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41.
Sari?JuutinenEmail author Tuula?Larmola Rainer?Remus Edith?Mirus Wolfgang?Merbach Jouko?Silvola Jürgen?Augustin 《Biology and Fertility of Soils》2003,38(1):10-14
The contribution of Phragmites australis (Cav.) Trin. ex Steud. (common reed) litter as an origin of CH 4-C was studied in a microcosm experiment. 14C-labelled, dried and ground P. australis root and shoot litter was buried in waterlogged, planted or non-planted fen microcosms. The evolution of 14CO 2 and 14CH 4 from the pots was monitored during the 35-day experiment. The 14C activity in the shoots and roots of the plants, soil, and inundation water was also analysed at the end of the experiment. Up to 40% of the released CH 4-C originated from the added litter, whereas the rest originated from old soil organic matter. The comparison of planted and non-planted pots suggested that the contribution of recent plant-derived C (i.e. root exudates) to CH 4 emission was negligible. The proportion of litter-derived CH 4-C was significantly higher in the planted pots, suggesting that the presence of plants enhanced the formation of CH 4 from litter. The major part of the initial 14C activity was recovered from the soil. About 3% was recovered from the inundation water, about 10% was emitted as CO 2, and only <0.01% as CH 4. However, these results demonstrated that plant litter and old soil organic matter are the major sources of CH 4-C in fens during the early growth stage of P. australis. 相似文献
42.
Gold mining is the principal polluting activity in themunicipality of Poconé at the northern limit ofthe Pantanal of Mato Grosso, Brasil and ischaracterized by the inadequate use of mercury in thegold extraction process. A way to contribute to theassessment of the environmental impact of mercuryrelease in the Pantanal is to make use of bioaccumulation. Thus, determinations of total mercuryin 188 Gastropods of three different species were madein seven different sampling sites during the dry andwet periods. Increase of mercury levels in the snailswas restricted to the gold mining area and adjacentsedimentation areas. The largest mercuryconcentrations were found at the Tanque dos Padressite, reaching 2.04 g g-1 in individuals ofPomacea scalaris. In the other sampling sites,molluscs collected in the Araras/Piuval Bay complex,a mercury retention area, showed the largest mercuryconcentration, reaching up to 1.12 g g-1. 相似文献
43.
Ralf Berghofer Wolfgang Wilcke Vladimír Linke Otmar Nestroy Wolfgang Zech 《植物养料与土壤学杂志》1997,160(4):469-474
The objective of this study was to investigate changes of total concentrations and various extract-defined Al and heavy metal fractions in Slovak agricultural soils during the last 25 years. We compared 7 stored soil samples collected between 1966 and 1970 with samples collected in 1994 at the same sites. Seven fractions of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were determined with a sequential extraction procedure in all samples. Total concentrations of Cd, Zn, Mn, Ni, and Cu were lower in the 1994 samples; those of Al, Fe, Pb, and Cr were higher. Based on the initial concentrations, the average total concentration changes were: Cd(-10,3%)<Zn(-7,2%)<Mn(-4,8%)<Ni(-2,3%)<Cu(-1,4%)<Al(+2,1%)<Fe(+2,9%)<Cr(+7,4%)<Pb(+8,3%). This row is consistent with the decrease in metal mobility. The differences in salt-extractable metals showed the same pattern; however, changes were more pronounced than for total concentrations. The results suggest that decreases during the last 25 years are caused by higher leaching than deposition rates and increases vice versa. The highest increase in Cr and Pb concentrations is observed in the EDTA-extractable fraction, which mainly characterizes organically bound metals. 相似文献
44.
Extraction of PAH from Oh-horizon material after dispersion of air-dried samples in water resulted in a 80% higher yield of 20 PAH species compared to extraction of air-dried, freeze-dried or ground samples. Concurrently, the free surface area (BET method) of the organic matter increased. It was assumed that dispersion resulted in a disaggregation and/or stretching of organic aggregates, which makes interior aggregate regions available to the extractant that were pre-viously not accessible for the extractant due to diffusion barriers. 相似文献
45.
Wolfgang Ahlf Henner Hollert Helga Neumann-Hensel Mathias Ricking 《Journal of Soils and Sediments》2002,2(1):37-42
The recommendations presented in this paper use an integrated hierarchical approach combining toxicological, chemical and
ecological information to assess and evaluate the quality of sediments. For this reason, biological methods, in combination
with the tools of chemical analysis, are given priority when examining the quality of the sediment to establish adverse effects.
