全文获取类型
收费全文 | 760篇 |
免费 | 30篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 231篇 |
金属工艺 | 8篇 |
机械仪表 | 11篇 |
建筑科学 | 51篇 |
矿业工程 | 1篇 |
能源动力 | 37篇 |
轻工业 | 81篇 |
水利工程 | 2篇 |
石油天然气 | 3篇 |
无线电 | 28篇 |
一般工业技术 | 115篇 |
冶金工业 | 160篇 |
原子能技术 | 2篇 |
自动化技术 | 53篇 |
出版年
2023年 | 5篇 |
2022年 | 30篇 |
2021年 | 30篇 |
2020年 | 15篇 |
2019年 | 5篇 |
2018年 | 14篇 |
2017年 | 14篇 |
2016年 | 24篇 |
2015年 | 16篇 |
2014年 | 21篇 |
2013年 | 55篇 |
2012年 | 37篇 |
2011年 | 37篇 |
2010年 | 33篇 |
2009年 | 30篇 |
2008年 | 42篇 |
2007年 | 39篇 |
2006年 | 31篇 |
2005年 | 25篇 |
2004年 | 23篇 |
2003年 | 14篇 |
2002年 | 25篇 |
2001年 | 12篇 |
1999年 | 8篇 |
1998年 | 15篇 |
1997年 | 11篇 |
1996年 | 18篇 |
1995年 | 9篇 |
1994年 | 13篇 |
1993年 | 11篇 |
1992年 | 9篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 11篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 7篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1975年 | 8篇 |
1974年 | 6篇 |
1972年 | 3篇 |
1968年 | 3篇 |
1966年 | 3篇 |
排序方式: 共有790条查询结果,搜索用时 0 毫秒
11.
Colin?WilbornEmail author Jacqueline?Beckham Bill?Campbell Travis?Harvey Melyn?Galbreath Paul?La Bounty Erika?Nassar Jennifer?Wismann Richard?Kreider 《Journal of the International Society of Sports Nutrition》2005,2(2):4-31
Obesity and its associated disorders are a growing epidemic across the world. Many genetic, physiological, and behavioral
factors play a role in the etiology of obesity. Diet and exercise are known to play a valuable role in the treatment and prevention
of obesity and associated disorders such as hypertension, heart disease, and diabetes. Therefore, the purpose of this review
is to examine the prevalence, etiology, consequences, and treatment of obesity. 相似文献
12.
Multilayer hybrid visualizations to support 3D GIS 总被引:3,自引:0,他引:3
In this paper, we present a unique hybrid visualization system for spatial data. Although some existing 3D GIS systems offer 2D views they are typically isolated from the 3D view in that they are presented in a separate window. Our system is a novel hybrid 2D/3D approach that seamlessly integrates 2D and 3D views of the same data. In our interface, multiple layers of information are continuously transformed between the 2D and 3D modes under the control of the user, directly over a base terrain. In this way, our prototype system is able to depict 2D and 3D views within the same window. This has advantages, since 2D and 3D visualizations can each be easier to interpret in different contexts.In this work we develop this concept of a hybrid visualization by presenting a comprehensive set of capabilities within our distinctive system. These include new facilities such as: hybrid landmark, 3D point, and chart layers, the grouping of multiple hybrid layers, layer painting, the merging of layer controls and consistent zooming functionality. 相似文献
13.
Identifying discriminating variables between teachers who fully integrate computers and teachers with limited integration 总被引:1,自引:0,他引:1
Julie Mueller Eileen Wood Teena Willoughby Craig Ross Jacqueline Specht 《Computers & Education》2008,51(4):1523-1537
Given the prevalence of computers in education today, it is critical to understand teachers’ perspectives regarding computer integration in their classrooms. The current study surveyed a random sample of a heterogeneous group of 185 elementary and 204 secondary teachers in order to provide a comprehensive summary of teacher characteristics and variables that best discriminate between teachers who integrate computers and those who do not. Discriminant Function Analysis indicated seven variables for elementary teachers and six for secondary teachers (accounting for 74% and 68% of the variance, respectively) that discriminated between high and low integrators. Variables included positive teaching experiences with computers; teacher’s comfort with computers; beliefs supporting the use of computers as an instructional tool; training; motivation; support; and teaching efficacy. Implications for support of computer integration in the classroom are discussed. 相似文献
14.
Jacqueline G. Ord 《AI & Society》1995,9(1):80-90
Value in the British National Health Service have shifted away from patient care towards financial control. However, in the quest for efficiency, huge amounts of NHS money have been wasted on computer system which failed. In this paper, I draw on a case study to explore some of the ethical issues which underlie this kind of waste of resources. Issues include the gap between public pronouncements and personal experience, the chaos of which lies behind the facade of rationality, and the systematic silencing of people, usually women, who question the viability of computer systems which are created for private gain rather than public service. 相似文献
15.
