全文获取类型
收费全文 | 307篇 |
免费 | 4篇 |
国内免费 | 2篇 |
专业分类
林业 | 34篇 |
农学 | 3篇 |
基础科学 | 2篇 |
48篇 | |
综合类 | 5篇 |
农作物 | 6篇 |
水产渔业 | 64篇 |
畜牧兽医 | 132篇 |
园艺 | 6篇 |
植物保护 | 13篇 |
出版年
2022年 | 5篇 |
2021年 | 13篇 |
2020年 | 3篇 |
2019年 | 5篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 3篇 |
2015年 | 10篇 |
2014年 | 20篇 |
2013年 | 16篇 |
2012年 | 17篇 |
2011年 | 21篇 |
2010年 | 14篇 |
2009年 | 20篇 |
2008年 | 12篇 |
2007年 | 26篇 |
2006年 | 20篇 |
2005年 | 20篇 |
2004年 | 15篇 |
2003年 | 20篇 |
2002年 | 13篇 |
2001年 | 2篇 |
2000年 | 7篇 |
1999年 | 2篇 |
1998年 | 3篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 2篇 |
1988年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1955年 | 1篇 |
1952年 | 1篇 |
1949年 | 1篇 |
排序方式: 共有313条查询结果,搜索用时 31 毫秒
91.
Daisuke Hattori Tanaka Kenzo Nozomi Yamauchi Kazuo Okamura Irino Joseph Jawa Kendawang Ikuo Ninomiya 《Soil Science and Plant Nutrition》2013,59(2):218-228
Enrichment planting with climax trees such as dipterocarps is required to rehabilitate degraded tropical forests in Southeast Asia, because these forests have been damaged by various anthropogenic activities. Severely degraded tropical secondary forests are the most important targets for enrichment planting in the region, because secondary forest trees potentially provide moderate conditions for planted seedlings by preventing strong sunlight and high temperatures. In an enrichment planting site located in Sarawak, Malaysia, we explored how variation in secondary forest structure (biomass and stand density) and soil (nutrient and water) conditions influenced the mortality and growth rates of planted dipterocarp seedlings (Parashorea macrophylla, Wyatt-Sm. ex P.S. Ashton) over the period from 2000–2007. Experimental plots were set up on different topographical features (slopes and valleys). Using the data collected, we demonstrated the ways in which environmental factors, such as soil nitrogen content, relate to climax tree seedling growth and mortality in degraded tropical secondary forests dominated by the genera Macaranga, Ficus, and Glochidion. Stand density and total aboveground biomass of secondary forest trees were significantly lower in the valley plots than on the slopes, whereas soil total nitrogen and water contents were significantly higher in valley plots. Over seven years, the total biomass of trees increased, whereas the density of secondary forest trees decreased in all plots. Nutrient stocks (nitrogen, phosphorus, potassium, calcium, and magnesium) in the soil (0–5?cm) also decreased over seven years in all plots. Height, diameter, and mortality of planted seedlings were higher in the valley plots than on slopes. Multiple stepwise regression demonstrated significant positive effects of total soil nitrogen and water content on the relative growth rate of seedlings over seven years. There were no significant relationships between seedling mortality and any of the environmental factors measured, including soil conditions. We conclude that (1) seedling growth was enhanced by soil total nitrogen rather than by available phosphorus or potassium, and (2) planted seedlings grew faster and died more often in the valley plots than on the slopes. 相似文献
92.
Determination of optimal conditions for parthenogenetic activation and subsequent development of rat oocytes in vitro 总被引:5,自引:0,他引:5
Mizutani E Jiang JY Mizuno S Tomioka I Shinozawa T Kobayashi J Sasada H Sato E 《The Journal of reproduction and development》2004,50(1):139-146
The present study was undertaken to determine optimal conditions for parthenogenetic activation and subsequent development of rat oocytes. Oocytes from immature Wistar-Imamichi (WI) and Sprague Dawley (SD) rats were activated by electrical stimulation in combination with 6-dimethylaminopurine (6-DMAP) to assess whether different rat strains display different responses to activation treatment. Since the cleavage rates of activated oocytes were significantly higher in WI than SD strain rats, WI rats were used for the subsequent experiments to determine the effects of post-hCG time, culture duration, different activation protocols (electrical stimulation with 6-DMAP or ionomycin with 6-DMAP) and osmolarity of the activation medium on the activation and subsequent development of WI rat oocytes. For oocytes activated by electrical stimulation combined with 6-DMAP, the percentages of oocytes that were activated and that developed to blastocysts were higher when oocytes were collected at 18-20 h than at any other time points after hCG injection (16, 22-24 h). Culturing for 2-6 h before activation treatment markedly decreased the percentage of activated oocytes that developed to beyond the four-cell stage. There were no differences in the percentages of oocytes with pronuclear formation and subsequent development to the two-cell and blastocyst stages between oocytes that were activated by electrical stimulation or ionomycin, both followed by 6-DMAP treatment. Activation of oocytes by ionomycin and 6-DMAP, both in low osmolarity media (246 mOsM), markedly increased the cleavage rates and percentages of high quality blastocysts (71%). The optimal conditions determined in the present study with simplified activation protocols and high efficiency of activation and subsequent development of WI rat oocytes will be helpful for further research involving nuclear transfer in the rat. 相似文献
93.
94.
