首页 | 官方网站   微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   401篇
  免费   5篇
  国内免费   1篇
工业技术   407篇
  2024年   2篇
  2023年   3篇
  2022年   2篇
  2021年   8篇
  2020年   5篇
  2018年   4篇
  2017年   7篇
  2016年   7篇
  2015年   3篇
  2014年   3篇
  2013年   19篇
  2012年   11篇
  2011年   16篇
  2010年   9篇
  2009年   16篇
  2008年   11篇
  2007年   25篇
  2006年   10篇
  2005年   7篇
  2004年   9篇
  2003年   7篇
  2002年   12篇
  2001年   12篇
  2000年   11篇
  1999年   9篇
  1998年   27篇
  1997年   17篇
  1996年   14篇
  1995年   12篇
  1994年   11篇
  1993年   18篇
  1992年   5篇
  1991年   2篇
  1990年   9篇
  1989年   5篇
  1988年   6篇
  1986年   5篇
  1985年   6篇
  1984年   5篇
  1983年   2篇
  1982年   2篇
  1981年   3篇
  1979年   2篇
  1978年   5篇
  1976年   6篇
  1974年   2篇
  1973年   3篇
  1969年   1篇
  1965年   2篇
  1964年   1篇
排序方式: 共有407条查询结果,搜索用时 15 毫秒
21.
Although several measures of obsessive-compulsive (OC) symptoms exist, most are limited in that they are not consistent with the most recent empirical findings on the nature and dimensional structure of obsessions and compulsions. In the present research, the authors developed and evaluated a measure called the Dimensional Obsessive-Compulsive Scale (DOCS) to address limitations of existing OC symptom measures. The DOCS is a 20-item measure that assesses the four dimensions of OC symptoms most reliably replicated in previous structural research. Factorial validity of the DOCS was supported by exploratory and confirmatory factor analyses of 3 samples, including individuals with OC disorder, those with other anxiety disorders, and nonclinical individuals. Scores on the DOCS displayed good performance on indices of reliability and validity, as well as sensitivity to treatment and diagnostic sensitivity, and hold promise as a measure of OC symptoms in clinical and research settings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
22.
Molecular dynamics has been used to simulate the uniaxial compression of single crystal silicon nanospheres using the Tersoff potential. The resulting yield behavior is shown to vary with changes in temperature, sphere size, and crystallographic orientation with respect to the loading direction. Only compression along the [1 0 0] crystallographic direction resulted in the formation of the β-Sn phase. A temperature dependent hardening response is observed in all orientations independent of the β-Sn phase transformation. Dislocation activity is detected at elevated temperatures in the largest sphere indicating a critical temperature and size for nucleation. Consequences of these dislocations to simulating strength properties at the nanoscale are discussed.  相似文献   
23.
The current Internet can only provide the best-effort services. By growing the Internet and its applications, new services with different requirements are developed. The differentiated services (Diffserv) [S. Blake, M. Carlson, E. Davies, Z. Wang, W. Weiss, An Architecture for Differentiated Services, IETF RFC 2475, 1998; K. Nichols, V. Jacobson, L. Zhang, A Two-bit Differentiated Services Architecture for the Internet, IETF RFC 2638, July 1999; T. Li, Y. Rekhter, A Provider Architecture for Differentiated Services and Traffic Engineering (PASTE), IETF RFC 2430, October 1998] is a scalable model for providing end-to-end quality of services. A Diffserv router consists of different components including classifier, meter, marker, dropper, shaper and scheduler. In this paper, we use the benefits of the fuzzy logic controller to design a fuzzy based traffic conditioner for Internet differentiated services. Our proposed model consists of three major parts: a fuzzy meter/marker (FM), a fuzzy active queue management (FAQM) algorithm and a fuzzy scheduler (FS). The proposed FM used to measure and mark the input traffic is based on the single rate three colors meter (srTCM) mechanism [J. Heinane, et al., A Single Rate Three Color Marker, RFC 2697, September 1999]. The FM meters an IP packet stream and marks its packets GREEN, YELLOW, or RED. The proposed FAQM is a fuzzy implementation of the well-known BLUE active queue management (AQM) algorithm [W. Feng, D. Kandlur, D. Saha, K. Shin, BLUE: A New Class of Active Queue Management Algorithms U. Michigan CSE-TR-387-99, April 1999]. To achieve a good throughput and reasonable packet loss ratio, the proposed FAQM mechanism employs a fuzzy logic controller. The third part of the proposed fuzzy traffic conditioner is FS. It is based on the traditional weighted fair queue (WFQ) mechanism [A. Demers, S. Keshav, S. Shenker, Analysis and simulation of a fair queueing algorithm, in: SIGCOMM Symposium on Communications Architectures and Protocols, Austin, Texas, September 1989, pp. 1–12] that tunes the weight of each queue by a fuzzy logic controller. To evaluate the performance of the proposed model, we developed a software in C++ environment to simulate it. Different network topologies with different traffic parameters were performed. The simulation results easily helped us to judge the merit of the proposed FM, FAQM and FS because of their remarkable performance over the traditional non-fuzzy mechanisms.  相似文献   
24.
