全文获取类型
收费全文 | 99篇 |
免费 | 8篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 16篇 |
机械仪表 | 2篇 |
建筑科学 | 4篇 |
能源动力 | 1篇 |
轻工业 | 8篇 |
无线电 | 5篇 |
一般工业技术 | 16篇 |
冶金工业 | 33篇 |
自动化技术 | 20篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 6篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 8篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 12篇 |
2012年 | 8篇 |
2011年 | 7篇 |
2010年 | 1篇 |
2009年 | 1篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 1篇 |
1999年 | 1篇 |
1998年 | 11篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有107条查询结果,搜索用时 234 毫秒
31.
L Almenar S Martí I Roldán V Miró JL Díez A Osa M Palencia F Algarra 《Canadian Metallurgical Quarterly》1996,49(6):423-431
AIM: The purpose of the study was to analyse echocardiographic, electrocardiographic and clinical variables in patients with hypertrophic cardiomyopathy, as well as to compare the possible differences between the non-obstructive (NOHCM) and the obstructive form (OHCM). METHOD: 44 consecutive patients were studied and diagnosed with hypertrophic cardiomyopathy (NOHCM 26 and OHCM 18). The following variables were analysed: 1) echocardiographic: right ventricle (RV), interventricular septum (IVS), posterior wall (pW), telediastolic and telesystolic diameter of the left ventricle (TDD-LV and TSD-LV), size of the left atrium (LA), systolic anterior motion of the mitral valve (SAM), mitral insufficiency and direction of the jet (MI and MIpW), mitral anular calcium (MAC), filling pattern (A > E); 2) electrocardiographic: repolarization disorders (RD), left ventricular hypertrophy (LVH), negative "T" waves in the precordial leads (T-), pathological "q" waves, super or ventricular arrhythmias (SA or VA), short PR, right or left bundle branch block (RBBB and LBBB), and 3) clinical: presence of dyspnea, angina, syncope, palpitations and response to treatment with beta-blockers (B-b) or Calcium-antagonists (C-A). RESULTS: There were no differences in age or sex between the obstructive and non-obstructive groups: 1) echocardiographic differences: there were none in RV, pW, TDD-LV, LA nor A > E wave. Significant differences were found (p < 0.05) in the rest of the variables; IVS (16 +/- 3 mm in NOHCM vs 22 +/- 5 mm in OHCM), TSD-LV (26 +/- 5 mm in NOHCM vs 22 +/- 6 mm in OHCM), SAM (38% in NOHCM vs 89% in OHCM), MI (19% in NOHCM vs 78% in OHCM), MIpW (20% in NOHCM vs 79% in OHCM), MAC (15% in NOHCM vs 44% in OHCM); 2) electrocardiographic differences: there were none in the presence of RD, pathological "q", VA, short PR, RBBB nor LBBB. The presence of "T" negatives was on the limit of significance in the precordial leads (31% in NOHCM vs 11% in OHCM; p = 0.09). Differences were found in the rest of the variables; LVH (58% in NOHCM vs 83% in OHCM), SA (50% in NOHCM vs 17% in OHCM); 3) clinical differences: there were none in the presence of dyspnea, angina, syncope or palpitations. Differences were found in the improvement with treatment; B-b (60% in NOHCM vs 57% in OHCM), C-A (100% in NOHCM vs 100% in OHCM). CONCLUSIONS: 1) in our patients, the most frequent cardiomyopathy is the non-obstructive one, with no predominance of age or sex; 2) in OHCM, IVS is much wider, with smaller TSD-LV, there is a greater incidence of MI, generally directed towards the posterior wall of the left atrium, and a larger tendency to calcify the mitral annulus; 3) the most frequent electrocardiographic abnormality is the alteration of repolarization. NOHCM has a greater incidence of SA and a lower degree of LVH with more prevalence of negative "T" waves in the precordial leads; 4) there are no clinical parameters differentiating the two groups, although the sustained improvement obtained with treatment is more likely to be produced by the calcium-antagonists than by beta-blockers in both types of cardiomyopathy. 相似文献
32.
