首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3643篇
  免费   236篇
  国内免费   2篇
电工技术   18篇
综合类   1篇
化学工业   734篇
金属工艺   16篇
机械仪表   30篇
建筑科学   152篇
矿业工程   4篇
能源动力   56篇
轻工业   442篇
水利工程   45篇
石油天然气   8篇
无线电   186篇
一般工业技术   600篇
冶金工业   1212篇
原子能技术   1篇
自动化技术   376篇
  2024年   8篇
  2023年   26篇
  2022年   60篇
  2021年   97篇
  2020年   65篇
  2019年   60篇
  2018年   89篇
  2017年   89篇
  2016年   92篇
  2015年   96篇
  2014年   114篇
  2013年   207篇
  2012年   184篇
  2011年   327篇
  2010年   243篇
  2009年   215篇
  2008年   273篇
  2007年   243篇
  2006年   209篇
  2005年   175篇
  2004年   137篇
  2003年   124篇
  2002年   121篇
  2001年   81篇
  2000年   71篇
  1999年   65篇
  1998年   47篇
  1997年   60篇
  1996年   43篇
  1995年   43篇
  1994年   28篇
  1993年   29篇
  1992年   20篇
  1991年   7篇
  1990年   19篇
  1989年   20篇
  1988年   12篇
  1987年   13篇
  1986年   11篇
  1985年   13篇
  1984年   10篇
  1983年   10篇
  1981年   6篇
  1980年   3篇
  1979年   2篇
  1978年   2篇
  1977年   2篇
  1975年   5篇
  1968年   1篇
  1966年   1篇
排序方式: 共有3881条查询结果,搜索用时 31 毫秒
131.
132.
133.
134.
135.
136.
A statistical quality control chart is widely recognized as a potentially powerful tool that is frequently used in many manufacturing and service industries to monitor the quality of the product or manufacturing processes. In this paper, we propose new synthetic control charts for monitoring the process mean and the process dispersion. The proposed synthetic charts are based on ranked set sampling (RSS), median RSS (MRSS), and ordered RSS (ORSS) schemes, named synthetic‐RSS, synthetic‐MRSS, and synthetic‐ORSS charts, respectively. Average run lengths are used to evaluate the performances of the control charts. It is found that the synthetic‐RSS and synthetic‐MRSS mean charts perform uniformly better than the Shewhart mean chart based on simple random sampling (Shewhart‐SRS), synthetic‐SRS, double sampling‐SRS, Shewhart‐RSS, and Shewhart‐MRSS mean charts. The proposed synthetic charts generally outperform the exponentially weighted moving average (EWMA) chart based on SRS in the detection of large mean shifts. We also compare the performance of the synthetic‐ORSS dispersion chart with the existing powerful dispersion charts. It turns out that the synthetic‐ORSS chart also performs uniformly better than the Shewhart‐R, Shewhart‐S, synthetic‐R, synthetic‐S, synthetic‐D, cumulative sum (CUSUM) ln S2, CUSUM‐R, CUSUM‐S, EWMA‐ln S2, and change point CUSUM charts for detecting increases in the process dispersion. A similar trend is observed when the proposed synthetic charts are constructed under imperfect RSS schemes. Illustrative examples are used to demonstrate the implementation of the proposed synthetic charts. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
137.
Abstract

Context: Aerosol delivery to animals in preclinical settings has historically been very challenging, requiring the use of techniques, such as intratracheal instillation and dry powder insufflation, that are somewhat invasive, inefficient and not representative of clinical inhalation.

Objective: The objective of this work is to develop a system to deliver dry powder to dogs in an efficient and effective manner for the study of new anti-migraine compounds in development.

Materials and methods: The new device uses a metered aliquot of a dry gas to force dry powder drug from a pre-filled HPMC capsule into an AeroChamber® spacer for subsequent inhalation by the animal.

Results: The delivery of two invesigational migraine drugs via the new device was assessed in vitro using abbreviated Andersen cascade impaction and showed the device is capable of generating a reproducible delivered dose of up to ~68% with more than 50% of the dose in the respirable range. In vivo studies have also been performed showing that this device effectively delivered the migraine drugs to spontaneously breathing dogs using a proprietary validated dog inhalation model.

Discussion: Results confirmed that the air pressurized capsule device (APCD) was effective in delivering the APIs to lungs of the animals. The in vivo data verified the advantages of inhaled delivery over oral delivery for this class of drugs and were used to establish the cardiopulmonary and respiratory side effect liability profile for these compounds.

