全文获取类型
收费全文 | 62092篇 |
免费 | 886篇 |
国内免费 | 602篇 |
专业分类
测绘学 | 1601篇 |
大气科学 | 4363篇 |
地球物理 | 12115篇 |
地质学 | 21505篇 |
海洋学 | 5728篇 |
天文学 | 14489篇 |
综合类 | 120篇 |
自然地理 | 3659篇 |
出版年
2021年 | 576篇 |
2020年 | 603篇 |
2019年 | 705篇 |
2018年 | 1429篇 |
2017年 | 1332篇 |
2016年 | 1687篇 |
2015年 | 936篇 |
2014年 | 1554篇 |
2013年 | 3128篇 |
2012年 | 1766篇 |
2011年 | 2439篇 |
2010年 | 2251篇 |
2009年 | 2952篇 |
2008年 | 2556篇 |
2007年 | 2625篇 |
2006年 | 2489篇 |
2005年 | 1983篇 |
2004年 | 1934篇 |
2003年 | 1844篇 |
2002年 | 1761篇 |
2001年 | 1557篇 |
2000年 | 1483篇 |
1999年 | 1264篇 |
1998年 | 1257篇 |
1997年 | 1243篇 |
1996年 | 991篇 |
1995年 | 976篇 |
1994年 | 933篇 |
1993年 | 823篇 |
1992年 | 787篇 |
1991年 | 713篇 |
1990年 | 770篇 |
1989年 | 729篇 |
1988年 | 695篇 |
1987年 | 777篇 |
1986年 | 680篇 |
1985年 | 878篇 |
1984年 | 929篇 |
1983年 | 867篇 |
1982年 | 802篇 |
1981年 | 792篇 |
1980年 | 710篇 |
1979年 | 648篇 |
1978年 | 614篇 |
1977年 | 621篇 |
1976年 | 532篇 |
1975年 | 538篇 |
1974年 | 524篇 |
1973年 | 526篇 |
1972年 | 316篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
122.
We present an evaluation of the procedure by which model prediction bias is examined in palaeolimnological transfer function inference models. We argue that most of the prediction biases commonly reported in the literature are, in fact, fallacious, and are the artificial consequence of the inappropriate manner in which residuals are traditionally examined. We show that the extent of the specious model bias is entirely predictable from first principles and is essentially determined by the strength of the predictive model. We suggest that the analysis of residuals should always be examined as a function of the model's predictions and we discuss the implications of the old and new approaches. 相似文献
123.
CLARISSA T. KIMBER 《Geographical review》2004,94(3):263-283
ABSTRACT. Investigations of dooryard gardens, kitchen gardens, home gardens, and houselot gardens fall unequally into one of three groupings. The first are those that treat the plants in the gardens as biological entities and define a space considered a culturally controlled biological community or habitat. The second are those that consider plants cultural traits and the space defined by their positions a setting for household activities. The third conceives of plants as design elements within a garden or a landscape that frames a house or provides a setting for formal human performances. Recent decades have witnessed a broadening focus in the study of gardens, from spatial characteristics and biological content to social and cultural concerns such as reciprocity networks, contested spaces, and the concept of “dwelling.” 相似文献
124.
125.
126.
127.
128.
129.
130.
D. Q. Bowen 《Geological Journal》1973,8(2):207-224
The Pleistocene rock-stratigraphic record is accorded more or less traditional time-stratigraphic interpretation which was held widely before application of an Irish developmental model in 1960. The following sequence of events are recognised: (1) Complete glaciation, of indeterminate age, which antedated the raised beach interglacial. (2) The raised beach episode which is shown to be the last (Ipswichian) interglacial. (3) The last (Devensian/Weichselian) glaciation, followed by possible readvance in northwest and northeast Wales; prior and subsequent to glaciation periglacial conditions obtained. It is shown that the Irish model, relying heavily as it does on the equation of rock and time stratigraphy, is inapplicable in Wales. 相似文献