全文获取类型
收费全文 | 7702篇 |
免费 | 525篇 |
专业分类
各国政治 | 369篇 |
工人农民 | 274篇 |
世界政治 | 554篇 |
外交国际关系 | 284篇 |
法律 | 5214篇 |
中国政治 | 42篇 |
政治理论 | 1452篇 |
综合类 | 38篇 |
出版年
2023年 | 43篇 |
2020年 | 175篇 |
2019年 | 194篇 |
2018年 | 217篇 |
2017年 | 259篇 |
2016年 | 242篇 |
2015年 | 223篇 |
2014年 | 213篇 |
2013年 | 823篇 |
2012年 | 184篇 |
2011年 | 186篇 |
2010年 | 224篇 |
2009年 | 237篇 |
2008年 | 190篇 |
2007年 | 179篇 |
2006年 | 173篇 |
2005年 | 174篇 |
2004年 | 189篇 |
2003年 | 171篇 |
2002年 | 152篇 |
2001年 | 324篇 |
2000年 | 257篇 |
1999年 | 233篇 |
1998年 | 100篇 |
1997年 | 73篇 |
1996年 | 72篇 |
1995年 | 86篇 |
1994年 | 94篇 |
1993年 | 95篇 |
1992年 | 155篇 |
1991年 | 159篇 |
1990年 | 147篇 |
1989年 | 159篇 |
1988年 | 128篇 |
1987年 | 140篇 |
1986年 | 126篇 |
1985年 | 133篇 |
1984年 | 106篇 |
1983年 | 119篇 |
1982年 | 82篇 |
1981年 | 78篇 |
1980年 | 56篇 |
1979年 | 108篇 |
1978年 | 70篇 |
1977年 | 60篇 |
1976年 | 52篇 |
1975年 | 49篇 |
1974年 | 59篇 |
1973年 | 57篇 |
1972年 | 44篇 |
排序方式: 共有8227条查询结果,搜索用时 31 毫秒
201.
Marloes E. M. Vester M.D. Ph.D. Kurt B. Nolte M.D. Ph.D. Gary M. Hatch M.D. Chandra Y. Gerrard M.P.H. B.S. Reinoud D. Stoel Ph.D. Rick R. van Rijn M.D. Ph.D. 《Journal of forensic sciences》2020,65(5):1568-1573
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
202.
Adam Lanzarotta Ph.D. Michael D. Thatcher B.S. Lisa M. Lorenz B.S. JaCinta S. Batson M.S. 《Journal of forensic sciences》2020,65(5):1443-1449
A simple, quick, selective, sensitive, and effective field-friendly method capable of being used by nonexperts has been developed for detecting mitragynine in Mitragyna speciosa (kratom) using surface-enhanced Raman spectroscopy (SERS). Over 100 samples and blanks (known to be either positive or negative for the presence of mitragynine) were examined in duplicate using five identical handheld Raman spectrometers, which provided a data set of over 1,000 examinations. Based on the results of these analyses, the method yielded a true-positive rate of 99.3%, a true-negative rate of 97.9%, a false-positive rate of 2.1%, and a false-negative rate of 0.7%. The average minimum detectable concentration (Cm) of mitragynine that reproducibly yielded a match for one of the library spectra on all five instruments was determined to be 342 ng/mL (ppb). This Cm value is a conservative estimate considering that the extraction process was not fully optimized by this study, which was not necessary since the Cm value achieved was well below typical mitragynine concentrations in kratom (1.3–2.3%). The method is ideal (i) for prioritizing samples for additional testing using other more time-consuming laboratory-based techniques needed to detect and quantify mitragynine and (ii) for field use at international mail facility (IMF) satellite laboratories to help interdict kratom and prevent this dangerous product from reaching the U.S. supply chain. 相似文献
203.
Dalia M. Al-Saif M.B.B.S. S.B.F.L.M. Maram A. Al-Farayedhi M.B.B.S. S.B.F.L.M Ghadah A. Al-Shamsi M.B.B.S. S.B.F.L.M. Marwah I. Al-Bayat M.B.B.S. S.B.F.L.M. Osama M. Almadani M.D. Ph.D. F.F.F.L.M. Magdy A. Kharoshah M.B.Bch. M.Sc. M.D F.F.F.L.M. 《Journal of forensic sciences》2020,65(5):1574-1578
Examination of the female external genitalia to assess for sexual abuse is performed in living individuals, and the interpretation of the findings is based on evidence-based studies. However, in the deceased, no such studies are available, and postmortem changes could present as suspicious findings that can be mistaken for trauma. Patches of discoloration in the hymen were reported previously in one case as hypostasis (i.e., livor and lividity), and based on this finding, it was listed as a finding that is not associated with trauma. This was a retrospective study that was conducted in the Center of Forensic and Legal Medicine in Dammam, Saudi Arabia over a 4-year period. The study included 30 deceased women in whom photographic documentation of their external genitalia was assessed for postmortem changes. The postmortem interval ranged from less than 24 h to more than 100 days, and the ages of these deceased women were in the 20–40 year-old age group. In cases where the hymen, vagina, and/or fossa navicularis were clearly visible, none of these areas showed any hypostatic discoloration. A comparison between antemortem and postmortem appearance of the hymen in one case clearly showed the absence of hypostatic changes in the hymen. In conclusion, any discoloration of the external genitalia that is detected in a female decedent requires serious consideration. 相似文献
204.
