全文获取类型
收费全文 | 70992篇 |
免费 | 3268篇 |
国内免费 | 5篇 |
专业分类
各国政治 | 4449篇 |
工人农民 | 2952篇 |
世界政治 | 6082篇 |
外交国际关系 | 3814篇 |
法律 | 34743篇 |
中国共产党 | 15篇 |
中国政治 | 777篇 |
政治理论 | 20484篇 |
综合类 | 949篇 |
出版年
2021年 | 411篇 |
2020年 | 1164篇 |
2019年 | 1523篇 |
2018年 | 1695篇 |
2017年 | 1990篇 |
2016年 | 2185篇 |
2015年 | 1824篇 |
2014年 | 2092篇 |
2013年 | 10496篇 |
2012年 | 1683篇 |
2011年 | 1839篇 |
2010年 | 1871篇 |
2009年 | 2093篇 |
2008年 | 1877篇 |
2007年 | 1882篇 |
2006年 | 2013篇 |
2005年 | 1907篇 |
2004年 | 1785篇 |
2003年 | 1625篇 |
2002年 | 1641篇 |
2001年 | 1776篇 |
2000年 | 1461篇 |
1999年 | 1314篇 |
1998年 | 1095篇 |
1997年 | 925篇 |
1996年 | 932篇 |
1995年 | 926篇 |
1994年 | 941篇 |
1993年 | 961篇 |
1992年 | 1045篇 |
1991年 | 1095篇 |
1990年 | 1034篇 |
1989年 | 1044篇 |
1988年 | 1061篇 |
1987年 | 1035篇 |
1986年 | 1042篇 |
1985年 | 1097篇 |
1984年 | 978篇 |
1983年 | 1019篇 |
1982年 | 902篇 |
1981年 | 866篇 |
1980年 | 668篇 |
1979年 | 713篇 |
1978年 | 612篇 |
1977年 | 544篇 |
1976年 | 498篇 |
1975年 | 447篇 |
1974年 | 462篇 |
1973年 | 448篇 |
1972年 | 392篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
This research demonstrates the value of laser scanning confocal microscopy (LSCM) as a research tool in osteological studies, and diagenetic studies in particular. LSCM combines properties of light and scanning electron microscopy using laser light to excite fluorophores throughout the z-axis, developing a 3-D image. Using differential staining and selecting for specific wavelengths of light, one can image targeted materials. This research is divided into two parts: visualizing bone structures such as proteins and their decompositional products and visualizing diagenesis. Part one of this study utilized pig bones as a means of testing the overall ability of LSCM to fluoresce bone. Twenty-three samples were imaged, including 13 samples from a decompositional study conducted 5 years previous, and 10 “fresh” samples collected from a commercial butcher. This part of the study determined that protein and organic components of the bone could be fluoresced and diagenetic alteration could be imaged. The second part of the study used human samples as a means of imaging and mapping diagenetic alterations. The second part of the study used 13 samples, including 4 clinical, 7 ancient, and 2 modern controls. The pig study used Basic Fuchsin and SlowFade Gold stains, while the human study used toluidine blue. Images were also taken with unstained elements. The results of the non-human study found that a fresh bone fluoresced differently than that of a 5-year subset, while the results of the human study confirmed these findings and determined that the bone diagenesis can be mapped using LSCM. 相似文献
2.
Journal of Quantitative Criminology - We tested the impact of juvenile arrest on asset accumulation, debt accumulation, and net worth from ages 20–30. We also examined whether indicators of... 相似文献
3.
Stephanie Hartley Allysha Powanda Winburn Itiel E. Dror 《Journal of forensic sciences》2022,67(1):68-79
Subjective decisions make human cognitive processes more susceptible to bias and error. Specifically, research indicates that additional context biases forensic anthropologists’ morphological analyses. To address whether metric analyses are also subject to bias, we conducted a pilot study in which 52 experienced osteologists measured a difficult-to-classify human femur, with or without additional contextual information. Using a metric sectioning-point sex-estimation method, participants provided a sex estimate for individual skeletal element(s) and, when given multiple elements, the combined skeletal assemblage. Control group participants (n = 24) measured only the femur. In addition to the femur, bias group participants (n = 28) either measured a female humerus and viewed a female-biasing photograph (n = 14) or measured a male humerus and viewed a male-biasing photograph (n = 14). We explored whether the experts in the different groups would differ in: (1) femoral measurements; (2) femoral sex-estimation conclusions; and (3) final sex-estimation conclusions for the skeletal assemblage. Although the femoral measurements and femoral sex estimates were comparable across groups, the overall sex estimates in the female-biased group were impacted by contextual information—differing from both the control and male-biased groups (p < 0.001). Our results demonstrate that cognitive bias can occur even in metric sex-estimation conclusions. Specifically, this occurred when the metric data and single-element sex estimates were synthesized into an overall estimate. Thus, our results suggest that metric methods are most vulnerable to bias when data are synthesized into an overall conclusion, highlighting the need for bias countermeasures and comprehensive statistical frameworks for synthesizing metric data to mitigate the effects of cognitive bias. 相似文献
4.
