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   396篇
  免费   22篇
化学工业   111篇
金属工艺   3篇
机械仪表   3篇
建筑科学   30篇
能源动力   8篇
轻工业   68篇
水利工程   1篇
无线电   9篇
一般工业技术   56篇
冶金工业   59篇
自动化技术   70篇
  2023年   3篇
  2022年   9篇
  2021年   20篇
  2020年   10篇
  2019年   10篇
  2018年   8篇
  2017年   10篇
  2016年   11篇
  2015年   9篇
  2014年   20篇
  2013年   28篇
  2012年   19篇
  2011年   33篇
  2010年   16篇
  2009年   22篇
  2008年   18篇
  2007年   19篇
  2006年   15篇
  2005年   12篇
  2004年   9篇
  2003年   15篇
  2002年   6篇
  2001年   6篇
  2000年   7篇
  1999年   7篇
  1998年   7篇
  1997年   3篇
  1996年   5篇
  1995年   5篇
  1994年   4篇
  1993年   4篇
  1992年   5篇
  1990年   3篇
  1989年   2篇
  1988年   5篇
  1985年   5篇
  1982年   2篇
  1981年   1篇
  1980年   2篇
  1979年   3篇
  1978年   1篇
  1977年   3篇
  1976年   3篇
  1974年   1篇
  1970年   1篇
  1965年   2篇
  1964年   1篇
  1962年   1篇
  1960年   1篇
  1957年   1篇
排序方式: 共有418条查询结果,搜索用时 31 毫秒
111.
Proprotein convertase subtilin/kexin type 9 (PCSK9) is a protease secreted mainly by hepatocytes and in lesser quantities by intestines, pancreas, and vascular cells. Over the years, this protease has gained importance in the field of cardiovascular biology due to its regulatory action on the low-density lipoprotein receptor (LDLR). However, recently, it has also been shown that PCSK9 acts independent of LDLR to cause vascular inflammation and increase the severity of several cardiovascular disorders. We hypothesized that PCSK9 affects the expression of chemokine receptors, major mediators of inflammation, to influence cardiovascular health. However, using overexpression of PCSK9 in murine models in vivo and PCSK9 stimulation of myeloid and vascular cells in vitro did not reveal influences of PCSK9 on the expression of certain chemokine receptors that are known to be involved in the development and progression of atherosclerosis and vascular inflammation. Hence, we conclude that the inflammatory effects of PCSK9 are not associated with the here investigated chemokine receptors and additional research is required to elucidate which mechanisms mediate PCSK9 effects independent of LDLR.  相似文献   
112.
The aims of the present meta-analysis were to investigate the short- and long-term efficacy, multidimensional outcome, and treatment moderators of biofeedback as a behavioral treatment option for tension-type headache. A literature search identified 74 outcome studies, of which 53 were selected according to predefined inclusion criteria. Meta-analytic integration resulted in a significant medium-to-large effect size (d = 0.73; 95% confidence interval = 0.61, 0.84) that proved stable over an average follow-up phase of 15 months. Biofeedback was more effective than headache monitoring, placebo, and relaxation therapies. The strongest improvements resulted for frequency of headache episodes. Further significant effects were observed for muscle tension, self-efficacy, symptoms of anxiety, depression, and analgesic medication. Moderator analyses revealed biofeedback in combination with relaxation to be the most effective treatment modality; effects were particularly large in children and adolescents. In intention-to-treat and publication-bias analyses, the consistency of these findings was demonstrated. It is concluded that biofeedback constitutes an evidence-based treatment option for tension-type headache. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
113.
The storage stability of dark chocolate with nougat fillings is mainly limited by the formation of fat bloom, which arises because of the migration of nut oil from the filling to the outside of the chocolate shell where it leads to the formation of visible cocoa butter crystals. The triple-shot technique, which allows the simultaneous deposition of three viscous fluids, was applied for the laboratory-scale manufacture of pralines with a technofunctional barrier layer to prevent blooming. Base component of the barrier layer was palm kernel oil, pure or in combination with milk fat; micro-milled sugar or skim milk powder served as disperse phase. As compared to control experiments, the formation of fat bloom was significantly reduced for selected barrier layers because of the reduced transfer of nut oil to the outside of the praline shells. These results indicate that triple-shot depositing is a promising technique for the manufacture of filled chocolate with enhanced physical shelf life.  相似文献   
114.
