全文获取类型
收费全文 | 24996篇 |
免费 | 1233篇 |
专业分类
各国政治 | 904篇 |
工人农民 | 1751篇 |
世界政治 | 1300篇 |
外交国际关系 | 807篇 |
法律 | 16548篇 |
中国共产党 | 2篇 |
中国政治 | 104篇 |
政治理论 | 4724篇 |
综合类 | 89篇 |
出版年
2023年 | 76篇 |
2021年 | 90篇 |
2020年 | 430篇 |
2019年 | 449篇 |
2018年 | 1744篇 |
2017年 | 1696篇 |
2016年 | 1595篇 |
2015年 | 564篇 |
2014年 | 546篇 |
2013年 | 1825篇 |
2012年 | 651篇 |
2011年 | 1352篇 |
2010年 | 1468篇 |
2009年 | 1090篇 |
2008年 | 1185篇 |
2007年 | 1137篇 |
2006年 | 527篇 |
2005年 | 496篇 |
2004年 | 598篇 |
2003年 | 492篇 |
2002年 | 429篇 |
2001年 | 672篇 |
2000年 | 606篇 |
1999年 | 480篇 |
1998年 | 248篇 |
1997年 | 182篇 |
1996年 | 208篇 |
1995年 | 212篇 |
1994年 | 187篇 |
1993年 | 176篇 |
1992年 | 305篇 |
1991年 | 311篇 |
1990年 | 296篇 |
1989年 | 276篇 |
1988年 | 305篇 |
1987年 | 262篇 |
1986年 | 320篇 |
1985年 | 316篇 |
1984年 | 255篇 |
1983年 | 233篇 |
1982年 | 182篇 |
1981年 | 154篇 |
1980年 | 145篇 |
1979年 | 224篇 |
1978年 | 122篇 |
1977年 | 99篇 |
1975年 | 94篇 |
1974年 | 124篇 |
1973年 | 80篇 |
1972年 | 78篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
Christine M. Wienke Totura Marc S. Karver Ellis L. Gesten 《Journal of youth and adolescence》2014,43(1):40-52
Peer victimization is a well-known national and international problem, contributing to a range of emotional, social, and behavioral consequences. Using structural equation modeling, the authors tested a theoretical model suggesting that psychological distress and student engagement mediate the association between the experience of victimization and concurrent academic achievement. Participants were 469 (46.4 % male, 53.6 % female) 6th to 8th grade students, from randomly selected classrooms in 11 middle schools in a southeastern school district. Structural equation models of the hypothesized effects demonstrated adequate fit to the data, with both symptoms of psychological distress and engagement mediating the relationship between victimization and academic achievement. In general, the results suggest that victimization predicts diminished academic achievement by way of psychological distress and poorer engagement in classroom and academic tasks. However, the direct relationship between victimization and measures of achievement lacked significance across many correlational and path analyses conducted. These findings have implications for researchers and practitioners in understanding how psychological distress and student engagement are associated with the academic performance of students who experience peer victimization. 相似文献
962.
963.
Rosario Barranco M.D. Fiorella Caputo M.D. Davide Bedocchi M.D. Francesca Maria Elena Frigiolini M.D. Lara Castelletti M.D. Giulio Fraternali Orcioni M.D. Francesco Ventura M.D. Ph.D. 《Journal of forensic sciences》2020,65(1):314-317
Intravascular lymphoma (IVL) is a rare subtype of extranodal lymphomas that is characterized by the selective growth of neoplastic cells within the lumen of small vessels. Authors document the case of an unexpected death caused by an undiagnosed intravascular large B-cell lymphoma with multi-organ involvement, which had initially manifested as an infection and then as an unclarified central nervous system pathology. Histological examination showed a diffuse intravascular large B-cell brain lymphoma with prominent cerebral involvement. The relevance of the case report reveals the importance of an autopsy of an extremely rare and threatening pathology that in most cases is diagnosed only postmortem. As a result, the role of the forensic pathologist becomes particularly important. When specifically performing an in-depth autopsy evaluation with a specific histologic analysis, it is possible to identify the intravascular lymphoma and declare a more accurate cause of death. 相似文献
964.
965.
