全文获取类型
收费全文 | 667篇 |
免费 | 38篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 3篇 |
综合类 | 2篇 |
化学工业 | 179篇 |
金属工艺 | 13篇 |
机械仪表 | 16篇 |
建筑科学 | 20篇 |
矿业工程 | 1篇 |
能源动力 | 19篇 |
轻工业 | 23篇 |
水利工程 | 4篇 |
无线电 | 61篇 |
一般工业技术 | 133篇 |
冶金工业 | 24篇 |
原子能技术 | 6篇 |
自动化技术 | 202篇 |
出版年
2023年 | 8篇 |
2022年 | 10篇 |
2021年 | 19篇 |
2020年 | 9篇 |
2019年 | 10篇 |
2018年 | 26篇 |
2017年 | 10篇 |
2016年 | 28篇 |
2015年 | 22篇 |
2014年 | 31篇 |
2013年 | 28篇 |
2012年 | 51篇 |
2011年 | 66篇 |
2010年 | 41篇 |
2009年 | 42篇 |
2008年 | 38篇 |
2007年 | 32篇 |
2006年 | 25篇 |
2005年 | 15篇 |
2004年 | 22篇 |
2003年 | 22篇 |
2002年 | 23篇 |
2001年 | 10篇 |
2000年 | 10篇 |
1999年 | 9篇 |
1998年 | 10篇 |
1997年 | 8篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1970年 | 2篇 |
1965年 | 1篇 |
1963年 | 1篇 |
1962年 | 3篇 |
1961年 | 2篇 |
1960年 | 2篇 |
1958年 | 1篇 |
1957年 | 2篇 |
1956年 | 4篇 |
1955年 | 3篇 |
1954年 | 2篇 |
1953年 | 2篇 |
排序方式: 共有706条查询结果,搜索用时 31 毫秒
61.
Van Driessche B Tafforeau L Hentges P Carr AM Vandenhaute J 《Yeast (Chichester, England)》2005,22(13):1061-1068
The one-step PCR-mediated technique used for modification of chromosomal loci is a powerful tool for functional analysis in yeast. Both Saccharomyces cerevisiae and Schizosaccharomyces pombe are amenable to this technique. However, the scarce availability of selectable markers for Sz. pombe hampers the easy use of this technique in this species. Here, we describe the construction of new vectors deriving from the pFA6a family, which are suitable for tagging in both yeasts owing to the presence of a nourseothricin-resistance cassette. These plasmids allow various gene manipulations at chromosomal loci, viz. N- and C-terminal tagging with 3HA (haemagglutinin) or 13Myc epitopes, GST (glutathione S-transferase), 4TAP (tandem affinity purification) and several GFP (green fluorescent protein) isoforms. For N-terminal modifications, the use of different promoters allows constitutive (PADH1) or regulatable (PGAL1) promoters for S. cerevisiae and derivatives of Pnmt1 for Sz. pombe expression. 相似文献
62.
Maïwenn Kersaudy-Kerhoas Resham Dhariwal Marc P. Y. Desmulliez Lionel Jouvet 《Microfluidics and nanofluidics》2010,8(1):105-114
The separation of red blood cells from plasma flowing in microchannels is possible by biophysical effects such as the Zweifach–Fung
bifurcation law. In the present study, daughter channels are placed alongside a main channel such that cells and plasma are
collected separately. The device is aimed to be a versatile but yet very simple module producing high-speed and high-efficiency
plasma separation. The resulting lab-on-a-chip is manufactured using biocompatible materials. Purity efficiency is measured
for mussel and human blood suspensions as different parameters, such as flow rate and geometries of the parent and daughter
channels are varied. The issues of blood plasma separation at the microscale are discussed in relation to the different regimes
of flow. Results are compared with those obtained by other researchers in the field of micro-separation of blood. 相似文献
63.
Abnormal rhythms of the heart are often preceded by the occurrence of ectopic beats. These are difficult to detect as their shape is not very different from that of a normal QRS complex, the main feature in the electrocardiogram. We show how an auto-asociative multi-layer perceptron can be trained to detect normal beats only, so that the subtle abnormalities in shape of ectopic beats become clearly identifiable. This is a generic detector of abnormal beats (i.e. beats whose morphology is different from that of a normal beat) and we use ventricular ectopic beats to illustrate the performance of the algorithm. We also propose a new parameter, the variance ratio, to monitor the progress of learning in an auto-associative network. 相似文献
64.
Mohamed Assidi Lionel Fourment Simon Guerdoux Tracy Nelson 《International Journal of Machine Tools and Manufacture》2010,50(2):143-155
The accurate 3D finite element simulation of the Friction Stir Welding (FSW) process requires a proper knowledge of both material and interface behaviors, but friction, the key phenomenon of this process, is quite difficult to model and identify. According to the extreme encountered conditions and the highly coupled nature of the material flow, simple tribological tests are not representative enough, so the welding process itself has been utilized in most analyses of the literature, although its complexity has led to use simplified numerical models and approaches. The recent development of more accurate 3D simulation software, which allows modeling the entire complexity of the FSW process, makes it possible to follow a much more rigorous inverse analysis (or calibration) approach. FSW trials are conducted on an Al 6061 aluminum plate with an unthreaded concave tool. Forces and tool temperatures are accurately recorded at steady welding state, for different welding speeds. The numerical simulations are based on an Arbitrary Lagrangian Eulerian (ALE) formulation that has been implemented in the Forge3® F.E. software. The main feature of the numerical approach is to accurately compute the contact and frictional surface between the plate and the tool. A first study using Norton's friction model show the great sensitivity of welding forces and tool temperatures to friction coefficients, the need to take into account the changes brought to the contact surface by slight friction variations (thanks to the ALE formulation), the possibility to get very accurate calibrations on forces, and the impossibility to properly render the tool temperature profile. On the other hand, the use of Coulomb's friction model allows obtaining realistic temperature profiles and so calibrating a friction coefficient that offers an excellent agreement with experiments, on forces as much as on tool temperatures, for various welding speeds. 相似文献
65.
