全文获取类型
收费全文 | 1230篇 |
免费 | 55篇 |
专业分类
电工技术 | 7篇 |
综合类 | 1篇 |
化学工业 | 232篇 |
金属工艺 | 5篇 |
机械仪表 | 13篇 |
建筑科学 | 61篇 |
矿业工程 | 2篇 |
能源动力 | 22篇 |
轻工业 | 163篇 |
水利工程 | 21篇 |
石油天然气 | 3篇 |
无线电 | 55篇 |
一般工业技术 | 187篇 |
冶金工业 | 379篇 |
原子能技术 | 3篇 |
自动化技术 | 131篇 |
出版年
2023年 | 17篇 |
2022年 | 11篇 |
2021年 | 45篇 |
2020年 | 27篇 |
2019年 | 28篇 |
2018年 | 28篇 |
2017年 | 30篇 |
2016年 | 29篇 |
2015年 | 23篇 |
2014年 | 31篇 |
2013年 | 79篇 |
2012年 | 51篇 |
2011年 | 91篇 |
2010年 | 68篇 |
2009年 | 65篇 |
2008年 | 83篇 |
2007年 | 81篇 |
2006年 | 67篇 |
2005年 | 50篇 |
2004年 | 44篇 |
2003年 | 30篇 |
2002年 | 39篇 |
2001年 | 25篇 |
2000年 | 23篇 |
1999年 | 20篇 |
1998年 | 20篇 |
1997年 | 20篇 |
1996年 | 16篇 |
1995年 | 7篇 |
1994年 | 18篇 |
1993年 | 9篇 |
1992年 | 9篇 |
1991年 | 3篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 10篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 8篇 |
1984年 | 12篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1976年 | 2篇 |
1975年 | 5篇 |
1973年 | 2篇 |
1958年 | 2篇 |
排序方式: 共有1285条查询结果,搜索用时 15 毫秒
21.
Maxine M. Denniston Nancy D. Brener Laura Kann Danice K. Eaton Timothy McManus Tonja M. Kyle Alice M. Roberts Katherine H. Flint James G. Ross 《Computers in human behavior》2010
The Youth Risk Behavior Surveillance System (YRBSS) monitors priority health-risk behaviors among US high school students. To better understand the ramifications of changing the YRBSS from paper-and-pencil to Web administration, in 2008 the Centers for Disease Control and Prevention conducted a study comparing these two modes of administration. Eighty-five schools in 15 states agreed to participate in the study. Within each participating school, four classrooms of students in grades 9 or 10 were randomly assigned to complete the Youth Risk Behavior Survey questionnaire in one of four conditions (in-class paper-and-pencil, in-class Web without programmed skip patterns, in-class Web with programmed skip patterns, and “on your own” Web without programmed skip patterns). Findings included less missing data for the paper-and-pencil condition (1.5% vs. 5.3%, 4.4%, 6.4%; p < .001), less perceived privacy and anonymity among respondents for the in-class Web conditions, and a lower response rate for the “on your own” Web condition than for in-class administration by either mode (28.0% vs. 91.2%, 90.1%, 91.4%; p < .001). Although Web administration might be useful for some surveys, these findings do not favor the use of a Web survey for the YRBSS. 相似文献
22.