The trigger is the biotest, instead of chemical methods commonly used. The individual methods are presented for a German approach
and can be adopted to other countries by applying ISO, OECD methods. Support is provided on how to best integrate data generated
using different assessment tools. Keywords: Bioassays; biological and chemical analysis; ecotoxicology; integrated assessment;
sediment assessment; sediment quality; stepwise strategy 相似文献
46.
About the sorption of dissolved organic matter to forest soils This investigation characterizes the major forest soils of the temperate climatic zones (leptosols, vertisols, cambisols, luvisols, podzols, stagnosols, gleysols) as sorbents for dissolved organic matter (DOM). Sorption isotherms were obtained for 135 soil horizons from 36 profiles. When solutions containing no DOC were added, the release of dissolved organic carbon (DOC) was highest for horizons rich in organic C (A and Bh horizons). In subsoil horizons DOC release was much lower. Most of the investigated top soils (A and E horizons) and Bh, Bg, and C horizons showed a weak DOC sorption. This was caused by low contents of sorbents (clay and sesquioxides) and/or high contents of organic C. Organic C seems to reduce the DOC sorption by occupying binding sites. Subsoils rich in clay and sesquioxides like Bs, Bt, and Bw horizons showed a strong retention of DOC. Under the aerobic conditions of the experiments, some of the subsoils of stagnosols and gleysols also showed a strong sorption of DOC. However, in sorption experiments conducted after an anaerobic incubation, the DOC sorption decreased significantly. 相似文献
47.
48.
Abbas Rezaeizad Benjamin Wittkop Rod Snowdon Maen Hasan Valiollah Mohammadi Abbas Zali Wolfgang Friedt 《Euphytica》2011,177(3):335-342
Association mapping identifies quantitative trait loci (QTLs) by examining the marker-trait associations that can be attributed
to the strength of linkage disequilibrium between markers and functional polymorphisms across a set of diverse germplasm.
In this study, association mapping was performed to detect QTL-linked and genome wide SSR markers linked to phenolic compounds
of extraction meal in a population of 49 genetically diverse oilseed rape cultivars of dark-seeded, winter-type oilseed rape
accessions. Correction for population structure was performed using 559 genome wide SSR markers. Results showed that seed
colour is an important contributor to seed meal quality. Totally, 52 SSR markers linked to phenolic compounds were detected,
five of them being QTL linked markers. Some of these markers were already mapped on Brassica napus chromosomes that contain known QTL controlling oilseed rape meal quality traits. Our results demonstrate that association
mapping is a useful approach to complement and enhance previous QTL information for marker-assisted selection. 相似文献
49.
Aida Z. Kebede Baldev S. Dhillon Wolfgang Schipprack Jose L. Araus Marianne Bänziger Kassa Semagn Gregorio Alvarado Albrecht E. Melchinger 《Euphytica》2011,180(2):219-226
For in vivo production of doubled haploid (DH) lines in maize, the rate of haploid induction is of crucial importance. Maternal
haploid induction depends primarily on the inducer used as a pollinator. However, the source germplasm used as a maternal
parent and the environmental conditions for induction may also influence haploid induction and these aspects have not been
examined in tropical maize so far. The objectives of our study were to (i) monitor the variation for haploid induction rate
(HIR) among diverse source germplasm in tropical maize, (ii) determine the relative importance of general (GCA) and specific
(SCA) combining abilities for HIR, and (iii) investigate the influence of summer and winter seasons and genotype × season
interactions on this trait. Ten inbreds were mated in a half diallel design. The resulting 45 F1 single crosses were pollinated with the haploid inducer hybrid RWS × UH400 during the summer 2008 and winter 2009 seasons
in a lowland tropical environment in Mexico. HIR of the single crosses averaged over seasons ranged from 2.90 to 9.66% with
an overall mean of 6.74%. Mean HIR was significantly (P < 0.01) higher during the winter (7.37%) than summer season (6.11%). Significant (P < 0.01) variation was observed due to GCA effects of parental inbreds of single crosses but not for SCA, GCA × season and
SCA × season interactions. Our study underpins that a higher HIR in tropical maize can be obtained by selecting appropriate
source germplasm and undertaking pollination under favorable environmental conditions. 相似文献
50.
Almost universally, women with higher levels of education have fewer children. Better education is associated with lower mortality, better health, and different migration patterns. Hence, the global population outlook depends greatly on further progress in education, particularly of young women. By 2050, the highest and lowest education scenarios--assuming identical education-specific fertility rates--result in world population sizes of 8.9 and 10.0 billion, respectively. Better education also matters for human development, including health, economic growth, and democracy. Existing methods of multi-state demography can quantitatively integrate education into standard demographic analysis, thus adding the "quality" dimension. 相似文献