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   5792篇
  免费   239篇
  国内免费   3篇
电工技术   80篇
综合类   26篇
化学工业   1064篇
金属工艺   75篇
机械仪表   79篇
建筑科学   456篇
矿业工程   7篇
能源动力   142篇
轻工业   997篇
水利工程   49篇
石油天然气   11篇
武器工业   1篇
无线电   328篇
一般工业技术   745篇
冶金工业   1310篇
原子能技术   56篇
自动化技术   608篇
  2023年   42篇
  2022年   105篇
  2021年   208篇
  2020年   65篇
  2019年   89篇
  2018年   110篇
  2017年   109篇
  2016年   143篇
  2015年   122篇
  2014年   149篇
  2013年   245篇
  2012年   254篇
  2011年   332篇
  2010年   232篇
  2009年   218篇
  2008年   233篇
  2007年   360篇
  2006年   156篇
  2005年   153篇
  2004年   143篇
  2003年   136篇
  2002年   130篇
  2001年   80篇
  2000年   92篇
  1999年   108篇
  1998年   386篇
  1997年   231篇
  1996年   153篇
  1995年   135篇
  1994年   92篇
  1993年   91篇
  1992年   39篇
  1991年   50篇
  1990年   48篇
  1989年   50篇
  1988年   40篇
  1987年   34篇
  1986年   32篇
  1985年   39篇
  1984年   28篇
  1983年   25篇
  1982年   31篇
  1981年   33篇
  1980年   30篇
  1979年   40篇
  1978年   20篇
  1977年   37篇
  1976年   55篇
  1973年   27篇
  1969年   19篇
排序方式: 共有6034条查询结果,搜索用时 687 毫秒
51.
Thin discontinuous (4 and 35 nm thick) platinum films were used as the gate metal of metal-oxide-semiconductor capacitors. It was observed that the metal film acts as a gas permeable structure in electrolyte solutions when the surface was hydrophobic and sufficiently rough. The probable explanation to this is that the electrolyte does not penetrate into the voids of the metal film. The geometry of the surface was investigated by transsion electron microscopy and profilometer measurements. Surfaces with different contact angles were studied in order to determine whether the electrolyte penetrates into the voids in the platinum film when the surface is sufficiently hydrophilic.  相似文献   
52.
We performed BAEP study to evaluate acoustic nerve involvement in 102 patients affected by peripheral neuropathies of different etiology, predominantly hereditary and inflammatory acquired neuropathies. Prolonged latency of early waves, indicative of slowing in VIII nerve conduction, was found in a high percentage of cases. Abnormalities were far more frequent (44% vs 14%) and severe in patients with demyelinating rather than axonal neuropathy. Among demyelinating neuropathy, the most severe latency delay was found in Hereditary Motor and Sensory Neuropathy type III. The pattern of acoustic nerve involvement differed slightly between Hereditary Motor and Sensory Neuropathy type I and acquired inflammatory demyelinating polyradiculoneuropathy, perhaps reflecting different pathogenetic mechanisms and different sites of VIII nerve demyelination.  相似文献   
53.
54.
Attempts to model the degradation of polymer composites have been restricted to modelling the effects of selected degradation mechanisms. No comprehensive model has yet been accepted to predict the effect of the natural environment on the strength of polymer composites. From a review of available literature, it appears that the matrix of a polymer composite is most affected by exposure to the natural environment. Further, the damage appears to progress from the surface into the interior of the laminate. An approach has been developed to determine the properties of the damaged layer and combine the properties of the damaged and undamaged layer to obtain bulk material properties of the laminate.  相似文献   
55.
Far-infrared magnetotransmission measurements have been performed on MBE-grown HgTe and CdTe epilayers. The results on the HgTe samples can be understood by the standard Pidgeon-Brown model for bulk HgTe. For the CdTe layers, transitions were only observed under illumination by visible light. The spectra are dominated by the 1s→2p transition of the shallow hydrogen-like impurity. These transitions are persistent with a life time of the order of magnitude of one second.  相似文献   
56.
Behaviors and emotions during specific visits may reveal the interpersonal processes of mother-daughter ties, yet most research uses global assessments of these ties. Forty-eight mother-daughter pairs participated in audiotaped conversations and completed surveys. All mothers were over age 70 and in good health. Daughters tended to take a central role in structuring the conversations. Conversations were characterized by high levels of felt and expressed positive emotions and behaviors for mothers and daughters. Nevertheless, mothers reported more positive and fewer negative emotions, whereas daughters expressed more positive behaviors than did mothers. Mothers' positive feelings and behaviors were associated with daughters'. Finally, mothers' and daughters' emotions and behaviors were associated with their destructive responses to being upset with each other, providing support for the ambivalence perspective of parent-offspring relationships. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
57.
The removal of a mixture of painting solvents from waste air using a biofiltration process was evaluated in this project. The pollutants removed included hydrophobic (aromatic hydrocarbons) and hydrophilic (water soluble ketones and esters) compounds. A trickle bed reactor with a defined immobilized mixed culture on polyethylene Pall rings was utilized in this biodegradation study. The removal efficiencies (RE) of the individual groups of pollutants during loading experiments were determined. An increase of the aromatic hydrocarbons loading resulted in a drop of their REAROM with no effect on the RE value of ketones. The overloading of ketones caused a rapid drop in REAROM and a small drop in REKET. To achieve a restoration of the biocatalyst degradation properties after the increase in loading, an addition of phosphate to the aqueous medium was implemented which successfully restored the removal efficiency.  相似文献   
58.
Healthy Aims is a 23- million, four-year project, funded under the EU's information society technology sixth framework program to develop intelligent medical implants and diagnostic systems (www.healthyaims.org). The project has 25 partners from 10 countries, including commercial, clinical, and research groups. This consortium represents a combination of disciplines to design and fabricate new medical devices and components as well as to test them in laboratories and subsequent clinical trials. The project focuses on medical implants for nerve stimulation and diagnostic equipment based on strain-gauge technology.  相似文献   
59.
Fifty-two case-hardened, severely self-abusive and aggressive autistic and retarded students, living in six different community residences, were trained to exit their residences, without the presence or assistance of staff, when a fire alarm sounded at night. On a pretest, prior to an 11-week period of intensive environmental and behavioral interventions, only 25% of the students exited within 2 1/2 minutes and independent of staff assistance. At posttest, 100% exited successfully, in a mean evacuation time of 60 seconds. The study was conducted at the Behavior Research Institute (BRI).  相似文献   
60.
The electron paramagnetic resonance (EPR) of Mn2+ in Cd1?x Mn x Te was examined at low temperatures and high magnetic fields with the Mn concentration ranging fromx=0.01 tox=0.65. A far infrared laser was used as a radiation source. The structure of the resonance is strongly influenced by electromagnetic propagation effects. By variation of the sample thickness it was clearly shown that the satellite structures besides the main EPR peak, formerly explained as originating from transitions in the Mn2+ pair energy level scheme, are solely due to interference effects.  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