首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1933篇
  免费   327篇
  2024年   2篇
  2023年   23篇
  2022年   3篇
  2021年   24篇
  2020年   46篇
  2019年   134篇
  2018年   163篇
  2017年   135篇
  2016年   176篇
  2015年   123篇
  2014年   116篇
  2013年   404篇
  2012年   116篇
  2011年   114篇
  2010年   83篇
  2009年   64篇
  2008年   79篇
  2007年   75篇
  2006年   47篇
  2005年   21篇
  2004年   37篇
  2003年   33篇
  2002年   28篇
  2001年   30篇
  2000年   32篇
  1999年   6篇
  1998年   15篇
  1997年   21篇
  1996年   14篇
  1995年   18篇
  1994年   15篇
  1993年   4篇
  1992年   7篇
  1991年   3篇
  1987年   3篇
  1986年   2篇
  1985年   3篇
  1982年   5篇
  1980年   4篇
  1979年   4篇
  1978年   2篇
  1977年   6篇
  1976年   2篇
  1975年   1篇
  1974年   2篇
  1972年   2篇
  1971年   2篇
  1969年   2篇
  1968年   3篇
  1951年   1篇
排序方式: 共有2260条查询结果,搜索用时 266 毫秒
71.
In this article, I explore the parallel responses of two groups of colonial subjects who were confronted with the institutional changes that occurred in the context of Enlightenment ideas in eighteenth-century Mexico: creole clerics headed by the Jesuit Francisco Javier Clavijero; and native religious men who petitioned to colonial authorities and the Crown for additional spaces for the education of indigenous men. I explore some of the interactions between creole clerics—often referred to as creole patriots—and native elites in the schools of central Mexico, and efforts by indigenous noble men to broaden the opportunities for natives to join the ranks of the Church and to receive a higher education. To this end, I build on the scholarship that has made evident how the hegemonic program of Bourbon reforms, which was inspired by the Enlightenment, was not a top-down plan implemented successfully and equally across the continent but rather a series of contested interpretations. This article contributes to the recent shift in the scholarship on the Enlightenment that acknowledges cross-cultural global exchanges by arguing that certain groups of natives in central Mexico, and a particular group of American-born clerics, participated actively in building a pragmatic version of the Enlightenment that responded to their local realities and contributed to a globalized understanding of enlightened ideas.  相似文献   
72.
73.
This article introduces latent trajectory models (LTMs), an approach often employed in social sciences to handle longitudinal data, to the arena of GIScience, particularly space‐time analysis. Using the space‐time data collected at county level for the whole United States through webpage search on the keyword “climate change,” we show that LTMs, when combined with eigenvector filtering of spatial dependence in data, are very useful in unveiling temporal trends hidden in such data: the webpage‐data derived popularity measure for climate change has been increasing from December 2011 to March 2013, but the increase rate has been slowing down. In addition, LTMs help reveal potential mechanisms behind observed space‐time trajectories through linking the webpage‐data derived popularity measure about climate change to a set of socio‐demographic covariates. Our analysis shows that controlling for population density, greater drought exposure, higher percent of people who are 16 years old or above, and higher household income are positively predictive of the trajectory slopes. Higher percentages of Republicans and number of hot days in summer are negatively related to the trajectory slopes. Implications of these results are examined, concluding with consideration of the potential utility of LTMs in space‐time analysis and more generally in GIScience.  相似文献   
74.
Metallurgical analyses and chemical characterizations were carried out on historical cannonballs from the Fortress of San Juan de Ulúa, Veracruz, México. Cannonballs dating from the 18th and 19th centuries share metallurgical characteristics similar to those of material coming from a shipment of ammunition found in the wreck of a sunken French ship from the battle of Trafalgar. The analyses show that the base material is grey cast iron with a carbon equivalent of 4.94 and a ferritic–perlitic matrix, in which the high phosphorus content has led to the formation of iron phosphide compounds in conjunction with a homogeneous distribution of carbon graphite flakes of Type C. In addition, corrosion products from samples revealed the presence of various crystalline iron compounds (X‐ray diffraction), mostly highly chlorinated iron compounds identified as akaganeite. X‐ray fluorescence identified various characteristics of the corrosion products as a function of the sampling depth. FT–IR spectroscopy revealed that the main difference between the corrosion products (internal and external) is determined by the number of organic species. Differential scanning calorimetry corroborated that these corrosion products are thermally stable compounds at elevated temperatures.  相似文献   
75.
The Akko 1 shipwreck was an Egyptian armed vessel, built at the beginning of the 19th century. A wooden saw handle and a box containing iron nails and two split pins were discovered towards the stern. Given their function, location and context, these were part of the ship's carpenter's tools and accessories. A methodology was developed for conducting systematic metallurgical analysis in order to understand the manufacturing process of the surviving ironwork items, as well as to enlarge our knowledge regarding ironworking technologies during the early 19th century. Such methodology may assist in the future understanding of the technological evolution of similar wrought‐iron objects. The results demonstrated that the artefacts have a wrought‐iron heterogeneous microstructure and were manufactured by hot‐working prior to surface hardening by pack carburization.  相似文献   
76.
77.
78.
The objective of this paper is to assess an approach to statistical modeling of point referenced establishment data that permit inclusion of “environmental” or establishment‐specific covariates and specific forms of interestablishment interaction. Gibbs models are used to decompose the conditional intensity of the spatial point process into trend and interaction components. The trend is composed of access measures (primarily different classes of roads) and three different interaction processes are tested: Geyer, area interaction, and Strauss hard core. While the models used have proved to be useful in ecology, we are unaware of any applications to establishment or firm data. In empirical application, the models yield intuitively appealing results for the trend component, and the ability to specify the interaction component gives deeper insights into interestablishment spatial dynamics than any previously published methods.  相似文献   
79.
We examine the relationship between individual commuting behavior and household responsibilities, with a focus on gender differences in that relationship. Using the Dutch Time Use Survey for the years 2000 and 2005, we analyze the relationship between commuting time, home production, and childcare. To deal with reverse causality, we use Propenstity Score Matching techniques to obtain imputed data for individuals. We find that the effect of home production on commuting time for women is more than double that for men, while childcare time has an effect on women's commuting behavior only. Our results shedding light on the Household Responsibility Hypothesis.  相似文献   
80.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号