全文获取类型
收费全文 | 1823篇 |
免费 | 124篇 |
专业分类
1947篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2021年 | 21篇 |
2020年 | 32篇 |
2019年 | 137篇 |
2018年 | 76篇 |
2017年 | 83篇 |
2016年 | 141篇 |
2015年 | 105篇 |
2014年 | 103篇 |
2013年 | 322篇 |
2012年 | 103篇 |
2011年 | 111篇 |
2010年 | 87篇 |
2009年 | 69篇 |
2008年 | 87篇 |
2007年 | 83篇 |
2006年 | 49篇 |
2005年 | 22篇 |
2004年 | 44篇 |
2003年 | 38篇 |
2002年 | 22篇 |
2001年 | 22篇 |
2000年 | 32篇 |
1999年 | 4篇 |
1998年 | 14篇 |
1997年 | 18篇 |
1996年 | 13篇 |
1995年 | 17篇 |
1994年 | 12篇 |
1993年 | 6篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 5篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1977年 | 8篇 |
1976年 | 3篇 |
1974年 | 4篇 |
1969年 | 1篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1951年 | 1篇 |
1948年 | 1篇 |
排序方式: 共有1947条查询结果,搜索用时 0 毫秒
21.
22.
Aura Korppi‐Tommola 《Scandinavian journal of history》2013,38(1-2):181-191
23.
24.
25.
26.
Nancy Scheper‐Hughes 《Anthropology today》2015,31(4):26-27
This narrative deals with the author's experiences while attending a human trafficking panel at the Pontifical Academy of Social Sciences (PASS) in the Casina Pio IV, Vatican City, 7–21 April 2015. 相似文献
27.
John Barker Anne Marie Tietjen 《Oceania; a journal devoted to the study of the native peoples of Australia, New Guinea, and the Islands of the Pacific》1990,60(3):217-234
The Maisin women of northeastern Papua New Guinea are among the last coastal Papuans to tattoo their faces. This article first describes the techniques and social process of Maisin tattooing. We then examine the resilience of the custom in light of changes in puberty rites and notions of gender. We argue that these contexts have lost their cultural salience as a result of the Maisins' incorporation into the larger Papua New Guinea society. Tattooing has acquired new significance as a marker of cultural identity in a multicultural setting and as a sign of the Maisin people's commercial success as makers of indigenous art. 相似文献
28.
The Trèves zinc–lead deposit is one of several Mississippi Valley‐type (MVT) deposits in the Cévennes region of southern France. Fluid inclusion studies show that the ore was deposited at temperatures between approximately 80 and 150°C from a brine that derived its salinity mainly from the evaporation of seawater past halite saturation. Lead isotope studies suggest that the metals were extracted from local basement rocks. Sulfur isotope data and studies of organic matter indicate that the reduced sulfur in the ores was derived from the reduction of Mesozoic marine sulfate by thermochemical sulfate reduction or bacterially mediated processes at a different time or place from ore deposition. The large range of δ34S values determined for the minerals in the deposit (12.2–19.2‰ for barite, 3.8–13.8‰ for sphalerite and galena, and 8.7 to ?21.2‰ for pyrite), are best explained by the mixing of fluids containing different sources of sulfur. Geochemical reaction path calculations, based on quantitative fluid inclusion data and constrained by field observations, were used to evaluate possible precipitation mechanisms. The most important precipitation mechanism was probably the mixing of fluids containing different metal and reduced sulfur contents. Cooling, dilution, and changes in pH of the ore fluid probably played a minor role in the precipitation of ores. The optimum results that produced the most metal sulfide deposition with the least amount of fluid was the mixing of a fluid containing low amounts of reduced sulfur with a sulfur‐rich, metal poor fluid. In this scenario, large amounts of sphalerite and galena are precipitated, together with smaller quantities of pyrite precipitated and dolomite dissolved. The relative amounts of metal precipitated and dolomite dissolved in this scenario agree with field observations that show only minor dolomite dissolution during ore deposition. The modeling results demonstrate the important control of the reduced sulfur concentration on the Zn and Pb transport capacity of the ore fluid and the volumes of fluid required to form the deposit. The studies of the Trèves ores provide insights into the ore‐forming processes of a typical MVT deposit in the Cévennes region. However, the extent to which these processes can be extrapolated to other MVT deposits in the Cévennes region is problematic. Nevertheless, the evidence for the extensive migration of fluids in the basement and sedimentary cover rocks in the Cévennes region suggests that the ore forming processes for the Trèves deposit must be considered equally viable possibilities for the numerous fault‐controlled and mineralogically similar MVT deposits in the Cévennes region. 相似文献
29.
Gabriel Colletis 《European Planning Studies》1993,1(2):169-180
A region's technology potential can be developed in three ways: public finding; private investment (by business); and an intermediate area which ensures coherence between the public and private sectors, and which is mainly to be seen in interface structures between universities and business. After presenting these ways for Rhône‐Alpes, the paper introduces the regional policy to promote science and technology. According to French centralized political structure, the regional government acts as a lever. The region's innovation‐oriented policy, which should not be confused with a research‐oriented policy, has the impact of aiming all action at improving the technological environment of business, and at facilitating their economic development by integrating new technologies. Similarities between Rhône‐Alpes and Baden‐Würtemberg have led these two regions to cooperate increasingly in the fields of science and technology. The ‘four motor‐regions for Europe’ (with Lombardia and Catalonia) experiment in the field of new‐material investment cooperation could be useful if we think of the process aimed at strengthening integration in the European Community. 相似文献
30.