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991.
992.
At least 10% of the wetlands in Mexico are situated in the State of Veracruz on the central Gulf coast. The region has been intensively used for agriculture by humans for the last thousand years and today pastureland for cattle ranching is the dominant element of the landscape. We present a study of the wetland vegetation in a series of representative and internationally significant freshwater wetlands near the coastal lagoon La Mancha in Veracruz State. We obtained eleven wetland types formed by three wetland communities dominated by trees (mangrove or swamps), eight dominated by herbaceous species which we classified as marsh, five of which were native emergent marsh, one was a non-native emergent marsh and two were floating-leaved marsh. The highest diversity values were found in the Annona swamp, followed by the Sagittaria marsh and the Rhizophora–Laguncularia–Avicennia mangrove. CCA ordination showed that water level, disturbance and species number were the major factors explaining variation along axis 1, and on axis 2 conductivity, salinity, and bulk density. Wetland size was a major factor in both axes. We examined the interplay of intrinsic and extrinsic factors that give rise to the nature and diversity of wetland types that characterize the important wetland landscapes in this part of Mexico, being disturbance by human activities an important factor that favors the appearance of diverse species combinations.  相似文献   
993.
Identification of potential restoration areas is significant and important for implementing a sustainable restoration project and maintaining the ecosystem integrity. We established an eco-hydrological approach to identify potential restoration areas of freshwater wetlands that should and can be restored. Our eco-hydrological method identifies potential restoration areas from three dimensions, namely, transverse, longitudinal and vertical directions. Based on transfer matrix analysis between freshwater wetland and other land cover types and bird habitat suitability assessment, we identified the areas that should be restored under the 1989 and 2000 goals were 36,112 ha and 37,230 ha, respectively. Based on hydrological connectivity and balance between ecological water supply (EWS) and ecological water requirements (EWRs), the area can be restored under the 1989 and 2000 goals were 31,165 ha and 33,963 ha, respectively. The approach and results of this study can help in future restoration efforts in the Yellow River Delta and other similar coastal wetlands.  相似文献   
994.
Rangelands are among the most extensive anthropogenic landscapes on earth, supporting nearly 500 million people. Disagreements over the extent and severity of rangeland degradation affect pastoralist livelihoods, especially when impacts of drought and over-grazing are confounded. While vegetation indices (such as NDVI, or Normalized Difference Vegetation Index) derived from remotely sensed imagery are often used to monitor rangelands, their strategic integration with local ecological knowledge (LEK) is under-appreciated. Here, we explore these complementary approaches in Kyrgyzstan’s pasture-rich province of Naryn, where disagreements regarding pasture degradation could greatly benefit from additional information. We examine a time series of MODIS satellite imagery (2000–2015) to characterize browning trends in vegetation as well as to distinguish between climate- and grazing-induced trends. We also compare and contrast measured trends with LEK perceptions of pasture degradation. To do so, we first examine statistical trends in NDVI as well as in NDVI residuals after de-trending with meteorological data. Second, we use participatory mapping to identify areas local pasture managers believe are overgrazed, a particularly useful approach in lieu of reliable historical stocking rates for livestock in this region. Lastly, we compare the strengths and weaknesses of LEK and remote sensing for landscape monitoring.Browning trends were widespread as declining trends in NDVI (and NDVI residuals) covered 24% (and 9%) of the landscape, respectively. Local managers’ perceptions of pasture degradation better reflected trends seen in NDVI than in climate-controlled NDVI residuals, suggesting patterns in the latter are less apparent to managers. Our approach demonstrated great potential for the integration of two inexpensive and effective methods of rangeland monitoring well-suited to the country’s needs. Despite limitations due to terrain, our approach was most successful within the semi-arid steppe where pasture degradation is believed to be most severe. In many parts of the world, sources of long-term spatially extensive data are rare or even non-existent. Thus, paired LEK and remote sensing can contribute to comprehensive and informative assessments of land degradation, especially where contentious management issues intersect with sparse data availability. LEK is a valuable source of complementary information to remote sensing and should be integrated more routinely and formally into landscape monitoring. To aid this endeavor, we synthesize advice for linking LEK and remote sensing across diverse landscape situations.  相似文献   
995.
J. S. Song 《Plant Ecology》1992,98(2):175-186
Previous classification systems of the subalpine coniferous forests, belonging to the class Vaccinio-Piceetea Br.-Bl. 1939, in northeastern Asia were reviewed based on phytosociological data of Korea and Japan. A new order, the Abieti nephrolepidis-Piceetalia jezoensis was proposed for the subalpine coniferous forests in the continental part of northeastern Asia. Its distribution range and subordinate vegetation units are as follows:Order Abieti nephrolepidis-Piceetalia jezoensis ordo nov.In Korea:Alliance Abieti nephrolepidis-Piceion jezoensis Song 1991Association Taxo-Pinetum pumilae Song et Nakanishi 1985Association Thujo-Abietetum nephrolepidis Song 1991Association Abieti koreanae-Piceetum jezoensis Song 1991Alliance Abietion koreanae Song 1991Association Saso-Abietetum koreanae Song et Nakanishi 1985Association Betulo saitoanae-Abietetum koreanae (Song et Nakanishi 1985) em. Song 1991In northeast China and Maritime Province of Siberia, U.S.S.R.: (one separate alliance level or the same alliance as Abieti nephrolepidis-Piceion jezoensis)Formation Abies nephrolepis form. (Wu 1980)Formation Picea jezoensis-Abies nephrolepis form. (Wu 1980)Generally the Abieti nephrolepidis-Piceetalia jezoensis develops under the dry and cool continental climate and on the monophylogenic Dark Brown Conifer Soil Group derived mostly from granite and granitic gneiss. The subalpine or subarctic coniferous forests in Hokkaido, Sakhalin and Southern Kuriles may also belong to the Abieti nephrolepidis-Piceetalia jezoensis because of their floristic composition and the historical relevance of plant geography. The subordinate vegetation units are as follows:Alliance Piceion jezoensis Suz.-Tok. ex Jinno et Suzuki 1973Association Piceo-Abietetum sachalinensis Ohba 1967Association Piceetum glehnii Suz.-Tok. ex Miyawaki 1988The Abieti veitchii-Piceetalia jezoensis hondoensis Miyawaki et al. 1968 seems to fit only to the subalpine coniferous forests of Honshu and Shikoku of the Japanese Archipelago.  相似文献   
996.
