全文获取类型
收费全文 | 494篇 |
免费 | 47篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 5篇 |
综合类 | 3篇 |
化学工业 | 132篇 |
金属工艺 | 6篇 |
机械仪表 | 15篇 |
建筑科学 | 15篇 |
矿业工程 | 2篇 |
能源动力 | 22篇 |
轻工业 | 101篇 |
水利工程 | 11篇 |
石油天然气 | 11篇 |
无线电 | 55篇 |
一般工业技术 | 76篇 |
冶金工业 | 32篇 |
原子能技术 | 3篇 |
自动化技术 | 57篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 24篇 |
2021年 | 37篇 |
2020年 | 24篇 |
2019年 | 30篇 |
2018年 | 31篇 |
2017年 | 37篇 |
2016年 | 31篇 |
2015年 | 19篇 |
2014年 | 32篇 |
2013年 | 41篇 |
2012年 | 29篇 |
2011年 | 46篇 |
2010年 | 30篇 |
2009年 | 12篇 |
2008年 | 13篇 |
2007年 | 12篇 |
2006年 | 11篇 |
2005年 | 10篇 |
2004年 | 13篇 |
2003年 | 6篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有546条查询结果,搜索用时 15 毫秒
121.
Decision‐tree‐based methods for differential diagnosis of β‐thalassemia trait from iron deficiency anemia
下载免费PDF全文
![点击此处可从《Expert Systems》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Mina Jahangiri Elahe Khodadi Fakher Rahim Najmaldin Saki Amal Saki Malehi 《Expert Systems》2017,34(3)
Several discrimination indices have been proposed to distinct between β‐thalassemia trait (βTT) and iron deficiency anemia (IDA). This study is the first application of tree‐based methods for differential diagnosis of βTT from IDA. One hundred forty‐four patients with hypochromic microcytic anemia aged 18–40 years old from Ayat Hospital of Tehran were recruited. Classification and Regression tree, CHi‐squared Automatic Interaction Detector (CHAID), Exhaustive CHi‐squared Automatic Interaction Detector (E‐CHAID), Quick, Unbiased, Efficient Statistical Tree (QUEST), Classification Rule with Unbiased Interaction Selection and Estimation (CRUISE), and Generalized, Unbiased, Interaction Detection and Estimation (GUIDE) have been used to discriminate the diagnosis. Mean corpuscular volume (MCV) was found as the main predictor in discrimination. All the mentioned tree‐based methods showed acceptable sensitivity, specificity, accuracy, Youden's index, false positive and negative rate, positive and negative predictive values and AUC in differential diagnosis of βTT from IDA. However, Classification Rule with Unbiased Interaction Selection and Estimation revealed more precise classification with an area under the curve value of 0.99. Decision‐tree‐based methods can be used to develop sensitive and accurate diagnostic methods for differentiating βTT from IDA. 相似文献
122.
In this paper, a design of product polar quantizers for A/D (analog-to-digital) conversion of measurement signals and an analysis of their performances in the wide range of variances are considered, in a general manner, i.e. for any compression function. Special attention is devoted to the design of robust product polar quantizers, applying the developed theory on μ-law logarithmic compression function, which is very important since a lot of measurement signals are nonstationary. The proposed quantizers achieve much better performances than scalar quantizers (they have higher the maximal SQNR (signal-to-quantization noise ratio) for about 2.5 dB and they are more robust), without increasing of complexity. Theory is proved by simulation. These quantizers can be applied for many different types of measurement signals and can be used in many measurement systems (telemetry, telemedicine, wireless sensor networks, etc.). 相似文献
123.
