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   843篇
  免费   43篇
各国政治   60篇
工人农民   29篇
世界政治   70篇
外交国际关系   25篇
法律   510篇
中国政治   20篇
政治理论   158篇
综合类   14篇
  2024年   38篇
  2023年   151篇
  2022年   3篇
  2021年   39篇
  2020年   14篇
  2019年   10篇
  2018年   16篇
  2017年   36篇
  2016年   21篇
  2015年   20篇
  2014年   21篇
  2013年   104篇
  2012年   22篇
  2011年   34篇
  2010年   29篇
  2009年   19篇
  2008年   27篇
  2007年   14篇
  2006年   29篇
  2005年   14篇
  2004年   16篇
  2003年   19篇
  2002年   17篇
  2001年   7篇
  2000年   12篇
  1999年   12篇
  1998年   14篇
  1997年   10篇
  1996年   9篇
  1995年   10篇
  1994年   10篇
  1993年   8篇
  1992年   12篇
  1991年   11篇
  1990年   7篇
  1989年   3篇
  1988年   3篇
  1987年   8篇
  1985年   3篇
  1984年   4篇
  1983年   3篇
  1979年   6篇
  1977年   2篇
  1976年   3篇
  1970年   2篇
  1969年   1篇
  1968年   2篇
  1966年   1篇
  1956年   2篇
  1955年   1篇
排序方式: 共有886条查询结果,搜索用时 31 毫秒
121.
The onus of proof in criminal cases is beyond any reasonable doubt, and the issue on the lack of complete internal validation data can be manipulated when it comes to justifying the validity and reliability of the X-chromosomal short tandem repeats analysis for court representation. Therefore, this research evaluated the efficiency of the optimized 60% reduced volumes for polymerase chain reaction (PCR) amplification using the Qiagen Investigator® Argus X-12 QS Kit, as well as the capillary electrophoresis (CE) sample preparation for blood samples on Flinder's Technology Associates (FTA) cards. Good-quality DNA profile (3000–12,000 RFU) from the purified blood sample on FTA card (1.2 mm) were obtained using the optimized PCR (10.0 μL of PCR reaction volume and 21 cycles) and CE (9.0 μL Hi-Di™ Formamide and 0.3 μL DNA Size Standard 550 [BTO] and 27 s injection time) conditions. The analytical and stochastic thresholds were 100 and 200 RFU, respectively. Hence, the internal validation data supported the use of the optimized 60% reduced PCR amplification reaction volume of the Qiagen Investigator® Argus X-12 QS Kit as well as the CE sample preparation for producing reliable DNA profiles that comply with the quality assurance standards for forensic DNA testing laboratories, while optimizing the analytical cost.  相似文献   
122.
The storage and use of explosives is regulated at the state and federal level, with a particular focus on physical security and rigorous accounting of the explosive inventory. For those working with explosives for the training and testing of explosive-detecting canines, cross-contamination is an important concern. Hence, explosives intended for use with canine teams must be placed into secondary storage containers that are new, clean, and airtight. A variety of containers meet these requirements and include screw-top glass jars (e.g., mason jars). However, an additional need from the explosive-detecting canine community is secondary containers that can also be used as training aids whereby the volatiles emitted by explosives are emitted in a predictable and stable manner. Currently, a generally accepted method for the storage of explosives and controlled emission of explosive vapor for canine detection does not exist. Ideally, such containers should allow odor to escape from the training aid but block external contaminates such as particulates or other volatiles. One method in use places the explosive inside a permeable cotton bag when in use for training and then stores the cotton bag inside an impermeable nylon bag for long-term storage. This paper describes the testing of an odor permeable membrane device (OPMD) as a new way to store and deploy training aids. We measured the evaporation rate and flux of various liquid explosives and volatile compounds that have been identified in the headspace of actual explosives. OPMDs were used in addition to traditional storage containers to monitor the contamination and degradation of 14 explosives used as canine training aids. Explosives were stored individually using traditional storage bags or inside an OPMD at two locations, one of which actively used the training aids. Samples from each storage type at both locations were collected at 0, 3, 6, and 9 months and analyzed using Fourier Transform Infrared (FTIR) Spectroscopy and Gas Chromatography–Mass Spectrometry (GC–MS) with Solid-Phase Microextraction (SPME). FTIR analyses showed no signs of degradation. GC–MS identified cross-contamination from ethylene glycol dinitrate (EGDN) and/or 2,3-dimethyl-2,3-dinitrobutane (DMNB) across almost all samples regardless of storage condition. The contamination was found to be higher among training aids that were stored in traditional ways and that were in active use by canine teams.  相似文献   
123.
Recently, digital forensics has become increasingly important as it is used by investigation agencies, corporate, and private sector. To supplement the limitations of evidence capacity and be recognized in court, it is essential to establish an environment that ensures the integrity of the entire process ranging from collecting and analyzing to submitting digital evidence to court. In this study, common elements were extracted by comparing and analyzing ISO/IEC 17025, 27001 standards and Interpol and Council of Europe (CoE) guidelines to derive the necessary components for building a digital forensic laboratory. Subsequently, based on 21 digital forensic experts in the field, Delphi survey and verifications were conducted in three rounds. As a result, 40 components from seven areas were derived. The research results are based on the establishment, operation, management, and authentication of a digital forensics laboratory suitable for the domestic environment, with added credibility through collection of the opinions of 21 experts in the field of digital forensics in Korea. This study can be referred to in establishing digital forensic laboratories in national, public, and private digital forensic organizations as well as for employing as competency measurement criteria in courts to evaluate the reliability of the analysis results.  相似文献   
124.
