全文获取类型
收费全文 | 2100篇 |
免费 | 182篇 |
专业分类
电工技术 | 24篇 |
综合类 | 1篇 |
化学工业 | 508篇 |
金属工艺 | 45篇 |
机械仪表 | 22篇 |
建筑科学 | 91篇 |
矿业工程 | 8篇 |
能源动力 | 41篇 |
轻工业 | 190篇 |
水利工程 | 20篇 |
石油天然气 | 1篇 |
无线电 | 220篇 |
一般工业技术 | 500篇 |
冶金工业 | 214篇 |
原子能技术 | 4篇 |
自动化技术 | 393篇 |
出版年
2023年 | 12篇 |
2022年 | 11篇 |
2021年 | 30篇 |
2020年 | 38篇 |
2019年 | 27篇 |
2018年 | 90篇 |
2017年 | 86篇 |
2016年 | 113篇 |
2015年 | 75篇 |
2014年 | 92篇 |
2013年 | 173篇 |
2012年 | 124篇 |
2011年 | 151篇 |
2010年 | 116篇 |
2009年 | 110篇 |
2008年 | 113篇 |
2007年 | 110篇 |
2006年 | 86篇 |
2005年 | 80篇 |
2004年 | 71篇 |
2003年 | 59篇 |
2002年 | 65篇 |
2001年 | 16篇 |
2000年 | 31篇 |
1999年 | 19篇 |
1998年 | 43篇 |
1997年 | 37篇 |
1996年 | 35篇 |
1995年 | 21篇 |
1994年 | 23篇 |
1993年 | 24篇 |
1992年 | 17篇 |
1991年 | 14篇 |
1990年 | 11篇 |
1989年 | 7篇 |
1988年 | 11篇 |
1987年 | 7篇 |
1986年 | 8篇 |
1985年 | 18篇 |
1983年 | 7篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 11篇 |
1978年 | 7篇 |
1977年 | 5篇 |
1976年 | 6篇 |
1974年 | 6篇 |
1960年 | 6篇 |
1959年 | 4篇 |
排序方式: 共有2282条查询结果,搜索用时 156 毫秒
101.
102.
Moïse Nola Mireille E. Nougang Olive V. Noah Ewoti Luciane M. Moungang François Krier Nour‐Eddine Chihib 《Water and Environment Journal》2013,27(3):328-337
This study was aimed at assessing the prevalence of pathogenic Escherichia coli strains, relative to the total count of E. coli, faecal coliforms and other heterotrophic mesophilic aerobic bacteria (HMAB) isolated in groundwater in the equatorial region of Cameroon (Central Africa). Bacteria were isolated using standard methods. Pathogenic E. coli strains were then identified using haemagglutination and antisera tests. The maximum abundance of HMAB, faecal coliforms and E. coli strains were 4.9 × 106, 5.6 × 103 and 1 × 103 colony‐forming units (CFU)/100 mL, respectively. The count of pathogenic E. coli strains reached 3 CFU/100 mL. The counts of commensal and pathogenic E. coli strains underwent temporal and spatial fluctuations. In 21% of sampling sites, the abundance of faecal coliforms was significantly correlated to that of E. coli (P < 0.05). However, the isolated bacterial count was not significantly correlated to that of the pathogenic E. coli strains (P > 0.05). The bacteria abundance dynamics may be impacted by many interacting factors. 相似文献
103.
Within Australian cities, social and economic inequalities manifest themselves spatially. Perceived neighbourhood disorder and neighbourhood reputation are relevant to considering the ways in which social and economic inequalities translate into place-based inequalities. This article explores the ways in which residents of two socio-economically contrasting urban areas describe and explain neighbourhood disorder and neighbourhood reputation. It draws upon qualitative data from 40 in-depth interviews, in addition to quantitative data from a postal survey. The qualitative findings highlighted how issues of neighbourhood disorder and reputation were intertwined. In both areas, participants sought to portray themselves and their neighbourhoods in positive ways, by attributing responsibility for neighbourhood disorder to people who were unlike themselves, and by highlighting places that were perceived to have worse reputations and higher levels of disorder. The findings are considered in light of Bourdieu's theory of capitals. This article indicates that both neighbourhood disorder and reputation are pathways through which social, economic and health inequities are maintained in urban areas. 相似文献
104.