Remote sensing of phytoplankton community composition along the northeast coast of the United States
Xiaoju Pan Antonio Mannino Katherine C. Filippino 《Remote sensing of environment》2011,115(12):3731-3747
Satellite imagery has proven to be a powerful tool for measuring chlorophyll a in surface waters. While this provides an estimate of total phytoplankton biomass, it does not distinguish between phytoplankton groups, many of which have functional differences and therefore affect biogeochemical cycles differently. Phytoplankton pigment analysis has been used to quantify a wide range of photosynthetic and accessory pigments, and chemotaxonomic analysis (e.g. CHEMTAX) has been used to successfully quantify functional taxonomic groups in nature based on pigment distributions. Here, we combine CHEMTAX analysis with satellite-derived distributions of specific phytoplankton pigments to describe the distributions of particular components of the phytoplankton community in the northeast coast of the United States from space. The spatial and seasonal variations in phytoplankton community structure elucidated through satellite remote sensing methods generally agreed with observations of abundance estimates of cell counts. Diatoms were generally the most abundant phytoplankton in this region, especially during Winter-Spring and in the inner shelf, but phytoplankton populations shifted to increasing abundance of other taxa during Summer, especially offshore. While still preliminary, satellite-derived taxa-specific information with proper regional controls holds promise for providing information on phytoplankton abundance to a taxonomic group level which would greatly improve our understanding of the impacts of human activity and climate change on ecosystems. 相似文献
23.
Katherine T. Moorhead Jonathan V. HillJ. Geoffrey Chase Christopher E. HannJennifer M. Scotter Malina K. StorerZoltan H. Endre 《Computer methods and programs in biomedicine》2011,101(2):173-182
This paper compares three methods for estimating renal function, as tested in rats. Acute renal failure (ARF) was induced via a 60-min bilateral renal artery clamp in 8 Sprague-Dawley rats and renal function was monitored for 1 week post-surgery. A two-compartment model was developed for estimating glomerular filtration via a bolus injection of a radio-labelled inulin tracer, and was compared with an estimated creatinine clearance method, modified using the Cockcroft-Gault equation for rats. These two methods were compared with selected ion flow tube-mass spectrometry (SIFT-MS) monitoring of breath analytes. Determination of renal function via SIFT-MS is desirable since results are available non-invasively and in real time. Relative decreases in renal function show very good correlation between all 3 methods (R2 = 0.84, 0.91 and 0.72 for breath-inulin, inulin-creatinine, and breath-creatinine correlations, respectively), and indicate good promise for fast, non-invasive determination of renal function via breath testing. 相似文献
24.
Maria Leet Socolof Lori Kincaid Colleen Mizuki Gloria Schuldt Katherine Hart Dipti Singh 《Journal of the Society for Information Display》2001,9(1):45-50
Decision rules have been developed and applied to the bills of materials of a color cathode‐ray tube (CRT) and a liquid‐crystal‐display (LCD) desktop monitor to determine which product and process materials will be evaluated in an environmental life‐cycle assessment. Materials of significant mass, of technological importance, and of potential environmental impact are targeted. The list of materials identified are those for which life‐cycle inventory data will be obtained for the materials extraction and materials processing life‐cycle stages of a CRT and an LCD. Additionally, materials identified will also be used to represent life‐cycle impact in terms of resource consumption, as well as surrogates for occupational health impacts. 相似文献
25.
Ahn TS Al-Kaysi RO Müller AM Wentz KM Bardeen CJ 《The Review of scientific instruments》2007,78(8):086105
A new method is presented for analyzing the effects of self-absorption on photoluminescence integrating sphere quantum yield measurements. Both the observed quantum yield and luminescence spectrum are used to determine the self-absorption probability, taking into account both the initial emission and subsequent absorption and reemission processes. The analysis is experimentally validated using the model system of the laser dye perylene red dispersed in a polymer film. This approach represents an improvement over previous methods that tend to overestimate the true quantum yield, especially in cases with high sample absorbance or quantum yield values. 相似文献
26.
Green CS Sugarman MA Medford K Klobusicky E Daphne Bavelier 《Computers in human behavior》2012,28(3):984-994
There is now a substantial body of work demonstrating that action video game experience results in enhancements in a wide variety of perceptual skills. More recently, several groups have also demonstrated improvements in abilities that are more cognitive in nature, in particular, the ability to efficiently switch between tasks. In a series of four experiments, we add to this body of work, demonstrating that the action video game player advantage is not exclusively due to an ability to map manual responses onto arbitrary buttons, but rather generalizes to vocal responses, is not restricted to tasks that are perceptual in nature (e.g. respond to a physical dimension of the stimulus such as its color), but generalizes to more cognitive tasks (e.g. is a number odd or even), and is present whether the switch requires a goal-switch or only a motor switch. Finally, a training study establishes that the relationship between the reduction in switch cost and action game playing is causal. 相似文献
27.