This work presents a data survey regarding the qualitative chemical analysis of drugs seized by the Police in the state of Minas Gerais between July 2017 and June 2022, including an evaluation of labeling of 265 samples of anabolic androgenic steroids (AAS) seized in 2020. The Active Pharmaceutical Ingredients (API) present in the samples were identified through chemical analysis and classified by system Anatomical Therapeutic Chemical (ATC) methods. Analysis of the labeling information for 265 samples of AAS followed the guidance of legislation RDC 71 (2009) from ANVISA. For this study 6355 seized pharmaceuticals underwent qualitative chemical analysis that corresponded to 7739 APIs successfully identified and classified. Among the components studied AAS, psychostimulants, anesthetics, and analgesics were the most commonly examined. AAS seized and tested increased by over 100% and for the majority of the samples analyzed were found to not match the labeling on the packaging. In the meantime, anti-obesity drugs presented a prominent increase of 400% from 2020/1 to 2021/2, during covid-19 quarantine. Seized pharmaceuticals and tests can support information in the planning of public health and safety policies.  相似文献   
125.
Human hairs are one of the most commonly encountered items of trace evidence. Currently, conventional methods for hair analysis include microscopic comparison and DNA analysis (nuclear and mitochondrial). Each approach has its own drawbacks. Hair proteins are stable and offer an alternative to DNA testing, as demonstrated with proteomics for distinguishing humans. However, proteomics is complicated and requires identifying peptides to remain intact following harsh sample preparation methods. Alternatively, the actual amino acid content of a hair sample may also offer important identifying information and actually requires proteins and peptides to be broken down completely rather than remaining intact. This study evaluated the discriminating power of using hair amino acid ratios to differentiate hair samples from 10 unrelated individuals with dark colored hair. Hair proteins were digested, derivatized, and analyzed using gas chromatography–mass spectrometry. Amino acid ratios were calculated for each individual and comparisons using ANOVA and post-hoc pairwise t-test with Bonferroni correction were made with amino acid ratios for individuals. Overall, out of the 45 possible pairwise comparisons between all hair samples, 38 (84%) were differentiable. Out of the 36 possible pairwise comparisons between brown haired individuals, 32 (89%) were considered differentiable using univariate statistics. Multivariate statistics were also attempted but, overall, univariate models were sufficient for exclusionary purposes. These results indicate that amino acid ratio analysis can potentially be used as an exclusionary method using hair if DNA analysis cannot be performed, or to corroborate conclusions made following microscopic analysis.  相似文献   
126.
Illicit fentanyl has flooded the United States' drug market, increasing the risk of overdose and poisonings throughout the general population and accidental exposure among law enforcement officers confiscating the increasing number of seizures. Fentanyl test strips (FTS) are used to obtain presumptive information about the presence of fentanyl in a suspected sample. However, their adoption by law enforcement personnel and seized-drug analysts has been limited because most products are advertised for urine testing, not for assays using water solutions. This study presents an evaluation of four commercial FTS: Rapid Response from BTNX, Inc.; T-Dip Fentanyl (FTY) Urine Dip Cards obtained from Amazon.com ; Premier BioDip FYL10 from Premier Biotech Inc.; and MobileDetect Fentanyl strips from DetectaChem, Inc. Performance characteristics curves were used to compare the products' sensitivity, showing that all can reliably detect fentanyl in aqueous solutions at concentrations below 1 μg/mL, with some of the tests able to reliably detect the drug at 200 ng/mL. A stability study demonstrates the performance of all four FTS brands was only slightly affected after 30 days of storage at two extreme environmental conditions. Fentanyl-related substances are also evaluated using the Rapid Response FTS, which showed high cross-reactivity with para-fluorofentanyl and acetylfentanyl, but lower with ortho-chlorofentanyl, carfentanil, and 4-ANPP. Users should be aware that FTS may give false-negative results even when potentially dangerous levels of carfentanil are present. When testing other common drugs, adulterants, and diluents frequently encountered in seized tablets, concentration-dependent results were obtained and multiple instances of false positives were recorded.  相似文献   
127.
128.
Public management is a domain of research that is now roughly three decades old. Researchers in this area have made important advances in understanding about the performance of public organizations. But questions have been raised about the scope and methods of public management research (PMR). Does it neglect important questions about the development of major institutions of the modern state? Has it focused unduly on problems of the advanced democracies? Has it made itself irrelevant to public debates about the role and design of government, and the capacity of public institutions to deal with emerging challenges? This set of eight short essays were prepared for a roundtable held at the research conference of the PMR Association at the University of Aarhus in June 2016. Contributors were asked to consider the question: Is PMR neglecting the state?  相似文献   
129.
130.
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