全文获取类型
收费全文 | 813篇 |
免费 | 30篇 |
专业分类
电工技术 | 4篇 |
综合类 | 1篇 |
化学工业 | 209篇 |
金属工艺 | 18篇 |
机械仪表 | 9篇 |
建筑科学 | 26篇 |
矿业工程 | 5篇 |
能源动力 | 23篇 |
轻工业 | 176篇 |
水利工程 | 5篇 |
石油天然气 | 3篇 |
无线电 | 48篇 |
一般工业技术 | 104篇 |
冶金工业 | 98篇 |
原子能技术 | 13篇 |
自动化技术 | 101篇 |
出版年
2023年 | 7篇 |
2022年 | 14篇 |
2021年 | 32篇 |
2020年 | 12篇 |
2019年 | 13篇 |
2018年 | 15篇 |
2017年 | 21篇 |
2016年 | 27篇 |
2015年 | 17篇 |
2014年 | 17篇 |
2013年 | 50篇 |
2012年 | 59篇 |
2011年 | 51篇 |
2010年 | 49篇 |
2009年 | 45篇 |
2008年 | 37篇 |
2007年 | 45篇 |
2006年 | 38篇 |
2005年 | 21篇 |
2004年 | 30篇 |
2003年 | 25篇 |
2002年 | 24篇 |
2001年 | 10篇 |
2000年 | 13篇 |
1999年 | 10篇 |
1998年 | 18篇 |
1997年 | 10篇 |
1996年 | 14篇 |
1995年 | 10篇 |
1994年 | 22篇 |
1993年 | 6篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1970年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有843条查询结果,搜索用时 15 毫秒
101.
Rositi Hugo Appadoo Owen Kevin Mestre Daniel Valarier Sylvie Ombret Marie-Claire Gadea-Deschamps Émilie Barret-Grimault Christine Lohou Christophe 《Multimedia Tools and Applications》2021,80(2):1945-1967
Multimedia Tools and Applications - Microsoft has recently released a mixed reality headset called HoloLens. This semi-transparent visor headset allows the user who wears it to view the projection... 相似文献
102.
Reviews the book, Manuel de gérontologie sociiale 2 by Jean Carette (1992). The Handbook of Social Gerontology 2 constitutes a practical complement of volume 1 which related to the social aspects of ageing and the retirement. Volume 2 relates mainly to the social intervention whose objective is to support the action and the collective mobilization individuals and associations of retirements. Using a 30-year experiment with groups of retirees, either in preparation of retirement, or in the collective action, the author approaches a new ground in gerontology. He proposes a new approach--social gerontology, (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
103.
This paper introduces the use of sets of multiple networks (bundled networks) to manage the variability due to different initialization parameters. This method makes it statistically impossible for the networks to be trapped in the same local minimum, and therefore allows better control of the confidence of the prediction eventually given. The spread of the forecasts given by these different networks can be used for prediction reliability purposes. An illustration of this usage is given with the El Niño phenomenon. 相似文献
104.
Balasubramanian Nagarajan Sylvie Castagne Zhongke Wang H.Y. Zheng Kartikeyan Nadarajan 《International Journal of Material Forming》2017,10(1):109-123
Flexible Pad Laser Shock Forming (FPLSF) is a new microforming process using laser-induced shock pressure and a hyperelastic flexible pad to induce high strain-rate (~105 s?1) plastic deformation on metallic foils to produce 3D microcraters. This paper studies the effect of two significant process parameters of FPLSF, flexible pad material and its thickness, on the deformation characteristics of the metal foils using experiments and finite element analysis. A finite element model is developed to simulate the FPLSF process. The stress-strain distribution across the foil and the flexible pad at different process stages of FPLSF are studied using FE analysis. Flexible pad materials including silicone rubber, polyurethane rubber, and natural rubber with thicknesses ranging between 300 μm and 3000 μm have been investigated in detail. Experimental results highlight that both the hardness and thickness of the flexible pad significantly influence the deformed crater geometry, thickness distribution across the formed crater and surface hardness at the crater surfaces. The experimental results are correlated with the stress-strain distributions from finite element analysis to study the underlying behaviors. 相似文献
105.