Walter E. Bruehs Nicole M. Tucker Kimberly A. Meline 《Journal of forensic sciences》2022,67(1):200-206
Often, criminal acts involving a vehicle are caught on digital video surveillance systems. While potentially useful for an investigation, the recording conditions are typically less than optimal for the extraction of key information for the identification of the perpetrator, such as a license plate. Providing the make, model and year of a questioned vehicle is a common request for examiners, to narrow the field of potential suspect vehicles. This study seeks to compare the performance of a nonpeer-reviewed make, model, and year determination between two separate groups, specifically, trained forensic image examiners and nontrained individuals. Results show that even with varied image capture conditions and quality, the trained forensic image examiners more correctly and completely identified the test group of questioned vehicles make, model, and year. 相似文献
5.
Janet L. Lauritsen 《犯罪学》2023,61(2):187-203
Criminology lacks sufficient data for many types of crime that are of great concern to society. This lack of data poses significant problems for determining whether resources are adequate for responding to these crimes or whether programmatic, legislative, or target-hardening efforts to prevent or reduce their occurrence are effective. Inadequate data about crime also produces a selective and incomplete narrative about crime that makes it easier for political and vested interests to exploit public concerns about crime for their own ends. In this address, I discuss what is needed to resolve these gaps and the ways in which criminologists can support a significant expansion of the crime data infrastructure. Such work is necessary to help ensure the future relevance of criminological research. 相似文献
6.
Reverse projection photogrammetry has long been used to estimate the height of an individual in forensic video examinations. A natural extrapolation would be to apply the same technique on a video to estimate the speed of an object by determining the distance traveled between two points over a set amount of time. To test this theory, five digital video recorders (DVRs) were connected to a single fixed camera to record a vehicle traveling down a track. The vehicle's speed was measured through Doppler radar by a trained operator and the speedometer of the vehicle was also recorded with a video camera. The recorded video was examined and the frames that best depict the beginning and end of the vehicles course were selected. Two reverse projection photogrammetric examinations were performed on the selected frames to establish the position of the vehicle. The distance between the two points was measured, and the time elapsed between the two points was examined. The outcome provided an accurate speed result with a standard degree of uncertainty. This study proves the feasibility of using video data and reverse projection photogrammetry to determine the speed of a vehicle with a limited set of variables. Further research is needed to determine how additional variables would impact the standard degree of uncertainty. 相似文献
7.
Professional baseball players are often thought of as making multi-million-dollar salaries, but most professional baseball players have recently made under $15,000 a year. Minor league players toiled under an onerous system resulting from baseball's judicially created antitrust exemption and lobbying efforts that exempted them from minimum wage and overtime. These factors allowed teams to impose a uniform player contract (UPC) on players with numerous unconscionable provisions for years. However, a late-night Tweet in August of 2022 sent shockwaves through the sports and labor world, announcing that the Major League Baseball Players Association (MLBPA) was sending out authorization cards to represent minor league players. After years of fighting to maintain the authority to impose conditions on minor league players, through lobbying and litigation, Major League Baseball (MLB) turned over a new leaf and recognized the unionization of minor league players under the MLBPA less than three weeks later. In light of this long sought-after recognition, this article takes a novel approach. First, it provides historical context for baseball's unique ability to impose working conditions on minor leaguers without significant concern for legal ramifications. Second, it provides an overview of the doctrine of contractual unconscionability and analyzes the prior UPC as an unconscionable agreement. Finally, it details the historic unionization process and makes detailed recommendations to ameliorate the unconscionable conditions minor league players have faced when they negotiate with MLB owners to draft their initial collective bargaining agreement. 相似文献
8.
Natur und Recht - Angesichts der enormen Zerschneidungswirkung von Bundesfernstraßen werden Grünbrücken in der Bundesrepublik vermehrt errichtet, sodass sich die Frage der... 相似文献
9.
10.
Criminal Law Forum - Fair labelling is an established principle of criminal justice that scrutinises the way that States use language in labelling criminal defendants and their conduct. I argue... 相似文献