全文获取类型
收费全文 | 2713篇 |
免费 | 139篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 25篇 |
综合类 | 3篇 |
化学工业 | 703篇 |
金属工艺 | 69篇 |
机械仪表 | 64篇 |
建筑科学 | 84篇 |
矿业工程 | 6篇 |
能源动力 | 118篇 |
轻工业 | 261篇 |
水利工程 | 38篇 |
石油天然气 | 11篇 |
无线电 | 200篇 |
一般工业技术 | 459篇 |
冶金工业 | 256篇 |
原子能技术 | 20篇 |
自动化技术 | 545篇 |
出版年
2023年 | 32篇 |
2022年 | 82篇 |
2021年 | 125篇 |
2020年 | 87篇 |
2019年 | 70篇 |
2018年 | 78篇 |
2017年 | 92篇 |
2016年 | 94篇 |
2015年 | 86篇 |
2014年 | 89篇 |
2013年 | 213篇 |
2012年 | 197篇 |
2011年 | 196篇 |
2010年 | 124篇 |
2009年 | 157篇 |
2008年 | 119篇 |
2007年 | 118篇 |
2006年 | 102篇 |
2005年 | 86篇 |
2004年 | 71篇 |
2003年 | 54篇 |
2002年 | 60篇 |
2001年 | 37篇 |
2000年 | 25篇 |
1999年 | 34篇 |
1998年 | 65篇 |
1997年 | 49篇 |
1996年 | 34篇 |
1995年 | 23篇 |
1994年 | 17篇 |
1993年 | 23篇 |
1992年 | 8篇 |
1991年 | 15篇 |
1990年 | 12篇 |
1989年 | 20篇 |
1988年 | 10篇 |
1987年 | 15篇 |
1986年 | 15篇 |
1985年 | 10篇 |
1984年 | 13篇 |
1983年 | 10篇 |
1982年 | 5篇 |
1981年 | 9篇 |
1980年 | 18篇 |
1977年 | 4篇 |
1976年 | 10篇 |
1975年 | 5篇 |
1974年 | 7篇 |
1973年 | 4篇 |
1972年 | 5篇 |
排序方式: 共有2862条查询结果,搜索用时 603 毫秒
61.
Dilute copper-aluminium alloys were oxidized in air from 700 to 1000 °C. Two distinctive behaviours were observed: alloys with at least 3 wt% aluminium showed excellent oxidation resistance in the whole temperature range. Alloys with 2 wt% or less aluminium exhibited good oxidation resistance up to 800 °C; but as the temperature was further increased, the oxidation rate of these alloys increased and became comparable to that of pure copper. A kinetic model was developed to explain the oxidation behaviour and indirectly determine the amount of dissolved oxygen in the alloys tested. It was found that the oxygen dissolved in alloys with up to 2 wt% Al exceeded its solubility limit in copper, whereas the dissolved oxygen in alloys with higher aluminium contents was below the solubility limit. This difference may account for the significantly different oxidation resistance. 相似文献
62.
This work presents new stabilised finite element methods for a bending moments formulation of the Reissner-Mindlin plate model. The introduction of the bending moment as an extra unknown leads to a new weak formulation, where the symmetry of this variable is imposed strongly in the space. This weak problem is proved to be well-posed, and stabilised Galerkin schemes for its discretisation are presented and analysed. The finite element methods are such that the bending moment tensor is sought in a finite element space constituted of piecewise linear continuos and symmetric tensors. Optimal error estimates are proved, and these findings are illustrated by representative numerical experiments. 相似文献
63.
64.
