全文获取类型
收费全文 | 1709篇 |
免费 | 50篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 8篇 |
化学工业 | 302篇 |
金属工艺 | 16篇 |
机械仪表 | 12篇 |
建筑科学 | 87篇 |
矿业工程 | 3篇 |
能源动力 | 24篇 |
轻工业 | 172篇 |
水利工程 | 10篇 |
石油天然气 | 2篇 |
无线电 | 83篇 |
一般工业技术 | 196篇 |
冶金工业 | 662篇 |
原子能技术 | 5篇 |
自动化技术 | 179篇 |
出版年
2022年 | 28篇 |
2021年 | 54篇 |
2020年 | 25篇 |
2019年 | 28篇 |
2018年 | 25篇 |
2017年 | 20篇 |
2016年 | 24篇 |
2015年 | 24篇 |
2014年 | 44篇 |
2013年 | 100篇 |
2012年 | 71篇 |
2011年 | 63篇 |
2010年 | 60篇 |
2009年 | 54篇 |
2008年 | 73篇 |
2007年 | 57篇 |
2006年 | 55篇 |
2005年 | 49篇 |
2004年 | 48篇 |
2003年 | 20篇 |
2002年 | 52篇 |
2001年 | 40篇 |
2000年 | 35篇 |
1999年 | 36篇 |
1998年 | 22篇 |
1997年 | 22篇 |
1996年 | 31篇 |
1995年 | 28篇 |
1994年 | 36篇 |
1993年 | 42篇 |
1992年 | 40篇 |
1991年 | 11篇 |
1990年 | 37篇 |
1989年 | 34篇 |
1988年 | 33篇 |
1987年 | 31篇 |
1986年 | 23篇 |
1985年 | 31篇 |
1984年 | 32篇 |
1983年 | 21篇 |
1982年 | 15篇 |
1981年 | 16篇 |
1980年 | 15篇 |
1979年 | 26篇 |
1978年 | 16篇 |
1977年 | 11篇 |
1976年 | 14篇 |
1975年 | 19篇 |
1973年 | 9篇 |
1972年 | 12篇 |
排序方式: 共有1761条查询结果,搜索用时 15 毫秒
91.
92.
Pope Benjamin; Blass Thomas; Cheek Judith; Siegman Aron W.; Bradford Norman H. 《Canadian Metallurgical Quarterly》1971,36(1):152
Attempted to replicate earlier findings by B. Pope and A. W. Siegman (see PA, Vol. 39:13386, and Vol. 40:509) that there is an inverse relationship between interviewer specificity and both interviewee productivity and uncertainty, through the use of more naturalistic interviewers. 24 18-40 yr. old psychiatric inpatients were interviewed 3 times in a low specificity, high specificity, and an uncontrolled interview. Previous findings were supported. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
93.
Weckler Nora; Wollersheim Janet P.; Goggin Judith P.; Dunham Frances Y.; Ferraro Douglas P.; White Kathleen M.; Benimoff Murray; Pate James L. 《Canadian Metallurgical Quarterly》1982,37(12):1380
Reports for 1982 are listed for the following regional association meetings: Sixty-Second Annual Meeting of the Western Psychological Association; Fifty-Second Annual Meeting of the Rocky Mountain Psychological Association; Fifty-Fourth Annual Meeting of the Midwestern Psychological Association; Twenty-Eighth Annual Meeting of the Southeastern Psychological Association; Twenty-Eighth Annual Meeting of the Southwestern Psychological Association; Twenty-Second Annual Meeting of the New England Psychological Association; Fifty-Third Annual Meeting of the Eastern Psychological Association; and Seventy-Fourth Annual Meeting of the Southern Society for Philosophy and Psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
94.
Growth and metabolism of five probiotic strains with well-documented health effects were studied in ultra-high temperature (UHT) treated milk, supplemented with 0.5% (w/v) tryptone or 0.75% (w/v) fructose. The probiotic strains were Lactobacillus acidophilus La5, Lb. acidophilus 1748, Lactobacillus rhamnosus GG, Lactobacillus reuteri SD 2112 and Bifidobacterium animalis BB12. Fermentation was followed for 72 h at 37 degrees C and the samples were analysed for pH, log cfu ml(-1), volatile compounds, organic acids and carbon dioxide. The strains reduced pH from 6.7 to between 3.9 and 4.4 after 24 h of incubation. All strains attained viable cell counts above 8.7-9.18 log cfu ml(-1) after 6-16 h of incubation. The two Lb. acidophilus strains showed a stable level of viable cells during 12-72 h of incubation but the three other strains showed a reduction of 0.4-1.1 log cfu ml(-1) from 24 to 72 h of incubation. However, all strains showed cell levels between 7.8 and 8.7 log cfu ml(-1) after 72 h of incubation. After 48 h of incubation, the amount of lactic acid produced varied according to strain from 6949 to 14,000 mg kg(-1) and acetic acid produced varied from 0 to 6901 mg kg(-1). Three of the strains metabolised citrate but only low amounts of diacetyl and acetoin were detected within strains, 0.2-0.8 and 6.5-10 mg kg(-1), respectively. Carbon dioxide produced varied from 221 to 3942 mg kg(-1) and was connected to the citrate-fermenting ability of the strain used and their carbohydrate fermentation pathway. Three of the strains produced detectable levels of acetaldehyde and the concentration varied from 9.4 to 12.6 mg kg(-1) after 24 h of incubation. All five probiotic strains showed very different profiles of metabolites during fermentation; however, the two Lb. acidophilus strains were the most alike. Our findings show the importance of controlling the fermentation time since the probiotic strains produced different amounts of metabolic products according to fermentation time. 相似文献
95.
