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   332篇
  免费   25篇
  国内免费   1篇
电工技术   2篇
化学工业   59篇
金属工艺   3篇
机械仪表   2篇
建筑科学   15篇
矿业工程   1篇
能源动力   4篇
轻工业   41篇
水利工程   2篇
石油天然气   2篇
无线电   45篇
一般工业技术   62篇
冶金工业   53篇
原子能技术   11篇
自动化技术   56篇
  2023年   4篇
  2021年   4篇
  2020年   8篇
  2019年   5篇
  2018年   7篇
  2017年   17篇
  2016年   7篇
  2015年   8篇
  2014年   12篇
  2013年   19篇
  2012年   12篇
  2011年   12篇
  2010年   11篇
  2009年   17篇
  2008年   14篇
  2007年   11篇
  2006年   15篇
  2005年   13篇
  2004年   8篇
  2003年   12篇
  2002年   8篇
  2001年   13篇
  2000年   6篇
  1999年   4篇
  1998年   19篇
  1997年   19篇
  1996年   6篇
  1995年   9篇
  1994年   4篇
  1993年   6篇
  1992年   5篇
  1991年   4篇
  1989年   1篇
  1988年   3篇
  1986年   2篇
  1978年   1篇
  1976年   5篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
  1970年   2篇
  1966年   1篇
  1964年   6篇
  1963年   2篇
  1962年   4篇
  1961年   1篇
  1960年   2篇
  1959年   1篇
  1958年   1篇
  1957年   1篇
排序方式: 共有358条查询结果,搜索用时 11 毫秒
21.
采用闪急混合工艺使得在最接近流浆箱处向浆料中加入助留剂和施胶化学品等造纸添加剂,并使之迅速和有效地混合。这项多功能混合技术可以做到在同一地点同时将填料、助留剂一起加入到流浆箱中。该工艺操作简单,具有非常短的响应时间,填料留着率更高,纸张性能更优越。由于减少了添加剂在过程中的循环,响应时间非常快速,减少了传统混合过程的水或滤液的量,从而降低了能源消耗,降低了添加剂用量并使工艺过程净化。  相似文献   
22.
The objective of these investigations was to determine the possible effects of the novel selective estrogen receptor modulator, ospemifene, on cytochrome P450 (CYP)-mediated drug metabolism. Ospemifene underwent testing for possible effects on CYP enzyme activity in human liver microsomes and in isolated human hepatocytes. Based on the results obtained in vitro, three Phase 1 crossover pharmacokinetic studies were conducted in healthy postmenopausal women to assess the in vivo effects of ospemifene on CYP-mediated drug metabolism. Ospemifene and its main metabolites 4-hydroxyospemifene and 4′-hydroxyospemifene weakly inhibited a number of CYPs (CYP2B6, CYP2C9, CYP2C19, CYP2C8, and CYP2D6) in vitro. However, only CYP2C9 activity was inhibited by 4-hydroxyospemifene at clinically relevant concentrations. Induction of CYPs by ospemifene in cultured human hepatocytes was 2.4-fold or less. The in vivo studies showed that ospemifene did not have significant effects on the areas under the plasma concentration-time curves of the tested CYP substrates warfarin (CYP2C9), bupropion (CYP2B6) and omeprazole (CYP2C19), demonstrating that pretreatment with ospemifene did not alter their metabolism. Therefore, the risk that ospemifene will affect the pharmacokinetics of drugs that are substrates for CYP enzymes is low.  相似文献   
23.
The authors consider the production experience of a separator of the new generation with constant magnets based on Nd – Fe – B, which was designed by ÉMKO Company for producing quartz glass concentrates of grades OVS-030 and OVS-025, using dry magnetic separation. The proposed separator has several advantages compared to electromagnetic separators of the EVS series, which have the same purpose.  相似文献   
24.
In this review we present the results of our literature investigation into the electrical and thermal properties of carbon nanotube polymer composites. A short selection of data relating to conductive polymer composites with various fillers is provided for comparison. The effects of filler properties such as type and size, the use of hybrid fillers, fabrication methods for polymer composites and the importance of the modeling of the electronic and thermal transport mechanisms are discussed, as are more general factors influencing the properties of these composites. This review represents a comprehensive survey and constructive study and should serve as a useful reference tool for industrial and academic researchers working in this field. © 2017 Society of Chemical Industry  相似文献   
25.
