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251.
The sorption of phosphate by underwater soils rich in carbonate The phosphate sorption isotherms for carbonate rich under water soils (Unterwasserboden) can frequently be linearized by a modified Freundlich-isotherm when one assumes that, because of previously sorbed phosphate, the concentration of the equilibrium soil solution, P1,0 is greater than 0. However, in many cases, the character of the phosphate sorption can be adequately determined with only one phosphate addition (Ps,500). Both methods show that for dried samples from under water soils, the samples from reduced horizons have a higher P sorption than for the associated oxidized horizons. This can be explained by the presence of very sorption active ferrihydrite which has precipitated from previously biologically reduced material.  相似文献   
252.
Trace elements in pedosequences I. Two Braunerde-Podsol-sequences on slate Total amounts and fractions of Fe, Cu, Zn, Pb, Cd, Co and Ni extractable in boiling oxalate (replacing dithionite for analytical reasons), oxalate at room temperature and EDTA were determined in two pedosequences on slates ranging between Braunerde (Ochrept) and Podsol (Spodosol). The total amounts lay within the normal range of these elements in slates except a few samples much higher in Zn and Cd due to sulphides in the rock. In surface soil horizons rich in organic carbon the trace elements are accumulated in the order Cu < Zn < Cd < Pb. This accumulation increased with increasing degree of podsolization but is also partly due to atmospheric input. The relative accumulation of the various fractions in the surface soil increased in the order: boiling oxalate < room temperature oxalate < EDTA. Along the same order the depth function is determined to increasing extent by pedogenic processes rather than by lithogenic differences. In contrast to Fe, no minima in the podsol A2 nor definite maxima in the B were noticed for Cu, Zn, Pb and Cd. With regard to the affinity towards organic matter Cd appears to behave more similarly to Pb than to Zn. Co and, even more so, Ni were lost during podsolization. The significance of the fractionation procedure which was very useful with Fe was not satisfying with the trace elements. Relationships between single element fractions and various soil components were generally poor except for that between the EDTA fraction and organic matter content. The total element balance is complicated by the heterogenity of the parent rock, but an increase in the mobile fractions in the solum during podsolization is generally indicated. There was a loss in the total amount of Fe, Cu, Zn, Co and Ni due to podsolization whereas a gain for Pb and Cd was noticed most probably through atmospheric intake.  相似文献   
253.
254.
The dehydrogenase activity in recent underwater soils The figures for present dehydrogenase activity (DHA) in recent carbonaceous underwater soils of small rivers usually are below those of neutral arable soils with a good nutrient status. No dependence was found between DHA and organic matter or nutrient contents. The amount of formazan formed by chemical reduction of triphenyl tetrazolium chloride (TTC), becomes more important with increasing depth, whereas DHA shows no distinct depth function.  相似文献   
255.
Quantitative determination of reduced substances in subhydric soils The determination of reduced substances is possible by rapid oxidation with a diluted potassium dichromate/sulfuric acid solution at room temperature, and subsequent titration with FeSO4 solution. These values (meq/100 ml of fresh sample) show a nonlinear, negative correlation with redox potential, and increase with increasing content of organic material. Sulfides, expressed as FeS, amount to appr. 50 % of the reduction equivalents. Subhydric soils rich in nutrients show an increasing amount of reduced substances with increasing depth, whereas oligotrophic and mesotrophic soils give no distinct depth function.  相似文献   
256.
Biological reserves are intended to protect species, communities, and ecosystems in human-dominated landscapes. However, existing protected areas represent only relatively small, geographically biased samples of species and habitats. Climate change and habitat loss can exacerbate these biases and the net result is a small, skewed subset of historic environmental conditions. We developed a general model to improve the representation of environmental conditions across the range of at-risk species or any other elements targeted for conservation. We implemented the model as an integer linear-programming problem to select additional areas to complement existing reserves and create new portfolios that are bioclimatically representative across a range of climatic scenarios. We demonstrated the use of the model for a small dataset including two hydrologic variables across the range of five species of fairy shrimp (Anostraca) in the Central Valley ecoregion of California, USA under three climate scenarios. The bioclimatic representation model identified solutions that meet biodiversity representation goals and substantially improve bioclimatic representation at minimal additional cost in terms of total land selected for a conservation portfolio. Additional constraints rewarding bioclimatic representation under two conflicting climate scenarios resulted in only a small decrease in the performance of solutions with respect to current climate. We conclude that this model provides a general tool for improving bioclimatic representation, and results from the Central Valley case study suggest an encouraging, testable hypothesis that climatically robust bioclimatic representation can be achieved at negligible marginal costs.  相似文献   
257.
