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排序方式: 共有164条查询结果,搜索用时 15 毫秒
91.
Tetsuya Umino Teruyuki Kajihara Hiroshi Shiozaki Toshiyuki Ohkawa Dal-Sang Jeong Kenichi Ohara 《Fisheries Science》2009,75(4):909-919
Twelve populations of Girella punctata, from widespread locations of the species’ range in Japan and Korea, were screened for sequence variability within the mitochondrial
DNA (mtDNA) control region (n = 128) and at five polymorphic microsatellite loci (n = 547) to determine the genetic structure maintaining population integrity. mtDNA variability of 132 variable sites within
a 334-bp region reveals shallow genetic differentiation across populations. The weak differentiation of G. punctata was partly supported by the screening of five polymorphic microsatellite loci. However, hierarchical analysis of molecular
variance and principal component analysis on the basis of allele frequencies in microsatellite loci extracted a subtle substructure
in a subsidiary population and in near-subsidiary populations in the semi-enclosed Seto Inland Sea. 相似文献
92.
We evaluated the response of Japanese larch (Larix kaempferi Sieb. & Zucc.) to elevated atmospheric CO(2) concentration ([CO(2)]) (689 +/- 75 ppm in 2002 and 697 +/- 90 ppm in 2003) over 2 years in a field experiment with open-top chambers. Root activity was assessed as nitrogen, phosphorus and potassium uptake rates estimated from successive measurements of absorbed amounts. Dry matter production of whole plants was unaffected by elevated [CO(2)] in the first year of treatment, but increased significantly in response to elevated [CO(2)] in the second year. In contrast, elevated [CO(2)] increased the root to shoot ratio and fine root dry mass in the first year, but not in the second year. Elevated [CO(2)] had no effect on tissue N, P and K concentrations. Uptake rates of N, P and K correlated with whole-plant relative growth rates, but were unaffected by growth [CO(2)], as was ectomycorrhizal colonization, a factor assumed to be important for nutrient uptake in trees. We conclude that improved growth of Larix kaempferi in response to elevated [CO(2)] is accompanied by increased root biomass, but not by increased root activity. 相似文献
93.
94.
Nobuhito Sekiya Motonori Tomitaka Nobuaki Oizumi Adam Gabriel Pyuza Richard James Shayo Anne Niediwe Assenga Takayoshi Iemoto Kenji Ishido Yasunori Saiki Kenji Tamura Takahiro Nakamura 《Paddy and Water Environment》2017,15(4):847-859
The productivity of irrigated rice is low in Tanzania. We hypothesized that this is caused by the absence of a packaged application of basic cultivation techniques. A baseline survey of 31 rice irrigation schemes across the country revealed that a large proportion of fields were cultivated without a technical package. Thus, a package was introduced to each of the 31 schemes through a farmer-to-farmer (FTF) extension approach. First, selected key farmers (KFs) were trained with the basic cultivation techniques at agricultural training institutes. Second, the KFs transferred their knowledge to intermediate farmers (IFs) by working together at a demo-field established in each scheme. Third, the KFs and IFs exhibited the rice performance to other farmers (OFs). The paddy yield across the 31 schemes greatly increased from the pre-training level of 2.4 t ha?1 to 3.6 t ha?1after the FTF extension. However, the farmer interviews in the four selected schemes suggested that the technical package was not adopted by all farmers owing to the time-consuming nature of the FTF extension. It was inferred from our study that the low productivity of irrigated rice is caused by the absence of basic cultivation techniques in Tanzania. However, the post-training yield remained relatively low compared with high-yields (4.3–8.4 t ha?1) recorded in cultivar selection trials and high-performing schemes in the county. This “yield gap” could be partly ascribed to the insufficient technical diffusion and the technique-dependent adoption among OFs. 相似文献
95.
Shiro Itoi Koki Ikeguchi Masaki Kaneniwa Ryuji Kuwahara Ichiro Ohara Noriko Ishida Michiaki Yamashita Shugo Watabe 《Fisheries Science》2007,73(2):429-439
ABSTRACT: Fast skeletal muscles of Japanese flounder Paralichthys olivaceus and red sea bream Pagrus major were examined for quantitative and qualitative changes of mitochondrial ATP synthase (Fo F1 -ATPase) in association with rearing temperatures. The specific activities of Fo F1 -ATPase from Japanese flounder reared at 10°C, 15°C and 25°C for 4 weeks were determined to be 81 ± 11, 74 ± 13 and 83 ± 11 nmol/min·mg mitochondrial protein, respectively. The corresponding activity from red sea bream reared at 8°C for 5 weeks was determined to be 65 ± 9 nmol/min·mg mitochondrial protein, which was higher than 33 ± 9 nmol/min·mg mitochondrial protein in fish reared at 23°C. The contents of α- and β-F1 -ATPase in total mitochondrial proteins were not significantly different between fish reared at different temperatures for the two fish species. However, the contents of β-F1 -ATPase in the total fast skeletal muscle extracts, prepared from Japanese flounder reared at 10°C, were 2.1- and 2.9-fold higher than those for fish reared at 15°C and 25°C, respectively. The corresponding content from red seabream reared at 8°C was 2.2-fold higher than that for fish reared at 23°C. Therefore, the changes in Fo F1 -ATPase depending on rearing temperatures were species-specific. 相似文献
96.
