全文获取类型
收费全文 | 320篇 |
免费 | 12篇 |
国内免费 | 1篇 |
专业分类
林业 | 80篇 |
农学 | 14篇 |
41篇 | |
综合类 | 16篇 |
农作物 | 2篇 |
水产渔业 | 33篇 |
畜牧兽医 | 124篇 |
园艺 | 1篇 |
植物保护 | 22篇 |
出版年
2022年 | 2篇 |
2021年 | 7篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2018年 | 5篇 |
2017年 | 8篇 |
2016年 | 9篇 |
2015年 | 10篇 |
2014年 | 16篇 |
2013年 | 26篇 |
2012年 | 28篇 |
2011年 | 20篇 |
2010年 | 12篇 |
2009年 | 13篇 |
2008年 | 20篇 |
2007年 | 28篇 |
2006年 | 23篇 |
2005年 | 21篇 |
2004年 | 19篇 |
2003年 | 15篇 |
2002年 | 12篇 |
2001年 | 8篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 2篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1986年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有333条查询结果,搜索用时 69 毫秒
101.
102.
Masaki Suzuki Hiroshi Akitsu Kohta Miyamoto Shin-ichiro Tohmura Akio Inoue 《Journal of Wood Science》2014,60(3):207-214
Acetaldehyde emissions from particleboard, fiberboard, and plywood were studied using the small chamber method and high-performance liquid chromatography analysis. The chamber tests were conducted for 1 month to examine the time dependence of acetaldehyde emission. Effects of temperature and relative humidity were also examined. Acetaldehyde emissions from these wood-based materials decreased rapidly and their behavior could be described by an exponential function or by the sum of two exponential functions. This result suggests that in an adequately ventilated atmosphere, the acetaldehyde emission factor decreases quickly following the board’s production. Under fixed absolute humidity conditions, the initial acetaldehyde emission factor was larger under higher temperature conditions, but tended to show almost the same value after 14 days. This suggests that higher temperatures promote higher initial concentrations and a faster decline of acetaldehyde. A semi-empirical linear equation was obtained for the early stage relationship between the emission factor and temperature. Under fixed temperature conditions, higher relative humidity caused a larger acetaldehyde emission factor throughout the testing period, and it did not result in a significantly faster decline in emissions. The relationship between acetaldehyde emission and relative humidity can be described using an exponential function. 相似文献
103.
Motoki SASAKI Yoko AMANO Daisuke HAYAKAWA Toshio TSUBOTA Hajime ISHIKAWA Toshihiro MOGOE Seiji OHSUMI Masafumi TETSUKA Akio MIYAMOTO Yutaka FUKUI Teguh BUDIPITOJO Nobuo KITAMURA 《The Journal of reproduction and development》2014,60(1):62-67
In this study, we examined the existence and structure of areolae and the
steroidogenesis of areolar trophoblast cells in the Antarctic minke whale placenta
morphologically and immunohistochemically. Placentas were collected from the 15th, 16th
and 18th Japanese Whale Research Program under Special Permit in the Antarctic (JARPA) and
1st JARPA II organized by the Institute of Cetacean Research in Tokyo, Japan. The opening
and cavity of fetal areolae formed by taller columnar trophoblast cells (areolar
trophoblast cells) with long microvilli and a bright cytoplasm, as compared with the
trophoblast cells of the chorionic villi interdigitating with the endometrial crypts, were
recognized in observations of serial sections. The opening of the areolar cavity was
hidden by chorionic villi with areolar trophoblast cells. Furthermore, a closed pouch-like
structure lined by tall columnar cells similar to areolar trophoblast cells within the
stroma of chorionic villi was noticed and continued to the areolar cavity, with the
opening seen on serial sections. In a surface investigation of the chorion and endometrium
by SEM, maternal (endometrial) areolae irregularly surrounded by endometrial folds were
obvious. Moreover, we distinguished areolar trophoblast cells with long microvilli
attached with many blebs from trophoblast cells. In our immunohistochemical observations,
a steroidogenic enzyme, cytochrome P450 side chain cleavage enzyme (P450scc), was detected
with strong immunoreactivity in trophoblast cells. However, areolar trophoblast cells
showed weak or no immunoreactivity for P450scc. 相似文献
104.
Kaoru NISHINE Hiroshi AOKI Yoshihiro SAKODA Akio FUKUSHO 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2014,76(12):1635-1639
Field isolates of BVDV which do not show the exaltation of Newcastle disease virus (END)
phenomenon (END–) are rarely reported. In this study, 45 BVDV field isolates
from cattle in Hokkaido prefecture in Japan were analyzed by the reverse plaque formation
method, the END method and observation of cytopathic effects. END– virus was
detected in 34 of 45 isolates (75.6%), although 35 of 45 field isolates contained END
phenomenon positive virus as the predominant virus population. We propose that
END– viruses are widely distributed in the field and that it is possible that
the mixture of biologically distinct BVDV correlates with the appearance of disease in
infected animals. 相似文献
105.
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
106.
