全文获取类型
收费全文 | 1474篇 |
免费 | 84篇 |
专业分类
各国政治 | 113篇 |
工人农民 | 64篇 |
世界政治 | 141篇 |
外交国际关系 | 118篇 |
法律 | 768篇 |
中国政治 | 12篇 |
政治理论 | 330篇 |
综合类 | 12篇 |
出版年
2024年 | 3篇 |
2023年 | 20篇 |
2022年 | 21篇 |
2021年 | 26篇 |
2020年 | 47篇 |
2019年 | 65篇 |
2018年 | 65篇 |
2017年 | 73篇 |
2016年 | 78篇 |
2015年 | 51篇 |
2014年 | 67篇 |
2013年 | 225篇 |
2012年 | 72篇 |
2011年 | 48篇 |
2010年 | 43篇 |
2009年 | 50篇 |
2008年 | 59篇 |
2007年 | 70篇 |
2006年 | 48篇 |
2005年 | 56篇 |
2004年 | 42篇 |
2003年 | 39篇 |
2002年 | 46篇 |
2001年 | 23篇 |
2000年 | 20篇 |
1999年 | 24篇 |
1998年 | 14篇 |
1997年 | 9篇 |
1996年 | 9篇 |
1995年 | 15篇 |
1994年 | 9篇 |
1993年 | 4篇 |
1992年 | 20篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 10篇 |
1988年 | 8篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1969年 | 4篇 |
1966年 | 5篇 |
排序方式: 共有1558条查询结果,搜索用时 15 毫秒
91.
Previous research conducted into the use of the human ear in the field of forensic identification has focused upon the use of grids and manual methods to measure and catalogue the different anatomical features of the ear. To date, few have considered the importance of the presence of ear piercings and their possible role in human identification. This study aims to highlight the common distribution of piercings of both ears in both genders and to explore the effect of piercings on earprints. The presence of a piercing may, in part, help to explain why partial and not whole earprints are sometimes recovered from a scene of crime (suggesting that the offender's ears may be pierced). The presence of piercings through the tragus and the superior part of the helix are shown to be infrequent and thus may be used to assist the identification of a body, due to its relative rarity with respect to piercings found in other areas of the ear. 相似文献
92.
93.
94.
Salas A Prieto L Montesino M Albarrán C Arroyo E Paredes-Herrera MR Di Lonardo AM Doutremepuich C Fernández-Fernández I de la Vega AG Alves C López CM López-Soto M Lorente JA Picornell A Espinheira RM Hernández A Palacio AM Espinoza M Yunis JJ Pérez-Lezaun A Pestano JJ Carril JC Corach D Vide MC Alvarez-Iglesias V Pinheiro MF Whittle MR Brehm A Gómez J 《Forensic science international》2005,150(2-3):191-198
A qualitative and quantitative analytical method was developed and validated for the determination of 49 licit and illicit drugs in oral fluid. Small oral fluid samples, volume 1mL, were collected from volunteers using a modified Omni-Sal device and the analytes were extracted from an oral fluid/buffer mixture using a single Bond Elut Certify solid phase extraction cartridge. Liquid chromatography-tandem mass spectrometry (LC-MS-MS) and gas chromatography-repetitive full scan mass spectrometry (GC-MS) were used in parallel to analyze the extracts for the targeted drugs. Extracts were analyzed by GC-MS in their underivatized form and as their pentafluoropropionyl derivatives. Deuterated internal standards were used for quantification of drugs of abuse by LC-MS-MS to minimize matrix effects. Methadone-d(9) and tumoxetine were used as the internal standards for quantification of non-derivatized and derivatized analytes respectively by GC-MS. Linearity was demonstrated over the range 5-200 ng/mL and limits of detection were less than 4 ng/mL for each drug analyzed. The method demonstrated acceptable recoveries for most of the analytes and good intra- and inter-day precision. Acquisition of data by repetitive full scan GC-MS allows the addition of further analytes to the target menu. 相似文献
95.
96.
An HPLC-APCI-MS(/MS) method for the (trace) analysis of the most commonly encountered peroxide explosives, hexamethylenetriperoxidediamine (HMTD) and triacetonetriperoxide (TATP), has been developed. With this method, HMTD and TATP have been analyzed in the same run. (Pseudo-)molecular ions of these peroxides have been obtained as base peak under the same condition. A series of product ions was produced from these pseudo-molecular ions ([HMTD - 1]+ and [TATP + NH4]+) in the MS/MS analysis. We also pioneered in showing that a TATP molecular ion [TATP + H]+ can be observed with HPLC-MS/MS. The limit of detection for HMTD and TATP was 0.26 and 3.3 ng, respectively, on column by HPLC-MS in the Full Scan mode and 0.08 and 0.8, respectively, by HPLC-APCI-MS/MS in Selected Reaction Monitoring (single mass unit) mode. The method presented has been applied successfully for the identification of peroxides in the bulk solid state (powder sample), as well as in post-blast extracts originating from a forensic case. For the post-blast extracts, the use of tandem MS has been shown clearly to be of crucial importance for the identification and detection of the peroxide explosives. 相似文献
97.
98.
Góes AC da Silva DA Fonseca Gil EH da Silva MT Pereira RW de Carvalho EF 《Forensic science international》2004,140(1):131-132
Allele frequencies for 16 short tandem repeats (STR) loci were determined with a sample of 230-300 unrelated individuals from the population of Rio de Janeiro, Brazil. The loci are the most commonly used in forensic and paternity testing, being analysed by the Identifiler (Applied Biosystems) and PowerPlex 2.1 (Promega) commercial kits. It was proved that Penta E and D18S51 are the most polymorphic loci. 相似文献
99.
Sarina Saragossi Bruno van Pottelsberghe de la Potterie 《The Journal of Technology Transfer》2003,28(1):47-51
In recent years, there has been a surge in patenting by Belgian universities. It appears that this increase can be attributed to growth of biotechnology, where there is a greater propensity to patent, to a desire on the part of universities to enhance commercialization through technology transfer offices (TTOs), and to effective collaboration between universities and government-sponsored research centers. Our qualitative analysis reveals that patent statistics could be a misleading indicator of an individual university's technological productivity, since many inventions are developed at universities, yet applied by other institutions. 相似文献
100.