全文获取类型
收费全文 | 3450篇 |
免费 | 89篇 |
专业分类
各国政治 | 328篇 |
工人农民 | 73篇 |
世界政治 | 367篇 |
外交国际关系 | 257篇 |
法律 | 1275篇 |
中国共产党 | 1篇 |
中国政治 | 23篇 |
政治理论 | 1176篇 |
综合类 | 39篇 |
出版年
2023年 | 10篇 |
2022年 | 14篇 |
2021年 | 33篇 |
2020年 | 62篇 |
2019年 | 60篇 |
2018年 | 99篇 |
2017年 | 118篇 |
2016年 | 120篇 |
2015年 | 77篇 |
2014年 | 94篇 |
2013年 | 600篇 |
2012年 | 90篇 |
2011年 | 102篇 |
2010年 | 86篇 |
2009年 | 124篇 |
2008年 | 153篇 |
2007年 | 141篇 |
2006年 | 101篇 |
2005年 | 110篇 |
2004年 | 107篇 |
2003年 | 88篇 |
2002年 | 95篇 |
2001年 | 71篇 |
2000年 | 64篇 |
1999年 | 68篇 |
1998年 | 61篇 |
1997年 | 55篇 |
1996年 | 46篇 |
1995年 | 57篇 |
1994年 | 47篇 |
1993年 | 45篇 |
1992年 | 29篇 |
1991年 | 49篇 |
1990年 | 26篇 |
1989年 | 41篇 |
1988年 | 32篇 |
1987年 | 36篇 |
1986年 | 50篇 |
1985年 | 15篇 |
1984年 | 25篇 |
1983年 | 30篇 |
1982年 | 31篇 |
1981年 | 19篇 |
1980年 | 27篇 |
1979年 | 17篇 |
1978年 | 22篇 |
1977年 | 16篇 |
1976年 | 16篇 |
1974年 | 20篇 |
1973年 | 8篇 |
排序方式: 共有3539条查询结果,搜索用时 0 毫秒
881.
Criticisms of the forensic discipline of bitemark analysis state that the range of distortion in the shape of bitemark impressions in skin has not been scientifically established. No systematic statistical studies exist that explore this problem. As a preliminary investigation of this issue, a single dentition was mounted in a mechanical apparatus and used to create 89 bitemarks in human cadaver skin, both parallel and perpendicular to tension lines. Impressions of the same dentition were also created in wax. 2D scanned images of the biting dentition were obtained. Locations of incisal edges of all 6 anterior teeth as well as the midpoint of the canine were captured as landmarks in all specimens. This set of landmark data was then studied using established geometric morphometric methods. All specimen shapes were compared using Procrustes superimposition methods, and by a variation of Procrustes superimposition which preserves scale information. Match criteria were established by examining the range of variation produced by repeated measurements of the dentition for each class of specimen. The bitemarks were also compared to a population of 411 digitally scanned dentitions, again using the match criteria. Results showed that bitemarks in wax had lower measurement error than scanned images of the dentition, and both were substantially lower than measurement error as recorded in skin. None of the 89 bitemarks matched the measured shape of the biting dentition or bitemarks in wax, within the repeated measurements error level, despite the fact that all bitemarks were produced by this dentition. Comparison of the bitemarks to the collection of 411 dentitions showed that the closest match to the bitemarks was not always the same dentition that produced the bitemarks. Examination of Procrustes plots of matched shapes showed non-overlapping distributions of measurements of bitemarks in skin, wax, and the dentition. All had statistically significant differences in mean shape. Principal component analysis (PCA) and canonical variates analysis (CVA) both showed clear segregation of the three types of data. The patterns of variance revealed by PCA showed several distinct patterns produced by skin distortion; alteration of relative arch width, and varying displacement of non-aligned teeth in the dentition. These initial results indicate that when multiple suspects possess similar dentitions, bitemark analysis should be approached with caution. 相似文献
882.
This article analyzes the impact of The Community Resources Group Receivership Program undertaken from 1998 to 2002 that provided clean property titles to residents in several informal housing colonias (subdivisions) in South Texas. Survey data were gathered from 260 low‐income households comprising two populations: those who had secure title from the outset, and those who were beneficiaries of the land titling program. Focus group interviews were conducted to explore how the beneficiaries construct the meaning of ownership before and after title “regularization.” Formal titling consolidates understandings of absolute property relations in comparison with de facto rights born of use (legal or not), which strengthens people's sense of self‐esteem and potential for political involvement. We found that, contrary to conventional wisdom, title provision per se appears to have little direct impact either upon home improvement or upon residents' receiving enhanced access to credit and financial services. We also found evidence that informality and illegality is likely to reemerge as owners die intestate, and as they revert to informal land market property transfers. 相似文献
883.
884.
Peter Knoepfel 《Swiss Political Science Review》2011,17(2):188-219
Abstract: The implementation of climate change adaptation polices has barely occurred in developed countries. This paper examines to what extent the perceptions of political actors might hinder the development of adaptation policies. We study the Swiss case using computer aided textual analysis. Our results demonstrate that adaptation is still not perceived as an important dimension of climate change policy. Decision makers do not perceive links between adaptation, the Swiss economy and the energy supply. Adaptation is mainly considered an issue for developing countries and not as a way to reduce the impacts of climate change in Switzerland. Right‐wing parties tend to consider adaptation a secondary issue and are more likely than those to the left to object to the formulation or the implementation of public measures. 相似文献
885.
