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   1275篇
  免费   59篇
电工技术   10篇
综合类   1篇
化学工业   304篇
金属工艺   30篇
机械仪表   34篇
建筑科学   43篇
矿业工程   2篇
能源动力   60篇
轻工业   101篇
水利工程   6篇
石油天然气   6篇
无线电   125篇
一般工业技术   275篇
冶金工业   98篇
原子能技术   11篇
自动化技术   228篇
  2023年   8篇
  2022年   5篇
  2021年   31篇
  2020年   25篇
  2019年   19篇
  2018年   22篇
  2017年   35篇
  2016年   38篇
  2015年   30篇
  2014年   39篇
  2013年   85篇
  2012年   77篇
  2011年   80篇
  2010年   69篇
  2009年   77篇
  2008年   77篇
  2007年   60篇
  2006年   64篇
  2005年   53篇
  2004年   40篇
  2003年   38篇
  2002年   32篇
  2001年   23篇
  2000年   14篇
  1999年   24篇
  1998年   34篇
  1997年   20篇
  1996年   18篇
  1995年   17篇
  1994年   16篇
  1993年   14篇
  1992年   9篇
  1991年   14篇
  1990年   12篇
  1989年   9篇
  1988年   6篇
  1987年   12篇
  1986年   9篇
  1985年   9篇
  1984年   5篇
  1983年   4篇
  1982年   7篇
  1981年   10篇
  1980年   5篇
  1979年   7篇
  1978年   5篇
  1977年   5篇
  1976年   4篇
  1975年   4篇
  1974年   4篇
排序方式: 共有1334条查询结果,搜索用时 31 毫秒
11.
Previous studies have shown that bizarre and common images produce equivalent levels of recall in unmixed-list designs. Using unmixed lists, we tested the view that bizarre images would be less susceptible than common images to common sources of interference. In all experiments, subjects imaged a list of either bizarre or common sentences and then performed some kind of interfering task before recalling the initial list of sentences. Experiment 1 showed that bizarre images were better accessed than common images after imaging an intervening list of common sentences. Also, components of common images tended to be better recalled than those of bizarre images after imaging an intervening list of bizarre sentences. Experiments 2a and 2b showed that interfering tasks consisting of studying lists of common concrete nouns did not differentially affect memory for bizarre and common images. In Experiment 3, labeling and imaging an interfering list of common pictures produced higher recall of bizarre images. Generally, bizarre images appeared to be less susceptible than common images to interference from certain types of common encodings. Importantly, the superior recall of bizarre images was always due to greater image (sentence) access, whereas higher recall of common images was associated with greater recovery of the image (sentence) constituents. Explanation of the precise pattern of results requires consideration of the distinctive properties of bizarre images. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
12.
13.
The elastic behavior of supported gold thin films has been studied using a framework in which the elastic interaction between grains and the actual structure of the film (i.e. preferential grain orientation and grain shape) are taken into account. Experiments were carried out using synchrotron X-ray diffraction combined with in-situ tensile testing and thereafter, no assumptions on the residual stress state and on the stress-free lattice parameter a0 have to be made. Modeling of grain elastic interactions is based on the extension of Eshelby-Kröner model, which allows for estimating the elastic behavior of polycrystals considering the texture and the shape of the crystallites. Flat-disc shaped grains arrangement is shown to yield the best representation of the elastic behavior of the fiber-textured gold thin films composed of columnar grains. This non-intuitive representation results from free-surface effect.  相似文献   
14.
第二代(2G)移动网络和传统的固定网络都提供了一套相对完整的话音业务。尽管智能网络(IN)技术使电信业务有所增强,但电信业务的发展仍然缓慢,而且样式基本保持不变。下一代网络(NGN)和第三代(3G)移动网络就是为了克服这些局限性而设计的,它们通过重组网络架构将业务同网络分离开来、将信息和电话技术融合起来并引进了会话初始协议(SIP)等开放协议。同时,它们还有望提供满足用户和运营商需求的新的增值业务。这些网络包括满足用户对业务期望所需的所有组成部分。NGN和3G就其服务能力而言有3个主要优点:首先,它们将信息世界和电话世界结…  相似文献   
15.
A new process of management of waste of composite materials from Sheet Moulding Compounds (SMC), as reinforcing fillers for thermoplastic materials, including both mechanical and chemical processes is proposed in this paper. Communited SMC being composed of coated glass fibres intimately mixed with calcium carbonate powder, their reinforcing power is low. First, the fibrous part was increased by partial dissolution of calcium carbonate present in the crushed products SMC. Second, a process of partial solvolysis was developed aiming at strong increasing the interfacial mechanical properties by functionalising of SMC load incorporated into polypropylene/grafted maleic anhydride polypropylene (PP/PPgma). At this effect, we investigated a treatment with a hot triamine (diethylenetriamine, DETA) in order to create a functionalisation, after scission of the bond ester of unsaturated polyester, as bridging amino-succinimide.The effect of this recycling way by partial solvolysis was checked from the mechanical properties of the resulting reinforced PP/PPgma material: Although a lower of Young modulus, better yield stress and especially resilience were observed.  相似文献   
16.
