全文获取类型
收费全文 | 366篇 |
免费 | 14篇 |
专业分类
各国政治 | 15篇 |
工人农民 | 12篇 |
世界政治 | 34篇 |
外交国际关系 | 23篇 |
法律 | 168篇 |
中国政治 | 1篇 |
政治理论 | 120篇 |
综合类 | 7篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 14篇 |
2017年 | 11篇 |
2016年 | 10篇 |
2015年 | 7篇 |
2014年 | 10篇 |
2013年 | 67篇 |
2012年 | 6篇 |
2011年 | 4篇 |
2010年 | 11篇 |
2009年 | 7篇 |
2008年 | 8篇 |
2007年 | 11篇 |
2006年 | 15篇 |
2005年 | 9篇 |
2004年 | 13篇 |
2003年 | 9篇 |
2002年 | 16篇 |
2001年 | 6篇 |
2000年 | 3篇 |
1999年 | 5篇 |
1998年 | 6篇 |
1997年 | 9篇 |
1996年 | 10篇 |
1995年 | 2篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 7篇 |
1990年 | 4篇 |
1989年 | 6篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1978年 | 6篇 |
1976年 | 2篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1970年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有380条查询结果,搜索用时 15 毫秒
251.
252.
Conflict and rent-seeking success functions: Ratio vs. difference models of relative success 总被引:1,自引:0,他引:1
Jack Hirshleifer 《Public Choice》1989,63(2):101-112
The rent-seeking competitions studied by economists fall within a much broader category of conflict interactions that also includes military combats, election campaigns, industrial disputes, lawsuits, and sibling rivalries. In the rent-seeking literature, each party's success pi (which can be interpreted either as the probability of victory or as the proportion of the prize won) has usually been taken to be a function of the ratio of the respective resource commitments. Alternatively, however, pi may instead be a function of the difference between the parties' commitments to the contest. The Contest Success Function (CSF) for the difference from is a logistic curve in which, as is consistent with military experience, increasing returns apply up to an inflection point at equal resource commitments. A crucial flaw of the traditional ratio model is that neither onesided submission nor two-sided peace between the parties can ever occur as a Cournot equilibrium. In contrast, both of these outcomes are entirely consistent with a model in which success is a function of the difference between the parties' resource commitments.In preparing successive drafts of this paper I have benefited from suggestions and comments from Michele Boldrin, Avinash Dixit, Arye L. Hillman, David Hirshleifer, Eric S. Maskin, David Levine, Eric Rasmusen, John G. Riley, Russell Roberts, and Leo K. Simon. 相似文献
253.
A bullet signature measurement system based on a stylus instrument was developed at the National Institute of Standards and Technology (NIST) for the signature measurements of NIST RM (Reference Material) 8240 standard bullets. The standard bullets are developed as a reference standard for bullet signature measurements and are aimed to support the recently established National Integrated Ballistics Information Network (NIBIN) by the Bureau of Alcohol, Tobacco and Firearms (ATF) and the Federal Bureau of Investigation (FBI). The RM bullets are designed as both a virtual and a physical bullet signature standard. The virtual standard is a set of six digitized bullet signatures originally profiled from six master bullets fired at ATF and FBI using six different guns. By using the virtual signature standard to control the tool path on a numerically controlled diamond turning machine at NIST, 40 RM bullets were produced. In this paper, a comparison parameter and an algorithm using auto-and cross-correlation functions are described for qualifying the bullet signature differences between the RM bullets and the virtual bullet signature standard. When two compared signatures are exactly the same (point by point), their cross-correlation function (CCF) value will be equal to 100%. The measurement system setup, measurement program, and initial measurement results are discussed. Initial measurement results for the 40 standard bullets, each measured at six land impressions, show that the CCF values for the 240 signature measurements are higher than 95%, with most of them even higher than 99%. These results demonstrate the high reproducibility for both the manufacturing process and the measurement system for the NIST RM 8240 standard bullets. 相似文献
254.