Camilo Castro López Xavier Lefebvre Nadège Brusselle-Dupend Marie-Hélène Klopffer Laurent Cangémi Sylvie Castagnet Jean-Claude Grandidier 《Journal of Materials Science》2016,51(8):3750-3761
This paper discusses the effect of porosity and hydrostatic pressure on diffusion kinetics and equilibrium water uptake in a semicrystalline fluoropolymer. Water sorption experiments at atmospheric pressure and under water pressures up to 250 MPa were carried out during 18 months at 40 °C on reference and porous samples. Porosity of samples was induced due to a cavitation process occurring at the highest triaxiality area of waisted and notched specimens during tensile tests. Water uptake was found to be very sensitive to porosity, showing an increase in samples with a high void fraction. On the other hand, water content decreased with increasing pressure suggesting a compaction of the porous space in which water can be stored. Two models describing this water uptake behaviour were considered. The first is a classical model which assumes that sorption occurs only by diffusion following Fick’s law. Fick’s model was found to be in agreement with the experimental results. A “Langmuir-type” sorption model was also proposed to describe water uptake in porous samples, considering a two-phase water transport mechanism: one portion of the absorbed water diffuses through the polymer matrix and the other portion is stored in voids. This model was implemented in a user subroutine using ABAQUS? software and simulations were confronted to experimental sorption curves showing satisfactory agreements. The potential of the Langmuir-type sorption model resides on its availability to be coupled to a poro-mechanical model, in order to improve the understanding of coupling between the mechanical behaviour and water sorption mechanism in a porous polymer. 相似文献
106.
Gwladys Perrais Sophie Derelle Laurent Mollard Jean-Paul Chamonal Gerard Destefanis Gilbert Vincent Sylvie Bernhardt Johan Rothman 《Journal of Electronic Materials》2009,38(8):1790-1799
The impulse response in frontside-illuminated mid-wave infrared HgCdTe electron avalanche photodiodes (APDs) has been measured
with localized photoexcitation at varying positions in the depletion layer. Gain measurements have shown an exponential gain,
with a maximum value of M = 5000 for the diffusion current at a reverse bias of V
b = 12 V. When the light was injected in the depletion layer, the gain was reduced as the injection approached the N+ edge
of the junction. The impulse response was limited by the diode series resistance–capacitance product, RC, due to the large capacitance of the diode metallization. Hence, the fall time is given by the RC constant, estimated as RC = 270 ps, and the rise time is due to the charging of the diode capacitance via the transit and multiplication of carriers
in the depletion layer. The latter varies between t
10–90 = 20 ps (at intermediate gains M < 500) and t
10–90 = 70 ps (at M = 3500). The corresponding RC-limited bandwidth is BW = 600 MHz, which yields a new absolute record in gain–bandwidth product of GBW = 2.1 THz. The increase
in rise time at high gains indicates the existence of a limit in the transit-time-limited gain–bandwidth product, GBW = 19 THz.
The impulse response was modeled using a one-dimensional deterministic model, which allowed a quantitative analysis of the
data in terms of the average velocity of electrons and holes. The fitting of the data yielded a saturation of the electron
and hole velocity of v
e = 2.3 × 107 cm/s and v
h = 1.0 × 107 cm/s at electric fields E > 1.5 kV/cm. The increase in rise time at high bias is consistent with the results of Monte Carlo simulations and can be
partly explained by a reduction of the electron saturation velocity due to frequent impact ionization. Finally, the model
was used to predict the bandwidth in diodes with shorter RC = 5 ps, giving BW = 16 GHz and BW = 21 GHz for x
j = 4 μm and x
j = 2 μm, respectively, for a gain of M = 100. 相似文献
107.
