全文获取类型
收费全文 | 955篇 |
免费 | 66篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 15篇 |
化学工业 | 277篇 |
金属工艺 | 12篇 |
机械仪表 | 11篇 |
建筑科学 | 23篇 |
矿业工程 | 2篇 |
能源动力 | 29篇 |
轻工业 | 204篇 |
水利工程 | 8篇 |
石油天然气 | 2篇 |
武器工业 | 1篇 |
无线电 | 49篇 |
一般工业技术 | 124篇 |
冶金工业 | 127篇 |
原子能技术 | 2篇 |
自动化技术 | 138篇 |
出版年
2024年 | 1篇 |
2023年 | 7篇 |
2022年 | 29篇 |
2021年 | 62篇 |
2020年 | 26篇 |
2019年 | 28篇 |
2018年 | 32篇 |
2017年 | 34篇 |
2016年 | 42篇 |
2015年 | 39篇 |
2014年 | 45篇 |
2013年 | 66篇 |
2012年 | 68篇 |
2011年 | 54篇 |
2010年 | 60篇 |
2009年 | 55篇 |
2008年 | 35篇 |
2007年 | 41篇 |
2006年 | 38篇 |
2005年 | 22篇 |
2004年 | 19篇 |
2003年 | 20篇 |
2002年 | 17篇 |
2001年 | 8篇 |
2000年 | 8篇 |
1999年 | 7篇 |
1998年 | 52篇 |
1997年 | 31篇 |
1996年 | 16篇 |
1995年 | 11篇 |
1994年 | 9篇 |
1993年 | 9篇 |
1992年 | 5篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1986年 | 4篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1977年 | 3篇 |
1976年 | 4篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有1024条查询结果,搜索用时 15 毫秒
941.
José Miguel Flores-Fernández Enrique J. Herrera-López Francisco Sánchez-Llamas Antonio Rojas-Calvillo Paula Anel Cabrera-Galeana Gisela Leal-Pacheco María Guadalupe González-Palomar R. Femat Moisés Martínez-Velázquez 《Expert systems with applications》2012,39(12):10851-10856
Lung cancer is a public health priority worldwide due to the high mortality rate and the costs involved. Early detection of lung cancer is important for increasing the survival rate, however, frequently its diagnosis is not made opportunely, since detection methods are not sufficiently sensitive and specific. In recent years serum biomarkers have been proposed as a method that might enhance diagnostic capabilities and complement imaging studies. However, when used alone they show low sensitivity and specificity because lung cancer is a heterogeneous disease. Recent reports have shown that simultaneous analysis of biomarkers has the potential to separate lung cancer patients from control subjects. However, it has become clear that a universal biomarker panel does not exist, and optimized panels need to be developed and validated in each population before their application in a clinical setting. In this study, we selected 14 biomarkers from literature, whose diagnostic or prognostic value had been previously demonstrated for lung cancer, and evaluated them in sera from 63 patients with lung cancer and 87 non-cancer controls (58 Chronic Obstructive Pulmonary Disease (COPD) patients and 29 current smokers). Principal component analysis and artificial neural network modeling allowed us to find a reduced biomarker panel composed of Cyfra 21.1, CEA, CA125 and CRP. This panel was able to correctly classify 135 out of 150 subjects, showing a correct classification rate for lung cancer patients of 88.9%, 93.3% and 90% in training, validation and testing phases, respectively. Thus, sensitivity was increased 18.31% (sensitivity 94.5% at specificity 80%) with respect to the best single marker Cyfra 21.1. This optimized panel represents a potential tool for assisting lung cancer diagnosis, therefore it merits further consideration. 相似文献
942.
Thin films of the composites formed between poly(vinylidene fluoride) (PVDF) and lead zirconium titanate (PZT) and also barium titanate with 0–3 connectivity, have been obtained by dispersion of the ceramic powder in a solution of PVDF in dimethylacetamide DMA. Evaporation of the solvent at 65 °C allowed crystallization of PVDF predominantly in the polar phase, regardless of the amount of PZT or BaTiO3 powder added upto 40 vol %. The relative permittivity and loss index values were determined for the pure components and for the composites with different ceramic contents, in the frequency range of 100 Hz to 13 MHz. An increase in PZT or BaTiO3 content resulted in an increase in the relative permittivity of the composites, and the experimental results are shown to be in good agreement with those calculated from the theoretical expression of Yamada et al. [1]. The de electrical conductivity of composites with different compositions was also determined. 相似文献
943.
In this paper, we derive explicit formulas of the Rényi information, Shannon entropy and Song measure for the invariant density of one dimensional ergodic diffusion processes. In particular, the diffusion models considered include the hyperbolic, the generalized inverse Gaussian, the Pearson, the exponential family and a new class of skew-t diffusions. 相似文献
944.
Cotelli M.; Borroni B.; Manenti R.; Alberici A.; Calabria M.; Agosti C.; Arévalo A.; Ginex V.; Ortelli P.; Binetti G.; Zanetti O.; Padovani A.; Cappa S. F. 《Canadian Metallurgical Quarterly》2006,20(5):558
Action naming has been reported to be disproportionately impaired in comparison to object naming in patients with frontotemporal dementia (FTD). This finding has been attributed to the crucial role of frontal cortex in action naming. The investigation of object and action naming in the different subtypes of FTD, as well as in the related conditions of progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD), may thus contribute to the elucidation of the cerebral correlates of the action-object discrepancy as well as provide clues to the underlying cognitive mechanisms. The results indicated that, with the exception of semantic dementia, action naming was more impaired than object naming in all patient groups. The discrepancy was similar in frontal variant of FTD and Alzheimer's disease patients, whereas patients with nonfluent primary progressive aphasia, PSP, and CBD were significantly more impaired in the oral production of actions than of objects. These findings indicate that action naming impairment is not a general feature of FTD, but rather is associated with conditions that affect the frontoparietal-subcortical circuits involved in action knowledge and action representation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
945.