Yuya Kumagai Hideki Kishimura Weeranuch Lang Takayoshi Tagami Masayuki Okuyama Atsuo Kimura 《Marine drugs》2022,20(4)
The glycoside hydrolase family 17 β-1,3-glucanase of Vibrio vulnificus (VvGH17) has two unknown regions in the N- and C-termini. Here, we characterized these domains by preparing mutant enzymes. VvGH17 demonstrated hydrolytic activity of β-(1→3)-glucan, mainly producing laminaribiose, but not of β-(1→3)/β-(1→4)-glucan. The C-terminal-truncated mutants (ΔC466 and ΔC441) showed decreased activity, approximately one-third of that of the WT, and ΔC415 lost almost all activity. An analysis using affinity gel containing laminarin or barley β-glucan revealed a shift in the mobility of the ΔC466, ΔC441, and ΔC415 mutants compared to the WT. Tryptophan residues showed a strong affinity for carbohydrates. Three of four point-mutations of the tryptophan in the C-terminus (W472A, W499A, and W542A) showed a reduction in binding ability to laminarin and barley β-glucan. The C-terminus was predicted to have a β-sandwich structure, and three tryptophan residues (Trp472, Trp499, and Trp542) constituted a putative substrate-binding cave. Linker and substrate-binding functions were assigned to the C-terminus. The N-terminal-truncated mutants also showed decreased activity. The WT formed a trimer, while the N-terminal truncations formed monomers, indicating that the N-terminus contributed to the multimeric form of VvGH17. The results of this study are useful for understanding the structure and the function of GH17 β-1,3-glucanases. 相似文献
97.
Yasuo Nakamura Tadashi Nakano Tatsuya Yurimoto Yukio Maeno Takayoshi Koizumi Akio Tamaki 《Fisheries Science》2010,76(6):931-941
We assessed the reproductive cycle of the venerid clam Meretrix lusoria by histological analysis of the gonads. Individuals for study were collected from natural populations on the Shirakawa tidal
flat, Ariake Sound, and from populations that had been transplanted from the Shirakawa flat to the Oi flat in Tokyo Bay. In
both study areas, the reproductive cycle was synchronized between sexes. Gonads of the clam started to develop in early spring
and matured during the summer. Mass spawning occurred in the late summer/early fall. The clam matured at a shell length of
17–20 mm, which is much smaller than previously considered. While trophic conditions and salinity differed considerably in
the two study areas, water temperatures showed similar seasonal changes (12°C during the winter and around 30°C during the
summer). Thus, temperature probably controlled gonadal development. The coincidence of the period of spawning with the period
of frequent intrusion of hypoxic waters into the tidal flats in Tokyo Bay suggests that such hypoxic events interfere with
clam recruitment and are at least partly responsible for the disappearance of the natural population at this location. 相似文献
98.
Yasutomo Hoshika Makoto Watanabe Naoki Inada Takayoshi Koike 《Water, air, and soil pollution》2012,223(8):5017-5025
We examined the effects of ozone and elevated CO2 concentration in summer on the growth and photosynthetic traits of three representative birch species in Japan (mountain birch, Monarch birch, and white birch). Seedlings of the three birch species were grown in 16 open-top chambers and were exposed to two levels of ozone (6 and 60?nmol?mol?1 for 7?h per day) in combination with two levels of CO2 (370?C380 and 600???mol?mol?1 for daytime) from July to October. No adverse effects of ozone were found in the Monarch birch or the white birch, but elevated ozone in summer reduced branch biomass and net photosynthesis, and accelerated leaf abscission, in the mountain birch. Elevated CO2 promoted root development and thereby reduced the ratio of shoot dry mass (stem + branch) to root dry mass (S/R ratio) in the mountain birch and white birch. In contrast, there was no difference in dry mass between ambient and elevated CO2 for the Monarch birch, due to downregulation of photosynthesis. Studies of the combined effect of CO2 and ozone revealed that elevated CO2 did not ameliorate the effect of ozone on mountain birch in late summer. In considering the ameliorating effect of CO2 on ozone damage, it is necessary to take account of the species and the season. 相似文献
99.
Ryuichiro Kimura Takayoshi Rokkaku Shinji Takeda Masachika Senba Naoki Mori 《Marine drugs》2013,11(11):4267-4278
In this study, we analyzed the size-dependent bioactivities of fucoidan by comparing the cytotoxic effects of native fucoidan and fucoidan lipid nanoparticles on osteosarcoma in vitro and in vivo. In vitro experiments indicated that nanoparticle fucoidan induced apoptosis of an osteosarcoma cell line more efficiently than native fucoidan. The more potent effects of nanoparticle fucoidan, relative to native fucoidan, were confirmed in vivo using a xenograft osteosarcoma model. Caco-2 cell transport studies showed that permeation of nanoparticle fucoidan was higher than native fucoidan. The higher bioactivity and superior bioavailability of nanoparticle fucoidan could potentially be utilized to develop novel therapies for osteosarcoma. 相似文献
100.
Hideaki Korai Nan Ling Takayoshi Osada Osamu Yasuda Atsushi Sumida 《Journal of Wood Science》2011,57(5):401-407
An air-injection press was developed to prevent particleboard from blowing out during the manufacturing process. The air-injection
press, which has holes punched in the heating plates, injects high-pressure air into the board through the holes of one plate
and releases the air through the holes of the other plate. The high-pressure air forces out vapor trapped within the board,
thus preventing blowout. The newly developed press reduced the pressing time required for manufacturing board from high-moisture-content
particles. However, the manufactured boards exhibited mechanical properties and dimensional stability inferior to conventionally
manufactured boards. 相似文献