全文获取类型
收费全文 | 2025篇 |
免费 | 75篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 36篇 |
综合类 | 6篇 |
化学工业 | 626篇 |
金属工艺 | 54篇 |
机械仪表 | 44篇 |
建筑科学 | 125篇 |
矿业工程 | 9篇 |
能源动力 | 46篇 |
轻工业 | 132篇 |
水利工程 | 5篇 |
无线电 | 132篇 |
一般工业技术 | 362篇 |
冶金工业 | 114篇 |
原子能技术 | 28篇 |
自动化技术 | 386篇 |
出版年
2023年 | 20篇 |
2022年 | 35篇 |
2021年 | 66篇 |
2020年 | 34篇 |
2019年 | 35篇 |
2018年 | 37篇 |
2017年 | 38篇 |
2016年 | 72篇 |
2015年 | 53篇 |
2014年 | 63篇 |
2013年 | 93篇 |
2012年 | 112篇 |
2011年 | 144篇 |
2010年 | 113篇 |
2009年 | 95篇 |
2008年 | 111篇 |
2007年 | 94篇 |
2006年 | 109篇 |
2005年 | 75篇 |
2004年 | 76篇 |
2003年 | 49篇 |
2002年 | 42篇 |
2001年 | 40篇 |
2000年 | 33篇 |
1999年 | 37篇 |
1998年 | 38篇 |
1997年 | 33篇 |
1996年 | 24篇 |
1995年 | 22篇 |
1994年 | 24篇 |
1993年 | 20篇 |
1992年 | 22篇 |
1991年 | 21篇 |
1990年 | 16篇 |
1989年 | 15篇 |
1988年 | 10篇 |
1987年 | 14篇 |
1985年 | 13篇 |
1984年 | 9篇 |
1983年 | 11篇 |
1982年 | 12篇 |
1981年 | 11篇 |
1980年 | 13篇 |
1979年 | 11篇 |
1978年 | 9篇 |
1977年 | 10篇 |
1976年 | 8篇 |
1975年 | 14篇 |
1974年 | 16篇 |
1973年 | 7篇 |
排序方式: 共有2105条查询结果,搜索用时 15 毫秒
101.
The phase formation of carbides and borides during high-energy ball milling has been investigated by measuring the gas temperature inside the vial and by X-ray diffraction studies of specimens taken at different stages of the milling process. The formation mechanism changes from a gradual process to an instantaneous, explosion-like reaction with increasing milling intensity and enthalpy of product formation. Finally, a model was developed to describe the milling process, and to determine the peak temperatures that are reached in the powder particles during ball collisions as well as the microstructure evolution. Using an effective coefficient of diffusion and calculating the evolution of the continuously growing diffusion layer, it was possible to determine whether and when rapid phase formation occurs. The model was tested by reproducing the milling times needed for rapid phase formation inside the mill. 相似文献
102.
103.
104.
Max Braune Nico Scherf Claudia Heine Katja Sygnecka Thanigaimalai Pillaiyar Chiara Parravicini Bernd Heimrich Maria P. Abbracchio Christa E. Müller Heike Franke 《International journal of molecular sciences》2021,22(21)
Characterization of new pharmacological targets is a promising approach in research of neurorepair mechanisms. The G protein-coupled receptor 17 (GPR17) has recently been proposed as an interesting pharmacological target, e.g., in neuroregenerative processes. Using the well-established ex vivo model of organotypic slice co-cultures of the mesocortical dopaminergic system (prefrontal cortex (PFC) and substantia nigra/ventral tegmental area (SN/VTA) complex), the influence of GPR17 ligands on neurite outgrowth from SN/VTA to the PFC was investigated. The growth-promoting effects of Montelukast (MTK; GPR17- and cysteinyl-leukotriene receptor antagonist), the glial cell line-derived neurotrophic factor (GDNF) and of two potent, selective GPR17 agonists (PSB-16484 and PSB-16282) were characterized. Treatment with MTK resulted in a significant increase in mean neurite density, comparable with the effects of GDNF. The combination of MTK and GPR17 agonist PSB-16484 significantly inhibited neuronal growth. qPCR studies revealed an MTK-induced elevated mRNA-expression of genes relevant for neuronal growth. Immunofluorescence labelling showed a marked expression of GPR17 on NG2-positive glia. Western blot and RT-qPCR analysis of untreated cultures suggest a time-dependent, injury-induced stimulation of GPR17. In conclusion, MTK was identified as a stimulator of neurite fibre outgrowth, mediating its effects through GPR17, highlighting GPR17 as an interesting therapeutic target in neuronal regeneration. 相似文献
105.
A wide range of parameters was investigated by numerical calculations concerning their impact on DC stray current corrosion of reinforced concrete (RC) structures. A simplified model geometry was used to extract the relevant parameters and their interaction in terms of stray current-affected structures. This study mainly focuses on RC structures that are fitted with cathodic protection installations. The findings reveal a complex interaction between the investigated parameters. The possible relevance of further parameters, which is not the subject of this study, was emphasised. 相似文献
106.
Possible Approaches to the Prediction of Residence Time Distributions Although the experimental determination of residence time distributions is based on a black-box method, the signal shape also permits certain conclusions to be drawn about the internal conditions. However, if it is to provide a sole basis for elucidating process steps in a plant this method is soon overtaxed. A deeper theoretical penetration of the pertinent transport processes opens up the way ahead. However, since residence time distributions are based on mass-oriented considerations, substantial advances in fluid mechanics, where location-based considerations predominate, have not led to improved predictive capability. Yet the computer power now available offers a variety of ways of calculating residence-time distributions for a known flow profile, thus permitting a step in the direction of better predictability of residence time distributions. This article presents utilisable methods and evaluates them with regard to their demands on time and effort and their predictive power. Problems arising in connection with the models are discussed. 相似文献
107.
108.
109.
Wolter Marc Tedjo-Palczynski Irene Hentschel Bernd Kuhlen Torsten 《Computer Graphics and Applications, IEEE》2009,29(6):54-64
Scientific-visualization tools can make time-varying simulations easier to understand. The growing efficiency of today's high-performance computers enables simulation of physical phenomena with a high temporal resolution. Consequently, visualization systems require efficient navigation in the temporal dimension. This 3D user interface employs direct-manipulation metaphors for temporal navigation in scientific visualizations. By interacting with objects using their 3D trajectory, users can navigate in time by specifying spatial inputs. This article is part of a special issue on 3D user interfaces. 相似文献
110.
Rainer Dudek Ralf Doering Christine Bombach Bernd Michel 《Microelectronics Reliability》2009,49(8):839-845
Secondary effects on thermal fatigue of solder joints, which frequently have been neglected, were studied by means of the finite element method (FEM). Based on a semi-empirical approach to predict fatigue life by evaluating the cyclic accumulated equivalent creep strain or energy density, effects of organic boards intrinsic properties on solder joint fatigue were investigated. Aspects of more realistic FR-4 board modelling were studied, in particular concerning its in-plane anisotropy and intrinsic warpage behaviour. Intrinsic board warpage was measured on test board level as well as for boards from series production. High intrinsic warpage was in particular found for several test boards. The effects for the worst case scenario observed so far were analysed for both first level and second level interconnects. The change in predicted fatigue life varied between 30% and 500%, the latter most critical effects were found at large QFN components. Another secondary effect studied was to include the frequently neglected interfacial intermetallics into FEM. It turned out that for components with relatively large standoff like LFBGAs the effects were actually negligible, but for the highly miniaturized components like chip resistors CR0201 they are the decisive factor. 相似文献