全文获取类型
收费全文 | 405篇 |
免费 | 27篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 90篇 |
金属工艺 | 4篇 |
机械仪表 | 7篇 |
建筑科学 | 17篇 |
能源动力 | 16篇 |
轻工业 | 34篇 |
无线电 | 43篇 |
一般工业技术 | 99篇 |
冶金工业 | 36篇 |
原子能技术 | 1篇 |
自动化技术 | 83篇 |
出版年
2024年 | 1篇 |
2023年 | 6篇 |
2022年 | 15篇 |
2021年 | 15篇 |
2020年 | 7篇 |
2019年 | 10篇 |
2018年 | 17篇 |
2017年 | 18篇 |
2016年 | 29篇 |
2015年 | 9篇 |
2014年 | 16篇 |
2013年 | 26篇 |
2012年 | 46篇 |
2011年 | 42篇 |
2010年 | 24篇 |
2009年 | 23篇 |
2008年 | 18篇 |
2007年 | 18篇 |
2006年 | 12篇 |
2005年 | 11篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 7篇 |
1995年 | 9篇 |
1994年 | 5篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有432条查询结果,搜索用时 31 毫秒
321.
Mariette Moevus Yves Jorand Christian Olagnon Sandrine Maximilien Romain Anger Laetitia Fontaine Laurent Arnaud 《Materials and Structures》2016,49(4):1555-1568
Although of interest for its low embodied energy content for construction, earth is usually not used for modern construction due to the expensive, artisanal and complicated process and the high variability of the raw material. The transfer of techniques dedicated to cement concrete could help the industrialization of this material. The use of dispersant for an improved dispersion of the earth powder has been investigated for both dispersion of earth fine fraction and water (here named the binding phase) and mortar made with calibrated sand. An improvement of the rheology is observed with lower viscosity and yield stress. This leads to a very small improvement of the density however concomitant with a marked increase of the mechanical properties, Young modulus and compressive strength. The analysis of the microstructure of the mortar shows an increase of the largest pores, and a decrease of the clay platelets flocs. The evolutions of these properties are analyzed in terms of the Rumpf model at two different scales. The dispersant mainly acts on the platelet arrangement that defines the forces between particles, but also simultaneously decreases the permeability of this binding phase, therefore entrapping more air during the mixing of the powder and water. Clearly the use of a dispersant may be of interest for the processing of earth material on liquid state, decreasing the viscosity and/or allowing the reduction of the water content, and finally improving strength. 相似文献
322.
Binary Superlattices from {Mo132} Polyoxometalates and Maghemite Nanocrystals: Long‐Range Ordering and Fine‐Tuning of Dipole Interactions
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Romain Breitwieser Thomas Auvray Florence Volatron Caroline Salzemann Anh‐Tu Ngo Pierre‐Antoine Albouy Anna Proust Christophe Petit 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(2):220-228
In the present article, the successful coassembly of spherical 6.2 nm maghemite (γ‐Fe2O3) nanocrystals and giant polyoxometalates (POMs) such as 2.9 nm {Mo132} is demonstrated. To do so, colloidal solutions of oleic acid‐capped γ‐Fe2O3 and long‐chain alkylammonium‐encapsulated {Mo132} dispersed in chloroform are mixed together and supported self‐organized binary superlattices are obtained upon the solvent evaporation on immersed substrates. Both electronic microscopy and small angles X‐ray scattering data reveal an AB‐type structure and an enhanced structuration of the magnetic nanocrystals (MNCs) assembly with POMs in octahedral interstices. Therefore, {Mo132} acts as an efficient binder constituent for improving the nanocrystals ordering in 3D films. Interestingly, in the case of didodecyldimethylammonium (C12)‐encapsulated POMs, the long‐range ordered binary assemblies are obtained while preserving the nanocrystals magnetic properties due to weak POMs–MNCs interactions. On the other hand, POMs of larger effective diameter can be employed as spacer blocks for MNCs as shown by using {Mo132} capped with dioctadecyldimethylammonium (C18) displaying longer chains. In that case, it is shown that POMs can also be used for fine‐tuning the dipolar interactions in γ‐Fe2O3 nanocrystal assemblies. 相似文献
323.
