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   109篇
  免费   4篇
电工技术   5篇
化学工业   28篇
金属工艺   1篇
机械仪表   2篇
建筑科学   2篇
能源动力   6篇
轻工业   12篇
石油天然气   1篇
无线电   6篇
一般工业技术   20篇
冶金工业   16篇
原子能技术   1篇
自动化技术   13篇
  2024年   1篇
  2021年   3篇
  2020年   4篇
  2019年   3篇
  2018年   1篇
  2017年   1篇
  2016年   3篇
  2015年   9篇
  2014年   5篇
  2013年   8篇
  2012年   2篇
  2011年   6篇
  2010年   6篇
  2009年   3篇
  2008年   2篇
  2007年   3篇
  2006年   2篇
  2005年   4篇
  2004年   2篇
  2003年   2篇
  2002年   2篇
  2001年   3篇
  1999年   3篇
  1998年   7篇
  1997年   3篇
  1996年   2篇
  1995年   2篇
  1994年   2篇
  1993年   3篇
  1992年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1985年   3篇
  1983年   2篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1977年   2篇
  1976年   1篇
  1974年   1篇
排序方式: 共有113条查询结果,搜索用时 0 毫秒
41.
A numerical study, using the volume‐of‐fluid method, has been made of vertical (upward) laminar core‐annular flow: the flow of a high‐viscosity liquid core surrounded by a laminar low‐viscosity liquid annular layer through a vertical pipe. The numerical results are compared with theoretical results from linear stability calculations and with experimental data. The comparison is good and the general conclusion of our study is that it is very well possible to simulate laminar core‐annular flow in a pipe using the volume‐of‐fluid method. © 2014 The Authors. AIChE Journal, published by Wiley on behalf of the AIChE. AIChE J, 60: 3046–3056, 2014  相似文献   
42.
Six methods were compared for detection of three strains of Escherichia coli O157:H7 in enrichments of inoculated apple juice. Juice was inoculated at levels varying from 0.1 to 100 CFU/ml and centrifuged after overnight storage at 4 degrees C, and pellets were incubated at 37 degrees C in nonselective enrichment broth. At hourly intervals between 5 and 10 h and at 24 h, the enrichments were tested for E. coli O157:H7 by direct fluorescent antibody (DFA), antibody-direct epifluorescent filter technique (Ab-DEFT), direct selective plating on sorbitol MacConkey agar (SMA), immunomagnetic separation coupled to either selective plating (IMS-SMA) or the polymerase chain reaction (IMS-PCR), and flow cytometry (FC). The most consistent detection of 0.1 CFU/ml of the slowest growing strain of the pathogen was provided by the IMS-SMA and IMS-PCR after 8 h of enrichment. The time required for detection at the level of 0.1 CFU/ml for each assay was Ab-DEFT, 11 h; IMS-PCR, 16 h; FC, 24 h; IMS-SMA, 32 h; and SMA, 48 h. Absolute detection limits (without enrichment) were: IMS-PCR, 10(3) CFU/ml; Ab-DEFT and IMS-SMA, 10(4) CFU/ml; SMA, 10(5) CFU/ml; and DFA, 10(6) CFU/ml. Recovery of the pathogen (10 CFU/ml) in apple juice after 28 days of 4 degrees C storage was possible by means of an 8-h enrichment and Ab-DEFT, IMS-PCR, or IMS-SMA.  相似文献   
43.
Chronic illness places considerable burdens on patients and their interpersonal relations with families. In this study, patients' perceptions of family and medical staff expectations regarding responsibility for care and routine functions were examined. The authors hypothesized that a patient's perceived inability to meet others' expectations about coping with illness would lead to poorer adjustment. Forty-two chronically ill patients were assessed prospectively for perceptions of others' expectations, social support, and psychological adjustment. Findings confirmed that expectations predicted subsequent decreases in psychological adjustment over a 3-month period, even when social support was controlled. A test of the reverse hypothesis showed that poorly adjusted patients did not misperceive others' expectations. Theoretical interpretations of the findings and their relation to social support research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
44.
45.
The authors carried out experiments on animals (40 white male rats) which were subjected to daily a two-hour action of the common vertical sinusoidal vibrations with a frequency of 20 Hr (I group) and 50 Hr (II group) with acceleration of 22,0 m/sec2 for a period of ten days (I group--A and second group--A) and 30 days (I group--B and II group--B). Histomorphological and histochemical methods were used and the authors found changes in microcirculation and structure of the intestinal wall manifested in the animals of the II group. The obtained results were in support of the clinical data on the disturbances in intestinal function in patients with vibration disease and corresponded to the experimental data on the occurrence of vascular and dystrophic changes in the internal organs under vibration action.  相似文献   
46.
A theoretical model has been developed to describe heat transfer to a fluid which is flowing turbulently in a pipe and within which a first-order endothermic irreversible chemical reaction is taking place. It is based on the penetration model for the fluid boundary layer close to the pipe wall and enables the calculation of the effect of chemical reaction on the heat transfer coefficient of turbulent pipe flow.The model has been checked against experimental results for flow distribution and heat transfer in turbulent pipe flow without chemical reaction. Good agreement between the calculated and experimental results was found. The measured heat transfer coefficients for turbulent pipe flow with a uniformly distributed heat source within the fluid were also well predicted. Unfortunately no accurate experimental data on the effect of a first-order chemical reaction on the heat transfer coefficient of turbulent pipe flow are available. However, calculations made with the model show that this effect can be considerable and thus may not always be neglected in practice.  相似文献   
