全文获取类型
收费全文 | 5943篇 |
免费 | 292篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 80篇 |
综合类 | 9篇 |
化学工业 | 1023篇 |
金属工艺 | 69篇 |
机械仪表 | 97篇 |
建筑科学 | 210篇 |
矿业工程 | 6篇 |
能源动力 | 174篇 |
轻工业 | 365篇 |
水利工程 | 54篇 |
石油天然气 | 41篇 |
无线电 | 587篇 |
一般工业技术 | 1360篇 |
冶金工业 | 1097篇 |
原子能技术 | 22篇 |
自动化技术 | 1049篇 |
出版年
2024年 | 13篇 |
2023年 | 59篇 |
2022年 | 96篇 |
2021年 | 150篇 |
2020年 | 119篇 |
2019年 | 127篇 |
2018年 | 134篇 |
2017年 | 151篇 |
2016年 | 173篇 |
2015年 | 144篇 |
2014年 | 204篇 |
2013年 | 356篇 |
2012年 | 334篇 |
2011年 | 413篇 |
2010年 | 321篇 |
2009年 | 309篇 |
2008年 | 349篇 |
2007年 | 280篇 |
2006年 | 249篇 |
2005年 | 231篇 |
2004年 | 168篇 |
2003年 | 157篇 |
2002年 | 160篇 |
2001年 | 83篇 |
2000年 | 77篇 |
1999年 | 90篇 |
1998年 | 159篇 |
1997年 | 153篇 |
1996年 | 106篇 |
1995年 | 69篇 |
1994年 | 84篇 |
1993年 | 76篇 |
1992年 | 53篇 |
1991年 | 28篇 |
1990年 | 37篇 |
1989年 | 32篇 |
1988年 | 27篇 |
1987年 | 40篇 |
1986年 | 20篇 |
1985年 | 47篇 |
1984年 | 28篇 |
1983年 | 21篇 |
1982年 | 27篇 |
1981年 | 42篇 |
1980年 | 23篇 |
1979年 | 23篇 |
1978年 | 19篇 |
1977年 | 27篇 |
1976年 | 48篇 |
1975年 | 18篇 |
排序方式: 共有6243条查询结果,搜索用时 0 毫秒
31.
Cross Susan E.; Gore Jonathan S.; Morris Michael L. 《Canadian Metallurgical Quarterly》2003,85(5):933
Examination of the assumptions underlying consistency perspectives in social and personality psychology reveals that they are based on an independent, individualistic view of the self. If the self is constructed as relational or interdependent with others, consistency may be less important in social behavior and well-being. Using a variety of measures of well-being, the studies showed that there is a weaker relation between consistency and well-being for individuals with a highly relational self-construal than for those with a low relational self-construal. Study 3 examined the association between the self-construal, consistency, authenticity, and well-being. These findings reveal the importance of a cultural analysis of theories of the self, personality, and well-being for further theory development. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
32.
33.
Utilitarian and economic theories of deterrence hold that the relation of the penalty to the misdeed should be irrelevant. In 5 experiments using hypothetical cases, judgments of penalties depended on whether this relation was in kind (IK) or out of kind (OK). When victims were identifiable, IK penalties were higher than OK and preferred to OK. Subjects seemed to confuse penalties and compensation. When there were no identifiable victims (e.g., environmental damage), IK penalties were preferred, but OK penalties were higher. Here, OK judgments were more uncertain, and subjects preferred to err on the side of overpunishing. The results can be explained in terms of overgeneralization of usually useful heuristics. Alternative hypotheses concerning aggression and scale compatibility are rejected. The findings have implications for the setting of penalties in legal cases (e.g., the Exxon Valdez) and for lay theories of punishment in nonlegal settings. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
34.
Responsiveness of self-reported and objective measures of disease severity in carpal tunnel syndrome
JN Katz RH Gelberman EA Wright RA Lew MH Liang 《Canadian Metallurgical Quarterly》1994,32(11):1127-1133
Responsiveness, the ability to detect meaningful clinical change, is a critical attribute of instruments used to evaluate outcomes of treatments. The authors hypothesized that self-administered symptom severity and functional status questionnaires are more responsive to clinical improvement after carpal tunnel release than traditional physical examination measures of strength and sensibility. Data were obtained from a randomized clinical trial of endoscopic versus open carpal tunnel release conducted in four university medical centers. Patients were evaluated before surgery and 3 months after surgery. Seventy-four patients indicating that they were more than 80% satisfied with the results of surgery were assumed to have clinically meaningful improvement and were the focus of the analysis. Evaluations included questionnaires assessing symptom severity, functional status, and activities of daily living as well as measurement of grip, pinch, and abductor pollicus brevis strength, and 2-point discrimination and Semmes-Weinstein pressure sensibility. Responsiveness was calculated with the standardized response mean (mean change/standard deviation of change) as well as the effect size (mean change/standard deviation of baseline values). The symptom severity scale was four times as responsive, and the functional status and activities of daily living scales were twice as responsive, as the measures of strength and sensibility. Self-administered symptom severity and functional status scales are much more responsive to clinical improvement than measures of neuromuscular impairment and should severe as primary outcomes in clinical studies of therapy for carpal tunnel syndrome. 相似文献
35.
