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排序方式: 共有87条查询结果,搜索用时 18 毫秒
71.
Marco Erni Pay Drechsel Hans-Peter Bader Ruth Scheidegger Christian Zurbruegg Rolf Kipfer 《Irrigation and Drainage Systems》2010,24(1-2):113-125
Due to poor urban sanitation farmers in and around most cities in developing countries face highly polluted surface water. While the sanitation challenge has obvious implications for environmental pollution and food safety it can also provide ‘free’ nutrients for irrigating farmers. To understand the related dimensions, a box-flow model was used to identify the most important water and nutrient flows for the Ghanaian city of Kumasi, a rapidly growing African city with significant irrigation in its direct vicinity. The analysis focused on nitrogen and phosphorus and was supplemented by a farm based nutrient balance assessment. Results show that the city constitutes a vast nutrient sink that releases considerable nutrients loads in its passing streams, contributing to the eutrophication of downstream waters. However, farmers have for various practical reasons little means and motivation in using this resource of nutrients. This might change under increasing fertilizer prices as the nutrient load will continue to increase by 40% till 2015 assuming a widening gap between population growth and investments in water supply on one side and investments in sanitation on the other. However, even a strong investment into flushing toilets would not reduce environmental pollution due to the dominance of on-site sanitation systems, but instead strongly increase water competition. Key options to reduce the nutrient load would be via optimized waste collection and investment in dry or low-flush toilets. The latter seems also appropriate for the city to meet the water and sanitation Millennium Development Goals (MDGs) without increasing water shortages in toilet connected households. 相似文献
72.
Thomas Müller Peter Thanei Wolfgang Mücke Hans-Peter Kriemler Tammo Winkler 《Pest management science》1999,55(5):594-596
The metabolism of cyprodinil, a novel broad-spectrum fungicide, was investigated in rats. After single oral administration of 0.5 or 100 mg kg−1 body weight, [phenyl-U-14C]cyprodinil was rapidly eliminated, principally in the urine. The metabolite pattern in urine exhibited a significant sex-related difference with respect to the major metabolite. Males and females both produced a dihydroxy metabolite, N-4-(hydroxyphenyl)-4-cyclopropyl-5-hydroxy-6-methylpyrimidin-2-ylamine. Female rats conjugated this metabolite with sulfate exclusively at the 5-hydroxypyrimidinyl moiety, while males formed equal amounts of the monosulfate and a disulfate conjugate. The sex dimorphism in the conjugation reaction indicates the involvement of a sex-specific sulfotransferase that catalyzed the transfer of the second sulfate group. 相似文献
73.
Armin Maier Johannes Müller Peter Schneider Hans-Peter Fiedler Ingrid Groth Francis S
K Tayman Friedrich Teltschik Christian Günther Gerhard Bringmann 《Pest management science》1999,55(7):733-739
Two fatty acids, (2E,4Z)-decadienoic acid and (2E,4Z,7Z)-decatrienoic acid, the latter being described for the first time as a natural product, were detected in the culture filtrate of Streptomyces viridochromogenes Tü 6105 by HPLC-diode array screening, purified by chromatographic methods and structurally elucidated by NMR techniques. Both metabolites show strong herbicidal activity against Lemna minor and Lepidium sativum. The herbicidal activities of the isolated compounds were compared with those of similar fatty acids and derivatives. © 1999 Society of Chemical Industry 相似文献
74.
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76.
Felix Spindler Benoit Pugin Hanspeter Buser Hans-Peter Jalett Ulrich Pittelkow Hans-Ulrich Blaser 《Pest management science》1998,54(3):302-304
The application of enantioselective catalytic methods for the technical preparation of chiral agrochemicals is illustrated for three active ingredients of the acylanilide type. The key step for the technical synthesis of the herbicide (S)-metolachlor is the enantioselective hydrogenation of an imine intermediate using a novel iridium ferrocenyldiphosphine catalyst with an unprecedented high activity and 80% ee. (R)-metalaxyl and (αS,3R)-clozylacon were synthesized via the enantioselective hydrogenation of corre-sponding enamide precursors with Rh and Ru/binap catalysts with >95% and 99% enantiomeric purity, respectively. © 1998 Society of Chemical Industry 相似文献
77.
When estimating heterosis it is often necessary to transform either the data or, within the context of generalized linear
models, the linear predictor, to satisfy certain assumptions. In this note it will be argued that the amount of heterosis
is scale-dependent varying with the kind of transformation. The same applies for the examination of dominance in quantitative
genetics. We exemplify the varying heterotic effect with phenotypic data of maize roots. Either a data transformation or a
generalized linear mixed model with appropriately chosen link function is applied to the data. It is concluded that care should
be exercised when transforming data in phenotypic as well as quantitative-genetic studies because partial dominance or heterosis
may be removed by a suitably chosen transformation. With data transformations, even overdominance or better parent heterosis
may disappear. When a data transformation is needed to meet the usual statistical assumptions such as normality and homogeneity
of variance, a back-transformation to the original scale may be necessary, depending on what is deemed the appropriate scale
for assessing genetic effects. 相似文献
78.
