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   315篇
  免费   8篇
各国政治   28篇
工人农民   5篇
世界政治   2篇
法律   262篇
中国政治   12篇
政治理论   13篇
综合类   1篇
  2024年   38篇
  2023年   150篇
  2021年   36篇
  2020年   3篇
  2018年   1篇
  2017年   3篇
  2016年   2篇
  2015年   3篇
  2013年   23篇
  2012年   9篇
  2011年   8篇
  2010年   11篇
  2009年   10篇
  2008年   5篇
  2007年   1篇
  2006年   4篇
  2005年   1篇
  2004年   3篇
  2001年   1篇
  2000年   2篇
  1998年   1篇
  1997年   2篇
  1991年   3篇
  1989年   1篇
  1984年   1篇
  1983年   1篇
排序方式: 共有323条查询结果,搜索用时 15 毫秒
241.
The last few years have witnessed the change in the modalities of smuggling of synthetic cannabinoid receptor agonists (SCRAs) by impregnating them in mail envelopes and fast parcels. Considering the aforementioned scenario, it is important to develop a portable technique to identifying SCRAs through packages. The purpose of this research was to detect SCRAs impregnated into substrates of paper using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Three SCRAs that included 5F-PB-22, AB-FUBINACA and AKB-48 were purchased from Sigma Aldrich. The three SCRAs and four cutting agents were impregnated into paper of variable thickness at four concentrations (10, 15, 20, and 25 mg/mL). Spectra were collected over the wavenumber range of 650–4000 cm−1 using ATR-FTIR spectroscopy and were exported to Matlab 2020b where data analysis was applied. The FTIR spectral data was able to show the three SCRAs could be detected on paper using ATR-FTIR spectroscopy and quantitatively modeled using the partial least squares regression algorithm. Principal component analysis showed separate clustering for the compounds that crystallized (5F-PB-22, AB-FUBINACA and caffeine) onto the papers surface from those impregnated into the bulk of the paper (AKB-48 and procaine) with the latter situated near blank papers in score plots. In summary, ATR-FTIR spectroscopy has proven to be a successful non-destructive technique in detecting and quantifying a selection of SCRAs impregnated into paper.  相似文献   
242.
Touch DNA has become increasingly important evidence in todays' forensic casework. However, due to its invisible nature and typically minute amounts of DNA, the collection of biological material from touched objects remains a particular challenge that underscores the importance of the best collection methods for maximum recovery efficiency. So far, swabs moistened with water are often utilized in forensic crime scene investigations for touch DNA sampling, even though an aqueous solution provokes osmosis, endangering the cell's integrity. The aim of the research presented here was to systematically determine whether DNA recovery from touched glass items can be significantly increased by varying swabbing solutions and volumes compared with water-moistened swabs and dry swabbing. A second objective was to investigate the possible effects of storage of swab solutions prior to genetic analysis on DNA yield and profile quality when stored for 3 and 12 months, as is often the case with crime scene samples. Overall, the results indicate that adapting volumes of the sampling solutions had no significant effect on DNA yield, while the detergent-based solutions performed better than water and dry removal, with the SDS reagent yielding statistically significant results. Further, stored samples showed an increase in degradation indices for all solutions tested, but no deterioration in DNA content and profile quality, allowing for unrestricted processing of touch DNA samples stored for at least 12 months. One further finding was a strong intraindividual change in DNA amounts observed over the 23 deposition days which may be related to the donor's menstrual cycle.  相似文献   
243.
While efforts have been made to reduce the pervasive backlog of sexual assault evidence collection kits, the actual laboratory process remains very time-consuming due to the requirement of a differential lysis step before DNA purification, as well as intricate mixture analysis towards the end of the DNA workflow. Recently, an alternative, direct-to-amplification sperm lysis method (using 1 M NaOH) was identified. However, a direct cell lysis method for non-sperm cells has not been identified yet. Thus, the primary objective of this work was to find an alternative method that is quick, inexpensive, and does not require multiple purification steps for the lysis of non-sperm cells in sexual assault samples. In this study, vaginal swab samples were lysed with the control method, prepGEM™, as well as six alternative reagents: alkaline buffer with 25–200 mM NaOH, high-salt stain extraction buffer, modified radioimmunoprecipitation assay (RIPA) buffer, mammalian protein extraction reagent (M-PER™), digitonin buffer, and urea/thiourea buffer. Quantification using Quantifiler® Trio of vaginal and semen lysates revealed that the alkaline (25 mM NaOH) and M-PER™ methods were efficient for the lysis of vaginal epithelial cells without substantial sperm cell lysis. Following quantification, analysis of STR profiles from vaginal lysates revealed that the M-PER™ method showed promising results across all metrics examined, including the percentage of detected STR alleles, mean peak heights, peak height ratio, and interlocus balance. Thus, this method was recommended as an alternative to the traditional differential lysis method for non-sperm cells given its ability to produce amplification-ready lysates without any DNA purification step.  相似文献   
244.
