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71.
通过对宝鸡植物园的菖蒲、梭鱼草、芦苇等9种水生植物进行埋根段与单株繁殖试验,结果表明:菖蒲、梭鱼草、芦苇三种植物采用埋根段繁殖,方法简单,最高成活率可达100%;茭白、玉蝉花等六种植物采用单株带根、不带根繁殖,带根的成活率高于不带根的。 相似文献
72.
73.
J.L. Christiansen S.-E. Jacobsen 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(6):539-544
Abstract Sensitivity to photoperiod in quinoa (Chenopodium quinoa Willd.) was studied under controlled conditions to enhance crop adaptation to environments outside its centre of origin. Two varieties, a traditional variety from Bolivia (Real), which will not mature under Danish conditions, and an early maturing variety (Q52), developed for Danish climatic conditions, were used in this reciprocal transfer experiment. Plants were moved from a short daylength of 10 h (SD) to a long daylength of 18 h (LD) and vice versa at set intervals from sowing to 100 days after sowing (DAS). A reaction of LD in time to flowering was observed only in the Bolivian variety Real. Under SD both varieties flowered after 39 DAS. For Real the LD regime resulted in a moderate increase in time to flowering to 44 DAS. The non-sensitive, juvenile period in Real was estimated to be approximately 16 days. In Q52 a moderate increase in the number of leaves was formed on the main stem after flowering at LD, which indicates that some daylength sensitivity remains. The most striking difference occurred during seed filling, when going from SD to LD. In Q52 the time from the end of flowering to maturity increased from 39 to 52 days. Under SD, Real had a seed-filling period similar to Q52, but at LD Real remained with green leaves during seed filling. Hard seed was observed in the still green perigonium 57 days after end of flowering. At this moment re-shooting occurred from the inflorescence, and seed maturity was not reached at the termination of the experiment at 150 DAS. This study shows that flower induction is not a major problem for adaptation of quinoa to North European conditions but that a very strong, daylength sensitive, stay green reaction is the main cause of the late maturity of South American introductions. 相似文献
74.
The urban matrix was recently shown to be a mosaic of heterogeneous dispersal habitats. We conducted a playback experiment of mobbing calls to examine the probabilities of forest birds to cross a distance of 50 m over urban matrix with different land-cover types in an urban area. We treated the reciprocal of the crossing probabilities as a movement resistance for forest birds. We drew resistance surfaces based on the land-cover maps of urban Sapporo. We applied a circuit theory to examine the relative role of a detour route consisting of a riparian corridor and urban matrix for dispersing forest bird individuals from continuous forest to an isolated green space in the midst of an urban area. Our results showed that wood cover had the highest crossing probability, while open land (grassland and pavement) had the lowest probabilities. Buildings and water surface displayed an intermediate probability. Resistance surfaces and flow maps at 25- and 50-m resolutions were very similar and suggested that dispersing individuals are likely to use the intervening building areas that dominate the urban matrix rather than detour through riparian corridors. Our results showed the useful combination of experimental approaches and circuit theory, and the importance of the spatial configuration of corridors, as well as the composition and management of dispersal habitats, to landscape connectivity. 相似文献
75.
Summary By using 15 available mono/nullisomic lines of Sun II back ground, the Heterodera avenae resistance gene in Nelson (from Avena sativa CI 3444) and Panema (from A. sterilis I. 376) were located on monosome XV. Genes with smaller effects were located on monosomes VIII and X. The absence of these genes derived from Sun II would increase cyst production on plants lacking major resistance genes. 相似文献
76.
