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   1493篇
  免费   113篇
各国政治   15篇
工人农民   33篇
世界政治   13篇
外交国际关系   60篇
法律   892篇
中国共产党   97篇
中国政治   118篇
政治理论   46篇
综合类   332篇
  2024年   4篇
  2023年   25篇
  2022年   11篇
  2021年   21篇
  2020年   59篇
  2019年   33篇
  2018年   40篇
  2017年   72篇
  2016年   78篇
  2015年   40篇
  2014年   155篇
  2013年   186篇
  2012年   133篇
  2011年   139篇
  2010年   80篇
  2009年   100篇
  2008年   78篇
  2007年   75篇
  2006年   58篇
  2005年   61篇
  2004年   35篇
  2003年   41篇
  2002年   27篇
  2001年   26篇
  2000年   12篇
  1999年   3篇
  1998年   1篇
  1997年   1篇
  1996年   1篇
  1995年   1篇
  1994年   2篇
  1985年   4篇
  1984年   3篇
  1983年   1篇
排序方式: 共有1606条查询结果,搜索用时 15 毫秒
201.
高等教育大众化对校园文化建设提出了新的要求。大众化教育背景下,校园文化建设应把握好主体性设计、群众性参与性和综合性评价原则,推行项目化运作,尤其是要抓好学生社团、网络和社会实践这三个载体,同时要建管协调,堵疏结合,牢牢把握校园文化建设的主动权,充分发挥校园文化的育人功能,推动校园文化健康发展。  相似文献   
202.
实践永无止境,创新永无止境,研究永无止境。从历史的角度探讨信访制度的道路,寻求信访制度变迁的过程及其所遇困难的根源,对当前信访制度的改革具有极其重要的现实意义。  相似文献   
203.
The deposition of methamphetamine within indoor environments due to illegal activities can pose a health risk for occupants. Current cleaning techniques are costly and inefficient, calling for the development of alternative remediation methods. In addition, the fate of methamphetamine in indoor environments is largely unknown, negatively impacting our knowledge on the health risks associated with contaminated dwellings. Under the conditions of this study, 97% of surface deposited methamphetamine on a paper substrate was consumed after 12 min of exposure to ozone, thus demonstrating potential for its use as a remediation agent. The reaction had an effective second‐order rate constant with an upper limit of 2.15 ± 1 × 10?18 cm3/molecule/s, and the main product observed was phenyl‐2‐propanone (P2P) at 8.3% yield, as determined using GC/MS. Several products observed in this study have also been reported as by‐products of methamphetamine synthesis, including P2P—a known methamphetamine precursor, which indicates that their detection at a potential clandestine site is not necessarily evidence of manufacture.  相似文献   
204.
Carbon‐based materials are often used as matrices for matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) and its imaging (MALDI‐MSI). However, researchers have refrained from using carbon‐based fingerprint powder (CFP) as a matrix due to high background and contamination. In this work, the compatibility of CFP is reevaluated with MALDI‐MSI using a high‐resolution mass spectrometer (HRMS) and compared to traditional organic matrices. Relevant fingerprint compounds were easily distinguished from carbon cluster peaks when using HRMS. For fair comparison, half of a fingerprint was dusted with CFP while the other half was dusted with traditional organic matrices. All compounds studied had comparable, or higher, signal‐to‐noise (S/N) ratios when CFP was used as the matrix. Additionally, chemical image qualities closely followed the trend of S/N ratios. CFP proved to be an effective one‐step development and matrix application technique for MALDI‐MSI of latent fingerprints, when carbon cluster peaks are well separated by a HRMS.  相似文献   
205.
Pregabalin is a Schedule V controlled substance which is defined as the (S) enantiomer of 3‐(aminomethyl)‐5‐methylhexanoic acid. It is used legitimately to treat neuropathy in patients with diabetes as well as for epilepsy and fibromyalgia. Pregabalin is an amino acid and an amphoteric compound, which makes it difficult to analyze using the conventional GC‐MS instrumentation found in most forensic drug analysis laboratories. Problems associated with the traditional GC‐MS analysis of pregabalin include selective solubility, ring closure to the corresponding lactam in the GC injection port and/or the MS transfer line and difficulty with chiral derivatization due to the presence of a carboxylic acid moiety. Here, we show that these challenges can be overcome by methylating (capping) the carboxylic acid portion of the pregabalin molecule and converting to the corresponding methyl ester. Once the methyl ester is synthesized, chiral derivatization at the amine can be achieved to identify the controlled (S) enantiomer of pregabalin via GC‐MS.  相似文献   
206.
In several medico‐legal cases, bone samples analysis may provide the only source of toxicological information. This case study reports the analysis of a human bone specimen, belonging to a 46‐year‐old man, found 3 months after his death due to cervical–thoracic injuries in a motorcycle accident. Bone specimen was the only available material for toxicological analysis, among few skull hair and rotten skin. Analysis was performed by a newly developed and validated ultra‐high‐pressure liquid chromatography–mass spectrometry/mass spectrometry (UHPLC‐MS/MS) method, following simple and efficient sample pretreatment. The results were in accordance with the man's medical record: Alprazolam and zolpidem were found at 2.2 and 5.4 ng/g of bone, respectively. Both these drugs were prescribed to the deceased.  相似文献   
207.
