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991.
992.
A study was conducted in strawberry to establish a relationship between shading, mineral nutrient of leaves and fruits with albinism incidence. Plants grown under shade produced albino fruits in higher proportion than those grown in open fields. Similarly, plants under shade produced smaller sized fruits and have lower fruit yield. Among cultivars, Etna had highest incidence of albinism (49.6%) and Sweet Charlie the lowest (14.4%). Dry matter content (%), concentration of five major nutrients, viz. N, P, K, Ca, Mg, S and N:Ca and K:Ca nutrient ratios did not differ significantly in the leaves of plants producing normal or albino fruits. However, in contrast, the concentration of K was notably higher (1.97 mg g−1 fresh tissue weight) and that of Ca was lower (0.098 mg g−1 fresh tissue weight) in albino fruits than normal ones. Consequently, the ratios of N:Ca (11.34) and K:Ca (20.08) were higher in albino fruits than normal ones. Cultivars also differed widely in respect to dry matter (%), mineral content and nutrient ratios. Thus, it appears that lower light intensity favours the development of albinism in strawberry, and it seems that calcium is not the basic cause of albinism, but increased vigour associated with overuse of N and K might be positively associated with it.  相似文献   
993.
994.
The development time, survivorship and reproduction ofTuberolachnus salignus (Gmelin) (Hemiptera: Aphididae) [Lachninae, Lachnini] were studied onSalix babylonica (weeping willow) andSalix matsudana (corkscrew willow) at five constant temperatures (17.5, 20, 22.5, 25 and 27.5°C). The development time of immature stages ofT. salignus ranged from 14.56 days at 17.5°C to 12.50 days at 25°C onS. babylonica, and 16.47 days at 20°C to 12.28 days at 25°C onS. matsudana. The total survivorship of immature stages ofT. salignus varied from 28% to 85% at 22.5 and 17.5°C, respectively, onS. babylonica, and from 13% to 63%, respectively, at 17.5 and 25°C onS. matsudana. The greatest intrinsic rate of increase occurred at 25°C onS. babylonica (0.2691) and also onS. matsudana (0.2607). The mean generation time of the aphid population ranged from 14.15 days at 25°C to 16.24 days at 17.5°C onS. babylonica, and from 14.33°C days at 25°C to 19.86 days at 20°C onS. matsudana. The optimal temperature forS. babylonica growth, development time, reproduction and percent survival was 25°C.  相似文献   
995.
Successful fruit set depends on several reproductive processes including pollen germination and tube growth processes. An experiment was conducted to determine the effects of temperature on pollen germination characteristics and to identify species/genotypic differences in Capsicum using the cumulative temperature response index (CTRI) concept. Pollen was collected from plants of seven genotypes from five Capsicum species, adapted to various parts of the world and grown outdoors in large pots. The pollen was subjected to in vitro temperatures ranging from 15 to 50 °C at 5 °C intervals. Pollen germination and tube lengths were recorded for all species after 24 h of incubation at the respective treatments. Species/genotypes differed significantly for in vitro pollen germination percentage and pollen tube length with mean values of 78% and 734 μm, respectively. The mean cardinal temperatures (Tmin, Topt, and Tmax) averaged over genotypes, were 15.2, 30.7, and 41.8 °C for pollen germination and 12.2, 31.2, and 40.4 °C for pollen tube growth. The CTRI of each species/genotype calculated as the sum of eight relative individual stress response values, such as maximum pollen germination, maximum pollen tube length; Tmin, Topt, and Tmax temperatures of pollen germination, and pollen tube lengths, identified species tolerance to high temperatures. Capsicum annum cv. Mex Serrano from Mexico was identified as tolerant, C. chacoense cv. 1312 and C. spp. cv. Cobanero from Argentina and Guatemala, respectively as intermediate and C. frutescens cv. Early Spring Giant from China, C. annum cv. Long Green from South Korea, C. spp. cv. NM89C130 and C. pubescens cv. 90002 from Guatemala as sensitive to high temperatures. The tolerant species/genotypes can be used in breeding programs to develop new genotypes that can withstand high temperature conditions both in the present climate and particularly in a future warmer climate.  相似文献   
996.
There is little available information on the effects of temperature and CO2 enrichment on stomata anatomical characteristics of plants. Effect of these two microclimates was studied on five rose (Rosa spp.) cultivars, viz. ‘First Red’ (used as check), ‘Arjun’, ‘Raktima’, ‘Raktagandha’ and ‘Pusa Pitamber’. Budded, single-stemmed rose cultivars having five lateral buds were grown in controlled environment growth cabinets under enriched CO2 (1000 μmol mol−1) and optimum (28/18 °C, T0) or high (35/25 °C, T1) temperature for 50 days. All observations were made on the abaxial leaf surface. Significant increases in stomatal density (68.7%), index (29.6%) and epidermal cell density (37.3%) were recorded in plants grown at high temperature over control with CO2 enrichment. The cultivars responded differently in terms of length and width of guard cell and stoma (pore) under high temperature, however, the values averaged over treatments showed a significant reduction in these parameters. Further, number of stomata per leaf was higher (28.3%) in plants grown at high temperature, except First Red. A reduction in mean leaf area (26.7%) and dry mass (32.0%) was recorded at high rather than optimum temperature. The specific leaf area was maximum in Arjun (87%) while in First Red, a 14% reduction was noted at high temperature.  相似文献   
997.
