全文获取类型
收费全文 | 1597篇 |
免费 | 60篇 |
国内免费 | 4篇 |
专业分类
林业 | 148篇 |
农学 | 43篇 |
基础科学 | 3篇 |
275篇 | |
综合类 | 66篇 |
农作物 | 80篇 |
水产渔业 | 176篇 |
畜牧兽医 | 735篇 |
园艺 | 18篇 |
植物保护 | 117篇 |
出版年
2022年 | 22篇 |
2021年 | 42篇 |
2020年 | 14篇 |
2019年 | 22篇 |
2018年 | 25篇 |
2017年 | 36篇 |
2016年 | 54篇 |
2015年 | 67篇 |
2014年 | 84篇 |
2013年 | 123篇 |
2012年 | 94篇 |
2011年 | 122篇 |
2010年 | 51篇 |
2009年 | 57篇 |
2008年 | 105篇 |
2007年 | 110篇 |
2006年 | 110篇 |
2005年 | 105篇 |
2004年 | 111篇 |
2003年 | 93篇 |
2002年 | 71篇 |
2001年 | 48篇 |
2000年 | 30篇 |
1999年 | 13篇 |
1998年 | 9篇 |
1997年 | 7篇 |
1996年 | 2篇 |
1995年 | 5篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1989年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 2篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1977年 | 1篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1966年 | 1篇 |
1964年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有1661条查询结果,搜索用时 187 毫秒
991.
Toshiyuki Takano Tomomi Murakami Hiroshi Kamitakahara Fumiaki Nakatsubo 《Journal of Wood Science》2008,54(4):332-336
Formaldehyde adsorption and release tests of karamatsu (Larix leptolepis) bark and bark ingredients were performed. Karamatsu bark had good formaldehyde adsorption ability that was better than microcrystalline
cellulose. An acetone-soluble fraction from karamatsu bark, which might contain bark tannin, had excellent formaldehyde adsorption
ability, and was found to release a trace amount of the adsorbed formaldehyde, suggesting that its formaldehyde adsorption
was predominantly due to chemical adsorption. It was confi rmed that the acetone-soluble fraction played an important part
in formaldehyde adsorption by karamatsu bark. An acetone-insoluble fraction from karamatsu bark had good formaldehyde adsorption
ability as well as the bark, in spite of the residue after the removal of the acetone-soluble fraction. 相似文献
992.
993.
Mechanism of formaldehyde adsorption of (+)-catechin 总被引:1,自引:1,他引:0
Toshiyuki Takano Tomomi Murakami Hiroshi Kamitakahara Fumiaki Nakatsubo 《Journal of Wood Science》2008,54(4):329-331
The reaction of (+)-catechin with formaldehyde vapor was investigated as a model reaction of formaldehyde adsorption of (+)-catechin.
It was found by H nuclear magnetic resonance spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass
spectrometry, and gel permeation chromatography of the product that the vapor reaction of (+)-catechin with formaldehyde without
a solvent or a catalyst proceeds via methylolation, condensation, and polymerization. This is the same as the reaction in
a solvent in the presence of an acid or a base. The formation of polyoxymethylenes such as paraformaldehyde was not confirmed. 相似文献
994.
995.
M Wang H Kikuzaki C C Lin A Kahyaoglu M T Huang N Nakatani C T Ho 《Journal of agricultural and food chemistry》1999,47(5):1911-1914
Four acetophenone glycosides were isolated from the butanol-soluble fraction of thyme extracts. Their structures were determined by spectral methods (MS, NMR, and 2D-NMR). Among them, two new compounds, 4-hydroxyacetophenone 4-O-[5-O-(3, 5-dimethoxy-4-hydroxybenzoyl)-beta-D-apiofuranosyl]-(1-->2)-beta-D -gl ucopyranoside (1) and 4-hydroxyacetophenone 4-O-[5-O-(4-hydroxybenzoyl)-beta-D-apiofuranosyl]-(1-->2)-beta-D-+ ++gluc opyranoside (2), were determined. Compound 1 showed weak cytotoxicity, inhibiting DNA synthesis of human leukemia cells. 相似文献
996.
Optimal carbamate treatment conditions were studied for flower induction in seedlings of an asparagus cultivar ‘Mary Washington
500 W’. Flower induction was most accelerated by soaking seeds in 50 mg l−1 carbamate solution for 12 days at 25 °C under the fluorescent light. Longer exposure to carbamate over a 12 day period induced a higher percentage of seedlings
to flower. A higher percentage of flowering seedlings were male. Flower induction frequency among seven cultivars through
carbamate treatment widely ranged from 13 to 67%. ‘Geynlim’, ‘Mary Washington 500 W’ and ‘Welcome’ exhibited a high percentage
of flowering seedlings, while ‘Larac’ and ‘Vulkan’ showed low values. Only male flowers were induced in all-male cultivars.
