全文获取类型
收费全文 | 447篇 |
免费 | 20篇 |
专业分类
电工技术 | 4篇 |
综合类 | 3篇 |
化学工业 | 110篇 |
金属工艺 | 2篇 |
机械仪表 | 4篇 |
建筑科学 | 22篇 |
矿业工程 | 3篇 |
能源动力 | 6篇 |
轻工业 | 77篇 |
水利工程 | 8篇 |
无线电 | 12篇 |
一般工业技术 | 61篇 |
冶金工业 | 115篇 |
自动化技术 | 40篇 |
出版年
2023年 | 1篇 |
2022年 | 9篇 |
2021年 | 25篇 |
2020年 | 7篇 |
2019年 | 11篇 |
2018年 | 11篇 |
2017年 | 14篇 |
2016年 | 7篇 |
2015年 | 16篇 |
2014年 | 4篇 |
2013年 | 27篇 |
2012年 | 21篇 |
2011年 | 35篇 |
2010年 | 24篇 |
2009年 | 21篇 |
2008年 | 42篇 |
2007年 | 32篇 |
2006年 | 23篇 |
2005年 | 16篇 |
2004年 | 10篇 |
2003年 | 15篇 |
2002年 | 14篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 12篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 5篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 5篇 |
1990年 | 3篇 |
1989年 | 3篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有467条查询结果,搜索用时 15 毫秒
121.
Heidi Böhm Alexander Emelianov Alexander Eremin Christof Schulz Helga Jander 《Combustion and Flame》2012,159(3):932-939
The effect of H2 and C2H2 addition on particle formation in the pyrolysis of C3O2/Ar mixtures was studied behind reflected shock waves. An existing reaction mechanism for the pyrolysis of highly-diluted C3O2 in argon was expanded to conditions with higher C3O2 concentrations (up to 33 volume%) at elevated pressures and high temperatures and was validated against experimental data. The simulations for the gas-phase chemistry were performed with the program CHEMKIN. The heterogeneous particle formation was modeled by post-processing using the program PREDICI relying on the Galerkin method. It was found that in C3O2/H2/Ar pyrolysis, the induction times and rate constants of particle formation do not differ significantly from those of pure C3O2/Ar pyrolysis. However, the presence of H2 reduced the particle volume fraction, the mean diameter of particles, the particle number density, and the maximum temperature rise of the mixture. Hydrocarbon-bonded hydrogen in C3O2/C2H2/Ar pyrolysis caused significantly increased induction times for particle formation, decreased particle volume fractions, and decreased temperature rises. The different reaction channels for carbon particle formation were identified in view of the role of hydrogen. An alternating reaction channel including C2 species played an important role in forming polycyclic aromatic hydrocarbons (PAH) in the mixtures. 相似文献
122.
Susan M. Fluegel Terry D. Shultz Joseph R. Powers Stephanie Clark Celestina Barbosa-Leiker Bruce R. Wright Timothy S. Freson Heidi A. Fluegel Jonathan D. Minch Lance K. Schwarzkopf Ashley J. Miller Michael M. Di Filippo 《International Dairy Journal》2010,20(11):753-760
Whey protein beverages reduced blood pressure in young men and women in a six week controlled intervention. There were no differences in systolic blood pressure (SBP), diastolic blood pressure (DBP), or mean arterial pressure (MAP) observed between groups consuming 28 g per day of either hydrolyzed or non-hydrolyzed whey protein in a beverage. However, in young adults with elevated DBP and SBP, whey beverage consumption significantly decreased SBP, DBP, and MAP by 8.0, 8.6, and 6.4 mm Hg, respectively (P ≤ 0.001 for all comparisons). In subjects with elevated SBP only, SBP significantly decreased by 3.8 mm Hg (P ≤ 0.04) after the whey beverage intervention. Subjects with normal blood pressure had no change in SBP, DBP, and MAP. Whey beverages also significantly decreased total and low-density lipoprotein cholesterol concentrations (P ≤ 0.001 and 0.05, respectively). Whey protein beverages may be useful for the dietary treatment of prehypertension and/or stage 1 hypertension. 相似文献
123.
