全文获取类型
收费全文 | 2213篇 |
免费 | 78篇 |
国内免费 | 12篇 |
学科分类
工业技术 | 2303篇 |
出版年
2021年 | 37篇 |
2020年 | 25篇 |
2019年 | 25篇 |
2018年 | 33篇 |
2017年 | 35篇 |
2016年 | 32篇 |
2015年 | 34篇 |
2014年 | 48篇 |
2013年 | 222篇 |
2012年 | 71篇 |
2011年 | 82篇 |
2010年 | 90篇 |
2009年 | 83篇 |
2008年 | 94篇 |
2007年 | 76篇 |
2006年 | 56篇 |
2005年 | 62篇 |
2004年 | 50篇 |
2003年 | 47篇 |
2002年 | 40篇 |
2001年 | 32篇 |
2000年 | 18篇 |
1999年 | 26篇 |
1998年 | 70篇 |
1997年 | 45篇 |
1996年 | 47篇 |
1995年 | 50篇 |
1994年 | 38篇 |
1993年 | 43篇 |
1992年 | 28篇 |
1991年 | 28篇 |
1990年 | 36篇 |
1988年 | 21篇 |
1987年 | 27篇 |
1986年 | 32篇 |
1985年 | 21篇 |
1984年 | 31篇 |
1983年 | 26篇 |
1982年 | 28篇 |
1981年 | 33篇 |
1980年 | 22篇 |
1979年 | 20篇 |
1978年 | 19篇 |
1977年 | 23篇 |
1976年 | 19篇 |
1975年 | 34篇 |
1974年 | 19篇 |
1973年 | 18篇 |
1971年 | 17篇 |
1966年 | 18篇 |
排序方式: 共有2303条查询结果,搜索用时 223 毫秒
41.
Mahdiar Valefi Matthijn de Rooij Dirk J. Schipper Louis Winnubst 《Journal of the European Ceramic Society》2012,32(10):2235-2242
Results of wear tests using an alumina ball sliding against 5 wt% copper oxide doped tetragonal zirconia polycrystalline (CuO-TZP) ceramics are reported as a function of temperature up to 700 °C. The specific wear rate and friction coefficient are strongly dependent on temperature. Below a critical temperature (T < 600 °C), CuO-TZP showed a high coefficient of friction as well as a high wear rate. This was ascribed to the formation of a rough surface, caused by brittle fracture and abrasive wear, based on observations by scanning electron microscopy (SEM), laser scanning microscopy (LSM) and X-ray photoelectron spectroscopy (XPS). However, above 600 °C a self-healing layer is formed at the interface and results in low friction and wear. The mechanism of layer formation and restoration is discussed and rationalized by onset of plastic deformation caused by a reduction reaction of CuO to Cu2O at high temperatures. 相似文献
42.
43.
Qian Fang Dingli Zhang Louis Ngai Yuen Wong 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》2011,26(6):750-763
Ground surface settlement induced by urban subway construction using shallow tunnelling method is inevitable and it may cause a series of negative impact to existing nearby structures and utilities. In order to guarantee environmental safety, a risk management methodology which aims at process control for ground settlement and existing nearby structures is proposed. It includes 5-stage technology-based steps: survey of existing conditions, designing control standards for key risk factors, analyzing environmental response under tunnel construction and designing process control standards, monitoring and taking proper process control measures during construction, and risk reassessment after construction. This methodology was put into practice in the Huangzhuang subway station construction which is the largest cross interchange subway station construction using shallow tunnelling method in China. According to site survey, nearby pipelines and existing buildings were determined to be the key risk factors. The risk control standards for nearby pipelines and existing buildings were made according to available standards in China and related literatures. Design of process control standards for ground surface settlement was assisted by numerical simulation, which aimed at controlling the key risk factors. During construction, monitoring was adopted for the nearby pipelines, existing buildings and ground surface. After the four drifts excavation of the double-deck part of Line 4, a series of risk control measures, which included treatment of the unfavorable geological bodies, installation of roof pipes, compensation grouting, full-face grouting and some other control measures, were taken. Due to these risk control measures, ground surface settlements, except at two measuring points of Line 4, were successfully controlled under the given process control standards for both Line 4 and Line 10. All the pipelines and buildings were under their normal service state during tunnel construction. The maximum deflection for the 6 pipelines above the station was controlled to be within 2 mm/m and the maximum settlement of all the monitoring points for the pipelines was less than 30 mm. For the four important existing buildings in close vicinity, the maximum deflection was less than 1 mm/m; the maximum settlement value was 6.8 mm and the maximum uplift value was 3.0 mm. The risk control system was shown to be effective in ensuring environment safety, structure safety and construction safety. These safety control methods, the methodology of designing these control standards and the measures taken in the construction can serve as a practical reference for other similar projects. 相似文献
44.
45.