Yezo spruce trees (Picea jezoensis), approximately 40-year-old were inoculated with eight ophiostomatoid fungi associated withIps typographus f.japonicus to compare relative virulence of the fungi. Among them,Ophistoma penicillatum formed the longest necrotic lesion on inner bark around inoculation points, followed byO. aenigmaticum, Ceratocystis polonica, andO. bicolor, whileC. polonica formed a larger dry zone in sapwood than the other fungi. Yezo spruce trees were also mass inoculated withC. polonica, O. penicillatum, O. piceae singly or mixed to demonstrate the ability of the fungi to kill Yezo spruce trees. The trees inoculated withC. polonica, O. penicillatum or the mixed inoculum showed discoloration of needles in the early summer of the next year and died by autumn. However, the
trees inoculated withO. piceae or the control inocula did not die, except for one tree. These results indicated thatC. polonica andO. penicillatum were more virulent thanO. piceae and suggested that they might be at least partially responsible for the mortality of the beetle-infested Yezo spruce trees.
Part of this study was supported by the Sumitomo Foundation, Japan to Y. Yamaoka and I. Takahashi.
Part of this study was presented at the 107th meeting of the Japanese Forestry Society, April 1–4, 1996, Tsukuba, Ibaraki,
at the 42nd annual meeting of the Mycological Society of Japan, May 16–17, 1998, Kyoto, and at the 110th meeting of the Japanese
Forestry Society, April 2–5, 1999, Matsuyama, Ehime.
Contribution No. 143, Laboratories of Plant Pathology and Mycology, Institute of Agriculture and Forestry, University of Tsukuba. 相似文献
95.
Keisuke KAWASE Jumpei TOMIYASU Kazuyuki BAN Ryosuke ONO Satoshi ANDO Aya ONO Ran KIMURA Kanako TOMISAWA Motozumi MATSUI Shun-ichi SHIIHARA 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2021,83(9):1454
Lions (Panthera leo) breed well under captivity, so contraception has been commonly conducted for population management, leading to a demand for a less invasive and reversible contraceptive approach in lions. In this study, we examined the efficacy of a commercial gonadotropin-releasing hormone vaccine as a method of suppressing reproductive activity in a sexually matured female lion. Under behavioral restraint, the vaccine was injected twice (days 0 and 109). After the initial vaccination, ovarian activity is still observed. After the second vaccination, contraceptive effect was confirmed for 246 days until restart of estrous cycles. We confirmed only a slight swelling around the injection site after the second vaccination. This study may suggest an alternative option for a contraceptive method in lions. 相似文献
96.
97.
Ayumi Kobayashi Sayaka Takahashi Masaaki Ono Kiyoshi Tanaka Masato Kishima Masato Akiba Ikuo Uchida 《Acta veterinaria Scandinavica》2014,56(1):31
Background
Salmonella enterica serovar Enteritidis is a zoonotic pathogen. Human infections are associated with contaminated eggs and egg products. In Japan, since 1989, the incidence of food-borne disease caused by S. Enteritidis has increased and a pandemic has occurred; however, little is known about changes that occurred before and after this pandemic event in the dominant lineage of isolates from food-producing animals. This study aimed to determine the S. Enteritidis lineages in Japan over the last few decades by using multilocus variable-number tandem repeat analysis (MLVA).Findings
MLVA was used to analyse 79 S. Enteritidis isolates collected from chickens (n = 63), cattle (n = 12), pigs (n = 2), and goats (n = 2) during 1975–2009. The S. Enteritidis isolates showed 14 different MLVA allele combinations, which were classified into two major clusters (A and C) and a minor cluster (B). All the 62 isolates in cluster A were isolated after 1988, whereas 13 of the 17 isolates belonging to cluster B and C were isolated before 1989.Conclusions
The MLVA results showed that cluster C was predominant before 1989, and isolates in cluster A disseminated since 1989 and replaced the previous dominant clone, suggesting that isolates of cluster A originated from imported S. Enteritidis infection. 相似文献98.
Shun TAKEO Daichi SATO Koji KIMURA Yasunori MONJI Takehito KUWAYAMA Ryoka KAWAHARA-MIKI Hisataka IWATA 《The Journal of reproduction and development》2014,60(2):92-99
The aim of the present study was to address the effect of resveratrol-mediated
upregulation of sirtuin 1 (SIRT1) during oocyte maturation on mitochondrial function, the
developmental ability of oocytes and on mechanisms responsible for blockage of polyspermic
fertilization. Oocytes collected from slaughterhouse-derived ovaries were cultured in
TCM-199 medium supplemented with 10% FCS and 0 or 20 µM resveratrol (Res). We examined the
effect of Res on SIRT1 expression in in vitro-matured oocytes (Exp 1);
fertilization and developmental ability (Exp 2); mitochondrial DNA copy number (Mt
number), ATP content and mitochondrial membrane potential in matured oocytes (Exp 3); and
the time required for proteinase to dissolve the zona pellucida following in
vitro fertilization (as a marker of zona pellucida hardening), as well as on
the distribution of cortical granules before and after fertilization (Exp 4). In Exp 1,
the 20 µM Res treatment upregulated protein expression of SIRT1 in oocytes. In Exp 2, Res
treatment improved the ratio of normal fertilization and the total cell number of
blastocysts. In Exp 3, Res treatment significantly increased the ATP content in matured
oocytes. Additionally, Res increased the overall Mt number and mitochondrial membrane
potential, but the effect was donor-dependent. In Exp 4, Res-induced zona hardening
improved the distribution and exocytosis of cortical granules after in
vitro fertilization. In conclusion, Res improved the quality of oocytes by
improving mitochondrial quantity and quality. In addition, Res added to the maturation
medium enhanced SIRT1 protein expression in oocytes and improved fertilization via
reinforcement of the mechanisms responsible for blockage of polyspermic fertilization. 相似文献
99.
100.