全文获取类型
收费全文 | 501篇 |
免费 | 10篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 160篇 |
金属工艺 | 17篇 |
机械仪表 | 3篇 |
建筑科学 | 42篇 |
矿业工程 | 1篇 |
能源动力 | 14篇 |
轻工业 | 82篇 |
水利工程 | 1篇 |
石油天然气 | 11篇 |
无线电 | 12篇 |
一般工业技术 | 53篇 |
冶金工业 | 64篇 |
自动化技术 | 49篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 17篇 |
2021年 | 12篇 |
2020年 | 10篇 |
2019年 | 7篇 |
2018年 | 12篇 |
2017年 | 7篇 |
2016年 | 3篇 |
2015年 | 11篇 |
2014年 | 13篇 |
2013年 | 23篇 |
2012年 | 17篇 |
2011年 | 25篇 |
2010年 | 18篇 |
2009年 | 31篇 |
2008年 | 30篇 |
2007年 | 29篇 |
2006年 | 19篇 |
2005年 | 16篇 |
2004年 | 19篇 |
2003年 | 17篇 |
2002年 | 12篇 |
2001年 | 11篇 |
2000年 | 12篇 |
1999年 | 9篇 |
1998年 | 8篇 |
1997年 | 5篇 |
1996年 | 9篇 |
1995年 | 5篇 |
1994年 | 11篇 |
1993年 | 5篇 |
1992年 | 6篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1985年 | 3篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1975年 | 2篇 |
1972年 | 2篇 |
1967年 | 2篇 |
1954年 | 1篇 |
1944年 | 2篇 |
1943年 | 1篇 |
排序方式: 共有511条查询结果,搜索用时 15 毫秒
91.
92.
Mass spectrometry (MS) is increasingly being used for metabolic profiling, but detection modes such as constant neutral loss or multiple reaction monitoring have not often been reported. These modes allow focusing on structurally related compounds, which could be advantageous for situations in which the trait under investigation is associated with a particular class of metabolites. In this study, we analyzed endogenous glucuronides excreted in human urine by monitoring characteristic transitions of putative steroid glucuronides by LC-MS/MS for discrimination of females from males. Two methods for data extraction were used: (i) a manual procedure based on visual inspection of the chromatograms and selection of 23 peaks and (ii) a software-supported method (MarkerView) set to extract 100 peaks. Data from 10 female and 10 male students were analyzed by principal component analysis (PCA) and partial least-squares discriminant analysis (PLS-DA) using software SIMCA. With PCA, only the manual peak selection resulted in clustering males and females. With PLS-DA, the manual method provided full separation on the basis of one single discriminant; the software-supported approach required a two-component model for complete separation. Loading plots were analyzed for their ability to reveal peaks with high discriminating power, that is, potential biomarkers. The PLS-DA models were validated with urine samples collected from five new females and five new males. Gender was correctly assigned for all. Our results indicate that inclusion of biological criteria for variable selection coupled to class-specific MS analysis and data extraction by appropriate software may constitute a valuable addition to the methods available for metabolomics. 相似文献
93.
Rafal Strzalka Tobias Gabriel Erhart Ursula Eicker 《Applied Thermal Engineering》2013,50(2):1418-1426
The paper deals with analysis and optimization of the performance of the combustion process in a biomass furnace at a biomass cogeneration plant. For the purpose a thermodynamic model for the biomass burning process in a grate furnace was developed. The mathematical model describes both, the thermal decomposition of the fuel on the grate as well as gas phase combustion in the secondary zone. The presented approach is based on energy equations for each individual step of the biomass combustion process.Measurement results from a biomass-fired cogeneration plant were used to validate the model. Comparison between simulation and measurement results shows good agreement. The model predicts accurately the temperature profiles in the combustion chamber.The presented approach is suitable for model based analysis and optimization of control strategies. The developed model was used to optimize the performance of the recirculation system of the combustion appliance. The simulation based analysis showed, that the flow rate of the recirculated exhaust fumes can be significantly reduced which results in energy savings of 17% of the auxiliary electrical power demand. 相似文献
94.
Nuclear quantum dynamics beyond the Born-Oppenheimer approximation is performed using quantum trajectories. Withintheadiabaticrepresentationoftheelectronicstates, NABDY(NonAdiabaticBohmianDYnamics) is used in combination with DFT and LR-TDDFT to perform on-the-fly nonadiabatic quantum dynamics. Simple numerical test systems and current limitations of the method are discussed. 相似文献
95.
The neurosurgical method of deep brain stimulation (DBS) is used to treat symptoms of movement disorders like Parkinson's disease by implanting stimulation electrodes in deep brain areas. The aim of this study was to examine the field distribution in DBS and the role of heterogeneous and anisotropic material properties in the brain areas where stimulation is applied. Finite element models of the human brain were developed comprising tissue heterogeneity and anisotropy. The tissue data were derived from averaged magnetic resonance imaging and diffusion tensor imaging datasets. Unilateral stimulation of the subthalamic nucleus (STN) was computed using an accurate model of an electrode used in clinical treatment of DBS extended with an encapsulation layer around the electrode body. Computations of anisotropic and isotropic brain models, which consider resistive tissue properties for unipolar and bipolar electrode configurations, were carried out. Electrode position was varied within an area around the stimulation center. Results have shown a deviation of 2% between anisotropic and isotropic field distributions in the vicinity of the STN. The sensitivity of this deviation referring to the electrode position remained small, but increased when the electrode position approached areas of high anisotropy. 相似文献
96.
