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   483篇
  免费   20篇
  国内免费   3篇
电工技术   2篇
综合类   3篇
化学工业   74篇
金属工艺   12篇
机械仪表   25篇
建筑科学   20篇
矿业工程   1篇
能源动力   27篇
轻工业   45篇
水利工程   7篇
石油天然气   6篇
无线电   63篇
一般工业技术   118篇
冶金工业   17篇
原子能技术   2篇
自动化技术   84篇
  2024年   4篇
  2023年   13篇
  2022年   34篇
  2021年   46篇
  2020年   24篇
  2019年   33篇
  2018年   41篇
  2017年   32篇
  2016年   39篇
  2015年   12篇
  2014年   21篇
  2013年   34篇
  2012年   27篇
  2011年   31篇
  2010年   21篇
  2009年   11篇
  2008年   10篇
  2007年   7篇
  2006年   5篇
  2005年   5篇
  2004年   5篇
  2003年   5篇
  2002年   8篇
  2001年   4篇
  2000年   3篇
  1998年   4篇
  1997年   4篇
  1996年   3篇
  1995年   4篇
  1994年   1篇
  1993年   3篇
  1992年   6篇
  1991年   3篇
  1989年   2篇
  1987年   1篇
排序方式: 共有506条查询结果,搜索用时 15 毫秒
1.
Shabir  Muhammad Yasir  Ullah  Ata  Mahmood  Zahid 《Wireless Networks》2019,25(8):5137-5150
Wireless Networks - Wireless sensor network (WSN) consists of small sized devices containing different sensors to monitor physical, environmental and medical conditions during surveillance of...  相似文献   
2.
In this paper, cenosphere particles embedded in AA2014 aluminium matrix are used to fabricate syntactic foam by stir casting method. The particle size is about 100?µm and foam density is about 1990?kg?m?3. Compression tests at strain rate 0.001/s are performed on foam samples to characterise their mechanical properties which are then used in numerical analysis on commercial finite element analysis software ABAQUS/CAE with isotropic elastic-plastic material model. Experimental and numerical results show good conformity in deformation behaviour with elastic and plateau zones showing average deviations less than 5% and 20%, respectively. Foams showed high yield stress and energy absorption capabilities that can be useful in making blast and impact resistant structures.  相似文献   
3.
Clean Technologies and Environmental Policy - The concentration of any disinfectant is a major parameter which is used to evaluate the quality of water. Chlorine is the most common disinfecting...  相似文献   
4.
Conducting poly(aniline‐co‐o‐anisidine) (PAS) films with different ratios of aniline units in the polymer chain were prepared by oxidative polymerization of different molar ratios of aniline and o‐anisidine in 1 M HCl using cyclic voltammetry. Due to the much higher reactivity of o‐anisidine, the structure and properties of PASs were found to be dominated by the o‐anisidine units. The polymerization of poly‐o‐anisidine and PASs followed zero‐order kinetics with respect to formation of the polymer (film thickness) and the autocatalytic polymerization of aniline was completely inhibited. In contrast to polyaniline, a decrease in the polymerization temperature was found to increase the amount of copolymer formed and its redox charge. The presence of aniline units in PASs led to a pronounced increase in the molecular weight and conductivity, and a decrease in the solubility in organic solvents. Repetitive charging/discharging cycles showed that PASs resist degradation more than polyaniline. Copyright © 2003 Society of Chemical Industry  相似文献   
5.
Water extracts from leaves of date palm, phoenix dactylifera, henna, Lawsonia inermis, and corn, Zea mays, were tested as corrosion inhibitors for steel, aluminum, copper and brass in acid chloride and sodium hydroxide solutions using weight loss, solution analysis and potential measurements. The inhibition action was found to critically depend on metal type and solution composition. Only, date palm and henna extracts were found highly effective in reducing corrosion rate of steel in acid chloride solutions and aluminum in sodium hydroxide solutions. The inhibition efficiency increased with increasing the concentration of the extract. The inhibition was interpreted in terms of chemisorption of some active ingredients in the leaves according to Temkin isotherm.  相似文献   
6.
