全文获取类型
收费全文 | 469篇 |
免费 | 111篇 |
专业分类
各国政治 | 15篇 |
工人农民 | 1篇 |
世界政治 | 2篇 |
外交国际关系 | 37篇 |
法律 | 380篇 |
中国政治 | 16篇 |
政治理论 | 21篇 |
综合类 | 108篇 |
出版年
2024年 | 1篇 |
2023年 | 12篇 |
2022年 | 5篇 |
2021年 | 7篇 |
2020年 | 18篇 |
2019年 | 20篇 |
2018年 | 13篇 |
2017年 | 19篇 |
2016年 | 22篇 |
2015年 | 30篇 |
2014年 | 34篇 |
2013年 | 45篇 |
2012年 | 45篇 |
2011年 | 44篇 |
2010年 | 25篇 |
2009年 | 24篇 |
2008年 | 33篇 |
2007年 | 34篇 |
2006年 | 24篇 |
2005年 | 20篇 |
2004年 | 15篇 |
2003年 | 16篇 |
2002年 | 14篇 |
2001年 | 11篇 |
2000年 | 6篇 |
1999年 | 7篇 |
1998年 | 1篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 3篇 |
排序方式: 共有580条查询结果,搜索用时 937 毫秒
71.
72.
介绍国际海事组织制定国际海运温室气体减排法律制度的背景,分析制定相关法律制度的可行性和形势,提出并探讨四个关键问题,即立法目的、共同但有区别责任原则的体现、法律文件的形式、是否构成海运服务贸易壁垒,揭示其背后深层次的政治、经济、技术和法律问题,指出国际海运温室气体减排法律制度将给船舶技术、国际海运贸易、航运经营与运营带来深远影响。 相似文献
73.
74.
中国商业银行碳金融业务发展战略研究 总被引:1,自引:0,他引:1
当前碳金融已经成为全球商业银行竞争的新领域,中国商业银行拓展碳金融业务已是大势所趋。该文对中国发展碳金融的必要性和国内外商业银行在碳金融领域的发展现状进行了分析,指出了中国商业银行发展碳金融业务存在的七个主要障碍,进而提出了促进中国商业银行碳金融业务发展的对策建议。 相似文献
75.
Alternative fuels are becoming more prominent on the market today and, soon, fire debris analysts will start seeing them in liquid samples or in fire debris samples. Biodiesel fuel is one of the most common alternative fuels and is now readily available in many parts of the United States and around the world. This article introduces biodiesel to fire debris analysts. Biodiesel fuel is manufactured from vegetable oils and/or animal oils/fats. It is composed of fatty acid methyl esters (FAMEs) and is sold pure or as a blend with diesel fuel. When present in fire debris samples, it is recommended to extract the debris using passive headspace concentration on activated charcoal, possibly followed by a solvent extraction. The gas chromatographic analysis of the extract is first carried out with the same program as for regular ignitable liquid residues, and second with a program adapted to the analysis of FAMEs. 相似文献
76.
The analysis of motor oils has wide applications in the forensic science field from comparing lubricants transferred between an automobile and a victim or crime scene to differentiating the compositions of plastic explosives. In this study, 40 unused motor oils were analyzed and compared by high-temperature gas chromatography-mass spectrometry to determine the potential for oil individualization. Oil samples were also collected from the crankcase dipsticks of 30 cars. Twenty-six of these oils could be differentiated from each other based on visual comparisons of the unresolved envelope (baseline rise due to incomplete separation) and the resolved hydrocarbons in the raw total ion chromatograms (TICs) and smoothed TIC data. Four of these oils were analyzed as unknowns and were correctly related to the corresponding vehicle. The use of extracted ion profiles (EIPs) was explored as a means to further discriminate between the indistinct samples based on the polycyclic aromatic hydrocarbon (PAH) content. The research discussed in this paper demonstrated that differentiation of motor oils was possible by examining the TIC, smoothed TIC, and EIP data. 相似文献
77.