Land–water interactions were examined in three regions in the Virginian Biogeographic Province; the southern shore of Cape Cod, Massachusetts; the Hudson/Raritan region of New York; and the eastern shore of the Delmarva (Delaware/Maryland/Virginia) Peninsula. Cumulative distribution functions were used to evaluate similarity in environmental condition among estuaries. Spatial-setting variables (location in a river, coastal lagoon, or in open waters) were associated with variation for some measures of estuarine condition. Patterns of coastal urban and agriculture gradients were measured and their relationship with indicators of estuarine condition was modeled statistically. When estuaries were pooled, the highest variation explained by spatial-setting variables was found for dissolved oxygen (DO, R 2 = 0.44) and salinity (R 2 = 0.58), with DO decreasing in river locations and salinity decreasing with rainfall and sampling locations near rivers. The explanatory power for the other indicator variables was low and varied from 6% to 27%. Rainfall explained some of the variation (R 2 = 0.23) in total suspended solids. Moderate (0.4 < | r | < 0.7) to strong (| r | ≥ 0.7) linear associations were found between total urban area and measures of estuarine condition. Within regions, total urban area was positively associated with Silver (r = 0.59), Cadmium (r = 0.65), and Mercury (r = 0.47) in Cape Cod, and inversely related to DO (r = −0.65) in the Hudson/Raritan region. No associations were found in the Delmarva Peninsula study area. Total area of agriculture showed a moderate association with Arsenic in Cape Cod, but no other associations were found in the other two regions. Our analyses show a measurable impact of urban land use on coastal ecosystem condition over large areas of the northeastern United States. This pattern was most evident when many different landscapes were considered simultaneously. The relationship between urban development and estuarine condition were weaker within the individual regions studied. The use of land use/cover models for predicting estuarine condition is a challenging task that warrants enhancements in the type, quantity, and quality of data to improve our ability to discern relationships between anthropogenic activities on land and the condition of coastal environments.  相似文献   
998.
In this study, the genetic relatedness of 22 low chill requiring walnut genotypes adapted to the south east Mediterranean region of Turkey was analysed by amplified fragment length polymorphism (AFLP) markers. Relatively low level of genetic variation was detected among the genotypes examined by five AFLP primer combinations, suggesting that these walnut genotypes selected predominantly for their low chill requirement have relatively narrow genetic base. In addition, the geographical proximity of the genotypes analysed was not correlated with their level of genetic relatedness. These results have implications for walnut breeding and conservation.  相似文献   
999.
One-year old scale bulblets of Lilium longiflorum Thunb. ‘Nellie White’ (Easter lily) were grown for 107 days during growth period 1 (GP-1) in six growth chambers under constant day/night temperature regimes of 30/26, 26/22, 22/18, 18/14, 14/10 and 10/6 °C. Subsequently, half of the plants in each temperature regime were transferred to 18/14 °C and the other half continued at the six constant temperature regimes. Both groups of plants were grown for an additional 89 days in growth period 2 (GP-2). Continuous temperatures of 26/22, 26/22–22/18 and 26/22–18/14 °C produced the greatest increase in basal bulb fresh weight (the main planted bulb), basal bulb circumference and stem bulb fresh weight, respectively. However, shifting these optimal temperatures to 18/14 °C during GP-2 resulted in a lower increase in basal bulb fresh weight and circumference. The optimum range for stem bulb production was expanded to 30/26–14/10 °C by shifting to 18/14 °C. The greatest increase for basal root growth occurred at 14/10–10/6 °C and for stem root growth at 14/10 °C. The temperature shift did not affect either root type. Maximum increase for stem length was at 26/22 and 22/18 °C and for stem plus leaf weight at 14/10 °C under constant temperature regimes. Transferring the plants from 10/6 to 18/14 °C resulted in the greatest increase in stem length and from 10/6 and 14/10 to 18/14 °C in the greatest increase in stem plus leaf weight. The greatest increase in the number of leaves occurred at 26/22 and 10/6 °C, but this growth parameter was unaffected by shifting to 18/14 °C, indicating that leaf number was determined in GP-1. Bulbils developed only when bulbs at high GP-1 temperature regimes (30/26 and 26/22 °C) were transferred to 18/14 °C during GP-2. Lower temperatures tended to favor an increase in flower bud production under continuous temperature regimes, while shifting to 18/14 °C increased flower bud production after initially high and low temperatures. Meristem abortion was greatest at 30/26 °C followed by 26/22 °C, but was not affected by temperature shifts in GP- 2. Thus, it is concluded that the abortion was induced or initiated during GP-1.  相似文献   
1000.
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