The effect of intensive human intervention, poor socio-economic conditions and little knowledge on mangrove ecology pose enormous challenges for mangrove restoration in Southeast Asia. We present a framework for tropical mangrove restoration. Our proposed restoration framework addresses the ecology, economy and social issues simultaneously by considering the causes of mangrove degradation. We provide a step by step guideline for its restoration. We argue that although, ecological issues are of prime importance, economic and social issues must be considered in the restoration plan in order for it to be successful. Since mangrove ecology is not adequately studied in this region, local ecological knowledge can be used to fill the baseline information gaps. Unwanted human disturbance can be minimized by encouraging community participation. This can be ensured and sustained by facilitating the livelihood of the coastal community. We translated the restoration paradigm into a readily available practical guideline for the executors of the plans. We provide an example of mangrove restoration project that is closely related to our proposed framework. We are optimistic that this framework has the potential for universal application with necessary adjustments.  相似文献   
997.
A desirable goal of nature management is to re-establish self-sustaining ecosystems that ensure the persistence of natural habitats and species without requiring active management. Such self-sustainability relies on functional species interactions; yet, species interactions are often overlooked in the conservation literature, and when designing species-specific management efforts. Some interactions may not be restored under general management (e.g. land protection), and may require additional specific management interventions. Interventions targeting these specific interactions fall in a gap between general and species-specific management, effectively bridging community- and population-level approaches to conservation management. We propose that managers should explicitly identify cases where active management of specific interaction partners is required to achieve population self-sustainability. In addition, they should ensure that general management interventions do not inadvertently conflict with naturally occurring interactions, potentially thwarting conservation targets. Interaction functionality may be restored by relying on native species and by identifying the spatial context in which interactions are most likely to re-establish, considering distributional range overlap of interaction partners, local variation in individual encounter rate or even spatial variation in the expected success rate (efficiency) of the focal interaction.  相似文献   
998.
Summary Invasive plants are regarded as a major threat to biodiversity worldwide. Yet, in some cases, invasive plants now perform important ecological functions. For example, fleshy‐fruited invasive plants provide food that supports indigenous frugivore populations. How can the disparate goals of conservation versus invasive weed control be managed? We suggest using the fruit characteristics of the invasive plant to select replacement indigenous plants that are functionally similar from the perspective of frugivores. These could provide replacement food resources at sites where plants with these characteristics are part of the goal plant community and where such plants would not otherwise regenerate. Replacement plants could also redirect seed dispersal processes to favour indigenous, rather than invasive, plant species. We investigated the utility of this approach by ranking all indigenous fleshy‐fruited plant species from a region using a simple model that scored species based upon measures of fruit phenology, morphology, conspicuousness and accessibility relative to a target invasive species, Lantana (Lantana camara). The model successfully produced high scores for indigenous plant species that were used by more of the frugivores of Lantana than a random selection of plants, suggesting that this approach warrants further investigation.  相似文献   
999.
The soil seed bank can be an important source for vegetation regeneration, and data on the similarity between aboveground vegetation and the seed bank can provide information about successional pathways after disturbances or land-use change. We conducted this study in natural grasslands in the subtropical highland region in southern Brazil. We evaluated the effect of silviculture on richness, density, and composition of the seed bank at former grassland sites converted to pine plantations 25 years ago. We worked at six grassland sites and three pine plantation sites and used the seedling emergence method. Seed bank density and richness in grasslands were lower than those reported in similar environments in other regions. Species richness and density varied considerably within each vegetation type; therefore, richness and density were not statistically significant, while composition varied among vegetation types. In terms of species, the pine plantation seed bank was a small subset of the grassland seed bank. Seeds of typical grassland species were missing in the pine plantation, but also had only low abundances in the grassland, and similarity of seed bank and vegetation were low (less than 20%). The low seed density found in this study, including in grasslands areas, indicates that regeneration of species from the soil seed bank likely is of a limited role for the maintenance of plant populations after disturbances in this system. Our data further suggest that natural regeneration after tree planting in grasslands is reduced due to seed limitation.  相似文献   
1000.
Hydrogenase restoration of Escherichia coli hydrogenase deficient mutant HK7, which carries a mutation at hyd B locus, was studied. Anaerobic growth of HK7 in the presence of iron chloride or vanadium chloride resulted in the restoration of hydrogen uptake activity of hydrogenase, but not hydrogen evolution activity. The growth of HK7 in the presence of nickel chloride restored total hydrogenase activity (hydrogen uptake and evolution) as Waugh and Boxer (1986) reported. Therefore, the leniency of HK7 hyd B product might permit the transportation and incorporation of iron chloride or vanadium chloride in hydrogenase, resulting in the alteration of hydrogenase activity.  相似文献   
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