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91.
Minesoils are characterized by low soil organic matter and poor soil physicochemical environment. Mine soil reclamation process has potential to restore soil fertility and sequester carbon (C) over time. Soil organic C (SOC) pool and associated soil properties were determined for reclaimed minesoils under grass and forest landuses of varied establishment year. Three grassland sites of 30, 9, and 1 years after reclamation (G30, G9, and G1) and two forest sites, 11 years after reclamation (RF) and undisturbed stand of 40 years (UF), were selected within four counties (Morgan, Muskingum, Noble, and Coshocton) of southeastern Ohio. Soil bulk density (BD) of reclaimed forest (RF) soil was significantly higher than undisturbed forest (UF) soils within 10–40 cm soil depth profile. Reclamation process increased soil pH from slightly acidic to alkaline and decreased the soil EC in both landuses. Among grassland soils, significant changes in SOC and total soil N contents were observed within 0–10 cm soil depth. SOC contents of G30 (29.7 Mg ha−1) and G9 (29.5 Mg ha−1) were significantly higher than G1 soils (9.11 Mg ha−1). Soil N content was increased from G1 (0.95 Mg ha−1) to G9 (2.00 Mg ha−1) site and then the highest value was found under G30 (3.25 Mg ha−1) site within 0–10 cm soil depth. UF soils had significantly higher SOC and total N content than RF soils at 0–10 and 10–20 cm soil depths. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
92.
Lal R  Pimentel D 《Science (New York, N.Y.)》2008,319(5866):1040-2; author reply 1040-2
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93.
A one-step, three-component aqueous etchant was developed for revealing the tracks of charged particles in olivine. The etchant reveals tracks of small cone angle, which are equally well developed in all the crystallographic directions. The scope of fossil cosmic-ray track studies in extraterrestrial samples has thus been increased, because olivine is often an abundant constituent and because it has a higher threshold ionization for track registration and has lower uranium, thorium, and trace element concentrations as compared with pyroxenes and feldspars. The etchant does not attack any of the principal rock-forming minerals in normal etching time, which allows a nondestructive study of fossil tracks in thin-section mounts. The study of fossil cosmic-ray tracks in olivine is particularly valuable for investigations of very, very heavy cosmic-ray nuclei and for highly irradiated samples such as those found in the lunar regolith.  相似文献   
94.
Phytosociological parameters, soil and temperature conditions, importance values of species, life form, leaf size, and biomass were investigated at the village Tabai during autumn 2006. There was very little difference in air and soil temperature due to similar elevation. There was a great difference in biomass production for various stands. The original vegetation structure has been altered due to deforestation and overgrazing. There is a need for restoration of the habitat.  相似文献   
95.
Calcareous particles present in Pacific waters at depths of 50 to 3500 meters were collected by filtering seawater through spongin matrix. The specific activity of carbon-14 could be measured in two of these collections from depths of 2300 and 3500 meters. The ratios of carbon-14 to carbon-12 correspond to values observed in surface waters in recent years as a result of the addition of manmade carbon-14, thus indicating that the calcareous particles resulted from recent biological productivity. The results are related to the mean settling rates and the sizes and dissolution rates of biogenic calcareous particles in transit through a seawater column.  相似文献   
96.
R. Lal 《Geoderma》1983,31(3):185-193
The effects of 5, 10, 15 and 20 m slope lengths were investigated on runoff for natural slope gradients of about 1, 5, 10 and 15%. These studies were conducted on field runoff plots on natural slopes and under natural rainfall conditions at Ibadan in western Nigeria. The runoff, based on individual rainfall events, was not significantly correlated with either of three erosivity indices (EI30, KE > 1, AIm) and only a maximum of 36% of variability in runoff could be attributed to rainfall erosivity. Runoff per unit area decreased with increase in slope length. The mean annual runoff was of the order of 100, 87, 80 and 69 for 1977 and 100, 66, 49 and 35 for 1978 for 5, 10, 15 and 20 m slope lengths, respectively. Regression analyses indicated that the annual runoff was related to slope length according to the regression equation W = 773 L?0?53, where W is annual runoff in mm and L is slope length in meters. When fitted to data from all plots on a given slope steepness, for individual years the numerical value of length exponent b ranged from 0.153 to ?0.865.  相似文献   
97.
Mass selection was trialed on Fijian hybrid tilapia (Oreochromis niloticus × Oreochromis mossambicus) to reduce the amount of black spots on otherwise red phenotypes. The responses of two selection intensities (low‐selection line, top 50% – L) and (high‐selection line, top 30% – H) were compared with that of a control line (no selection – C) across three generations. The relative growth performance of treatments (C, L and H) was examined in parallel in each generation to assess whether mass selection had a correlated negative effect on growth performance. The results show clearly that red phenotype can be improved significantly by applying mass selection, without affecting growth performance. We propose that black spots on an otherwise red phenotype could represent the allelic products of a second genetic locus influencing skin colour, which can be expressed in red individuals (genotype Rr) but which may be masked in black individuals (genotype rr).  相似文献   
98.
The Common Fisheries Policy (CFP) reform sets out a move to a land‐all catch policy in European Union waters with a requirement for full reporting of fishing and on‐board processing activity. We explore the merits, stakeholder perceptions and applicability of different technology and approaches to the full documentation of fisheries that might be considered in the context of implementing the CFP reform. While recent efforts have focused on demonstrating how remote electronic monitoring (REM) systems can be utilized in fully documented fisheries (FDF), other technologies and approaches such as reference fleet and self‐sampling exist that could contribute to delivering FDF. Perceptions of fishers show that they would prefer using a reference fleet or self‐sampling to REM systems as a future method of implementing FDF. In general, there is support from the fishing industry for data collection and enhancement, but there remains some mistrust concerning the use of the data. Findings show that the most appropriate means and methods of FDF will depend on the circumstances and objectives for full documentation whether in enforcing a discard ban, documentation of total catch or data enhancement. We conclude that any technology or approach that will be used to deliver the monitoring requirements for FDF needs to make practical and commercial sense at the fishing vessel level.  相似文献   
99.
100.
Gynoecious is an important economic trait of cucumber for determinant of earliness and yield, yet genetic mechanism is not well understood for this trait. The experiment was conducted using F2 mapping population by crossing of PPC-2, a gynoecious and parthenocarpic line with Pusa Uday (monoecious and non-parthenocarpic cultivar). Out of 179 SSR markers screened, 39 markers differentiated the gynoecious and monoecious parents. However, only 17 markers were segregating with F2 mapping population, those were used for genotyping and linkage map analysis and these markers were placed along with F locus on chromosome 6 covering a total distance of 100.4cM. The SSR markers, SSR13251 and UW020605 were found to be closely linked to gynoecious (F) locus at 1.0 and 4.5 cM, respectively. The segregation of F2 population of PPC-2 × Pusa Uday and GPC-1 × Punjab Naveen and test crosses for sex type herein suggested that single dominant gene controlled the gynoecious sex expression in cucumber particularly in gynoecious genotypes PPC-2 and GPC-1. Therefore, the monogenic dominant nature of gynoecious sex identified in the present experiment and SSR markers closely linked to the F locus will be useful in marker-assisted backcross breeding for transfering gynoecious trait into horticulturally desirable varieties.  相似文献   
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