全文获取类型
收费全文 | 5246篇 |
免费 | 166篇 |
专业分类
各国政治 | 185篇 |
工人农民 | 248篇 |
世界政治 | 372篇 |
外交国际关系 | 190篇 |
法律 | 3357篇 |
中国政治 | 40篇 |
政治理论 | 994篇 |
综合类 | 26篇 |
出版年
2023年 | 39篇 |
2021年 | 31篇 |
2020年 | 62篇 |
2019年 | 89篇 |
2018年 | 112篇 |
2017年 | 109篇 |
2016年 | 129篇 |
2015年 | 77篇 |
2014年 | 106篇 |
2013年 | 508篇 |
2012年 | 128篇 |
2011年 | 155篇 |
2010年 | 104篇 |
2009年 | 128篇 |
2008年 | 134篇 |
2007年 | 131篇 |
2006年 | 145篇 |
2005年 | 101篇 |
2004年 | 116篇 |
2003年 | 123篇 |
2002年 | 99篇 |
2001年 | 223篇 |
2000年 | 220篇 |
1999年 | 160篇 |
1998年 | 68篇 |
1997年 | 71篇 |
1996年 | 63篇 |
1995年 | 61篇 |
1994年 | 68篇 |
1993年 | 64篇 |
1992年 | 118篇 |
1991年 | 110篇 |
1990年 | 135篇 |
1989年 | 125篇 |
1988年 | 141篇 |
1987年 | 134篇 |
1986年 | 111篇 |
1985年 | 113篇 |
1984年 | 90篇 |
1983年 | 74篇 |
1982年 | 58篇 |
1981年 | 52篇 |
1980年 | 41篇 |
1979年 | 57篇 |
1978年 | 40篇 |
1976年 | 35篇 |
1975年 | 31篇 |
1974年 | 41篇 |
1973年 | 28篇 |
1970年 | 27篇 |
排序方式: 共有5412条查询结果,搜索用时 812 毫秒
881.
AbstractIt is now accepted that to have an understanding of housing affordability one must consider not only housing costs, but also the transportation costs associated with that household location. To make this information readily accessible to the public, the United States government created an Internet resource, the Location Affordability Portal – Version 2 (www.locationaffordability.info), to provide housing and transportation costs for every neighborhood in all 50 states and the District of Columbia. Although the statistical model at the heart of this resource was designed for predictive accuracy, its design and parameter estimates can provide additional insights into the interaction of housing cost and transportation choices (and thus its cost). This study describes the development and explores the policy implications (and limitations) of this structural equations model, the Location Affordability Index Model – Version 2 (LAIM2). 相似文献
882.
883.
Louisa J. Baillie B.H.Sc. B.F.A. Jillian C. Muirhead D.M.I.T. Phil Blyth B.H.B. M.B.Ch.B. Ph.D. Brian E. Niven B.Sc. M.Sc. George J. Dias B.B.S. M.S. Ph.D. 《Journal of forensic sciences》2016,61(Z1):S60-S70
The head is positioned erect for an approximation; yet most facial soft tissue depths (FSTD) used are measured from supine subjects. Depth difference might be significant, but there is a paucity of data to verify. This study compared erect and supine values for 17 landmarks from 30 healthy New Zealand (European population affinity) women (18–30 or 40–55 years) in erect then supine positions. Height, weight, and sonographic FSTD data, totaling 1020 measurements, were obtained. Three midline and seven averaged bilateral values were compared using ANOVA, p values, and Pearson's correlations. Correlative strength of age and body mass index, BMI (kg/m2), was determined by values. Results showed averaged erect and supine differences were significant for four of ten FSTDs. Between individuals, difference was various and not unidirectional. In conclusion, depth differences were observed but not all significant or unidirectional, BMI significantly influenced nine FSTD values, but age group did not. 相似文献
884.
Dane T. Plaza B.S. Jamia L. Mealy M.F.S. J. Nicholas Lane M.S.F.S. M. Neal Parsons M.S. Abigail S. Bathrick M.F.S. Donia P. Slack M.S. 《Journal of forensic sciences》2016,61(2):485-488
In forensic science, biological material is typically collected from evidence via wet/dry double swabbing with cotton swabs, which is effective but can visibly damage an item's surface. When an item's appearance must be maintained, dry swabbing and tape‐lifting may be employed as collection techniques that are visually nondestructive to substrates' surfaces. This study examined the efficacy of alternative swab matrices and adhesive lifters when collecting blood and fingerprints from glass, painted drywall, 100% cotton, and copy paper. Data were evaluated by determining the percent profile and quality score for each STR profile generated. Hydraflock® swabs, BVDA Gellifters®, and Scenesafe FAST? tape performed as well as or better than cotton swabs when collecting fingerprints from painted drywall and 100% cotton. Collection success was also dependent on the type of biological material sampled and the substrate on which it was deposited. These results demonstrated that alternative swabs and adhesive lifters can be effective for nondestructive DNA collection from various substrates. 相似文献
885.
Erwin J. A. T. Mattijssen M.Sc. Ivo Alberink Ph.D. Suzanne D. Brouwer M.Sc. Wim Kerkhoff 《Journal of forensic sciences》2016,61(3):765-772
When a bullet ricochets from wood, various parameters will influence its behavior. In this study, the influence of the wood grain on the ricochet angle (β) and deflection angle (γ) is assessed. Series of five .32 Auto bullets were fired at different angles of incidence (α) on boards of six wood types. The results confirm the previously shown effect that the mean β‐angles usually exceed α and increase when α increases. Overall, the maximum mean γ occurs when the angle of wood grain (ζ), in relation to the plane of impact, lies between 30° and 75° but differs per combination of wood and α. The results show the inclination of γ toward the left or right, depending on the bullets left or right rotation while also showing that the direction of ζ can enhance or counteract this effect considerably, especially when α is close to the critical ricochet angle. 相似文献
886.