Mathieu Thevenot Sylvie Dousset Philippe Schmitt-Kopplin 《The Science of the total environment》2009,407(14):4297-4302
Diuron is frequently detected in some drinking water reservoirs under the Burgundy vineyards, where organic amendments are applied. The environmental effect of these amendments on pesticide transport is ambiguous: on the one hand it could enhance their retention by increasing soil organic carbon content; on the other hand, dissolved organic matter (DOM) could facilitate their transport. Elutions were performed using columns packed with glass beads in order to investigate DOM-diuron interactions, and the possible co-transport of diuron and DOM. Four organic amendments (A, B, C and D) were tested; C and D were sampled at fresh (F) and mature (M) stages. An increase in diuron leaching was observed only for A and DF amendments (up to 16% compared to the DOM-free blank samples), suggesting a DOM effect on diuron transport. These results could be explained by the higher DOM leaching for A and DF compared to B, CF, CM and DM increasing diuron-DOM interactions. These interactions seem to be related to the aromatic and aliphatic content of the DOM, determining formation of hydrogen and non-covalent bonds. The degree of organic matter maturity does not seem to have any effect with amendment C, while a reduction in diuron leaching is observed between DF and DM. After equilibrium dialysis measurement of diuron-DOM complexes, it appeared that less than 3% of the diuron applied corresponded to complexes with a molecular weight > 1000 Da. Complexes < 1000 Da could also take part in this facilitated transport. 相似文献
108.
Agglomeration for heap leaching: Equipment design, agglomerate quality control, and impact on the heap leach process 总被引:1,自引:0,他引:1
In preparation for demonstration heaps, the optimum conditions for agglomeration were determined through testwork. Producing a narrow size distribution of agglomerates in which few agglomerates were smaller than a rice grain, controlling the moisture content to 8–10%, and adding 0.3 kg/t of a commercial polymeric binder were the most important conditions for creating a porous packed bed, as determined from column tests.In a continuous operation, these conditions could be controlled effectively via the ore and solution feed rates to achieve a residence time of 2 min. This ensured that very large, poorly-shaped agglomerates formed before 1.5 min were fragmented into mid-size, well-shaped agglomerates, as well as allowed consolidation of small agglomerates into mid-size ones. Although the residence time of 2 min may not be the optimum for other ores, this study proved that the residence time was the same in a batch or continuous operation regardless of ore type or size distribution.Under the same conditions of agglomeration, the demonstration heaps did not validate the results of the column tests. The heaps were more compact because of the absence of structural support otherwise present in columns through the wall effect. These results highlight the value of demonstration heaps in the scale-up process. 相似文献
109.
How do people work when they are collaborating to write a document? What kind of tools do they use and, in particular, do they resort to groupware for this task? Forty-one people filled out a questionnaire placed on the World Wide Web. In spite of the existence of specialized collaborative writing tools, most respondents reported using individual word processors and email as their main tools for writing joint documents. Respondents noted the importance of functions such as change tracking, version control, and synchronous work for collaborative writing tools. This study also confirmed the great variability that exists between collaborative writing projects, whether it be group membership, management, writing strategy, or scheduling issues. 相似文献
110.
Rats with medial prefrontal cortical lesions were tested in a modified water maze navigation task. In Stage 1, the rats were trained to locate a hidden platform from a single start location. They were then subjected to a series of trials during which a second start position was used (Stage 2). In Stage 3, the rats had to navigate to a new goal location from the 2 experienced start positions. Stage 4 required the rats to navigate to the same goal as in Stage 3, starting from 4 distinct positions. Finally, a single probe trial with no platform was conducted. Rats with prefrontal lesions were impaired only during Stage 4. This deficit was specific to the 2 start positions newly introduced during this stage, suggesting a dysfunction of planning processes. This impairment might result from a working memory deficit, precluding the animal from forming an adequate representation of the whole course of movements required to reach the platform. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献