Nebulized Gadolinium‐Based Nanoparticles: A Theranostic Approach for Lung Tumor Imaging and Radiosensitization 下载免费PDF全文
Sandrine Dufort Andrea Bianchi Maxime Henry François Lux Géraldine Le Duc Véronique Josserand Cédric Louis Pascal Perriat Yannick Crémillieux Olivier Tillement Jean‐Luc Coll 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(2):215-221
Lung cancer is the most common and most fatal cancer worldwide. Thus, improving early diagnosis and therapy is necessary. Previously, gadolinium‐based ultra‐small rigid platforms (USRPs) were developed to serve as multimodal imaging probes and as radiosensitizing agents. In addition, it was demonstrated that USRPs can be detected in the lungs using ultrashort echo‐time magnetic resonance imaging (UTE‐MRI) and fluorescence imaging after intrapulmonary administration in healthy animals. The goal of the present study is to evaluate their theranostic properties in mice with bioluminescent orthotopic lung cancer, after intrapulmonary nebulization or conventional intravenous administration. It is found that lung tumors can be detected non‐invasively using fluorescence tomography or UTE‐MRI after nebulization of USRPs, and this is confirmed by histological analysis of the lung sections. The deposition of USRPs around the tumor nodules is sufficient to generate a radiosensitizing effect when the mice are subjected to a single dose of 10 Gy conventional radiation one day after inhalation (mean survival time of 112 days versus 77 days for irradiated mice without USRPs treatment). No apparent systemic toxicity or induction of inflammation is observed. These results demonstrate the theranostic properties of USRPs for the multimodal detection of lung tumors and improved radiotherapy after nebulization. 相似文献
46.
An X‐FEM‐based numerical–asymptotic expansion for simulating a Stokes flow near a sharp corner 下载免费PDF全文
Louis C. Foucard Franck J. Vernerey 《International journal for numerical methods in engineering》2015,102(2):79-98
A numerical technique that is based on the integration of the asymptotic solution in the numerical framework for computing the local singular behavior of Stokes flow near a sharp corner is presented. Moffat's asymptotic solution is used, and special enriched shape functions are developed and integrated in the extended finite element method (X‐FEM) framework to solve the Navier–Stokes equations. The no‐slip boundary condition on the walls of the corner is enforced via the use of Lagrange multipliers. Flows around corners with different angles are simulated, and the results are compared with both those of the known analytic solution and the X‐FEM with no special enrichment near the corner. The results of the present technique are shown to greatly reduce the error made in computing the pressure and velocity fields near a corner tip without the need for mesh refinement near the corner. The method is then applied to the estimation of the permeability of a network of fibers, where it is shown that the local small‐scale pressure singularities have a large impact on the large‐scale network permeability. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
47.
Coubard Olivier A.; Ferrufino Lena; Boura Marine; Gripon Alice; Renaud Mélanie; Bherer Louis 《Canadian Metallurgical Quarterly》2011,25(3):353
Objective: Attentional control, the ability to maintain goal-directedness in the face of distraction, has been shown to decline in normal aging (NA) and Alzheimer's disease (AD), yet the nature and extent of deficits is under debate. This study investigated attentional control in NA and AD compared to healthy young adults in several tasks such as setting, suppressing, switching, and preparing attention. Method: Fifty-two participants (17 AD, 17 NA, and 18 young participants) underwent the Tower of London, the Zoo map test, the Stroop test, letter verbal fluency, a computerized version of the Rule shift cards tests, the Trail making test, the Plus-minus test, and a reaction time task with variable preparatory intervals. Results: Analyses of variance showed that NA as compared to young participants were impaired in the Tower of London, the Stroop test, and the Rule shift cards tests. AD as compared to NA participants were impaired in all tests except the Stroop test. Principal component analysis in young adults confirmed the modularity of attentional tasks, which was reduced in NA and AD participants. Principal component analysis in all populations showed a decline of attentional control with NA and AD regardless of the tasks, with an increase in between-participants variability only between young and NA participants. Conclusions: Attentional control dysfunction is different in NA and AD: NA affects suppressing attention, switching attention for unpredictable but not predictable events, and preparing attention for unpredictable events, whereas AD affects setting, suppressing, switching, and preparing attention with less specificity. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
48.
Tagro S. Guehi Adjéhi T. Dadie Kouadio P. B. Koffi Soumaïla Dabonne Louis Ban‐Koffi Kra D. Kedjebo Gnopo J. Nemlin 《International Journal of Food Science & Technology》2010,45(12):2508-2514
This study aims to compare the effect of three cocoa fermentation methods and their duration on raw cocoa quality. Results showed a decrease in percentage of physical quality defects on fermentation method. Cocoa fermented for 4 days presented higher percentage of purple beans reached 45% and about 10% of slaty beans than cocoa fermented for 6 days whatever the process. Fermentation duration did not influence the mouldy beans that were around 1%. Formation of brown beans increased from 16% to 50% depending on the fermentation duration and process. Using wooden boxes allowed higher percentage of 77%–90% brown beans than others materials. Acidity of cocoa decreased on fermentation duration but beans treated in boxes were significantly (P = 0.05) acidic from 1.40 and 3.07 meq of NaOH g?1. Fungal population did not vary in number depending both on the duration and the fermentation method with rates that ranged from 3.32 × 107 to 8.63 × 107 CFU g?1. 相似文献
49.
Jit Biswas Andrei Tolstikov Maniyeri Jayachandran Victor Foo Aung Aung Phyo Wai Clifton Phua Weimin Huang Louis Shue Kavitha Gopalakrishnan Jer-En Lee Philip Yap 《电信纪事》2010,65(9-10):505-521
Monitoring and timely intervention are extremely important in the continuous management of health and wellness among all segments of the population, but particularly among those with mild dementia. In relation to this, we prescribe three design principles for the construction of services and applications. These are ambient intelligence, service continuity, and micro-context. In this paper, we provide three exemplars from our research and development activities that illustrate the use of these design principles in the construction of services and applications. All the applications are drawn from the field of care for mild dementia patients in their living quarters. 相似文献
50.