全文获取类型
收费全文 | 245篇 |
免费 | 28篇 |
专业分类
电工技术 | 3篇 |
综合类 | 1篇 |
化学工业 | 74篇 |
金属工艺 | 11篇 |
机械仪表 | 3篇 |
建筑科学 | 16篇 |
能源动力 | 8篇 |
轻工业 | 8篇 |
水利工程 | 1篇 |
无线电 | 23篇 |
一般工业技术 | 63篇 |
冶金工业 | 7篇 |
自动化技术 | 55篇 |
出版年
2023年 | 9篇 |
2022年 | 6篇 |
2021年 | 22篇 |
2020年 | 13篇 |
2019年 | 13篇 |
2018年 | 13篇 |
2017年 | 14篇 |
2016年 | 10篇 |
2015年 | 7篇 |
2014年 | 25篇 |
2013年 | 30篇 |
2012年 | 19篇 |
2011年 | 26篇 |
2010年 | 12篇 |
2009年 | 7篇 |
2008年 | 17篇 |
2007年 | 12篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2002年 | 2篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1997年 | 1篇 |
1993年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有273条查询结果,搜索用时 0 毫秒
41.
Florian H. Gojny Malte H.G. Wichmann Bodo Fiedler Karl Schulte 《Composites Science and Technology》2005,65(15-16):2300
Carbon nanotubes (CNTs) in general are considered to be highly potential fillers to improve the material properties of polymers. However, questions concerning the appropriate type of CNTs, e.g., single-wall CNTs (SWCNT), double-wall CNTs (DWCNT) or multi-wall CNTs (MWCNT), and the relevance of a surface functionalisation are still to be answered. This first part of the study focuses on the evaluation of the different types of nanofillers applied, their influence on the mechanical properties of epoxy-based nanocomposites and the relevance of surface functionalisation. The nanocomposites produced exhibited an enhanced strength and stiffness and even more important, a significant increase in fracture toughness (43% at 0.5 wt% amino-functionalised DWCNT). The influence of filler content, the varying dispersibility, the aspect ratio, the specific surface area and an amino-functionalisation on the composite properties are discussed and correlated to the identified micro-mechanical mechanisms. 相似文献
42.
Fouard C Malandain G Prohaska S Westerhoff M 《IEEE transactions on medical imaging》2006,25(10):1319-1328
The study of cerebral microvascular networks requires high-resolution images. However, to obtain statistically relevant results, a large area of the brain (several square millimeters) must be analyzed. This leads us to consider huge images, too large to be loaded and processed at once in the memory of a standard computer. To consider a large area, a compact representation of the vessels is required. The medial axis is the preferred tool for this application. To extract it, a dedicated skeletonization algorithm is proposed. Numerous approaches already exist which focus on computational efficiency. However, they all implicitly assume that the image can be completely processed in the computer memory, which is not realistic with the large images considered here. We present in this paper a skeletonization algorithm that processes data locally (in subimages) while preserving global properties (i.e., homotopy). We then show some results obtained on a mosaic of three-dimensional images acquired by confocal microscopy. 相似文献
43.
Polyhydroxyalkanoates (PHAs) are microbial biopolymers (polyesters) that have a wide range of functions and applications. They serve in nature mainly as carbon and energy storage materials for a variety of microorganisms. In past decades, their utilization has attracted much attention, from commodities and degradable plastics to specialty performance materials in medicine. PHA biosynthesis has been well understood, and it is now possible to design bacterial strands to produce PHAs with desired properties. The substrates for the fermentative production of PHAs are very manifold: some are derived from food‐based carbon sources (e.g., fats and oils (triglycerids)), thus raising concerns with regard to the sustainability of their productions in terms of crop area and food. In addition, hemicellulose hydrolysates, crude glycerol, and methanol are very promising carbon sources for the sustainable production of PHAs. The integration of PHA production within a modern biorefinery is an important issue and can result in a simultaneous production of biofuels and bioplastics. Furthermore, many chemical‐synthetic procedures by means of efficient catalysts can give access to a variety of PHAs. This article summarizes recent developments in these fields and emphasizes the importance of a sustainable PHA‐based industry. Practical Applications: Practical applications of the microbial polyesters PHAs are, for example, a variety of sustainably produced commodities as well as special applications in (bio)medicine, for example, tissue engineering. 相似文献
44.
Gastl Mareike Peereboom Sophie M. Fuetterer Maximilian Boenner Florian Kelm Malte Manka Robert Kozerke Sebastian 《Magma (New York, N.Y.)》2019,32(2):259-268
Magnetic Resonance Materials in Physics, Biology and Medicine - To study inter-individual differences of the relation between diaphragm and heart motion, the objective of the present study was to... 相似文献
45.
Herzen J Donath T Beckmann F Ogurreck M David C Mohr J Pfeiffer F Schreyer A 《The Review of scientific instruments》2011,82(11):113711
X-ray phase-contrast radiography and tomography enable to increase contrast for weakly absorbing materials. Recently, x-ray grating interferometers were developed that extend the possibility of phase-contrast imaging from highly brilliant radiation sources like third-generation synchrotron sources to non-coherent conventional x-ray tube sources. Here, we present the first installation of a three grating x-ray interferometer at a low-coherence wiggler source at the beamline W2 (HARWI II) operated by the Helmholtz-Zentrum Geesthacht at the second-generation synchrotron storage ring DORIS (DESY, Hamburg, Germany). Using this type of the wiggler insertion device with a millimeter-sized source allows monochromatic phase-contrast imaging of centimeter sized objects with high photon flux. Thus, biological and materials-science imaging applications can highly profit from this imaging modality. The specially designed grating interferometer currently works in the photon energy range from 22 to 30 keV, and the range will be increased by using adapted x-ray optical gratings. Our results of an energy-dependent visibility measurement in comparison to corresponding simulations demonstrate the performance of the new setup. 相似文献
46.
