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991.
In southern Taiwan, brooded larvae of Pocillopora damicornis and Seriatopora caliendrum are released year-round in synchrony with new moons, and each larval release occurs over multiple days. Using P. damicornis and S. caliendrum as a model system, we describe within-brood variation in larval phenotypes and test for release-day effects that influence larval performance in the pelagic phase. Research was conducted in 2010 using larvae from corals collected in June and July from Nanwan Bay (21°56.179??N, 120°44.85??E). In June, larval phenotypes of both species were characterized immediately following release, and their competency to settle assessed. In July, larvae of P. damicornis were collected on 3?days over the peak release period and incubated for 7?C11?days at 28.0?°C and 320???mol?quanta?m?2?s?1; their phenotypes and settlement competency were measured every 2?days. P. damicornis larvae released close to peak release were 1.6 times larger in size, contained twice the number of Symbiodinium larva?1, and were 44?% more likely to settle in the first 24?h than larvae released early in the brood. In addition, peak-release larvae respired at a lower rate than larvae released late in the brood. Similarly, S. caliendrum larvae released close to peak release were 1.4 times larger in size and were 33?% more likely to settle in the first 5?h than larvae released early in the brood. In July, P. damicornis larvae differed between early (2?days prior to peak), peak, and late (2?days after peak) release. Protein content of early-release larvae was lower than peak- and late-release larvae, and this difference persisted throughout the development. Further, release day affected the way larval respiration varied throughout development. By showing that brooded coral larvae differ between release days and display maternal effects influencing performance in the swimming phase, our results suggest that pocilloporid corals utilize bet-hedging to increase reproductive success. 相似文献
992.
Stable isotope ratios of a tropical marine predator: confounding effects of nutritional status during growth 总被引:1,自引:1,他引:0
Larisa Lee Cruz Rona A. R. McGill Simon J. Goodman Keith C. Hamer 《Marine Biology》2012,159(4):873-880
Stable isotope analysis of carbon and nitrogen is frequently used to study the diets and foraging ecology of marine predators.
However, isotopic values may also be affected by an individual’s nutritional status and associated physiological processes.
Here, we use C and N stable isotopes in blood and feathers of blue-footed booby chicks at the Galápagos Islands to examine
how isotopic values are related to body condition and growth rate, and to assess the consistency in the isotope ratios of
individuals during growth. Size dimorphism in blue-footed boobies provided an additional opportunity to examine how isotope
ratios differ between sexes in relation to body size and growth rate. There was no significant difference between sexes but
both C and N stable isotopes were significantly negatively related to the body condition of chicks. These data were consistent
with individual variation in physiological processes affecting fractionation, although we cannot rule out the possibility
that they were also influenced to some extent by population-level variation in the stable isotope ratios of prey fed to chicks,
for instance related to prey size, depth or lipid content. Our results highlight the need for methods that take proper account
of confounding physiological factors in isotopic studies of foraging ecology and diet. 相似文献
993.
Impacts of climate variability and human colonization on the vegetation of the Galápagos Islands 总被引:1,自引:0,他引:1
Restrepo A Colinvaux P Bush M Correa-Metrio A Conroy J Gardener MR Jaramillo P Steinitz-Kannan M Overpeck J 《Ecology》2012,93(8):1853-1866
A high-resolution (2-9 year sampling interval) fossil pollen record from the Galápagos Islands, which spans the last 2690 years, reveals considerable ecosystem stability. Vegetation changes associated with independently derived histories of El Ni?o Southern Oscillation variability provided evidence of shifts in the relative abundance of individual species rather than immigration or extinction. Droughts associated with the Medieval Climate Anomaly induced rapid ecological change that was followed by a reversion to the previous state. The paleoecological data suggested nonneutral responses to climatic forcing in this ecosystem prior to the period of human influence. Human impacts on the islands are evident in the record. A marked decline in long-term codominants of the pollen record, Alternanthera and Acalypha, produced a flora without modern analogue before 1930. Intensified animal husbandry after ca. 1930 may have induced the local extinction of Acalypha and Alternanthera. Reductions in populations of grazing animals in the 1970s and 1980s did not result in the return of the native flora, but in invasions by exotic species. After ca. 1970 the trajectory of habitat change accelerated, continuously moving the ecosystem away from the observed range of variability in the previous 2690 years toward a novel ecosystem. The last 40 years of the record also suggest unprecedented transport of lowland pollen to the uplands, consistent with intensified convection and warmer wet seasons. 相似文献
994.