Bennett JC Krishnamoorthy V Liu S Grout RW Hawkes ER Chen JH Shepherd J Pascucci V Bremer PT 《IEEE transactions on visualization and computer graphics》2011,17(12):1822-1831
We present a new framework for feature-based statistical analysis of large-scale scientific data and demonstrate its effectiveness by analyzing features from Direct Numerical Simulations (DNS) of turbulent combustion. Turbulent flows are ubiquitous and account for transport and mixing processes in combustion, astrophysics, fusion, and climate modeling among other disciplines. They are also characterized by coherent structure or organized motion, i.e. nonlocal entities whose geometrical features can directly impact molecular mixing and reactive processes. While traditional multi-point statistics provide correlative information, they lack nonlocal structural information, and hence, fail to provide mechanistic causality information between organized fluid motion and mixing and reactive processes. Hence, it is of great interest to capture and track flow features and their statistics together with their correlation with relevant scalar quantities, e.g. temperature or species concentrations. In our approach we encode the set of all possible flow features by pre-computing merge trees augmented with attributes, such as statistical moments of various scalar fields, e.g. temperature, as well as length-scales computed via spectral analysis. The computation is performed in an efficient streaming manner in a pre-processing step and results in a collection of meta-data that is orders of magnitude smaller than the original simulation data. This meta-data is sufficient to support a fully flexible and interactive analysis of the features, allowing for arbitrary thresholds, providing per-feature statistics, and creating various global diagnostics such as Cumulative Density Functions (CDFs), histograms, or time-series. We combine the analysis with a rendering of the features in a linked-view browser that enables scientists to interactively explore, visualize, and analyze the equivalent of one terabyte of simulation data. We highlight the utility of this new framework for combustion science; however, it is applicable to many other science domains. 相似文献
16.
Summary In the present paper, the evolution of publication activity and citation impact in Brazil is studied for the period 1991-2003.
Besides the analysis of trends in publication and citation patterns and of national publication profiles, an attempt is made
to find statistical evidences of the relation between international co-authorship and both research profile and citation impact
in the Latin American region. Despite similarities and strong co-publication links with the other countries in the region,
Brazil has nonetheless a specific research profile, and forms the largest potential in the region. 相似文献
17.
The authors surveyed 347 public sector employees on 4 measurement occasions to investigate the conceptual distinctiveness of the psychological contract and perceived organizational support (POS) and how they are associated over time. Results support the distinctiveness of the 2 concepts. In terms of their interrelationships over time, by drawing on psychological contract theory the authors found little support for a reciprocal relationship between POS and psychological contract fulfillment. Under an alternative set of hypotheses, by drawing on organizational support theory and by separating psychological contract fulfillment into its 2 components (perceived employer obligations and inducements), the authors found that perceived employer inducements were positively related to POS, which, in turn, was negatively related to perceived employer obligations. The results suggest that POS and the components of psychological contract fulfillment are more important in predicting organizational citizenship behavior than psychological contract fulfillment. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
18.
Wall Jacqueline Remondet; Busch Monique; Koch Steven M.; Alexander Gina; Minnich Heike; Jackson-Walker Susan 《Canadian Metallurgical Quarterly》2005,2(1):39
Questions are often raised regarding the effectiveness and value of treatment programs for children and families. Recently, programs have been increasingly held accountable for services offered. In response, the member agencies of IARCCA have developed a comprehensive outcome measurement program. This article describes the project, focusing on the conditions that led to its inception and how the measurement plan was developed. In addition, the article includes information on the selection of personnel, measurement instruments, and methods and on the process of data collection. Summary results are provided, including how these results are utilized to improve services. Finally, the continued expansion and future directions of the Outcome Project are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
19.
The dimensionality of the original Job Diagnostic Survey (JDS) and a revision were investigated. Factor analyses of two data sets identified six dimensions underlying the original JDS. Five of the factors correspond to the pattern expected for the JDS items; the sixth was identified as a measurement artifact. Five of the JDS items were subsequently rewritten to eliminate the artifact. The revised survey was administered to employees of a printing company (N?=?134) and the a priori five-factor solution was obtained with no artifact factor. Scale–factor correlations were also computed. The resulting coefficients suggest that the revised JDS scales are measuring their underlying constructs with reasonable accuracy. As a result of the measurement artifact in the original JDS, it is recommended that the revised JDS should be used in future research concerned with task characteristics. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
20.
Lucas Bayons María Jos Guerra-Fernndez Fernando Hinostroza Ximena Bez-Matus Jacqueline Vsquez-Navarrete Luciana I. Gallo Sergio Parra Agustín D. Martínez Arlek Gonzlez-Jamett Fernando D. Marengo Ana M. Crdenas 《International journal of molecular sciences》2022,23(18)
Gain-of-function mutations of dynamin-2, a mechano-GTPase that remodels membrane and actin filaments, cause centronuclear myopathy (CNM), a congenital disease that mainly affects skeletal muscle tissue. Among these mutations, the variants p.A618T and p.S619L lead to a gain of function and cause a severe neonatal phenotype. By using total internal reflection fluorescence microscopy (TIRFM) in immortalized human myoblasts expressing the pH-sensitive fluorescent protein (pHluorin) fused to the insulin-responsive aminopeptidase IRAP as a reporter of the GLUT4 vesicle trafficking, we measured single pHluorin signals to investigate how p.A618T and p.S619L mutations influence exocytosis. We show here that both dynamin-2 mutations significantly reduced the number and durations of pHluorin signals induced by 10 μM ionomycin, indicating that in addition to impairing exocytosis, they also affect the fusion pore dynamics. These mutations also disrupt the formation of actin filaments, a process that reportedly favors exocytosis. This altered exocytosis might importantly disturb the plasmalemma expression of functional proteins such as the glucose transporter GLUT4 in skeletal muscle cells, impacting the physiology of the skeletal muscle tissue and contributing to the CNM disease. 相似文献