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51.
Yoshio Kijidani Tetsuya Hamazuna Satoshi Ito Ryushi Kitahara Shinsuke Fukuchi Nobuya Mizoue Shigejiro Yoshida 《Journal of Wood Science》2010,56(1):1-6
The lumber from sugi plantations in Japan displays large intra- and intertree variation in mechanical properties, even within
a stand. These variations seem to be induced by the effects of the characteristics of cultivars as well as the effects of
growth traits on mechanical properties. Therefore, the effects of growth traits on mechanical properties per cultivar need
to be precisely examined. In this study, we focused on the effects of growth traits, especially height-to-diameter ratio (H/D
ratio), on stem stiffness per cultivar. Sixteen cultivars were classified into three groups according to the relationships
between stem stiffness and growth traits. In cultivars that showed a close correlation between growth traits and stem stiffness,
it was assumed that stem stiffness could be controlled to a certain extent by silvicultural practices using the H/D ratio
as an indicator. In cultivars that showed a weak correlation between growth traits and stem stiffness, selecting cultivars
for the production of logs with higher mechanical properties seemed to be effective; in this study, Kumotoshi, Tanoaka, and
Edanaga were found to be suitable. Tree age and site index may be important factors for producing wood with higher mechanical
properties. 相似文献
52.
A forest road network in northeastern Italy was explored by field investigations to evaluate the cost of covering annual demand
of woodchips according to three scenarios. The first scenario (A) considered the current extent of the forest road network
(mainly tractor road) and the associated qualitative characteristics; the second scenario (B) evaluated the possibility of
increasing the availability of the technical amount of forest biomass by extending the forest road network by three tractor
roads (3.9 km); the third scenario (C) considered the impact on woodchip supply of converting 9.3 km of tractor forest road
into truck forest road. At a woodchip price of 60 € t−1, the cost–supply curve of scenario C indicated a woodchip amount of 2886 t year−1, which was 561 t year−1 greater than scenario A and 161 t year−1 greater than scenario B. 相似文献
53.
The rapid expansion of the world’s urban population is a major driver of contemporary landscape change and ecosystem modification.
Urbanisation destroys, degrades and fragments native ecosystems, replacing them with a heterogeneous matrix of urban development,
parks, roads, and isolated remnant fragments of varying size and quality. This presents a major challenge for biodiversity
conservation within urban areas. To make spatially explicit decisions about urban biodiversity conservation actions, urban
planners and managers need to be able to separate the relative influence of landscape composition and configuration from patch
and local (site)-scale variables for a range of fauna species. We address this problem using a hierarchical landscape approach
for native, terrestrial reptiles and small mammals living in a fragmented semi-urban landscape of Brisbane, Australia. Generalised
linear modelling and hierarchical partitioning analysis were applied to quantify the relative influence of landscape composition
and configuration, patch size and shape, and local habitat composition and structure on the species’ richness of mammal and
reptile assemblages. Landscape structure (composition and configuration) and local-scale habitat structure variables were
found to be most important for influencing reptile and mammal assemblages, although the relative importance of specific variables
differed between reptile and mammal assemblages. These findings highlight the importance of considering landscape composition
and configuration in addition to local habitat elements when planning and/or managing for the conservation of native, terrestrial
fauna diversity in urban landscapes. 相似文献
54.
Effects of spatial habitat heterogeneity on habitat selection and annual fecundity for a migratory forest songbird 总被引:1,自引:1,他引:0
Understanding how spatial habitat patterns influence abundance and dynamics of animal populations is a primary goal in landscape
ecology. We used an information-theoretic approach to investigate the association between habitat patterns at multiple spatial
scales and demographic patterns for black-throated blue warblers (Dendroica caerulescens) at 20 study sites in west-central Vermont, USA from 2002 to 2005. Sites were characterized by: (1) territory-scale shrub
density, (2) patch-scale shrub density occurring within 25 ha of territories, and (3) landscape-scale habitat patterns occurring
within 5 km radius extents of territories. We considered multiple population parameters including abundance, age ratios, and
annual fecundity. Territory-scale shrub density was most important for determining abundance and age ratios, but landscape-scale
habitat structure strongly influenced reproductive output. Sites with higher territory-scale shrub density had higher abundance,
and were more likely to be occupied by older, more experienced individuals compared to sites with lower shrub density. However,
annual fecundity was higher on sites located in contiguously forested landscapes where shrub density was lower than the fragmented
sites. Further, effects of habitat pattern at one spatial scale depended on habitat conditions at different scales. For example,
abundance increased with increasing territory-scale shrub density, but this effect was much stronger in fragmented landscapes
than in contiguously forested landscapes. These results suggest that habitat pattern at different spatial scales affect demographic
parameters in different ways, and that effects of habitat patterns at one spatial scale depends on habitat conditions at other
scales. 相似文献
55.