995.
M.?C.?KrautzEmail author L.?R.?Castro M.?González J.?C.?Vera H.?E.?González 《Marine Biology》2012,159(2):303-317
In this study, we determined variations in ascorbic acid (AA) concentrations in the gonads and liver, and of the innate immune
response (lysozyme activity and antiprotease) in the plasma of Engraulis ringens (anchoveta) and Strangomera bentincki (common sardine) during their reproductive seasons of 2007 and 2008 in the central area of the Humboldt Current. During the
main spawning season in 2007, colder environmental conditions, higher phytoplankton biomasses, low dinoflagellate abundance
and the dominance of large copepods in winter-early spring and of small copepods in late spring contributed to explain higher
AA concentrations in anchoveta tissues. During the warmer year of 2008, lower phytoplankton biomasses, a notable increase
of dinoflagellate abundance and the dominance of small-size copepods in winter and of larger copepods in spring occurred along
with a drastic drop in AA concentrations in anchoveta tissues. These results contrasted with those in common sardine, a species
in which AA did not vary as much as in anchoveta. An inverse trend between AA concentration in the liver and the gonadosomatic
index suggested the AA utilization during gonadic maturation. Innate immune parameters were determined for the first time
in small pelagic fish and constitute a new baseline data to evaluate their natural response to environmental changes. Changes
in the distribution and abundance of edible taxa containing AA and edible for fish along with variations in AA in fish tissues
during their reproductive season could become good indicators of the overall fish physiological condition resulting from variations
in the trophic web structure. 相似文献
996.
Manuela Bartel Stefanie Hartmann Karola Lehmann Kai Postel Humberto Quesada Eva E. R. Philipp Katja Heilmann Burkhard Micheel Heiko Stuckas 《Marine Biology》2012,159(10):2195-2207
Sperm proteins of the marine sessile mussels of the Mytilus edulis species complex are models to investigate reproductive isolation and speciation. This study aimed at identifying sperm proteins and their corresponding genes. This was aided by the use of monoclonal antibodies that preferentially bind to yet unknown sperm molecules. By identifying their target molecules, this approach identified proteins with relevance to Mytilus sperm function. This procedure identified 16 proteins, for example, enkurin, laminin, porin and heat shock proteins. The potential use of these proteins as genetic markers to study reproductive isolation is exemplified by analysing the enkurin locus. Enkurin evolution is driven by purifying selection, the locus displays high levels of intraspecific variation and species-specific alleles group in distinct phylogenetic clusters. These findings characterize enkurin as informative candidate biomarker for analyses of clinal variation and differential introgression in hybrid zones, for example, to understand determinants of reproductive isolation in Baltic Mytilus populations. 相似文献
997.
Understanding physiological and environmental variables that initiate sexual maturity would provide fundamental information
on life history dynamics. The aim of this study was to test the usefulness of the common circumnuclear ring (CNR), an oocytic
structure similar to the Balbiani body, which appears just prior to oocyte development as a predictor of first maturation
in Atlantic herring (Clupea harengus). The relative roles of physiology (e.g. fat) and photoperiod as triggers of maturation were also investigated. Samples were
collected in May 2008 (72°26′–73°84′N/11°26′–18°40′E) and February 2009 (56°12′–59°45′N/00°25′–03°06′W). These data suggested
that thresholds in body size may influence the decision to mature. We also found that short days (winter solstice) may be
the photoperiod trigger for a first-decision window for both Norwegian spring-spawning (NSS) and North Sea autumn-spawning
(NSAS) herring. The second-decision window for NSAS herring maturation appears to be triggered by longer days (spring equinox),
while a decreasing rate of day lengthening may trigger NSS herring maturation. So, photoperiodic cycle is a key determinate
of the timing of maturation in Atlantic herring. 相似文献
998.
