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排序方式: 共有267条查询结果,搜索用时 31 毫秒
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Clevan Lamason Bryce Macmillan Brigitte Leblon Zarin Pirouz 《Wood material science & engineering》2015,10(1):86-93
AbstractIn this study, water content in black spruce (Picea mariana Mill.) and aspen (Populus tremuloides Michx.) sapwood samples was investigated with time-domain magnetic resonance (MR). Time-domain MR measurements easily distinguish water in different environments in wood according to the spin-spin relaxation time and provide quantitative information on water content. The MR techniques employed can distinguish and quantify the individual signal components. Both black spruce and aspen have two signal components at moisture contents above the fiber saturation point. These two signal components correspond to motionally restricted water, often referred to as bound water, and unrestricted, or free water. Bound water content is constant above 40% moisture content. No signal from free water was detected at or below 20% moisture content in either species. We also demonstrate the use of a recently developed portable unilateral magnet that can be employed as a powerful tool in the study and measurement of water content in wood. 相似文献
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Diversity of the calabash tree (<Emphasis Type="Italic">Crescentia cujete</Emphasis> L.) in Colombia
Johanna Arango-Ulloa Adriana Bohorquez Myriam C. Duque Brigitte L. Maass 《Agroforestry Systems》2009,76(3):543-553
Germplasm of the calabash tree (Crescentia cujete L.) was collected in five major regions of Colombia, i.e. the Andes, Caribbean, Amazon, Orinoco, and Pacific regions. Collecting
this multipurpose tree was guided by the indigenous knowledge of farmers and artisans in each region. Large variation in fruit
shapes and sizes was found, of which some forms were typical for certain regions. Overall 56 accessions were collected and
roughly classified into 22 types by eight fruit shapes and eight sizes. Molecular markers (Amplified fragment length polymorphisms)
were applied to leaf tip tissue originating from vegetatively propagated plants in order to assess the diversity available
in the germplasm collected as well as to detect patterns of geographical or morphological similarity. One accession each of
C. alata H.B.&K. and C. amazonica Ducke were used as outgroups. Overall, genetic diversity was high (mean Nei and Li’s coefficient of 0.43). No relations could
be established between either geographical provenance or fruit morphology and patterns of genetic diversity. Concerning the
outgroups, the C. amazonica accession appeared to be a distinct species. The C. alata accession, however, did not seem to be sufficiently distinct from C. cujete to merit species status. The latter material may in fact be a hybrid or serve to challenge the validity of interspecific
organization of the genus Crescentia.
相似文献
Brigitte L. Maass (Corresponding author)Email: |
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The diatomaceous earth (DE) Dryacide® was tested under laboratory conditions on surfaces (2 g DE/m2) and in wheat grain (3 kg DE/t wheat) at a relative humidity of 70±5% and a temperature of 22±1°C. The wheat had a moisture content of 14.5%. The effect of surface treatments was tested onEphestia kuehniella, Oryzaephilus surinamensis, Tenebrio molitor andTribolium castaneum. The efficacy of grain treatments was determined usingEphestia elutella, O. surinamensis, Sitophilus granarius andTribolium confusum. In both treatments adult and larval stages were included.100% mortality were reached with the surface treatments in adults and larvae ofO. surinamensis and the adults ofT. molitor andE. kuehniella after an exposition time of 3–9 days. AgainstT. castaneum and the larvae ofT. molitor andE. kuehniella no complete control could be achieved.In the grain treatments the dosage of 3 kg DE/t wheat reached 100% mortality in all tested pests exceptS. granarius. Most sensitive wereO. surinamensis andE. elutella. InT. confusum the adults died within 13 days of treatment, but for complete control of the larvae 13 weeks were necessary. AgainstS. granarius the silica dust showed no satisfactory efficacy, because 49 days after beginning of the examinations beetles of the progeny hatched. Dryacide® could not prevent the reproduction of the granary weevil, but there was a lower number of progeny compared to the untreated control. 相似文献