Water interactions in polycarbonate films have been studied using fluorescence and NIR Fourier transform spectroscopy. During
water sorption process, the fluorescence emission spectra showed sensitive changes with the peak at 332 nm red shifted by
18 nm with water sorption. This red-shifted peak could be due to phenyl-2-phenoxybezoate, which is one of two major thermal
degradation products in polycarbonate. In the spectra of phenyl-2-phenoxybenzoate in dimethyl formamide solution, a progressive
red shift was also observed with the water addition. By using the NIR spectra, hydrogen-bonding interactions of the sorbed
water with polycarbonate were investigated. It was found that water can be analyzed as free water S0 or single hydrogen bonded water, S1 while double hydrogen bonded water was negligible. During water immersion, most water species which are present as S0 species decrease slightly, with a small increase in S1 species. During desorption, S0 species decrease sharply, while S1 species is reduced gradually. Two examples of S1 structure in water-sorbed polycarbonate are proposed. 相似文献
56.
Although high performance fibers possess higher thermal resistant properties, they show very low sunlight stability. In this paper, a new sol-gel treatment method was used to enhance their light-resistant properties. Their mechanical property retention ratios (tenacity, extension, modulus) of fibers treated with titanium hydrosol were higher than those of the original Kevlar®129, PBO, and Kermel® fibers after light irradiation. Moreover, Kermel® fiber showed the highest improvement among the three kinds of fibers. 相似文献
57.
This study develops a method to evaluate the contact coolness of fabric using the infrared thermal image of a small test specimen. By using infrared thermal images of 7 types of fabrics developed as cool fabric, the average temperature difference on the surface of the human palm and a heating plate, with and without fabric was measured and this was used for the scale of the ability of the fabric to cool by touch. By comparing the average temperature differences with the Qmax of a fabric, absorption coolness, subjective contact coolness, and correlations were investigated. More heat is transmitted via fabric when the Qmax value is higher and average temperature difference of thermogram image is smaller, which means the coolness perceived by the skin becomes stronger. Fabric with a small average temperature difference in infrared thermal imaging had a high Qmax value and it was evaluated as having strong coolness in subjective evaluation too. However, it was found that there was no relationship between average temperature differences and absorption coolness. Therefore, it can be concluded that the evaluation of fabrics’ coolness using infrared thermal image is useful when evaluating contact coolness at the point of physical contact. In addition, by comparing the methods using the palm and heating plate, the method using the palm showed higher correlation with Qmax (-.828, p<0.05). Therefore, we confirmed that evaluating the coolness of small test specimens using an infrared thermal camera and the palm is effective. 相似文献
58.
The warmth retention of down is improved through grafting DTAC (dodecyl trimethyl ammonium chloride) onto the natural fiber. The effect of DTAC concentration (A), temperature (B), and time (C) on the warmth retention was studied using the response surface method to obtain the optimal experimental formula and models. The optimum process conditions are A: 17.1 %, B: 38.91 °C, C: 61.37 min and the predicted warmth retention rate is 80.4 %. Verified by experiments, the actual result is 80.34 %, and the fitting degree is 99.92 %. The results show that the warmth retention rate of the treated down increased by 5.98 % compared to raw down. The filling power significantly increased by 21.85 %, and the graft modification had no effect on the turbidity of the down. No obvious changes were detected using SEM. This explains that the DTAC was successfully grafted onto the down fiber and the modification did not damage the down. 相似文献
59.
Tourmaline can enhance filtering efficiency to PM2.0 of microfiber warp-knitted mesh fabric. In this paper, microfiber warp-knitted mesh fabrics were designed with different mesh structures and mass fraction of tourmaline solution respectively. The effect of tourmaline concentration on filtering efficiency of fabrics was investigated. After the tourmaline solution, the strength of mesh fabrics and durability of tourmaline’s conglutination to the mesh fabrics were explored at the same time. The results shown that the filtering efficiency of microfiber warp-knitted mesh fabrics dealing with tourmaline was resentful. Breaking strength of fabrics decreases with increasing mass fraction of tourmaline solution. The resistant efficiency of fabrics and tourmaline adhesive on the mesh fabrics were still stable along with the increasing mass fraction of tourmaline. 相似文献
60.
Present study dealt with the fabrication of chitosan/zinc oxide nano-composites (CZNCs) using a facile preparation method. The structural features of nano-composites were investigated by using advanced analytical techniques. The developed nano-composites exhibited hexagonal structural pattern with an average particle size of about 51 nm. The developed CZNCs were dispersed in 2-propanol and applied on polyester by using the pad-dry-cure method. The treated fabric specimens were characterized for surface, functional and textile properties including antibacterial activity and (ultra violet) UV- blocking. The nano-composite treated polyester fabric exhibited durable antibacterial, UV- blocking and textile properties with fair whiteness index. 相似文献