Conclusions: This work has demonstrated the utility of this device for quick and accurate screening of prospective drug candidates, representing a significant improvement in ease of use and reprodicibility over current delivery methods.  相似文献   
138.
Maximum exponentially weighted moving average (MaxEWMA) control charts have gained considerable attention for detecting changes in both process mean and process variability. In this paper, we propose an improved MaxEWMA control charts based on ordered ranked set sampling (ORSS) and ordered imperfect ranked set sampling (OIRSS) schemes for simultaneous detection of both increases and decreases in the process mean and/or variability, named MaxEWMA‐ORSS and MaxEWMA‐OIRSS control charts. These MaxEWMA control charts are based on the best linear unbiased estimators of location and scale parameters obtained under ORSS and OIRSS methods. Extensive Monte Carlo simulations have been used to estimate the average run length and standard deviation of run length of the proposed MaxEWMA control charts. These control charts are compared with their counterparts based on simple random sampling (SRS), that is, MaxEWMA‐SRS and MaxGWMA‐SRS control charts. The proposed MaxEWMA‐ORSS and MaxEWMA‐OIRSS control charts are able to perform better than the MaxEWMA‐SRS and MaxGWMA‐SRS control charts for detecting shifts in the process mean and dispersion. An application to real data is provided to illustrate the implementation of the proposed MaxEWMA control charts. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
139.
Cultural landscapes can often be identified by the presence of sacred trees which have been retained and can be recognised as distinctive veteran trees. The characteristics of these trees such as huge size and longevity give them an enduring presence in the landscape, while their conceptualisation as the ‘domesticated’ wild, transform them into symbols of spirituality and local history. In Zagori, NW Greece, trees gain sanctity by virtue of proximity or connection with sacred sites often associated with churches. In these sites, trees can grow into natural shapes as a result of strong taboos, which prevent use for private needs. There is an association between tree species and the nature of the sacred site: broadleaved oaks and maples are associated with outlying churches; plane trees are located in central squares, next to the church and provide a focal point for community life, while in cemeteries native evergreens are nowadays replaced by planted conifers. In the present day local communities appreciate sacred trees as living elements of their collective memory and local history.  相似文献   
140.
A post-occupancy evaluation (POE) of 12 green and 12 conventional office buildings across Canada and the northern United States was conducted. Occupants (N = 2545) completed an online questionnaire related to environmental satisfaction, job satisfaction and organizational commitment, health and well-being, environmental attitudes, and commuting. In each building on-site physical measurements at a sample of workstations (N= 974) were taken, including: thermal conditions, air quality, acoustics, lighting, workstation size, ceiling height, window access and shading, and surface finishes. Green buildings exhibited superior performance compared with similar conventional buildings. Better outcomes included: environmental satisfaction, satisfaction with thermal conditions, satisfaction with the view to the outside, aesthetic appearance, less disturbance from heating, ventilation and air-conditioning (HVAC) noise, workplace image, night-time sleep quality, mood, physical symptoms, and reduced number of airborne particulates. A variety of physical features led to improved occupant outcomes across all buildings, including: conditions associated with speech privacy, lower background noise levels, higher light levels, greater access to windows, conditions associated with thermal comfort, and fewer airborne particulates. Green building rating systems might benefit from further attention in several areas, including: credits related to acoustic performance, a greater focus on reducing airborne particulates, enhanced support for the interdisciplinary design process and development of POE protocols.

Il a été mené une évaluation après occupation (POE) de 12 immeubles de bureaux verts et 12 immeubles de bureaux classiques répartis à travers le Canada et le nord des Etats-Unis. Les occupants (N?=?2545) ont rempli un questionnaire en ligne portant sur la satisfaction environnementale, la satisfaction au travail et l'implication organisationnelle, la santé et le bien-être, les attitudes environnementales, et les trajets réguliers. Dans chaque immeuble, des mesures physiques in situ sur un échantillon de postes de travail (N?=?974) ont été effectuées, comprenant : les conditions thermiques, la qualité de l'air, l'acoustique, l'éclairage, la taille des postes de travail, la hauteur de plafond, l'accès aux fenêtres et leur occultation, et les finitions de surface. Les bâtiments verts ont affiché des performances supérieures par rapport aux bâtiments classiques similaires. De meilleurs résultats ont été obtenus concernant la satisfaction environnementale, la satisfaction à l'égard des conditions thermiques, la satisfaction à l'égard de la vue sur l'extérieur, l'aspect esthétique, la diminution des perturbations liées aux bruits provenant du chauffage, de la ventilation et de la climatisation (CVC), l'image du lieu de travail, la qualité du sommeil nocturne, l'humeur, les symptômes physiques, et la réduction du nombre de particules en suspension dans l'air. Différentes caractéristiques physiques ont conduit à une amélioration des résultats pour les occupants dans tous les immeubles, concernant notamment les conditions liées à la confidentialité des conversations, les niveaux inférieurs de bruit de fond, les niveaux de luminosité plus élevés, l'accès accru aux fenêtres, les conditions associées au confort thermique, et le nombre moindre de particules en suspension dans l'air. Les systèmes de notation des bâtiments verts pourraient bénéficier d'une plus grande attention apportée à plusieurs domaines, s'agissant en particulier des crédits relatifs aux performances acoustiques, d'un accent accru sur la réduction des particules en suspension dans l'air, d'un soutien renforcé en faveur du processus de conception interdisciplinaire et du développement de protocoles POE.

Mots clés: performances des bâtiments, bilan environnemental, bâtiments verts, environnement intérieur, Leadership in Energy and Environmental Design (LEED), satisfaction des occupants, évaluation après occupation  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号