Heidi A. Campbell 《Journal of Computer-Mediated Communication》2010,15(2):251-276
It is often argued that the internet poses a threat to traditional forms of authority. Within studies of religion online claims have also been made that the internet is affecting religious authority online, but little substantive work has backed up these claims. This paper argues for an approach to authority within online studies which looks separately at authority: roles, structures, beliefs/ideologies and texts. This approach is applied to a thematic analysis of 100 religious blogs and demonstrates that religious bloggers use their blogs to frame authority in ways that may more often affirm than challenge traditional sources of authority. 相似文献
124.
Ville Könönen Jani Mäntyjärvi Heidi Similä Juha Pärkkä Miikka Ermes 《Pervasive and Mobile Computing》2010,6(2):181-197
In mobile devices there exist several in-built sensor units and sources which provide data for context reasoning. More context sources can be attached via wireless network connections. Usually, the mobile devices and the context sources are battery powered and their computational and space resources are limited. This sets special requirements for the context recognition algorithms. In this paper, several classification and automatic feature selection algorithms are compared in the context recognition domain. The main goal of this study is to investigate how much advantage can be achieved by using sophisticated and complex classification methods compared with a simple method that can easily be implemented in mobile devices. The main result is that even a simple linear classification algorithm can achieve a reasonably good accuracy if the features calculated from raw data are selected in a suitable way. Usually context recognition algorithms are fitted to a particular problem instance in an off-line manner and modifying methods for on-line learning is difficult or impossible. An on-line version of the Minimum-distance classifier is presented in this paper and it is justified that it leads to considerably higher classification accuracies compared with the static off-line version of the algorithm. Moreover, we report superior performance for the Minimum-distance classifier compared to other classifiers from the view point of computational load and power consumption of a smart phone. 相似文献
125.
Marcel Mertz M.A. Dr. Heidi Albisser Schleger Dr. med. Barbara Meyer-Zehnder Prof. Dr. Stella Reiter-Theil 《Ethik in der Medizin》2014,26(2):91-104
Definition of the Problem Models of decision making in medical ethics have to establish themselves as being able to lead to ethically right or at least “credible” decisions. For this purpose, approaches of theoretical justification stemming from ethics are vital. However, clinical ethics is sometimes criticized for theoretical deficits. In order to address this criticism, we will try to justify ethical case discussion and ethics consultation by principlism and discourse ethics by referring to a clinical ethics project (METAP). Arguments Principlism and discourse ethics can fruitfully complement each other when used in ethical case discussion or consultation. Thereby, some theoretical as well as practical weaknesses of both approaches can be mitigated. Discourse ethics, for example, safeguards the ethical validity of moral decisions and norms for action, respectively, thus mitigating shortcomings of justification when using principlism. Conversely, principlism answers questions concerning ethical adequacy and functions particularly as a safeguard for appropriate decisions in the individual case. Conclusion By using a combination of these two approaches, a broader justification seems possible rather than by relying on principlism or discourse ethics alone. Even if some challenges persist, and even if the combined model cannot always prevent dissent, it may strengthen practical confidence in the ethical decision by its ?double“ safeguards (principles and discourse). This could render clinical ethics more ?robust“ that have been missing so far. 相似文献
126.
One‐ and two‐dimensional diffraction gratings were fabricated on commercial polyethylene terephthalate (PET) film by two beam direct laser interference patterning (DLIP) method using a pulse laser (10 ns) with a wavelength of 266 nm. The relative diffraction efficiency of the structured specimens (at 633 nm) in transmission mode was measured and correlated with the topological characteristics of the structured PET substrates. The obtained diffraction gratings made by DLIP show better or similar diffraction efficiencies when compared with the reported efficiency of gratings made by other methods (up to 42.5% for 1 μm arrays), and can be fabricated on large areas in very short processing times (up to 18 cm2/s). POLYM. ENG. SCI., 52:1903–1908, 2012. © 2012 Society of Plastics Engineers 相似文献
127.
