首页 | 本学科首页   官方微博 | 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   44516篇
  免费   1603篇
  国内免费   5篇
各国政治   2152篇
工人农民   1813篇
世界政治   3285篇
外交国际关系   1696篇
法律   27327篇
中国共产党   42篇
中国政治   459篇
政治理论   8938篇
综合类   412篇
  2021年   273篇
  2020年   647篇
  2019年   755篇
  2018年   973篇
  2017年   1181篇
  2016年   1197篇
  2015年   871篇
  2014年   1009篇
  2013年   4422篇
  2012年   1156篇
  2011年   1288篇
  2010年   996篇
  2009年   1119篇
  2008年   1252篇
  2007年   1315篇
  2006年   1302篇
  2005年   1172篇
  2004年   1157篇
  2003年   1116篇
  2002年   1040篇
  2001年   1621篇
  2000年   1404篇
  1999年   1153篇
  1998年   678篇
  1997年   543篇
  1996年   533篇
  1995年   487篇
  1994年   561篇
  1993年   549篇
  1992年   792篇
  1991年   885篇
  1990年   851篇
  1989年   780篇
  1988年   849篇
  1987年   790篇
  1986年   887篇
  1985年   835篇
  1984年   696篇
  1983年   668篇
  1982年   468篇
  1981年   527篇
  1980年   383篇
  1979年   521篇
  1978年   388篇
  1977年   335篇
  1976年   282篇
  1975年   324篇
  1974年   361篇
  1973年   332篇
  1972年   271篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
This study developed a composite machine learning algorithm for attribution of materials of forensic interest (like ammonium nitrate) to original sources. k-nearest neighbor and random forest models were used for source elimination and classification, respectively, in a two-step, composite algorithm based on particle color, size/shape, and trace element concentration features. Novel approaches for simulation to supplement within-source reference features based on empirically measured multi-lot analyses, an improved hold-one-lot-out method for cross-validation, an assessment of the likelihood of the presence of a reference sample, fusion of the source probabilities from the respective classification models, and the calculation of metrics for assessing ensemble sourcing performance are described. Excellent sourcing predictions were obtained; the sourcing algorithm identified the correct source as the top choice 89% of the time, and the correct source was identified to be an average of 2.7 times more likely than the most likely incorrect source.  相似文献   
42.
43.
Lophophora is a member of the Cactaceae family, which contains two species: Lophophora williamsii and L. diffusa. Lophophora williamsii is an illegal plant containing mescaline, a hallucinogenic alkaloid. In this study, a novel method based on a single nucleotide polymorphism (SNP) assay was developed for identifying L. williamsii; this assay reliably detects SNPs within chloroplast DNA (rbcL, matK, and trnL-trnF IGS) and was validated for identifying Lophophora and L. williamsii simultaneously. The chloroplast DNA sequences from four L. williamsii and three L. diffusa plants were obtained and compared using DNA sequence data from approximately 300 other Cactaceae species available in GenBank. From this sequence data, a total of seven SNPs were determined to be suitable for identifying L. williamsii. A multiplex assay was constructed using the ABI PRISM® SNaPshot™ Multiplex Kit (Applied Biosystems, Forster City, CA) to analyze species-specific SNPs. Using this multiplex assay, we clearly distinguished the Lophophora among 19 species in the Cactaceae family. Additionally, L. williamsii was distinguished from L. diffusa. These results suggest that the newly developed assay may help resolve crimes related to illegal distribution and use. This multiplex assay will be useful for the genetic identification of L. williamsii and can complement conventional methods of detecting mescaline.  相似文献   
44.
45.
46.
This article analyses how a gendered perspective on community-based tourism (CBT) contributes to the realisation of identity and sovereignty of quilombos. It examines the potential sustainability of CBT coupled with agro-ecological practices within the context of gendered identity politics. Drawing from in-depth ethnographic and archival research conducted between February and July 2015 at Campinho da Independência (Rio de Janeiro, Brazil), the article discusses how female leaders integrate sustainable agro-ecological practices and CBT with environmental education in what they call ‘ethno-ecological tourism’. This approach to CBT strengthens a proudly defiant version of Afro-Brazilian ethnic identity vis-à-vis the state.  相似文献   
47.
The scope of directors’ duties forms perhaps the most important part of corporate governance. This paper considers the trajectory of the regulation of directors’ duties under Ghanaian company law from the Companies Act, 1963 (Act 179) to the Companies Act, 2019 (Act 992). Using the 2017 to 2019 financial institutions’ insolvencies in Ghana as a backdrop, it considers whether the scope, formulation and structure of directors’ duties within the new legislation is capable of promoting corporately-beneficial director behaviour. It also discusses whether the framework is apt to deal with similar lapses in corporate governance marked by reckless and opportunistic director behaviour. It discovers that Act 992 places a greater reliance on specific rules while retaining the largely principles-based regulatory technique adopted for regulating director conduct under Act 179. The overall tenor of the framework of directors’ duties under the new Act points to a firmer legislative view of the serious consequences of reckless director conduct. The paper concludes that the language of the framework regulating director conduct is capable of promoting corporately beneficially director behaviour and is also apt to deal with the kind of lapses in corporate governance which led to mass financial sector insolvencies in Ghana.  相似文献   
48.
This paper draws on recent research examining feminist and everyday geopolitics to focus on the relatively neglected domestic sphere as a space where geopolitical events like the Falklands/Malvinas war are learnt, (re)produced, remembered and contested by young people. It presents qualitative data drawn from interviews with young people from Argentina (Río Gallegos) and the Falkland Islands (Stanley), locations with intimate connections to the 1982 war. It argues that research in domestic environments that engages the familial relations, objects and practices that embody geopolitical pasts can help make sense of how young people (are able to) express geopolitical agency.  相似文献   
49.
In the case of suspicious deaths, the technique of 1:1 taping is often used in Belgium. It consists of affixing a large number of adhesive tapes to the body of the victim. It is conventionally aimed at obtaining microtraces (e.g., fibers, hair) and is usually not used for DNA analysis. However, in some cases, DNA analysis of certain areas of interest identified on the 1:1 taping material can offer a last resort solution. The four-step method that is described in this article involves the selection of areas of interest on the body (Step 1), the selection of the corresponding tapes (Step 2), the decontamination of the tapes (Step 3), the selection of areas of interest on the tapes, for DNA sampling (Step 4). The method is illustrated by its successful application in four murder cases. In each case, DNA profiles of good quality could be identified, including profiles of persons different from the victim.  相似文献   
50.
Abstract

Although the Syrian conflict continues, local and global stakeholders have already begun to consider the return of the six million refugees, especially as neither the option of local integration in the countries of first asylum nor that of resettlement to third countries is seen as a realistic possibility. Elaborating on the return debates in Turkey, Lebanon and Jordan, we relate the politicisation of this question to the growing acceptance of the option of voluntary and involuntary repatriation in the international refugee regime as well as to policies and public opinion. We argue, based on empirical fieldwork, that any debate about the return of Syrian refugees is problematic, since the conditions of safety, voluntariness and sustainability are not fulfilled. Further, returns should not be left entirely to the individual hosting states and actors in the region but should be carried out in collaboration with representative authorities in Syria and the mediation of international organisations upon full resolution of conflict.  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