Variation in pollen germination was found within all cultivars. ‘Geynlim’, ‘Cito’ and ‘Mary Washington 500 W’ showed high
values of average pollen germination. Application of carbamate compound to induce flower production can rapidly produce homogenic
cultivars which include both sexes. This is necessary for genetic studies and breeding purposes.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
997.
Masahiro Iwaoka Kazuhiro Aruga Rin Sakurai Koo Hyun Cho Hideo Sakai Hiroshi Kobayashi 《Journal of Forest Research》1999,4(3):195-200
Medium to large size harvester heads mounted on large machines are popular in Japan. These machines encounter some problems
during thinning operations,e.g. damage to residual stand and the compaction of soil. The performance of these large harvesters was compared with that of
smaller ones operating simultaneously in the same line thinning operation of the same stand. The results of a time study showed
that mean cycle times for the smaller and larger harvesters were not significantly different. This means that the work efficiency
of the smaller harvester can be at the same level as the larger harvester on sites similar to those of this study. The mean
values “Feed” element of the cycle time, however, were significantly different. Although this time difference appears to provide
an advantage to the larger harvester, simulation results show that the advantage is not great enough to significantly shorten
the total cycle times. That is to say, the work efficiency remains essentially the same even if the feeding performance of
the small size harvester becomes as high as that of larger ones. The small harvester performs adequately in thinning operations,
and is not inferior to the larger ones. This result indicates that there is economic potential for small base machines that
can be mounted with small harvester heads, resulting in less damage to residual trees and site soils during thinning operation.
A part of this paper was orally presented at the 109th Annual Meeting of the Japanese Forestry Society (1998).
The time study research presented in this paper was supported by the National Federation of Logging Contractors Cooperative
Associations. 相似文献
998.
999.
Rommaneeya LEELA-ARPORN Hiroshi OHTA Genya SHIMBO Noboru SASAKI Mitsuyoshi TAKIGUCHI 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2021,83(9):1459
The size of canine focal liver lesions (FLLs) is known to be one of the predicting criteria for malignancy. However, there are discrepancies for the measurement of maximum lesion size, resulting in contradicting results among studies and incidences of false positive outcomes. Thus far, the morphometric changes of FLLs for distinguishing malignancy from benignancy remains undocumented. This study aimed to investigate morphometric characteristics of FLLs using computed tomography (CT). CT images of 40 dogs with histopathological confirmation of 49 liver lesions, including 39 hepatocellular carcinomas and 10 nodular hyperplasias were retrospectively reviewed. The morphometric parameters including size (long and short axis diameters measured on transverse image), shape (measured by long to short axis (L/S) ratio), volume, and surface appearance of a liver lesion were evaluated using univariate and stepwise multivariate analyses, respectively. The results of univariate analysis showed that long and short axis diameters, L/S ratio, volume, and surface appearance of a lesion were significantly different between hepatocellular carcinomas and nodular hyperplasias. Multivariate analysis revealed that short axis diameter (>3.30 cm; odds ratio (OR): 36.1, 95% confidence interval (CI): 3.36–387.05, P=0.0031) and L/S ratio (>1.23; OR: 18.1, 95% CI: 1.61–205.12, P=0.0191) were independent predictors of malignancy, with the area under the curve of 0.9154. These results suggest that the combination of short axis diameter and L/S ratio is a promising tool for predicting liver malignancy with outstanding discriminating ability. 相似文献
1000.
M Abduh Ibnu Hajar Hiroshi Inada Masahide Hasobe Takafumi Arimoto 《Fisheries Science》2008,74(3):461-468
ABSTRACT: To understand the mechanism of the behavioral response in the capture process of how fish recognize fishing gear and then how they can avoid the gear, the visual acuity of Pacific saury Cololabis saira was investigated by histological examination of the retina of individuals in the size range of 75–365 mm fork length (FL). The contour map of cone density distribution shows that the highest cone density is located in the temporal area of the retina, which indicated the visual axis as the forward direction. The visual acuity (VA) depends both on the focal length of the lens and the number of cones in the retina. The lens diameter increased linearly from 1.40 to 4.73 mm with fish growth, while the cone density decreased gradually from 765 to 378 cells/0.01 mm2 . Our results show that the visual acuity increases proportionately from 0.057 to 0.140 for individuals ranging in FL from 75 to 365 mm as expressed by the equation VA = 0.0065 × FL 0.5271 ( r 2 = 0.9624). 相似文献