This paper presents the results of the Réseau futé (smart net) project, the goal of which is to use distributed AI and multi-agent techniques for network management and supervision. More precisely, these techniques have been applied to the partial automation of the dynamic processing (what is known about a network is always incomplete and can change at any time) of alarms and of various event notifications received by network management platforms. The system that we propose is able for example to automatically handle some alarms or to filter events of no-interest for a given operator. To achieve this goal, an assistant, or interface agent according to the model proposed by Patti Maes [MK93], has been realized. The goal of the assistant is first to learn, by observation, the behavior of the network supervision operator and second to reproduce such a behavior when the conditions in which the behavior has been learned are detected again. The learned information are stored using chronicles [Gha94]. A chronicle is a data-structure allowing programmers to represent sequences of events while taking temporal knowledge into account. Our assistant has been implemented and tested within Magenta which is a program, written in Smalltalk, that simulates (in a simplified way) a network management platform. This program respects roughly the gdmo and cmis standards.  相似文献   
17.
Past research has frequently failed to find age differences in prospective memory. This article tested the possibility that age differences would be more likely to emerge on a prospective memory task that was high in self-initiated retrieval. In the 1st experiment, participants were asked to perform an action every 10 min (a time-based task presumed to be high in self-initiated retrieval); in the 2nd experiment, participants were asked to perform an action whenever a particular word was presented (an event-based task presumed to be relatively low in self-initiated retrieval). Age differences were found with the time-based task but not with the event-based task. This pattern of age differences was again found in a 3rd experiment in which a new experimental procedure was used and the nature of the prospective memory task was directly varied. Generally, the results suggest that self-initiated retrieval processes are an important component of age-related differences across both retrospective and prospective memory tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
18.
The FcγRIIA/CD32A is mainly expressed on platelets, myeloid and several endothelial cells. Its affinity is considered insufficient for allowing significant binding of monomeric IgG, while its H131R polymorphism (histidine > arginine at position 131) influences affinity for multimeric IgG2. Platelet FcγRIIA has been reported to contribute to IgG-containing immune-complexe clearance. Given our finding that platelet FcγRIIA actually binds monomeric IgG, we investigated the role of platelets and FcγRIIA in IgG antibody elimination. We used pharmacokinetics analysis of infliximab (IgG1) in individuals with controlled Crohn’s disease. The influence of platelet count and FcγRIIA polymorphism was quantified by multivariate linear modelling. The infliximab half-life increased with R allele number (13.2, 14.4 and 15.6 days for HH, HR and RR patients, respectively). It decreased with increasing platelet count in R carriers: from ≈20 days (RR) and ≈17 days (HR) at 150 × 109/L, respectively, to ≈13 days (both HR and RR) at 350 × 109/L. Moreover, a flow cytometry assay showed that infliximab and monomeric IgG1 bound efficiently to platelet FcγRIIA H and R allotypes, whereas panitumumab and IgG2 bound poorly to the latter. We propose that infliximab (and presumably any IgG1 antibody) elimination is partly due to an unappreciated mechanism dependent on binding to platelet FcγRIIA, which is probably tuned by its affinity for IgG2.  相似文献   
19.
The main contribution of the present article consists of new 3D parallel and symmetric thinning schemes which have the following qualities:
  • They are effective and sound, in the sense that they are guaranteed to preserve topology. This guarantee is obtained thanks to a theorem on critical kernels;
  • They are powerful, in the sense that they remove more points, in one iteration, than any other symmetric parallel thinning scheme;
  • They are versatile, as conditions for the preservation of geometrical features (e.g., curve extremities or surface borders) are independent of those accounting for topology preservation;
  • They are efficient: we provide in this article a small set of masks, acting in the grid ?3, that is sufficient, in addition to the classical simple point test, to straightforwardly implement them.
  •   相似文献   
    20.
    This paper is concerned with the computation of the skeleton of a shape Ω included in ?2. We show some connections between the Euclidean distance function d to and the solution u of the Poisson problem Δu(x)=?1 if x is in Ω and u(x)=0 if x is on . This enables us to propose a new and fast algorithm to compute an approximation of the skeleton of . We illustrate the approach with some numerical experiments.  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