全文获取类型
收费全文 | 6762篇 |
免费 | 62篇 |
专业分类
各国政治 | 261篇 |
工人农民 | 296篇 |
世界政治 | 618篇 |
外交国际关系 | 281篇 |
法律 | 4027篇 |
中国政治 | 61篇 |
政治理论 | 1258篇 |
综合类 | 22篇 |
出版年
2021年 | 44篇 |
2020年 | 83篇 |
2019年 | 121篇 |
2018年 | 151篇 |
2017年 | 145篇 |
2016年 | 155篇 |
2015年 | 90篇 |
2014年 | 146篇 |
2013年 | 683篇 |
2012年 | 164篇 |
2011年 | 178篇 |
2010年 | 156篇 |
2009年 | 167篇 |
2008年 | 200篇 |
2007年 | 196篇 |
2006年 | 176篇 |
2005年 | 175篇 |
2004年 | 186篇 |
2003年 | 161篇 |
2002年 | 147篇 |
2001年 | 323篇 |
2000年 | 291篇 |
1999年 | 210篇 |
1998年 | 94篇 |
1997年 | 90篇 |
1996年 | 61篇 |
1995年 | 64篇 |
1994年 | 59篇 |
1993年 | 52篇 |
1992年 | 134篇 |
1991年 | 152篇 |
1990年 | 141篇 |
1989年 | 138篇 |
1988年 | 121篇 |
1987年 | 135篇 |
1986年 | 109篇 |
1985年 | 107篇 |
1984年 | 105篇 |
1983年 | 90篇 |
1982年 | 61篇 |
1981年 | 82篇 |
1980年 | 39篇 |
1979年 | 76篇 |
1978年 | 50篇 |
1975年 | 39篇 |
1974年 | 57篇 |
1973年 | 61篇 |
1972年 | 45篇 |
1971年 | 35篇 |
1970年 | 32篇 |
排序方式: 共有6824条查询结果,搜索用时 0 毫秒
281.
Michael C. Taylor Ph.D. Terry L. Laber B.S. Paul E. Kish M.Sc. Glynn Owens Ph.D. Nikola K. P. Osborne Ph.D. 《Journal of forensic sciences》2016,61(4):922-927
This study was designed to produce the first baseline measure of reliability in bloodstain pattern classification. A panel of experienced bloodstain pattern analysts examined over 400 spatter patterns on three rigid non‐absorbent surfaces. The patterns varied in spatter type and extent. A case summary accompanied each pattern that either contained neutral information, information to suggest the correct pattern (i.e., was positively biasing), or information to suggest an incorrect pattern (i.e., was negatively biasing). Across the variables under examination, 13% of classifications were erroneous. Generally speaking, where the pattern was more difficult to recognize (e.g., limited staining extent or a patterned substrate), analysts became more conservative in their judgment, opting to be inconclusive. Incorrect classifications increased as a function of the negatively biasing contextual information. The implications of the findings for practice are discussed. 相似文献
282.
Danielle Flores M.S. Amy L. Miller M.S. Angelique Showman M.S. Caitlyn Tobita Lori M. N. Shimoda B.S. Carl Sung B.S. Alexander J. Stokes Ph.D. Jeffrey K. Tomberlin Ph.D. David O. Carter Ph.D. Helen Turner Ph.D. 《Journal of forensic sciences》2016,61(6):1578-1587
Entomological protocols for aging blowfly (Diptera: Calliphoridae) larvae to estimate the time of colonization (TOC) are commonly used to assist in death investigations. While the methodologies for analyzing fly larvae differ, most rely on light microscopy, genetic analysis, or, more rarely, electron microscopy. This pilot study sought to improve resolution of larval stage in the forensically important blowfly Chrysomya rufifacies using high‐content fluorescence microscopy and biochemical measures of developmental marker proteins. We established fixation and mounting protocols, defined a set of measurable morphometric criteria and captured developmental transitions of 2nd instar to 3rd instar using both fluorescence microscopy and anti‐ecdysone receptor Western blot analysis. The data show that these instars can be distinguished on the basis of robust, nonbleaching, autofluorescence of larval posterior spiracles. High‐content imaging techniques using confocal microscopy, combined with morphometric and biochemical techniques, may therefore aid forensic entomologists in estimating TOC. 相似文献
283.
Erwin J. A. T. Mattijssen M.Sc. K. Dieter H. Pater M.Sc. Reinoud D. Stoel Ph.D. 《Journal of forensic sciences》2016,61(6):1456-1460
For shooting scene reconstruction purposes, knowledge about the ricochet behavior of bullets provides valuable information. In this study, the critical ricochet angles of four cartridge types were established on plain float glass. The estimates of the critical ricochet angles varied between cartridge types and were 21.0° for .32 Auto FMJ bullets, 15.8° for 9 mm Luger FMJ bullets, 17.6° for .45 Auto FMJ bullets, and 21.3° for 9 mm Luger, Action NP bullets. The corresponding ricochet and deflection angles per incidence angle varied depending on the state of the ricocheted bullets. The mean ricochet angles are always lower than the corresponding angles of incidence, and the mean ricochet angles for the FMJ bullets with undamaged jackets are lower than those of bullets where the jacket is either damaged or the bullet partially ricocheted and partially perforated. Mean ricochet angles are lower for undamaged FMJ bullets than for undamaged Action NP bullets. 相似文献
284.
