全文获取类型
收费全文 | 3520篇 |
免费 | 228篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 47篇 |
综合类 | 3篇 |
化学工业 | 1141篇 |
金属工艺 | 44篇 |
机械仪表 | 78篇 |
建筑科学 | 125篇 |
矿业工程 | 3篇 |
能源动力 | 118篇 |
轻工业 | 400篇 |
水利工程 | 18篇 |
无线电 | 320篇 |
一般工业技术 | 644篇 |
冶金工业 | 110篇 |
原子能技术 | 43篇 |
自动化技术 | 657篇 |
出版年
2024年 | 8篇 |
2023年 | 44篇 |
2022年 | 243篇 |
2021年 | 268篇 |
2020年 | 112篇 |
2019年 | 103篇 |
2018年 | 128篇 |
2017年 | 127篇 |
2016年 | 161篇 |
2015年 | 142篇 |
2014年 | 149篇 |
2013年 | 235篇 |
2012年 | 220篇 |
2011年 | 273篇 |
2010年 | 195篇 |
2009年 | 195篇 |
2008年 | 168篇 |
2007年 | 144篇 |
2006年 | 140篇 |
2005年 | 100篇 |
2004年 | 88篇 |
2003年 | 70篇 |
2002年 | 53篇 |
2001年 | 38篇 |
2000年 | 29篇 |
1999年 | 37篇 |
1998年 | 37篇 |
1997年 | 35篇 |
1996年 | 30篇 |
1995年 | 13篇 |
1994年 | 25篇 |
1993年 | 11篇 |
1992年 | 10篇 |
1991年 | 5篇 |
1989年 | 8篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 6篇 |
1985年 | 12篇 |
1984年 | 8篇 |
1983年 | 17篇 |
1982年 | 8篇 |
1981年 | 9篇 |
1980年 | 12篇 |
1979年 | 7篇 |
1978年 | 3篇 |
1977年 | 9篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有3751条查询结果,搜索用时 0 毫秒
161.
Reduced percolation concentration in polypropylene/expanded graphite composites: Effect of viscosity and polypyrrole 下载免费PDF全文
Jürgen Pionteck Elixana Maria Melchor Valdez Francesco Piana Mária Omastová Adriaan Stephanus Luyt Brigitte Voit 《应用聚合物科学杂志》2015,132(20)
With the goal to obtain material combining electrical and thermal conductivity at low filler loadings, composites based on polypropylenes (PP) and expanded graphite (EG) have been prepared. The effects of matrix viscosity and of coating the EG particles with polypyrrole (PPy, EG/PPy = 37.5/62.5 by weight) on the EG dispersibility and formation of percolation structures have been analyzed. When increasing the EG amount from 6 to 8 wt %, the electrical conductivity of PP/EG composites increased by 7–9 orders of magnitude, independent of matrix viscosity. When EG‐PPy is added, percolation was observed between 8 and 12 wt % EG‐PPy (3 and 4.5 wt % EG) in case of PP with higher viscosity and 6 wt % EG (2.25 wt % EG) in case of PP with lower viscosity, exhibiting a strong synergistic effect of EG and PPy in the latter case. In contrast, PPy does not contribute to reduction of thermal percolation concentration. Thermal percolation is observed at 8 wt % EG in PP/EG composites, but no percolation was found in PP/EG‐PPy composites with EG‐PPy contents of up to 20 wt %, corresponding to 7.5 wt % EG. Analyzing the melt rheology it becomes clear that the contribution of PPy to the formation of a filler network is strongly dependent on the matrix viscosity. The comparison of thermal, electrical and rheological percolation reveals that PPy participates in electron transport reducing the electrical percolation but not to heat transport. Overall, we found a good correlation between electrical, thermal, and melt rheological percolation concentrations. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41994. 相似文献
162.
163.
164.
165.
Irene Vanni Simona Coco Anna Truini Marta Rusmini Maria Giovanna Dal Bello Angela Alama Barbara Banelli Marco Mora Erika Rijavec Giulia Barletta Carlo Genova Federica Biello Claudia Maggioni Francesco Grossi 《International journal of molecular sciences》2015,16(12):28765-28782
Next-generation sequencing (NGS) is a cost-effective technology capable of screening several genes simultaneously; however, its application in a clinical context requires an established workflow to acquire reliable sequencing results. Here, we report an optimized NGS workflow analyzing 22 lung cancer-related genes to sequence critical samples such as DNA from formalin-fixed paraffin-embedded (FFPE) blocks and circulating free DNA (cfDNA). Snap frozen and matched FFPE gDNA from 12 non-small cell lung cancer (NSCLC) patients, whose gDNA fragmentation status was previously evaluated using a multiplex PCR-based quality control, were successfully sequenced with Ion Torrent PGM™. The robust bioinformatic pipeline allowed us to correctly call both Single Nucleotide Variants (SNVs) and indels with a detection limit of 5%, achieving 100% specificity and 96% sensitivity. This workflow was also validated in 13 FFPE NSCLC biopsies. Furthermore, a specific protocol for low input gDNA capable of producing good sequencing data with high coverage, high uniformity, and a low error rate was also optimized. In conclusion, we demonstrate the feasibility of obtaining gDNA from FFPE samples suitable for NGS by performing appropriate quality controls. The optimized workflow, capable of screening low input gDNA, highlights NGS as a potential tool in the detection, disease monitoring, and treatment of NSCLC. 相似文献
166.
