全文获取类型
收费全文 | 3074篇 |
免费 | 130篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 29篇 |
综合类 | 9篇 |
化学工业 | 565篇 |
金属工艺 | 51篇 |
机械仪表 | 50篇 |
建筑科学 | 127篇 |
矿业工程 | 28篇 |
能源动力 | 95篇 |
轻工业 | 369篇 |
水利工程 | 30篇 |
石油天然气 | 7篇 |
无线电 | 298篇 |
一般工业技术 | 450篇 |
冶金工业 | 551篇 |
原子能技术 | 11篇 |
自动化技术 | 541篇 |
出版年
2024年 | 5篇 |
2023年 | 19篇 |
2022年 | 26篇 |
2021年 | 48篇 |
2020年 | 61篇 |
2019年 | 51篇 |
2018年 | 73篇 |
2017年 | 85篇 |
2016年 | 90篇 |
2015年 | 72篇 |
2014年 | 88篇 |
2013年 | 212篇 |
2012年 | 132篇 |
2011年 | 174篇 |
2010年 | 160篇 |
2009年 | 160篇 |
2008年 | 174篇 |
2007年 | 169篇 |
2006年 | 132篇 |
2005年 | 94篇 |
2004年 | 98篇 |
2003年 | 105篇 |
2002年 | 77篇 |
2001年 | 39篇 |
2000年 | 53篇 |
1999年 | 51篇 |
1998年 | 179篇 |
1997年 | 106篇 |
1996年 | 74篇 |
1995年 | 52篇 |
1994年 | 43篇 |
1993年 | 44篇 |
1992年 | 32篇 |
1991年 | 22篇 |
1990年 | 17篇 |
1989年 | 23篇 |
1988年 | 22篇 |
1987年 | 19篇 |
1986年 | 16篇 |
1985年 | 17篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 5篇 |
1981年 | 14篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 7篇 |
1976年 | 10篇 |
1973年 | 6篇 |
排序方式: 共有3211条查询结果,搜索用时 15 毫秒
41.
This paper introduces and motivates ADL, a new formal notation for the specification of the temporal and functional behaviour
of concurrent processes. ADL is tailored to be directly compatible with the DORIS design method. It combines a graphical Activity State-Machine (ASM) notation and a model-based Activity Functional Behaviour (AFB) notation. The abstract syntax, and static and dynamic semantics for the ASM notation are given, the dynamic semantics
being given proof-theoretically in many-sorted logic extended with the RTL ‘occurrence’ relation, Θ, and the ERTL ‘holding’ relation, Φ. ADL is used to specify a small network, and proofs are given of its timeliness and safety properties.
Received November 1998 / Accepted in revised form May 2000 相似文献
42.
There's no doubt that personal information can be valuable to companies. People are willing to give up information about themselves not because they're stupid or because they're being tricked by evil corporations, but because it can sometimes be in their best interests to do so. From this perspective, the important questions are how users can provide or limit access to that information, what benefits they might receive in exchange for a bit of information, and how they perceive the value of those benefits. 相似文献
43.
Jim Spohrer Laura C. Anderson Norman J. Pass Tryg Ager Daniel Gruhl 《Journal of Grid Computing》2008,6(3):313-324
This paper is a first exploration of the relationship between service science and Grid computing. Service science is the study
of value co-creation interactions among entities, known as service systems. Within the emerging service science community,
service is often defined as the application of competences (resources) for the benefit of another. Grid computing is the study
of resource sharing among entities, known as virtual organizations, which solve complex business, societal, scientific, and
engineering problems. Within the Grid computing community, service is sometimes defined as protocols plus behavior. Both Grid
computing and service science are connecting academic, industry, government, and volunteer sector collaborators on a range
of projects including eScience, healthcare, environmental sustainability, and more. This paper compares and contrasts the
notions of resource, entity, service, interaction, and success criteria for the two areas of study. In conclusion, new areas
for collaborative inquiry are proposed. 相似文献
44.
Brick masons and mason tenders report a high prevalence of work-related musculoskeletal disorders (WMSDs), many of which can be prevented with changes in materials, work equipment or work practices. To explore the use of "best practices" in the masonry industry, NIOSH organized a 2-day meeting of masonry stakeholders. Attendees included 30 industry representatives, 5 health and safety researchers, 4 health/safety specialists, 2 ergonomic consultants, and 2 representatives of state workers' compensation programs. Small groups discussed ergonomic interventions currently utilized in the masonry industry, including factors affecting intervention implementation and ways to promote diffusion of interventions. Meeting participants also identified various barriers to intervention implementation, including business considerations, quality concerns, design issues, supply problems, jobsite conditions and management practices that can slow or limit intervention diffusion. To be successful, future diffusion efforts must not only raise awareness of available solutions but also address these practical concerns. 相似文献
45.
This research investigates the use of patterns in designing adaptable, flexible hypermedia applications. While patterns are particularly applicable to software design, they can also be used to assist designers of other types of applications. We have developed a method (APHID) that guides a hypermedia creator through the analysis and design process. The method ensures that good design principles are followed, both for the hypermedia application and for the interface that presents the hypermedia application. Our method uses a concept map, constraints, and patterns (instructional and presentation) to support partial automation for creating hypermedia applications. We also present a prototype software system that uses the APHID method to create instructional hypermedia applications semi-automatically. The applications created using APHID are tailored to specific types of learners. We conclude with a claim that this approach is applicable not just to instructional hypermedia, but to the larger problem of generating adaptable interfaces. 相似文献
46.
