全文获取类型
收费全文 | 3674篇 |
免费 | 179篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 32篇 |
综合类 | 9篇 |
化学工业 | 822篇 |
金属工艺 | 53篇 |
机械仪表 | 60篇 |
建筑科学 | 174篇 |
矿业工程 | 30篇 |
能源动力 | 105篇 |
轻工业 | 533篇 |
水利工程 | 92篇 |
石油天然气 | 11篇 |
无线电 | 272篇 |
一般工业技术 | 492篇 |
冶金工业 | 543篇 |
原子能技术 | 19篇 |
自动化技术 | 613篇 |
出版年
2024年 | 8篇 |
2023年 | 28篇 |
2022年 | 82篇 |
2021年 | 106篇 |
2020年 | 90篇 |
2019年 | 73篇 |
2018年 | 105篇 |
2017年 | 110篇 |
2016年 | 117篇 |
2015年 | 102篇 |
2014年 | 120篇 |
2013年 | 280篇 |
2012年 | 181篇 |
2011年 | 224篇 |
2010年 | 189篇 |
2009年 | 195篇 |
2008年 | 198篇 |
2007年 | 211篇 |
2006年 | 158篇 |
2005年 | 120篇 |
2004年 | 114篇 |
2003年 | 117篇 |
2002年 | 91篇 |
2001年 | 47篇 |
2000年 | 56篇 |
1999年 | 49篇 |
1998年 | 168篇 |
1997年 | 94篇 |
1996年 | 69篇 |
1995年 | 45篇 |
1994年 | 41篇 |
1993年 | 39篇 |
1992年 | 29篇 |
1991年 | 20篇 |
1990年 | 16篇 |
1989年 | 21篇 |
1988年 | 14篇 |
1987年 | 18篇 |
1986年 | 17篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 5篇 |
1981年 | 13篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1977年 | 9篇 |
1976年 | 7篇 |
1973年 | 3篇 |
1971年 | 3篇 |
排序方式: 共有3860条查询结果,搜索用时 15 毫秒
71.
Salvi D Gorman J Arredondo MT Vera-Muñoz C Ottaviano M Salvi S 《Computer methods and programs in biomedicine》2012,107(1):45-52
Personalized health (p-health) systems can contribute significantly to the sustainability of healthcare systems, though their feasibility is yet to be proven. One of the problems related to their development is the lack of well-established development tools for this domain. As the p-health paradigm is focused on patient self-management, big challenges arise around the design and implementation of patient systems. This paper presents a reference platform created for the development of these applications, and shows the advantages of its adoption in a complex project dealing with cardio-vascular diseases. 相似文献
72.
GPS coordinates are increasingly available as spatial references on population surveys in the developing world, where high-resolution address and street mapping are absent. This potentially offers opportunities to enhance national census data by spatial linkage with survey sources. The paper explores the use of GPS-referenced Demographic and Health Survey (DHS) data in combination with census data in Egypt and identifies errors in coordinate referencing. The study develops a practical approach to the measurement of spatial uncertainty in this situation and assessment of its impact on data linkage. The analysis specifically addresses the analytical implications at three different spatial scales and is internationally relevant to the handling of GPS-referenced DHS data in GIS. 相似文献
73.
Dania Esposito Andrea Margonelli Emanuela Pace Maria Teresa Giardi Cecilia Faraloni Giuseppe Torzillo Alba Zanini 《Microgravity science and technology》2006,18(3-4):215-218
Photosynthetic microorganisms are expected to be useful to maintain an oxygenic atmosphere and to provide biomass for astronauts in the International Space Station as well as in future long-term space flights. However, fluxes of complex ionizing radiation of various intensities and energies make space an extreme environment for the microorganisms, affecting their photosynthetic efficiency. To automatically monitor the photosynthetic Photosystem II (PSII) activity of microorganisms under space conditions an optical biosensor, which utilizes chlorophyll fluorescence as biological transduction system, was built; the PSII activity was monitored by the biosensor during balloon flights at stratospheric altitudes of about 40 km. The effect of space stress on quantum yield of PSII varied among the tested species depending on the growth light conditions at which they were exposed during the flights. 相似文献
74.
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
75.
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
76.
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
77.
Rodríguez José Ignacio Jiménez José Manuel Funes Francisco Javier García de Jalón Javier 《Multibody System Dynamics》2003,10(2):177-199
In this paper a prototype of a computer program for multi-bodysimulation based on the use of CORBA, Java and XML is presented. Thisprototype makes use of a recursive dynamic formalism which outperformsmany implementations based on global formulations. The prototypepresented has been implemented using distributed Object OrientedProgramming techniques. The definition of the multi-body system is donethrough a data file defined using XML (eXtendible Markup Language). Thisprototype implements a `simulation service' on a network of computers,following a client-server scheme. This `simulation service' can operatein two different ways: offering a remote simulation on the server, orproviding a Java compiled code for local simulation on the client. Thepaper describes the practical implementation of such a service. The useof recursive functions and OOP permits the implementation of ageneral-purpose simulation code, which is compact, clear, clean,re-usable and easy to maintain. Once this Java code is compiled, it isstored in less than 125 Kbytes (including the numerical integrators).The Java programming language is used in order to assure compatibilitybetween different platforms. Finally, practical examples which make useof this approach are shown. 相似文献
78.
J. L. Pons R. Ceres A. R. Jiménez L. Calderón J. M. Martin 《Journal of Intelligent and Robotic Systems》1997,18(3):277-287
The precise control of manipulators depends nonlinearly on the velocity of the motion as well as on manipulator configuration and commanded acceleration requiring complex control strategies. This paper presents a useful tool for identifying and quantifying nonlinear effects appearing during the motion of any manipulator, the Nonlinear Performance Index (npi). The npi takes into account not only the geometrical parameters defining the manipulator but also its structural dynamics through the use of inertial parameters like mass, inertia, centre of mass... The npi can be used in the design stage for analysing and reducing these undesirable nonlinear effects in any general motion or in the trajectory planning looking for paths along which more precise control is expected. The last part of the paper shows how this design optimisation and path planning has been applied to the Agribot, a fruit picking robot designed at the IAI. 相似文献
79.
80.
A simple method is presented for evaluating wall shear stresses from known flow histories in unsteady pipe flows. The method builds on previous work by Trikha, but has two important differences. One of these enables the method to be used with much larger integration time steps than are acceptable with Trikha’s method. The other, a general procedure for determining approximations to weighting functions, enables it to be used at indefinitely small times (high frequencies). The method is applicable to both laminar and turbulent flows. 相似文献