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991.
Kevin L. Shelton Justin M. Beasley Jay M. Gregg Martin S. Appold Stephen F. Crowley James P. Hendry Ian D. Somerville 《Mineralium Deposita》2011,46(8):859-880
A newly discovered, extensive sphalerite-bearing breccia (~7.5 wt.% Zn) is hosted in dolomitised Carboniferous limestones
overlying Ordovician–Silurian metasedimentary rocks on the Isle of Man. Although base metal sulphide deposits have been mined
historically on the island, they are nearly all quartz vein deposits in the metamorphic basement. This study investigates
the origin of the unusual sphalerite breccia and its relationship to basement-hosted deposits, through a combination of petrographic,
cathodoluminescence, fluid inclusion, stable isotope and hydrogeologic modelling techniques. Breccia mineralisation comprises
four stages, marked by episodes of structural deformation and abrupt changes in fluid temperature and chemistry. In stage
I, high-temperature (T
h > 300°C), high-salinity (20–45 wt.% equiv. NaCl) fluid of likely basement origin deposited a discontinuous quartz vein. This
vein was subsequently dismembered during a major brecciation event. Stages II–IV are dominated by open-space filling sphalerite,
quartz and dolomite, respectively. Fluid inclusions in these minerals record temperatures of ~105–180°C and salinities of
~15–20 wt.% equiv. NaCl. The δ34S values of sphalerite (6.5–6.9‰ Vienna-Canyon Diablo troilite) are nearly identical to those of ore sulphides from mines
in the Lower Palaeozoic metamorphic rocks. The δ18O values for quartz and dolomite indicate two main fluid sources in the breccia’s hydrothermal system, local Carboniferous-hosted
brines (~0.5–6.0‰ Vienna standard mean ocean water) and basement-involved fluids (~5.5–11.5‰). Ore sulphide deposition in
the breccia is compatible with the introduction and cooling of a hot, basement-derived fluid that interacted with local sedimentary
brines. 相似文献
992.
James Marcus Bishop Weizhong Chen Adel Hasan Alsaffar Hussain Mahmoud Al-Foudari 《Estuaries and Coasts》2011,34(6):1246-1254
Discharge of the Shatt Al-Arab is believed to be a dominating component of the northern Arabian Gulf’s ecology and largely
responsible for productivity of Kuwait’s fisheries. With major construction of dams on the Tigris and Euphrates Rivers in
Turkey, river discharge has been substantially reduced, and flooding essentially eliminated. We attempted to relate river
flow and shrimp landings indirectly by correlating 19 years of salinity and temperature data from Kuwait’s waters with corresponding
annual shrimp landings. For green tiger prawns (Penaeus semisulcatus), the combination of October salinities and January temperatures provided the best correlation (r = 0.67) with landings in the following shrimping season. For the combined landings of jinga and kiddi shrimps (Metapenaeus affinis and Parapenaeopsis stylifera, respectively), December salinity during season and May temperature prior to season resulted in the best correlation (r = 0.87). Landings of these two species also correlated well with spring and summer temperatures. Under normal conditions,
late winter or early spring temperatures prior to fishing season influence recruitment of the green tiger prawn, whereas December
salinities during harvest season influence the abundance of jinga–kiddi shrimps. With further reductions in the Shatt Al-Arab
discharge and the elimination of flood events, Kuwait’s shrimp landings will most likely decrease over time. 相似文献
993.
Terrorist attacks and natural disasters have potentially severe economic consequences in terms of property damage and business
interruption. However, experience from the September 11 World Trade Center attack and other disasters indicates that the economy
has a great deal of resilience. This refers to the ability to dampen the maximum potential economic output (business interruption)
loss. One of the most prominent sources of resilience is the ability of businesses to reschedule, or recapture, lost production
after the event. Although there have been applications of a fixed parameter recapture factor for each of several aggregated
sectors of the economy, there has been little formal analysis of this resilience action. This study offers a theoretic framework
for analyzing production rescheduling. It distinguishes the major conditions influencing two aspects that have previously
been neglected: (1) the maximum time span over which the rescheduling can take place and (2) the likely decline of the maximum
recapture as the business interruption increases. We divide the relevant time path into two periods after recovery. One is
a function of a recaptured output path after recovery to the status of normal production. The other is a function for the
maximum recaptured production, based on the recaptured output path. The recaptured output path function is assumed to follow
a normal distribution function, and hence, total recaptured output follows the cumulative normal distribution function over
time after productive capacity is restored. Also, we develop a new cumulative normal distribution function for interruption
time duration, which is symmetric with respect to the output axis. This recapture function has unknown parameters. Empirical
data on the recaptured amounts following an actual disaster can be used to estimate the parameters of this function using
simulation methods. 相似文献
994.