Saeed Salah Gabriel Maciá-Fernández Jesús E. Díaz-Verdejo Leovigildo Sánchez-Casado 《Journal of Network and Systems Management》2016,24(1):57-91
In Information Technology Service Management (ITSM), network management teams typically use an Incident Ticket System (ITS) as a tool to track, troubleshoot, and coordinate the resolution of network incidents that occur during the daily operation of the network. A well organized ITS may positively impact on the efficiency of the incident management process. Nevertheless, in many cases the handling of tickets by the management team is not completely systematic and may be incoherent and inefficient. This way, irrelevant or redundant tickets for the same incident may be issued, thus creating a redundancy in the system that leads to inefficiencies. In this paper, we suggest a model aimed to correlate redundant tickets in order to reduce the information to a single ticket per incident. We validate the proposed correlation model by evaluating it with two datasets taken from a real ticketing system of a telecommunications network company. Using this model as a basis, we also develop and evaluate a methodology that assesses the efficiency of the management team during the process of tickets creation and management. Based on it, we also get some insights on the performance of the different management groups involved in the ticket creation process. These analyses can be leveraged for improving both the management groups functioning and the policies for the tickets’ creation. 相似文献
65.
66.
Peter Frolkovič Michael Lampe Gabriel Wittum 《Computing and Visualization in Science》2016,18(1):17-29
When a realistic modelling of radioactive contaminant transport in flowing groundwater is required, very large systems of coupled partial and ordinary differential equations can arise that have to be solved numerically. For that purpose, the software package \(r^3t\) is developed in which several advanced numerical methods are implemented to solve such models efficiently and accurately. Using software tools of \(r^3t\) one can treat successfully nontrivial mathematical problems like advection-dominated system with different retardation of transport for each component and with nonlinear Freundlich sorption and/or precipitation. Additionally, long time simulations on complex 3D geological domains using unstructured grids can be realized. In this paper we introduce and summarize the most important and novel features of numerical simulation for radioactive contaminant transport in porous media when using \(r^3t\). 相似文献
67.
Differential protein abundance in promastigotes of nitric oxide‐sensitive and resistant Leishmania chagasi strains
下载免费PDF全文
![点击此处可从《Proteomics. Clinical applications》网站下载免费的PDF全文](/ch/ext_images/free.gif)
68.
As telecommunication networks evolve rapidly in terms of scalability, complexity, and heterogeneity, the efficiency of fault localization procedures and the accuracy in the detection of anomalous behaviors are becoming important factors that largely influence the decision making process in large management companies. For this reason, telecommunication companies are doing a big effort investing in new technologies and projects aimed at finding efficient management solutions. One of the challenging issues for network and system management operators is that of dealing with the huge amount of alerts generated by the managed systems and networks. In order to discover anomalous behaviors and speed up fault localization processes, alert correlation is one of the most popular resources. Although many different alert correlation techniques have been investigated, it is still an active research field. In this paper, a survey of the state of the art in alert correlation techniques is presented. Unlike other authors, we consider that the correlation process is a common problem for different fields in the industry. Thus, we focus on showing the broad influence of this problem. Additionally, we suggest an alert correlation architecture capable of modeling current and prospective proposals. Finally, we also review some of the most important commercial products currently available. 相似文献
69.
Christoph Spengler Marcus Huber Andreas Gabriel Beatrix C. Hiesmayr 《Quantum Information Processing》2013,12(1):269-278
Entanglement in high-dimensional many-body systems plays an increasingly vital role in the foundations and applications of quantum physics. In the present paper, we introduce a theoretical concept which allows to categorize multipartite states by the number of degrees of freedom being entangled. In this regard, we derive computable and experimentally friendly criteria for arbitrary multipartite qudit systems that enable to examine in how many degrees of freedom a mixed state is genuine multipartite entangled. 相似文献
70.
A very important class of inverse problems are those modelled by integral equations of the first kind. These equations are usually ill-conditioned, such that any discretization technique will produce an ill-conditioned system, in classical or least-squares formulation. For such kind of symmetric problems, we propose in this paper a stable iterative solver based on an approximate orthogonalization algorithm introduced by Z. Kovarik. We prove convergence of our algorithm for general symmetric least-squares problems and present some numerical experiments ilustrating its good behaviour on problems concerned with the determination of charge distribution generating a given electric field and gravity surveying, both modelled by first kind integral equations. 相似文献