全文获取类型
收费全文 | 5207篇 |
免费 | 90篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 50篇 |
综合类 | 2篇 |
化学工业 | 982篇 |
金属工艺 | 67篇 |
机械仪表 | 108篇 |
建筑科学 | 230篇 |
矿业工程 | 16篇 |
能源动力 | 152篇 |
轻工业 | 372篇 |
水利工程 | 48篇 |
石油天然气 | 31篇 |
武器工业 | 1篇 |
无线电 | 302篇 |
一般工业技术 | 759篇 |
冶金工业 | 1475篇 |
原子能技术 | 54篇 |
自动化技术 | 655篇 |
出版年
2021年 | 44篇 |
2020年 | 39篇 |
2019年 | 59篇 |
2018年 | 65篇 |
2017年 | 70篇 |
2016年 | 60篇 |
2015年 | 61篇 |
2014年 | 80篇 |
2013年 | 284篇 |
2012年 | 175篇 |
2011年 | 250篇 |
2010年 | 150篇 |
2009年 | 191篇 |
2008年 | 228篇 |
2007年 | 219篇 |
2006年 | 220篇 |
2005年 | 193篇 |
2004年 | 153篇 |
2003年 | 148篇 |
2002年 | 130篇 |
2001年 | 81篇 |
2000年 | 106篇 |
1999年 | 97篇 |
1998年 | 121篇 |
1997年 | 99篇 |
1996年 | 93篇 |
1995年 | 89篇 |
1994年 | 93篇 |
1993年 | 100篇 |
1992年 | 97篇 |
1991年 | 68篇 |
1990年 | 75篇 |
1989年 | 72篇 |
1988年 | 65篇 |
1987年 | 84篇 |
1986年 | 80篇 |
1985年 | 89篇 |
1984年 | 73篇 |
1983年 | 71篇 |
1982年 | 78篇 |
1981年 | 67篇 |
1980年 | 51篇 |
1979年 | 53篇 |
1978年 | 64篇 |
1977年 | 56篇 |
1976年 | 53篇 |
1975年 | 58篇 |
1974年 | 38篇 |
1973年 | 52篇 |
1972年 | 35篇 |
排序方式: 共有5304条查询结果,搜索用时 31 毫秒
21.
Performed a correlational analysis of attendance records and grades in a 1st-yr psychology class. 103 undergraduates were informed that the attendance records would not affect their grades in the course. A positive correlation was found between attendance and final grades in the course. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
22.
An attempt is made to isolate the assumptions that make a connectionist approach to visual word recognition distinctive. These include the commitment to distributed representations, the claim that there is no distinction between lexical and nonlexical systems in the naming task, and the claim that it is possible to map from orthography to meaning without using localized representations. It is argued that merely demonstrating that a network model can perform these tasks is not sufficient and that a detailed theory of how the network performs its tasks must accompany the simulation, because a simulation is not equivalent to an explanation. It is argued that further progress requires detailed modeling and experimental study of the elementary processes assumed to be involved in networks and that it is premature to dismiss alternative models of lexical access such as serial search models. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
23.
The axisymmetric Laplace equation is solved numerically to extract contact-angle data for a flat liquid/vapor interface contacting a submerged hemispherical solid. The liquid/vapor interface is treated as a membrane, with a membrane tension equal to the surface energy of the liquid. By measuring the vertical displacement of the membrane and the projected contact area the membrane makes with the hemisphere, the contact angle and correspondingly the driving force for motion of the contact line can be measured. We show that characteristic receding and advancing contact angles can be obtained by measuring the contact radii formed upon initial contact between the interface and hemisphere and final contact just prior to detachment of the interface, respectively. Use of the technique is illustrated with a model experiment involving the contact of an air/water interface with a poly(methyl methacrylate) surface. 相似文献
24.
Blanchard Edward B.; Appelbaum Kenneth A.; Guarnieri Patricia; Neff Debra F.; Andrasik Frank; Jaccard James; Barron Kevin D. 《Canadian Metallurgical Quarterly》1988,56(3):427
Tension and vascular headache patients, initially treated with biofeedback and/or relaxation training in either a minimal therapist contact protocol (3 visits) or an intensive individual protocol (10 or 16 visits) were followed-up prospectively for 2 years. In the first study, for the first 6 months of follow-up, half of all patients continued to keep headache diaries and were seen monthly and the other half had only minimal contact. The results at 1-year follow-up, based on 4 weeks of daily headache diaries, revealed equally good maintenance from both treatment protocols and from both follow-up conditions. In Study 2, we found that patients remained improved over pretreatment baseline levels at the 2-year follow-up regardless of initial treatment intensity. Approximately three quarters of vascular patients who were initially improved at posttreatment remained improved at 2 years. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
25.