Nakamura T Noguchi T Tanaka M Zolensky ME Kimura M Tsuchiyama A Nakato A Ogami T Ishida H Uesugi M Yada T Shirai K Fujimura A Okazaki R Sandford SA Ishibashi Y Abe M Okada T Ueno M Mukai T Yoshikawa M Kawaguchi J 《Science (New York, N.Y.)》2011,333(6046):1113-1116
The Hayabusa spacecraft successfully recovered dust particles from the surface of near-Earth asteroid 25143 Itokawa. Synchrotron-radiation x-ray diffraction and transmission and scanning electron microscope analyses indicate that the mineralogy and mineral chemistry of the Itokawa dust particles are identical to those of thermally metamorphosed LL chondrites, consistent with spectroscopic observations made from Earth and by the Hayabusa spacecraft. Our results directly demonstrate that ordinary chondrites, the most abundant meteorites found on Earth, come from S-type asteroids. Mineral chemistry indicates that the majority of regolith surface particles suffered long-term thermal annealing and subsequent impact shock, suggesting that Itokawa is an asteroid made of reassembled pieces of the interior portions of a once larger asteroid. 相似文献
107.
弱光照射和无机营养供给对冷藏绿芦笋品质变化的影响 总被引:9,自引:0,他引:9
绿芦笋嫩茎基部切口插入含有N、P、K营养的琼脂凝胶中 ,在 (6± 0 2 )℃下贮藏。贮藏期间 ,分别以有效光量子束密度 (PPFD)为 2 μmol·m-2 ·s-1的红色发光二极管和白色荧光灯作为弱光源 ,每天 2 4h连续照射绿芦笋 2 1d。结果表明 ,红光和白光对冷藏绿芦笋品质的保持具有相似的效果。供给无机营养的处理在红光或白光照射下 ,色值 (a 和ΔE ab)变化率、粗纤维含量增长率和可溶性固形物减少率为最低 ,其次是无营养供给的红光或白光处理 ,以黑暗处理为最高 ;供给无机营养处理的芦笋嫩茎伸长率大于无营养处理的 ;光线照射与否和无机营养供给有无与芦笋失重率之间无明显相关性 相似文献
108.
Kazuyuki Inubushi Miwa Yashima Shunsuke Hanazawa Akio Goto Kisho Miyamoto Tatsushi Tsuboi 《Soil Science and Plant Nutrition》2020,66(1):247-253
ABSTRACT This study aims to characterize soil chemical properties and microbial biomass, greenhouse gas production, and organic matter dynamics in upland rice field as affected by the long-term fertilizer managements in Uganda. Soil total C (TC) and N (TN) contents were in the relatively smaller range under different fertilizer treatments, even after 20 crop seasons. However, available phosphate contents showed positive correlation with average yield of upland rice. Incubation experiments were conducted under aerobic or under flooding conditions to measure CO2, methane, and nitrous oxide productions. After the incubation, soil samples were extracted to quantify nitrification rate for aerobic condition and ammonification rate for flooding condition. Soil microbial biomass carbon (MBC) and nitrogen were measured. Stable isotope ratio of 13C and 15N were also determined for the soil samples. CO2 production potential under aerobic condition was higher than the flooding condition. The qCO2 (CO2/MBC) in the treatment applied with compost tended to be higher than the other treatments. Positive correlation between nitrous oxide production and nitrification was found. The delta 13C values of the soil samples indicated that the effect of C4 plants before rice cultivation still remained, while the contribution of biological N2 fixation was little according to delta 15N values. These results indicate that soil microbial biomass in upland rice field of the long-term fertilizer experiment in Uganda was characterized with higher qCO2. Greenhouse gas production was affected by fertilizer management, while soil organic C before the long-term experiment still remained in the experiment. 相似文献
109.
We derive a two-way volume equation for estimating the apparent culm volume of one of the largest bamboo species, Phyllostachys pubescens Mazel ex Houz. The volume equation was derived from the assumptions that (1) the relative culm form can be expressed by Kunze’s
equation and (2) normal form-factors at two different relative heights are steady at constants independent of culm sizes.
A total number of 200 sample culms were collected from a stand of P. pubescens in Mt. Toshima, Kumamoto Prefecture, western Japan, and were randomly bisected into two sets of data, i.e. modeling and test
data. For the modeling data, normal form-factors at 0.6 and 0.9 in relative height were steady at 0.908 and 0.448, respectively.
The coefficients of the volume equation were determined based on these steady values of the normal form-factors. For the test
data, the apparent culm volume was estimated from diameter at breast height and culm height with the determined volume equation.
The mean error and root mean square error of the estimated culm volume were, respectively, 8.120 × 10−5 and 3.291 × 10−3 m3, and there was no significant difference between estimated and actual volume. In conclusion, the two-way volume equation
presented here appears to be convenient for predicting the apparent culm volume for P. pubescens. 相似文献
110.
Shin Kato Kenichiro Fujii Setsuzo Yumoto Masao Ishimoto Tatsuhiko Shiraiwa Takashi Sayama Akio Kikuchi Takeshi Nishio 《Breeding Science》2015,65(2):154-160
The present study was conducted to evaluate the benefits of indeterminate growth habit in breeding to improve yield potential of Japanese soybean varieties, which exclusively have determinate growth habit. Two populations of recombinant inbred lines (RILs) derived from crosses between determinate Japanese cultivars and indeterminate US cultivars were grown in Akita and Kyoto, and seed weight per plant (SW) and its components were compared between indeterminate and determinate RILs. The difference of SW between the two growth habits in RILs varied depending on maturation time. The SW of early indeterminate lines was significantly higher than that of early determinate ones in Akita, but not in Kyoto. Among yield components, the number of seeds per pod was constantly larger in indeterminate lines than that in determinate ones irrespective of maturation time. The number of seeds per plant and the number of pods per plant of the indeterminate lines were greater than those of the determinate lines in early maturation in Akita. These results suggest that the indeterminate growth habit is an advantageous characteristic in breeding for high yield of early maturing soybean varieties in the Tohoku region. 相似文献