Picosecond Capture of Photoexcited Electrons Improves Photovoltaic Conversion in MAPbI3:C70‐Doped Planar and Mesoporous Solar Cells
下载免费PDF全文
![点击此处可从《Advanced materials (Deerfield Beach, Fla.)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Saba Gharibzadeh Franco Valduga de Almeida Camargo Cristina Roldán‐Carmona Grégoire Clément Gschwend Jorge Pascual Ramón Tena‐Zaera Giulio Cerullo Giulia Grancini Mohammad Khaja Nazeeruddin 《Advanced materials (Deerfield Beach, Fla.)》2018,30(40)
In this work, solar cells based on methylammonium lead iodide (MAPbI3) doped in solution with C70 fullerene in a mesoporous as well as planar electron‐transporting layer (ETL)‐free architecture are realized, showcasing in the latter case a record efficiency of 15.7% and an improved open‐circuit voltage (VOC). Contrary to the bulk heterojunction previously reported, the C70 molecules do not phase segregate and they are rather finely dispersed in the perovskite film, possibly infiltrating at the grain boundaries, while assisting the growth of a highly uniform perovskite layer. By means of time‐resolved femtosecond‐to‐nanosecond optical spectroscopy, with an extended spectral coverage, it is observed that electrons photogenerated in the perovskite are transferred to C70 with a time constant of 20 ps. Despite being captured by C70, electrons are not deeply trapped and can potentially bounce back into the perovskite, as suggested by the high fill factor and enhanced VOC of the MAPbI3:C70 solar cells, especially in the case of the ETL‐free device configuration. 相似文献
33.
Abstract We analyse the solution of the coined quantum walk on a line. First, we derive the full solution, for arbitrary unitary transformations, by using a new approach based on the four ‘walk fields’ which we show determine the dynamics. The particular way of deriving the solution allows a rigorous derivation of a long wavelength approximation. This long wavelength approximation is useful as it provides an approximate analytical expression that captures the basics of the quantum walk and allows us to gain insight into the physics of the process. 相似文献
34.
Ultrasonic‐Assisted Extraction of Phenols,Flavonoids, and Biocompounds with Inhibitory Effect Against Salmonella Typhimurium and Staphylococcus Aureus from Cactus Pear
下载免费PDF全文
![点击此处可从《Journal of food process engineering》网站下载免费的PDF全文](/ch/ext_images/free.gif)
35.
Characterisation of thermal barrier coatings and ultra high temperature composites deposited in a low pressure plasma reactor 总被引:1,自引:0,他引:1
C. FourmondG. Da Rold F. Rousseau C. GuyonS. Cavadias D. MorvanR. Mévrel 《Journal of the European Ceramic Society》2011,31(13):2295-2302
A low pressure plasma process working at 600-800 Pa was used to deposit from aqueous solution ZrO2-4 mol% Y2O3 (Yttria partially stabilized Zirconia-YpSZ) layers and stacks of Ta2O5/YpSZ layers for use as thermal barrier coatings (TBC). The observation of the cross section revealed a high porosity. The thermal diffusivity of the layers (1 × 10−7 m2 s−1) was measured by a laser flash technique and compared with values obtained on air plasma sprayed material (3 × 10−7 m2 s−1). The plasma reactor were also used to deposit ZrB2-ZrO2-SiC layers used as Ultra High Temperature Composite (UHTC) from aqueous solutions of zirconyl and Boron nitrates containing suspensions of SiC. Layers up to 100 μm thick were obtained on SiC substrates. XRD was used to study the crystallinity of the layer. The presence of ZrB2 and SiC phases was confirmed after the deposition. XRD analysis showed that heat treatment at 1073 K under oxidizing conditions led to the loss of ZrB2 and the appearance of ZrO2 phases. To understand the behaviour of the layers to interaction with atomic oxygen (combustion for TBC and spacecraft re-entry phase for UHTC), we have measured the atomic oxygen recombination coefficient to determine the number of adsorption sites on the surface of the coatings. This was accomplished by using a low pressure plasma reactor coupled with optical spectroscopic measurements as a diagnostic technique. 相似文献
36.