97.
Debruille J. Bruno; Brodeur Mathieu B.; Hess Ursula 《Canadian Metallurgical Quarterly》2011,11(3):533
[Correction Notice: An erratum for this article was reported in Vol 11(4) of Emotion (see record 2011-13790-001). Figure 1 should have been printed in color.] [Correction Notice: An erratum for this article was reported in Emotion July 4 2011 (see record 2011-13790-001). Figure 1, which should have been printed in color, was inadvertently printed in black and white. The online version has been corrected.] Faces of unknown persons are processed to infer the intentions of these persons not only when they depict full-blown emotions, but also at rest, or when these faces do not signal any strong feelings. We explored the brain processes involved in these inferences to test whether they are similar to those found when judging full-blown emotions. We recorded the event-related brain potentials (ERPs) elicited by faces of unknown persons who, when they were photographed, were not asked to adopt any particular expression. During the ERP recording, participants had to decide whether each face appeared to be that of a positively, negatively, ambiguously, or neutrally intentioned person. The early posterior negativity, the EPN, was found smaller for neutrally categorized faces than for the other faces, suggesting that the automatic processes it indexes are similar to those evoked by full-blown expressions and thus that these processes might be involved in the decoding of intentions. In contrast, in the same 200–400 ms time window, ERPs were not more negative at anterior sites for neutrally intentioned faces. Second, the peaks of the late positive potentials (LPPs) maximal at parietal sites around 700 ms postonset were not significantly smaller for neutrally intentioned faces. Third, the slow positive waves that followed the LPP were larger for faces that took more time to categorize, that is, for ambiguously intentioned faces. These three series of unexpected results may indicate processes similar to those triggered by full-blown emotions studies, but they question the characteristics of these processes. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
98.
Amstad Fabienne T.; Meier Laurenz L.; Fasel Ursula; Elfering Achim; Semmer Norbert K. 《Canadian Metallurgical Quarterly》2011,16(2):151
A literature review of studies analyzing work–family conflict and its consequences was conducted, and 427 effect sizes were analyzed meta-analytically. Work–family conflict was analyzed bidirectionally in terms of work interference with family (WIF) and family interference with work (FIW). We assessed 3 categories of potential outcomes: work-related outcomes, family-related outcomes, and domain-unspecific outcomes. Results show that WIF and FIW are consistently related to all 3 types of outcomes. Both types of interrole conflict showed stronger relationships to same-domain outcomes than to cross-domain outcomes. Thus, WIF was more strongly associated with work-related than with family-related outcomes, and FIW was more strongly associated with family-related than with work-related outcomes. In moderator analyses, parenthood could not explain variability in effect sizes. However, time spent at work did moderate the relationships between WIF and family-related outcomes, as well as FIW and domain-unspecific outcomes. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
99.
100.
Markus Takkunen Jyrki Ågren Johanna Kuusisto Markku Laakso Matti Uusitupa Ursula Schwab 《Lipids》2013,48(11):1093-1102
Erythrocyte membrane fatty acid (EMFA) composition is used in the validation of food frequency questionnaires (FFQ) and the evaluation of dietary fat quality. In this cross-sectional study we aimed to investigate associations of diet with EMFA. Altogether, 1,033 randomly selected Finnish men, aged from 47 to 75 years filled in a FFQ and their EMFA composition was analyzed. Marine polyunsaturated fatty acid (PUFA) intake correlated positively with erythrocyte eicosapentaenoic and docosahexaenoic acids (r s = 0.415 and r s = 0.340, respectively, P < 0.001) and inversely with all n-6 PUFA analyzed (P < 0.001). PUFA intake from spreads and cooking fats correlated positively with alpha-linolenic (ALA), linoleic (LNA) and nervonic acids (r s = 0.229, r s = 0.160 and r s = 0.143, respectively, P < 0.001). Milk fat intake was associated with myristic and behenic acids (r s = 0.186 and r s = 0.132, respectively P < 0.001). Butter users had lower ALA and LNA proportions (mol%) than non-users (0.16 ± 0.04 vs. 0.19 ± 0.05, P < 0.001 and 7.77 ± 1.02 vs. 8.12 ± 1.11, P = 0.001). Higher PUFA intake from meat was related to decreased long-chain n-3 (P < 0.001) and increased n-6 PUFA (P < 0.001) proportions. In conclusion, EMFA composition reflects particularly well the intakes of n-3 PUFA, whereas other associations remained lower. Yet, all main sources of dietary fat were related with EMFA. The dietary effect on the nervonic acid proportion was confirmed. 相似文献