Prakash Gajurel Mina Kim Qiang Wang Weitao Dai Haitao Liu Cheng Cen 《Advanced functional materials》2017,27(47)
Defects‐controlled friction in graphene is of technological importance in many applications, but the underlying mechanism remains a subject of debate. Here it is shown that, during the controlled oxidation in oxygen plasma and subsequent reduction induced by high‐energy photons, the contact friction in chemical vapor deposition grown graphene is dominantly determined by the vacancies formed instead of the bonding with add‐atoms. This effect is attributed to the vacancy‐enhanced out‐of‐plane deformation flexibility in graphene, which tends to produce large puckering of graphene sheet near the contact edge and thus increases the effective contact area. Modified graphene with large contact friction has a large density of defects, but remains a good electrical conductor, in which the carrier transport is strongly affected by quantum localization effects even at room temperature. It is also found that the oxidation process in graphene is substrate‐sensitive. Comparing to monolayer graphene on SiO2 substrate, the oxidation process progresses much faster when the substrate is SrTiO3, while bilayer graphene exhibits great oxidation resistance on both substrates. The collection of observations provides important information for tailoring the mechanical, electrical, and chemical properties of graphene through selected defects and substrates. 相似文献
124.
Antonín Minařík Martin Perůtka Pavel Urban Lubomír Lapčík Martin Juřička 《International Journal of Heat and Mass Transfer》2010,53(23-24):5472-5477
Special micro-condensation drying system (MCDS) was constructed for precise preparation of self-organized polymeric layers by casting from solutions and dispersions at highly non-equilibrium conditions. There were respected the needs for exact regulation of temperature, temperature gradient and rate of solvent evaporation, vibration damping, dust-free design and wide variability in process parameters settings as well. MCDS allows to study a broad spectrum of effects determining creation of self-organized structures during the evaporation of solvent from the polymer solution (e.g. Rayleigh–Bénard or Bénard–Marangoni cells). As a model system for MCDS functionality testing aqueous solution of hydroxyethyl-cellulose was chosen, with respect to its excellent film-forming properties and the self-organization ability. All of this is observable in high number of cell patterns, originating according to the process parameters, in the given polymer-solution system. 相似文献
125.
Mina K. Kim Pil‐Woo Nam Seung‐Joo Lee Kwang‐Geun Lee 《Journal of the Institute of Brewing》2014,120(4):537-542
Antioxidant activities of traditionally brewed Korean rice wines have recently been reported. The objective of this study was to identify the antioxidant activities of the volatile and non‐volatile fractions of three Korean rice wines, and further to identify the active ingredients responsible for the antioxidant properties. Volatile and non‐volatile components of three rice wines, Measilju, Kukwhaju and Gugijaju, were separated into seven fractions according to their polarities. Antioxidant activities were determined by an aldehyde–carboxylic acid assay for the volatile fractions and a lipid–malondialdehyde assay for the non‐volatile fractions. Volatile constituents of each fraction were identified and quantified using gas chromatography–mass spectrometry. In addition, antioxidant activities of specific authentic chemicals from the volatile fractions of the wines were measured, and the antioxidant properties of the volatile fractions were determined. Identification of volatile compounds potentially showing high antioxidant activities were conducted in each fraction of the three wines. Among the volatile compounds identified from volatile fractions of the wines, benzeneethanol, 2‐furanmethanol and 4‐ethyl‐2methoxyphenol showed the highest antioxidant activities, when added at higher concentrations (~100 µg/g). Identification of antioxidant properties, as well as the specific compounds responsible for these antioxidant properties, could aid Korean rice wine product developers, in terms of strategic planning for sales in the Korean market. Copyright © 2014 The Institute of Brewing & Distilling 相似文献
126.
Molajou Amir Nourani Vahid Afshar Abbas Khosravi Mina Brysiewicz Adam 《Water Resources Management》2021,35(8):2369-2384
Water Resources Management - Rainfall-runoff (r-r) modeling at different time scales is considered as a significant issue in hydro-environmental planning. As a first hydrological implementation,... 相似文献
127.
