全文获取类型
收费全文 | 470篇 |
免费 | 13篇 |
国内免费 | 1篇 |
专业分类
林业 | 103篇 |
农学 | 20篇 |
66篇 | |
综合类 | 23篇 |
农作物 | 9篇 |
水产渔业 | 54篇 |
畜牧兽医 | 177篇 |
园艺 | 5篇 |
植物保护 | 27篇 |
出版年
2023年 | 1篇 |
2022年 | 3篇 |
2021年 | 11篇 |
2020年 | 9篇 |
2019年 | 7篇 |
2018年 | 10篇 |
2017年 | 8篇 |
2016年 | 16篇 |
2015年 | 13篇 |
2014年 | 19篇 |
2013年 | 40篇 |
2012年 | 30篇 |
2011年 | 28篇 |
2010年 | 17篇 |
2009年 | 20篇 |
2008年 | 30篇 |
2007年 | 35篇 |
2006年 | 27篇 |
2005年 | 30篇 |
2004年 | 29篇 |
2003年 | 20篇 |
2002年 | 19篇 |
2001年 | 16篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 5篇 |
1996年 | 9篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1987年 | 2篇 |
1984年 | 1篇 |
1979年 | 1篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1971年 | 1篇 |
排序方式: 共有484条查询结果,搜索用时 15 毫秒
101.
Nikaidou S Ishizuka M Maeda Y Hara Y Kazusaka A Fujita S 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2005,67(1):137-138
Green tea, one of the most popular beverages consumed in Asian countries, has been reported to possess anticarcinogenic and antimutagenic properties. The aim in this study is to test the radical scavenging effect of catechins and caffeine, which were major components of green tea, and if they really prevent oxygen radical-induced mutagenesis. We used TA102 strain of Salmonella typhimurium which is sensitive to hydroxyl radical in the Ames mutation assay. We found that caffeine did not show any effects on mutagenesis in this system, but catechin significantly reduced mutagenesis or genotoxicity caused by hydroxyl radical. This radical-scavenging action of catechins may indeed contribute to the anticarcinogenic activity of green tea as has been proposed. 相似文献
102.
The effect of compression and incision on wood veneer and plywood physical and mechanical properties
Maija Kymäläinen Akio Yamamoto Kasperi Sokka Lauri Rautkari 《Wood material science & engineering》2020,15(2):97-103
ABSTRACTDrying takes the largest share of energy in plywood production, and varying moisture content of veneers necessitates re-drying that often leads to over-dry veneers with deactivated surfaces, which may promote imperfect bonding. In order to decrease the drying time, reduce the need for re-drying of veneers, and improve the quality of plywood, birch and spruce veneers were subjected to pre-treatment by cold compression, incision, or a combination of the two. The effects of pre-treatment on the veneer and plywood quality were assessed by standard tests. Compression had a beneficial effect on water removal of the wettest veneers (spruce sapwood (SW) and birch), but some thickness reduction was observed in the veneers as well as the finished birch plywood. Compression led to thickness reduction of spruce veneers, but had no effect on SW plywood thickness likely due to higher viscoelasticity. Both compression and the combination of incising and compression levelled the moisture variation within the compressed stacks. Incision improved the modulus of elasticity of birch plywood, shear strength of SW plywood, and both bending and shear strengths of heartwood plywood. Higher surface pressure decreased the drying time of spruce SW in both plain compression and combined incision and compression pre-treatment. 相似文献
103.
The causes of soil alkalinization in the Songnen Plain of Northeast China were mainly analyzed from two aspects, natural and
anthropogenic. Natural factors of alkalinization are parent materials, topographic positions, freeze-thaw action, wind conveyance,
water properties and semi-arid/sub-humid climate. Some of them were always being neglected, such as freeze-thaw action and
wind conveyance. Anthropogenic causes are mainly population pressure, overgrazing and improper agricultural and economic policies.
In recent decades, overgrazing played a main role in secondary soil alkalinization, which led to the decline of Leymus chinensis grasslands. Now, the alkalinization is very severe, and more than 3.2 × 106 ha area has been affected by salt, which becomes one of the three largest sodic–saline areas in the world. 相似文献
104.
Verticillium dahliae isolates from potato on the island of Hokkaido (potato isolates) and those belonging to pathotypes A (eggplant pathotype),
B (tomato pathotype) and C (sweet pepper pathotype) were divided into three distinct groups by RAPD and REP-PCR. The three
DNA groups I, II, III consisted of pathotypes A and C, pathotype B and potato isolates, respectively. The potato isolates
were assigned to pathotype A on the basis of pathogenicity. Another set of potato isolates was further collected from eight
potato cropping regions on Hokkaido to further examine the relationships among them in detail. Only one of these isolates
was identified as DNA group II, but all the others were classified as DNA group III. Isolates from daikon, eggplant, and melon
on Hokkaido also belonged to DNA group III. These results suggest that V. dahliae isolates from Hokkaido are unique at the DNA level and different from other pathotype A isolates in Japan.
Received 28 February 2000/ Accepted in revised form 6 November 2000 相似文献
105.