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Monoglycerides are widely used in the baking industry because of their antistaling effects, mainly suppressing crumb firming. Commercial monoglycerides are normally prepared from hydrogenated fats, with stearate being the most common fatty acid. In a previous study, monoglycerides such as monopalmitate (C16) and monostearate (C18) had positive effects on Canadian short process bread but no improvements on sponge‐and‐dough process (SDP) bread. The objective of this study was to investigate the effects of saturated monoglycerides of varying fatty acid chain length (C14–C22) on SDP breadmaking quality by using volume judgment, crumb image analysis, and texture measurements. Higher levels (1.00–1.50%) of all monoglycerides (C14, C16, and C18) significantly (P < 0.05) increased loaf volume and cell diameter. The larger cell diameter with increasing levels of these monoglycerides may have resulted from softer, more extensible dough handling properties and greater gas cell stability during baking. Addition of C16 and C18 caused the largest increase in crumb softness with increasing monoglyceride levels but showed relatively low resilience, which might be related to larger loaf volume (i.e., lower density of bread). However, addition of blended monoglycerides C14+C16 increased crumb softness and loaf volume while partially retaining resilience. Each monoglyceride had a different function in breadmaking quality and somewhat positive effects on SDP. 相似文献
8.
Ameet Singh DVM DVSc Diplomate ACVS Brigitte A. Brisson DMV DVSc Diplomate ACVS Stephanie Nykamp DVM Diplomate ACVR 《Veterinary surgery : VS》2011,40(6):762-767
Objective: To (1) describe computed tomographic (CT) popliteal lymphangiography; (2) compare the number of thoracic duct (TD) branches detected by CT and by radiography after popliteal lymphangiography; and (3) to compare the number of branches detected after left and right popliteal lymphangiography. Study Design: Experimental study. Animals: Adult dogs (n=6). Methods: A randomly selected popliteal lymph node was percutaneously injected with 12 mL iodinated contrast medium through a 25‐g butterfly catheter over 4–5 minutes. Lateral and ventrodorsal (VD) thoracic radiograph projections and thoracic CT were performed. The procedure was repeated using the contralateral lymph node after a 48–72 hours washout period. Results: One dog had TD branches visible on CT but not on radiographs. A significantly greater number of TD branches were observed with CT popliteal lymphangiography compared with lateral and VD radiographic popliteal lymphangiography (P=.003 and P<.001, respectively). The number of visible TD branches observed between the 6th thoracic and 1st lumbar vertebrae were not significantly different in these dogs (P=.146). A significant difference in number of TD branches observed was not found after left or right popliteal lymph node injection (P=.097). Conclusions: CT popliteal lymphangiography consistently identified a greater number of TD branches when compared with radiographic popliteal lymphangiography. Injection of either popliteal lymph node resulted in the same number of TD branches being observed. 相似文献
9.
Joke Geets Brigitte Borremans Jaco Vangronsveld Ludo Diels Dani?l van der Lelie 《Journal of Soils and Sediments》2005,5(3):149-163
Background, Aims and Scope Sulfate-reducing bacteria (SRB) are known for their capacity to reduce and precipitate heavy metals (HM) as metal sulfides,
offering the opportunity to create an in situ reactive zone for the treatment of heavy metal-contaminated groundwater, a process
called in situ metal precipitation (ISMP). The applicability of the ISMP technology first has to be investigated at a laboratory
scale before going into an on site application. The evaluation and optimization of the ISMP process is facilitated when physical/chemical
analysis techniques are combined with molecular tools that specifically monitor the abundance, diversity and dynamics of the
indigenous sulfate reducing microbial community. In this study, batch experiments were conducted in order to investigate the
feasibility of ISMP as a groundwater remediation strategy for an industrial site contaminated with elevated levels of Zn,
Cd, Co and Ni.