When a bullet punctures a surface, it leaves behind a bullet impact, which can be analyzed in order to determine the origin and trajectory path from which a bullet was discharged using many different scientific methods to reconstruct a shooting scene. The purpose of the research was to test the accuracy and repeatability of reconstructing the impact angle of single bullet impacts using the ellipse method. The research was conducted by firing various calibers of ammunition into drywall panels positioned at varying angles of incidence from 88° until ricochet occurred. This was done in order to determine which caliber type and angle of incidence are most accurate and precise for reconstructing a shooting scene. The study examined four caliber types fired into drywall panels, with 5 repeated shots for each of the 11 angles of incidence (n = 220). Furthermore, 31 participants partook in the study to estimate a bullet impact angle of incidence utilizing the ellipse method. The results show that the best performance (accuracy and repeatability) is seen with the measurements of the 0.45 caliber ammunition. When angle of incidences is low (<64°), the performance (accuracy and repeatability) was seen to be better in all caliber ammunitions. Overall, the data provided for single bullet impacts deposited in drywall show that the ellipse method is useful in providing measurements for most crime scene reconstruction purposes and has also demonstrated that results vary depending on the type of ammunition, firearm, and angle of incidence being examined. 相似文献
205.
206.
Sophia K. Chiu M.D. M.P.H. Jessica F. Li M.S.P.H. Kurt B. Nolte M.D. 《Journal of forensic sciences》2020,65(4):1324-1327
Recent increases in deaths in the United States from synthetic opioids such as fentanyl and fentanyl analogues (fentanyls) have raised concerns about possible occupational exposures to these potent agents. Medicolegal death investigators and autopsy suite staff might perform job tasks involving exposure to fentanyls. The potential for exposure to fentanyls among medicolegal death investigators and autopsy technicians at a state medical examiner's office was evaluated through review of caseload characteristics, injury and illness logs, and procedures and policies and discussions with management and employee representatives. The evaluation showed that this medical examiner's office had low potential for work-related exposure to fentanyls; its standard operating procedures and personal protective equipment requirements should reduce the potential for occupational exposure. Medicolegal death investigation agencies can develop and implement guidance to control exposures and provide workforce education and training to reduce the potential for work-related exposure to fentanyls. 相似文献
207.
208.
Raymond B. Firehock John A. Gentry Julia W. Rogers James M. Simon Jr 《Intelligence & National Security》2018,33(5):774-783
The literature on intelligence analysis contains many references to the ‘review process’, the mechanism by which analysts’ drafts are converted into corporate products. Analysts whose drafts consistently navigate the process quickly and smoothly are regarded as star performers. Divining the practical meaning of organizational definitions of ‘good’ analysis and the personal preferences of specific senior reviewers is not easy, however. Analysts occasionally commit their understanding of reviewers’ stylistic preferences to paper, effectively providing style guides to help others. This essay presents and explains the development and implications of one such guide, which was designed to help analysts in CIA’s Office of Strategic Research in the early 1970s. 相似文献
209.
What Levels of Racial Diversity Can Be Achieved with Socioeconomic‐Based Affirmative Action? Evidence from a Simulation Model
下载免费PDF全文
![点击此处可从《Journal of policy analysis and management》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Sean F. Reardon Rachel Baker Matt Kasman Daniel Klasik Joseph B. Townsend 《Journal of policy analysis and management》2018,37(3):630-657
This paper investigates to what extent socioeconomic status (SES)‐based affirmative action in college admissions can produce racial diversity. Using simulation models, we investigate the racial and socioeconomic distribution of students among colleges under the use of race‐ or SES‐based affirmative action policies, or targeted, race‐based recruitment policies. We find, first, that neither SES‐based affirmative action nor race‐targeted recruiting on their own produce levels of racial diversity achieved by race‐based affirmative action. However, the two policies in combination, although likely expensive, may yield racial diversity comparable to race‐based affirmative action. Second, the use of affirmative action policies by some colleges reduces the diversity of similar‐quality colleges without such policies. Third, the combination of SES‐based affirmative action and race recruiting results in fewer academically‐overmatched Black and Hispanic students than under race‐based affirmative action, but the schools that use both also see a reduction in the academic achievement of enrolled students. 相似文献
210.
Which European Union actors are most powerful in the governance of the euro crisis? The euro crisis has reignited the classic debate between intergovernmentalists, who tend to stress the coercive power of dominant member states in the European Council, and supranationalists, who maintain that through the use of institutional power, the Commission, and the European Central Bank turned out the “winners” of the crisis. This article argues that euro crisis governance is best understood not just in terms of one form of power but instead as evolving through different constellations of coercive, institutional, and ideational power that favored different EU actors over the course of the crisis, from the initial fast‐burning phase (2010–2012), where the coercive and ideational power of Northern European member states in the European Council was strongest, to the slow‐burning phase (2012–2016), when greater influence was afforded supranational actors through the use of ideational and institutional power. 相似文献