47.
Zinc deficiency during pregnancy affects the outcome of pregnancy. A high prevalence of zinc deficiency (55.5%) has been reported among pregnant women. It is not known whether pregnancy leads to zinc deficiency due to the increased fetal needs or whether the women are zinc deficient when they become pregnant. No data are available on the zinc status of nulliparous nonpregnant women from India. To assess the magnitude of zinc deficiency among nulliparous nonpregnant women in a rural community of Haryana State, India. A community-based cross-sectional survey was conducted in six villages of a rural area in a district of Haryana State, India. All nulliparous nonpregnant women aged 18 years or over who were willing to participate in the study were enrolled. Each woman was questioned about her age, socioeconomic status, and dietary pattern with the use of a pretested semistructured questionnaire. Blood from the antecubital vein was drawn to assess the serum zinc levels using an atomic absorption spectrophotometer. Serum zinc levels less than 70.0 micrograms/dl were considered to indicate zinc deficiency. The dietary intakes of zinc, protein, and calories were assessed by the 24-hour dietary recall method. Two hundred eighty-eight nulliparous nonpregnant women were enrolled. Forty-one percent had zinc deficiency, and 75.7%, 1.4%, and 7.3% of the women consumed less than 50% of the recommended intake of zinc, protein, and calories, respectively. Women who consumed less than 50% of the recommended intake of calories (1,875 kcal) were at a 4.9 times higher risk of zinc deficiency than women who consumed more than 50% of the recommended intake. A high prevalence of zinc deficiency was found among the nulliparous nonpregnant women in the area studied.  相似文献   
48.
A numerical study has been made of laminar core‐annular through a torus. It is a follow‐up of the study by Picardo and Pushpavanam, AIChE J. 2013;59(12):4871–4886, who obtained an analytical solution for the case that the core is concentric and circular. In our study, we investigated the possibility of eccentric core‐annular flow and the deformation of the core‐annular interface. We found that a stable eccentric core position is possible, which is shifted in the direction of the inner or outer side of the torus depending on the balance of the normal stresses at the core‐annular interface. When these stresses are too far off from those for concentric and circular core‐annular flow, fouling of the wall occurs. We compared the results of core‐annular flow in a torus with those for a 90° pipe bend and found that the flow pattern in the torus is representative for the flow pattern in the bend. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2319–2328, 2015  相似文献   
49.
A practical nickel‐catalysed approach has been developed for the C S bond formation through the cross‐coupling of arylsulfonyl hydrazides and aryl boronic acids. The report employs arylsulfonyl hydrazide as an aryl thiol equivalent and offers a mild and eco‐safe synthesis of unsymmetrical thioethers in good to excellent yields in air. The scope and versatility of the method has been successfully demonstrated with 22 examples.

  相似文献   

50.

Background

With the increasing use of nanomaterials, the need for methods and assays to examine their immunosafety is becoming urgent, in particular for nanomaterials that are deliberately administered to human subjects (as in the case of nanomedicines). To obtain reliable results, standardised in vitro immunotoxicological tests should be used to determine the effects of engineered nanoparticles on human immune responses. However, before assays can be standardised, it is important that suitable methods are established and validated.

Results

In a collaborative work between European laboratories, existing immunological and toxicological in vitro assays were tested and compared for their suitability to test effects of nanoparticles on immune responses. The prototypical nanoparticles used were metal (oxide) particles, either custom-generated by wet synthesis or commercially available as powders. Several problems and challenges were encountered during assay validation, ranging from particle agglomeration in biological media and optical interference with assay systems, to chemical immunotoxicity of solvents and contamination with endotoxin.

Conclusion

The problems that were encountered in the immunological assay systems used in this study, such as chemical or endotoxin contamination and optical interference caused by the dense material, significantly affected the data obtained. These problems have to be solved to enable the development of reliable assays for the assessment of nano-immunosafety.  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