Tumor size and prognosis in aggressively treated osteosarcoma   总被引:1,自引:0,他引:1  
PURPOSE: The aim of this retrospective analysis was to investigate the prognostic significance and optimal measures of tumor size in osteosarcoma treated with intensive neoadjuvant chemotherapy. PATIENTS AND METHODS: Initial anterior-posterior (AP) and lateral x-ray films of 128 patients treated within the trials Cooperative Osteosarcoma Study (COSS)-80, -82, and -86, were evaluated for the following three tumor diameters: length, width, and depth. Metastasis-free survival (MFS) analyses were performed in univariate and multivariate models with one, two, and three dimensions of the tumor as absolute or relative measures (tumor length, referred to bone length, plane and volume to body-surface area). RESULTS: Univariate analyses of MFS showed a high prognostic significance of all absolute measures. Relative measures, at best, showed a comparable predictive value. Cox regression analysis indicated the high prognostic significance of absolute tumor volume (ATV; P < .0001) and histologic response (P < .0001). None of 19 patients with an ATV < or = 70 cm3 and only four of 53 with an ATV < or = 150 cm3 relapsed, while in patients with an ATV more than 150 cm3, the relapse rate remained 40% to 60%, irrespective of further increase in volume. CONCLUSION: Initial tumor size is an important and easily obtainable prognostic factor in osteosarcoma and may serve as a basis for risk-adapted therapy. It is best represented by the absolute three-dimensional measure ATV. There is a cut-off point regarding the incidence of metastases at a tumor volume of approximately 150 cm3 as calculated from two-plane x-ray films.  相似文献   
7.
Cellulose nanocrystals (CNCs) incorporated with silver nanoparticles (AgNPs) photonic films have drawn considerable attention due to their plasmonic chiroptical activity. However, the exploitation of some fundamental properties for practical use such as the affinity analysis of metal nanoparticles attached to the surface of photonic films according to the solvent compatibility and antibacterial activity under physical conditions has yet not been studied. Hence, a facile process of in situ deposition of AgNPs into the chiral structure of CNC films is proposed. CNC photonic films, cross-linked by glutaraldehyde are prepared. This interaction generated the solvents-stable photonic film with a considerable amount of unreacted aldehyde functional groups that facilitates the reduction of Ag salt to AgNPs. The formed AgNPs in the photonic films show excellent stability over immersion in various polar and non-polar solvents. The post-solvent treated photonic films display excellent contact-based antibacterial behavior against gram-negative Escherichia coli.  相似文献   
8.
Ahmed A  Rehan M  Iqbal N 《ISA transactions》2011,50(2):249-255
This paper proposes the design of anti-windup compensator gain for stability of actuator input constrained state delay systems using constrained pole-position of the closed-loop. Based on Delay-Dependent Lyapunov-Krasovskii functionals and local sector conditions, a new LMI characterization is derived that ensures closed-loop asymptotic stability of constrained state delay systems while accounting upper bound fixed state delay and largest lower bound of the system’s pole-position in the formulation of anti-windup gain. Besides, at saturation, the method significantly nullifies the inherent slow dynamics present in the system. It is shown in the comparative numerical examples that the LMI formulation draws stability with improved time-domain performance.  相似文献   
9.
This paper investigates a local observer-based leader-following consensus control of one-sided Lipschitz (OSL) multi-agent systems (MASs) under input saturation. The proposed consensus control scheme has been formulated by using the OSL property, input saturation, directed graphs, estimated states, and quadratic inner-boundedness condition by attaining the regional stability. It is assumed that the graph always includes a (directed) spanning tree with respect to the leader root to develop matrix inequalities for investigating parameters of the proposed observer and consensus protocols. Further, a new observer-based consensus tracking method for MASs with saturation, concerning independent topologies for communicating outputs and estimates over the network, is explored to deal with a more perplexing and realistic situation. In contrast to the traditional methods, the proposed consensus approach considers output feedback and deals with the input saturation for a generalized class of nonlinear systems. The efficiency of the obtained results is illustrated via application to a group of five moving agents in the Cartesian coordinates.  相似文献   
10.
Knowledge and Information Systems - Collaborative filtering suffers from the issues of data sparsity and cold start. Due to which recommendation models that only rely on the user–item...  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