Effect of supplying P to a portion of the soybean root system on root growth and P uptake kinetics 1
Abstract Knowledge of the effect of supplying P to portions of the soybean (Glycine max L. Merr) root system on P influx kinetics and root growth is important in developing P fertilizer placement practices for efficient fertilizer use. The objective of this research was to determine the effect of restricting P supply to portions of the root system on plant P status, root growth, and P influx kinetics. Two solution experiments were conducted in a controlled climate chamber. Phosphorus influx kinetics were determined on 25‐day‐old soybean plants that had been grown with 100, 75, 50, 25, and 12.5% of their roots initially exposed to P. Phosphorus influx kinetics were also measured on 25‐day‐old plants that had been P‐starved for the last 1, 2, 4, and 6 days prior to the determining P influx kinetics in order to relate plant P status to P influx kinetics. Reducing the portion of the roots supplied with P reduced P uptake. This resulted in a reduction in plant P concentration and was related to a 3.41‐fold increase in maximum P influx measured on 25‐day‐old plants. Restricting the proportion of roots supplied with P had no significant effects on the Michaelis‐Menten constant or on the concentration in solution where net influx was zero. Root growth rate of the roots in the P containing solution was not significantly different from those in the ‐P solution. Phosphorus uptake was correlated with final root surface area exposed to P (r2 = 0.88??). Starving the plants for P reduced P concentration in the shoot and root and this resulted in as much as a 1.68‐fold increase in maximum influx. 相似文献
77.
A series of experiments was conducted over 96 h in 240-mm-deep soil microcosms, to assess the effect of the presence and distribution of sheep manure over the soil surface on the vertical and horizontal distribution of burrows and numbers of the earthworms Aporrectodea trapezoides and Microscolex dubius. Within some microcosms the dung was placed on half of the soil surface and this caused aggregation, with over two-thirds of the earthworms being found in the soil directly under the manure. The presence of surface-applied sheep manure caused both species to aggregate in the surface soil. In contrast, without manure, A. trapezoides was evenly distributed throughout the soil profile while M. dubius aggregated in the deeper soil. The pattern of burrow construction was also influenced by the presence of surface manure. In the absence of manure, burrows of both species were evenly distributed through the soil, but in the presence of surface manure M. dubius constructed proportionally more burrows close to the surface. Both species constructed approximately twice the burrow area in the absence than in the presence of surface manure. For both species the daily rate of burrow construction decreased over the experimental period. From these data we inferred that there was more widespread and active foraging behaviour in both species when organic food material was scarce. M. dubius differed from A. trapezoides in that it more strongly concentrated foraging activity in the vicinity of the manure food source. 相似文献
78.
峨山自古就是彝族聚居的地方,传承了众多的彝语地名,其命名与彝族所处自然环境、社会生活和历史文化密切相关,体现出明显的区域特征和民族特征,从中可以看到峨山彝族社会历史风貌、语言文化和多民族文化的交流与融合. 相似文献
79.
Traugott J. Scheytt Petra Mersmann Elzbieta Rejman-Rasinski Anja These 《Journal of Soils and Sediments》2007,7(2):75-84
Background, Aim and Scope
One of the first occurrences of pharmaceutically active compounds in groundwater was reported from the sewage irrigation farms
south of Berlin. At these sewage irrigation farms treated sewage effluent passed the soil and unsaturated zone before reaching
the aquifer. Clofibric acid was detected in pore water from soils of those sewage irrigation farms in concentrations between
65 ng/L and 1430 ng/L. The aim of this study was to investigate the transport behavior of regularly detected clofibric acid,
diclofenac, ibuprofen, and propyphenazone under conditions comparable to those at the sewage irrigation farms in a multiple
compound sand column laboratory experiment.
Materials and Methods
Sediment column experiments were conducted to study the transport of pharmaceuticals in the unsaturated zone. The migration
was measured in fine to medium grained sand and leaching solution containing 1 mg/L of pharmaceutically active compounds and
61 mg/L of the tracer lithium chloride (LiCl). For the analysis of the pharmaceutical compounds the water samples were adjusted
to a pH value of 2 and then extracted by solid-phase extraction (SPE). Before extraction, the samples were spiked with a surrogate
standard for analytical quality control. The sample extracts were analyzed by capillary gas chromatography-mass spectrometry
(GC-MS) with selected ion monitoring (SIM). Depending on the sample volume (100 to 200 mL) and the matrix, the limits of detection
were between 1 and 10 ng/L, and the limits of quantitation were between 5 and 25 ng/L. Analysis for calcium, magnesium and
lithium were carried out using a 'Trace Scan' ICP-AES from Thermo Jarrel Ash. Sodium, potassium, iron and manganese were analyzed
using a Philips PU 9400 flame AAS. Analysis of anions was performed on a Dionex ion chromatograph DX 120.
