全文获取类型
收费全文 | 29774篇 |
免费 | 2159篇 |
国内免费 | 1867篇 |
专业分类
电工技术 | 925篇 |
技术理论 | 2篇 |
综合类 | 1778篇 |
化学工业 | 2064篇 |
金属工艺 | 733篇 |
机械仪表 | 1822篇 |
建筑科学 | 2009篇 |
矿业工程 | 422篇 |
能源动力 | 688篇 |
轻工业 | 880篇 |
水利工程 | 444篇 |
石油天然气 | 400篇 |
武器工业 | 296篇 |
无线电 | 2773篇 |
一般工业技术 | 2824篇 |
冶金工业 | 933篇 |
原子能技术 | 494篇 |
自动化技术 | 14313篇 |
出版年
2024年 | 83篇 |
2023年 | 477篇 |
2022年 | 654篇 |
2021年 | 920篇 |
2020年 | 829篇 |
2019年 | 686篇 |
2018年 | 701篇 |
2017年 | 867篇 |
2016年 | 945篇 |
2015年 | 903篇 |
2014年 | 1633篇 |
2013年 | 1647篇 |
2012年 | 1672篇 |
2011年 | 2059篇 |
2010年 | 1399篇 |
2009年 | 1531篇 |
2008年 | 1690篇 |
2007年 | 1998篇 |
2006年 | 1838篇 |
2005年 | 1789篇 |
2004年 | 1566篇 |
2003年 | 1453篇 |
2002年 | 1146篇 |
2001年 | 888篇 |
2000年 | 724篇 |
1999年 | 633篇 |
1998年 | 483篇 |
1997年 | 385篇 |
1996年 | 344篇 |
1995年 | 336篇 |
1994年 | 230篇 |
1993年 | 188篇 |
1992年 | 141篇 |
1991年 | 118篇 |
1990年 | 115篇 |
1989年 | 111篇 |
1988年 | 99篇 |
1987年 | 58篇 |
1986年 | 46篇 |
1985年 | 58篇 |
1984年 | 50篇 |
1983年 | 45篇 |
1982年 | 36篇 |
1981年 | 28篇 |
1980年 | 26篇 |
1979年 | 21篇 |
1978年 | 20篇 |
1977年 | 15篇 |
1976年 | 31篇 |
1975年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
The veracity present in molecular data available in biological databases possesses new challenges for data analytics. The analysis of molecular data of various diseases can provide vital information for developing better understanding of the molecular mechanism of a disease. In this paper, an attempt has been made to propose a model that addresses the issue of veracity in data analytics for amino acid association patterns in protein sequences of Swine Influenza Virus. The veracity is caused by intra-sequential and inter-sequential biases present in the sequences due to varying degrees of relationships among amino acids. A complete dataset of 63,682 protein sequences is downloaded from NCBI and is refined. The refined dataset consists of 26,594 sequences which are employed in the present study. The type I fuzzy set is employed to explore amino acid association patterns in the dataset. The type I fuzzy support is refined to partially remove the inter-sequential biases causing veracity in data. The remaining inter-sequential biases present in refined fuzzy support are evaluated and eliminated using type II fuzzy set. Hence, it is concluded that a combination of type II fuzzy & refined fuzzy approach is the optimal approach for extracting a better picture of amino acid association patterns in the molecular dataset. 相似文献
33.
Daniel H. Stones Anne-Marie Krachler 《International journal of molecular sciences》2015,16(2):2626-2640
The ability of bacterial species to colonize and infect host organisms is critically dependent upon their capacity to adhere to cellular surfaces of the host. Adherence to cell surfaces is known to be essential for the activation and delivery of certain virulence factors, but can also directly affect host cell signaling to aid bacterial spread and survival. In this review we will discuss the recent advances in the field of bacterial adhesion, how we are beginning to unravel the effects adhesins have on host cell signaling, and how these changes aid the bacteria in terms of their survival and evasion of immune responses. Finally, we will highlight how the exploitation of bacterial adhesins may provide new therapeutic avenues for the treatment of a wide range of bacterial infections. 相似文献
34.
