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   1385篇
  免费   66篇
各国政治   90篇
工人农民   90篇
世界政治   105篇
外交国际关系   78篇
法律   684篇
中国共产党   1篇
中国政治   46篇
政治理论   354篇
综合类   3篇
  2023年   13篇
  2022年   10篇
  2021年   16篇
  2020年   39篇
  2019年   44篇
  2018年   63篇
  2017年   54篇
  2016年   62篇
  2015年   38篇
  2014年   45篇
  2013年   206篇
  2012年   46篇
  2011年   50篇
  2010年   44篇
  2009年   48篇
  2008年   52篇
  2007年   55篇
  2006年   38篇
  2005年   44篇
  2004年   33篇
  2003年   32篇
  2002年   30篇
  2001年   36篇
  2000年   29篇
  1999年   28篇
  1998年   12篇
  1997年   19篇
  1996年   12篇
  1995年   20篇
  1994年   16篇
  1993年   17篇
  1992年   21篇
  1991年   21篇
  1990年   13篇
  1989年   10篇
  1988年   9篇
  1987年   10篇
  1986年   12篇
  1985年   11篇
  1984年   8篇
  1983年   11篇
  1982年   6篇
  1981年   12篇
  1979年   5篇
  1978年   9篇
  1977年   4篇
  1974年   4篇
  1972年   6篇
  1968年   3篇
  1967年   5篇
排序方式: 共有1451条查询结果,搜索用时 15 毫秒
61.
62.
63.
64.
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   
65.
Journal of Youth and Adolescence - Young adults experience social role transitions across multiple life domains, and a deeper understanding of the ways in which these simultaneous transition...  相似文献   
66.
When using non-FTA cards in commercial multiplex STR kits for direct PCR, pretreatment steps with specific buffers are recommended. Here, we designed a rapid direct PCR method utilizing a non-FTA card, Oral Cell Sampling Kit, by omitting the pretreatment step involving Prep-n-Go™ Buffer, and it showed compatibility with the GlobalFiler™ Express PCR Amplification Kit, GlobalFiler™ PCR Amplification Kit, and PowerPlex® Fusion system. To optimize the PCR conditions, we tested the method with different final PCR volumes and cycles. Finally, we conducted a performance test using 50 Korean buccal samples and confirmed the high performance of the method, detecting more than 90% of the samples with full profiles when using GlobalFiler™ PCR Amplification Kit and PowerPlex® Fusion system at 29 cycles in a 10 μL final PCR volume. Thus, we report a simple direct PCR set-up to analyze reference samples collected using a non-FTA card manufactured in Korea.  相似文献   
67.
Network-attached storage (NAS) is a system that uses a redundant array of disks (RAID) to create virtual disks comprising multiple disks and provide network services such as FTP, SSH, and WebDAV. Using these services, the NAS's virtual disks store data about individuals or groups, making them a critical analysis target for digital forensics. Well-known storage manufacturers like Seagate, Synology, and NETGEAR use Linux-based software RAID, and they usually support Berkeley RAID (e.g., RAID 0, 1, 5, 6, and 10) as well as self-developed hybrid RAID. Those manufacturers have published data on the introduction and features of hybrid RAID, but there is not enough information to reassemble RAID from a digital forensic perspective. Besides, digital forensic tools (such as EnCase, FTK, X-ways, and RAID Reconstructor) do not support automatic RAID reassembly for hybrid RAID, so research on hybrid RAID reassembly methods is necessary. This paper analyzes the disk array composed of hybrid RAID and explains the layout of disk array, partition layout in hybrid RAID, and hybrid RAID configuration strategy. Furthermore, it suggests parameters that are required for RAID reassembly and then propose a hybrid RAID reassembly procedure using them. Finally, we propose a proof-of-concept tool (Hybrid RAID Reconstructor) that identifies hybrid RAID from disk array and parse RAID parameters.  相似文献   
68.
This study is the first to examine the background level of male DNA on underpants worn by females in the absence of sexual contact. Here, we examined 103 samples from the inside front of underpants from 85 female volunteers. Samples were examined for the presence of male DNA using NGM SElect and PowerPlex Y23 kits. Only five samples gave a “complete” Y-STR profile, even though 83.5% of our volunteers cohabited with a male. In all cases where a partner reference sample was available, the Y-STR profile matched the cohabiting partner. We have demonstrated that a Y-STR profile is not expected on the inside front of underpants worn by females after social contact alone. The results of this study are informative for evaluating the significance of a Y-STR profile on underpants in cases of alleged sexual assault.  相似文献   
69.

Young adulthood represents a developmental period with disproportionately heightened risk of losing a job. Young adult unemployment has been linked to increased mental health problems, at least in the short term. However, their possible long-term impacts, often referred as “scarring effects,” have been understudied, possibly underestimating the magnitude of mental health burden that young adult unemployment generates. This longitudinal study examined whether duration of unemployment during young adulthood is associated with later mental health disorders, after accounting for mental and behavioral health problems in childhood. Furthermore, the current study investigated whether childhood neighborhood characteristics affect this association and if so, in what specific functional ways. Data were drawn from a longitudinal study of developmental outcomes in a community sample in Seattle. Data collection began in 1985 when study participants were elementary students and involved yearly assessments in childhood and adolescence (ages 10–16) and then biennial or triennial assessments (ages 18–39; N?=?677 at age 39; 47% European American, 26% African American, 22% Asian American, and 5% Native American; 49% female). The current study findings suggest that duration of unemployment across young adulthood increased mental health problems at age 39, regardless of gender. Childhood neighborhood characteristics, particularly their positive aspect, exerted independent impacts on adult mental health problems beyond unemployment experiences across young adulthood. The current findings indicate a needed shift in service profiles for unemployed young adults—a comprehensive approach that not only facilitates reemployment but also addresses mental health needs to help them to cope with job loss. Further, the present study findings suggest that childhood neighborhoods, particularly positive features such as positive neighborhood involvement, may represent concrete and malleable prevention targets that can curb mental health problems early in life.

  相似文献   
70.
Latinas in the United States are at a disproportionate risk for STDs and sexual risk behaviors. Among Latinas, acculturation has been found to be one of the most important predictors of these behaviors. Therefore, this study examined the longitudinal association between Latina adolescents’ level of acculturation and multiple sexual risk outcomes, including self-report STD diagnosis, four or more life-time sex partners, regret of sexual initiation after alcohol use, and lack of condom use during young adulthood. Based on the National Longitudinal Study of Adolescent Health (Add Health), this study includes a nationally representative sample of 1,073 Latina adolescents (ages 11–20 at Wave 1) transitioning into young adulthood (ages 18–27 at Wave 3). Our findings indicate that more acculturated Latinas who spoke English at home were more likely to have STDs and to exhibit sexual risk behaviors than Latinas who were foreign-born and did not use English at home. Interventions that aim to promote sexual and reproductive health among young Latinas should take into consideration their different levels of acculturation. This approach holds greater potential for reducing health disparities among Latinas.  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