全文获取类型
收费全文 | 153篇 |
免费 | 11篇 |
出版年
2024年 | 2篇 |
2023年 | 1篇 |
2021年 | 1篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 16篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 5篇 |
2014年 | 5篇 |
2013年 | 38篇 |
2012年 | 7篇 |
2011年 | 5篇 |
2010年 | 10篇 |
2009年 | 5篇 |
2008年 | 4篇 |
2007年 | 7篇 |
2006年 | 4篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1997年 | 1篇 |
1993年 | 1篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1980年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有164条查询结果,搜索用时 15 毫秒
11.
12.
13.
ABSTRACT This paper examines the impacts of measures to reduce emissions from buses, cars, and two‐wheelers in Mumbai, India. We have considered three possible policies: conversion of diesel buses to CNG, an increase in the price of gasoline and a tax on vehicle ownership. Our results suggest that the most effective policy to reduce emissions from passenger vehicles—in terms of the total number of tons of PM10 reduced—is to convert diesel buses to CNG. The conversion of 3,391 diesel buses to CNG would result in an emissions reduction of 663 tons of PM10 per year, 14 percent of total emissions from transport. 相似文献
14.
This article analyses the evolution of Community expenditure, on the basis of the data given in the budget and in the EDF, from the origin of the process in 1957 until the year 2002, the last definitive figures. The technique of principal component factor analysis has been applied to these variables. The basic objective of this study is to detect the interrelationships among the policies of the Union and to effect a classification of them, in order to detect the priorities of the European project and to estimate the dimension of the impact of its policies during the period. 相似文献
15.
John Edward Terrell John P. Hart Sibel Barut Nicoletta Cellinese Antonio Curet Tim Denham Chapurukha M. Kusimba Kyle Latinis Rahul Oka Joel Palka Mary E. D. Pohl Kevin O. Pope Patrick Ryan Williams Helen Haines John E. Staller 《Journal of Archaeological Method and Theory》2003,10(4):323-368
Harvesting different species as foods or raw materials calls for differing skills depending on the species being harvested and the circumstances under which they are being taken. In some situations and for some species, the tactics used are mainly behavioral—that is, people adjust, or adapt, their own actions to fit the behavior and circumstances of the species they are taking. Under other circumstances and for other species, the skills and tactics used may call for greater environmental preparation or manipulation. Therefore, instead of trying to distinguish people today and in the past as either foragers or farmers, it makes sense to define human subsistence behavior as an interactive matrix of species and harvesting tactics, that is, as a provisions spreadsheet. 相似文献
16.
17.
Jorge Machado Francisco J. Molina Cristo M. Hernández Antonio Tarriño Bertila Galván 《Archaeological and Anthropological Sciences》2017,9(8):1715-1743
The superposition of anthropogenic remains usually results in archaeological palimpsests, hindering an accurate characterization of the behavior underlying such remains. Aimed at facing this methodological constraint in the study of Palaeolithic contexts, we present a contextual approach to Neanderthal settlement dynamics based on an understanding of lithic assemblage formation processes. We focused on a set of lithic artifacts from the Middle Palaeolithic site of El Salt. With the goal of isolating temporally constrained units of behavioral analysis, we analyzed the spatial distribution of lithic, faunal and combustion remains. Then, the lithic records from each of the resulting units were analyzed from a genetic and technical perspective. This goal was achieved by identifying lithic Raw Material Units (RMU) through observations on reduction processes, refits and their spatial distribution. Our results suggest that El Salt SU X lithic remains represent several diachronic human occupation episodes and different site functions. This study illustrates the benefit of investigating lithic assemblage formation processes to alleviate the palimpsest problem in Palaeolithic contexts. 相似文献
18.
19.
The Old and the New: Qualifying City Systems in the World with Classical Models and New Data 下载免费PDF全文
Robin Cura Clémentine Cottineau Elfie Swerts Cosmo Antonio Ignazzi Anne Bretagnolle Celine Vacchiani‐Marcuzzo Denise Pumain 《Geographical analysis》2017,49(4):363-386
Zipf's rank‐size rule, lognormal distribution, and Gibrat's urban growth models are considered as summarizing fundamental properties of systems of cities. In this article, they are used as statistical benchmarks for comparing the shapes of urban hierarchies and evolutionary trends of seven systems of cities in the world including BRICS, Europe, and United States. In order to provide conclusions that avoid the pitfalls of too small samples or uncontrolled urban definitions, these models are tested on some 20,000 urban units whose geographically significant delineations were harmonized in each country over 50 years between 1960 and 2010. As a result, if the models appear not always statistically valid, their usefulness is confirmed since the observed deviations from empirical data remain limited and can often be interpreted from the geohistorical context of urbanism proper to each world region. Moreover, the article provides new free software which authorizes the reproducibility of our experiments with our data bases as well as with complementary data. 相似文献
20.
This paper considers the “share‐altering” technical change hypothesis in a spatial general equilibrium model where individuals have different levels of skills. Building on a simple Cobb‐Douglas production function, our model shows that the implementation of skill‐biased technologies requires a sufficient proportion of highly educated individuals. Moreover, when technical progress disproportionately replaces middle‐skill jobs, the local distribution of skills will exhibit “fat‐tails,” where the proportion of both highly skilled and low‐skilled workers increases. These and several other predictions of the model are consistent with recent existing evidence, and avoid some major criticism against the “canonical” CES framework. 相似文献