全文获取类型
收费全文 | 373篇 |
免费 | 19篇 |
专业分类
林业 | 10篇 |
农学 | 10篇 |
基础科学 | 2篇 |
26篇 | |
综合类 | 23篇 |
农作物 | 14篇 |
水产渔业 | 38篇 |
畜牧兽医 | 243篇 |
园艺 | 4篇 |
植物保护 | 22篇 |
出版年
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 2篇 |
2019年 | 7篇 |
2018年 | 7篇 |
2017年 | 7篇 |
2016年 | 3篇 |
2015年 | 13篇 |
2014年 | 9篇 |
2013年 | 10篇 |
2012年 | 18篇 |
2011年 | 21篇 |
2010年 | 9篇 |
2009年 | 4篇 |
2008年 | 12篇 |
2007年 | 17篇 |
2006年 | 18篇 |
2005年 | 18篇 |
2004年 | 18篇 |
2003年 | 11篇 |
2002年 | 14篇 |
2001年 | 14篇 |
2000年 | 16篇 |
1999年 | 21篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 9篇 |
1991年 | 12篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 11篇 |
1987年 | 13篇 |
1986年 | 8篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1970年 | 2篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1926年 | 1篇 |
排序方式: 共有392条查询结果,搜索用时 221 毫秒
21.
Mozammel M. Hoque Kazuyuki Inubushi Shu Miura Kazuhiko Kobayashi Han-Yong Kim Masumi Okada Shingo Yabashi 《Biology and Fertility of Soils》2001,34(6):453-459
An experiment was conducted in an Andosol paddy field in Shizukuishi (Iwate Prefecture, Japan) to determine the effects of free-air CO2 enrichment (FACE) on biological N2-fixation activity and soil microbial biomass C at three levels of N application. Rice (Oryza sativa L. cv. Akitakomachi) plants were grown under ambient CO2 or FACE (ambient +200 µmol mol-1 CO2) conditions throughout the growing season with each treatment having four replicated plots. Three levels of N fertilizer (high, standard and low; 15, 9 and 4 g N m-2, respectively) were applied to examine the effect of different N availability under both CO2 conditions. Soil samples were collected at four different times from upper and lower soil layers (0-1-cm and 1-10-cm soil depths, respectively) and analysed for biological N2-fixation (BNF) activity and microbial biomass C (MBC) by the acetylene reduction and chloroform fumigation-extraction methods, respectively. The amounts of chlorophyll-type compounds (Chls), an index of algal growth, and soil available C were also determined. Compared to the ambient CO2 treatment, the FACE treatment had significantly higher BNF activity in both the upper and lower soil layers at ripening only in low-N soil and at harvest at all three levels of N fertilization rates. MBC was significantly increased by FACE in both the upper and lower soil layers from the middle to later period of the growing season compared to the ambient CO2 treatment. The FACE treatment increased the Chls in the upper soil layers at ripening only in low-N soil and at harvest at all three levels of N fertilization rates. The amount of soil available C was not significantly different between FACE and ambient CO2 treatments in both the upper and lower soil layers throughout the cropping season. From these results it can be concluded that the FACE treatment had a significantly positive influence on BNF activity, MBC and Chls at different levels of N fertilization rates in paddy field during the cropping season. 相似文献
22.
23.
Hernández PA Notsu K Salazar JM Mori T Natale G Okada H Virgili G Shimoike Y Sato M Pérez NM 《Science (New York, N.Y.)》2001,292(5514):83-86
Magmatic carbon dioxide (CO2) degassing has been documented before the 31 March 2000 eruption of Usu volcano, Hokkaido, Japan. Six months before the eruption, an increase in CO2 flux was detected on the summit caldera, from 120 (September 1998) to 340 metric tons per day (September 1999), followed by a sudden decrease to 39 metric tons per day in June 2000, 3 months after the eruption. The change in CO2 flux and seismic observations suggests that before the eruption, advective processes controlled gas migration toward the surface. The decrease in flux after the eruption at the summit caldera could be due to a rapid release of CO2 during the eruption from ascending dacitic dikes spreading away from the magma chamber beneath the caldera. 相似文献
24.