In many megacities of the global south, the combination of rapid population growth and high pressure on space for housing,
results in urban growth taking place in areas particularly prone to natural hazards. Dhaka, the capital of Bangladesh, is
no exception to this rule. Many marginal settlements or slums are located on low-lying land at high risk of flooding. This
paper analyzes the vulnerability of slum dwellers in Dhaka and highlights the major factors behind their sensitivity to floods
and their ability to adapt to the related changes. The empirical findings presented are based on a questionnaire survey covering
625 households in five slum areas of Dhaka. Our data suggests that social capital plays an important role with regard to the
ability of slum dwellers to find ways to live with the floods. Regardless of how strongly people are affected, mutual help
and support are dominant features in times of crises. While poorly educated and resourced slum dwellers are highly vulnerable
to external shocks, they still show a surprising capacity to cope with natural calamities. 相似文献
995.
This study analyzes the response of glacier to climate change during the past 49 years in Urumqi River source region, the
Tianshan Mountains of China. The temporal and spatial variations of winter mass balance (bn-w) at different time scales were
analyzed to identify their response to climate change during 1988–2006 (The observation of winter mass balance observation
began in 1988) on the Glacier No.1 at the headwaters of the Urumqi River, Tianshan Mountains, China. The winter accumulation
shows a significantly decreasing trend. The results show that the cumulative values on Glacier No.1 is 2,202 mm water equivalent
during 1988–2006 and the mean values is 116 mm a−1. Furthermore, the trend analysis of the winter mass balance indicates a rapid decrease since 1990, and the mean mass balance
is only 79 mm a−1 during 1997–2006. Winter mass balance correlates well negatively with the total evaporation from September to April (r = −0.68, α = 0.01), and positively with the total precipitation from September to April (r = 0.74, α = 0.01). However, winter mass balance shows a weak correlation with mean minimum air temperature during September
to April (r = −0.35), and runoff on September (r = −0.13). 相似文献
996.
Gonca Gencalioglu-Kuscu 《International Journal of Earth Sciences》2011,100(8):1967-1985
Central Anatolian Volcanic Province (CAVP) is a fine example of Neogene-Quaternary post-collisional volcanism in the Alpine-Mediterranean
region. Volcanism in the Alpine-Mediterranean region comprises tholeiitic, transitional, calc-alkaline, and shoshonitic types
with an “orogenic” fingerprint. Following the orogenic volcanism, subordinate, within-plate alkali basalts (sl) showing little or no orogenic signature are generally reported in the region. CAVP is mainly characterized by widespread
calc-alkaline andesitic-dacitic volcanism with orogenic trace element signature, reflecting enrichment of their source regions
by subduction-related fluids. Cora Maar (CM) located within the Erciyes pull-apart basin, is an example to numerous Quaternary
monogenetic volcanoes of the CAVP, generally considered to be alkaline. Major and trace element geochemical and geochronological
data for the CM are presented in comparison with other CAVP monogenetic volcanoes. CM scoria is basaltic andesitic, transitional-calc-alkaline
in nature, and characterized by negative Nb–Ta, Ba, P and Ti anomalies in mantle-normalized patterns. Unlike the “alkaline”
basalts of the Mediterranean region, other late-stage basalts from the CAVP monogenetic volcanoes are classified as tholeiitic,
transitional and mildly alkaline. They display the same negative anomalies and incompatible element ratios as CM samples.
In this respect, CM is comparable to other CAVP monogenetic basalts (sl), but different from the Meditterranean intraplate alkali basalts. Several lines of evidence suggest derivation of CM and
other CAVP monogenetic basalts from shallow depths within the lithospheric mantle, that is from a garnet-free source. In a
wider regional context, CAVP basalts (sl) are comparable to Apuseni (Romania) and Big Pine (Western Great Basin, USA) volcanics, except the former have depleted Ba
contents. This is a common feature for the CAVP volcanics and might be related to crustal contamination or source characteristics.
Indeed, HFS and other incompatible element ratios suggest the role of crustal contamination in the genesis of the CAVP monogenetic
basalts. 相似文献
997.
On November 4th 2007, along the Grijalva River in the state of Chiapas, Mexico, has occurred one of the largest landslides
ever known. This landslide, known as Juan del Grijalva, destroyed the town of the same name, killing 20 people, and moved 55 million cubic meters of rock and debris down slope
to completely block the Grijalva River. In order to understand the characteristics and factors that triggered the Juan del
Grijalva landslide, geologic studies were conducted at the site. The results indicate that the landslide was composed of a
lithologic sequence of thin-bedded shales and thin to medium-thick-bedded sandstones. This was faulted into several blocks
dipping in the same sense as the mass movement. The main triggering factor was the increment of the pore pressure into the
lithologic unit due to water saturation after 5 days of heavy rain before the incident. According to records from the last
century, the Juan del Grijalva mass movement represents one of the largest mass movements recorded all over the world. The
risk conditions of the area after the landslide lead to the rapid construction of an artificial channel to drain the accumulating
mass of water upstream and therefore prevent a future catastrophic inundation down stream. 相似文献
998.
