全文获取类型
收费全文 | 1290篇 |
免费 | 52篇 |
专业分类
各国政治 | 45篇 |
工人农民 | 257篇 |
世界政治 | 98篇 |
外交国际关系 | 77篇 |
法律 | 586篇 |
中国政治 | 20篇 |
政治理论 | 249篇 |
综合类 | 10篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 6篇 |
2020年 | 24篇 |
2019年 | 30篇 |
2018年 | 47篇 |
2017年 | 46篇 |
2016年 | 37篇 |
2015年 | 42篇 |
2014年 | 36篇 |
2013年 | 175篇 |
2012年 | 31篇 |
2011年 | 39篇 |
2010年 | 33篇 |
2009年 | 42篇 |
2008年 | 45篇 |
2007年 | 49篇 |
2006年 | 41篇 |
2005年 | 48篇 |
2004年 | 62篇 |
2003年 | 42篇 |
2002年 | 44篇 |
2001年 | 23篇 |
2000年 | 25篇 |
1999年 | 17篇 |
1998年 | 13篇 |
1997年 | 28篇 |
1996年 | 33篇 |
1995年 | 16篇 |
1994年 | 25篇 |
1993年 | 20篇 |
1992年 | 28篇 |
1991年 | 23篇 |
1990年 | 18篇 |
1989年 | 14篇 |
1988年 | 13篇 |
1987年 | 8篇 |
1986年 | 15篇 |
1985年 | 12篇 |
1984年 | 9篇 |
1983年 | 11篇 |
1982年 | 11篇 |
1981年 | 11篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 4篇 |
排序方式: 共有1342条查询结果,搜索用时 15 毫秒
941.
Application of the BioMek 2000 Laboratory Automation Workstation and the DNA IQ System to the extraction of forensic casework samples 总被引:1,自引:0,他引:1
Greenspoon SA Ban JD Sykes K Ballard EJ Edler SS Baisden M Covington BL 《Journal of forensic sciences》2004,49(1):29-39
Robotic systems are commonly utilized for the extraction of database samples. However, the application of robotic extraction to forensic casework samples is a more daunting task. Such a system must be versatile enough to accommodate a wide range of samples that may contain greatly varying amounts of DNA, but it must also pose no more risk of contamination than the manual DNA extraction methods. This study demonstrates that the BioMek 2000 Laboratory Automation Workstation, used in combination with the DNA IQ System, is versatile enough to accommodate the wide range of samples typically encountered by a crime laboratory. The use of a silica coated paramagnetic resin, as with the DNA IQ System, facilitates the adaptation of an open well, hands off, robotic system to the extraction of casework samples since no filtration or centrifugation steps are needed. Moreover, the DNA remains tightly coupled to the silica coated paramagnetic resin for the entire process until the elution step. A short pre-extraction incubation step is necessary prior to loading samples onto the robot and it is at this step that most modifications are made to accommodate the different sample types and substrates commonly encountered with forensic evidentiary samples. Sexual assault (mixed stain) samples, cigarette butts, blood stains, buccal swabs, and various tissue samples were successfully extracted with the BioMek 2000 Laboratory Automation Workstation and the DNA IQ System, with no evidence of contamination throughout the extensive validation studies reported here. 相似文献
942.
Greenspoon SA Ban JD Pablo L Crouse CA Kist FG Tomsey CS Glessner AL Mihalacki LR Long TM Heidebrecht BJ Braunstein CA Freeman DA Soberalski C Nathan B Amin AS Douglas EK Schumm JW 《Journal of forensic sciences》2004,49(1):71-80
The PowerPlex 16 BIO multiplex short tandem repeat (STR) system contains the 13 CODIS loci (FGA, TPOX, D8S1179, vWA, D18S51, D21S11, TH01, D3S1358, CSF1PO, D16S539, D7S820, D13S317, and DS5S818), plus two pentanucleotide repeat loci (Penta D and Penta E) and the sex-identifying locus. Amelogenin. The PowerPlex 16 BIO System is optimized for use with the Hitachi FMBIO gel imaging systems. A consortium of seven independent laboratories collaborated to perform the studies defined by the FBI standards for performing a developmental validation, including the evaluation of sample concordance, percent stutter determination, nonprobative casework, precision, sensitivity, mixture determination, effect of substrates, the impact of environmental insults, and species specificity. All samples tested for concordance were consistent except for one sample from the Virginia Division of Forensic Science database that displayed discordance at D13S317, a locus whose primer sequence was altered. Stutter values were comparable to those of other STR multiplex systems, the precision was comparable to other multiplexes analyzed by gel electrophoresis, the DNA profiles were unchanged by the substrate upon which the blood samples were placed, and the nonprobative casework samples re-typed for the PowerPlex 16 BIO System were consistent with previous typing results. When greater than 0.125 ng of DNA was placed into the PowerPlex 16 BIO System amplification reaction, a full profile was generated by all laboratories. The mixture study results were comparable to those reported for other multiplex systems, the environmental study demonstrated a loss of larger molecular weight loci when samples were incubated at elevated temperatures for a prolonged period of time, and the only notable cross species hybridization was observed with primate DNA samples. This extensive validation work performed demonstrates that the PowerPlex 16 BIO System provides STR data of a quality comparable with other PowerPlex STR multiplex kits as well as other widely used STR multiplexes and is thus suitable for evidentiary casework analysis as well as database sample profiling. 相似文献
943.
944.
Susan M. Johnson 《Journal of youth and adolescence》1981,10(3):221-232
There is a continuous recognition in the literature of residential treatment of the need for studies to assess the impact of key variables which constitute a residential milieu on the treatment environment and, by implication, on the treatment outcome. One key variable is staff cohesion. The present study explored the effect of varying levels of staff cohesion on the treatment environment in a residential treatment center for disturbed adolescents. The results suggest that the variables Support, Personal Problem Orientation, Autonomy, Practical Orientation, and Staff Control are significantly affected by varying levels of staff cohesion. However, the clients' perception of their environment did not appear to be influenced by staff cohesion level.Received M.A. from University of British Columbia, B.C., Canada. Current interests are process of psychotherapy, interpersonal conflict resolution. 相似文献
945.
The Y-chromosomal binary marker P25 is a paralogous sequence variant, rather than a SNP: three copies of the P25 sequence lie within the giant palindromic repeats on Yq, and one copy has undergone a C to A transversion to define haplogroup R1b (designated C/C/A). Since gene conversion is known to be active in the palindromic repeats, we reasoned that P25 might be liable to back-mutation by gene conversion, yielding the ancestral state C/C/C. Through analysis of a set of binary markers in Y-chromosomes in two large samples from Great Britain and the Iberian Peninsula we show that such conversion events have occurred at least twice, and provide preliminary evidence that the reverse conversion event (yielding C/A/A) has also occurred. Because of its inherent instability, we suggest that P25 be used with caution in forensic studies, and perhaps replaced with the more reliable binary marker M269. 相似文献
946.
947.
948.
949.
950.