Traditional forensic soil comparisons are performed via physical and/or chemical examinations of color, texture, and mineral content, leaving any organic- or water-soluble fractions unexamined. This study uses high-performance liquid chromatography (HPLC) and ion chromatography (IC) to assess the qualitative and quantitative variation in these fractions of soil. Soil samples (n=120) were collected over the course of 3 weeks from urban, suburban, and rural locations in and around Lansing, MI. Additional samples from six of these locations (two urban, two suburban, and two rural) were collected once a week for 10 weeks for temporal analysis. Nine additional samples, equally spaced over a 1 m(2) grid, from these same six locations were collected for spatial analyses. Qualitative and quantitative analysis of the resultant chromatograms separated the 120 samples into 10 groups by HPLC and 23 groups by IC. This study shows that using HPLC and IC to analyze the organic- and water-soluble fractions of soil can successfully discriminate samples. Quantitative analysis of the results eliminates some false inclusions by providing further differentiation of samples. The results of this study indicate that adding HPLC and IC analyses to traditional forensic soil analysis schemes can improve overall sample differentiation. The methods used in this study were also able to detect both qualitative and quantitative variations in soil over a relatively small geographic area. This demonstration of soil heterogeneity underscores the importance of the collection of a representative known sample population when assessing a forensic soil comparison. Significant temporal variation was also demonstrated over the course of 10 weeks of sampling; however, samples were found to be consistent over shorter periods of time. Baseline levels of inorganic anions were determined via IC; these levels may be useful in assessing the significance of anions detected in soil from cases involving low explosives. 相似文献
78.
Allison M. Curran Ph.D. ; Paola A. Prada B.S. ; Kenneth G. Furton Ph.D. 《Journal of forensic sciences》2010,55(1):50-57
Abstract: Human scent evidence is utilized as an investigative tool through canine scent discriminations based on the premise that human scent is an individualizing characteristic. This study describes the development of what is effectively a human scent barcode consisting of the relative ratios of an individual's "primary odor" compounds utilized to determine a reproducible and individualizing profile which can be stored in a searchable database for a proof of concept of human scent as a biometric measure. Triplicate hand odor samples were evaluated from 10 subjects utilizing solid phase micro-extraction gas chromatography/mass spectrometry (SPME-GC/MS) and compared via Spearman Rank Correlations. Narrowing the compounds considered for each subject to only those common in all three samples, or a subject's "primary odor constituents," produced a greater degree of both individualization and discrimination; at both correlation thresholds of 0.9 and 0.8, the individuals were correctly discriminated and identified in 99.54% of the cases. 相似文献
79.
Anders Buchard M.Sc. Kristian Linnet M.D. D.M.Sc. Sys Stybe Johansen Ph.D. Julie Munkholm M.D. Michael Fregerslev M.D. Niels Morling M.D. D.M.Sc. 《Journal of forensic sciences》2010,55(2):457-463
Abstract: We investigated toxicological and pharmacogenetic factors that could influence methadone toxicity using postmortem samples. R‐ and S‐methadone were measured in femoral blood from 90 postmortem cases, mainly drug users. The R‐enantiomer concentrations significantly exceeded that of the S‐enantiomers (Wilcoxon’s test, p < 0.001). The samples were divided into four groups according to other drugs detected (methadone only, methadone and strong analgesics, methadone and benzodiazepines, or methadone and other drugs). There was no significant difference in any of the R‐methadone/total methadone ratios among the four groups. The median R/S ratio was 1.38, which tends to be higher than that reported for the plasma of living subjects. In addition, we investigated whether small nucleotide polymorphisms in the MDR1 gene that encode the drug transporter P‐glycoprotein were associated with the concentrations of R‐ and S‐methadone and its metabolite 2‐ethylidene‐1,5‐dimethyl‐3,3‐diphenylpyrrolidine. No significant association was detected. 相似文献
80.
Chang Liu B.Sc. Hyun M. Park Ph.D. Maria V. Monsalve Ph.D. David D. Y. Chen Ph.D. 《Journal of forensic sciences》2010,55(4):1039-1043
Abstract: Adipocere is a postmortem decomposition product consisting of mostly a mixture of free fatty acids (FFAs) that are formed because of the hydrolysis of triglycerides in adipose tissues. This article describes a simple and robust method for the extraction, identification, and quantification of FFA commonly found in adipocere using gas chromatography–mass spectrometry (GC/MS). This method was applied to analyze tissues from Kwäday Dän Ts’ìnchí, ancient remains discovered in a retreating glacier in the Tatshenshini‐Alsek Park, British Columbia, Canada in August 1999. The lyophilized tissues were grinded and extracted with hexane. The trimethylsilyl fatty acid derivatives were analyzed by GC/MS, and the relative abundances of myristic acid, palmitic acid, oleic acid, and stearic acid were determined. Milligram per gram levels of saturated fatty acids were found in the tissues of the ancient remains, while the levels of unsaturated fatty acids, such as palmitoleic acid, were found to be negligible. The results provided further evidence of the existence of adipocere found during forensic examination of the Kwäday Dän Ts’ìnchí ancient remains. 相似文献