Laura Roldán Iván Santos Sabino Armenise José María Fraile Enrique García-Bordejé 《Carbon》2012,50(3):1363-1372
A hydrothermal carbon layer has been coated on graphite felt using a carbohydrate solution (glucose, sucrose or starch) as precursor. The coating is uniform in thickness and coverage, and exhibits excellent adhesion to the substrate. It is highly hydrophilic, very accessible to reactants and the thickness can be tuned by the synthesis conditions. The coating was functionalized with sulfonic acid groups and its morphology and surface chemistry characterized by SEM, TPO-MS, IR-spectroscopy and XPS. The sulfonated material has been tested in the esterification of palmitic acid with methanol exhibiting significant activity and stability. 相似文献
37.
Inés Coleto Rafael Roldán César Jiménez-Sanchidrián Juan P. Gómez Francisco J. Romero-Salguero 《Catalysis Today》2010,149(3-4):275-280
Several catalysts consisting of Pt supported on sulfated or tungstated zirconia (one of them supported on alumina) have been characterized by different techniques, such as elemental and XRD analyses, N2 adsorption, TPD of ammonia, TPR and H2 chemisorption. All these catalysts were active in the transformation of two α-olefins, 1-pentene and 1-hexene, both present in most of FCC naphthas, whose conversion to internal and branched olefins is of a great interest for their use in reformulated gasolines and as intermediate chemicals. At low reaction temperatures (200–250 °C), both hydrogenation and double bond shift compete to give n-paraffins and internal olefins, respectively. As the temperature rises (>350 °C) the catalytic activity for the isomerization reactions increases, yielding a higher amount of internal and branched olefins. The product composition depends on the particular catalyst and reaction conditions used. The high activity of the sulfated zirconia, is remarkable and clearly indicates the participation of acid sites in these reactions. 相似文献
38.
This paper deals with the simultaneous determination of the quaternary mixture of tocopherols (alpha-, beta-, gamma-, and delta-T) performed using fluorimetric techniques and partial least squares (PLS-1) multivariate analysis. In this study, PLS-1 was applied to matrices made up of fluorescence excitation and emission spectra (EEM) and with fluorescence excitation, emission, and synchronous spectra (EESM) of tocopherols dissolved in hexane: diethyl ether (70:30 v/v). A calibration set of 55 samples based in a central composite plus a full factorial plus a fractionated factorial design was constructed. When synthetic samples were analyzed, recoveries around 100% were obtained and detection limits were calculated using EEM and EESM. For the analysis of the oils, the samples, diluted in hexane, were cleaned in silica cartridges and tocopherols were eluted with hexane: diethyl ether (90:10 v/v). The developed method was applied to different edible oils. The results are satisfactory for alpha-, beta-, and gamma-, but they are worse for delta-T. 相似文献
39.
40.
Due to its location and functions, the tongue is one of the most important anatomic structures in the oral cavity. However, knowledge in regards to its role and implications in oral health and disease is scarce. Moreover, although the dorsum of the tongue seems to harbour one of the most complex microbiological niches in human ecology, the knowledge of the role of tongue flora in health and disease is also very limited. Similarly, the nature of the tongue coating and the factors that influence its development and composition are almost unknown. The interest in the study of the tongue niche has increased in recent years due to its association with oral halitosis and to its role as a suitable reservoir for periodontal pathogens. The structure of the tongue favours a unique and complex bacterial biofilm, in which periodontal pathogens are frequently found. However, little is known about how to control this bacterial niche, and factors affecting tongue coating composition and aspect are not fully understood. Studies available on the influence of mechanical or antimicrobial approaches against tongue biofilm are very limited. Mechanical treatments showed a transient reduction in halitosis-related variables but were limited in time. Different antimicrobials agents have been evaluated: chlorhexidine, chlorine dioxide, metal ions, triclosan, formulations containing essential oils, and hydrogen peroxide. However, most studies were designed as short-term models. Some of these studies demonstrated that the reduction in halitosis-related variables was associated with significant changes in the tongue microflora. 相似文献