A sexual size dimorphism usually occurs when size-dependent reproductive advantages exist in only one sex. Studies on Japanese medaka, Oryzias latipes, have demonstrated reproductive size advantages in females but not in males, even though males and females are similar in body size. We conducted mate-choice and mate-copying tests in which a female could first associate with, then mate with, either a large (>/=1 sd+X standard length) or a small male (相似文献   
25.
26.
377 high school students read and were immediately tested on a prose passage, scored their own tests, then estimated how well they would have scored if tested after a delay of 1, 8, or 15 days. Data for these 3 hypothetical delay periods provided a "predicted forgetting function." An actual forgetting function was also obtained by administering a retention test with comparable questions after 1, 8, or 15 days. Within each of the 9 groups defined by the hypothetical and actual delay factors, there were 2 strategy groups—Ss who could only read the passage and those who took notes. After the immediate test, Ss in each strategy group estimated how well they would have scored if they had employed the alternate strategy. Results indicate a difference between predicted and actual forgetting, with Ss expecting a larger amount of forgetting than actually occurred. Note taking had a small facilitative effect on learning. However, Ss failed to predict positive effects of note taking. Ss' expectations about effects of other strategies were also examined, and implications regarding metamemory and study skills are discussed. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
27.
Conducted 2 experiments to examine 192 8-, 11-, and 14-yr-old children's incidental learning with the central and incidental pictorial elements in each stimulus (a) presented as separate entities (standard condition), (b) depicted together in an action relation (2 types-weak action and strong action), or (c) depicted together in a static relation. Following a learning task in which attention to a single element in each stimulus was required, incidental learning was measured by having the S indicate the incidental feature associated with each central component. Results show that incidental learning was higher with the action than the standard materials, but the developmental trend in these scores was little affected by pictorial integration. While extending the generality of previous incidental learning results, these data contrast with evidence showing an increase with age in the effects of action portrayal on intentional learning of pictorial associations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
28.
This paper outlines a computer program especially tailored to the task of deriving explicit equations of motion for structures with point-connected substructures. The special purpose program is written in FORTRAN and is designed for performing the specific algebraic operations encountered in the derivation of explicit equations of motion. The derivation is by the Lagrangian approach. Using an orderly kinematical procedure and a discretization and/or truncation scheme, it is possible to write the kinetic and potential energy of each substructure in a compact vector-matrix form. Then, if each element of the matrices and vectors encountered in the kinetic and potential energy is a known algebraic expression, the computer program performs the necessary operations to evaluate the kinetic and potential energy of the system explicitly. Lagrange's equations for small motions about equilibrium can be deduced directly from the explicit form of the system kinetic and potential energy.  相似文献   
29.
The authors report 2 experiments in which they examined age differences in working memory tasks involving complex item manipulation (i.e., letter-number sequencing). In Experiment 1, age differences on tasks involving item manipulation were not greater than age differences on tasks requiring recall of items in the order in which they appeared, suggesting that older adults do not have difficulty with item manipulation per se. In Experiment 2, slower presentation rates increased age differences in item manipulation spans, although age differences at the fastest rate may be attributed to differences in strategy use. In both experiments, age differences were largest when participants were most likely to be remembering familiar sequences, suggesting that older adults may have difficulties dampening the representations of such sequences once they are activated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
30.
We study the relative performance of various methods for aligning noisy one-dimensional signals. No knowledge of the shape of the misaligned signals is assumed. We simulate signals corrupted by both additive noise and timing jitter noise which are similar in complexity to nose-to-nose oscilloscope calibration signals collected at NIST. In one method, we estimate the relative shift of two signals as the difference of their estimated centroids, We present a new adaptive algorithm for centroid estimation. We also estimate relative shifts from three different implementations of cross-correlation analysis. In a complete implementation, for N signals, relative shifts are estimated from all N(N-1)/2 distinct pairs of signals. In a naive implementation, relative shifts are estimated from just (N-1) pairs of signals. In an iterative adaptive implementation, we estimate the relative shift of each signal with respect to a template signal which, at each iteration, is equated to the signal average of the aligned signals. In simulation experiments, 100 misaligned signals are generated. For all noise levels, the complete cross-correlation method yields the most accurate estimates of the relative shifts. The relative performance of the other methods depends on the noise levels  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号