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   267篇
  免费   23篇
化学工业   78篇
金属工艺   3篇
机械仪表   8篇
建筑科学   14篇
能源动力   6篇
轻工业   107篇
水利工程   1篇
无线电   5篇
一般工业技术   35篇
冶金工业   5篇
原子能技术   2篇
自动化技术   26篇
  2024年   1篇
  2023年   3篇
  2022年   13篇
  2021年   21篇
  2020年   13篇
  2019年   17篇
  2018年   10篇
  2017年   10篇
  2016年   15篇
  2015年   7篇
  2014年   19篇
  2013年   21篇
  2012年   16篇
  2011年   20篇
  2010年   15篇
  2009年   19篇
  2008年   9篇
  2007年   15篇
  2006年   11篇
  2005年   4篇
  2004年   5篇
  2003年   6篇
  2002年   7篇
  2000年   5篇
  1999年   3篇
  1998年   3篇
  1997年   1篇
  1996年   1篇
排序方式: 共有290条查询结果,搜索用时 15 毫秒
51.
Do nonselected lexical nodes activate their phonological information? Catalan-Spanish bilinguals were asked to name (a) pictures whose names are cognates, in the 2 languages (words that are phonologically similar in the 2 languages) and (b) pictures whose names are noncognates in the 2 languages. If nonselected lexical nodes are phonologically encoded, naming latencies should be shorter for cognate words, and because the cognate status of words is only meaningful for bilingual speakers, this difference should disappear when testing monolingual speakers. The results of Experiment 1 fully supported these predictions. In Experiment 2, the difference between cognate and noncognate words was larger when naming in the nondominant language than when naming in the dominant language. The results of the 2 experiments are interpreted as providing support to cascaded activation models of lexical access. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
52.
53.
The intramolecular palladium‐catalyzed reaction of N‐(iodoarylalkyl)pyrroles can be applied for the selective synthesis of medium‐sized rings by choosing the appropriate catalytic systems to direct the reaction to the alkene or to the pyrrole nucleus. These reactions can also be extended to the corresponding heteroaryl halides. Thus, reaction conditions have been established to access selectively to (hetero)fused indolizine, pyrroloazepine and pyrroloazocine systems.

  相似文献   

54.
Secondhand electronic cigarette (e-cigarette) aerosol (SHA) might impair indoor air quality and expose bystanders. This study aims to investigate exposure to SHA in controlled conditions of enclosed settings simulating real-world scenario. An experiment was performed in a car and in a room, in which SHA was generated during a 30-minute ad libitum use of an e-cigarette. The experiment was replicated on five consecutive days in each setting. We measured PM2.5, airborne nicotine concentrations, and biomarkers of exposure to SHA, such as nicotine metabolites, tobacco-specific nitrosamines, propylene glycol, and glycerol in bystanders’ saliva samples before, during, and after the exposure period. Self-reported health symptoms related to exposure to SHA were also recorded. The results showed that the highest median PM2.5 concentration was recorded during the exposure period, being 21 µg/m3 in the room setting and 16 µg/m3 in the car setting—about twofold increase compared to the baseline. Most concentrations of the airborne nicotine and all biomarkers were below the limit of quantification in both settings. Bystanders in both settings experienced some short-term irritation symptoms, expressed as dry throat, nose, eyes, and phlegm. In conclusion, short-term use of an e-cigarette in confined spaces increased indoor PM2.5 level and caused some irritation symptoms in bystanders.  相似文献   
55.

Background

Installations that burn fossil fuels to generate power may represent a health problem due to the toxic substances which they release into the environment.

Objectives

To investigate whether there might be excess mortality due to tumors of lung, larynx and bladder in the population residing near Spanish combustion installations included in the European Pollutant Emission Register.

Methods

Ecologic study designed to model sex-specific standardized mortality ratios for the above three tumors in Spanish towns, over the period 1994-2003. Population exposure to pollution was estimated on the basis of distance from town of residence to pollution source. Using mixed Poisson regression models, we analyzed: risk of dying from cancer in a 5-kilometer zone around installations that commenced operations before 1990; effect of type of fuel used; and risk gradient within a 50-kilometer radius of such installations.

Results

Excess mortality (relative risk, 95% confidence interval) was detected in the vicinity of pre-1990 installations for lung cancer (1.066, 1.041-1.091 in the overall population; 1.084, 1.057-1.111 in men), and laryngeal cancer among men (1.067, 0.992-1.148). Lung cancer displayed excess mortality for all types of fuel used, whereas in laryngeal and bladder cancer, the excess was associated with coal-fired industries. There was a risk gradient effect in the proximity of a number of installations.

Conclusions

Our results could support the hypothesis of an association between risk of lung, laryngeal and bladder cancer mortality and proximity to Spanish combustion installations.  相似文献   
56.
57.

The effects of Open Access (OA) upon journal performance are investigated. The key research question holds: How does the citation impact and publication output of journals switching (“flipping”) from non-OA to Gold-OA develop after their switch to Gold-OA? A review is given of the literature, with an emphasis on studies dealing with flipping journals. Two study sets with 119 and 100 flipping journals, derived from two different OA data sources (DOAJ and OAD), are compared with two control groups, one based on a standard bibliometric criterion, and a second controlling for a journal’s national orientation. Comparing post-switch indicators with pre-switch ones in paired T-tests, evidence was obtained of an OA Citation advantage but not of an OA Publication Advantage. Shifts in the affiliation countries of publishing and citing authors are characterized in terms of countries’ income class and geographical world region. Suggestions are made for qualitative follow-up studies to obtain more insight into OA flipping or reverse-flipping.

  相似文献   
58.
59.
The design of erodible biomaterials relies on the ability to program the in vivo retention time, which necessitates real-time monitoring of erosion. However, in vivo performance cannot always be predicted by traditional determination of in vitro erosion, and standard methods sacrifice samples or animals, preventing sequential measures of the same specimen. We harnessed non-invasive fluorescence imaging to sequentially follow in vivo material-mass loss to model the degradation of materials hydrolytically (PEG:dextran hydrogel) and enzymatically (collagen). Hydrogel erosion rates in vivo and in vitro correlated, enabling the prediction of in vivo erosion of new material formulations from in vitro data. Collagen in vivo erosion was used to infer physiologic in vitro conditions that mimic erosive in vivo environments. This approach enables rapid in vitro screening of materials, and can be extended to simultaneously determine drug release and material erosion from a drug-eluting scaffold, or cell viability and material fate in tissue-engineering formulations.  相似文献   
60.
The formation of the FeAl intermetallic compound has been investigated by annealing a mechanically milled powder and a mechanically cryoalloyed powder. First, the morphological transformations that result from both milling processes were analysed, giving special emphasis to the cryoalloyed powder; the evolution of continuous cold welding and fracturing during milling was assessed by means of scanning electron microscopy (SEM). The lattice parameter changes of both powders were then evaluated as a function of milling time using profile fitting and Rietveld analysis of the XRD data. The powder thermal stability was also examined by differential scanning calorimetry (DSC) and the detected transformations were discussed according to the structural changes observed in X-ray temperature-dependent measurements. Furthermore, M?ssbauer data has been used to compare the different atom rearrangements, from that of an ideal B2 structure and a typical bcc-Fe type to a disordered A2-solid solution and their temperature-induced ordering processes.  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