Surface Passivation for Reliable Measurement of Bulk Electronic Properties of Heterojunction Devices
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Benjamin Bissig Carlos Guerra‐Nunez Romain Carron Shiro Nishiwaki Fabio La Mattina Fabian Pianezzi Paolo A. Losio Enrico Avancini Patrick Reinhard Stefan G. Haass Martina Lingg Thomas Feurer Ivo Utke Stephan Buecheler Ayodhya N. Tiwari 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(38):5339-5346
Quantum efficiency measurements of state of the art Cu(In,Ga)Se2 (CIGS) thin film solar cells reveal current losses in the near infrared spectral region. These losses can be ascribed to inadequate optical absorption or poor collection of photogenerated charge carriers. Insight on the limiting mechanism is crucial for the development of more efficient devices. The electron beam induced current measurement technique applied on device cross‐sections promises an experimental access to depth resolved information about the charge carrier collection probability. Here, this technique is used to show that charge carrier collection in CIGS deposited by multistage co‐evaporation at low temperature is efficient over the optically active region and collection losses are minor as compared to the optical ones. Implications on the favorable absorber design are discussed. Furthermore, it is observed that the measurement is strongly affected by cross‐section surface recombination and an accurate determination of the collection efficiency is not possible. Therefore it is proposed and shown that the use of an Al2O3 layer deposited onto the cleaved cross‐section significantly improves the accuracy of the measurement by reducing the surface recombination. A model for the passivation mechanism is presented and the passivation concept is extended to other solar cell technologies such as CdTe and Cu2(Zn,Sn)(S,Se)4. 相似文献
324.
Andreas W. Schell Mikael Svedendahl Romain Quidant 《Advanced materials (Deerfield Beach, Fla.)》2018,30(14)
Understanding the properties of novel solid‐state quantum emitters is pivotal for a variety of applications in research fields ranging from quantum optics to biology. Recently discovered defects in hexagonal boron nitride are especially interesting, as they offer much desired characteristics such as narrow emission lines and photostability. Here, the dependence of the emission on the excitation wavelength is studied. It is found that, in order to achieve bright single‐photon emission with high quantum efficiency, the excitation wavelength has to be matched to the emitter. This is a strong indication that the emitters possess a complex level scheme and cannot be described by a simple two or three‐level system. Using this excitation dependence of the emission, further insight to the internal level scheme is gained and it is demonstrated how to distinguish different emitters both spatially as well as in terms of their photon correlations. 相似文献
325.
The influence of the hydraulic retention time (HRT) on the start-up phase of a methanogenic inverse turbulent bed bioreactor was investigated. Two identical reactors were monitored, the only differing parameter being the HRT: one of the reactors was fed with a diluted wastewater at a constant HRT of 1 day, the organic loading rate (OLR) being increased by decreasing the substrate dilution; the second reactor was fed at a constant influent concentration of 20 g COD L(-1), the OLR being increased by decreasing the HRT from 40 days to 1 day. After 45 days of start-up, both reactors were operated at an OLR of 20 g COD L(-1)d(-1) and a HRT of 1 day. However, strong differences were observed on biofilm growth. In the reactor operated at a constant short HRT, biofilm concentration was 4.5 as high as in the reactor operated at an increasing HRT. This difference was attributed to the competition between planktonic and biofilm microorganisms in the latter reactor, whereas suspended biomass was quickly washed out in the former reactor because of the low HRT. 相似文献
326.
Romain Jamard Antoine Latour Jeremie SalomonPhilippe Capron Audrey Martinent-Beaumont 《Journal of power sources》2008
In this study, direct borohydride fuel cells (DBFCs) potentialities are evaluated. These emerging systems make it possible to reach maximum powers of about 200 mW cm−2 at room temperature and ambient air (natural convection) with high concentrated borohydride solutions. On the other hand, a part of borohydride hydrolyses during cell operating which leads to hydrogen formation and fuel loss: the practical capacity represents about only 18% of the theoretical one. In order to improve fuel efficiency, thiourea is tested as an inhibitor of the catalytic hydrolysis associated with BH4− electro-oxidation on Pt. The practical capacity is drastically improved: it represents about 64% of the theoretical one. Against, electrochemical performances (I–E curves) are affected by the presence of thiourea. 相似文献
327.
