全文获取类型
收费全文 | 2512篇 |
免费 | 29篇 |
专业分类
各国政治 | 274篇 |
工人农民 | 41篇 |
世界政治 | 113篇 |
外交国际关系 | 118篇 |
法律 | 1637篇 |
中国共产党 | 7篇 |
中国政治 | 15篇 |
政治理论 | 325篇 |
综合类 | 11篇 |
出版年
2024年 | 10篇 |
2023年 | 12篇 |
2022年 | 13篇 |
2021年 | 22篇 |
2020年 | 43篇 |
2019年 | 48篇 |
2018年 | 117篇 |
2017年 | 102篇 |
2016年 | 121篇 |
2015年 | 96篇 |
2014年 | 66篇 |
2013年 | 192篇 |
2012年 | 80篇 |
2011年 | 75篇 |
2010年 | 70篇 |
2009年 | 91篇 |
2008年 | 122篇 |
2007年 | 156篇 |
2006年 | 153篇 |
2005年 | 88篇 |
2004年 | 76篇 |
2003年 | 69篇 |
2002年 | 78篇 |
2001年 | 78篇 |
2000年 | 69篇 |
1999年 | 47篇 |
1998年 | 18篇 |
1997年 | 21篇 |
1996年 | 11篇 |
1995年 | 12篇 |
1994年 | 12篇 |
1992年 | 14篇 |
1991年 | 21篇 |
1990年 | 24篇 |
1989年 | 29篇 |
1988年 | 26篇 |
1987年 | 19篇 |
1986年 | 25篇 |
1985年 | 29篇 |
1984年 | 17篇 |
1983年 | 14篇 |
1982年 | 6篇 |
1981年 | 27篇 |
1979年 | 17篇 |
1978年 | 12篇 |
1977年 | 10篇 |
1975年 | 12篇 |
1974年 | 14篇 |
1973年 | 14篇 |
1971年 | 5篇 |
排序方式: 共有2541条查询结果,搜索用时 0 毫秒
51.
Two main approaches can be used for determining the age of an ink: indirect dating and direct dating. Indirect dating is based on the chemical analysis of an ink followed by comparison with known samples in a reference collection. The collection should contain information about the inks including the market introduction dates. This approach may allow for an anachronism to be detected. The second concept is based on measuring ink components that change with age. The analysis of solvents in ballpoint inks may be a useful parameter for determining the age of ink on paper. In a previous study, the authors demonstrated that thermal desorption of ink directly from paper, followed by chemical analysis using gas chromatography-mass spectrometry (GC-MS), is a promising procedure for characterizing ink-binder resins and solvents. Preliminary tests showed that monitoring the evaporation of ink solvent from ink on paper is not a suitable method for ink dating. Thermal analysis of ink on paper in two steps revealed that fresh ink releases a relative amount of solvent at a certain low temperature in a defined period of time, which decreases as the ink ages. As a consequence, this relative amount of solvent released at a certain low temperature, and its decrease with time, can be used to estimate ink age. This age-dependent parameter was studied in 85 different inks ranging in age from 1 week to 1.5 years. It was found that some inks showed a significant decrease of this parameter up to an age of several months, and that the aging process can be monitored within this period. For other inks, however, the age-dependent parameter decreases relatively fast, e.g., within a few days, to a constant level, which can be too fast for casework. Based on these results, a general procedure for assessing the age of ballpoint pen inks on paper was developed. 相似文献
52.
Y-STR polymorphism in Central Anatolian Region of Turkey 总被引:2,自引:0,他引:2
Rustamov A Gümüş G Karabulut HG Elhan AH Kadikiran A Bökesoy I 《Forensic science international》2004,139(2-3):227-230
Eight Y-chromosome specific STR (Y-STR) loci including DYS19, DYS388, DYS389I, DYS389II, DYS390, DYS391, DYS392 and DYS393 were investigated in a group of males from Central Anatolian Region of Turkey. Healthy 59 males living in this region for at least three generations were included in the study. PCR analysis was carried out with Y-STR specific primers on genomic DNA obtained from peripheral blood samples and size determination of PCR products was performed by silver staining following 6% polyacrylamide gel electrophoresis (PAGE). DYS388 was found to be the locus with lowest diversity (D) whereas DYS389II was the locus with highest diversity. The current study presented a framework of variation for the eight Y-STR loci in Central Anatolian population. 相似文献
53.
54.
Colour marking cartridges as the FX ammunition (Simunition Europe, Brussels) are increasingly used by the police for realistic close range combat training. Conversion kits for service weapons of different manufacturers are available. The ballistic data of this ammunition is reported and experimentally verified. The risk of injury seems to be very low, if the recommended protective equipment is used. Small hematomas up to superficial lacerations are to be expected only in areas over a bony support. Shots to the unprotected eye will result in severe injuries. 相似文献
55.
M. Nastainczyk S. Schulz M. Kleiber U.D. Immel 《Forensic Science International: Genetics Supplement Series》2009,2(1):53-54
Analysis of short tandem repeat (STR) markers currently represents the most useful instrument in the field of forensic genetics. The problem with forensic material is the degradation of the sample material. In recent years, several papers have demonstrated that short amplicon STR (miniSTR) represents one of the most useful tools for analyzing degraded DNA samples.In the present study, we attempted to develop a short amplicon STR multiplex system (autosomal and y-chromosomal) for analyzing degraded DNA using some newly designed primer sets for a multiplex polymerase chain reaction (PCR) systems for typing.An assay of degraded DNA samples using the designed multiplex systems, including artificially degraded samples and degraded forensic casework samples, proved remarkably effective. Comparing the multiplex with commercial kits, first results show a well success rate. 相似文献
56.
Christoph U. Schmid Reinhard Moos Ulrich Torggler Karl Weber 《Juristische Bl?tter》2009,131(6):400-404
57.
Zusammenfassung Die europarechtlichen Normen des sog. individuenbezogenen Artenschutzes (insbesondere Art. 5 lit.
a Vogelschutz- und Art. 12 Abs. 1 lit. a FFH-Richtlinie) sowie die innerstaatlichen Umsetzungsnormen
in § 42 Abs. 1 BNatSchG sind entgegen einer weit verbreiteten Tendenz als Verbote bestimmter gezielt
auf individuelle Exemplare der geschützten Arten gerichtete Zugriffshandlungen ernst zu nehmen. Der
Beitrag zeigt auf, wie auf dieser Basis der ausufernden Anwendung der genannten Normen vorgebaut werden
kann. Die abgestufte Handlungsverantwortlichkeit von Verkehrsteilnehmern, Beh?rden zur ordnungsbeh?rdlichen
Regelung des Verkehrsgeschehens sowie zur Zulassung von Verkehrsanlagen und -wegen wird verdeutlicht, zugleich
ein praktikabler Weg zum ma?vollen und differenzierten Umgang mit dem besonderen Artenschutzrecht aufgezeigt. 相似文献
58.
59.
In a report released on 28 January 2004, the Canadian Human Rights Commission recommended that the Correctional Service of Canada (CSC) implement a pilot needle exchange program in three or more correctional facilities, at least one of them a women's facility, by June 2004. 相似文献
60.