Heidi M. Appel Heather L. Govenor Mark D'Ascenzo Erin Siska Jack C. Schultz 《Journal of chemical ecology》2001,27(4):761-778
We examined the response of the widely used Folin-Denis assay to purified tannins from 16 woody plant species and to three commercial polyphenol preparations often used as standards. The reagent's response to these chemical mixtures differed significantly among sources (tree species, commercial preparations) and sampling dates, even though the mixtures contained the same total dry weight of tannins. Response to commercial standards usually did not resemble response to actual plant tannin and produced estimates that differed from actual concentrations by as much as twofold. Species-based and seasonal differences in polyphenol composition are evidently responsible for these variable results. Reagents that depend on redox reactions, such as the Folin-Denis, do not produce reliable absolute or relative quantification of phenolics when different species or samples from different dates are compared, and use of commercial standards does not resolve this problem. 相似文献
128.
A Abudukadeer R Bakry G Goebel I Mutz-Dehbalaie A Widschwendter GK Bonn H Fiegl 《International journal of molecular sciences》2012,13(7):8353-8363
This study was designed to investigate the DNA-methylation status of E-cadherin (CDH1) and H-cadherin (CDH13) in serum samples of cervical cancer patients and control patients with no malignant diseases and to evaluate the clinical utility of these markers. DNA-methylation status of CDH1 and CDH13 was analyzed by means of MethyLight-technology in serum samples from 49 cervical cancer patients and 40 patients with diseases other than cancer. To compare this methylation analysis with another technique, we analyzed the samples with a denaturing high performance liquid chromatography (DHPLC) PCR-method. The specificity and sensitivity of CDH1 DNA-methylation measured by MethyLight was 75% and 55%, and for CDH13 DNA-methylation 95% and 10%. We identified a specificity of 92.5% and a sensitivity of only 27% for the CDH1 DHPLC-PCR analysis. Multivariate analysis showed that serum CDH1 methylation-positive patients had a 7.8-fold risk for death (95% CI: 2.2-27.7; p = 0.001) and a 92.8-fold risk for relapse (95% CI: 3.9-2207.1; p = 0.005). We concluded that the serological detection of CDH1 and CDH13 DNA-hypermethylation is not an ideal diagnostic tool due to low diagnostic specificity and sensitivity. However, it was validated that CDH1 methylation analysis in serum samples may be of potential use as a prognostic marker for cervical cancer patients. 相似文献
129.
Heidi Peltola Kirsi Immonen Leena-Sisko Johansson Jussi Virkajärvi David Sandquist 《应用聚合物科学杂志》2019,136(37):47955
This article focuses on the effect of pulp bleaching and emerging commercial compatibilizers on physical performance of pulp fiber reinforced poly(lactic acid) (PLA) biocomposites. Industrially bleached and unbleached hardwood kraft pulp fibers are treated with several additive types, and compounded with PLA to fiber content of 30 wt %. After injection molding, the produced biocomposites are evaluated by their mechanical performance and fiber–matrix adhesion. For selected materials, fiber surface and fiber properties are reflected to composite performance by analyzing the compositions, dimensions, and lignin coverage of original fibers, as well as fiber dispersion and dimensions after melt processing. As a conclusion, unbleached kraft pulp fibers provide significant improvement in physical properties of PLA/pulp fiber composites. Of the screened compatibilizers, epoxidated linseed oil has a clear positive effect on performance when bleached kraft pulp fibers are used. The improvements correspond to enhanced fiber–matrix adhesion and differences in remaining fiber length distributions. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47955. 相似文献
130.
Satu Ojala Ulla Lassi Reeta Ylnen Heidi Karjalainen Riitta Liisa Keiski 《Catalysis Today》2005,100(3-4):367-372
In industrial scale catalytic volatile organic compounds (VOCs) incineration it is sometimes observed that the VOC conversions are higher than expected, based on the laboratory scale experiments at the same temperatures. One reason for this is that the construction material of the industrial scale catalytic incinerator may have an effect on the total VOC conversion. In this study, the effect of construction material on VOC removal activity is studied through laboratory experiments, by thermodynamic calculations and by flow modelling. The results showed that copper and Aluzinc decreased the light-off temperature (T50) of n-butyl acetate compared to thermal experiments. Copper and Aluzinc did not, however, further decrease the T50 when they were introduced into the reactor packed with the catalyst. The higher total VOC conversion observed in the industrial scale incinerator is presumably due to the higher temperatures at the outlet of the catalyst, which is maintained by the heat exchangers. 相似文献