全文获取类型
收费全文 | 1948篇 |
免费 | 112篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 18篇 |
化学工业 | 513篇 |
金属工艺 | 36篇 |
机械仪表 | 41篇 |
建筑科学 | 60篇 |
矿业工程 | 3篇 |
能源动力 | 70篇 |
轻工业 | 289篇 |
水利工程 | 17篇 |
石油天然气 | 10篇 |
无线电 | 129篇 |
一般工业技术 | 331篇 |
冶金工业 | 125篇 |
原子能技术 | 25篇 |
自动化技术 | 394篇 |
出版年
2024年 | 7篇 |
2023年 | 34篇 |
2022年 | 103篇 |
2021年 | 112篇 |
2020年 | 68篇 |
2019年 | 88篇 |
2018年 | 72篇 |
2017年 | 77篇 |
2016年 | 75篇 |
2015年 | 59篇 |
2014年 | 110篇 |
2013年 | 152篇 |
2012年 | 144篇 |
2011年 | 147篇 |
2010年 | 92篇 |
2009年 | 98篇 |
2008年 | 96篇 |
2007年 | 87篇 |
2006年 | 65篇 |
2005年 | 49篇 |
2004年 | 42篇 |
2003年 | 43篇 |
2002年 | 33篇 |
2001年 | 15篇 |
2000年 | 12篇 |
1999年 | 13篇 |
1998年 | 31篇 |
1997年 | 30篇 |
1996年 | 20篇 |
1995年 | 14篇 |
1994年 | 11篇 |
1993年 | 20篇 |
1992年 | 3篇 |
1991年 | 3篇 |
1990年 | 10篇 |
1989年 | 1篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 3篇 |
1972年 | 1篇 |
1971年 | 2篇 |
排序方式: 共有2061条查询结果,搜索用时 15 毫秒
61.
Alejandro Lapunzina 《Journal of Architectural Education》2013,67(3):152-158
This project for the Matteson Public Library was developed through the utilization of three architectural language elements that defined the varied spaces required by the competition program: a large, light roof floating over the building, a system of brass columns defining a rhythmically punctuated space, and a non-structural wall creating the outer skin of the building. The poetically inflected relationship between these three elements articulates and defines the spaces of the library, generating high spatial tension at the corner of the site. As expected, the Community Meeting Room occupies this prominent urban position. 相似文献
62.
63.
Hydrolytic degradation of nanocomposites based on poly(l‐lactic acid) and layered double hydroxides modified with a model drug 下载免费PDF全文
Hydrolytic degradation of a nanocomposite of poly(L‐lactic acid), PLA, and a layered double hydroxide (LDH) modified with the drug 4‐biphenyl acetic acid (Bph) has been studied. PLA/LDH‐Bph nanocomposite was prepared by solvent casting with 5 wt % of drug modified LDH and the hydrolytic degradation was carried out in a PBS solution at pH 7.2 and 37 °C. Neat PLA with 5 wt % 4‐biphenyl acetic acid was studied as reference material (PLA/Bph). The materials were studied by WAXS, TEM, TGA, DSC, SEM, FTIR, SEC and contact angle measurements. For PLA/Bph, an acid catalytic effect, caused by the drug, accelerates PLA mass loss. However, for PLA/LDH‐Bph, the presence of LDH produces a barrier effect that initially reduces the diffusion of the oligomers produced during hydrolytic degradation. DSC results demonstrate that Bph induces faster PLA crystallization and this effect is reduced in PLA/LDH‐Bph nanocomposites because of their lower drug content. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43648. 相似文献
64.
Emmanuel Vázquez-Mayorga ángel G. Díaz-Sánchez Ruben K. Dagda Carlos A. Domínguez-Solís Raul Y. Dagda Cynthia K. Coronado-Ramírez Alejandro Martínez-Martínez 《International journal of molecular sciences》2016,17(8)
Mutations the in human DJ-1 (hDJ-1) gene are associated with early-onset autosomal recessive forms of Parkinson’s disease (PD). hDJ-1/parkinsonism associated deglycase (PARK7) is a cytoprotective multi-functional protein that contains a conserved cysteine-protease domain. Given that cysteine-proteases can act on both amide and ester substrates, we surmised that hDJ-1 possessed cysteine-mediated esterase activity. To test this hypothesis, hDJ-1 was overexpressed, purified and tested for activity towards 4-nitrophenyl acetate (pNPA) as µmol of pNPA hydrolyzed/min/mg·protein (U/mg protein). hDJ-1 showed maximum reaction velocity esterase activity (Vmax = 235.10 ± 12.00 U/mg protein), with a sigmoidal fit (S0.5 = 0.55 ± 0.040 mM) and apparent positive cooperativity (Hill coefficient of 2.05 ± 0.28). A PD-associated mutant of DJ-1 (M26I) lacked activity. Unlike its protease activity which is inactivated by reactive oxygen species (ROS), esterase activity of hDJ-1 is enhanced upon exposure to low concentrations of hydrogen peroxide (<10 µM) and plateaus at elevated concentrations (>100 µM) suggesting that its activity is resistant to oxidative stress. Esterase activity of DJ-1 requires oxidation of catalytic cysteines, as chemically protecting cysteines blocked its activity whereas an oxido-mimetic mutant of DJ-1 (C106D) exhibited robust esterase activity. Molecular docking studies suggest that C106 and L126 within its catalytic site interact with esterase substrates. Overall, our data show that hDJ-1 contains intrinsic redox-sensitive esterase activity that is abolished in a PD-associated mutant form of the hDJ-1 protein. 相似文献
65.