Amir Houshang Mahmoudi Mina Shahi Abed Moheb Shahedin Neda Hemati 《International Communications in Heat and Mass Transfer》2011,38(1):110-118
This paper presents a numerical study of natural convection cooling of two heat sources vertically attached to horizontal walls of a cavity. The right opening boundary is subjected to the copper–water nanofluid at constant low temperature and pressure, while the other boundaries are assumed to be adiabatic. The governing equations have been solved using the finite volume approach, using SIMPLE algorithm on the collocated arrangement. The study has been carried out for the Rayleigh number in the range 104 ≤ Ra ≤ 107, and for solid volume fraction 0 ≤ φ ≤ 0.05. In order to investigate the effect of heat source location, three different placement configurations of heat sources are considered. The effects of both Rayleigh numbers and heat source locations on the streamlines, isotherms, Nusselt number are investigated. The results indicate that the flow field and temperature distributions inside the cavity are strongly dependent on the Rayleigh numbers and the position of the heat sources. The results also indicate that the Nusselt number is an increasing function of the Rayleigh number, the distance between two heat sources, and distance from the wall. In addition it is observed that the average Nusselt number increases linearly with the increase in the solid volume fraction of nanoparticles. 相似文献
128.
Human peripheral blood mononuclear cell in vitro system to test the efficacy of food bioactive compounds: Effects of polyunsaturated fatty acids and their relation with BMI
下载免费PDF全文
![点击此处可从《Molecular nutrition & food research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
129.
René J. Hernández-Bautista Francisco J. Alarcón-Aguilar María Del C. Escobar-Villanueva Julio C. Almanza-Pérez Héctor Merino-Aguilar Mina Konigsberg Fainstein Norma E. López-Diazguerrero 《International journal of molecular sciences》2014,15(7):11473-11494
Obesity, from children to the elderly, has increased in the world at an alarming rate over the past three decades, implying long-term detrimental consequences for individual’s health. Obesity and aging are known to be risk factors for metabolic disorder development, insulin resistance and inflammation, but their relationship is not fully understood. Prevention and appropriate therapies for metabolic disorders and physical disabilities in older adults have become a major public health challenge. Hence, the aim of this study was to evaluate inflammation markers, biochemical parameters and glucose homeostasis during the obese-aging process, to understand the relationship between obesity and health span during the lifetime. In order to do this, the monosodium glutamate (MSG) obesity mice model was used, and data were evaluated at 4, 8, 12, 16 and 20 months in both female and male mice. Our results showed that obesity was a major factor contributing to premature alterations in MSG-treated mice metabolism; however, at older ages, obesity effects were attenuated and MSG-mice became more similar to normal mice. At a younger age (four months old), the Lee index, triglycerides, total cholesterol, TNF-α and transaminases levels increased; while adiponectin decreased and glucose tolerance and insulin sensitivity levels were remarkably altered. However, from 16 months old-on, the Lee index and TNF-α levels diminished significantly, while adiponectin increased, and glucose and insulin homeostasis was recovered. In summary, MSG-treated obese mice showed metabolic changes and differential susceptibility by gender throughout life and during the aging process. Understanding metabolic differences between genders during the lifespan will allow the discovery of specific preventive treatment strategies for chronic diseases and functional decline. 相似文献
130.
目的评价综合康复治疗对老年股骨近端骨折患者术后疗效的影响。方法 90例采用手术治疗的75岁以上老年股骨近端骨折患者,排除病理性骨折、双侧股骨骨折或以前对侧股骨骨折、痴呆、认知障碍。根据术后有无系统的康复治疗分为康复组46例、对照组44例。康复组术后采取早期系统康复治疗和训练,对照组术后常规康复治疗。比较2组疗效及并发症发生率。结果术后随访6个月,康复组术后并发症发生率为16%,明显少于对照组(36%)(P〈0.05);康复组优良率为89%,高于对照组(68%)(P〈0.05)。结论手术治疗老年股骨近端骨折能获得可靠的固定,系统的康复训练是保证疗效的重要措施,有助于加快患者术后功能康复,提高生活质量。 相似文献