Effect of sodium acetate on the adhesion to porcine gastric mucin in a Lactococcus lactis strain grown on fructose
下载免费PDF全文
![点击此处可从《Animal Science Journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hiromi Kimoto‐Nira Naoko Moriya Seishi Yamasaki Akio Takenaka Chise Suzuki 《Animal Science Journal》2016,87(6):802-808
The association of lactic acid bacteria with mucosal surfaces plays important roles in the beneficial effects of these bacteria on human health, such as colonization of the gastrointestinal tract for pathogen antagonism. Previously, we found that the adhesion of Lactococcus lactis 7‐1 to porcine gastric mucin was higher with fructose than with lactose, galactose or xylose as the carbon source. In this study, we examined the effect of growth conditions on the adhesion of strain 7‐1 grown on fructose. Medium components affect the adhesion: the adhesion of strain 7‐1 grown with sodium acetate was higher than that without it. The enhancement of adhesion by sodium acetate was not observed under aerobic conditions. Cellular properties grown with or without sodium acetate were characterized: strain 7‐1 grown with sodium acetate had similar sugar contents, and different fatty acid composition to those grown without it. Strain 7‐1 grown with sodium acetate showed significantly lower cell yield and significantly higher hydrophobicity than those grown without it, which is associated with higher adhesion. Fructose and sodium acetate are frequently used in the food industry; this study may reveal a simple way to enhance the adhesion of lactic acid bacteria by growing them with these substances. 相似文献
106.
107.
Ishii N Nakahigashi K Baba T Robert M Soga T Kanai A Hirasawa T Naba M Hirai K Hoque A Ho PY Kakazu Y Sugawara K Igarashi S Harada S Masuda T Sugiyama N Togashi T Hasegawa M Takai Y Yugi K Arakawa K Iwata N Toya Y Nakayama Y Nishioka T Shimizu K Mori H Tomita M 《Science (New York, N.Y.)》2007,316(5824):593-597
Analysis of cellular components at multiple levels of biological information can provide valuable functional insights. We performed multiple high-throughput measurements to study the response of Escherichia coli cells to genetic and environmental perturbations. Analysis of metabolic enzyme gene disruptants revealed unexpectedly small changes in messenger RNA and proteins for most disruptants. Overall, metabolite levels were also stable, reflecting the rerouting of fluxes in the metabolic network. In contrast, E. coli actively regulated enzyme levels to maintain a stable metabolic state in response to changes in growth rate. E. coli thus seems to use complementary strategies that result in a metabolic network robust against perturbations. 相似文献
108.
A fraction containing low-molecular-weight peptides that catalyzes redox reactions between electron donors and O2 to produce ·OH, was partially purified from wood-decaying cultures of the brown-rot fungusTyromyces palustris. Polyclonal antibodies raised to the fraction were used for immunogold labeling of transverse sections of sapwood of spruce in various stages of degradation byT. palustris to demonstrate the cellular localization of the ·OH-producing substance. Initially, the wood cell wall was attacked primarily by fungal hyphae growing in the cell lumen. During the early stages of degradation, the gold label was localized in the fungal cytoplasm and cell wall and in the extracellular slime sheath surrounding the fungal cell wall. The gold label also was found throughout the wood cell wall, although the cell wall remained almost intact so long as the fungal hyphae remained in the lumen. Thus, the ·OH-producing substance is secreted by the hyphae into the lumen, and it diffuses through the S3 layer into the S2 layer and the middle lamella. The role of this ·OH-producing system in wood degradation byT. palustris is discussed. 相似文献
109.
Shin-ichiro Tohmura Atsuko Ishikawa Kohta Miyamoto Akio Inoue 《Journal of Wood Science》2012,58(1):57-63
A mechanism of acetaldehyde emission from wood induced by the addition of ethanol was proposed. It is known that acetaldehyde
generation is due to the oxidation of ethanol via a metabolic process involving alcohol dehydrogenase (ADH) in living bodies.
However, it remains unclear whether the enzymatic alcohol oxidation is applicable to wood. We investigated possible factors
of wood parts, conditioning, storage sites, and heating and sterilization treatments on acetaldehyde emission using the syringe
method and HPLC analysis. We reconfirmed that acetaldehyde emission was observed only when ethanol was added to wood. Greater
acetaldehyde emissions were obtained in heartwood compared to sapwood in both Japanese cedar (Cryptomeria japonica D. Don) and Japanese cypress (Chamaecyparis obtusa Endl.) specimens. In addition, an acetaldehyde conversion rate of 1–2 mol% was determined in green cedar heartwood samples,
while, conversely, air-dried cedar heartwood samples showed 4–5 mol%. Ethylene oxide gas sterilization had the effect of decreasing
acetaldehyde emission on air-dried wood, but not on green wood. Autoclave sterilization could completely prevent acetaldehyde
emissions from both green and air-dried wood. These results suggested that an original ADH in wood and an attached ADH from
the outside via microorganisms onto wood were assumed to be the primary causes of acetaldehyde emissions from wood induced
by the addition of ethanol. 相似文献
110.
Genetic similarity of iridoviruses from Japan and Thailand 总被引:3,自引:0,他引:3
Iridovirus infection causes serious economic damage in marine cultured fish in Japan, Hong Kong and Singapore, and the incidence of this disease has been increasing. Iridovirus of sea bass from offshore Hong Kong was isolated to determine the genetic similarities of the causative agents. The genomic DNA of iridovirus was purified and cloned. Four DNA clones were randomly chosen and sequenced to generate primers for the polymerase chain reaction (PCR). Corresponding DNA fragments of iridoviruses from sea bass from offshore Hong Kong, red sea bream in Japan and grouper in Thailand were detected. The analogous PCR products from geographically diverse iridoviruses may indicate a widespread distribution of an iridovirus of a single origin. 相似文献