Shrimps are economically and ecologically very important, yet a lack of ageing techniques and hence unknown growth rates often
impairs analytical assessments and management. A new method for the determination of in situ growth rates of shrimps is presented,
based on dry weight condition. Since this index oscillates from low values directly after moult to highest values prior to
moult in constantly feeding shrimp, the lowest observed pre-moult condition followed by a moult was introduced as a reference
value to separate growing and starving individuals in field data. Experiments with Crangon crangon confirmed that (1) post-moult condition varies in a narrow physiologically optimal range, regardless of recent growth increments,
and (2) dry weight condition prior to moult is closely related to the subsequent length increment. The method was applied
to estimate growth increments from in situ dry weight condition data of C. crangon. The new method can easily be applied to other related species, since the required data can be obtained from very simple
short-term experiments. 相似文献
999.
Akshay A. Gowardhan Michael J. Brown Eric R. Pardyjak 《Environmental Fluid Mechanics》2010,10(3):311-328
This work describes and evaluates a pressure solver that has been incorporated into a fast response three-dimensional building-resolving
diagnostic wind modeling system. The solver computes the three-dimensional pressure field around buildings and on exterior
walls in terms of a coefficient of pressure by solving a simplified pressure Poisson equation (that neglects turbulence stresses
in the Navier-Stokes) for incompressible flow. The input to the solver is the three-dimensional mean wind field obtained from
a fast response empirical-diagnostic urban wind model. The present study is an evaluation of the pressure solver using wind-tunnel
data for flow normal to and at a 45° angle to an isolated cubical building. Results for the normal incident wind angle case
indicate that the model satisfactorily reproduces the general spatial patterns and the magnitude of the pressure difference
around much of the cube. Details of the flow field that are not satisfactorily predicted include the spatial distribution
of pressure on the roof and the lower half of the front side of the building and the magnitude along the sidewalls where pressures
are over predicted. The results for the 45° case show reasonable agreement between the model and experiments on the front
and the back walls, but over predict pressures on the leading edge of the rooftop. Regions with poor pressure predictions
appear to be a result of unsatisfactory mean wind modeling. 相似文献
1000.
Abstract: The utility of a species can be divided into its direct, indirect, and options values. In the marine environment, direct consumptive values predominate and often lead to overexploitation at the expense of significant options values derived through bioprospecting for natural products. We surveyed the waters of the Egyptian Red Sea coast (Gulf of Aqaba [north] and the Red Sea [south]) for species of sea cucumbers and analyzed extracts from species for a range of bioactivities with potential biomedical applications. All habitat types were surveyed within these regions. We found 22 species of sea cucumber of which two, Holothuria fuscogilva and Holothuria flavomaculata , were recorded in Egypt for the first time. Although none of the species identified were unique to the Gulf of Aqaba, 10 species were only found in the Red Sea sector. Bioassay results showed that although no species had antibacterial activity, most extracts exhibited activity against Candida and Leishmania but were most active against a LoVo mammalian carcinoma cell line. Our most significant finding was the intraspecific variation in bioactivity in individuals collected from different habitat types and sectors of the coast. This variation may reflect the effect of environment on secondary metabolite production or may indicate significant genetic diversity between populations within a species. Our results indicate a potentially significant options value to sea cucumbers through bioprospecting. Given the importance of economic development in countries such as Egypt and the perceived low conservation value of invertebrates such as sea cucumbers, the linking of these factors to conservation is vital for the maintenance and sustainable exploitation of these animals . 相似文献