Ranjan Kumar Mohanty Biresh K. Sahoo Pradipta K. Chaudhury 《Journal of Public Affairs (14723891)》2021,21(1):e2122
The prime objective of this article is to construct a robust macroeconomic performance (MEP) index of the Indian economy using the data envelopment analysis (DEA) approach. Seven major macro indicators, namely, economic growth, employment rate, terms of trade, inflation rate, fiscal deficit, pollution, and climate change are used to compute MEP and Eco‐MEP indices of the Indian economy from 1980–1981 to 2018–2019. Overall, both the MEP and Eco‐MEP index scores have quite similar best performing years worst performing years, and have also captured the major events that affected adversely the Indian economy during the past decades. The trend in the overall performance of the Indian economy was better in the 1980s and the 1990s but has deteriorated since 2000. The autoregressive distributed lag bounds testing approaches to cointegration methods are used to test the robustness/utility of these indices. The estimated results show that MEP and Eco‐MEP have a positive impact on private investment, foreign investment inflows, foreign direct investment, and a negative effect on the current account deficit. Hence, the suggested composite MEP index is stable, robust and truly captures the economic performance of India. The constructed MEP composite index may be used by foreign investors, rating agencies, private investors, and policymakers for their planning and decision‐making processes. 相似文献
285.
AbstractDespite an overall decrease in residential mobility after the 2007 housing crisis, many households, particularly those that are low income, continue to move in pursuit of a better life. Traditional theories of residential mobility suggest that mobility will occur when housing and transportation costs are cumulatively greater than the cost of moving to a new location. At the same time, the influence of these factors is not likely to be uniform across geographic contexts or for moves up or down the metropolitan hierarchy. Our analysis examines how well affordability measures explain patterns of county-level residential mobility. Specifically, we contrast conventional measures of affordability focused on the ratio of income to housing expense with measures of location affordability that factor in both housing and transportation costs. We find that whereas households tend to move from lower to higher cost locations, transit affordability at the destination plays an important role in mobility decisions. 相似文献
286.
Social Justice Research - A confirmatory factor analysis (CFA) was used on the Belief in a Just World Scale (BJW; Lucas, Zhdanova & Alexander in J Individ Diff 32:14–25, 2011) to test... 相似文献
287.
John K. Mullen Martin Williams Ronald L. Moomaw 《Journal of policy analysis and management》1996,15(1):51-67
This study focuses on the role of public capital stock in contributing to interstate differences in productive efficiency in manufacturing. Our motivation is to assess the role of public capital as a source of persistent regional variations in efficiency, and thus determine if public infrastructure policies might reasonably be expected to alter the competitive environment of a state's manufacturing sector. We use a stochastic frontier production function model, explicitly incorporating infrastructure capital, to examine the relative performance of the aggregate manufacturing sector across states and over time. We calculate an index of productive efficiency and estimate the determinants of statewide variations in it. These results show that variations in per capita infrastructure stocks significantly affect manufacturing efficiency. Considering the behavior of public capital as both a direct and an indirect input furthers our understanding of the role of infrastructure and its implications for regional economic development policies. 相似文献
288.
Folk Johanna B. Brown Larry K. Marshall Brandon D. L. Ramos Lili M. C. Gopalakrishnan Lakshmi Koinis-Mitchell Daphne Tolou-Shams Marina 《Journal of youth and adolescence》2020,49(1):238-251
Journal of Youth and Adolescence - Court-involved youth exhibit high rates of psychiatric symptoms, substance use, and delinquency, yet little is known about the contributing roles of caregiver and... 相似文献
289.
290.
Trade has again emerged as a controversial issue in America, yet we know little about the ideas that guide American thinking on these questions. By combining traditional survey methods with experimental manipulation of problem content, this study explores the ideational landscape among elite Americans and pays particular attention to how elite Americans combine their ideas about commerce with their ideas about national security and social justice. We find that most American leaders think like intuitive neoclassical economists and that only a minority think along intuitive neorealist or Rawlsian lines. Among the mass public, in contrast, a majority make judgments like intuitive neorealists and intuitive Rawlsians. Although elite respondents see international institutions as promising vehicles in principle, in practice they favor exploiting America's advantage in bilateral bargaining power over granting authority to the World Trade Organization. The distribution of these ideas in America is not arrayed neatly along traditional ideological divisions. To understand the ideational landscape, it is necessary to identify how distinctive mentaal models—mercantilist, neorealist, egalitarian, and neoclassical economic—sensitize or desensitize people to particular aspects of geopolitical problems, an approach we call cognitive interactionism. 相似文献