Agroecology has played a key role in helping Cuba survive the crisis caused by the collapse of the socialist bloc in Europe and the tightening of the US trade embargo. Cuban peasants have been able to boost food production without scarce and expensive imported agricultural chemicals by first substituting more ecological inputs for the no longer available imports, and then by making a transition to more agroecologically integrated and diverse farming systems. This was possible not so much because appropriate alternatives were made available, but rather because of the Campesino-a-Campesino (CAC) social process methodology that the National Association of Small Farmers (ANAP) used to build a grassroots agroecology movement. This paper was produced in a 'self-study' process spearheaded by ANAP and La Via Campesina, the international agrarian movement of which ANAP is a member. In it we document and analyze the history of the Campesino-to-Campesino Agroecology Movement (MACAC), and the significantly increased contribution of peasants to national food production in Cuba that was brought about, at least in part, due to this movement. Our key findings are (i) the spread of agroecology was rapid and successful largely due to the social process methodology and social movement dynamics, (ii) farming practices evolved over time and contributed to significantly increased relative and absolute production by the peasant sector, and (iii) those practices resulted in additional benefits including resilience to climate change. 相似文献
886.
Adler PW 《Journal of law and medicine》2011,19(2):335-353
Since 1965, tens of millions of boys have been circumcised under the Medicaid program, most at birth, at a cost to the United States Federal Government, the States and taxpayers of billions of dollars. Although 18 States have ended coverage since 1982, the United States Government and 32 States continue to pay for non-therapeutic circumcision, even though no medical association in the world recommends it. Many cite American medical association policy that the procedure has potential medical benefits as well as disadvantages, and that the circumcision decision should be left to parents. This article shows that Medicaid coverage of circumcision is not a policy issue because it is prohibited by federal and State law. As American medical associations concede, non-therapeutic circumcision is unnecessary, elective, cosmetic surgery on healthy boys, usually performed for cultural, personal or religious reasons. The fundamental principle of Medicaid law is that Medicaid only covers necessary medical treatments after the diagnosis of a current medical condition. Physicians and hospitals face severe penalties for charging Medicaid for circumcisions. Medicaid officials and the Federal and State Governments are also required to end coverage. It is unlawful to circumcise and to allow the circumcision of healthy boys at the expense of the government and taxpayers. 相似文献
887.
888.
This article examines the impact of ethnic diversity in Danish municipalities on citizens' social trust over the last three decades. During this period, Danish society has grown increasingly ethnically diverse, and this begs the question whether this has influenced trust in others negatively. Existing evidence from the Anglo‐Saxon countries would suggest that this is the case, whereas evidence from the European continent mainly suggests that no link exists between ethnic diversity and social trust. The empirical analysis uses individual‐level data on social trust from several surveys in Denmark in the period from 1979 to 2009 coupled with diversity at the municipality level. Individual‐level measures of trust over time enable estimation of the impact of changes in ethnic diversity within municipalities on social trust and, it is argued, thereby a more precise estimate of the effect of ethnic diversity on trust. The results suggest that social trust is negatively affected by ethnic diversity. The article concludes by discussing this result and suggest avenues for further research. 相似文献
889.
Smith K Alford JR Hatemi PK Eaves LJ Funk C Hibbing JR 《American journal of political science》2012,56(1):17-33
Evidence that political attitudes and behavior are in part biologically and even genetically instantiated is much discussed in political science of late. Yet the classic twin design, a primary source of evidence on this matter, has been criticized for being biased toward finding genetic influence. In this article, we employ a new data source to test empirically the alternative, exclusively environmental, explanations for ideological similarities between twins. We find little support for these explanations and argue that even if we treat them as wholly correct, they provide reasons for political science to pay more rather than less attention to the biological basis of attitudes and behaviors. Our analysis suggests that the mainstream socialization paradigm for explaining attitudes and behaviors is not necessarily incorrect but is substantively incomplete. 相似文献
890.
Romão W Vaz BG Lalli PM Bueno MI Correa DN Telles VL de Castro EV Eberlin MN 《Journal of forensic sciences》2012,57(2):539-543
Using desorption/ionization techniques such as easy ambient sonic-spray ionization mass spectrometry (EASI-MS), it is possible to analyze documents of Brazilian vehicles for authenticity, providing a chemical profile directly from the surface of each document. A method for the detection of counterfeit documents is described, and the falsification procedure is elucidated. Forty authentic and counterfeit documents were analyzed by both positive and negative ion modes, EASI(±)-MS. EASI(+)-MS results identified the presence of (bis(2-ethylhexyl)phthalate plasticizer and of dihexadecyldimethylammonium biocide in both types of documents. For EASI(-)-MS results, the 4-octyloxybenzoic acid additive ([M + H](+): m/z 249) is present only in counterfeit documents. It was also found that counterfeit vehicle documents are produced via Laserjet printers. Desorption/ionization techniques, such as EASI-MS, offer therefore, an intelligent way to characterize the counterfeiting method. 相似文献