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   33383篇
  免费   929篇
  国内免费   66篇
电工技术   372篇
综合类   35篇
化学工业   6824篇
金属工艺   868篇
机械仪表   625篇
建筑科学   1861篇
矿业工程   247篇
能源动力   1017篇
轻工业   2780篇
水利工程   341篇
石油天然气   208篇
武器工业   2篇
无线电   2181篇
一般工业技术   5244篇
冶金工业   6786篇
原子能技术   325篇
自动化技术   4662篇
  2022年   199篇
  2021年   387篇
  2020年   334篇
  2019年   402篇
  2018年   495篇
  2017年   513篇
  2016年   524篇
  2015年   467篇
  2014年   746篇
  2013年   2146篇
  2012年   1249篇
  2011年   1597篇
  2010年   1176篇
  2009年   1274篇
  2008年   1451篇
  2007年   1480篇
  2006年   1264篇
  2005年   1183篇
  2004年   1058篇
  2003年   1034篇
  2002年   1043篇
  2001年   651篇
  2000年   623篇
  1999年   584篇
  1998年   646篇
  1997年   526篇
  1996年   631篇
  1995年   554篇
  1994年   546篇
  1993年   543篇
  1992年   490篇
  1991年   322篇
  1990年   439篇
  1989年   427篇
  1988年   381篇
  1987年   428篇
  1986年   384篇
  1985年   518篇
  1984年   491篇
  1983年   443篇
  1982年   466篇
  1981年   449篇
  1980年   356篇
  1979年   365篇
  1978年   331篇
  1977年   308篇
  1976年   271篇
  1975年   320篇
  1974年   243篇
  1973年   279篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A series of co-engineered macrolide–mannitol particles were successfully prepared using azithromycin (AZ) as a model drug. The formulation was designed to target local inflammation and bacterial colonization, via the macrolide component, while the mannitol acted as mucolytic and taste-masking agent. The engineered particles were evaluated in terms of their physico-chemical properties and aerosol performance when delivered via a novel high-payload dry powder Orbital? inhaler device that operates via multiple inhalation manoeuvres. All formulations prepared were of suitable size for inhalation drug delivery and contained a mixture of amorphous AZ with crystalline mannitol. A co-spray dried formulation containing 200?mg of 50:50?w/w AZ: mannitol had 57.6%?±?7.6% delivery efficiency with a fine particle fraction (≤6.8?µm) of the emitted aerosol cloud being 80.4%?±?1.1%, with minimal throat deposition (5.3?±?0.9%). Subsequently, it can be concluded that the use of this device in combination with the co-engineered macrolide–mannitol therapy may provide a means of treating bronchiectasis.  相似文献   
992.
Imaging techniques based on neutron beams are rapidly developing and have become versatile non-destructive analyzing tools in many research fields. Due to their intrinsic properties, neutrons differ strongly from electrons, protons or X-rays in terms of their interaction with matter: they penetrate deeply into most common metallic materials while they have a high sensitivity to light elements such as hydrogen, hydrogenous substances, or lithium. This makes neutrons perfectly suited probes for research on materials that are used for energy storage and conversion, e.g., batteries, hydrogen storage, fuel cells, etc. Moreover, their wave properties can be exploited to perform diffraction, phase-contrast and dark-field imaging experiments. Their magnetic moment allows for resolving magnetic properties in bulk samples. This review will focus on recent applications of neutron imaging techniques in both materials research and fundamental science illustrated by examples selected from different areas.  相似文献   
993.
994.
995.
996.
Abstract

Vitamin E is a lipid soluble vitamin comprising of eight natural isoforms, namely, α, β, δ, γ isoforms of tocopherol and α, β, δ, γ isoforms of tocotrienol. Many studies have been performed to elucidate its role in cancer. Until last decade, major focus was on alpha tocopherol and its anticancer effects. However, major clinical trials using alpha-tocopherol like SELECT trial and ATBC trial did not yield meaningful results. Hence there was a shift of focus to gamma-tocopherol, delta-tocopherol and tocotrienol. Unlike alpha-tocopherol, gamma-tocopherol and delta-tocopherol can scavenge reactive nitrogen species in addition to reactive oxygen species. Antiangiogenic effect, inhibition of HMG CoA reductase enzyme and inhibition of NF-κB pathway make the anti-cancer effects of tocotrienols unique compared to other vitamin E isoforms. Preclinical research on non-alpha tocopherol isoforms of vitamin E showed promising data on their anticancer effects. In this review, we deal with the current understanding on the potential mechanisms involved in the anticancer effects of vitamin E and the controversies in this field over last three decades. We also highlight the need to conduct further research on the anticancer effects of non-alpha-tocopherol isoforms in larger population and clinical setting.  相似文献   
997.
The Nightingallery project encouraged participants to converse, sing, and perform with a musically responsive animatronic bird, playfully interacting with the character while members of the public could look on and observe. We used Nightingallery to frame an HCI investigation into how people would engage with one another when confronted with unfamiliar technologies in conspicuously public, social spaces. Structuring performances as improvisational street theatre, we styled our method of exhibiting the bird character. We cast ourselves in supporting roles as carnival barkers and minders of the bird, presenting him as if he were a fantastical creature in a fairground sideshow display, allowing him the agency to shape and maintain dialogues with participants, and positioning him as the focal character upon which the encounter was centred. We explored how the anthropomorphic nature of the bird itself, along with the cultural connotations associated with the carnival/sideshow tradition helped signpost and entice participants through the trajectory of their encounters with the exhibit. Situating ourselves as secondary characters within the narrative defining the performance/use context, our methods of mediation, observation, and evaluation were integrated into the performance frame. In this paper, we explore recent HCI theories in mixed reality performance to reflect upon how genre-based cultural connotations can be used to frame trajectories of experience, and how manipulation of roles and agency in participatory performance can facilitate HCI investigation of social encounters with playful technologies.  相似文献   
998.
999.
1000.
The amount of deception taking place via electronic text-based communication is increasing. Research has sought to automatically detect deception by analyzing the text from the communicator. However, the deceptive intent of the communication partner is being ignored. We compare the text from subjects who are trying to deceive each other, subjects trying to deceive truth tellers, subjects telling the truth to truth tellers, and subjects telling the truth to deceivers. We hypothesize that despite the intent of the partner, deceitful text will cluster closest to deceitful text. We cluster each of the four conditions using the text content. The cluster algorithm placed subjects trying to deceive each other closest to subjects telling the truth to each other. In this analysis, the language that led subjects to choose the same outcomes had a stronger effect than the language tied to being deceitful or truthful.  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