BaTiO3 incorporation effect on the dielectric properties of polymer from aqueous emulsion: An enhanced dispersion technique
下载免费PDF全文
![点击此处可从《应用聚合物科学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
An economic and environment friendly process was adapted to synthesize new dielectric composite materials. Using ethylene vinyl acetate (EVA)/vinyl ester of versatic acid (VeoVa) terpolymer as an aqueous emulsion provides a homogenous dispersion of BaTiO3 (BT) particles, due to the high viscosity and polarity of the vinyl resin (VR). Composites films were obtained from these dispersions by water evaporation. The evolution of the dielectric properties as a function of the BaTiO3 content, was correctly fitted by a Maxwell‐Garnett model. This fitting of the experimental curve shows a good dispersion of filler in the vinyl resin and the particles separation by a layer of resin as expected for the preparation method used in this study. The VR/BT composites show good synergy between the dielectric properties of the different phases of the composites due to the formation of macrodipoles and to the strong interactions between polar EVA/VeoVa groups and the BaTiO3 particles surface. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44333. 相似文献
105.
Structure–Activity Relationships of JMV4463, a Vectorized Cathepsin D Inhibitor with Antiproliferative Properties: The Unique Role of the AMPA‐Based Vector
下载免费PDF全文
![点击此处可从《ChemMedChem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Lubomir L. Vezenkov Clément A. Sanchez Dr. Virginie Bellet Dr. Vincent Martin Dr. Marie Maynadier Dr. Nadir Bettache Prof. Vincent Lisowski Prof. Jean Martinez Dr. Marcel Garcia Dr. Muriel Amblard Dr. Jean‐François Hernandez 《ChemMedChem》2016,11(3):302-308
Cathepsin D (CathD) is overexpressed and secreted by several solid tumors and stimulates their growth, the mechanism of which is still not understood. In this context, the pepstatin bioconjugate JMV4463 [Ac‐arg‐O2Oc‐(Val)3‐Sta‐Ala‐Sta‐(AMPA)4‐NH2; O2Oc=8‐amino‐3,6‐dioxaoctanoyl, Sta=statine, AMPA=ortho‐aminomethylphenylacetyl], containing a new kind of cell‐penetrating vector, was previously shown to exhibit potent antiproliferative effects in vitro and to delay the onset of tumors in vivo. In this study, we performed a structure–activity relationship analysis to evaluate the significance of the inhibitor and vector moieties of JMV4463. By modifying both statine residues of pepstatin we found that the antiproliferative activity is correlated with CathD inhibition, supporting a major role of the catalytic activity of intracellular CathD in cancer cell proliferation. Replacing the vector composed of four AMPA units with other vectors was found to abolish cytotoxicity, although all of the conjugates enabled pepstatin transport into cells. In addition, the AMPA4 vector must be localized at the C terminus of the bioconjugate. The unexpected importance of the vector structure and position for cytotoxic action suggests that AMPA4 enables pepstatin to inhibit the proteolysis of critical CathD substrates involved in cell proliferation via a unique mechanism of action. 相似文献
106.
Discovery of Highly Potent Dual Orexin Receptor Antagonists via a Scaffold‐Hopping Approach
下载免费PDF全文
![点击此处可从《ChemMedChem》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Dr. Bibia Heidmann Dr. John Gatfield Dr. Catherine Roch Dr. Alexander Treiber Dr. Simone Tortoioli Dr. Christine Brotschi Dr. Jodi T. Williams Dr. Martin H. Bolli Dr. Stefan Abele Dr. Thierry Sifferlen Dr. François Jenck Dr. Christoph Boss 《ChemMedChem》2016,11(19):2132-2146
Starting from suvorexant (trade name Belsomra), we successfully identified interesting templates leading to potent dual orexin receptor antagonists (DORAs) via a scaffold‐hopping approach. Structure–activity relationship optimization allowed us not only to improve the antagonistic potency on both orexin 1 and orexin 2 receptors (Ox1 and Ox2, respectively), but also to increase metabolic stability in human liver microsomes (HLM), decrease time‐dependent inhibition of cytochrome P450 (CYP) 3A4, and decrease P‐glycoprotein (Pgp)‐mediated efflux. Compound 80 c [{(1S,6R)‐3‐(6,7‐difluoroquinoxalin‐2‐yl)‐3,8‐diazabicyclo[4.2.0]octan‐8‐yl}(4‐methyl‐[1,1′‐biphenyl]‐2‐yl)methanone] is a potent and selective DORA that inhibits the stimulating effects of orexin peptides OXA and OXB at both Ox1 and Ox2. In calcium‐release assays, 80 c was found to exhibit an insurmountable antagonistic profile at both Ox1 and Ox2, while displaying a sleep‐promoting effect in rat and dog models, similar to that of the benchmark compound suvorexant. 相似文献
107.
