全文获取类型
收费全文 | 10002篇 |
免费 | 589篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 102篇 |
综合类 | 26篇 |
化学工业 | 2346篇 |
金属工艺 | 248篇 |
机械仪表 | 175篇 |
建筑科学 | 433篇 |
矿业工程 | 48篇 |
能源动力 | 290篇 |
轻工业 | 934篇 |
水利工程 | 118篇 |
石油天然气 | 22篇 |
无线电 | 681篇 |
一般工业技术 | 2131篇 |
冶金工业 | 1564篇 |
原子能技术 | 56篇 |
自动化技术 | 1427篇 |
出版年
2023年 | 110篇 |
2022年 | 190篇 |
2021年 | 301篇 |
2020年 | 228篇 |
2019年 | 247篇 |
2018年 | 283篇 |
2017年 | 269篇 |
2016年 | 321篇 |
2015年 | 241篇 |
2014年 | 406篇 |
2013年 | 671篇 |
2012年 | 563篇 |
2011年 | 799篇 |
2010年 | 533篇 |
2009年 | 505篇 |
2008年 | 555篇 |
2007年 | 515篇 |
2006年 | 413篇 |
2005年 | 373篇 |
2004年 | 324篇 |
2003年 | 288篇 |
2002年 | 248篇 |
2001年 | 145篇 |
2000年 | 134篇 |
1999年 | 129篇 |
1998年 | 186篇 |
1997年 | 149篇 |
1996年 | 119篇 |
1995年 | 122篇 |
1994年 | 109篇 |
1993年 | 85篇 |
1992年 | 86篇 |
1991年 | 42篇 |
1990年 | 49篇 |
1989年 | 59篇 |
1988年 | 57篇 |
1987年 | 68篇 |
1986年 | 53篇 |
1985年 | 76篇 |
1984年 | 63篇 |
1983年 | 52篇 |
1982年 | 60篇 |
1981年 | 38篇 |
1980年 | 43篇 |
1979年 | 30篇 |
1978年 | 37篇 |
1977年 | 37篇 |
1976年 | 35篇 |
1975年 | 22篇 |
1973年 | 16篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Bhuvanesh Gupta Jns Hilborn Christopher Plummer Isabelle Bisson Peter Frey 《应用聚合物科学杂志》2002,85(9):1874-1880
Graft polymerization of acrylic acid onto plasma‐treated poly(ethylene terephthalate) (PET) films was used to prepare surfaces suitable for collagen immobilization by dip‐coating. Such surfaces could be used as matrices for smooth muscle cell cultures in tissue engineering. Contact angle measurements showed that plasma‐treated and grafted PET films undergo considerable surface reorganization during storage under ambient conditions. However, after collagen immobilization the contact angle remained relatively stable. The amount of collagen initially attached to the film surface increased with increasing poly(acrylic acid) graft density, but subsequent washing in water led to significant collagen loss. This loss could nevertheless be substantially reduced by thermal crosslinking of the collagen in the range 110–130 °C. Atomic force microscopy (AFM) observations suggested that the washed crosslinked collagen has a very similar structure to that of the un‐crosslinked collagen. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1874–1880, 2002 相似文献
92.
Claire E. Gerrard John McCall George M. Coghill Christopher Macleod 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2014,18(10):1899-1912
The Artificial Reaction Network (ARN) is a Cell Signalling Network inspired connectionist representation belonging to the branch of A-Life known as Artificial Chemistry. Its purpose is to represent chemical circuitry and to explore computational properties responsible for generating emergent high-level behaviour associated with cells. In this paper, the computational mechanisms involved in pattern recognition and spatio-temporal pattern generation are examined in robotic control tasks. The results show that the ARN has application in limbed robotic control and computational functionality in common with Artificial Neural Networks. Like spiking neural models, the ARN can combine pattern recognition and complex temporal control functionality in a single network, however it offers increased flexibility. Furthermore, the results illustrate parallels between emergent neural and cell intelligence. 相似文献
93.