Karin Hartung Hans-Peter Piepho Helmut Knüpffer 《Genetic Resources and Crop Evolution》2006,53(4):737-751
Genebanks often characterize accessions based on evaluation trials. This paper evaluates geostatistical methods as a tool
to increase the utility of evaluation data. These methods were selected to overcome limitations resulting from a relative
lack of replication and the scarcity of standards or check varieties. The data employed in the present study comprise nine
characteristics of spring and winter barley, evaluated mostly as ratings. Ratings with quasi-metric scales were transformed
by using the folded exponential transformation. To estimate the genetic component of the total effect, we compared two methods:
Method 1 whereby a variogram is fitted by non-linear regression, and subsequently the implied spatial correlation is embedded
into a mixed model analysis, which estimates the genetic effect by Best Linear Unbiased Prediction (BLUP); and Method 2 where
each data value is re-estimated by kriging to correct for spatial effects and then the corrected data are submitted to a mixed
model analysis. For practical application we propose Method 1 (though occasionally we met convergence problems): Fit the short
range of the empirical variogram, visually choose the suitable covariance model. Use this and the initial values from non-linear
regression fit with the mixed model, fixing the spatial parts at their starting values from non-linear regression, and estimate
genetic effects by BLUP by using the fitted mixed model. To improve performance, we recommend that more standard or check
varieties be used and, wherever possible, replace rating scales with metric scales or free-percentage scales (without categories). 相似文献
79.
Hans Pretzsch Kamil Bielak Joachim Block Arkadiusz Bruchwald Jochen Dieler Hans-Peter Ehrhart Ulrich Kohnle Jürgen Nagel Hermann Spellmann Michał Zasada Andreas Zingg 《European Journal of Forest Research》2013,132(2):263-280
The mixture of beech (Fagus sylvatica L.) and oak (sessile oak, Quercus petraea (Matt.) Liebl., and pedunculate oak, Q. robur L.) is of considerable importance in Europe and will probably become even more important under climate change. Therefore, the performance of oak and beech in mixture was compared with the species’ growth in pure stands. Data from 37 long-term mixing experiments in Poland, Germany and Switzerland were pooled for analysis of mixing effects on stand productivity and possible interrelationships with mixing portions or site conditions. We found that on average, mixed stands of oak and beech exceeded biomass productivity in pure stands by 30 % or 1.7 t ha?1 year?1, as the growth of both species was benefitted by the mixture. However, that the interaction actually ranged from facilitation and overyielding on poor sites to underyielding on fertile sites triggered by competition. An empirically derived interaction model showed volume and dry mass growth changing in mixed stands from gains of 50 % to losses of 10 % depending on site conditions. It is concluded that the analysed mixture grows in accordance with the stress-gradient hypothesis and that our results suggest a site-specific relationship between species mixture and biomass productivity. As a consequence, an adequate species mix should result in increased productivity under steady state as well as climate change. 相似文献
80.
Ilatsia ED Roessler R Kahi AK Piepho HP Zárate V 《Tropical animal health and production》2012,44(3):519-530
The Sahiwal breed has been used for upgrading the East African Zebu (EAZ) for improved milk production and growth performance
in the southern rangelands of Kenya. Main users of this breed are Maasai pastoralists. Until now, there has been no deliberate
effort to understand why these pastoralists specifically prefer to keep Sahiwal genetic resources as well as which traits
are considered important by them and what is the underlying reason for this. However, this information is regarded vital for
further development of the breed. A survey was conducted between May and October 2009 among Maasai pastoralists in Kajiado
and Narok counties in the Southern part of Kenya, and private ranches and government farms to identify production objectives
and breeding goals of Sahiwal cattle producers. Sahiwal genetic resources were mainly kept for domestic milk production and
for revenue generation through milk sales and live animals. To a limited extent, they were kept for breeding and also for
multiple objectives that included insurance against risks and social functions. Production aims were influenced to varying
extents by various household and farmer characteristics. Sahiwal cattle and their crosses were generally perceived to be better
with respect to productive traits and fertility traits when compared to the EAZ. However, the EAZ was rated higher with respect
to adaptation traits. The breeding objective traits of primary importance were high milk yield and big body size, good reproductive
efficiency and relatively good adaptation to local production conditions. Performance and functional traits are important
breeding goals that play a major role in fulfilling the multiple production objectives. This forms the basis for the optimisation
of a breeding programme for sustainable utilisation to meet the needs of Sahiwal cattle producers. 相似文献