全文获取类型
收费全文 | 3786篇 |
免费 | 221篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 68篇 |
综合类 | 15篇 |
化学工业 | 815篇 |
金属工艺 | 83篇 |
机械仪表 | 74篇 |
建筑科学 | 210篇 |
矿业工程 | 4篇 |
能源动力 | 95篇 |
轻工业 | 381篇 |
水利工程 | 33篇 |
石油天然气 | 23篇 |
无线电 | 293篇 |
一般工业技术 | 629篇 |
冶金工业 | 582篇 |
原子能技术 | 33篇 |
自动化技术 | 670篇 |
出版年
2023年 | 55篇 |
2022年 | 86篇 |
2021年 | 126篇 |
2020年 | 65篇 |
2019年 | 68篇 |
2018年 | 83篇 |
2017年 | 87篇 |
2016年 | 126篇 |
2015年 | 123篇 |
2014年 | 140篇 |
2013年 | 212篇 |
2012年 | 182篇 |
2011年 | 244篇 |
2010年 | 216篇 |
2009年 | 156篇 |
2008年 | 176篇 |
2007年 | 147篇 |
2006年 | 153篇 |
2005年 | 130篇 |
2004年 | 98篇 |
2003年 | 93篇 |
2002年 | 87篇 |
2001年 | 76篇 |
2000年 | 52篇 |
1999年 | 71篇 |
1998年 | 158篇 |
1997年 | 97篇 |
1996年 | 71篇 |
1995年 | 57篇 |
1994年 | 41篇 |
1993年 | 50篇 |
1992年 | 26篇 |
1991年 | 18篇 |
1990年 | 25篇 |
1989年 | 31篇 |
1988年 | 24篇 |
1987年 | 23篇 |
1986年 | 18篇 |
1985年 | 31篇 |
1984年 | 15篇 |
1983年 | 20篇 |
1982年 | 16篇 |
1981年 | 16篇 |
1980年 | 16篇 |
1979年 | 15篇 |
1978年 | 10篇 |
1977年 | 11篇 |
1976年 | 37篇 |
1970年 | 8篇 |
1969年 | 11篇 |
排序方式: 共有4008条查询结果,搜索用时 15 毫秒
121.
122.
Porous Materials: Direct Laser Writing of Low‐Density Interdigitated Foams for Plasma Drive Shaping (Adv. Funct. Mater. 43/2017)
下载免费PDF全文
![点击此处可从《Advanced functional materials》网站下载免费的PDF全文](/ch/ext_images/free.gif)
James S. Oakdale Raymond F. Smith Jean‐Baptiste Forien William L. Smith Suzanne J. Ali Leonardus B. Bayu Aji Trevor M. Willey Jianchao Ye Anthony W. van Buuren Matthew A. Worthington Shon T. Prisbrey Hye‐Sook Park Peter A. Amendt Theodore F. Baumann Juergen Biener 《Advanced functional materials》2017,27(43)
123.
Hydrogenation of p‐Nitrophenol to p‐Aminophenol as a Test Reaction for the Catalytic Activity of Supported Pt Catalysts
下载免费PDF全文
![点击此处可从《化学工程与技术》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Michael Goepel Majd Al‐Naji Patrick With Gerald Wagner Oliver Oeckler Dirk Enke Roger Gläser 《化学工程与技术》2014,37(3):551-554
Hydrogenation of p‐nitrophenol (PNP) to p‐aminophenol (PAP) using NaBH4 as a reducing agent was studied as a test reaction for determining the catalytic activity of supported Pt catalysts. The initial reaction rate, which is accessible within less than 10 min via online UV‐vis spectroscopy at room temperature, ambient pressure, and in water as solvent, was applied as measure for catalytic activity. For three Pt catalysts supported on porous SiO2, porous glass, and Al2O3, respectively, significant differences in the catalytic activity by almost one order of magnitude were observed. However, especially in the case of very active catalysts, limitations of the reaction by internal or external mass transfer have to be considered. 相似文献
124.
Li‐Hua Shao Juergen Biener Hai‐Jun Jin Monika M. Biener Theodore F. Baumann Jörg Weissmüller 《Advanced functional materials》2012,22(14):3029-3034
A novel nanoporous carbon/electrolyte hybrid material is reported for use in actuation. The nanoporous carbon matrix provides a 3D network that combines mechanical strength, light weight, and low cost with an extremely high surface area. In contrast to lower dimensional nanomaterials, the nanoporous carbon matrix can be prepared in the form of macroscopic monolithic samples that can be loaded in compression. The hybrid material is formed by infiltrating the free internal pore volume of the carbon with an electrolyte. Actuation is prompted by polarizing the internal interfaces via an applied electric bias. It is found that the strain amplitude is proportional to the Brunauer‐Emmett‐Teller (BET) mass specific surface area, with reversible volume strain amplitudes up to the exceptionally high value of 6.6%. The mass‐specific strain energy density compares favorably to reported values for piezoceramics and for nanoporous metal actuators. 相似文献
125.
Front Cover: Photoactivatable Mussel‐Based Underwater Adhesive Proteins by an Expanded Genetic Code (ChemBioChem 18/2017)
下载免费PDF全文
![点击此处可从《Chembiochem : a European journal of chemical biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Matthias Hauf Dr. Florian Richter Tobias Schneider Thomas Faidt Dr. Berta M. Martins Dr. Tobias Baumann Dr. Patrick Durkin Prof. Dr. Holger Dobbek Prof. Dr. Karin Jacobs Prof. Dr. Andreas Möglich Prof. Dr. Nediljko Budisa 《Chembiochem : a European journal of chemical biology》2017,18(18):1771-1771
126.