Hicks Thomas V.; Leitenberg Harold; Barlow David H.; Gorman Jack M.; Shear M. Katherine; Woods Scott W. 《Canadian Metallurgical Quarterly》2005,73(3):506
The authors explored the prognostic value of 3 different types of catastrophic cognitions in the treatment of panic disorder with and without mild-to-moderate agoraphobia using a sample of 143 participants who received either cognitive-behavioral therapy (CBT) or imipramine in a randomized controlled trial. Stronger fears of social catastrophes both prior to and following treatment with CBT or imipramine were associated with a poorer outcome. In contrast, cognitions involving physical or mental catastrophes were unrelated to outcome, regardless of whether these thoughts were measured prior to or following treatment. These findings are consistent with the notion that although the intensity of physical catastrophe cognitions may best discriminate between panic disorder and other anxiety disorders, it is the intensity of social catastrophe cognitions that is most closely tied to success in treating this disorder. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
28.
Wilk Christopher M.; Gold James M.; McMahon Robert P.; Humber Katherine; Iannone Virginia N.; Buchanan Robert W. 《Canadian Metallurgical Quarterly》2005,19(6):778
Cognitive impairment is well documented in schizophrenia, though some reports have been interpreted to suggest that it is possible to have schizophrenia without neuropsychological impairment. The authors tested this by comparing the neuropsychological profiles of closely matched patients with schizophrenia and healthy comparison participants. Sixty-four patients with schizophrenia and 64 healthy comparison cases, matched to within 3 Full-Scale IQ points, were tested using the Wechsler Adult Intelligence Scale (3rd ed.; D. Wechsler, 1997b) and the Wechsler Memory Scale (3rd ed.; D. Wechsler, 1997c). Neuropsychological profiles for these groups were markedly different, with the group of patients with schizophrenia exhibiting performance deficits in memory and speeded visual processing but superior verbal comprehension and perceptual organization relative to the group of healthy comparison participants matched on Full-Scale IQ. Thus, scoring in the normal range does not preclude neuropsychological abnormality in schizophrenia, confirming that neuropsychological impairment is a core feature of the illness. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
29.
Olson Ingrid R.; Jiang Yuhong; Moore Katherine Sledge 《Canadian Metallurgical Quarterly》2005,31(5):889
The ability to remember visual stimuli over a short delay period is limited by the small capacity of visual working memory (VWM). Here the authors investigate the role of learning in enhancing VWM. Participants saw 2 spatial arrays separated by a 1-s interval. The 2 arrays were identical except for 1 location. Participants had to detect the difference. Unknown to the participants, some spatial arrays would repeat once every dozen trials or so for up to 32 repetitions. Spatial VWM performance increased significantly when the same location changed across display repetitions, but not at all when different locations changed from one display repetition to another. The authors suggest that a major role of learning in VWM is to mediate which information gets retained, rather than to directly increase VWM capacity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
30.
Roope Kaivola Katherine Kohatsu 《International Journal on Software Tools for Technology Transfer (STTT)》2003,4(3):323-334
We examine the challenges presented by large-scale formal verification of industrial-size circuits, based on our experiences
in verifying the class of all micro-operations executing on the floating-point division and square root unit of the Intel
IA-32 Pentium?4 microprocessor. The verification methodology is based on combining human-guided mechanised theorem-proving
with low-level steps verified by fully automated model-checking. A key observation in the work is the need to explicitly address
the issues of proof design and proof engineering, i.e., the process of creating proofs and the craft of structuring and formulating
them, as concerns on their own right.
Published online: 19 November 2002 相似文献