The effects of physical embodiment and physical presence were explored through a survey of 33 experimental works comparing how people interacted with physical robots and virtual agents. A qualitative assessment of the direction of quantitative effects demonstrated that robots were more persuasive and perceived more positively when physically present in a user׳s environment than when digitally-displayed on a screen either as a video feed of the same robot or as a virtual character analog; robots also led to better user performance when they were collocated as opposed to shown via video on a screen. However, participants did not respond differently to physical robots and virtual agents when both were displayed digitally on a screen – suggesting that physical presence, rather than physical embodiment, characterizes people׳s responses to social robots. Implications for understanding psychological response to physical and virtual agents and for methodological design are discussed. 相似文献
35.
Supported metal catalysts, particularly noble metals supported on SiO2, have attracted considerable attention due to the importance of the silica–metal interface in heterogeneous catalysis and in electronic device fabrication. Several important issues, e.g., the stability of the metal–oxide interface at working temperatures and pressures, are not well-understood. In this review, the present status of our understanding of the metal–silica interface is reviewed. Recent results of model studies in our laboratories on Pd/SiO2/Mo(1 1 2) using LEED, AES and STM are reported. In this work, epitaxial, ultrathin, well-ordered SiO2 films were grown on a Mo(1 1 2) substrate to circumvent complications that frequently arise from the silica–silicon interface present in silica thin films grown on silicon. 相似文献
36.
Discrete time queueing systems have been successfully used to model packet queues in computer and digital communications systems. In this article we introduce a novel approach to analyzing the GeoX/GeoY/∞ queueing system, which is suitable for modelling high speed computer and communications systems. The approach is based on characterizing the system by a functional equation which is then solved recursively to give identical results to those obtained using other approaches. 相似文献
37.
提出在县市级广电宽带数据网络的建设过程中,要着眼业务发展,突出高扩展性,构建基于标准、扩展灵活的主干网,实现网络建设的可持续性发展,并结合实际,从核心设备、端口、中继带宽、网络业务4个方面对扩展能力进行了阐述. 相似文献
38.
Study of elastic wave propagation induced by piezoelectric actuators for crack identification 总被引:1,自引:0,他引:1
The current paper provides a theoretical study of elastic wave propagation in a cracked elastic medium induced by an embedded piezoelectric actuator. The formulation of the problem is based on a newly developed actuator model and the solution of coupled crack and actuator problems. The interaction between an actuator and a crack is studied to develop basic understanding of the effect of the crack upon the wave field generated. The resulting wave field is used to simulate 'sensor signals'. Scattered wave from the crack is then regenerated by solving a reverse elastodynamic problem and used in an imaging technique to identify the crack. 相似文献
39.
Using an integrated process of data and modeling in HRA 总被引:1,自引:0,他引:1
John Wreathall Dennis Bley Emilie Roth Jordan Multer Thomas Raslear 《Reliability Engineering & System Safety》2004,83(2):221
The paper describes an approach taken to estimate the probabilities of failure associated with various railroad tasks to prevent accidents (principally collisions and derailments). These probabilities were estimated using an expert elicitation process that used partially relevant data available from a variety of databases and that were filtered and scaled to make them more directly relevant to the analyses being performed. Extensive qualitative studies were performed prior to the elicitation process to identify relevant contexts under which the tasks can be performed. 相似文献
40.
Yuqin LiHatsuo Ishida 《Polymer》2003,44(21):6571-6577
Polystyrene nanocomposites have been prepared via solution intercalation method. Combination of wide-angle X-ray diffraction and thermogravimetric analysis is used to study the effect of solvents on the morphology of the nanocomposites as a function of the amount of residual solvent. d-Spacing of the polystyrene nanocomposites has a minimum value when the residual solvent concentration is between 2 and 4 wt%. Different interaction level between the solvent molecules and polymer chains is considered to be the reason for this special d-spacing change behavior. By comparing the solution intercalation of polystyrene and poly(ethyl methacrylate) from different solvents, it is concluded that the interactions between polymer-surfactant, solvent-surfactant, and polymer-solvent play important role for the solution intercalation of polymers. 相似文献