全文获取类型
收费全文 | 396篇 |
免费 | 2篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 70篇 |
金属工艺 | 3篇 |
机械仪表 | 6篇 |
建筑科学 | 41篇 |
能源动力 | 4篇 |
轻工业 | 32篇 |
水利工程 | 4篇 |
石油天然气 | 1篇 |
无线电 | 37篇 |
一般工业技术 | 46篇 |
冶金工业 | 130篇 |
自动化技术 | 23篇 |
出版年
2020年 | 4篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 10篇 |
2015年 | 4篇 |
2014年 | 8篇 |
2013年 | 31篇 |
2012年 | 7篇 |
2011年 | 9篇 |
2010年 | 4篇 |
2009年 | 5篇 |
2008年 | 16篇 |
2007年 | 17篇 |
2006年 | 10篇 |
2005年 | 11篇 |
2004年 | 11篇 |
2003年 | 6篇 |
2002年 | 13篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 8篇 |
1998年 | 21篇 |
1997年 | 20篇 |
1996年 | 12篇 |
1995年 | 13篇 |
1994年 | 9篇 |
1993年 | 14篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1975年 | 2篇 |
1973年 | 2篇 |
1947年 | 3篇 |
1946年 | 4篇 |
1945年 | 4篇 |
1944年 | 4篇 |
1943年 | 2篇 |
1942年 | 2篇 |
1941年 | 2篇 |
1940年 | 2篇 |
排序方式: 共有400条查询结果,搜索用时 15 毫秒
1.
Based on an idea introduced by Benjamin and Cornell (1970. Probability, statistics and decision for civil engineers. New York: McGaw Hill) and previous works by the authors it is demonstrated how condition indicators may be formulated for the general purpose of quality control and for assessment and inspection planning in particular. The formulation facilitates quality control based on sampling of indirect information about the condition of the considered components. This allows for a Bayesian formulation of the indicators whereby the experience and expertise of the inspection personnel may be fully utilized and consistently updated as frequentistic information is collected. The approach is illustrated on an example considering a concrete structure subject to corrosion. It is shown how half-cell potential measurements may be utilized to update the probability of excessive repair after 50 years. Furthermore in the same example it is shown how the concept of condition indicators might be applied to develop a cost optimal maintenance strategy composed of preventive and corrective repair measures. 相似文献
2.
Few studies have prospectively examined the characteristics associated with worksite adoption of tobacco-control initiatives. Data were collected as part of the Community Intervention Trial (COMMIT) for Smoking Cessation, which conducted interventions in 11 communities. This smoking cessation intervention was based on community organization principles and delivered through multiple community channels, including worksites, health care providers, the media, and cessation resources. This article reports results from telephone interviews of intervention community worksites having 50 or more employees, conducted at baseline and the end of the intervention period. Among worksites that responded to both baseline and final surveys, 83% had not adopted a smoke-free policy at baseline, and 61% did not offer any cessation aid or quitting resources at baseline. By the final survey, 34% of those with no smoking ban at baseline had become smoke-free, and 36% of those offering no cessation assistance at baseline were offering cessation resources at the follow-up. The prevalence of policy adoption was higher among worksites employing more female employees and offering other health-promotion activities; manufacturing businesses were significantly less likely than businesses other than service and wholesale/retail businesses to adopt policies. Adoption of cessation programs was significantly more likely among worksites employing 100 to 249 workers, compared with those employing 50 to 99 workers; those predominantly employing men; those offering other types of health-promotion activities; and those with a higher rate of turnover. These results provide important information about the characteristics of worksites likely to engage in tobacco-control efforts. Health educators and others may choose to target those worksites most ready for adoption of tobacco control policies and programs, as indicated by these findings. 相似文献
3.
Treatment of the addictions is changing. Psychosocial treatment programs and research projects have changed the way helping professionals view, treat, and prevent drug abuse. This article reviews the contributions included in this special series; they encompass several general issues facing psychologists who conduct treatment, research, and teaching in the field of addictive behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
4.
R Albrecht TC Awes C Baktash P Beckmann F Berger R Bock G Claesson G Clewing L Dragon A Eklund RL Ferguson A Franz S Garpman R Glasow HA Gustafsson HH Gutbrod J Idh P Jacobs K Kampert BW Kolb P Kristiansson IY Lee H Loehner I Lund FE Obenshain A Oskarsson I Otterlund T Peitzmann S Persson F Plasil AM Poskanzer M Purschke H Ritter S Saini R Santo HR Schmidt T Siemiarczuk SP Sorensen E Stenlund ML Tincknell GR Young 《Canadian Metallurgical Quarterly》1991,44(6):2736-2752
5.
Thompson Karin E.; Malow Robert M.; Corrigan Sheila A.; Sorensen James L. 《Canadian Metallurgical Quarterly》1992,6(2):67
Drug users are particularly at risk for contracting the human immunodeficiency virus and serve as a major mechanism for spreading the virus to other sectors of the population. As a result drug abuse treatment and potential behavioral change strategies are primary public health issues. The purpose of this article is to review the contributions included in this special edition, which represent an effort to describe the most current thinking in the field with a blend of theoretical, review, and empirical articles. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
6.
7.
8.
Steven B. Kuzyk Alexander O. Pritchard Jocelyn Plouffe John L. Sorensen Vladimir Yurkov 《Journal of Great Lakes research》2021,47(3):715-724
Violet and purple bacterial pigmentations are uncommon when considering strict aerobes. Here we report discovery of two novel isolates, P102 and P117 from the freshwater Lake Winnipeg, each with violet to deep purple colony colouration. The relationship between pigment production and growth was investigated under different conditions, including a variety of carbon sources, pH, and temperatures. The violet compounds were purified using polar organic solvents, and then structurally characterized via mass spectrometry and nuclear magnetic resonance to be violacein and deoxyviolacein. Strain P117 produced higher concentrations of the darker pigment deoxyviolacein, which resulted in a deeper hue of violet than in cultures of P102. Strain P102, synthesized violacein maximally in liquid rich organic medium at pH 8 and 20 °C, and had 99.3% sequence similarity to the 16S rDNA from Janthinobacterium lividum. Strain P117, related to Massilia violaceinigra sharing 99.2% 16S rDNA sequence similarity, also produced violacein at similar optimal conditions, but developed higher concentrations of pigment at 15 °C. Culture-based methods found that violacein producers composed 0.001% or 0.023% CFU of environmental heterotrophic populations using BG-11 and potato-based media, respectively. Culture-independent high-throughput ribosomal 16S V4 sequencing of environmental DNA was used to detect Gram-negative species known for their production of violacein. Of all bacterial and archaeal sequences present during the fall in littoral waters and sediment of Lake Winnipeg, 5.5% and 6.3%, respectively, belonged to species that have similar pigment, demonstrating the scarcity of violacein producers in this aquatic freshwater system. 相似文献
9.
10.
C. M. Sorensen 《International Journal of Thermophysics》1982,3(4):365-369
Shear viscosity measurements of a mixture of 3-methylpentane and nitroethane at the critical concentration are presented in the temperature range 0.005 KT–T
c13.93 K, where T
c is the consolute or critical temperature. The data agree with earlier measurements. 相似文献