66.
Dario Cavallo Lorenza Gardella Giuseppe Portale Alejandro J. Müller Giovanni C. Alfonso 《Polymer》2014
Isotactic poly(1-butene) (i-PBu) is a polyolefin of industrial relevance which exhibits an interesting polymorphism. Upon cooling from the relaxed melt at atmospheric pressure, a tetragonal phase (Form II) develops. However, being metastable, this structure slowly evolves upon aging in the stable trigonal modification (Form I). Another trigonal modification, denoted Form I′, can also crystallize directly from the melt if proper conditions are met, e.g., high pressure, low tacticity, ultrathin samples etc. In this work, we aim to verify whether, by acting on the nucleation stage via a proper thermal history, the direct formation of the trigonal polymorph from the melt in a bulk sample is possible. Nucleation of i-PBu has been tailored by means of the self-nucleation technique, imposed on previously aged samples (Form I). DSC and temperature-resolved WAXS show that different crystallization pathways can be observed, depending on the residual concentration of Form I self-nuclei. With decreasing self-nucleation temperature we first encounter “cross-nucleation” of the tetragonal crystal on trigonal nuclei, followed by concomitant crystallization of Form II and Form I′ and eventually the sole formation of the trigonal modification (Form I′). 相似文献
67.
68.
69.
Alejandro Aparicio-Saguilán Andrés Aguirre-Cruz Guadalupe Méndez-Montealvo Sandra L. Rodriguez-Ambriz Francisco J. Garcia-Suarez Delia E. Páramo-Calderón Luis A. Bello-Pérez 《LWT》2014
Two banana starches were studied to analyze the effect of the acid hydrolysis on their molecular structure, and the impact in their physicochemical features. The native banana starches exhibit differences in the amylose content, molar mass, gelatinization parameters, X-ray diffraction pattern, and pasting profile. These results suggested that different acid hydrolysis mechanisms may be operative in these two starches. The kinetic hydrolysis is different in both banana starches that are related to the crystalline packing of the starch molecules. This was confirmed by the amylose content, the X-ray diffraction pattern, and the thermal study in the acid hydrolyzed starches at different times. The acid-treated Roatan starch showed higher retrogradation than Macho starch, a phenomenon that increases in the sample hydrolyzed for the longer time. This pattern is related to the amylose/amylopectin ratio, the reduction in the molar mass and the gyration radius. The acid hydrolysis of banana starches, although they have some similarities, they are different. 相似文献
70.
Crespo JF Retzek M Foetisch K Sierra-Maestro E Cid-Sanchez AB Pascual CY Conti A Feliu A Rodriguez J Vieths S Scheurer S 《Molecular nutrition & food research》2006,50(3):282-290
Oranges are clinically relevant allergenic foods. To date, orange allergens have not been characterized in detail. The study is aimed at analyzing the sensitization profile in orange-sensitized subjects with and without clinical allergy, and to identify orange allergens. Fifty-six sensitized subjects with self-reported reactions to orange were grouped into reactors (anaphylaxis or multiple episodes of immediate reactions and/or positive challenge tests) and non-reactors (negative open food challenge tests). Allergens were characterized by IgE immunoblotting, N-terminal sequencing, IgE-inhibition assays, and mediator release assays were performed to determine the allergenic potency of orange profilin. Of 56 subjects, 23 were classified as orange allergic showing mainly an oral allergy syndrome. Of 23 subjects classified as orange allergic, 22 were sensitized to profilin, Cit s 2. In patients with mono-sensitization to profilin in vitro histamine releases up to 75% from basophils were induced using orange extract and purified plant profilins. Of the allergic patients 78% were sensitized to germin-like protein, Cit s 1. Both allergens showed retained IgE reactivity in heat-processed orange juice. Interestingly, subjects with and without clinical allergy showed a comparable sensitization profile. Profilin and germin-like proteins are major orange allergens. The potential clinical relevance of orange profilin was indicated by its strong capacity to release histamine from basophils. However, a predominant sensitization to both allergens in subjects without symptoms also indicates a high frequency of clinically insignificant sensitization. 相似文献