Results
At the sewage irrigation farms the average concentrations of clofibric acid in the unsaturated zone declined from higher values
near ground surface (480 ng/L) to lower values near the groundwater table (65 ng/L). From the pharmaceuticals analyzed only
clofibric acid, primidone and propyphenazone could be analyzed in the first (upper) aquifer at the sewage irrigation farms.
All other pharmaceuticals could neither be detected in the first aquifer nor in the deeper aquifers. Breakthrough curves from
soil column experiments revealed no transformation and no retardation for clofibric acid, whereas transformation of diclofenac
was so high (79%) that no retardation factor could be calculated. Ibuprofen was significantly transformed (37%), transformation
of propyphenazone (17%) was quite low and retardation (Rf = 2.05) was in the range of previously conducted column experiments.
Discussion
The results confirm previously conducted experiments with clofibric acid where this compound was identified as highly mobile
and persistent. The results that diclofenac and ibuprofen are significantly transformed where unexpected as other studies
exhibited much lower transformation under saturated conditions at least for diclofenac. However, lower pH values and higher
oxygen contents in the unsaturated zone compared to the aquifer may explain this observed high transformation of these compounds
at the column experiments.
Conclusions
We conclude that irrigation with sewage effluent containing the compounds used in our experiments will lead to an input into
groundwater of clofibric acid, whereas diclofenac and ibuprofen will most likely be transformed during the passage. Propyphenazone
will be retarded but will most likely occur in groundwater. These results from the column experiments coincide very well with
the occurrence of the pharmaceuticals clofibric acid, primidone, and propyphenazone in the first aquifer.
Recommendations and Perspective :
The results underline the need to study the sorption of pharmaceuticals on various materials. e.g. organic matter, surfaces
at pH values occurring in the unsaturated zone. Future field studies will also include the investigation of desorption behavior
in the unsaturated zone. 相似文献
80.
Long-term effects of farmyard manure and sewage sludge on some soil biochemical characteristics 总被引:2,自引:0,他引:2
A. Saviozzi A. Biasci R. Riffaldi R. Levi-Minzi 《Biology and Fertility of Soils》1999,30(1-2):100-106
Changes in some soil biochemical properties were investigated following repeated applications of aerobically digested sewage
sludge (SS) under field conditions over 12 years, and compared with those of an adjacent soil cultivated and amended with
5 t ha–1 year–1 (dry weight) farmyard manure (FYM) for at least 40 years, as well as with those of an adjacent uncultivated soil, in order
to ascertain changes in soil quality. A short-term aerobic incubation was used to determine the potential of the samples to
mineralize the organic C supplied. Results indicated that cultivation caused a reduction in total, humified and potentially
mineralizable organic C, total N, light-fraction (LF) C, total and water-soluble carbohydrates, phenolic compounds, cation-exchange
capacity (CEC), microbial biomass C, specific respiration, hydrolytic and urease activities, and an increase in the heavy
metal content. Total and water-soluble carbohydrates and phenolic compounds expressed as a percentage of total organic C (TOC)
were similar in the differently managed plots. Of the two amendments, FYM treatments showed higher amounts of TOC and N, LF-C,
total and water-soluble carbohydrates, phenolic substances, CEC, specific respiration of biomass, hydrolytic and urease activities,
similar amounts and characteristics of humified organic matter and lower concentrations of Cu, Zn and Cr. Both FYM and SS
were inadequate treatments for the restoration of soil organic matter lost as a consequence of cultivation.
Received: 20 October 1998 相似文献