Department of Intelligent Hydraulics and Automation (IHA) of Tampere University of Technology has been involved in the European Fusion program since 1994 within the ITER reactor maintenance activities. In this paper we discuss the design and development of a six degrees of freedom water hydraulic manipulator with a force feedback for teleoperation tasks. The manipulator is planned to be delivered to Divertor Test Platform 2 (DTP2) during year 2008. The paper also discusses the possibility to improve the fail safe and redundant operation of the manipulator. During the design of the water hydraulic manipulator, special provisions have been made in order to meet the safety requirements such as servo valve block for redundant operation and safety vane brakes for fail safe operation.  相似文献   
26.
Multimodal function optimization, where the aim is to locate more than one solution, has attracted growing interest especially in the evolutionary computing research community. To evaluate experimentally the strengths and weaknesses of multimodal optimization algorithms, it is important to use test functions representing different characteristics and various levels of difficulty. The available selection of multimodal test problems is, however, rather limited and no general framework exists. This paper describes an attempt to construct a software framework which includes a variety of easily tunable test functions. The aim is to provide a general and easily expandable environment for testing different methods of multimodal optimization. Several function families with different characteristics are included. The framework implements new parameterizable function families for generating desired landscapes. Additionally the framework implements a selection of well known test functions from the literature, which can be rotated and stretched. The software module can easily be imported to any optimization algorithm implementation compatible with the C programming language. As an application example, 8 optimization approaches are compared by their ability to locate several global optima over a set of 16 functions with different properties generated by the proposed module. The effects of function regularity, dimensionality and number of local optima on the performance of different algorithms are studied.  相似文献   
27.
The fire risk assessment model CRISP2 was applied to a 4‐storey apartment building. The case building was an actual 4‐storey timber‐framed building. Partly predetermined design alternatives were used in sequential simulations. CRISP2 cannot take into account the frame‐material of the building in a satisfactory way, because the wall thickness, structural fire resistance or lining materials in the fire room cannot be modelled. It was found that adding smoke alarms almost halved the risk level. The risk levels 1–2×10?5 obtained are not far from comparable levels of fire death statistics from Finland, the United Kingdom, Sweden and Norway. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
28.
The monitoring of snow water equivalent (SWE) and snow depth (SD) in boreal forests is investigated by applying space-borne microwave radiometer data and synoptic snow depth observations. A novel assimilation technique based on (forward) modelling of observed brightness temperatures as a function of snow pack characteristics is introduced. The assimilation technique is a Bayesian approach that weighs the space-borne data and the reference field on SD interpolated from discrete synoptic observations with their estimated statistical accuracy. The results obtained using SSM/I and AMSR-E data for northern Eurasia and Finland indicate that the employment of space-borne data using the assimilation technique improves the SD and SWE retrieval accuracy when compared with the use of values interpolated from synoptic observations. Moreover, the assimilation technique is shown to reduce systematic SWE/SD estimation errors evident in the inversion of space-borne radiometer data.  相似文献   
29.
Zusammenfassung Zum Nachweis von Isopropanol bei gleichzeitiger Anwesenheit von Methanol, Äthanol und Wasser wurde eine gaschromatographische Methode entwickelt. Die für diesen Zweck günstige Gesamtlänge der Kolonne beträgt 2,84 m, wovon der 2,24 m lange Anfangsteil mit Paraffinphase und der 0,6 m lange Schlußteil mit Polyäthylenglykolphase gefüllt ist. Als empfehlenswerte Temperatur für die Chromatographierung wird 47° C angegeben, wobei die Retentionszeiten für Methanol 12,1 min, für Äthanol 20,0 min, für Isopropanol 25,0 min und für Wasser 36 min betragen. Die Methode eignet sich ebenfalls gut zur quantitativen Bestimmung kleiner Äthanolmengen (1–3 Gew.-%) in Isopropanol.  相似文献   
30.
Good reliability of Caco-2 permeability studies requires competent sampling and analytical methods to ensure the comparability of day-to-day experiments. In this work, two n-in-one LC/MS/MS methods based on two different ionization techniques were developed and validated for a group of reference compounds; eight of them are recommended by the Food and Drug Administration (FDA) for the evaluation of oral drug permeability. The performance of a new ionization technique, atmospheric pressure photoionization (APPI), as an interface for quantitative LC/MS analysis was evaluated in comparison to the electrospray ionization (ESI). Generally, the validation parameters, including sensitivity, accuracy, and repeatability, were comparable for the APPI and ESI methods. The main difference was that the linear quantitative range of APPI was 3-4 orders of magnitude (r(2) >/= 0.998) whereas in ESI it was typically 2-3 orders of magnitude (r(2) >/= 0.990). By the APPI and ESI methods, the simultaneous analysis of nine highly heterogeneous compounds was achieved within 5.5-7 min, which leads to significant savings in time and cost of the analyses. The successful validation data indicate the usefulness of both the methods for the rapid and sensitive (LOD values typically 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