全文获取类型
收费全文 | 270篇 |
免费 | 10篇 |
专业分类
各国政治 | 22篇 |
工人农民 | 7篇 |
世界政治 | 65篇 |
外交国际关系 | 9篇 |
法律 | 101篇 |
中国政治 | 3篇 |
政治理论 | 72篇 |
综合类 | 1篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 3篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 12篇 |
2016年 | 8篇 |
2015年 | 10篇 |
2014年 | 6篇 |
2013年 | 34篇 |
2012年 | 8篇 |
2011年 | 8篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 8篇 |
2007年 | 12篇 |
2006年 | 9篇 |
2005年 | 15篇 |
2004年 | 10篇 |
2003年 | 16篇 |
2002年 | 7篇 |
2001年 | 9篇 |
2000年 | 20篇 |
1999年 | 10篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1975年 | 2篇 |
1966年 | 1篇 |
排序方式: 共有280条查询结果,搜索用时 31 毫秒
21.
22.
23.
Carsten A. Holz 《当代中国》2002,11(32):515-538
China's industrial state-owned enterprises (SOEs) have seen a secular decline in profitability throughout the reform period. Barry Naughton argues that this decline was in large part due to a decline in monopoly rents as competition with enterprises in other ownership forms increased. Fan Gang and Woo Wing-Thye, on the other hand, contend that profitability declined across all sectors independent of the degree of competition, and that excessive labor remuneration accounts for the broad decline in SOE profitability. Testing the two hypotheses with aggregate sectoral and provincial data from the mid-1980s to the late-1990s, neither appears convincing. Yet at closer inspection these are not competing hypotheses. The two causes affect overall profitability through different channels. Competition and labor remuneration have a highly significant impact on intermediate profitability measures that take the two channels into account separately. Together they explain most of the variation in overall profitability. 相似文献
24.
25.
26.
27.
28.
29.
30.
The human teeth are a valuable source of information concerning identification and age calculation in forensic sciences. Dental treatment often causes permanent alteration of the teeth, which is visible on radiographs. The correlation of prosthetic restorations, root canal fillings and periodontal bone loss with chronological age has not yet been used for determining the completed 18th year of life in teenagers and young adults, e. g. for legal and anthropological purposes. The aim of this study was to determine whether the evaluation of such findings on radiographs correlates with the chronological age in teenagers and young adults. MATERIAL AND METHODS: The dental X-rays (orthopantomogram, OPG) of 1053 outpatients (age: 14 to 24 years) were avaluated. The values "prosthetically restored", "filled dental root", or "periodontal bone loss" were recorded for each tooth present. The data were then evaluated using statistical tools. RESULTS: The correlation between the number of prosthetically restored teeth and the chronological age is high. The positive predictive value of determining an age of at least 18 years proved to be very high. However, these findings are rarely present in this age group. The number of endodontically treated teeth correlated less exactly with age. On the other hand, the determination of periodontal bone loss gave reasonable positive predictive values for the threshold value "chronological age of 18 years or more". DISCUSSION: This study provides for the first time predictive values for the estimation whether a person is 18 years of age, based on the evaluation of teeth with prosthetic restorations, root canal fillings or periodontal bone loss on OPGs only. Whereas the number of patients with such findings is generally low in this age group, some of the positive findings can be used for age estimation as an adjunct to other sources of age calculation. The sole application of these criteria is not recommended, as sanitary conditions of the teeth depend on both social and individual circumstances. Therefore, the calculated values also reflect the culture of the sample studied. Finally, they are time-dependent and have to be compared to data from other populations. These results have some bearing on the field of forensic odontology. 相似文献