Greater use of psychological research and practice knowledge in the formulation of social policy is necessary to enhance the well-being of U.S. citizens and communities. Although historically there are instances in which psychological and social science research and practice have had a substantial influence on federal policy, for the most part the relationships among research, practice, and policy have been tenuous. Three cases in which research has substantively influenced policy over the past 80 years are reviewed: Keynesian economics, Head Start legislation, and the activities of conservative think tanks. Several recommendations are made for ways in which psychologists can enhance their influence in the policy arena, including communicating directly with policymakers regarding relevant policy findings and knowledge gleaned from practice; conducting interdisciplinary, multilevel research as well as evaluation research (including qualitative data drawn from practice settings); and networking among researchers, practitioners, policy advocates, and social action groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
26.
According to D. E. Broadbent's (1958) selective filter theory, people do not process unattended stimuli beyond the analysis of basic physical properties. This theory was later rejected on the basis of numerous findings that people identify irrelevant (and supposedly unattended) stimuli. A careful review of this evidence, however, reveals strong reasons to doubt that these irrelevant stimuli were in fact unattended. This review exposed a clear need for new experiments with tight control over the locus of attention. The authors present 5 such experiments using a priming paradigm. When steps were taken to ensure that irrelevant stimuli were not attended, these stimuli produced no priming effects. Hence, the authors found no evidence that unattended stimuli can be identified. The results support a modern version of Broadbent's selective theory, updated to reflect recent research advances. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
27.
Sausen Kenneth P.; Lovallo William R.; Pincomb Gwendolyn A.; Wilson Michael F. 《Canadian Metallurgical Quarterly》1992,11(1):55
Examined hemodynamic responses to systematic variations in occupational stress using ambulatory blood pressure monitors. Heart rate, systolic blood pressure, diastolic blood pressure, rate–pressure product, and mood states were measured before, during, and after low-stress (lecture) and high-stress (examination) work in 44 healthy White male medical students. The lecture day was characterized by stable patterns of cardiovascular activity across all 3 periods. Hemodynamic activity and reports of activation and distress were greater on the examination day than on the lecture day. Cardiovascular activity during the pre-examination period was as high as that seen during the examination period itself, indicating an anticipatory stress effect. Pressor activity decreased after the examination, although some residual chronotropic activity was seen. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
28.
Hemanshu Bhatt Kimberly Y. Donaldson D. P. H. Hasselman Kenneth Chyung Mark P. Taylor 《Journal of the American Ceramic Society》1991,74(6):1463-1465
A study concerning the effect of fiber orientation on the thermal conductivity of a uniaxial carbon-fiber-reinforced borosilicate glass was conducted. For thin specimens, and thick specimens with specimen sides cut parallel to the fiber direction, the dependence of thermal conductivity on fiber orientation showed excellent agreement with theoretical behavior predicted for a composite infinite in extent. In contrast, the thermal conductivity data for rectangular thick specimens fell well below the data for the thin and angled specimens. For fiber orientation of 45° and higher, at which the heat was directed toward the side of the specimen rather than across, the thermal conductivity values showed excellent agreement with theoretical behavior predicted for a finite composite strip with insulated sides. 相似文献
29.
This paper represents a portion of the evaluation of the use of Statistical Process Control within the realm of Conventional Computer Process Control. Various control charts commonly utilized in continuous processes are evaluated when subjected to process disturbances typical of continuous processes. The control charts considered are the Moving Average and Moving Range Chart combination, the Individual and Moving Range Chart combination, and the Exponentially Weighted moving Average Chart. The types of process disturbances considered are unit step and linear trend disturbances to the process average. The evaluation is based on the determination of the Average Run Lengths (ARLs) resulting from computer simulations. 相似文献
30.
Hopkinson bar techniques have played an important role in the study of high-rate deformation and fracture behavior of materials.
In the current work, a split Hopkinson pressure bar was developed for dynamic four-point bend fracture testing, referred to
as a “two-bar (incident and transmitted bars)/four-point” (2-bar/4-pt) bend test. To further understand some fundamental issues
regarding stress wave propagation in this 2-bar/4-pt bend testing system, dynamic fracture tests were performed in pulse-shaped
and unshaped pulse testing conditions. The effect of the pulse shaper on the incident pulse characteristics (rise time and
duration), specimen’s dynamic response (load and loading point displacement), crack initiation time and stress-state equilibrium
were investigated experimentally in the current work. The present results show that stress state equilibrium can be achieved
prior to fracture initiation in notched and precracked specimens. In the pulse-shaped bending test, the specimen is more likely
to attain stress-state equilibrium than in an unshaped incident pulse test. The crack initiation time was extended and the
time required for attaining stress equilibrium was reduced by pulse shaping due to the tailored incident pulse having a longer
rise time, which ensures that stress equilibrium is achieved prior to crack initiation.
This article is based on a presentation made in the symposium entitled “Dynamic Behavior of Materials,” which occurred during
the TMS Annual Meeting and Exhibition, February 25–March 1, 2007 in Orlando, Florida, under the auspices of The Minerals,
Metals and Materials Society, TMS Structural Materials Division, and TMS/ASM Mechanical Behavior of Materials Committee. 相似文献