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171.
Because ethical restrictions limit in vivo studies of the human hemato-lymphoid system, substitute human to small animal xenotransplantation models have been employed. Existing models, however, sustain only limited development and maintenance of human lymphoid cells and rarely produce immune responses. Here we show that intrahepatic injection of CD34+ human cord blood cells into conditioned newborn Rag2-/-gammac-/- mice leads to de novo development of B, T, and dendritic cells; formation of structured primary and secondary lymphoid organs; and production of functional immune responses. This provides a valuable model to study development and function of the human adaptive immune system in vivo.  相似文献   
172.
In striated muscle, the plasma membrane forms tubular invaginations (transverse tubules or T-tubules) that function in depolarization-contraction coupling. Caveolin-3 and amphiphysin were implicated in their biogenesis. Amphiphysin isoforms have a putative role in membrane deformation at endocytic sites. An isoform of amphiphysin 2 concentrated at T-tubules induced tubular plasma membrane invaginations when expressed in nonmuscle cells. This property required exon 10, a phosphoinositide-binding module. In developing myotubes, amphiphysin 2 and caveolin-3 segregated in tubular and vesicular portions of the T-tubule system, respectively. These findings support a role of the bilayer-deforming properties of amphiphysin at T-tubules and, more generally, a physiological role of amphiphysin in membrane deformation.  相似文献   
173.
Long-distance free-space distribution of quantum entanglement   总被引:1,自引:0,他引:1  
We demonstrate the distribution of quantum entanglement via optical free-space links to independent receivers separated by 600 m, with no line of sight between each other. A Bell inequality between those receivers is violated by more than four standard deviations, confirming the quality of the entanglement. This outdoor experiment represents a step toward satellite-based distributed quantum entanglement.  相似文献   
174.
Adaptive goal-directed behavior involves monitoring of ongoing actions and performance outcomes, and subsequent adjustments of behavior and learning. We evaluate new findings in cognitive neuroscience concerning cortical interactions that subserve the recruitment and implementation of such cognitive control. A review of primate and human studies, along with a meta-analysis of the human functional neuroimaging literature, suggest that the detection of unfavorable outcomes, response errors, response conflict, and decision uncertainty elicits largely overlapping clusters of activation foci in an extensive part of the posterior medial frontal cortex (pMFC). A direct link is delineated between activity in this area and subsequent adjustments in performance. Emerging evidence points to functional interactions between the pMFC and the lateral prefrontal cortex (LPFC), so that monitoring-related pMFC activity serves as a signal that engages regulatory processes in the LPFC to implement performance adjustments.  相似文献   
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Influences of some peat soil features on the capillary water supply In the Weiße Moor near Gifhorn the grassland suffered in summer 1972 from extreme drought (Fig. 2), on peat soil profiles with a thin top layer of medium decomposed high bog over layers of only slightly decomposed transition forms from bog to fen (Fig. 1). This transition peat form was marked by the nature of its pores (Fig. 1). It is supposed that this led to the considerable reduction of the unsaturated water flow (Fig. 3). By this the capillary water supply of the grassland from still largly saturated deeper peat layers (>30 cm) was limited.  相似文献   
178.
To help improve the use of models in science & policy analysis in Asia it is necessary to have a better understanding of model performance and uncertainties. Towards this goal an intercomparison exercise has been initiated as a collaborative study of scientists interested in long-range transport in East Asia. An overview of this study is presented in this paper. The study consists of a set of prescribed test calculations with carefully controlled experiments. Models used the same domain, emission inventory, model parameters, meteorological conditions, etc. Two periods (January and May 1993) were selected to reflect long-range transport conditions under two distinct seasons. During these periods measurements of sulfur concentrations and deposition were made throughout the study region using identical sampling and analysis protocols. The intercomparison activity consists of four tasks (Blind Test, Fixed Parameter Test, Source Receptor test, and Tuning Test). All participants were asked to do Task A, and as many of the other tasks as possible. To date seven different models have participated in this study. Results and key findings are presented.  相似文献   
179.
Primary particulate matter is emitted directly into the atmosphere from various anthropogenic and natural sources such as power plants (combustion of fossil fuels) or forest fires. Secondary particles are formed by transformation of SO2, NOx, NH3, and VOC in the atmosphere. They both contribute to ambient particulate matter concentrations, which may have adverse effects on human health. Health hazards are caused by small particulate size, high number of especially fine (< 2.5 µm) and ultra-fine (< 0.1 µm) particles and/or their chemical composition. As part of an integrated assessment model developed at IIASA, a module on primary particulate matter (PM) emissions has been added to the existing SO2, NOx, NH3 and VOC sections. The module considers so far primary emissions of total suspended particles (TSP), PM10 and PM2.5 from aggregated stationary and mobile sources. A primary PM emission database has been established. Country specific emission factors for stationary sources have been calculated within the module using the ash content of solid fuels.  相似文献   
180.
Management practices designed to increase carbon sequestration via perennial tree crops are potential tools to mitigate the consequences of climate change. Changes in orchard management could enable growers to meet eco-verification market demands for products with a low carbon footprint and potentially exploit the emerging business opportunity in carbon storage, while enhancing the delivery of ecosystem services that depend on soil carbon stocks. However, there is no standard methodology to verify any potential claims of carbon storage by perennial vine crops. We developed a robust methodology to quantify carbon storage in kiwifruit orchards. Soil carbon stocks (SCS) were determined in six depth increments to 1 m deep in two adjacent kiwifruit blocks, which had been established 10 (“young”) and 25 (“old”) years earlier. We used a space-for-time analysis. Our key results were the young and old kiwifruit block stored about 139 and 145 t C/ha to 1 m depth. Between 80–90 percent of the SCS were stored in the top 0.5 m, and 89–95 percent in the top 0.7 m; there was no significant difference between the SCS in row and alley to a depth of 0.5 m; a CV of 5–15 percent indicates that 4–10 cores are needed for 80 percent confidence in the estimated SCS; we recommend separating each core into the depths 0–0.1, 0.1–0.3, 0.3–0.5, and 0.5–1 m to allow the assessment of SCS dynamics; we detected a weak spatial pattern of the SCS only for the old kiwifruit block with a range of about 3 m. A sampling bay along a vine row should have a maximum length of 3 m. We then assessed SCS in more than sixty kiwifruit orchards throughout New Zealand. They stored on average 174.9 ± 3 t C ha?1 to 1 m depth. On average, 51 percent of the SCS down to 1 m depth were stored in the top 0.3 m, which is the standard depth according to the Kyoto protocol. About 72 percent of the SCS to 1 m depth were captured when increasing the sampling depth to 0.5 m. These results underscore the necessity to analyze SCS in an orchard to at least 0.5 m deep. Using the same methodology to 1 m deep, we determined SCS in two wine grape vineyards on shallow, stony alluvial soils. We found a difference between vineyard and adjacent pasture SCS of nearly 16 t/ha. As the vines are 25 years old, this equates to carbon sequestration rates of 640 kg ha?1 yr?1. Our results of the space-for-time analysis also showed that all sequestration had occurred below 0.5 m. Therefore, we decided to sample C to a greater depth. In a 30-year old kiwifruit orchard and an adjacent pasture, SCS was measured to 9 m deep. In the kiwifruit orchard, we found a sequestration rate of 6.3 tons of C per hectare per year greater than in the adjacent pasture that was the antecedent land use.  相似文献   
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