全文获取类型
收费全文 | 1467篇 |
免费 | 85篇 |
国内免费 | 139篇 |
出版年
2023年 | 18篇 |
2022年 | 29篇 |
2021年 | 27篇 |
2020年 | 30篇 |
2019年 | 42篇 |
2018年 | 48篇 |
2017年 | 42篇 |
2016年 | 45篇 |
2015年 | 37篇 |
2014年 | 42篇 |
2013年 | 167篇 |
2012年 | 64篇 |
2011年 | 72篇 |
2010年 | 40篇 |
2009年 | 42篇 |
2008年 | 46篇 |
2007年 | 76篇 |
2006年 | 54篇 |
2005年 | 48篇 |
2004年 | 34篇 |
2003年 | 38篇 |
2002年 | 35篇 |
2001年 | 57篇 |
2000年 | 49篇 |
1999年 | 49篇 |
1998年 | 21篇 |
1997年 | 12篇 |
1995年 | 12篇 |
1993年 | 12篇 |
1992年 | 14篇 |
1991年 | 24篇 |
1990年 | 28篇 |
1989年 | 17篇 |
1988年 | 13篇 |
1987年 | 16篇 |
1986年 | 19篇 |
1985年 | 19篇 |
1983年 | 11篇 |
1982年 | 12篇 |
1980年 | 9篇 |
1979年 | 10篇 |
1978年 | 14篇 |
1976年 | 12篇 |
1975年 | 13篇 |
1973年 | 15篇 |
1972年 | 11篇 |
1970年 | 13篇 |
1969年 | 11篇 |
1968年 | 14篇 |
1967年 | 10篇 |
排序方式: 共有1691条查询结果,搜索用时 15 毫秒
231.
Differences in the micromechanical properties of dendrites and interdendritic regions in superalloys
Statistical analysis of white-light interferometry (WLI) experiments performed on Ni-based single-crystal superalloys (SX) have revealed a different height distribution between the dendritic cores (DCs) and the interdendritic regions (IRs) of the polished samples. The micromechanical property difference is largely ascribed to the uneven distribution of the alloying elements. In this context, possible reasons for this difference are discussed by comparing with different experiment results obtained by previous researchers, and a proposal forecasting the hardness ratio of IRs/DCs is put forward. 相似文献
232.
Chuanji Gao Timm Rosburg Mingzhu Hou Bingbing Li Xin Xiao Chunyan Guo 《Cognitive, affective & behavioral neuroscience》2016,16(6):977-990
The effectiveness of retrieval practice for aiding long-term memory, referred to as the testing effect, has been widely demonstrated. However, the specific neurocognitive mechanisms underlying this phenomenon remain unclear. In the present study, we sought to explore the role of pre-retrieval processes at initial testing on later recognition performance by using event-related potentials (ERPs). Subjects studied two lists of words (Chinese characters) and then performed a recognition task or a source memory task, or restudied the word lists. At the end of the experiment, subjects received a final recognition test based on the remember–know paradigm. Behaviorally, initial testing (active retrieval) enhanced memory retention relative to restudying (passive retrieval). The retrieval mode at initial testing was indexed by more positive-going ERPs for unstudied items in the active-retrieval tasks than in passive retrieval from 300 to 900 ms. Follow-up analyses showed that the magnitude of the early ERP retrieval mode effect (300–500 ms) was predictive of the behavioral testing effect later on. In addition, the ERPs for correctly rejected new items during initial testing differed between the two active-retrieval tasks from 500 to 900 ms, and this ERP retrieval orientation effect predicted differential behavioral testing gains between the two active-retrieval conditions. Our findings confirm that initial testing promotes later retrieval relative to restudying, and they further suggest that adopting pre-retrieval processing in the forms of retrieval mode and retrieval orientation might contribute to these memory enhancements. 相似文献
233.
Computational algorithms of image processing were developed and evaluated to select, by motion detection, images of resting
artificial pigs and to segment the pigs (mixture of black and white pigs) from their background. Motion detection of the pigs
was implemented by detecting interframe differences of postural behavioral images. This algorithm combines the advantages
of likelihood ratio method and shading model method and shows a stable performance under noisy and dynamic illumination conditions.
Segmentation of the pigs from their background was implemented by employing multilevel thresholding and background reference
techniques. The algorithm automatically determines the number of thresholds needed and produces satisfactory segmentation
when both black and white pigs with different image intensities are present at the same time (the most complicated situation).
The reference background image is updated so that temporal changes in illumination and/or spatial changes of the pen condition
have little effect on the performance of image segmentation. The algorithm employs statistical models of the pigs and background
and Bayes hypothesis testing to obtain and update the exposed portion of the reference background. Linear filters were used
in this process for updating the parameters. These algorithms will serve as essential components for a novel, behavior-based,
interactive approach to assess and control thermal comfort of group-housed pigs, which is expected to result in enhanced animal
health and well-being. 相似文献
234.
235.
236.
237.
Jeremy P. Nahum Nadia Bruschweiler-Stern Alexandra M. Harrison Karlen Lyons-Ruth Alexander C. Morgan Louis Sander Daniel N. Stern Edward Z. Tronick 《Infant mental health journal》1998,19(3):315-319
A sequence of analytic sessions of a professional woman in her forties is used to illustrate the moving along process. The material shows a gradual change, where the patient's experience of her sense of agency is altered through a particular kind of interactive sequence. The example is intended to make it clear that the group's view of how change occurs is not strictly or primarily in terms of sudden changes, and that the problem of assessing moments of meeting as well as quantitative and qualitative shifts is one with which the group continues to struggle. © 1998 Michigan Association for Infant Mental Health 相似文献
238.
以习近平同志为核心的党中央倡导社会主义核心价值观入法入规,重新阐释了人类道德价值的内容、形式与机制。从伦理内容创新上看,社会主义核心价值观入法入规为传统德主刑辅思想注入新的伦理思想,刷新了“德”与“法”的内涵与外延;从伦理思维范式上看,社会主义核心价值观入法入规实现了德与法的深度融合;从伦理运行机制来看,社会主义核心价值观入法入规确立了将伦理价值与法律价值相结合的评价机制,激活了“德治”软实力与“法治”硬实力共同发力的动力机制。 相似文献
239.
240.