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   10164篇
  免费   325篇
各国政治   523篇
工人农民   470篇
世界政治   698篇
外交国际关系   379篇
法律   6187篇
中国共产党   3篇
中国政治   70篇
政治理论   2077篇
综合类   82篇
  2020年   125篇
  2019年   173篇
  2018年   260篇
  2017年   280篇
  2016年   264篇
  2015年   184篇
  2014年   192篇
  2013年   1164篇
  2012年   282篇
  2011年   279篇
  2010年   223篇
  2009年   251篇
  2008年   315篇
  2007年   286篇
  2006年   300篇
  2005年   286篇
  2004年   284篇
  2003年   259篇
  2002年   261篇
  2001年   293篇
  2000年   298篇
  1999年   224篇
  1998年   136篇
  1997年   134篇
  1996年   123篇
  1995年   114篇
  1994年   122篇
  1993年   129篇
  1992年   196篇
  1991年   216篇
  1990年   191篇
  1989年   187篇
  1988年   169篇
  1987年   187篇
  1986年   184篇
  1985年   173篇
  1984年   165篇
  1983年   176篇
  1982年   104篇
  1981年   100篇
  1980年   86篇
  1979年   111篇
  1978年   79篇
  1977年   84篇
  1976年   64篇
  1975年   64篇
  1974年   65篇
  1973年   74篇
  1972年   64篇
  1968年   55篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A comparison of three groups of Title IV-E child welfare workers revealed significant differences among all groups on job expectations and career goals. New workers reported most positive expectations for their jobs, and greatest interest in child welfare careers and in pursuing educational goals. Seasoned workers expressed least positive expectations and least interest in future child welfare careers and educational goals. Findings may assist universities in student selection and curriculum. Child welfare agencies may benefit in areas of recruitment, training, and policies. Realistic job previews might moderate high expectations for new workers and reduce unmet expectations for experienced workers.  相似文献   
992.
993.
Volatile organic compounds (VOCs) are by-products of cadaveric decomposition and are responsible for the odor associated with decomposing remains. The direct link between VOC production and individual postmortem microbes has not been well characterized experimentally. The purpose of this study was to profile VOCs released from three postmortem bacterial isolates (Bacillus subtilis, Ignatzschineria indica, I. ureiclastica) using solid-phase microextraction arrow (SPME Arrow) and gas chromatography–mass spectrometry (GC-MS). Species were inoculated in headspace vials on Standard Nutrient Agar and monitored over 5 days at 24°C. Each species exhibited a different VOC profile that included common decomposition VOCs. VOCs exhibited upward or downward temporal trends over time. Ignatzschineria indica produced a large amount of dimethyldisulfide. Other compounds of interest included alcohols, aldehydes, aromatics, and ketones. This provides foundational data to link decomposition odor with specific postmortem microbes to improve understanding of underlying mechanisms for decomposition VOC production.  相似文献   
994.
Microbial communities have potential evidential utility for forensic applications. However, bioinformatic analysis of high-throughput sequencing data varies widely among laboratories. These differences can potentially affect microbial community composition and downstream analyses. To illustrate the importance of standardizing methodology, we compared analyses of postmortem microbiome samples using several bioinformatic pipelines, varying minimum library size or minimum number of sequences per sample, and sample size. Using the same input sequence data, we found that three open-source bioinformatic pipelines, MG-RAST, mothur, and QIIME2, had significant differences in relative abundance, alpha-diversity, and beta-diversity, despite the same input data. Increasing minimum library size and sample size increased the number of low-abundant and infrequent taxa detected. Our results show that bioinformatic pipeline and parameter choice affect results in important ways. Given the growing potential application of forensic microbiology to the criminal justice system, continued research on standardizing computational methodology will be important for downstream applications.  相似文献   
995.
Establishing error rates is crucial for knowing how well one is performing, determining whether improvement is needed, measuring whether interventions are effective, as well as for providing transparency. However, the flurry of activities in establishing error rates for the forensic sciences has largely overlooked some fundamental issues that make error rates a problematic construct and limit the ability to obtain a meaningful error rate. These include knowing the ground truth, establishing appropriate databases, determining what counts as an error, characterizing what is an acceptable error rate, ecological validity, and transparency within the adversarial legal system. Without addressing these practical and theoretical challenges, the very notion of a meaningful error rate is limited.  相似文献   
996.