A two-dimensional line source outflow is considered, in which the evolution of a sharp interface separating an incompressible fluid from a bounding weakly compressible gas is analysed. Linear theory is applied, assuming that anisotropies in the source outflow are small, to develop an approximate solution for the interfacial evolution. The simplest solutions to the governing linearised equations require the presence of a high-order velocity singularity at the location of the line source. A spectral method is also developed to capture the nonlinear behaviour of the flow; after some finite time, curvature singularities are found to develop on the interface. Comparisons are made between the stability of the interface and its analogue which separates two incompressible fluids. It is found that when the bounding fluid is weakly compressible rather than incompressible, the stability of the interface is significantly increased. 相似文献
127.
Xavier Lladó Arnau Oliver Mariano Cabezas Jordi Freixenet Joan C. Vilanova Ana Quiles Laia Valls Lluís Ramió-Torrentà Àlex Rovira 《Information Sciences》2012,186(1):164-185
Automatic segmentation of multiple sclerosis (MS) lesions in brain MRI has been widely investigated in recent years with the goal of helping MS diagnosis and patient follow-up. However, the performance of most of the algorithms still falls far below expert expectations. In this paper, we review the main approaches to automated MS lesion segmentation. The main features of the segmentation algorithms are analysed and the most recent important techniques are classified into different strategies according to their main principle, pointing out their strengths and weaknesses and suggesting new research directions. A qualitative and quantitative comparison of the results of the approaches analysed is also presented. Finally, possible future approaches to MS lesion segmentation are discussed. 相似文献
128.
Chun Chen William T. Baumann Jianhua Xing Lingling Xu Robert Clarke John J. Tyson 《Journal of the Royal Society Interface》2014,11(96)
Endocrine therapy, targeting the oestrogen receptor pathway, is the most common treatment for oestrogen receptor-positive breast cancers. Unfortunately, these tumours frequently develop resistance to endocrine therapies. Among the strategies to treat resistant tumours are sequential treatment (in which second-line drugs are used to gain additional responses) and intermittent treatment (in which a ‘drug holiday’ is imposed between treatments). To gain a more rigorous understanding of the mechanisms underlying these strategies, we present a mathematical model that captures the transitions among three different, experimentally observed, oestrogen-sensitivity phenotypes in breast cancer (sensitive, hypersensitive and independent). To provide a global view of the transitions between these phenotypes, we compute the potential landscape associated with the model. We show how this oestrogen response landscape can be reshaped by population selection, which is a crucial force in promoting acquired resistance. Techniques from statistical physics are used to create a population-level state-transition model from the cellular-level model. We then illustrate how this population-level model can be used to analyse and optimize sequential and intermittent oestrogen-deprivation protocols for breast cancer. The approach used in this study is general and can also be applied to investigate treatment strategies for other types of cancer. 相似文献
129.
The routines of information work are commonplace yet difficult to characterize. Although cognitive models have successfully characterized routine tasks within which there is little variation, a large body of ethnomethodological research has identified the inherent nonroutineness of routines in information work. We argue that work does not fall into discrete classes of routine versus nonroutine; rather, task performance lies on a continuum of routineness, and routineness metrics are important to the understanding of workplace multitasking. In a study of 10 information workers shadowed for 3 whole working days each, we utilize the construct of working sphere to model projects/tasks as a network of humans and artifacts. Employing a statistical technique called T-pattern analysis, we derive measures of routineness from these real-world data. In terms of routineness, we show that information workers experience archetypes of working spheres. The results indicate that T-patterns of interactions with information and computational media are important indicators of facets of routineness and that these measures are correlated with workers' affective states. Our results are some of the first to demonstrate how regular temporal patterns of media interaction in tasks are related to stress. These results suggest that designs of systems to facilitate so-called routine work should consider the degrees to which a person's working spheres fall along varying facets of routineness. 相似文献
130.
Maize is an important foodstuff in many countries, and one of most susceptible crops to mold and aflatoxin contamination, which results in considerable postharvest losses and is a burden to consumers’ health, especially in developing countries. The timely drying of harvested maize is essential to halt mold development, ensuring safe storage. The effect of the incorporation of a superabsorbent polymer (SAP) as desiccant in a maize dryer was studied using computational fluid dynamics simulations which accounted for heat and mass transfer between maize, SAP and air. The adsorption capacity and adsorption rate of a commercial SAP material were experimentally determined at different temperature and relative humidity levels, which served as basis for the adsorption model required in the simulations. A maize bulk with SAP packages distributed in it was modeled. Results showed that the SAP material increases the drying rate substantially, particularly in the upper bulk zone where the air reaching it is dehumidified the most. The maize closer to the upper bulk surface starts drying from the beginning of the process instead of lagging for hours or days before the drying front reaches it. An inconvenience of the SAP material is the tendency of granules to swell and stick together as moisture reaches a threshold, which may reduce its performance. Thus, provided this issue is resolved or minimized, SAP materials could successfully assist the rapid drying of maize and other crops. They may also be used during storage to avoid rewetting of the crops during periods of high relative humidity. 相似文献