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   216篇
  免费   15篇
各国政治   26篇
工人农民   15篇
世界政治   27篇
外交国际关系   11篇
法律   118篇
中国政治   1篇
政治理论   33篇
  2023年   6篇
  2022年   4篇
  2021年   7篇
  2020年   12篇
  2019年   16篇
  2018年   13篇
  2017年   16篇
  2016年   11篇
  2015年   4篇
  2014年   12篇
  2013年   30篇
  2012年   6篇
  2011年   5篇
  2010年   5篇
  2009年   5篇
  2008年   5篇
  2007年   13篇
  2006年   10篇
  2005年   17篇
  2004年   7篇
  2003年   8篇
  2002年   11篇
  2001年   1篇
  1999年   1篇
  1998年   1篇
  1996年   1篇
  1992年   1篇
  1991年   1篇
  1984年   1篇
  1983年   1篇
排序方式: 共有231条查询结果,搜索用时 78 毫秒
1.
The optical and morphological properties of resveratrol were investigated. This nontoxic fluorescent natural material, emitting in the visible blue light, was used as an optical marker, enabling the enhancement of the image contrast coming from relief pictures marked on challenging surfaces. By applying appropriated imaging softwares, this marker was verified to be very useful in the latent fingerprint recognition deposited on different wood surface types, mainly those with high level of roughness, where conventional forensic materials do not allow effective fingerprint image visualization.  相似文献   
2.
In December 2001, Argentina experienced a decisive crisis. A financial collapse accelerated by the massive flight of capital and the IMF denial of a new loan was followed by a popular insurrection which, by putting forward the slogan ¡ que se vayan todos, que no quede ni uno solo ! forced the resignation of national authorities. Whilst Duhalde's provisional government is negotiating the conditions for international financial support, faced with inflation and the rise of the dollar exchange rate, social mobilisation is expanding in new forms. This paper argues that the popular insurrection of December 2001 opened a space for the reinvention of the political as negative politics, the asambleas barriales constituting one example of this.  相似文献   
3.
This paper describes the analytical methodology for the determination of MDMA, MDA, MDEA and MBDB in oral fluid. After a liquid–liquid extraction, the analysis was carried out by high performance liquid chromatography (HPLC), with fluorescence detection. The detector wavelength was fixed at 285 nm for excitation and 320 nm for emission. The mobile phase, a mixture of phosphate buffer (pH = 5) and acetonitrile (75:25), and the column, Kromasil 100 C8 5 μm 250 mm × 4.6 mm, allowed good separation of the compounds in an isocratic mode in only 10 min. The method was validated and showed good limits of detection (2 ng/mL) and quantitation (10 ng/mL) for all the amphetamine derivatives. No interfering substances were detected. A stability study of these compounds in oral fluid stored at three different temperatures (−18, 4 and 20 °C) over 10 weeks was conducted, showing a time-dependent degradation of the four compounds.  相似文献   
4.
We discuss how far accountability practices may be relevant to the success of independent regulators in countries without a tradition of administrative autonomy. We develop a conceptualisation of agency accountability failures and develop an analytical framework to examine the life and termination of the Spanish regulatory agency for telecommunications, CMT (Comisión del Mercado de las Telecomunicaciones - Telecommunications Market Commission). We argue that the CMT’s termination was related, among other reasons, to accountability failures in its institutional design. The paper relies on a variety of sources, including legislation, literature, media coverage, and semistructured interviews with agency officials and several stakeholders.  相似文献   
5.
6.