Chasen Ranger Vahid Tari Susan Farjami Matthew J. Merwin Lionel Germain Anthony Rollett 《Metallurgical and Materials Transactions A》2018,49(10):4521-4535
Texture and grain size distribution of the austenite phase at high temperature have distinct effects on the subsequent transformed microstructure and mechanical properties of steel alloys at room temperature. Measurement of austenite at high temperature is not, however, a trivial task especially if orientation maps are desired. Therefore, a technique for determining austenite texture and grain size that was present at high temperature is highly desirable. In this work, we review several pipe samples intended for use as well casing with large variations in toughness and martensitic microstructures at room temperature. Microstructural analysis of the martensite structures could not easily explain these differences due to how martensite forms from austenite. An algorithm was developed to reconstruct the parent austenite at high temperature from martensite microstructure at room temperature. This technique successfully reconstructed orientation maps for the prior austenite in these samples, demonstrating differences in texture, grain orientation spread, and austenite grain size that could account for the differences in mechanical properties. 相似文献
66.
67.
Enhancing the biofiltration of geosmin by seeding sand filter columns with a consortium of geosmin-degrading bacteria 总被引:1,自引:0,他引:1
Geosmin is a secondary metabolite that can be produced by many species of cyanobacteria and Actinomycetes. It imparts a musty/earthy taste and odour to drinking water which can result in consumer complaints and a general perception that there is a problem with the water quality. As geosmin is recalcitrant to conventional water treatment, processes are sought to ensure effective removal of this compound from potable water. Biological filtration (biofiltration) is an attractive option for geosmin removal as this compound has been shown to be biodegradable. However, effective biofiltration of geosmin can be site specific as it is highly dependent upon the types of organism present and there is often an extended acclimation period before efficient removals are achieved. We report here, a novel approach to enhance the biofiltration of geosmin by seeding sand filter columns with a bacterial consortium previously shown to be capable of effectively degrading geosmin. Geosmin removals of up to 75% were evident through sand columns which had been inoculated with the geosmin-degrading bacteria, when compared with non-inoculated sand columns where geosmin removals were as low as 25%. These low geosmin removals through the non-inoculated sand columns are consistent with previous studies and were attributed to physical/abiotic losses. The presence of an existing biofilm was shown to influence geosmin removal, as the biofilm allowed for greater attachment of the geosmin-degrading consortium (as determined by an ATP assay), and enhanced removals of geosmin. Minimal difference in geosmin removal was observed when the geosmin-degrading bacteria were inoculated into the sand columns containing either an active or inactive biofilm. 相似文献
68.
AFM Imaging of Molecular Spin‐State Changes through Quantitative Thermomechanical Measurements
下载免费PDF全文
![点击此处可从《Advanced materials (Deerfield Beach, Fla.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
69.
70.
Frank Schulze Anke Dienelt Sven Geissler Paul Zaslansky Janosch Schoon Katja Henzler Peter Guttmann Azza Gramoun Lindsey A. Crowe Lionel Maurizi Jean‐Paul Vallée Heinrich Hofmann Georg N. Duda Andrea Ode 《Small (Weinheim an der Bergstrasse, Germany)》2014,10(21):4340-4351
Mesenchymal stromal cells (MSCs) are promising candidates in regenerative cell‐therapies. However, optimizing their number and route of delivery remains a critical issue, which can be addressed by monitoring the MSCs’ bio‐distribution in vivo using super‐paramagnetic iron‐oxide nanoparticles (SPIONs). In this study, amino‐polyvinyl alcohol coated (A‐PVA) SPIONs are introduced for cell‐labeling and visualization by magnetic resonance imaging (MRI) of human MSCs. Size and surface charge of A‐PVA‐SPIONs differ depending on their solvent. Under MSC‐labeling conditions, A‐PVA‐SPIONs have a hydrodynamic diameter of 42 ± 2 nm and a negative Zeta potential of 25 ± 5 mV, which enable efficient internalization by MSCs without the need to use transfection agents. Transmission X‐ray microscopy localizes A‐PVA‐SPIONs in intracellular vesicles and as cytosolic single particles. After identifying non‐interfering cell‐assays and determining the delivered and cellular dose, in addition to the administered dose, A‐PVA‐SPIONs are found to be non‐toxic to MSCs and non‐destructive towards their multi‐lineage differentiation potential. Surprisingly, MSC migration is increased. In MRI, A‐PVA‐SPION‐labeled MSCs are successfully visualized in vitro and in vivo. In conclusion, A‐PVA‐SPIONs have no unfavorable influences on MSCs, although it becomes evident how sensitive their functional behavior is towards SPION‐labeling. And A‐PVA‐SPIONs allow MSC‐monitoring in vivo. 相似文献