Hazi Ahmad Beejapur Vincenzo Campisciano Francesco Giacalone Michelangelo Gruttadauria 《Advanced Synthesis \u0026amp; Catalysis》2015,357(1):51-58
A novel fullerene [5:1]hexakisadduct bearing two 2,2,6,6‐tetramethylpiperidine 1‐oxyl (TEMPO) radicals and ten 1‐propyl‐3‐methylimidazolium bromide moieties has been synthesized and characterized. Such an C60IL10TEMPO2 hybrid has been successfully employed as a catalyst in the selective oxidation of a wide series of alcohols and is highly active at just 0.1 mol% loading. Moreover, it can be easily recovered by adsorption onto a multi‐layered covalently‐linked SILP phase (mlc‐SILP) through a “release and catch” approach and reused for up to 12 cycles without loss in efficiency. Interestingly, a catalytic synergistic effect of TEMPO and imidazolium bromide moieties combined in the same hybrid has been clearly shown.
167.
Traditional Mediterranean diets, as opposed to North European and American diets, include a significantly large amount of plant foods; this notable difference between the two eating styles, despite the similarities among other classic risk factors for coronary heart disease (CHD) such as high plasma cholesterol levels, has been associated with a lower risk of developing the CHD and certain cancers. The involvement of excessive free radical production and the great number of epidemiologic studies linking antioxidant intake with a reduced incidence of the above-mentioned diseases indicate that dietary antioxidants likely play a protective role. Because diets in the Mediterranean are (or better yet, were) characterized by abundant plant foods (fruits, vegetables, breads, nuts, seeds; wine and olive oil), this article includes a review of the potential activities of dietary antioxidants, which are plentiful in Mediterranean diets, and wine as related to human disease. 相似文献
168.
Vladimir A. Tyurin Gianfranca Carta Yulia Y. Tyurina Sebastiano Banni Billy W. Day Francesco P. Corongiu Valerian E. Kagan 《Lipids》1997,32(2):131-142
Recent studies provide extensive evidence for the importance of carotenoids in protecting against oxidative stress associated
with a number of diseases. In particular, reactions of carotenoids with phenoxyl radicals generated by peroxidasecatalyzed
one-electron metabolism of phenolic compounds may represent an important antioxidant function of carotenoids. To further our
understanding of the antioxidant mechanisms of carotenoids, we used in the present work two different phenolic compounds,
phenol and a polar homologue of vitamin E (2,2,5,7,8-pentamethyl-6-hydroxychromane, PMC), as representatives of two different
types of phenols to study reactions of their respective phenoxyl radicals with carotenoids in cells and in model systems.
We found that phenoxyl radicals of PMC did not oxidize β-carotene in either HL-60 cells or in model systems with horseradish
peroxidase (HRP)/H2O2. In contrast, the phenoxyl radicals generated from phenol (by native myeloperoxidase in HL-60 cells or HRP/H2O2 in model systems) effectively oxidized β-carotene and other carotenoids (canthaxanthin, lutein, lycopene). One-electron reduction
of the phenoxyl radical by ascorbate (assayed by electron spin resonance-detectable formation of semidehydroascorbyl radicals)
prevented HRP/H2O2-induced oxidation of β-carotene. PMC, but not phenol, protected β-carotene against oxidation induced by a lipid-soluble azo-initiator
of peroxyl radicals. No adducts of peroxidase/phenol/H2O2-induced β-carotene oxidation intermediates with phenol were detected by high-performance liquid chromatography-mass spectrometry
analysis of the reaction mixture. Since carotenoids are essential constituents of the antioxidant defenses in cells and biological
fluids, their depletion through the reaction with phenoxyl radicals formed from endogenous, nutritional and environmental
phenolics, as well as phenolic drugs, may be an important factor in the development of oxidative stress. 相似文献
169.
Natural compounds and vegetable powders improve the stability and antioxidant properties of Brassica napus L. var. oleifera (rapeseed) oil 下载免费PDF全文
170.
A New Formulation Based on Ozonated Sunflower Seed Oil: In Vitro Antibacterial and Safety Evaluation
Francesca Serio Graziano Pizzolante Giuseppe Cozzolino Maria D’Alba Francesco Bagordo Mattia De Giorgi 《臭氧:科学与工程》2017,39(3):139-147
The objective of this study was to investigate the potential in vitro biological properties of Oz.Or.Oil 30, a new formulation composed of 30% ozonated sunflower seed oil, which is believed to keep skin smooth and moisturized, supporting repair processes, tissue regeneration and re-epithelialization of wounds. The antibacterial activity, the qualitative and quantitative evaluation of the cytotoxic effect of the formulation on cultures of Vero cells and 3T3 fibroblasts showed that Oz.Or.Oil 30 merits further in vivo study using clinical-laboratory correlations, because it could be suggested as an alternative therapy against bacterial and fungal diseases. 相似文献