Alexandre Moeuf Samir Lamouri Robert Pellerin Simon Tamayo-Giraldo Estefania Tobon-Valencia Romain Eburdy 《国际生产研究杂志》2020,58(5):1384-1400
SMEs, as prominent actors in industry, must meet more and more complex customer expectations. Recently, the concept of Industry 4.0 has emerged. This new approach enables the control of production processes by providing real-time synchronisation of flows and by enabling the production of unitary and customised products. Our research goal is to identify Industry 4.0 risks, opportunities and critical success factors with regards to the industrial performance of SMEs. The recent emergence of Industry 4.0 and the inherent difficulty of identifying detailed examples has not yet enabled a satisfactory statistical study to be conducted on Industry 4.0 cases in SMEs. To reach our research goal, we selected 12 experts to conduct a Delphi study supplemented by Régnier’s abacuses. Our study demonstrates that the major risks facing the adoption of Industry 4.0 in SMEs include a lack of expertise and a short-term strategy mindset. Our research also indicates that training is the most important factor for success, that managers have a prominent role in the success and/or failure of an Industry 4.0 project, and that SMEs should be supported by external experts. Lastly, Industry 4.0 offers a unique opportunity to redesign SME production processes and to adopt new business models. 相似文献
328.
Orsal G. Romain N. Artaud M.-C. Duchemin S. 《Electron Devices, IEEE Transactions on》1999,46(10):2098-2102
CuGaSe2 thin films have been grown by metalorganic chemical vapor deposition (MOCVD), from three organometallic precursors. Samples of about 1-2 μm thick are codeposited onto Pyrex and Mo-coated soda lime glass. A large range of compositions was investigated and characterized. Stoichiometric CuGaSe2 thin films are single-phased and their optical bandgap is about 1.68 eV. The features of the films are presented in relation with their composition. XRD spectra always exhibit a preferential orientation along the (112) plane. Secondary phases have been observed: Cu2Se for Cu-rich films, CuGa3Se5 for Ca-rich films. Observation of the morphology reveals larger polyhedral grains for Cu-rich films becoming platelet-shaped and tilted for Ga-rich compounds. The optical properties are also sensitive to the compositional changes and related to the eventual presence of binary phases. The gap increases with the Ga-content. The CuGa3Se5, phase exhibit a gap of about 1.85 eV. All the samples have a p-type conductivity 相似文献
329.
Camille Evrard Stphane Messina David Sefrioui ric Frouin Marie-Luce Auriault Romain Chautard Aziz Zaanan Marion Jaffrelot Christelle De La Fouchardire Thomas Aparicio Romain Coriat Julie Godet Christine Silvain Violaine Randrian Jean-Christophe Sabourin Rosine Guimbaud Elodie Miquelestorena-Standley Thierry Lecomte Valrie Moulin Lucie Karayan-Tapon Gaëlle Tachon David Tougeron 《International journal of molecular sciences》2022,23(8)
Deficient mismatch repair system (dMMR)/microsatellite instability (MSI) is found in about 5% of metastatic colorectal cancers (mCRCs) with a major therapeutic impact for immune checkpoint inhibitor (ICI) use. We conducted a multicentre study including all consecutive patients with a dMMR/MSI mCRC. MSI status was determined using the Pentaplex panel and expression of the four MMR proteins was evaluated by immunohistochemistry (IHC). The primary endpoint was the rate of discordance of dMMR/MSI status between primary tumours and paired metastases. We included 99 patients with a dMMR/MSI primary CRC and 117 paired metastases. Only four discrepancies (3.4%) with a dMMR/MSI primary CRC and a pMMR/MSS metastasis were initially identified and reviewed by expert pathologists and molecular biologists. Two cases were false discrepancies due to human or technical errors. One discordant case could not be confirmed due to the low level of tumour cells. The last case had a confirmed discrepancy with a dMMR/MSI primary CRC and a pMMR/MSS peritoneal metastasis. Our study demonstrated a high concordance rate of dMMR/MSI status between primary CRCs and their metastases. The analysis of one sample, either from the primary tumour or metastasis, with consistent dMMR and MSI status seems to be sufficient prior to treatment with ICI. 相似文献
330.
The packing of granular particles is investigated using a combined finite-discrete element approach. One of the aims of this
paper is to present an application of a recently improved numerical simulation technique for deformable granular material
with arbitrary shapes. Our study is focused on the influence of the effect of the particle shape on (1) the emergent properties
of a granular pack (packing density, coordination number, force distribution), and on (2) the spatial distribution of the
stress. A set of simulations that mimick the sedimentation process is carried out, with varying input parameters, such as
contact friction and particle shape. It is shown that the eccentricity of the particles not only significantly influences
the final density of the pack but also the distribution of the stress and the contact forces. The presence of surface friction
increases the amount of disorder within the granular system. Stress heterogeneities and force chain patterns propagate through
the particles more efficiently than for the frictionless systems. The results also suggest that for the monodisperse systems
investigated the coordination number is one of the factors that controls the distribution of the stress within a granular
medium. 相似文献