全文获取类型
收费全文 | 1466篇 |
免费 | 41篇 |
专业分类
电工技术 | 34篇 |
综合类 | 4篇 |
化学工业 | 341篇 |
金属工艺 | 19篇 |
机械仪表 | 20篇 |
建筑科学 | 65篇 |
矿业工程 | 1篇 |
能源动力 | 35篇 |
轻工业 | 148篇 |
水利工程 | 3篇 |
石油天然气 | 1篇 |
无线电 | 101篇 |
一般工业技术 | 194篇 |
冶金工业 | 334篇 |
原子能技术 | 16篇 |
自动化技术 | 191篇 |
出版年
2021年 | 26篇 |
2020年 | 17篇 |
2019年 | 13篇 |
2018年 | 23篇 |
2017年 | 13篇 |
2016年 | 21篇 |
2015年 | 22篇 |
2014年 | 28篇 |
2013年 | 48篇 |
2012年 | 67篇 |
2011年 | 63篇 |
2010年 | 49篇 |
2009年 | 54篇 |
2008年 | 49篇 |
2007年 | 49篇 |
2006年 | 42篇 |
2005年 | 37篇 |
2004年 | 35篇 |
2003年 | 30篇 |
2002年 | 29篇 |
2001年 | 21篇 |
2000年 | 28篇 |
1999年 | 32篇 |
1998年 | 56篇 |
1997年 | 34篇 |
1996年 | 37篇 |
1995年 | 33篇 |
1994年 | 25篇 |
1993年 | 22篇 |
1992年 | 17篇 |
1990年 | 13篇 |
1989年 | 18篇 |
1988年 | 18篇 |
1987年 | 14篇 |
1984年 | 15篇 |
1982年 | 13篇 |
1981年 | 20篇 |
1979年 | 20篇 |
1978年 | 11篇 |
1977年 | 18篇 |
1976年 | 15篇 |
1975年 | 13篇 |
1974年 | 18篇 |
1973年 | 19篇 |
1971年 | 12篇 |
1970年 | 15篇 |
1969年 | 22篇 |
1968年 | 17篇 |
1967年 | 12篇 |
1966年 | 22篇 |
排序方式: 共有1507条查询结果,搜索用时 421 毫秒
101.
-The possibilities for describing sitting postural control using nonlinear methods was investigated during long-term driving. A total of 85 min of motorway driving intervals (n=12) were used for analysis. The results show that contrary to conventional analysis techniques, nonlinear measures were able to identify a threshold behavior describing the change in discomfort. Visual recurrence plots showed a clear change in the underlying dynamics after 1 hr of driving. The result was confirmed by the statistically significant differences in the stability and complexity of the COP time series, as explored using recurrence quantification analysis and spatio-temporal entropy. The findings of the experiment are consistent with the literature, and present a novel way to uncover transitions of discomfort stages in sitting behavioral research. 相似文献
102.
Helmut Hlavacs Roman Weidlich Karin A. Hummel Amine M. Houyou Andreas Berl Hermann de Meer 《电信纪事》2008,63(9-10):473-485
In this paper, a new architecture for sharing resources among home environments is proposed. Our approach goes far beyond traditional systems for distributed virtualization, like PlanetLab or grid computing, as it relies on complete decentralization in a peer-to-peer (P2P) like manner and, above all, aims at energy efficiency. Energy metrics are defined, which have to be optimized by the system. The system itself uses virtualization to transparently move tasks from one home to another to optimally utilize the existing computing power. We present an overview of our proposed architecture, consisting of a middleware interconnecting computers and routers in possibly millions of homes using P2P techniques. For demonstrating the potential energy saving of distributed applications, we present an analytical model for sharing downloads, which is verified by discrete event simulation. The model represents an optimistic case without P2P overhead and fairness. The model allows to assess the upper limit of the saving potential. An enhanced version of the simulation model also shows the effect of fairness. The fairer the system gets, the less efficient it is. 相似文献
103.
104.
Hermann Kaiser 《工业材料与腐蚀》1989,40(1):1-6
Investigation of phase transformations induced by the selective dissolution of In from InSn alloys . In the context with the theory of dealloying the selective dissolution of In from InSn alloys has been investigated. As a consequence of their low melting-point the corrosion behaviour of these alloys differs significantly from the behaviour of higher-melting alloys. For the β-InSn phase this is illustrated by the result that a Sn-content of 20 at.%, supported by a porous morphology of the γ-SnIn product phase, does not excert a significant influence on the In-dissolution kinetics. Selective dissolution of In from γ-SnIn and from the β-Sn terminal phase is controlled, however, by solid-state diffusion of In to the electrode surface. Under these circumstances the product phase β-Sn that results from the removal of In from γ-SnIn at room temperature grows with a morphological stable interface and the concentration profiles within the interdiffusion zones can be directly detected by electron microprobe analysis. 相似文献
105.