David L. Naftz Frank J. Millero Blair F. Jones W. Reed Green 《Aquatic Geochemistry》2011,17(6):809-820
Great Salt Lake (GSL) is one of the largest and most saline lakes in the world. In order to accurately model limnological
processes in GSL, hydrodynamic calculations require the precise estimation of water density (ρ) under a variety of environmental conditions. An equation of state was developed with water samples collected from GSL to
estimate density as a function of salinity and water temperature. The ρ of water samples from the south arm of GSL was measured as a function of temperature ranging from 278 to 323 degrees Kelvin
(oK) and conductivity salinities ranging from 23 to 182 g L−1 using an Anton Paar density meter. These results have been used to develop the following equation of state for GSL (σ = ± 0.32 kg m−3):
r- r0 = 184.0 10 6 2 + 1.0 4 70 8*\textS - 1. 2 10 6 1*\textT + 3. 1 4 7 2 1 \textE - 4*\textS 2 + 0.00 1 9 9 \textT 2 - 0.00 1 1 2*\textS*\textT, \rho - \rho^{0} = { 184}.0 10 6 2 { } + { 1}.0 4 70 8*{\text{S}} - 1. 2 10 6 1*{\text{T }} + { 3}. 1 4 7 2 1 {\text{E}} - 4*{\text{S}}^{ 2} + \, 0.00 1 9 9 {\text{T}}^{ 2} - 0.00 1 1 2*{\text{S}}*{\text{T}}, 相似文献
999.
K PEDIADITI F BUONO F POMPIGNA C BOGLIOTTI E NURLU G LADISA G P PETROPOULOS 《Journal of Earth System Science》2011,120(5):949-961
Despite common acknowledgement of the value of protected areas as instruments in ensuring sustainability, and their promotion
for the achievement of policies on halting the loss of biodiversity, there is no common approach today for monitoring and
evaluating them. This paper presents a novel integrated nature conservation management procedure developed to monitor and
evaluate the sustainability of Mediterranean protected areas. This procedure was successfully implemented and formally evaluated
by protected area managers in six Mediterranean countries, results of which are presented here together with an overview of
the web-based Decision Support System (DSS) developed to facilitate its wide adoption. The DSS and procedure has been designed
and evaluated by managers as a useful tool, which facilitates and provides needed procedural guidance for protected area monitoring
whilst minimizing input requirements to do so. The procedure and DSS were developed following a review of existing protected
area assessment tools and a detailed primary investigation of the needs and capacity of its intended users. Essentially, the
procedure and DSS guides provide the facilities for protected area managers, in following a participatory approach to develop
a context-specific sustainability monitoring strategy, for their protected area. Consequently, the procedure is, by design,
participatory, context specific, holistic and relevant to protected area management and institutional procedures. The procedure
was piloted and formally evaluated in Greece, Italy, Turkey, Egypt, Malta and Cyprus. Feedback collected from the pilot evaluations
is also summarised herein. 相似文献
1000.
Deforestation is driven by a variety of factors, and has resulted in land use changes that threaten biodiversity, water and
energy resources. However, lack of reliable data and survey information in Nigeria has made the estimation of the effect of
deforestation difficult to establish. Consequently, the extent and rate of deforestation are less well known. The study therefore,
examined and analyzed the spatial and temporal patterns of deforestation over the period of 25 years (1978–2003); measured
the rates, trends and explained the factors that determined deforestation in Ijesa-Ekiti region of southwestern Nigeria. The
major sources of data for the study were satellites images. These were Landsat MSS 1978, with spatial resolution of 80 m,
SPOT XS 1986, SPOT XS 1994, with 20 m spatial resolution and NigeriaSat_1 2003, with 32 m spatial resolution. To make them
comparable, they were georeferenced to the same coordinates system, filtered, resampled and enhanced for visualization in
a GIS environment. Furthermore, Ilesa, Ijebu-Ijesa, Efon-Alaaye, Iloko-Ijesa, Erin-Oke and Erin-Ijesa were identified and
selected for ground truthing to validate the tonal values recorded in the images with the features on the ground. The result
of ground truthing was combined with visual image interpretation as training sites for supervised classification. Focus Group
Discussions were held with people who had lived in the area for over 20 years as a means of eliciting factors of deforestation
and the effects on forest biodiversity. The results indicated forest loss of 53,469.23 ha over the period of 25 years at an
annual deforestation rate of 7.21, 2.47, and 5.40% per year for 1978–1986, 1986–1994 and 1994–2003, respectively. FGDs with
various categories of people in the bigger towns confirmed deforestation in the area and were due to illegal lumbering, intensive
agricultural practices and growth of settlements resulted from increase in human population. FGDs also revealed extinction
of many forest species in their communities. In conclusion, the study advanced our understanding on techniques of analyzing
deforestation using geo-spatial technology. It also generated a synthesis of information on the rates of deforestation and
its driving forces, which are a complex mix of anthropogenic factors, the chief of which has been the conversion of forest
resources to agricultural land use. 相似文献
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