Much effort has gone into the recognition of the human right to water. Without doubt, this milestone influences governance and decision making processes at many scales so it is essential now to shift the discussion from the legal and conceptual framework to practice. Along this line, the article proposes a methodology for monitoring access to water in rural areas using the framework of this human right. The practicality of the approach is demonstrated by a case study carried out in Nicaragua. Different criteria of the right to water were included in surveys and structured interviews that were conducted in rural households and water committees, respectively. A discussion analyzes the advantages and challenges of using this framework. Finally, the approach provides elements for policy making that can be used by different stakeholders in the development and human rights sectors. 相似文献
47.
A Piecewise Grey System Model for Study the Effects of Anthropogenic Activities on Karst Hydrological Processes 总被引:2,自引:0,他引:2
Yonghong Hao Bibo Cao Xiang Chen Jian Yin Ronglin Sun Tian-Chyi Jim Yeh 《Water Resources Management》2013,27(5):1207-1220
Sustainable groundwater development must rely on a good understanding of hydrological processes, especially under effects of anthropogenic activities. This paper develops a piecewise analysis based on grey system model for study effects of anthropogenic activities on hydrological processes. The time series of precipitation and spring discharge were segmented into three time periods depending on whether variations are due to climate variation: the predevelopment stage, the transition stage, and the new equilibrium stage. Then we modeled hydrological process of the predevelopment stage and new equilibrium stage by the grey system model. By comparing the model results, we can quantify the effects of human activities on hydrological processes. We applied the model to Liulin Springs China. The results indicated that the hydraulic response time of the spring discharge to precipitation from the predevelopment stage to the new equilibrium stage, ranges from less than 1 year to up to 4 years. The results revealed that human activities slow the groundwater flow. GM (1,N) models of Liulin Springs discharge showed that the driving coefficients of precipitation to the spring discharge decreased from 0.012272 in the predevelopment stage to 0.007753 in the new equilibrium stage, which means that groundwater recharge ability has reduced about 36.82 %. Human activities in Liulin Springs have drastically changed the groundwater system. Piecewise grey system model is a robust method for hydrological process simulation. 相似文献
48.
Richard Ashley David Blackwood Nicki Souter Sarah Hendry Jim Moir Judith Dunkerley John Davies David Butler Andrew Cook Jim Conlin Martin Squibbs Andrew Britton Peter Goldie 《Canadian Metallurgical Quarterly》2005,131(2):206-215
The study presented is an example of the assessment of the relative sustainability of either option for disposal of domestic sanitary waste, either via the toilet or via the solid waste route. This required an evaluation of the total (social, economic, environmental, and technical) benefit/cost of implementing and adopting the alternative routes and an assessment of public responsiveness to encouragement to change sanitary waste disposal practices. It illustrates how, even for an apparently straightforward either/or question, the assessment of relative sustainability is complex and the amount of data needed to quantify sustainability indicators is prodigious. The study also provides an appraisal of the effectiveness of public campaigns to reduce waterborne disposal. Important information regarding public attitude and behavior in relation to wastewater systems has been acquired and lessons for ways of encouraging behavioral change to more sustainable ways of living have been gleaned. 相似文献
49.
Neiss Michelle B.; Stevenson Jim; Sedikides Constantine; Kumashiro Madoka; Finkel Eli J.; Rusbult Caryl E. 《Canadian Metallurgical Quarterly》2005,89(4):593
Complementary approaches examined the relations among executive self, self-esteem, and negative affectivity. A cross-sectional (N = 4,242) and a longitudinal (N = 158) study established that self-esteem mediated the relation between executive self and negative affectivity. A 3rd study (N = 878 twin pairs) replicated this pattern and examined genetic and environmental influences underlying all 3 phenotypes. Covariation among the 3 phenotypes reflected largely common genetic influences, although unique genetic effects explained variability in both executive self and negative affectivity. Executive self was influenced by shared environmental influences unique from those affecting self-esteem and negative affectivity. Nonshared environmental influences accounted for the majority of variance in each construct and were primarily unique to each. The unique genetic and nonshared environmental influences support the proposition that the executive self, self-esteem, and negative affectivity capture distinct and important differences between people. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
50.
M. Dolores Jiménez-Gamero Juan Luis Moreno-Rebollo Juan M. Muñoz-Pichardo Ana M. Muñoz-Reyes 《TEST》2005,14(2):515-542
One of the areas of Statistics in which the influence analysis has been widely studied is the multiple linear regression model.
Nevertheless, the influence diagnostics proposed in this context cannot be applied to regression in complex survey, under
randomized inference, since the i.i.d. case does not incorporate any probability weighting or population structure, such as
clustering, stratification or measures of size into the analysis.
In this paper we introduce some influence diagnostics in regression in complex survey. They are built on the conditional bias
concept (Moreno-Rebollo et al., 1999). We emphasize the similarities and differences of the proposed measures with respect
to the existing ones for the i.i.d. case.
Research partly supported by the Spanish MCYT grant BFM2001-3844 and Spanish MEC grant MTM2004-0111433. 相似文献