全文获取类型
收费全文 | 1411篇 |
免费 | 53篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 14篇 |
综合类 | 1篇 |
化学工业 | 382篇 |
金属工艺 | 51篇 |
机械仪表 | 29篇 |
建筑科学 | 64篇 |
矿业工程 | 1篇 |
能源动力 | 52篇 |
轻工业 | 171篇 |
水利工程 | 5篇 |
无线电 | 147篇 |
一般工业技术 | 282篇 |
冶金工业 | 56篇 |
原子能技术 | 10篇 |
自动化技术 | 201篇 |
出版年
2024年 | 2篇 |
2023年 | 10篇 |
2022年 | 30篇 |
2021年 | 52篇 |
2020年 | 25篇 |
2019年 | 26篇 |
2018年 | 26篇 |
2017年 | 22篇 |
2016年 | 32篇 |
2015年 | 27篇 |
2014年 | 52篇 |
2013年 | 109篇 |
2012年 | 81篇 |
2011年 | 132篇 |
2010年 | 97篇 |
2009年 | 83篇 |
2008年 | 84篇 |
2007年 | 63篇 |
2006年 | 66篇 |
2005年 | 49篇 |
2004年 | 38篇 |
2003年 | 41篇 |
2002年 | 37篇 |
2001年 | 20篇 |
2000年 | 19篇 |
1999年 | 22篇 |
1998年 | 14篇 |
1997年 | 31篇 |
1996年 | 15篇 |
1995年 | 22篇 |
1994年 | 15篇 |
1993年 | 12篇 |
1992年 | 9篇 |
1991年 | 13篇 |
1990年 | 4篇 |
1989年 | 10篇 |
1988年 | 4篇 |
1987年 | 12篇 |
1985年 | 10篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 6篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1973年 | 3篇 |
1972年 | 1篇 |
排序方式: 共有1466条查询结果,搜索用时 0 毫秒
91.
Vincent Bizet Xavier Pannecoucke Jean‐Luc Renaud Dominique Cahard 《Advanced Synthesis \u0026amp; Catalysis》2013,355(7):1394-1402
The ruthenium–2‐propanol combination was found to transform γ‐trifluoromethylated allylic alcohols and β‐trifluoromethylated enones into the corresponding saturated alcohols in excellent yields via a one‐pot tandem process involving isomerization and transfer hydrogenation(s). High stereospecificity was demonstrated and evidence for two mechanistic pathways is provided. The method was applied to a rapid synthesis of trifluoromethylated citronellol. 相似文献
92.
Caroline Celle Clément Suspène Jean-Pierre Simonato Stéphane Lenfant Marc Ternisien Dominique Vuillaume 《Organic Electronics》2009,10(1):119-126
In this paper we show that thiolated self-assembled monolayers (SAMs) can be used to anchor source–drain gold electrodes on the substrate, leading to excellent electrical performances of the organic field-effect transistor (OFET) on a par with those using a standard electrode process. Using an amorphous semiconductor and a gate dielectric functionalized with SAMs bearing different dipole moments, we demonstrate that we can tune the threshold voltage alone, while keeping nearly unchanged the other electrical properties (hole carrier mobility, Ion/Ioff ratio, subthreshold swing). This differs from previous studies for which SAMs functionalization induced significant changes in all the OFET electrical performances. This result opens doors to design organic circuits using reproducible amorphous semiconductor based OFETs for which only the threshold voltage can be tuned on demand. 相似文献
93.
Jie Li Laurent Fraikin Thierry Salmon Lyes Bennamoun Dominique Toye Raphael Schreinemachers 《Drying Technology》2013,31(6):704-712
This work is part of a project aiming to develop a renewable fuel for gasification purposes, through convective drying of sludge/wood mixtures. The first step consists of characterizing the behavior of sawdust/sludge mixtures during the application of convective drying. The influence of the mixing step (no mixing versus 30 s at 40 rpm), as well as the sawdust : sludge ratio (1:9, 2:8, 3:7, and 4:6 on a dry basis) and the effect of drying temperature (50, 80, and 110°C) were investigated. In this study, X-ray tomography, a noninvasive imaging technique, is used to assess changes in the volume, void, and exchange surface at the beginning and the end of the drying process. Results first confirm the importance of the mixing step on the drying behavior: the drying rate of the mixed sludge is lower than that of the original sludge. Nevertheless, the addition of sawdust is shown to have a positive impact on the drying process from a mass ratio of 2:8, with drying rates higher than that of the original sludge. With increasing amounts of sawdust, the initial and final bed volumes, initial and final total exchange surfaces, and initial void fraction increase linearly, but the bed volume shrinkage and final void fraction decrease linearly. 相似文献
94.
Polynomial ranges are commonly used for numerically solving polynomial systems with interval Newton solvers. Often ranges are computed using the convex hull property of the tensorial Bernstein basis, which is exponential size in the number n of variables. In this paper, we consider methods to compute tight bounds for polynomials in n variables by solving two linear programming problems over a polytope. We formulate a polytope defined as the convex hull of the coefficients with respect to the tensorial Bernstein basis, and we formulate several polytopes based on the Bernstein polynomials of the domain. These Bernstein polytopes can be defined by a polynomial number of halfspaces. We give the number of vertices, the number of hyperfaces, and the volume of each polytope for n=1,2,3,4, and we compare the computed range widths for random n-variate polynomials for n?10. The Bernstein polytope of polynomial size gives only marginally worse range bounds compared to the range bounds obtained with the tensorial Bernstein basis of exponential size. 相似文献
95.
