全文获取类型
收费全文 | 5698篇 |
免费 | 153篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 82篇 |
综合类 | 5篇 |
化学工业 | 1111篇 |
金属工艺 | 114篇 |
机械仪表 | 76篇 |
建筑科学 | 316篇 |
矿业工程 | 7篇 |
能源动力 | 163篇 |
轻工业 | 377篇 |
水利工程 | 44篇 |
石油天然气 | 113篇 |
武器工业 | 1篇 |
无线电 | 386篇 |
一般工业技术 | 873篇 |
冶金工业 | 1399篇 |
原子能技术 | 50篇 |
自动化技术 | 745篇 |
出版年
2021年 | 63篇 |
2020年 | 58篇 |
2019年 | 59篇 |
2018年 | 70篇 |
2017年 | 62篇 |
2016年 | 78篇 |
2015年 | 83篇 |
2014年 | 85篇 |
2013年 | 347篇 |
2012年 | 204篇 |
2011年 | 232篇 |
2010年 | 167篇 |
2009年 | 178篇 |
2008年 | 223篇 |
2007年 | 227篇 |
2006年 | 193篇 |
2005年 | 187篇 |
2004年 | 167篇 |
2003年 | 154篇 |
2002年 | 162篇 |
2001年 | 90篇 |
2000年 | 97篇 |
1999年 | 108篇 |
1998年 | 78篇 |
1997年 | 87篇 |
1996年 | 109篇 |
1995年 | 79篇 |
1994年 | 76篇 |
1993年 | 89篇 |
1992年 | 85篇 |
1991年 | 62篇 |
1990年 | 76篇 |
1989年 | 89篇 |
1988年 | 77篇 |
1987年 | 88篇 |
1986年 | 80篇 |
1985年 | 101篇 |
1984年 | 111篇 |
1983年 | 81篇 |
1982年 | 74篇 |
1981年 | 85篇 |
1980年 | 62篇 |
1979年 | 96篇 |
1978年 | 68篇 |
1977年 | 75篇 |
1976年 | 55篇 |
1975年 | 65篇 |
1974年 | 57篇 |
1973年 | 74篇 |
1972年 | 53篇 |
排序方式: 共有5862条查询结果,搜索用时 0 毫秒
31.
94 smokers (mean age 39 yrs) in a 6-wk behavioral smoking-cessation program were administered weekly questionnaires on their use of major program recommendations and other quitting strategies throughout treatment. An "affect-regulation" coping inventory was administered at the beginning and end of treatment. Adequate adherence was reported for most recommendations. Although a composite measure of adherence did not predict quitting success, adherence and coping assessments were associated with maintenance of treatment gains. Short-term maintenance was associated with an extensive affect-regulation repertoire and use of stimulus control strategies; long-term maintenance was associated with consistent self-monitoring of smoking during treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
32.
Edward G. Goetz 《Journal of Urban Affairs》1991,13(3):337-351
ABSTRACT: Many analysts argue that important structural conditions exist that discourage city governments from engaging in redistributive policy, especially programs that create direct costs for private developers. Labeled the limited city argument, this logic concludes that only cities with sufficient levels of economic and fiscal well-being can afford to impose upon private developers to meet social needs. Using survey data from 133 cities with populations over 100,000, this paper examines land use regulations that impose obligations or restrictions on the private sector to promote low income housing. The data suggest that the limited city argument is only part of the explanation. The use of regulatory housing policy is also correlated with measures of need and low income housing advocacy. 相似文献
33.
Liaqat A. Khan Edward A. Wicklein E. C. Teixeira 《Canadian Metallurgical Quarterly》2006,132(7):741-746
A three-dimensional (3D) computational fluid dynamics (CFD) model of a contact tank is presented in this paper. The model results are compared against 3D velocities and flow through curve (FTC) data, representing a tracer concentration profile, from a 1:8 scale physical model. The objective is to demonstrate that CFD models can simulate both the FTC and the 3D velocity field quite well. Simultaneous validation of velocities and FTC is important in ascertaining the predictive capabilities of CFD models, as physical model studies indicate that different baffle arrangements can lead to similar FTCs. Therefore, a good prediction of only FTC, as presented in previous 3D CFD model studies, does not necessarily imply a correct simulation of the flow field. 相似文献
34.
Cell phones are a pervasive new communication technology, especially among college students. This paper examines college students’ cell phone usage from a behavioral and psychological perspective. Utilizing both qualitative (focus groups) and quantitative (survey) approaches, the study suggests these individuals use the devices for a variety of purposes: to help them feel safe, for financial benefits, to manage time efficiently, to keep in touch with friends and family members, et al. The degree to which the individuals are dependent on the cell phones and what they view as the negatives of their utilization are also examined. The findings suggest people have various feelings and attitudes toward cell phone usage. This study serves as a foundation on which future studies will be built. 相似文献
35.