Andr Hofmann Malte Wallmeier Marek Hauptmann Jens‐Peter Majschak 《Packaging Technology and Science》2019,32(6):287-296
In this paper, deep‐drawn paperboard cups are characterized in terms of their elongation along the cup wall. For this purpose, a method for the non‐destructive determination of the elongation was developed and tested. Using the presented method, a parameter study of the process parameters blank holder force, forming temperature, material moisture content, drawing velocity, and clearance ratio was performed. The influence of the process parameters on the cup wall elongation was determined by statistical design of experiments. Using the determined relationships between the process parameters, it was possible to achieve a shape‐specific characterization of the elongation along the cup wall. The parameter study showed a significant influence of the blank holder force, the forming temperature, and the material moisture content to the elongation along the cup wall. 相似文献
47.
Caroline Murawski Andreas Mischok Jonathan Booth Jothi Dinesh Kumar Emily Archer Laura Tropf Chang‐Min Keum Ya‐Li Deng Kou Yoshida Ifor D. W. Samuel Marcel Schubert Stefan R. Pulver Malte C. Gather 《Advanced materials (Deerfield Beach, Fla.)》2019,31(42)
Fluorescence imaging is an indispensable tool in biology, with applications ranging from single‐cell to whole‐animal studies and with live mapping of neuronal activity currently receiving particular attention. To enable fluorescence imaging at cellular scale in freely moving animals, miniaturized microscopes and lensless imagers are developed that can be implanted in a minimally invasive fashion; but the rigidity, size, and potential toxicity of the involved light sources remain a challenge. Here, narrowband organic light‐emitting diodes (OLEDs) are developed and used for fluorescence imaging of live cells and for mapping of neuronal activity in Drosophila melanogaster via genetically encoded Ca2+ indicators. In order to avoid spectral overlap with fluorescence from the sample, distributed Bragg reflectors are integrated onto the OLEDs to block their long‐wavelength emission tail, which enables an image contrast comparable to conventional, much bulkier mercury light sources. As OLEDs can be fabricated on mechanically flexible substrates and structured into arrays of cell‐sized pixels, this work opens a new pathway for the development of implantable light sources that enable functional imaging and sensing in freely moving animals. 相似文献
48.
Microbial community structure in activated sludge floc analysed by fluorescence in situ hybridization and its relation to floc stability 总被引:4,自引:0,他引:4
The efficiency of activated sludge treatment plants is dependent on the solid-liquid separation properties of the activated sludge. A critical parameter is the stability of the microbial flocs. Weak flocs deflocculate easily leaving increased concentrations of suspended solids in the effluent. The knowledge about how different bacteria are attached to the flocs and their influence on the bioflocculation is limited. In this study, the deflocculation of different phylogenetic groups of bacteria in activated sludge from a full scale plant was investigated. The experiments were carried out by using a shear method where the sludge flocs are deflocculated under controlled shear conditions. The degree of deflocculation was measured as increase in turbidity of the supernatant. Identification and quantification of the microbial community structure of both total activated sludge and deflocculated bacteria were conducted with group-specific gene probes for broad groups of bacteria (Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria and Actinobacteria) and fluorescence in situ hybridization (FISH). The microbial community structure of the deflocculated bacteria was different compared to the total activated sludge with a higher abundance of Gammaproteobacteria in the supernatant indicating that different groups of bacteria are bound with different strength to the floc surface. The results show that the bacteria in the outer parts of the flocs are relatively loosely bound to the floc matrix and can be easily eroded from the surface when exposed to shear. 相似文献
49.
50.
Philipp B Hoff M Germa F Schink B Beimborn D Mersch-Sundermann V 《Environmental science & technology》2007,41(4):1390-1398
Prediction of the biodegradability of organic compounds is an ecologically desirable and economically feasible tool for estimating the environmental fate of chemicals. We combined quantitative structure-activity relationships (QSAR) with the systematic collection of biochemical knowledge to establish rules for the prediction of aerobic biodegradation of N-heterocycles. Validated biodegradation data of 194 N-heterocyclic compounds were analyzed using the MULTICASE-method which delivered two QSAR models based on 17 activating (OSAR 1) and on 16 inactivating molecular fragments (GSAR 2), which were statistically significantly linked to efficient or poor biodegradability, respectively. The percentages of correct classifications were over 99% for both models, and cross-validation resulted in 67.9% (GSAR 1) and 70.4% (OSAR 2) correct predictions. Biochemical interpretation of the activating and inactivating characteristics of the molecular fragments delivered plausible mechanistic interpretations and enabled us to establish the following biodegradation rules: (1) Target sites for amidohydrolases and for cytochrome P450 monooxygenases enhance biodegradation of nonaromatic N-heterocycles. (2) Target sites for molybdenum hydroxylases enhance biodegradation of aromatic N-heterocycles. (3) Target sites for hydratation by an urocanase-like mechanism enhance biodegradation of imidazoles. Our complementary approach represents a feasible strategy for generating concrete rules for the prediction of biodegradability of organic compounds. 相似文献