Charalampos Pitsalidis Anna‐Maria Pappa Mintu Porel Christine M. Artim Gregorio C. Faria Duc D. Duong Christopher A. Alabi Susan Daniel Alberto Salleo Róisín M. Owens 《Advanced materials (Deerfield Beach, Fla.)》2018,30(39)
Antibiotic discovery has experienced a severe slowdown in terms of discovery of new candidates. In vitro screening methods using phospholipids to model the bacterial membrane provide a route to identify molecules that specifically disrupt bacterial membranes causing cell death. Thanks to the electrically insulating properties of the major component of the cell membrane, phospholipids, electronic devices are highly suitable transducers of membrane disruption. The organic electrochemical transistor (OECT) is a highly sensitive ion‐to‐electron converter. Here, the OECT is used as a transducer of the permeability of a lipid monolayer (ML) at a liquid:liquid interface, designed to read out changes in ion flux caused by compounds that interact with, and disrupt, lipid assembly. This concept is illustrated using the well‐documented antibiotic Polymixin B and the highly sensitive quantitation of permeability of the lipid ML induced by two novel recently described antibacterial amine‐based oligothioetheramides is shown, highlighting molecular scale differences in their disruption capabilities. It is anticipated that this platform has the potential to play a role in front‐line antimicrobial compound design and characterization thanks to the compatibility of semiconductor microfabrication technology with high‐throughput readouts. 相似文献
946.
This paper investigates a multi-objective parallel machine scheduling problem under fully fuzzy environment with fuzzy job deterioration effect, fuzzy learning effect and fuzzy processing times. Due dates are decision variables for the problem and objective functions are to minimise total tardiness penalty cost, to minimise earliness penalty cost and to minimise cost of setting due dates. Due date assignment problems are significant for Just-in-Time (JIT) thought. A JIT company may want to have optimum schedule by minimising cost combination of earliness, tardiness and setting due dates. In this paper, we compare different approaches for modelling fuzzy mathematical programming models with a local search algorithm based on expected values of fuzzy parameters such as job deterioration effect, learning effect and processing times. 相似文献
947.
VO Ezenwa JM Peters Y Zhu E Arévalo MD Hastings P Sepp? JS Pedersen F Zacchi DC Queller JE Strassmann 《Canadian Metallurgical Quarterly》1998,10(2):168-177
Several recent pieces of clinical evidence have demonstrated that reduction of cholesterol levels positively affects outcomes in both primary and secondary prevention of atherosclerotic vascular disease. The mechanism for the beneficial effects of cholesterol-lowering interventions has been attributed to decreased progression or actual regression of plaques as a consequence of reduced circulating LDL concentrations. Other mechanisms can be hypothesized, including a "stabilizing" effect on plaques, which would decrease chances of rupture, and an improvement of endothelial dysfunction, which would slow-down the progression of the disease. This review is aimed at offering an update on such mechanisms. The hypothesis of a direct action of cholesterol-lowering agents, in particular of statins, on endothelial functions, independently of LDL-lowering effects, will be discussed. 相似文献
948.
Bernabé Gregorio Hernández Raúl Acacio Manuel E. 《The Journal of supercomputing》2018,74(4):1765-1778
The Journal of Supercomputing - Current low-cost general-purpose single-board computing (SDC) devices are gaining increasing interests in research computing due to their very low cost/performance... 相似文献
949.
A kinetic analysis in a variety of conditions (gas composition and temperature) has been conducted on catalysts of iron oxides supported on activated carbon fiber composites (ACFC). Additionally, experiments of temperature-programmed desorption (TPD) of NO were conducted on the catalysts in order to reveal mechanistic features of the low-temperature SCR reaction. In the light of current SCR literature and previous work, a qualitative picture of the catalytic behavior of low-temperature SCR catalysts is offered. Apparently, the strength of adsorption of NO during the low-temperature SCR reaction is responsible for the governing reaction mechanism. Thus, highly stable nitrates formed on the surface provoke catalyst deactivation and reaction through an ER mechanism, with NO reacting from the gas phase, whereas the absence of these nitrates permits reaction of less stable nitrites from the catalyst surface, following an LH-type mechanism. This is the case for the ACFC-supported iron oxide catalyst analyzed in this work. 相似文献
950.
The purpose of this study was to define the dietary pattern of fatty acids, cholesterol, fiber and sucrose in a random sample of 51 families of San José, Costa Rica. Food intake was estimated by using the one-day food weighing method. For food composition values, a single table was created using data taken from others. The results indicated that the level of macronutrient diet composition was in accordance with the United States National Cholesterol Education Program Recommendations. Nevertheless, total dietary fiber (20.3 g/d) intake was below the level suggested by the guidelines, and the percentage of calories from sucrose (12.6%) was above those recommendations. In conclusion, the low P/S ratio, low dietary fiber and high percentage of calories from sucrose in the diet of this urban population group of San José, has several atherogenic features representing one of the important risk factors associated with cardiovascular disease. 相似文献