Fentanyl transdermal patches have been used to treat cancer‐ and noncancer‐related chronic pain. However, its inappropriate or illegal application may cause fatal poisoning. We herein present the case of a Japanese woman in her 40s who was found dead with seven 25‐μg/h fentanyl transdermal patches on her body. We established a detailed toxicological analysis procedure to quantify fentanyl, and its metabolite norfentanyl, and other drugs (acetaminophen, allylisopropylacetylurea, celecoxib, estazolam, promethazine, and sertraline) in human whole blood by ultra‐high‐performance liquid chromatography–tandem mass spectrometry. The measured fentanyl and norfentanyl concentrations in the femoral and cardiac blood were 0.051 and 0.072 μg/mL and 0.033 and 0.076 μg/mL, respectively. The decedent's fentanyl concentrations were consistent with previously reported postmortem blood levels for fatal cases of poisoning by fentanyl transdermal patches. Based on the decedent's case history, autopsy findings, and toxicological analyses, the cause of death was identified as intoxication with transdermal fentanyl.  相似文献   
208.
Personality, psychopathology, and motives of 44 surviving offenders committing mass murder in Germany over 25 years (1984–2009) were analyzed using court files and psychiatric expertises. Initially, 123 mass murders in Germany were detected in the time period 1980–2010 (inclusive deceased offenders). Using a data entry form based on ViCLAS (Violent Crime Linkage Analysis System), we categorized the 44 surviving mass murderers into three prototypes using the ‘TwoStep Cluster’-method (separation of the offenders in different groups depending on their similarity of specific items): 1. Narcissistic or aggressive men suffering from addiction or affective disorder, committing mass murder out of rage/hate when being intoxicated by alcohol, 2. Psychotic offenders with schizophrenia and comorbid substance abuse. 3. Aggressive, narcissistic or anxious adolescents, half of them suffering from affective disorder or ADHD, committing mass murder out of rage/hate. Not included are such events where the offenders died and therefore no court files or psychiatric expertises were available. Classification and subtyping of the offenders’ personalities and psychopathological conditions might help to improve the chances for an early detection of persons at risk.  相似文献   
209.
Over the past decades, consume of slimming agents considerably increased in several countries, including Brazil, due to weight-loss and stimulant properties. Since these drugs are controlled to prevent illicit and indiscriminate use, there is a parallel illegal market that uses the Internet and irregular pharmacies in order to distribute these formulations. Slimming agents produced by these illegal sources are known for being manufactured with little or none quality control resulting in uncertain and unknown formulations. For forensic purposes, apprehended pharmaceuticals have to undergo a process of chemical identification that can be difficult due to its complex matrix. In this sense, application of assisted energies in the extraction step such as microwave irradiation can be a promising method to increase the recuperation of the target molecules of the sample. Therefore, the aim of this research was to identify four slimming agents apprehended in Brazil by means of visual inspection, Fourier Transform Infrared Spectroscopy, Differential Scanning Calorimetry and Gas Chromatography – Mass Spectrometry. Moreover, the efficiency of solid-liquid extraction and microwave-assisted extraction was compared. It should be noted that our work was one of the few to use Differential Scanning Calorimetry and the application of microwave irradiation in the analysis of apprehended materials. Results showed that the majority of the samples was counterfeit being composed of one or several adulterants or contaminants. Initially, visual inspection resourcefully screened the slimming agents for possible signs of falsification, however it failed to detect fraudulent products that were very similar to veridical medicines. Sequentially, Fourier Transform Infrared Spectroscopy detected functional groups present in the samples while the presence or absence of the alleged active ingredients were successfully measured with Differential Scanning Calorimetry and, thus, providing a full chemical screening of the apprehended materials. Gas Chromatography- Mass Spectrometry confirmed the presence of adulterants such as caffeine, fluoxetine and phenolphthalein as well as contaminants such as sulfurol in the falsified samples. Finally, comparison of extraction procedures indicated that microwave-assisted extraction increased the recovery of compounds detected in chromatographic analysis to a greater extent than solid-liquid extraction.  相似文献   
210.
In many Western countries, citizen knowledge of terrorist events is intrinsically shaped by the style of broadcasted messages published by the media. Media discourses regarding terrorist acts raise questions about how such rhetoric elicits fear in people who typically experience such events through news reports. However, we do not fully understand the impact of the media on perceptions of terrorism as clearly as we understand the relationship between the media and fear of crime. This study examines how media sources accessed actively (e.g. through newspapers; Internet) or passively (e.g. through television; radio) influence knowledge and fear of terrorism. We find receiving information about terrorism from multiple media sources increases fear of terrorism, but media sources accessed passively are not as influential as media sources accessed more actively. These results highlight how media consumption from various sources may affect one’s fear of terrorism, and further illustrates how the role of perceived knowledge may exacerbate or mitigate fear. Implications for policy and practice are discussed.  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