The objective of this study is to develop a new biocomposite material with high deformation ability. In this regard, the thermal, rheological, and thermophysical properties of this new composite were characterized as a function of temperature and filler concentration. High density polyethylene (HDPE) was the matrix of this new composite which was reinforced with six sawdust concentrations 0%, 20%, 30%, 40%, 50%, and 60%. Maleic anhydride grafted polyethylene (PE‐g‐MA) was used as coupling agent. Addition of sawdust with PE‐g‐MA increased significantly the complex viscosity, the storage modulus (G′), and loss modulus (G″) of the matrix. The superposition of the complex viscosity curves using temperature dependent shift factor, allowed the construction of a viscosity master curve covering a wide range of temperatures. Arrhenius law was used for the relationship of the shift factor to temperature. Furthermore, method of Van Gurp and Palmen (tan delta vs. G*) is also used to control the time–temperature superposition. The experimental results can be well fitted with the cross rheological model which allowed the prediction of the thermorheological properties of the composites over a broad frequency range. By increasing wood concentration, both the activation energy and relaxation time for the biocomposites determined using, respectively, the Arrhenius law and the cole–cole rule increased. By contrast, specific heat of the matrix decreased with sawdust addition while its dimensional stability improved. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40495. 相似文献
108.
Densification of 8Y‐Tetragonal‐Stabilized Zirconia Optoceramics with Improved Optical Properties by Y Segregation
下载免费PDF全文
![点击此处可从《International Journal of Applied Ceramic Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Mythili Prakasam François Weill Eric Lebraud Oudomsack Viraphong Sonia Buffiére Alain Largeteau 《International Journal of Applied Ceramic Technology》2016,13(5):904-911
8% Yttria‐stabilized zironcia (8YSZ) transparent ceramics have a wide technological applications. Segregation of the Y around the grain boundaries is favored by slow heating rate. The optimized sintering parameters helped in obtaining transparent ceramics of 8YSZ with a high percentage of cubic phase in addition to the presence of tetragonal phase. HRTEM was used to verify the grain growth suppression and to observe the presence of the cubic phase. The presence of cubic phase has suppressed the grain growth, which increased the transparency in the visible and infrared region without the addition of dopants or by utilizing high pressure. 相似文献
109.
François Mancebo 《Journal of Urbanism》2020,13(2):133-152
ABSTRACTA city is not only made of buildings and infrastructures, but is also composed of the people, who live there, their cultures, uses and interactions. How people’s relations to their place have been transformed or not by the configuration of the smart city? This article attempts to provide an answer to this question, by examining the case of Amsterdam, Barcelona, and Paris, three large centuries-old Western Europe cities. It shows that behind the official line promising a more participatory society, the inhabitants are rather turned into users or clients of a city that belongs no more to them. Courses of action are then elaborated to help reurbanize the smart city by fostering co-construction of smart strategies. 相似文献
110.
Christine Feillet-Coudray Gilles Fouret Claire Vigor Béatrice Bonafos Bernard Jover Agnieszka Blachnio-Zabielska Jennifer Rieusset François Casas Sylvie Gaillet Jean Francois Landrier Thierry Durand Charles Coudray 《Lipids》2019,54(1):81-97
Inflammation and oxidative stress are thought to be involved in, or associated with, the development of obesity, dyslipidemia, hepatic steatosis, and insulin resistance. This work was designed to determine the evolution of inflammation and oxidative stress during onset and progression of hepatic steatosis and glucose intolerance. Seventy-five male Wistar rats were divided to control and high-fat high-fructose (HFHFr) groups. A subgroup of each group was sacrificed at 4, 8, 12, 16, and 20 weeks. HFHFr-fed rats exhibited overweight, glucose intolerance, and hepatic steatosis with increased contents of hepatic diacylglycerols and ceramides. The HFHFr diet increased hepatic interleukin 6 (IL-6) protein and adipose tissue CCL5 gene expression and hepatic nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity but not mitochondrial reactive oxygen species (ROS) production. The HFHFr diet decreased plasma and liver levels of isoprostanoid metabolites as well as plasma thiobarbituric acid-reactive substance (TBARS) levels. Hepatic glutathione content was decreased with a moderate decrease in superoxide dismutase (SOD) and glutathione peroxidase (GPx) with the HFHFr diet. Overall, HFHFr diet led to hepatic lipid accumulation and glucose intolerance, which were accompanied by only moderate inflammation and oxidative stress. Most of these changes occurred at the same time and as early as 8 or 12 weeks of diet treatment. This implies that oxidative stress may be the result, not the cause, of these metabolic alterations, and suggests that marked hepatic oxidative stress should probably occur at the end of the steatotic stage to result in frank insulin resistance and steatohepatitis. These findings need to be further evaluated in other animal species as well as in human studies. 相似文献