M Mahbubul Hassan Christopher J Hawkyard 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2002,77(7):834-841
Combined oxidation with ozone and Fenton's reagent (‘Fentozone’ process) for decolourisation of aqueous dyes was studied and compared with traditional Fenton's reagent. Although the ‘Fentozone’ process was found to be effective at a wide range of pH values, the maximum colour removal was achieved at pH 4. The effect of pre‐ozonation on colour removal efficiency of aqueous dyestuffs in the subsequent treatment with Fenton's reagent was investigated. The reaction kinetics using water‐soluble acid and reactive dyes were also studied. Our experimental results show that pre‐ozonation can considerably accelerate decomposition of dyestuffs in the subsequent treatment with Fenton's reagent. Different concentrations of ferrous sulfate were used to investigate their influences on the removal of colour. The rate of reaction increased with increasing doses of ferrous sulfate. © 2002 Society of Chemical Industry 相似文献
94.
Phosphatidic acid (PtdOH) and lysophosphatidic acid (lysoPtdOH) have been shown to enhance T-lymphocyte function. However,
the FA preference and influence of acyl-CoA binding proteins on lysoPtdOH and PtdOH biosynthesis are not known. Therefore,
we determined glycerol-3-phosphate acyltransferase (GPAT) and lysophosphatidic acid acyltransferase (LAT) activity in rat
T-lymphocyte and liver membrane preparations in the presence of palmitoyl-CoA and oleoyl-CoA with or without BSA. We found
two different properties of GPAT and LAT in whole T-lymphocyte membrane preparations relative to liver. First, T-lymphocyte
basal GPAT and LAT activities were similar, whereas in liver membranes LAT activity was 10-fold higher than GPAT. Second,
T-lymphocyte LAT, but not GPAT, activity was inducible (fivefold) by the addition of albumin in the presence of palmitoyl-CoA
but not oleoyl-CoA. In contrast, albumin stimulated GPAT, but not LAT, activity in liver membranes in the presence of palmitoyl-CoA.
These results show, for the first time, that T-lymphocyte LAT activity can be increased by the presence of an acyl-CoA binding
protein, which may indicate a new important control mechanism for regulating intracellular lysoPtdOH and PtdOH levels in T-lymphocytes. 相似文献
95.
A comprehensive kinetic model describing photopolymerization is developed which allows variation of temperature, species concentrations, and light intensity through the thickness of a photopolymerized film. Heat and mass transfer effects are included, as is the generation of heat by both reaction and light absorption. In addition to initiation, propagation, and termination mechanisms, both primary radical termination and inhibition are incorporated into the model. The possible presence and diffusion of an inert solvent are also accounted for. Thus, the model is useful for examining complex polymerization kinetics and behavior in industrially and commercially important thick film photopolymerizations, such as the curing of contact lenses, dental restorative materials, photolithographic resists, and optoelectronic coatings. The comprehensive model is used to predict polymerization rate, temperature, and conversion profiles in a variety of systems. The effects of heat generation and the thermal boundary conditions are explored, with the result that heat generation in thick samples leads to greatly increased conversions approaching 100 percent. Increased temperature in these samples also may lead to the appearance of two rate maxima, with the first due to the temperature increase and the second caused by the autoacceleration process. The magnitude of the temperature increase, along with the resultant effects, is more pronounced in insulated systems. 相似文献
96.