Noguchi T Nakamura T Kimura M Zolensky ME Tanaka M Hashimoto T Konno M Nakato A Ogami T Fujimura A Abe M Yada T Mukai T Ueno M Okada T Shirai K Ishibashi Y Okazaki R 《Science (New York, N.Y.)》2011,333(6046):1121-1125
The reflectance spectra of the most abundant meteorites, ordinary chondrites, are different from those of the abundant S-type (mnemonic for siliceous) asteroids. This discrepancy has been thought to be due to space weathering, which is an alteration of the surfaces of airless bodies exposed to the space environment. Here we report evidence of space weathering on particles returned from the S-type asteroid 25143 Itokawa by the Hayabusa spacecraft. Surface modification was found in 5 out of 10 particles, which varies depending on mineral species. Sulfur-bearing Fe-rich nanoparticles exist in a thin (5 to 15 nanometers) surface layer on olivine, low-Ca pyroxene, and plagioclase, which is suggestive of vapor deposition. Sulfur-free Fe-rich nanoparticles exist deeper inside (<60 nanometers) ferromagnesian silicates. Their texture suggests formation by metamictization and in situ reduction of Fe(2+). 相似文献
25.
Y Ukishima M Kino H Kubota S Wada S Okada 《Journal of the Association of Official Analytical Chemists》1991,74(6):943-950
Thin-layer isoelectric focusing was applied to the identification of whale (Cetacea) species by using water-soluble sarcoplasmic proteins of skeletal muscles. Twenty-eight samples consisting of 4 species (10 samples) of baleen whales (Mysticeti) and 8 species (18 samples) of toothed whales (Odontoceti) were analyzed. Each sample (approximately 1 g) was electrophoresed with Ampholine PAGplate, pH 3.5-9.5. The electrophoretic profiles were species-specific on the 4 toothed whale species that did not have a marked intra-species difference, and all 4 baleen whale species. However, the profiles were not specific on the 4 other dolphin species, even though they were discriminable from the other 4 toothed whale species. Numerical values of pIs and relative peak heights were obtained by densitometric analysis of the isoelectro-focused protein bands. The bands were also species-specific for the 8 toothed whale species mentioned. The values may be applicable to species identification without the need for a standard sample, which may not be readily obtainable. Experiments on test samples of minke and sel whales showed that bloodletting with ice water made the densities of isoelectro-focused bands thinner, although species identification was still possible by using the inside part of muscles. Heat treatment at below 60 degrees C for 10 min caused little denaturation; at higher temperatures the protein bands were diminished in a temperature-dependent fashion. Therefore, the present isoelectric focusing analysis should be applicable to small samples of whale meat, excluding several species of dolphins. 相似文献
26.
T. Onaga H. Okada S. Hagiwara C. Nagashima H. Inoue W. Korczynski S. Kato 《Research in veterinary science》2001,71(3):189-195
The present study was planned to evaluate a role of nitric oxide (NO) in the regulation of regular ruminal contractions in conscious sheep. Intravenous infusion of S-nitroso-acetyl-DL-penicillamine (SNAP) at doses of 3-30 nmol kg(-1) min(-1)for 30 minutes inhibited both the amplitude and frequency of ruminal contractions in a dose-dependent manner. However, intravenous infusion of Nomega-nitro-L-arginine-methyl ester (L-NAME) at doses of 0.3-3.0 micromol kg(-1) min(-1)did not alter the basal tone of intraruminal pressure and the amplitude of ruminal contractions. The frequency of contractions was slightly inhibited by L-NAME infusion at 1.0 micromol kg(-1)min(-1). The effects of L-NAME were abolished by simultaneous infusion of L -arginine at 30 micromol kg(-1) min(-1). These results suggest that exogenous NO can diminish the ruminal contractions, while endogenous NO is not involved in the regulatory mechanism of basal tone and regular phasic contractions of the rumen in healthy sheep. 相似文献
27.
A Matsuda Tsuchida S Katayama N Okada T Okabe N Sasaki 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1992,54(3):447-452
The antigens gII, gIII and gVI were purified from the lysates of the pseudorabies virus (PRV) -infected HmLu-1 cells using Sepharose 4 B coupled with MAbs against these antigens. Mice immunized with either gII, gIII, gVI antigen or a mixture of them were challenged intraperitoneally with 8.5 x 10(3) plaque forming units of PRV. All the mice immunized with 1.5 and 4.5 micrograms of the mixture and 4.5 micrograms of the gIII antigen survived. The sera of mice immunized with the mixture had virus neutralizing activity which was independent of complement, hemagglutination inhibition activity, and recognized major (93 kilodaltons) and minor (129, 74, 68 and 50 kilodaltons) PRV proteins under reducing conditions in western blotting. The serological activity levels in the lower survival group were not different from those in the complete survival. These results indicate that the mixture of each glycoprotein is more effective for eliciting of protective immunities in mice and that serological activity do not always correlate with protection. 相似文献
28.
29.
30.