Judith Bayard Cushing Nalini Nadkarni Michael Finch Anne Fiala Emerson Murphy-Hill Lois Delcambre David Maier 《Journal of Intelligent Information Systems》2007,29(1):7-24
To solve today’s ecological problems, scientists need well documented, validated, and coherent data archives. Historically,
however, ecologists have collected and stored data idiosyncratically, making data integration even among close collaborators
difficult. Further, effective ecology data warehouses and subsequent data mining require that individual databases be accurately
described with metadata against which the data themselves have been validated. Using database technology would make documenting
data sets for archiving, integration, and data mining easier, but few ecologists have expertise to use database technology
and they cannot afford to hire programmers. In this paper, we identify the benefits that would accrue from ecologists’ use
of modern information technology and the obstacles that prevent that use. We describe our prototype, the Canopy
DataBank, through which we aim to enable individual ecologists in the forest canopy research community to be their own database programmers.
The key feature that makes this possible is domain-specific database components, which we call templates. We also show how additional tools that reuse these components, such as for visualization, could provide gains in productivity
and motivate the use of new technology. Finally, we suggest ways in which communities might share database components and
how components might be used to foster easier data integration to solve new ecological problems. 相似文献
96.
Umer Farooq Patricia Schank Alexandra Harris Judith Fusco Mark Schlager 《Computer Supported Cooperative Work (CSCW)》2007,16(4-5):397-429
Community computing has recently grown to become a major research area in human–computer interaction. One of the objectives
of community computing is to support computer supported cooperative work among distributed collaborators working toward shared
professional goals in online communities of practice. A core issue in designing and developing community computing infrastructures
– the underlying socio-technical layer that supports communitarian activities – is sustainability. Many community computing
initiatives fail because the underlying infrastructure does not meet end user requirements; the community is unable to maintain
a critical mass of users consistently over time; it generates insufficient social capital to support significant contributions
by members of the community; or, as typically happens with funded initiatives, financial and human capital resource become
unavailable to further maintain the infrastructure. Based on more than nine years of design experience with Tapped In – an
online community of practice for education professionals – we present a case study that discusses four design interventions
that have sustained the Tapped In infrastructure and its community to date. These interventions represent broader design strategies
for developing online environments for professional communities of practice. 相似文献
97.
Cooney Ned L.; Litt Mark D.; Cooney Judith L.; Pilkey David T.; Steinberg Howard R.; Oncken Cheryl A. 《Canadian Metallurgical Quarterly》2007,21(4):570
Alcohol dependent smokers (N=118) enrolled in an intensive outpatient substance abuse treatment program were randomized to a concurrent brief or intensive smoking cessation intervention. Brief treatment consisted of a 15-min counseling session with 5 min of follow-up. Intensive intervention consisted of three 1-hr counseling sessions plus 8 weeks of nicotine patch therapy. The cigarette abstinence rate, verified by breath carbon monoxide, was significantly higher for the intensive treatment group (27.5%) versus the rate for the brief treatment group (6.6%) at 1 month after the quit date but not at 6 months, when abstinence rates fell to 9.1% for the intensive treatment group and 2.1% for the brief treatment group. Smoking treatment assignment did not significantly impact alcohol outcomes. Although intensive smoking treatment was associated with higher rates of short-term tobacco abstinence, other, perhaps more intensive, smoking interventions are needed to produce lasting smoking cessation in alcohol dependent smokers. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
98.
99.
Sallis James F.; Prochaska Judith J.; Taylor Wendell C.; Hill James O.; Geraci John C. 《Canadian Metallurgical Quarterly》1999,18(4):410
Psychological, biological, social, and physical environmental variables were examined for their association with physical activity of young people. A national sample of 1,504 parents and children in Grades 4–12 were interviewed by telephone. Twenty-two potential determinants were assessed along with an 11-item child physical activity index (α?=?.76). Hierarchical multiple regressions were conducted separately for 6 age–sex subgroups. Percentage of variance explained ranged from 18% for boys in Grades 4–6 to 59% for girls in Grades 10–12. Three variables had strong and consistent associations with the child physical activity index that generalized across subgroups: use of afternoon time for sports and physical activity, enjoyment of physical education, and family support for physical activity. These 3 variables should be targeted for change to promote physical activity in all groups of young people. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
100.
A pronounced degree of vertical imbalance in Australian fiscal federalism has placed increasing financial pressures on lower levels of government, including local government. This has led local government to seek additional ways of financing infrastructure development through developer charges. Due to the lower priority the Australian Bureau of Statistics has accorded local government statistics in recent years, it has been difficult to gauge the extent of use of developer charges as a revenue source. This paper attempts to review the evolution of developer contributions policy and describe the increasing importance of these charges in Australian local government, with special emphasis on New South Wales. 相似文献