In 2008 and 2009, two consecutive outbreaks of Q fever in humans were recorded in the district of Freudenstadt, northern Black Forrest, Baden-Württemberg, Germany. In 2008, a total of 41 persons from a single local community fell ill and were found infected with Coxiella burnetii. Although comprehensive diagnostic and epidemiological outbreak investigations were conducted and control measures taken which included vaccination of ruminants at risk in three parts of the affected community, re-occurrence of the disease in 2009 with further 29 confirmed human Q fever cases could not be prevented. While the origin of infection of the first outbreak was probably a flock of 550 sheep moved in the surrounding of the affected villages, the source of infection for the consecutive outbreak in 2009 could not be identified. It seems possible that meadows contaminated with infectious placenta or birth fluids represented the sources of infection.  相似文献   
258.
Excess PO 4 3? from agricultural subsurface drainage and runoff degrades the overall water quality of the receiving surface waters in a cumulatively damaging process known as eutrophication. In the past 25 years, PO 4 3? removal by industrial byproducts and minerals has received considerable attention because these materials are both abundant and inexpensive. In this study, the saturated falling-head hydraulic conductivity and phosphate removal capability of granulated blast furnace slag (GBFS), cement kiln dust (CKD), zeolite, silica sand, and coconut shell activated carbon (CS-AC) were assessed. GBFS, zeolite, silica sand, CS-AC, and 5:95% and 10:90% CKD/sand blends all exhibited hydraulic conductivities ??0.001 cm/s. GBFS and the CKD/sand blends exhibited >98% PO 4 3? removal while CS-AC removed 70?C79% of initial PO 4 3? concentrations. In contrast, silica sand and zeolite removed 21?C58% of PO 4 3? . The phosphate removal data for each material was modeled against the Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, and Frumkin sorption isotherms to yield insight into possible removal mechanisms. Overall, GBFS, CKD, zeolite, silica sand, and CS-AC were sufficiently permeable and removed significant amounts of PO 4 3? and should be considered for use in treatment of agricultural effluent.  相似文献   
259.
In response to ongoing local extinction of species and the current biodiversity crisis, the number of reintroduction programs aiming to establish new populations of rare species in the wild has increased. However, only a small proportion of these programs has been planned and monitored scientifically and comparative multi-species studies are missing in this context. Therefore, the relative importance of factors involved in reintroduction success is poorly known. In 2007, we assessed population growth since introduction as a measure of establishment success of 25 wetland species (rare or extinct in the wild nationwide) and a total of 50 populations in Switzerland that had been introduced at seven restored sites with apparently adequate environmental conditions between 1997 and 2005. We related establishment success to 32 life-history traits of these species obtained from the BiolFlor database, to initial number of introduced plants (propagule pressure with 1–130 individuals introduced per population), and to the ecological distance between source sites and restored sites based on vegetation records. Our results clearly showed the importance of close ecological similarity between source and introduction sites for successful establishment of wetland species into restored pond habitats. In contrast, neither life-history traits nor propagule pressure were related to establishment success in our study. Based on our results, we strongly recommend enforcing ecological studies prior to reintroduction to accurately assess the suitability of restored sites. To unambiguously assess the key determinants of successful establishment, future reintroduction programs should be set-up according to experimental designs.  相似文献   
260.
An 8-year-old gelding with a 3-month history of anorexia and weight loss was found to have a massive subcapsular splenic hematoma. At flank laparotomy, 36 L of fluid was removed from the hematoma. The horse's condition improved after drainage. Fifteen months later, the horse became depressed and febrile. A splenic abscess containing Bacteroides ruminicola and Clostridium sporogenes was found at necropsy.  相似文献   
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