A new technique for understanding the organization of complex circuits in the vertebrate brain, scanning laser photostimulation, is described. This approach is based on the photolysis of a caged form of the excitatory neurotransmitter glutamate. Computer-controlled photostimulation and whole cell recording in brain slices allow the construction of detailed maps of the position, strength, sign and number of inputs converging on a single postsynaptic neuron. Scanning laser photostimulation offers many advantages over current techniques: spatial resolution is superb, fibers of passage are not activated, and thousands of presynaptic locations can be stimulated. This review describes the technique of photostimulation, outlines the instrumentation, necessary to implement it, and discusses the interpretation of photostimulation-derived data. Several examples of applications, ranging from mapping circuits in the mammalian visual cortex to determining receptor distributions on single neurons are considered. Although still in its early stages, scanning laser photostimulation offers neuroscientists a powerful tool for determining the organization and function of local brain circuits. 相似文献
36.
Thomas G. OConnor Jonathan A. Dantzig 《Metallurgical and Materials Transactions B》1994,25(3):443-457
A three-dimensional mathematical model has been developed to compute the thermomechanical state in the mold of thin-slab continuous
casters. The thin-slab mold differs from those used in conventional slab casters in that the upper portion of the broad side
walls defines a funnel-shaped chamber which allows the nozzle to be submerged into the liquid metal. The chamber converges
with distance down the mold, reducing to the rectangular cross section of the finished casting near the mold exit. The new
mold, along with casting speeds up to 6 m/min, allows slabs to be cast 50–60 mm thick, compared with 150 to 350 mm in conventional
continuous slab casting. However, the mold shape and high casting speed lead to higher mold temperatures and shorter mold
life than are found in conventional slab casters. In this article, we develop mathematical models of the process to determine
the role of various process parameters in determining the mold life. Finite-element analysis is used to determine the temperatures
in the mold and cast slab, and these data are then used in an elastic-viscoplastic analysis to investigate the deformation
of the mold wall in service. Cyclic inelastic strains up to 1.75 Pct are found in a region below the meniscus along the funnel
edge. These large strains result from the combination of locally high temperatures coupled with geometric restraint of the
mold. The deformation leads to short mold life because of thermal fatigue cracking of the mold. The computed locations and
time to failure of the mold in fatigue agree very well with observations of the appearance of mold surface cracks in an operating
caster. The models are also used to develop an improved mold design.
Formerly Research Assistant, Department of Mechanical and Industrial Engineering, University of Illinois, Urbana, IL 相似文献
37.
Both Soviet and American youth show a great concern about the possible effects of nuclear war, with heavy media users in both countries more optimistic, but the relation was stronger among Soviet students. 相似文献
38.
A sensing strategy for the reverse engineering of machined parts 总被引:1,自引:0,他引:1
The reverse engineering of machined parts requires sensing an existing part and producing a design (and perhaps a manufacturing process) for it. We have developed a reverse engineering system that has proven effective with a set of machined parts. This paper describes the system, presents some results, and discusses strategy for a new system.This work was supported by ARPA under ARO grant number DAAH04-93-G-0420, DARPA grant N00014-91-J-4123, NSF grant CDA 9024721, and a University of Utah Research Committee grant. All opinions, findings, conclusions or recommendations expressed in this document are those of the authors and do not necessarily reflect the views of the sponsoring agencies. 相似文献
39.
THE IMPORTANCE OF NEUTRAL EXAMPLES FOR LEARNING SENTIMENT 总被引:2,自引:0,他引:2
Most research on learning to identify sentiment ignores "neutral" examples, learning only from examples of significant (positive or negative) polarity. We show that it is crucial to use neutral examples in learning polarity for a variety of reasons. Learning from negative and positive examples alone will not permit accurate classification of neutral examples. Moreover, the use of neutral training examples in learning facilitates better distinction between positive and negative examples. 相似文献
40.
Barch Deanna M.; Cohen Jonathan D.; Servan-Schreiber David; Steingard Sandra; Steinhauer Stuart S.; van Kammen Daniel P. 《Canadian Metallurgical Quarterly》1996,105(4):592
Semantic priming in word pronunciation was examined at 5 stimulus onset asynchronies (SOAs) in 75 medicated and 25 unmedicated people with schizophrenia (SCZ) and in 10 depressed and 28 normal controls. At SOAs 相似文献