Concerns about biodiversity and sustainability extend to many ecological systems, including large river systems that are highly modified by human activities. The Mississippi River is one such system that is currently regulated for navigational and flood control purposes, bears a large agricultural nutrient load, and has experienced rapid spread of the exotic zebra mussel, Dreissena polymorpha, since 1991. Human development of the extensive watershed system of the Mississippi River is ongoing and is expected to lead to further changes in river ecology. This study tested whether stable isotope compositions of the zebra mussel could help identify watershed and tributary loading of carbon (C), nitrogen (N), and sulphur (S) to the mainstem river. Zebra mussels were collected seasonally in the lower Mississippi River at Baton Rouge in 1997, and along most of the length of the river in a north–south transect from Minnesota to Louisiana during August 1998. Results showed substantial seasonal variations in C, N and S isotopic compositions of 2‰ or greater, but also that seasonal changes appeared regular and linked to changing watershed inputs and chemistry of the river water. Nitrate was the dominant N nutrient in the Mississippi River, but isotope analyses showed that food webs based on ammonium rather than nitrate were likely important for the zebra mussel. Results from the north–south transect followed expectations based on mixing of mainstem river water with tributaries that had different chemistries, so that local zones of influence were detectable in the combined CNS zebra mussel isotopes downstream of major tributary confluences for the Illinois, Missouri and Ohio Rivers. Overall, the study supports use of stable isotopes to help monitor watershed development and downstream effects on aquatic food webs. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   
115.
A new reflectometer-spectrophotometer has been designed and constructed using state-of-the-art technology to enhance optical properties of materials measurements over the ultraviolet, visible, and near-infrared (UV-Vis-NIR) wavelength range (200 nm to 2500 nm). The instrument, Spectral Tri-function Automated Reference Reflectometer (STARR), is capable of measuring specular and diffuse reflectance, bidirectional reflectance distribution function (BRDF) of diffuse samples, and both diffuse and non-diffuse transmittance. Samples up to 30 cm by 30 cm can be measured. The instrument and its characterization are described.  相似文献   
116.
礼尚往来作为一次成功外交的开始,在体现对两国情谊用心的同时,也暗示着一个民族的工艺水平。究竟国家元首“能够带出门”的国礼是什么呢?  相似文献   
117.
Humane care—which is an important design paradigm relevant for pervasive healthcare—means designing systems with care, keeping in mind both users and other stakeholders. Understanding human values is a key factor in creating any successful healthcare application and is essential to avoid dehumanizing and stigmatizing users. By considering human values, designers and developers can create pervasive healthcare applications that better fit users' needs and desires. The Designing with Care 09 workshop aimed to bring together researchers, designers, and practitioners to share their experiences with incorporating values into the design of pervasive healthcare systems and to help understand the sensitive issues involved in designing for healthcare. Based on the findings from the workshop, the present state of the art is discussed, and a research agenda is presented.  相似文献   
118.
The authors developed a terminology bridge for reflecting deeper meaning in play therapy by melding Carkhuff’s scale for measuring accurate empathy with the child-centered, Adlerian, and ecosystemic play therapy approaches. Designed to help university practicum and other supervisors facilitate beginning play therapists in the reflection of deeper meaning, this scale draws from historic core conditions in psychotherapy and correlates them to response skills of respected play therapy approaches in a 5-level scale. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
119.
Memory plasticity, or the ability to improve one's memory performance through instruction and training, is known to decline during adulthood. However, direct comparisons among middle childhood, adulthood, and old age are lacking. The authors examined memory plasticity in an age-comparative multisession training study. One hundred and eight participants ages 9-10, 11-12, 20-25, and 65-78 years learned and practiced an imagery-based mnemonic technique to encode and retrieve words by location cues. Individuals of all ages were able to acquire and optimize use of the technique. Older adults and children showed similar baseline performance and improvement through mnemonic instruction. However, in line with tenets from life-span psychology (P. B. Baltes, 1987), children profited more from mnemonic practice and reached higher levels of final performance than did older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
120.
As the use of computers increases, the cost of educating computer users rises. Therefore the need for extensive education of users should be avoided as much as possible. Instead computer systems should be adapted to the requirements and characteristics of computer users. Hereby the need to identify user characteristics arises. The less computer educated the users, the more their requirements of the systems will differ. Where user characteristics are difficult to change, it will be worthwhile to attend to user differences in the design of systems. The implications of user differences may vary depending upon the type of task to be performed. The present paper presents an analysis of different user characteristics and their possible interactions with different task requirements. Hereby some recommendations regarding the need to educate users or adapt systems to the user were derived.  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