Consolidation Behavior of Flocculated Alumina Suspensions 总被引:2,自引:0,他引:2
Lennart Bergström Christopher H. Schilling Ilhan A. Aksay 《Journal of the American Ceramic Society》1992,75(12):3305-3314
The consolidation behavior of flocculated alumina suspensions has been analyzed as a function of the interparticle energy. Consolidation was performed by a centrifugal force field or by gravity, and both the time-dependent and equilibrium density profiles were measured by a gamma-ray absorption technique. The interparicle energy at contact was controlled by adsorbing fatty acids of varying molecular weight at the alumina/decalin interface. We found that strongly attractive interactions result in a particle network which resists consolidation and shows compressible behavior over a large stress range. The most weakly flocculated suspension showed an essentially incompressible, homogeneous density profile after consolidation at different centrifugal speeds. We also found a significant variation in the maximum volume fraction, φm , obtained, with φm ∼ 0.54 for the most strongly flocculated suspension to φm ∼ 0.63 for the most weakly flocculated suspension. The compresive yield stresses show a behavior which can be fitted to a modified power law. In this paper, we discuss possible correlations between the fitting parameters and physical properties of the flocculated suspensions. 相似文献
97.
Despite significant advances in water based surface coating technology, the presence of surfactants in emulsion polymer binders leads to loss of performance after prolonged immersion in water, relative to solvent based coatings that are free of surfactant impurities. This study begins with water uptake evaluation of a range of emulsion polymer binders. A carboxylated styrene butadiene rubber latex (c-SBR) performed best in the latter evaluations and was selected for the formulation of an exterior grade paint and construction of a mathematical model to predict water uptake of the dry film. The c-SBR was then compounded with a range of inorganic fillers and water uptake and tensile properties were evaluated. Talc was found to be the best performing filler, and was used in a three factorial central composite design study where the simultaneous effects of talc, titanium dioxide and phenolic stabiliser on water up take were evaluated and fitted to response equations. A quadratic model was found to provide the most accurate prediction of effects associated with interactions between talc and TiO2. Certain combinations of talc and titanium dioxide were found to be synergistic in reducing the water uptake. This was considered to be associated with a packing effect stemming from the vast difference in particle size between talc and titanium dioxide particles. An optimised formulation was finally prepared to meet one of the final formulation objectives; i.e., minimised water uptake. Preparation of such a formulation showed that the predicted and measured water uptake responses were in excellent agreement. This study illustrates the effectiveness of statistical experimental design methods in predicting the water uptake characteristics of water-based coatings. 相似文献
98.
Gerhard Maier Vendula Knopfova Brigitte Voit Pham Huu Ly Bui Tien Dung Do Bich Thanh 《大分子材料与工程》2004,289(10):927-932
Summary: Segmented block copolymers, consisting of non‐polar soft segments from hydroxyl‐terminated liquid natural rubber (HTNR) and polar hard segments from α,ω‐diisocyanato telechelics obtained by “criss‐cross”‐cycloaddition, have been synthesized. The block copolymer formation took place under relatively mild reaction conditions at 80 °C in dichloroethane in the presence of dibutyltin dilaurate as a catalyst. The resulting block copolymers were characterized by spectroscopic techniques (1H NMR, FTIR, UV‐vis spectroscopy) as well as GPC for molar mass determination. The block copolymers were compression molded in a hot stage press, and the resulting samples were characterized by DSC and stress‐strain measurement. The solubility and phase morphology of the materials have also been studied.
99.
Carl C. Gryte Christopher Koroneos Anil Agarwal Arie Hochberg 《Polymer Engineering and Science》1980,20(7):478-484
Graft copolymers were prepared by irradiation of poly(oxyethylene), PEO, aqueous solutions in presence of acrylic acid. Chain transfer to PEO controls the graft length, the measured chain transfer constant of the acrylic acid radicals to PEO being 4.11 × 10?4 at 25°C. The drag reduction characteristics of the graft copolymers were measured in the Reynolds number range 104–105 in a smooth-walled tube, 0.635 cm inside diameter. The drag reduction falls to near zero as the solution pH is lowered to 3, evidence of the formation of a PEO-poly(acrylic acid) coacervate. 相似文献
100.
In the paper, the characters and fields were introduced for utilizing the Series/Parallel Switch (SPS). The circuit principle of the SPS technology was analyzed in detailed, explained and illuminated. We understood clearly the difference between SPS and single-phase transformator by the figure and table. Finally, it summarized that the main characters of SPS. 相似文献