial AgNPs−sPA nanostructures. Such nanostructures showed high biocompatibility and low cytotoxicity, and therefore work as model drug delivery agents for addressing local bacterial infections. These may have therapeutic value for the treatment of microbiota-triggered progression of neurodegenerative diseases.  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