D'Humières D Ginzburg I Krafczyk M Lallemand P Luo LS 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2002,360(1792):437-451
This article provides a concise exposition of the multiple-relaxation-time lattice Boltzmann equation, with examples of 15-velocity and 19-velocity models in three dimensions. Simulation of a diagonally lid-driven cavity flow in three dimensions at Re = 500 and 2000 is performed. The results clearly demonstrate the superior numerical stability of the multiple-relaxation-time lattice Boltzmann equation over the popular lattice Bhatnagar-Gross-Krook equation. 相似文献
96.
Chrysoula C Tassou Constantinos Z Katsaboxakis Dominique MR Georget Mary L Parker Keith W Waldron Andrew C Smith Efstathios Z Panagou 《Journal of the science of food and agriculture》2007,87(6):1123-1131
The effect of calcium chloride (CaCl2)(5 gL?1) and sodium chloride (NaCl) concentration (40, 60 and 8 gL?1) on the microbiological and mechanical properties of naturally black olives of cv. Conservolea in brines was studied. In 40 and 60 g L?1 brines the growth of lactic acid bacteria was favoured over that of yeasts, resulting in rather complete lactic acid fermentation as indicated by high free acidity (9.8–11.5 g lactic acid L?1) and low pH (3.7–3.8). At 80 g L?1 brine, yeasts were the dominant members of the microflora, rendering a product with lower acidity (8 g lactic acid L?1) and higher pH (4.3–4.5). In the presence of CaCl2 there was a consistent increase in the depth of the peripheral region in which cell wall breakage occurred. When cells separated, perforated walls were observed at sites associated with plasmodesmata. The flesh was strongest and stiffest when CaCl2 was added to olives treated with 40 g L?1 brine, consistent with cell wall breakage being the predominant mode of failure. The only observed effect on the mechanical properties of the skin was a stiffening at 60 g L?1 brine on addition of CaCl2. Copyright © 2007 Society of Chemical Industry 相似文献
97.
Manickam Minakshi Pritam Singh Dominique Appadoo Danielle E. Martin 《Electrochimica acta》2011,(11):A86
LiNiPO4 belongs to a family of olivine type compounds, with members LiMPO4 where M = Fe, Mn, Co or Ni are transition metals. The lithium nickel phosphate was prepared and characterized in order to evaluate a new potential cathode material for our ongoing research in aqueous rechargeable batteries. Annealing the final product is critical in obtaining the stoichiometric LiNiPO4 pure phase; conventional cooling to a room temperature leads to an indication of Li3PO4 and NiO secondary phases as impurities. The synchrotron infrared radiation (SR-IR) as a source for IR spectroscopy pins down the differences in the chemical bonding for annealed and conventional cooled LiNiPO4 samples. The cyclic voltammetric and galvanostatic studies showed annealed LiNiPO4 is electrochemically active from which lithium ions can be de-intercalated during oxidation process leading to an amorphous NiPO4 and a minor product of nickel(II) hydroxide (β-NiOOH). During subsequent reduction, lithium ions are not fully intercalated, however, the structure is reversible and adequate for multiple cycles. The high potential in LiNiPO4 looks to be very attractive in terms of high energy density, given the efficiency is improved. 相似文献
98.
This paper reports the structural investigation of a series of in situ spruce lignins in wood, thermomechanical pulp (TMP) and the corresponding bleached (BTMP) and photoyellowed (YBTMP) samples. This was achieved by using an original two-step degradative technique, thioacidolysis followed by Raney nickel desulfuration. The determination of thioacidolysis monomeric and dimeric products allowed an estimate of various lignin building units and interunit bonds, respectively. It was observed that the thermomechanical and bleaching treatments did not affect spruce lignin structure to an appreciable extent. On the contrary, the photoyellowing treatment caused marked structural changes in lignin, particularly when run in severe conditions. These changes were essentially a decrease in the amount of β-O-4 and β-1 interunit bonds and a relative increase in catechol units and in vanillin end-groups. 相似文献
99.
Nabil Mameri Farid Halet Madani Drouiche Hocine Grib Hakim Lounici Djamila Belhocine Andr Pauss Dominique Piron 《加拿大化工杂志》2000,78(3):590-595
Olive oil production requires important quantities of washing water containing low oil concentrations, but classical processes used to recover or to eliminate this oil are ineffective. This study presents a membrane technique to treat olive oil mill washing water using different commercial ultrafiltration membranes: one organic (PCI) and two ceramic (Ceraver) membranes. The influence of the hydrodynamic parameters (transmembrane pressure and flow rate) and the cut‐off membranes on the efficiency of the ultrafiltration process was evaluated, and it was shown the organic PCI membrane could reduce pollution due to organic matter by decreasing the value of the Chemical oxygen demand by about 90%. Moreover, the nature of the ultrafine pore membrane appeared to be an important parameter which may strongly increase or decrease the capacity of the membrane. The membrane cut‐off did not have a strong influence on the performance of the process but if the membrane pores were too large the stability of the dynamically formed membrane decreased at transmembrane pressures greater than 0.2 MPa. 相似文献
100.
Krzysztof Stanczyk Hak Soo Kim C. Sayag Dominique Brodzki Gérald Djéga‐Mariadassou 《Catalysis Letters》1998,53(1-2):59-64
Oxynitrides of early transition metals are bifunctional catalysts active in hydrodenitrogenation (HDN). The strength of the hydrogenating function and the acidic properties of molybdenum and niobium oxynitrides were investigated, as well as the inhibiting effect of ammonia and the effect of solvent (cyclohexane or tetradecane) on HDN of 1,2,3,4‐tetrahydroquinoline (1–4 THQ). Even under high hydrogen pressure (4.5 MPa) the reaction was found to be able to proceed without hydrogenation of the aromatic cycle of 1–4 THQ before C–N bond scission, which is not the case over sulfided NiMo supported catalysts in HDN. Experiments in presence of ammonia permitted to support a bifunctional dual site concept. This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献