全文获取类型
收费全文 | 1576篇 |
免费 | 72篇 |
专业分类
1648篇 |
出版年
2023年 | 13篇 |
2021年 | 25篇 |
2020年 | 36篇 |
2019年 | 25篇 |
2018年 | 51篇 |
2017年 | 52篇 |
2016年 | 52篇 |
2015年 | 34篇 |
2014年 | 46篇 |
2013年 | 180篇 |
2012年 | 92篇 |
2011年 | 69篇 |
2010年 | 52篇 |
2009年 | 45篇 |
2008年 | 45篇 |
2007年 | 62篇 |
2006年 | 46篇 |
2005年 | 58篇 |
2004年 | 46篇 |
2003年 | 30篇 |
2002年 | 39篇 |
2001年 | 29篇 |
2000年 | 30篇 |
1999年 | 36篇 |
1998年 | 15篇 |
1997年 | 11篇 |
1996年 | 12篇 |
1995年 | 16篇 |
1994年 | 17篇 |
1993年 | 17篇 |
1992年 | 20篇 |
1991年 | 21篇 |
1990年 | 15篇 |
1989年 | 15篇 |
1988年 | 14篇 |
1987年 | 20篇 |
1986年 | 13篇 |
1985年 | 14篇 |
1982年 | 12篇 |
1980年 | 12篇 |
1979年 | 19篇 |
1976年 | 11篇 |
1974年 | 16篇 |
1973年 | 16篇 |
1972年 | 10篇 |
1971年 | 14篇 |
1969年 | 12篇 |
1968年 | 12篇 |
1967年 | 12篇 |
1966年 | 12篇 |
排序方式: 共有1648条查询结果,搜索用时 0 毫秒
231.
232.
233.
C. Taylor 《The Journal of Ethics》1999,3(1):73-87
In this article I examine an example of sympathy -- the actions of one woman who rescued Jews during their persecution in Nazi Europe. I argue that this woman's account of her actions here suggests that sympathy is a primitive response to the suffering of another. By primitive here I mean: first, that these responses are immediate and unthinking; and second, that these responses are explanatorily basic, that they cannot be explained in terms of some more fundamental feature of human nature -- such as some particular desire or sentiment that we possess. My conclusion is then that our sympathetic responses are themselves partially constitutive of our conception of what is to be a human being. 相似文献
234.
Abstract Although life event research has burgeoned in recent years, little attention has been paid to the prevalence of events among the elderly or their relationship to psychological well-being. This paper presents data from a three-wave longitudinal study of community elderly in Aberdeen. Negative life events were highly prevalent among both survivors [N=349) and non-survivors [N=108], but the relatively small differences between the groups indicate that attrition does not seriously affect longitudinal findings. Longitudinal analysis of survivors' data was performed using LISREL and yielded a model with a goodness of fit index of 0.918, demonstrating a close fit between the data and the model. The model parameters indicate that those in poor psychological state were more likely to report serious non-health events than health events, although the latter were more likely than the former to result in a decline in psychological well-being, even after prior psychological state was taken into account. While elderly people with low social integration experienced more severe reactions to life events in the short term than those with high social integration, there were no significant long term effects, even for those reporting highly stressful events. There was no evidence of a sub-group of elderly people lacked into a cycle of serious life events. However life events were not random occurrences; serious health events were more often reported by those with low education while women and those in lower social classes were more likely to report serious non-health events. Overall, long term disruption, directly attributable to life events, was minimal when viewed within the context of the community elderly's stable psychological state. 相似文献
235.
Tripping and falling is a serious health problem for older citizens due to the high medical costs incurred and the high mortality rates precipitated mostly by hip fractures that do not heal well. Current falls prevention technology encompasses a broad range of interventions; both passive (e.g., safer environments, hip protectors) and active (e.g., sensor-based fall detectors) which attempt to reduce the effects of tripping and falling. However the majority of these interventions minimizes the impact of falls and do not directly reduce the risk of falling. This paper investigates the prediction of gait parameters related to foot-to-ground clearance height during the leg swing phase which have been physically associated with tripping and falling risk in the elderly. The objective is to predict parameters of foot trajectory several walking cycles in advance so that anticipated low foot clearance could be addressed early with more volitional countermeasures, e.g., slowing down or stopping. In this primer study, foot kinematics was recorded with a highly accurate motion capture system for 10 healthy adults (25-32 years) and 11 older adults (65-82 years) with a history of falls who each performed treadmill walking for at least 10 min. Vertical foot displacement during the swing phase has three characteristic inflection points and we used these peak values and their normalized time as the target prediction values. These target variables were paired with features extracted from the corresponding foot acceleration signal (obtained through double differentiation). A generalized regression neural network (GRNN) was used to independently predict the gait variables over a prediction horizon (number of gait cycles ahead) of 1-10 gait cycles. It was found that the GRNN attained 0.32-1.10 cm prediction errors in the peak variables and 2-8% errors in the prediction of normalized peak times, with slightly better accuracies in the healthy group compared to elderly fallers. Prediction accuracy decreased linearly (best fit) at a slow rate with increasing prediction horizon ranging from 0.03 to 0.11 cm per step for peak displacement variables and 0.34 × 10(-3) - 1.81 × 10(-3)% per step for normalized peak time variables. Further time series analysis of the target gait variable revealed high autocorrelations in the faller group indicating the presence of cyclic patterns in elderly walking strategies compared to almost random walking patterns in the healthy group. The results are promising because the technique can be extended to portable sensor-based devices which measure foot accelerations to predict the onset of risky foot clearance, thus leading to a more effective falls prevention technology. 相似文献
236.
237.
238.
239.
240.
It is proposed that runner's high is mediated by increased endorphin release as induced by placebo responses arising from subjective expectancies and setting. 相似文献