Jennifer Paola Pascali Ph.D. Diego Palumbo M.Sc. Federica Umani Ronchi Ph.D. Francesco Mari Ph.D. Alessia Fioravanti M.Sc. Elisabetta Bertol Ph.D. 《Journal of forensic sciences》2020,65(1):189-192
Through the measurement of ethyl glucuronide in hair (hETG), it is possible to assess chronic alcohol abuse over time. In this paper, we present a study on hETG in Italian prison inmates. Analyses were performed by LC-MS according to a previously published method. Results were evaluated using the cut-offs established by the Society of Hair Testing. Positives samples (ETG > 30 pg/mg) accounted for 6% of all subjects, with concentrations ranging from 42 pg/mg up to 270 pg/mg, abstinent subjects (ETG < 7 pg/mg) accounted for 88%, and moderate alcohol consumption (7 < ETG < 30 pg/mg) for 6% of the subjects. No females displayed ETG values above 30 pg/mg. Among positive samples, only two subjects did not declare heavy alcohol consumption and were found strongly positive at 210 and 270 pg/mg. To the best of our knowledge, this represents the first study on ETG hair concentration on prison inmates. 相似文献
966.
967.
Barbara Bertoglio M.Sc. Ph.D. Sofia Corradin MS Annalisa Cappella M.Sc. Ph.D. Debora Mazzarelli B.Sc. Lucie Biehler-Gomez M.Sc. Ph.D. Carmelo Messina M.D. Grazia Pozzi M.D. Luca Maria Sconfienza M.D. Ph.D. Francesco Sardanelli M.D. Chiarella Sforza M.D. Ph.D. Danilo De Angelis D.D.S. Ph.D. Cristina Cattaneo M.D. Ph.D. 《Journal of forensic sciences》2020,65(6):2098-2107
Many studies in the literature have highlighted the utility of virtual 3D databanks as a substitute for real skeletal collections and the important application of radiological records in personal identification. However, none have investigated the accuracy of virtual material compared to skeletal remains in nonmetric variant analysis using 3D models. The present study investigates the accuracy of 20 computed tomography (CT) 3D reconstruction models compared to the real crania, focusing on the quality of the reproduction of the real crania and the possibility to detect 29 dental/cranial morphological variations in 3D images. An interobserver analysis was performed to evaluate trait identification, number, position, and shape. Results demonstrate a false bone loss in 3D models in some cranial regions, specifically the maxillary and occipital bones in 85% and 20% of the samples. Additional analyses revealed several difficulties in the detection of cranial nonmetric traits in 3D models, resulting in incorrect identification in circa 70% of the traits. In particular, pitfalls included the detection of erroneous position, error in presence/absence rates, in number, and in shape. The lowest percentages of correct evaluations were found in traits localized in the lateral side of the cranium and for the infraorbital suture, mastoid foramen, and crenulation. The present study highlights important pitfalls in CT scan when compared with the real crania for nonmetric analysis. This may have crucial consequences in cases where 3D databanks are used as a source of reference population data for nonmetric traits and pathologies and during bone-CT comparisons for identification purposes. 相似文献
968.
Emily E. Fairbanks M.S. Jennifer Turner M.S. Junkun Ma Ph.D. Jorn Yu Ph.D. 《Journal of forensic sciences》2020,65(6):1954-1960
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
969.
Mohammed A. Almazrouei M.Sc. Itiel E. Dror Ph.D. Ruth M. Morgan D.Phil. 《Journal of forensic sciences》2020,65(6):1968-1977
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
970.
Selena McKay-Davis M.F.S. Tharinia Robinson Ph.D. Ismail M. Sebetan M.D. Ph.D. Paul Stein Ph.D. 《Journal of forensic sciences》2020,65(6):2065-2070
Forensic Technicians provide crime scene investigation services and are exposed to stressful violent crimes, motor vehicle accidents, biological or chemical hazards, and other appalling imagery. Forensic Technicians would likely experience physical and psychological stress after exposure to trauma, and security vulnerabilities similar to Sworn Police Officers. The perceived availability of mental health resources, job-related physical, psychological stress, and traumatic experiences of both Forensic Technicians and Sworn Police Officers from California law enforcement agencies were investigated using a self-reported survey. Responses were evaluated for any significant differences in the perceived stress, job-related physical stress, and resulting psychological impact affecting the participants. The survey contained a mix of True/False, Circle/Check the Appropriate Box, or Likert Scale (1–5) responses. The results were evaluated statistically and discussed. Results indicated Sworn Police Officers and Forensic Technicians have different on-duty stress levels, but similar off-duty stress levels. Nearly two-thirds of 54 job-related stressors were not significantly different between the two occupations. However, Forensic Technicians reported more adverse effects in 17 physical and psychological job-related activities compared with Sworn Police Officers. Forensic Technicians reported lower awareness levels and availability of agency mental health support services than were reported by Sworn Police Officers. This study reports for the first time an unexpected outcome that perceived and job-related psychological stress is greater for Forensic Technicians than Sworn Police Officers. Possible reasons for this disparity will be discussed as well as stress management tools that should be implemented to reduce health risk factors for both career professionals as well as increase public safety. 相似文献