A Scientific Working Group on DNA Analysis Methods (SWGDAM) developmental validation study was carried out on two Y-STR multiplex systems (MPI and MPII) that collectively permit the co-amplification of 19 Y-STR markers, including DYS393, DYS392, DYS391, DYS389I, DYS389II, Y-GATA-A7.2 (DYS461), DYS438, DYS385a and DYS385b (MPI); DYS425, DYS388, DYS390, DYS439, DYS434, DYS437, Y-GATA-C.4, Y-GATA-A7.1 (DYS460), Y-GATA-H.4, and DYS 19 (MPII). Performance checks subsequent to PCR parameter optimization indicated that MPI and MPII were suitably reproducible, precise and accurate for forensic use. The sensitivity of the systems was such that a full 19-locus Y-STR profile was obtainable with 150-200 pg of male DNA, and some loci were detectable even with as little as 20-30 pg of input DNA. Primate specificity was demonstrated by the lack of cross-reactivity with a variety of commonly encountered bacterial and animal species, with the single exception of a monomorphic canine product that was outside of the size range of human alleles from any of the 19 loci. Not surprisingly, cross-reactivity was observed with a number of male and female nonhuman primates. Environmentally compromised samples produced full or partial Y-STR profiles. For example, a semen stain exposed to the outdoor elements for six months still gave a 13-locus Y-STR profile. Although a limited number of female DNA artifacts were observed in mixed stains in which the male DNA comprised 1/300 of the total, the full 19-locus male profile was easily discernible. Even at a 1500-to-2000-fold dilution of male DNA with female DNA partial Y-STR profiles were obtained. Furthermore, the potential utility of MPI and MPII for forensic casework is exemplified by their ability to dissect out the male haplotype in a variety of case-type samples, including, inter alia, post-coital vaginal swabs, admixed male and female bloodstains, the nonsperm fraction from a differentially extracted semen stain, and determination of the number of male donors in mixed semen stains. 相似文献
255.
Short tandem repeat (STR) analysis is a valuable tool in identifying the source of biological stains, particularly from the investigation of sexual assault crimes. Difficulties in analysis arise primarily in the interpretation of mixed genotypes when cell separation of the sexual assailant's sperm from the victim's cells is incomplete. The forensic community continues to seek improvements in cell separation methods from mixtures for DNA typing. The feasibility of applying laser microdissection (LMD) technology to precisely separate sexual assault cell mixtures by visual inspection coupled with laser dissection was assessed through three experiments. First, various histological stains were evaluated for use with LMD and DNA analysis. Second, different DNA isolation methods were evaluated on LMD-collected cells. Finally, STR analysis was performed on LMD-separated sperm cells from mixtures of semen and female buccal epithelial cells. The results indicated (a) hematoxylin/eosin staining performed best in its ability to differentiate sperm and epithelial cells while exhibiting the least negative effect on further downstream analysis; (b) both QIAamp and Lyse-N-Go methods were useful for recovery of DNA from LMD-collected sperm cells; and (c) LMD separation provided clear STR profiles of the male donor with the absence of any additional alleles from the female donor. This report describes an efficient, low-manipulation LMD method for the efficient separation of spermatozoa from two-donor sperm/epithelial cell mixtures. 相似文献
256.
257.
The following is a study conducted to determine whether there was any significant difference in carboxyhemoglobin (COHb) saturation levels between the heart blood and blood collected from a peripheral site. The average heart blood to peripheral blood COHb saturation level ratio in the 42 cases studied was 1.09. Sixty-two percent (26 of 42) of the cases had a heart blood to peripheral blood ratio between 0.9 and 1.1; 74% (31 of 42) had a ratio between 0.8 and 1.2. Eighty-three percent (35 of 42) had a ratio between 0.7 and 1.3. There were four cases where the heart blood to peripheral blood ratio was either below 0.6 or greater than 1.4. The differences between the two sites were not statistically significant. 相似文献
258.
Since its inception in 1930, the Administration of Justice Department at San Jose State University has undergone numerous changes. This article develops a curriculum orientation matrix to analyze those changes. The results of the application of the matrix indicate movement from a law enforcement, training emphasis to the present system-oriented, professional-social science mix. 相似文献
259.
260.
Mr. Robert A. Hutchinson Mr. Jack L. Eisenhauer Mr. Gerald J. Hane Ms. Donna C. Debrodt 《The Journal of Technology Transfer》1985,10(1):1-7
A recent study conducted by Pacific Northwest Laboratory (PNL) evaluated technical information transfer from Japan to the United States. This evaluation was part of a larger assessment of international monitoring of energy technology development conducted for the U.S. Department of Energy. For this study, U.S. researchers in each of ten selected technical fields were identified and interviewed to obtain their perceptions of information transfer from Japan. Results from these interviews indicated that, although there are major differences among the technical fields, U.S. researchers generally consider information transfer from Japan to the U.S. to be inadequate. Researchers particularly noted the difficulties they have attending conferences in Japan or visiting Japanese research facilities. In contrast, Japanese researchers attend all major conferences and frequently visit laboratories in the U.S. Researchers recommended several steps to improve technology transfer from Japan, including improving the screening and translation of technical material published in Japan, promoting binational seminars and workshops, and encouraging laboratory visits and exchanges of research personnel. 相似文献