Methods The potential of different types of carbon source/ electron donor (lactate, acetate, methanol, ethanol, Hydrogen Release
Compound?, molasses) to stimulate the sulfate reduction and metal precipitation activity of the naturally present (or indigenous)
SRB community was explored. In addition, the effect of amending vitamin B12 and yeast extract was evaluated. The ISMP process
was monitored by combining analytical analyzes of process parameters (SO42-concentration, heavy metal concentrations,
pH, Eh) with molecular tools such as SRB subgroup and genus specific PCR, denaturing gradient gel electrophoresis (DGGE),
and phylogenetic analysis of clone sequences, based on either the 16S rRNA or the dsr (dissimilatory sulfite reductase) gene.
Results and Discussion The efficiency of different carbon-sources to stimulate the ISMP process followed the order HRC 〉 molasses 〉 methanol
〉 lactate 〉 ethanol 〉 acetate. Within 10 weeks, the highest sulfate and metal removal efficiencies ranged from 85% to 99%.
Addition of yeast extract boosted the ISMP process, whereas vitamin B12 negligibly affected SRB activity. Analysis of the
sulfate reducing population by SRB subgroup and genus specific PCR demonstrated that members of the genus Desulfosporosinus
dominated in all batch tests, while 16S rDNA DGGE profiles additionally revealed the presence in the microbial communities
of non-sulfate reducing bacteria within the family Clostridium and the -proteobacteria. The dsrB-based DGGE profiles
allowed us to assess the diversity and dynamics of the sulfate reducing community and added to a better understanding of the
effects of different batch conditions on the ISMP process. Remarkably, all dsrB sequences affiliated with the dsrB gene sequence
cluster found in Desulfotomaculum, which received their xenologous dsrB gene from the -proteobacteria.
Conclusions The batch experiments, which aimed at stimulating the activities of the indigenous SRB communities, demonstrated that these
communities were present and that their activities could be used to obtain efficient in situ precipitation of the contaminating
heavy metals. This opens the possibility to test this concept in the future as an on site demonstration as part of the groundwater
strategy for the heavy metal contaminated site. Although batch setups are suitable for preliminary feasibility studies for
ISMP, they do not reflect the in situ situation where sulfate and heavy metal and metalloid polluted groundwater are supplied
continuously. A sulfate reducing strain JG32A was isolated from whose 16S rRNA gene affiliated with the genus Desulfosporosinus,
while its dsrB gene sequence clustered with Desulfotomaculum dsrB gene sequences, which received their xenologous dsr genes
from -proteobacteria. Therefore we hypothesize that the batch experiments enrich members of the Desulfosporosinus
genus that possess a non-orthologous dsrB gene.
Recommendation and Perspective The next step towards an on site pilot test for ISMP will be the setup of a series of column experiments, with process conditions
that are selected based on the above mentioned results. This will allow to define optimal ISMP process conditions and to test
its long-term efficacy and sustainability before going into an on site bioremediation application. By applying the described
molecular tools together with physical-chemical analyzes, it can be investigated whether the same SRB community is enriched
and which type of C-source is most effective in promoting and sustaining its growth and sulfate-reduction activity. 相似文献
10.
Pitre FE Pollet B Lafarguette F Cooke JE MacKay JJ Lapierre C 《Journal of agricultural and food chemistry》2007,55(25):10306-10314
The short-term influence of adequate and high nitrogen fertilization on poplar lignification was investigated. The high nitrogen supply decreased lignin staining in the newly formed secondary xylem, indicating that lignin deposition was affected. Acetyl bromide determinations gave a 9-10% decrease in lignin content; however, Klason lignin content was unchanged. Thioacidolysis showed that elevated N supply affected lignin structure such that there was a reduced frequency of lignin units involved in beta-O-4 bonds, a reduced syringyl/guaiacyl ratio, an increased frequency of p-hydroxyphenyl lignin units, more guaiacyl units with free phenolic groups, and more p-hydroxybenzoic acid ester-linked to poplar lignins. These features suggest that lignins from poplars grown under high N bear structural similarities to lignins formed during early stages of wood development. The findings also indicate that a gravitational stimulus inducing the formation of tension wood and high N availability lead to similar and additive effects on lignin content and structure. 相似文献