Synthesis of 2‐[18F]Fluoro‐2‐deoxyisosorbide 5‐mononitrate and Assessment of Its in vivo Biodistribution as Determined by Dynamic Positron Emission Tomography (PET)
下载免费PDF全文
![点击此处可从《ChemMedChem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Nico Santschi Dr. Stefan Wagner Dr. Constantin Daniliuc Dr. Sven Hermann Prof. Dr. Michael Schäfers Prof. Dr. Ryan Gilmour 《ChemMedChem》2015,10(10):1724-1732
Herein we disclose the synthesis of 2‐fluoro‐2‐deoxyisosorbide 5‐mononitrate (2F‐IS‐5MN), a fluorinated analogue of the commonly prescribed vasodilator isosorbide 5‐mononitrate (IS‐5MN). X‐ray structural data for IS‐5MN and its C2‐epimeric congener IM‐5MN are presented together with structural data for 2F‐IS‐5MN. Radioisotope labeling of 2F‐IS‐5MN has, for the first time, allowed observation of the in vivo biodistribution of this organic nitrate by means of dynamic positron emission tomography (PET) in wild‐type mice. 相似文献
106.
Lars Egmont Spelter Anna Steiwand Hermann Nirschl 《Chemical engineering science》2010,65(14):4173-4181
The demand for instruments that are suitable for the separation of fine particles and biological cells is steadily increasing. Various innovative particles have already implemented in bulk products and many others are close to commercial availability. Tubular bowl centrifuges offer high centrifugal forces at reasonable throughputs. There is a high potential for the optimisation of existing processes and in the design of new tubular centrifuges especially for the separation of nanoscale materials. The separation of fine particulates and biological cells in a semibatch tubular bowl centrifuge at high rotational speeds is described in this work. Furthermore, the influence of the sediment on the process outcome and possibilities to enhance the separation efficiency were investigated. A boundary layer flow was indirectly detected. Structures inside the rotor of the centrifuge cause defined liquid flow patterns, which influence the separation efficiency. A comparison of the separation behaviour with an unimpaired flow and the redirected flow yielded conclusions about the actual flow patterns. 相似文献
107.
Constable EC Housecroft CE Mayor M Meier WP Palivan CG Wegner HA Wennemers H 《Chimia》2010,64(12):877-884
The following contributions describe various research activities of the Department of Chemistry, University of Basel in the area of nanochemistry and supramolecular chemistry. 相似文献
108.
109.
Hans‐Jörg Breyholz Dr. Stefan Wagner Dr. Andreas Faust Dr. Burkhard Riemann Prof. Dr. Carsten Höltke Dr. Sven Hermann Dr. Otmar Schober Prof. Dr. Michael Schäfers Prof. Dr. Klaus Kopka Priv.‐Doz. Dr. 《ChemMedChem》2010,5(5):777-789
Matrix metalloproteinases (MMPs) are zinc‐ and calcium‐dependent endopeptidases. Representing a subfamily of the metzincin superfamily, MMPs are involved in the proteolytic degradation of components of the extracellular matrix. Unregulated MMP expression, MMP dysregulation and locally increased MMP activity are common features of various diseases, such as cancer, atherosclerosis, stroke, arthritis, and others. Therefore, activated MMPs are suitable biological targets for the specific visualization of such pathologies, in particular by using radiolabeled MMP inhibitors (MMPIs). The aim of this work was to develop a radiofluorinated molecular probe for noninvasive in vivo imaging for the detection of up‐regulated levels of activated MMPs in the living organism. Fluorinated MMPIs ( 26 , 31 and 38 ) based on the pyrimidine‐2,4,6‐trione lead structure RO 28‐2653 ( 1 ) were synthesized, and their MMP inhibition potency was evaluated in vitro. The radiosynthesis and the in vivo biodistribution of the first 18F‐labeled prototype, MMP‐targeted tracer [18F] 26 , suitable for molecular imaging by means of positron emission tomography (PET) were realized. 相似文献
110.
Rudolf?MoosbeckhoferEmail author Hermann?Pechhacker Heidrun?Unterweger Franz?Bandion Andreas?Heinrich-Lenz 《European Food Research and Technology》2003,217(1):49-52
Varroa destructor, an ectoparasitic mite, is one of the major pests of honeybees in many parts of the world. In order to keep bee colonies alive and productive, effective biological, biotechnical, or acaricidal control measures are necessary. Oxalic acid is one substance under discussion to replace synthetic acaricides (e.g. pyrethroids, organophosphates) to minimize the risk of residues in bee products. The application of oxalic acid based solutions (Bienenwohl or a self-prepared oxalic acid solution with sugar) to control Varroa destructor resulted in no relevant changes in the oxalic acid content of honey produced the following year, compared with honey samples from untreated colonies from the same location. The range of oxalic acid content in honey was 5–68 mg/kg in oxalic acid treated and 5–65 mg/kg in untreated colonies. The oxalic acid content of the honey was positively correlated with its electrical conductivity and thus with its original nectar or honeydew source. 相似文献