Cocaine and methamphetamine remain highly abused drugs in the United States due to their euphoric effects. This study examines classical stimulant casework, defined as cases positive for methamphetamine and/or cocaine, received by the Toxicology Laboratory and the Drug Analysis Laboratory at the Dallas County Southwestern Institute of Forensic Sciences from local law enforcement agencies and/or the Office of the Medical Examiner (OME) between January 1, 2017, and December 31, 2022. Methamphetamine positivity increased from 10.4% to 20.3% in the Toxicology Laboratory over the 6 years, whereas cocaine positivity remained relatively stable at approximately 17%. Similarly, in the Drug Analysis Laboratory, the methamphetamine positivity rate changed from 24.8% to 33.2%, whereas cocaine identification remained stable at approximately 20%. Blood concentrations of methamphetamine in OME cases ranged from 10.1–42,740.0 ng/mL while they were lower in DWI casework ranging from 10.2–2385.0 ng/mL. The blood concentration trends of cocaine were similar to methamphetamine, with OME casework ranging higher (10.0–24,501.0 ng/mL) than DWI casework (10.2–371.6 ng/mL). Polydrug use was evident for both methamphetamine and cocaine in postmortem cases, and the top three most frequently co-occurring drug/drug class were opioids/opiates, cannabinoids, and ethanol. The results from this study aid in the understanding of historical usage trends of cocaine and methamphetamine in Dallas County and how those trends have changed over time as newer stimulant drugs have emerged.  相似文献   
245.
The benzylation of three low molecular weight N,N-disubstituted ethanolamines related to chemical warfare agents (CWAs) to furnish derivatives with improved gas chromatography-mass spectrometry (GC-MS) profiles is described. Due to their low molecular weight and polar nature, N,N-disubstituted ethanolamines are notoriously difficult to detect by routine GC-MS analyses during Organisation for the Prohibition of Chemical Weapons (OPCW) proficiency tests (PTs), particularly in scenarios when they are present at low levels (~1–10 ppm) amidst more abundant interferences. Our studies revealed that the optimal derivatization conditions involved the treatment of the ethanolamine with benzyl bromide in the presence of an inorganic base (e.g., Na2CO3) in dichloromethane at 55°C for 2 h. This optimized set of conditions was then successfully applied to the derivatization of N,N-dimethylethanolamine, N,N-diethylethanolamine and N,N-diisopropylethanolamine present separately at 1 and 10 μg/mL concentrations in a glycerol-rich matrix sample featured in the 48th OPCW PT. The benzylated derivatives of the three ethanolamines possessed retention times long enough to clear the massive glycerol-containing matrix interferences. The protocol herein is introduced as an alternative method for derivatization of these CWA and pharmaceutically important species and should find broad applicability in laboratories where routine forensic analysis is carried out.  相似文献   
246.
Expanding bullets are preferred by law enforcement because of their wounding potential and ability to avoid over-penetration which could result in unintended targets being struck by bullets that perforate their intended targets. Expansion failure for jacketed hollow point (JHP) bullets is commonly attributed to several causes including damage to the bullet's cavity, velocity loss, bullet destabilization and materials from intermediate targets filling the bullet's cavity which can cause expansion failure when the bullet subsequently impacts a soft, fluid-based target such as human tissue or ballistic gelatin. In this study, JHP bullets were fired into ballistic gelatin after passing through selected intermediate targets representing items common to shooting incidents. Velocity loss and bullet destabilization were not factors that contributed to the JHP bullets that experienced expansion failure; however, materials obstructing the bullets' cavities and damage to the bullets' cavities were considered causes for some of the JHP bullet expansion failures. It was determined through this research that most of the target materials caused JHP bullet expansion failure when shored against the ballistic gelatin, but when placed at distances of 7 ft. from the ballistic gelatin, bullets fired through the same target materials did expand. This original and unique study produced findings that are of significant value to shooting incident reconstruction experts and other forensic professionals as shooting incidents can call into question a victim's proximity to a wall or door when a bullet(s) perforated such a target material.  相似文献   
247.
This article discusses different features of heterosexual soft‐ and hardcore pornography from the perspective of heterosexual masculinity and (in)visibility. It examines the embodiment of sexuality through the female body in lads' softcore magazines and the position of the phallus and the male body in some hardcore magazines and films. The article takes its startingpoint from notions of the problematic relationship between the depiction of the male body and desire, arguing that different visual techniques are used in sexual settings in order to maintain the status of the male (primarily white) body and the penis as being particular and distinct from other bodies.  相似文献   
248.
This study analyzes the relationship between race/ethnicity and sentencing outcomes for female drug offenders in Florida. Grounded in the focal concerns perspective, the research examines whether, in the specific case of drug offenders, minority women are treated more harshly than White women. Interaction models are estimated to determine the influence of drug offense type on racial and ethnic sentencing disparities. Differences in sentencing outcomes are also examined following significant policy changes in the state. In general, the findings suggest that minority female drug offenders are disadvantaged at both the incarceration and sentence length decisions. It also appears that perceptions of dangerousness associated with female offenders' race/ethnicity and offense are incorporated into sentencing authorities' patterned responses. That is, the level of disparity between Black, Hispanic, and White females is conditioned by type of drug offense in the interaction models. The changes in sentencing policy also impact the role of race and ethnicity in sentencing decisions. By analyzing drug offenders exclusively, the current study clarifies the role of race in sentencing decisions for females. In contrast to prior research that examined all offense categories together, the current study suggests that for drug offenses, minority females may, in fact, be deemed more dangerous and culpable than White female drug offenders.  相似文献   
249.
原产地规则是FTA的重要组成部分。本文首先分析了东亚FTA体系中原产地规则的特征,然后从理论上研究了现有的原产地规则对东亚生产体系的不利影响,重点分析了影响机制和渠道。最后,结合东亚现状提出了一些建议。  相似文献   
250.
新近,国际法院在相关的司法判例中提出了公平原则及相关情况规则,尤其在2009年罗马尼亚诉乌克兰黑海划界案中确认了这一具体规则及其适用方法。该项规则是建立在公平基础之上的,相比其他划界方法而言,更强调原则的属性。实际上,公平原则常常使用各种方法的结合以便取得公平结果。由于公平原则在划界领域可以平衡各种公平因素,因此在海洋边界划分中具有习惯法的地位。据此原则,中国有关东海大陆架划界的基本主张不容置疑。  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