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121.
Bradley T. De GREGORIO Rhonda M. STROUD George D. CODY Larry R. NITTLER A. L. DAVID KILCOYNE Sue WIRICK 《Meteoritics & planetary science》2011,46(9):1376-1396
Abstract– Carbonaceous matter in Stardust samples returned from comet 81P/Wild 2 is observed to contain a wide variety of organic functional chemistry. However, some of this chemical variety may be due to contamination or alteration during particle capture in aerogel. We investigated six carbonaceous Stardust samples that had been previously analyzed and six new samples from Stardust Track 80 using correlated transmission electron microscopy (TEM), X‐ray absorption near‐edge structure spectroscopy (XANES), and secondary ion mass spectroscopy (SIMS). TEM revealed that samples from Track 35 containing abundant aliphatic XANES signatures were predominantly composed of cometary organic matter infilling densified silica aerogel. Aliphatic organic matter from Track 16 was also observed to be soluble in the epoxy embedding medium. The nitrogen‐rich samples in this study (from Track 22 and Track 80) both contained metal oxide nanoparticles, and are likely contaminants. Only two types of cometary organic matter appear to be relatively unaltered during particle capture. These are (1) polyaromatic carbonyl‐containing organic matter, similar to that observed in insoluble organic matter (IOM) from primitive meteorites, interplanetary dust particles (IDPs), and in other carbonaceous Stardust samples, and (2) highly aromatic refractory organic matter, which primarily constitutes nanoglobule‐like features. Anomalous isotopic compositions in some of these samples also confirm their cometary heritage. There also appears to be a significant labile aliphatic component of Wild 2 organic matter, but this material could not be clearly distinguished from carbonaceous contaminants known to be present in the Stardust aerogel collector. 相似文献
122.
Sue Ruddick 《Urban geography》2013,34(8):1113-1130
The anthropological machine is the discursive framework, the dispositif that grounds “Western man” in a sense of civility, secured through a violent division within and between the human and nonhuman: not the after-effect of the civilizing act but its very foundation. This paper explores Agamben’s machine at multiple sites: in its expression in everyday lives of urban citizens, and its legitimation of capitalist urbanization on broader spatial and temporal scales, its “worlding” through planetary urbanization and normalization of climate change. Complicit in capitalist urbanization and climate change, the anthropological machine has acted as a “switch point” since the 1600s. It now frames an emergent response: triage as the inevitable sacrifice of some peoples and parts of the planet to preserve others. If the urban is to become the site of mondialization, confronting the apparent inevitability of triage we must think beyond the either-or of a people or a planet. Thought in relation to the urban, the anthropological machine offers a meeting ground between urban political economy and assemblage urbanism. It enables us to situate the Anthropocene and differentiate the urban. But it also exposes a deep divide between scholars reframing the human beyond “Western man”: between those for whom the more-than-human expresses the dreams of a biophilic city and those for whom the less-than-human is increasingly its living nightmare. 相似文献
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ABSTRACT. Between the time of its opening, in 1923, and 1956, when the last vestiges of official segregation were swept away by the courts, the Carroll Park Municipal Golf Course in Baltimore, Maryland, figured prominently in the struggle to desegregate the city's recreational facilities. In this article we use historical sources to examine how access to Carroll Park was shaped by issues of race and ethnicity during the first half of the twentieth century, focusing specifically on the role the park played in the struggle to desegregate Baltimore's golf courses. We also consider how this victory ultimately contributed to desegregation at the city's other recreational facilities, including ball fields and swimming pools. 相似文献
126.
The distribution of seven submerged aquatic pest plants is reported. Lake vegetation surveys recorded pest plants in 27.9% of 344 lakes, with two species co‐occurring in 5.8%, and three species in 2.6% of lakes. Egeria densa was most frequent (15.4% of lakes), followed by Ceratophyllum demersum (9.0%), Lagarosiphon major (7.3%), and Utricularia gibba (5.5%). Spread since 2000 has continued for five pest plants, with 34 lakes invaded by U. gibba over 2004–08 alone. Early regional sites in proximity to human population centres were likely plant liberations and numerous potential founder colonies remain in garden ponds. Human activities were important for inter‐lake dispersal, with the exception of bird‐dispersed U. gibba. Significant lake associations between pest plants, and with presence of six exotic fish species, suggest common dispersal pathways and similar introduction risks. Therefore, predictions of future spread should be possible based on sources, dispersal pathways, and identifying key risk factors for lakes. 相似文献
127.