Appraisals about the implications of stressful events that are evaluated as involving a threat to self (negative self-evaluation, negative evaluation from others, rejection by others) have been shown to place youth at risk for the development of mental health problems. This longitudinal study tested a protective-stabilizing interactive model, in which high maternal acceptance was predicted to mitigate the prospective relation between threat to self appraisals and change in adolescents’ mental health problems six months later. Participants were 89 adolescents from divorced families ages 10–12 and residential mothers. Adolescents reported on threat to self appraisals from the most stressful event experienced in the past month. Mothers and youth reported on maternal acceptance and mental health problems. Multiple regression analyses provided support for the protective effects of maternal acceptance on adolescents’ mental health problems. Intervention implications are discussed. Ana Brown is a pre-doctoral fellow in prevention research (NIMH 2 T32 MH18387–19) and doctoral student in the Department of Psychology at Arizona State University, Tempe, AZ. Research interests include the study of children’s appraisals and responses to stressful events in the prevention of mental health problems. Sharlene Wolchik is a clinical psychologist and professor in the Department of Psychology at Arizona State University, Tempe, AZ. Her research focuses on identifying risk and protective factors for children whose parents have divorced. She also has designed and evaluated the efficacy of preventive interventions for children from divorced families and children who have experienced parental bereavement. Jenn-Yun Tein is a research associate professor and Co-Director of the Research Methodology Core of the Prevention Research Center at Arizona State University, Tempe, AZ. Her research interests include analyses of mediation and moderation of preventive interventions as well as applications of methodology and statistics in prevention research. Irwin Sandler is a Regents’ Professor in the Department of Psychology and Director of the Prevention Research Center at Arizona State University, Tempe, AZ. His research interests focus on understanding resilience for children exposed to stress and on the development, evaluation and dissemination of programs to promote resilience and prevent mental health problems for children in stress.  相似文献   
7.
Gene and genotype frequencies in relation to the D3S1358, vWA, FGA, TH01, TPOX, CSF1PO, D5S818, D13S317, and D7S820 loci were determined in a sample of 290 unrelated individuals (204 Caucasians and 86 mulattoes) living in the city of S?o Paulo, Brazil. The sex test Amelogenin was also performed in all subjects from our sample, revealing the expected sex in all instances. Allele frequency data obtained from the analysis of these samples were in the usual range of other population groups with similar racial background. In the sample of Caucasian individuals, panmictic proportions were ruled out in relation to TPOX and CSF1PO loci, but only in the latter was the overall frequency of heterozygotes significantly less than expected. In the sample of mulattoes, Hardy-Weinberg proportions were rejected in relation to FGA and CSF1PO loci, but in no instance were the overall numbers of heterozygotes different from the corresponding expected ones under panmixia. Taking into account all this and also the number of tests performed, the degree of genetic heterogeneity of Brazilian populations, and the critical level reached by the significant results (1% < alpha<5%), the departures from panmixia here observed can be considered to be negligible in altering significantly biologic relationship odds calculated under the assumption of random matings.  相似文献   
8.
A sensitive analytical method was developed for quantitative analysis of delta(9)-tetrahydrocannabinol (delta(9)-THC), 11-nor-delta(9)-tetrahydrocannabinol-carboxylic acid (delta(9)-THC-COOH), cannabinol (CBN) and cannabidiol (CBD) in human hair. The identification of delta(9)-THC-COOH in hair would document Cannabis use more effectively than the detection of parent drug (delta(9)-THC) which might have come from environmental exposure. Ketamine was added to hair samples as internal standard for CBN and CBD. Ketoprofen was added to hair samples as internal standard for the other compounds. Samples were hydrolyzed with beta-glucuronidase/arylsulfatase for 2h at 40 degrees C. After cooling, samples were extracted with a liquid-liquid extraction procedure (with chloroform/isopropyl alcohol, after alkalinization, and n-hexane/ethyl acetate, after acidification), which was developed in our laboratory. The extracts were analysed before and after derivatization with pentafluoropropionic anhydride (PFPA) and pentafluoropropanol (PFPOH) using a Hewlett Packard gas chromatographer/mass spectrometer detector, in electron impact mode (GC/MS-EI). Derivatized delta(9)-THC-COOH was also analysed using a Hewlett Packard gas chromatographer/mass spectrometer detector, in negative ion chemical ionization mode (GC/MS-NCI) using methane as the reagent gas. Responses were linear ranging from 0.10 to 5.00 ng/mg hair for delta(9)-THC and CBN, 0.10-10.00 ng/mg hair for CBD, 0.01-5.00 ng/mg for delta(9)-THC-COOH (r(2)>0.99). The intra-assay precisions ranged from <0.01 to 12.40%. Extraction recoveries ranged from 80.9 to 104.0% for delta(9)-THC, 85.9-100.0% for delta(9)-THC-COOH, 76.7-95.8% for CBN and 71.0-94.0% for CBD. The analytical method was applied to 87 human hair samples, obtained from individuals who testified in court of having committed drug related crimes. Quantification of delta(9)-THC-COOH using GC/MS-NCI was found to be more convenient than GC/MS-EI. The latter may give rise to false negatives due to the detection limit.  相似文献   
9.
10.
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