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   174篇
  免费   4篇
电工技术   1篇
化学工业   36篇
金属工艺   1篇
机械仪表   2篇
建筑科学   1篇
能源动力   6篇
轻工业   27篇
无线电   9篇
一般工业技术   28篇
冶金工业   60篇
原子能技术   2篇
自动化技术   5篇
  2022年   1篇
  2021年   2篇
  2020年   3篇
  2019年   4篇
  2018年   1篇
  2017年   2篇
  2015年   1篇
  2014年   5篇
  2013年   8篇
  2012年   6篇
  2011年   4篇
  2010年   3篇
  2009年   10篇
  2008年   11篇
  2007年   2篇
  2006年   3篇
  2005年   3篇
  2004年   1篇
  2003年   1篇
  2002年   3篇
  2001年   3篇
  2000年   2篇
  1999年   3篇
  1998年   24篇
  1997年   8篇
  1996年   8篇
  1995年   7篇
  1994年   2篇
  1993年   3篇
  1992年   3篇
  1991年   3篇
  1990年   2篇
  1989年   3篇
  1988年   2篇
  1987年   4篇
  1986年   5篇
  1985年   1篇
  1984年   3篇
  1983年   1篇
  1982年   2篇
  1981年   2篇
  1980年   1篇
  1978年   2篇
  1977年   2篇
  1976年   1篇
  1974年   1篇
  1973年   1篇
  1972年   2篇
  1970年   1篇
  1940年   1篇
排序方式: 共有178条查询结果,搜索用时 15 毫秒
51.
52.
The within-person influence of interpersonal stressors on affective well-being and physical well-being was investigated for 109 women with and without arthritis. Participants were interviewed on a weekly basis for 12 consecutive weeks, and the prospective data were analyzed by using hierarchical linear modeling. Overall, interpersonal workplace stressors independently predicted both well-being outcomes. Interpersonal stressors outside the workplace were related to negative affect but not to arthritis symptoms. Compared with healthy controls, arthritis patients' ratings of negative affect were equally reactive to workplace stressors. Neuroticism did not moderate stressor reactivity for either dependent variable but did predict mean levels of negative affect. The data support the hypothesis that the psychosocial environment of the workplace contributes unique effects on well-being. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
53.
To characterize the calcium (Ca2+)-releasing effects of histamine and GTP gamma S, the drug-induced tension developments were measured in beta-escin-treated skinned longitudinal smooth muscle of guinea pig ileum. Intracellular Ca2+ stores were loaded with Ca2+ by incubating the muscle for 10 min in a Ca(2+)-containing solution. Histamine (10-100 microM), applied after Ca(2+)-loading, produced a transient rise in tension. The effect of histamine was not preserved after treatment with 20 mM caffeine, a Ca(2+)-store releaser. The effect of histamine was potentiated by GTP; inhibited by GDP beta S, an antagonist of GTP for binding to G-proteins; or heparin, an antagonist of inositol 1,4,5-trisphosphate (IP3) for binding to its receptor; and mimicked by IP3. When GTP gamma S (20 microM) was applied and continued to be present for 15 min, a transient rise in tension followed by a small, sustained rise in tension was elicited. The effect of GTP gamma S was completely inhibited by GDP beta S. The initial, transient component of the biphasic GTP gamma S response was abolished or markedly inhibited after treatment with caffeine, heparin or the calcium ionophore A23187. The present results suggest that histamine and GTP gamma S cause a release of Ca2+ from caffeine-sensitive stores which is mediated by IP3 formed through a G-protein-coupled mechanism. The GTP gamma S-induced Ca2+ release is not considered to involve such an IP3-independent process as described in chemically-skinned arterial muscle.  相似文献   
54.
One fundamental problem of intelligent organisms pursuing goal-directed behavior is how to dynamically regulate the balance between maintenance and flexibility. The authors show that central dopaminergic activity, as indicated by spontaneous eyeblink rate and dopamine gene polymorphisms, plays an important role in the modulation of this balance. Seventy-two young adults were examined. Participants with high blink rates showed increased cognitive flexibility but decreased cognitive stability compared with participants with low blink rates. This pattern of results was even more pronounced for carriers of the DRD4 exon III 4/7 genotype, even though no main effects were found for DRD4 and COMT polymorphisms. Results converge with neuropsychological models that suggest a modulatory role of prefrontal dopaminergic activity for processes of cognitive control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
55.
An intelligent multi-sensor system with an entire autonomy, a low weight and a small size has been developed for in situ applications such as environmental pollutant gas detection or olfactory estimation. This portable electronic nose works with commercial metal oxide gas sensors and a microcontroller connected to a compact flash memory as intelligent unit. In this work we present the conception of this electronic nose, its laboratory validation, and a real application which concerns an outdoor air monitoring of a duck breeding. This application is developed in order to quantify continuously discomfort odor spread, causing neighbor complaints. The odor measurements were made using our electronic nose (Nepo) and results are compared to the simultaneous results obtained from other olfactometric techniques.  相似文献   
56.
57.
A new method for the spatially resolved measurement of the oxygen saturation of retinal vessels is described. Imaging spectrometry was used for both measurements of transmission and reflectance spectra of whole blood in cuvettes as well as for fundus reflectance spectra. A model was developed for the calculation of the oxygen saturation, valid in the wavelength range between 510 nm and 586 nm, in that the internal reflectance is constant and only the transmitted light depends on layer thickness and hematocrit. Altogether 265 measurements were performed in different number at 30 eyes. In each measurement, the oxygen saturation was simultaneously determined for 193 locations along a line of 1.5 mm at the fundus. The mean oxygen saturation in retinal arteries was (92.2 +/- 4.1)% and (57.9 +/- 9.9)% in retinal veins. The mean retinal arterio-venous difference of the oxygen saturation was (35.1 +/- 9.5)%. The venous oxygen saturation depended on distance from the optic disc. The measured mean of the arterio-venous difference of the oxygen saturation corresponded well to the value of the brain (34%). The utilization of oxygen in the temporal quadrants (inferior: 39.4 +/- 10.4%) is significantly (p = 0.05) higher than in the nasal quadrants (inferior: 31.3 +/- 6.7%).  相似文献   
58.
59.
60.
The Münsterländer Kiessandzug, a Quaternary trench structure, forms an important groundwater reservoir and is of great importance for the regional drinking water supply in north-west Germany (“Münsterland”). Since 2004, the Ruhr-University Bochum has been investigating the Aldruper Mark, evaluating the quantitative and qualitative potential for drinking water abstraction in the area. Due to intensive agricultural utilisation, a high nitrate influx into groundwater is expected. Therefore, this study was focused on contamination of groundwater with nitrate as well as on the nitrate degradation capacity of the sediments. However, present analyses show low nitrate concentrations and a reductive groundwater environment. To find the causes of these reducing conditions, it is necessary to examine the geological and hydrochemical situation with respect to the environment and the substratum of the investigated area: the MünsterländerCretaceous basin is underlain by Carboniferous sand- and mudstones which are degasing methane to some extent. This methane was detected in deep observation wells in the second aquifer of the Münsterländer Kiessandzug. In its central area, low concentrations of nitrate as well as low sulphate concentrations and positive δ34Ssulfate-isotope data indicate active sulphate reduction is occurring in the groundwater. Furthermore, a corresponding sulphide content was found in these Quaternary soils (“secondary pyrite”). An input of methane in the aquifer is discussed as a possible reason for sulphate reduction in the deep aquifer.  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