Burned skeletal material is often very fragile and at high risk for fragmentation during packaging and transportation. One method that has been suggested to protect bones in these cases is to carefully wrap them in aluminum foil. Traces of aluminum, however, are known to transfer from foil packaging materials to food products. If such transfer occurs between aluminum foil and bones, it could interfere with subsequent chemical, elemental and isotopic analyses, which are becoming more common in forensic anthropological investigations. This study examined aluminum levels in bones prior to and following the use of aluminum foil packaging and storage for a 6‐week period. Results indicate no significant change in the detected levels of aluminum (p > 0.05), even when packaged in compromised foil and exposed to elevated temperatures. Aluminum foil can therefore continue to be recommended as a packaging medium without affecting subsequent chemical examinations. 相似文献
887.
Taphonomic Patterning of Cemetery Remains Received at the Office of the Chief Medical Examiner,Boston, Massachusetts
下载免费PDF全文
![点击此处可从《Journal of forensic sciences》网站下载免费的PDF全文](/ch/ext_images/free.gif)
James T. Pokines Ph.D. Debra Prince Zinni Ph.D. Kate Crowley D.M.D. 《Journal of forensic sciences》2016,61(Z1):S71-S81
A sample of 49 cases of cemetery remains received at the Office of the Chief Medical Examiner, Massachusetts (OCME‐MA), in Boston was compared with published taphonomic profiles of cemetery remains. The present sample is composed of a cross section of typical cases in this region that ultimately are derived from modern to historical coffin burials and get turned over to or seized by law enforcement. The present sample was composed of a large portion of isolated remains, and most were completely skeletonized. The most prevalent taphonomic characteristics included uniform staining (77.6%), coffin wear (46.9%), and cortical Exfoliation (49.0%). Other taphonomic changes occurring due to later surface exposure of cemetery remains included subaerial weathering, animal gnawing, algae formation, and excavation marks. A case of one set of skeletal remains associated with coffin artifacts and cemetery offerings that was recovered from transported cemetery fill is also presented. 相似文献
888.
Suicide by shotgun is a common method of suicide with high regional variation. We sought to describe their distinct, challenging features and provide demographic and risk characteristics. We reviewed 228 gunshot wounds autopsied at Mayo Clinic from 1994 to 2014; of these, 75 (32.9%) were shotgun wounds. All were suicides and contact range. Ages ranged from 14 to 92 years old; of these, 97% were men. The majority involved the head (70.9%), were intraoral (48.2%), and had upward (73.2%) and backward (73.2%) directionality. Next most common was the chest (21.5%), with backward (94.1%) and downward (64.7%) directionality. Four involved multiple wounds. Wadding was recovered in 16 (21.3%) cases. Six (8.0%) had a survival period. Most (66.7%) took place at home. Seventy‐one percent had a known psychiatric history; 32.4% had positive toxicology. Although contact range shotgun wounds cause severe destruction, entrance wound and other characteristic are identifiable with thorough scene, autopsy, and radiographic documentation. 相似文献
889.
Joseph T. Hefner Ph.D. Brian F. Spatola M.A. Nicholas V. Passalacqua Ph.D. Timothy P. Gocha Ph.D. 《Journal of forensic sciences》2016,61(6):1440-1449
Anatomical crania are occasionally encountered in forensic anthropology laboratories when that material is mistaken for forensically significant human remains. Using craniometric analyses and statistical measures of sample homogeneity, we determine whether anatomical material can be described as a single, homogenous group or as a diverse mix of populations. Twenty‐one interlandmark distances were collected from 85 anatomical preparations. Distance measures were calculated between all pairs using a pooled within‐sample variance/covariance matrix and then subjected to a Defrise‐Gussenhoven test between each paired distance to test whether each pair was drawn randomly from the same population. In the Defrise‐Gussenhoven analysis, twenty‐two percent (n = 66) of the 300 pairwise combinations were significant at the 0.05 level or below. The level of homogeneity suggests a majority of that material originated from the subcontinent of India or West Asia. Therefore, anatomical material can be viewed as a moderately homogenous group, but with a shared taphonomic history. 相似文献
890.
Erwin J. A. T. Mattijssen M.Sc. K. Dieter H. Pater M.Sc. Reinoud D. Stoel Ph.D. 《Journal of forensic sciences》2016,61(6):1456-1460
For shooting scene reconstruction purposes, knowledge about the ricochet behavior of bullets provides valuable information. In this study, the critical ricochet angles of four cartridge types were established on plain float glass. The estimates of the critical ricochet angles varied between cartridge types and were 21.0° for .32 Auto FMJ bullets, 15.8° for 9 mm Luger FMJ bullets, 17.6° for .45 Auto FMJ bullets, and 21.3° for 9 mm Luger, Action NP bullets. The corresponding ricochet and deflection angles per incidence angle varied depending on the state of the ricocheted bullets. The mean ricochet angles are always lower than the corresponding angles of incidence, and the mean ricochet angles for the FMJ bullets with undamaged jackets are lower than those of bullets where the jacket is either damaged or the bullet partially ricocheted and partially perforated. Mean ricochet angles are lower for undamaged FMJ bullets than for undamaged Action NP bullets. 相似文献