全文获取类型
收费全文 | 320篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 7篇 |
综合类 | 6篇 |
化学工业 | 53篇 |
金属工艺 | 3篇 |
机械仪表 | 9篇 |
建筑科学 | 42篇 |
矿业工程 | 2篇 |
能源动力 | 16篇 |
轻工业 | 18篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 27篇 |
一般工业技术 | 44篇 |
冶金工业 | 58篇 |
原子能技术 | 1篇 |
自动化技术 | 33篇 |
出版年
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2017年 | 5篇 |
2016年 | 4篇 |
2015年 | 2篇 |
2014年 | 8篇 |
2013年 | 24篇 |
2012年 | 10篇 |
2011年 | 10篇 |
2010年 | 12篇 |
2009年 | 13篇 |
2008年 | 20篇 |
2007年 | 18篇 |
2006年 | 24篇 |
2005年 | 8篇 |
2004年 | 8篇 |
2003年 | 8篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 12篇 |
1998年 | 5篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 6篇 |
1990年 | 7篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 7篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1977年 | 3篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1971年 | 2篇 |
1967年 | 2篇 |
1959年 | 2篇 |
1947年 | 1篇 |
排序方式: 共有322条查询结果,搜索用时 78 毫秒
21.
22.
The use of SP2340 glass capillary columns for the estimation of thetrans fatty acid content of foods
Glass capillary gas chromatography (GCGC) on 100-m and 60-m SP2340 columns was used for quantitation of thetrans unsaturated fatty acids in shortenings and fast foods. The separation of thecis andtrans octadecenoates on GCGC was evaluated by preparatory argentation thin layer chromatography. In addition, thetrans content of shortening samples obtained by GCGC was compared totrans content determined by infrared analysis.
This research conducted by the Science and Education Administration, USDA, on the commercial foods as reported in this paper
was limited to analysis of their lipid compositions. The data are reported solely as factual information and are limited to
the samples analyzed. No warranty or guarantee is made or implied that other samples of these products will have the same
or similar composition. It is the policy of the USDA not to endorse those commercial products used in research over those
that were not included in the research. 相似文献
23.
Hendrick HW 《Applied ergonomics》2003,34(5):419-427
Managers usually can justify financially supporting a proposed ergonomics project only when it is supported by a sound cost-benefit analysis. The factors to consider and sources of information for calculating the costs and benefits of proposed ergonomic projects are described. Based upon his experience and review of numerous ergonomics projects, the common characteristics of successful ergonomics interventions gleaned by the author are described and then illustrated by actual documented cases. 相似文献
24.
Spencer Graves Søren Bisgaard Murat Kulahci John Van Gilder John James Ken Marko Hal Zatorski Tom Ting Cuiping Wu 《Quality and Reliability Engineering International》2007,23(2):189-201
Modern products frequently feature monitors designed to detect actual or impending malfunctions. False alarms (Type I errors) or excessive delays in detecting real malfunctions (Type II errors) can seriously reduce monitor utility. Sound engineering practice includes physical evaluation of error rates. Type II error rates are relatively easy to evaluate empirically. However, adequate evaluation of a low Type I error rate is difficult without using accelerated testing concepts, inducing false alarms using artificially low thresholds and then selecting production thresholds by appropriate extrapolation, as outlined here. This acceleration methodology allows for informed determination of detection thresholds and confidence in monitor performance with substantial reductions over current alternatives in time and cost required for monitor development. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
25.
26.
Thomas P. Sullivan Douglas R. Crump Hal Wieser Elisabeth A. Dixon 《Journal of chemical ecology》1990,16(3):941-949
This paper reports on laboratory bioassays and a large-scale field trial of synthetic mustelid anal-gland compounds in controlled-release devices designed for operational application to burrow systems of northern pocket gophers (Thomomys talpoides). The field study was conducted in an apple orchard in the Okanagan Valley of British Columbia. In laboratory bioassays, a 1∶1 mixture of 2-propylthietane and 3-propyl-1,2-dithiolane from the stoat (Mustela erminea) and 3,3-dimethyl-1,2-dithiolane from the ferret (M. putorius), dispensed in clay pellets (activated alumina), produced a significant avoidance response by gophers. All resident gophers were permanently removed from 4-ha control and treatment blocks prior to placement of stoat odor in burrows. As indexed by soil mounds, significantly fewer gophers colonized the treatment (40) than the control (68) removal area during a 5.5-month overwinter experiment. There was also a significant difference when comparing the number of mounds between pre-(79) and posttreatment (40) censuses. In addition, most gopher activity tended to occur on the perimeter of the treatment block. Abundance of gophers showed little difference between additional 4-ha control and treatment blocks where gophers had not been removed. The results of this study provide an alternative technique to toxicants for pocket gopher control on forest and agricultural land. 相似文献
27.
28.
This paper deals with the influence of the transient response and group delay of digital filters on the MRI signal and its aspects in image reconstruction. The consequence of digital filtration on the acquired signal will be shown in the time domain (κ-space) for three basic imaging methods-echo scan, radial scan and spiral scan. The influence of the group delay and transient response of filters will be explained and a method will be proposed which compensates both these phenomena while retaining all the advantages of digital filtration. The proposed method is based on applying the principle of signal superposition and on using the consequences of the sampling principle. The method works in the time domain. It is very simple and rapid and does not depend on the properties of the acquired signal or reconstruction algorithm. It will be shown and explained in which cases the transient response can be neglected and in which it has to be compensated. In the end, the results of the proposed methods will be shown for mentioned cases on a simulated signal in the image domain. © 1998 Elsevier Science B.V. All rights reserved. 相似文献
29.
Hal Philipp 《电子设计技术》2009,16(4):62-63,68
现今社会上很多人都频繁地接触到触摸屏。这种装置最常见于PDA和手机等手持设备和售票终端系统等应用,其中大部分都基于电阻性技术。电阻性技术采用一个柔性外层,其压触固定内层时,会产生电信号,然后转换为X-Y坐标位置。此外,还有其它两种常用技术:表面声波(SAW)和电容感测技术,不过,一直以来,由于成本和构建的限制,这两种技术都仅用在公用信息服务应用(Kiosk applications)中。 相似文献
30.
Schuldberg David; Quinlan Donald M.; Morgenstern Hal; Glazer William 《Canadian Metallurgical Quarterly》1990,2(3):262
This study evaluates 2 instruments measuring positive and negative symptoms, the Scale for the Assessment of Negative Symptoms and the Scale for the Assessment of Positive Symptoms, for their reliability, internal consistency, and temporal stability. The interrelationships and course of specific symptoms are examined to ask whether they represent 1, 2, or more separate pathological processes. Symptoms were assessed in 399 outpatients followed for the long-term effects of antipsychotic medications; a subset (n?=?229) was given the instruments twice, approximately 24 months apart. Results suggest four distinct types of symptoms in severe mental disorders. Two correspond to general definitions of positive and negative symptoms. Attentional Impairment, Formal Thought Disorder, and possibly Bizarreness and Avolition-Apathy emerge as separate categories of symptoms. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献