Postmortem computed tomography (PMCT) is integrated into the evaluation of decedents in several American medical examiner offices and medicolegal death investigative centers in many other countries. We retrospectively investigated the value of PMCT in a series of firearm homicide cases from a statewide centralized medical examiner’s office that occurred during 2016. Autopsies were performed or supervised by board-certified forensic pathologists who reviewed the PMCT scans prior to autopsy. PMCT scans were re-evaluated by a forensic radiologist blinded to the autopsy findings and scored by body region (head–neck, thoracoabdominal, and extremities). Injury discrepancies were scored using a modified Goldman classification and analyzed with McNemar’s test. We included 60 males and 20 females (median age 31 years, range 3–73). Based on PMCT, 56 (79.1%) cases had injuries relevant to the cause of death in a single body region (24 head–neck region, 32 thoracoabdominal region). Out of these 56 cases, 9 had a missed major diagnosis by PMCT outside that region, including 6 extremity injuries visible during standard external examination. Yet all had evident lethal firearm injury. We showed that PMCT identifies major firearm injuries in homicide victims and excludes injuries related to the cause of death in other regions when a single body region is injured. Although PMCT has a known limited sensitivity for soft tissue and vascular pathology, it can be combined with external examination to potentially reduce or focus dissections in some of these cases depending on the circumstances and medicolegal needs.  相似文献   
997.
Trigger pull is the force that needs to be exerted on the trigger to discharge a firearm. The measurement of trigger pull can assist in the evaluation of the safety, function, and manufacturing characteristics associated with a firearm during the forensic firearm examination process. Nonetheless, the accuracy and uncertainty of trigger pull measurements may be affected by the measuring device, test procedure, and environmental conditions. In this work, an innovative finger-trigger interface device was developed to facilitate accurate trigger pull measurements. The idea was to reduce the variation related to the position of the measurement device on the trigger in existing measuring methods and devices. Three force sensors based on different technologies were initially evaluated. While two of the three sensors failed to produce data, the miniature capacitive plate sensor exhibited high precision and a linear response over the range of typical trigger pulls. To examine the effects of the finger-trigger interface on trigger pull measurement, different sensor housing prototypes were designed in silico and 3D printed for the construction of three finger-trigger interface devices. The performance of each finger-trigger interface device was evaluated by measuring the trigger pulls of several selected firearms and comparing the data to a previously published study. Our preliminary results demonstrated the novel finger-trigger interface device offered a new way to measure trigger pull in situ with acceptable accuracy and precision.  相似文献   
998.
Although forensic examiners operate in a stressful environment, there is a lack of understanding about workplace stress and feedback. These organizational and human factors can potentially impact forensic science judgments. In this study, 150 practicing forensic examiners from one laboratory were surveyed about their experiences of workplace stress, and the explicit and implicit feedback they receive. Forensic examiners reported that their high stress levels originated more from workplace-related factors (management and/or supervision, backlogs, and the pressure to do many cases) than from personal related factors (family, medical, and/or financial). The findings showed that a few (8%) of the forensic examiners sometimes felt strong implicit feedback about what conclusions were expected from them and that some (14%) also strongly felt that they were more appreciated when they helped to solve a case (e.g., by reaching a “match” as opposed to an “inconclusive” conclusion). Differences were found when comparing workplace stress and feedback levels across three core forensic science fields (forensic biology, chemistry, and latent prints) and across career stages (early, mid, and late). Gaining insights into the stress factors within a workplace and explicit and implicit feedback has implications for developing policies to improve the well-being, motivation, and performance of forensic examiners.  相似文献   
999.
Disparities between federal and state cannabis regulation, coupled with protracted federal enforcement, have facilitated the proliferation of a multi–billion dollar cannabis industry that generally evades compliance with federal consumer protection laws. The Federal Food, Drug and Cosmetic Act (FDCA) established regulatory pathways for the lawful development of products such as food, drugs, and dietary supplements. The FDCA uses a science-based approach to protect consumers from harmful products, but early inconsistencies between state and federal cannabis regulation prevented and/or discouraged the cannabis industry from complying with FDCA requirements. Cannabis products are promoted as safe and attributed with providing effective therapeutic treatment for numerous medical conditions, yet the claims often lack the rigorous evidence-based support typically expected by regulators and the medical community. The Food and Drug Administration (FDA) has announced its expectation that cannabidiol (CBD) products comply with the FDCA and follow a science-based approach to product development. The FDA is addressing violations involving unsubstantiated CBD health claims and is working to clarify the future regulatory pathway for CBD products. Meanwhile, the state-approved cannabis market continues to operate, selling numerous products that have circumvented the FDCA consumer protections. This article examines the need for strengthening consumer protections in the cannabis market. We use evidence-based medicine as a model to address the importance of science-based product development and to contextualize a science-based comparison of regulatory pathways for cannabis drugs, food, and dietary supplements.  相似文献   
1000.
Journal of Experimental Criminology - Examine how the amount and makeup of police-initiated activities changed after the introduction of body-worn cameras (BWCs). From May 21 to November 22, 2016,...  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