Maryd De Wemton John S. Clayton Rohan D. S. Wells Chris C. Tanner Suzanne T. Miller 《新西兰海洋与淡水研究杂志》2013,47(2):145-151
The submerged vegetation of Lakes Sumner, Marion, Katrine, Taylor, and Sheppard was surveyed in May 1987. These high‐altitude lakes lie at c. 600 m a.s.l., within the largely unmodified upper Hurunui catchment. Submerged vegetation was diverse and included numerous short shallow‐water species, dense swards of Isoetes alpinus, low covers of taller native vascular plants, and charophyte meadows beyond the depth limit of vascular plants to a maximum of 15 m. A sparse deepwater bryophyte community was observed from 11 to 32 m depth in Lake Sumner. Displacement of native vegetation by dense growths of the adventive oxygen weed Elodea canadensis over mid‐depths of 3–6 m was noted in all lakes, except Lake Marion. 相似文献
128.
Sue Wells 《Marine pollution bulletin》2009,58(1):20-23
Dynamite fishing, although illegal, has resurfaced in recent years as a major threat to the reefs of northern Tanzania. This is despite the fact that institutional arrangements for co-management of the inshore fisheries by local communities and the district governments have been put in place and, through a 12-year donor-funded programme, numerous activities undertaken to build capacity for effective fisheries management. The use of dynamite is having widespread negative impacts, including damage to the reefs and their long-term productivity, deterrence of tourism investors, and potential threat to the large population of coelacanths in the area. The dynamite fishers are able to continue, even though enforcement efforts have been stepped up, because they are members of influential families or otherwise well-connected. Previous similar cases in Tanzania, and examples from elsewhere in the world, suggest that a major initiative is now needed to develop a zero-tolerance approach on the part of fishers and local and national leaders, that will shame the dynamiters through peer pressure, promote full implementation of sanctions and penalties by the judiciary, and lead to public recognition of and support for the work of the enforcement agencies. 相似文献
129.
正Climate change and its impacts have become topical issues of global news, scientific research and conferences. Environmental Geosciences incorporate the various disciplines of geosciences and their multifaceted interactions with life. Research discussions on the interaction of climate change, geosciences and environment may often be blur, and Schmidt-Thoméet al.(2010) stated that"Often past climate changes that can be deduced from geological records may help in understanding the speed of potential climate change effects, i.e. how quickly have sea levels changed, how drastic has nature reacted to ups and downs in temperature, etc. These analyses of past events help in giving outlooks on potential changes in our living environment. It is also of important to understand the magnitude and potential effects of extreme events, such as droughts and floods". 相似文献
130.
The significance of late-stage fracturing in the European Alps in a large geodynamic context is reappraised by studying brittle deformations over the entire belt. In the internal Western Alps, paleostress datasets display a major occurrence of orogen-parallel extension resulting in normal faulting and associated strike-slip mode. There the direction of subhorizontal extension rotates with the bending of the Alpine belt. In the Central Alps, paleostress tensors also indicate orogen-parallel extensional regimes, both in the Bergell area and the Lepontine Dome, where the brittle structures are associated with ductile structures related to the formation of large-scale upright folds that accommodate most of the collisional shortening due to the north-directed component of the movement of the South-Alpine indenter. This brittle deformation phase is of Miocene age and is coeval with the propagation of the Alpine front toward the external Alpine domains. In the Eastern Alps, brittle deformation of the Tauern Window displays an overwhelming occurrence of orogen-parallel normal faulting and associated strike-slip regimes again, which is inferred to be driven by lateral extrusion of the orogenic wedge toward the Pannonian basin, partly due to indentation on the Dolomites indenter. The major orogen-parallel extensional signal of the brittle Cenozoic deformations appears remarkably stable all over the internal Alps. Extensional brittle structures are part of a late phase of collisional deformation, during which the propagation of the Alpine front of the Western Alps and the northward movement of the Southern Alpine and the Dolomites indenters in the Central and Eastern Alps were accommodated by orogen-parallel extension in the inner zones, at the scale of the entire chain. 相似文献