Royzman Edward B.; Cassidy Kimberly Wright; Baron Jonathan 《Canadian Metallurgical Quarterly》2003,7(1):38
This article reviews the evidence and theory pertaining to a form of perspective-taking failure--a difficulty in setting aside the privileged information that one knows to be unavailable to another party. The authors argue that this bias (epistemic egocentrism, or EE) is a general feature of human cognition and has been tapped by 2 independent and largely uncommunicating research traditions: the theory-of-mind tradition in developmental psychology and, with more sensitive probes, the "heuristics and biases" tradition in the psychology of human judgment. This article sets the stage for facilitating communication between these traditions as well as for the recognition of EE's breadth and potential interdisciplinary significance. The authors propose a life-span account and a tentative taxonomy of EE; and they highlight the interdisciplinary significance of EE by discussing its implications for normative ethics. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
36.
In industrial fluid cokers the feedstock, consisting of heavy bituminous hydrocarbons, is atomized with steam and injected into a hot fluidized bed of coke. Good and uniform contact of the liquid droplets with the solid particles is required to provide heat for the cracking reactions while minimizing mass transfer effects. Experiments in a pilot plant coker have suggested that the initial particle/liquid mixing, in the spray jet, is rather poor. Experiments in a X-ray scanner showed that liquid droplets and entrained particles accumulate just below the tip of the jet plume to form agglomerates.An experimental technique was used to quantitatively determine the quality of mixing with a variety of nozzle configurations including several novel designs. By improving spray stability, redistributing liquid droplets to the solids-rich region of the jet and increasing the surface area of the gas-liquid jet-fluidized bed interface, liquid/solid contact is improved. 相似文献
37.
This paper reports off-lattice Monte Carlo simulations of highly-branched comb homopolymers weakly adsorbed on a flat, featureless surface showing only covolume and dispersion interactions with the adsorbate. A minimal coarse-grained model, described by hard spheres connected by harmonic springs, was employed. The interaction energy of the adsorbed combs and linear chains is first discussed as a function of the molecular mass and of the number of beads in contact with the surface. The molecular size is then investigated as a function of backbone length and branching density at a fixed arm size. The apparent swelling exponents of the adsorbed combs are larger than those of the corresponding linear chains, and much larger than that of the free molecules. This result indicates a surface-induced stiffening of the comb backbone, further studied through the persistence length lpers. It is found that lpers increases upon adsorption over the free-molecule value, more so the larger is the branching density. Finally, the thickness of the adsorbed layer, the surface-induced molecular anisotropy and the molecular aspect ratio are investigated as a function of branching density and molecular mass. 相似文献
38.
Maria E. Nadal Edward A. Early Will Weber Robert Bousquet 《Color research and application》2008,33(2):94-99
The NIST 0:45 reflectometer measures the spectral reflectance factor at an influx angle of 0° and an efflux angle of 45° of colored, nonfluorescent specimens at room temperature, with widths ranging from 3 to 10 cm and heights from 3 to 20 cm and with an uncertainty of less than 0.5 in color difference units. Published in 2008 by John Wiley & Sons, Inc. Col Res Appl, 33, 94–99, 2008 相似文献
39.
Sets of color tiles are available from the National Institute of Standards and Technology calibrated using the NIST 0:45 Reflectometer. The uncertainties associated with the measured values for the color tiles are an indispensable component of the calibration report that accompanies these tiles. A systematic, analytical approach developed previously was applied to the particular case of the reference instrument and color tile set, taking into account the operation and characteristics of the instrument and the spectral properties of the set. The primary sources of uncertainty were identified, and the resulting uncertainties in the color space values L*, a*, and b* were determined. In general, the uncertainties are lowest for those color tiles whose reflectance factors are nearly constant with wavelength. Published in 2008 by John Wiley & Sons, Inc. Col Res Appl, 33, 100–107, 2008 相似文献
40.
Color‐vision deficiency is a relatively common genetic condition, which often leads to the obstruction of necessary information in colored images. It is important to minimize such inconvenient effects in communication using colored images from a universal design perspective. The universal design principle stipulates that all environments and products should be usable by all people, regardless of age, physical attributes, and ability. This article proposes a method to detect color combinations in a given image that would confuse color dichromats, and suggests a way in which to modify them to make the image easily distinguishable for both normal and dichromatic observers. Confusing color combinations were detected based on a color‐difference calculation using simulations of how the color would appear to dichromats. The confusing colors were then modified based on the minimization of an evaluation function, which was defined as the sum of the degree of confusion and the degree of color change from the original image. Several colored images obtained by the proposed method were compared with the originals by red–green dichromatic observers who judged them to be clearer, thereby confirming that the proposed method was effective for color rendering for universal design. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 203–211, 2008 相似文献