首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   210篇
  免费   2篇
  国内免费   1篇
林业   27篇
农学   3篇
基础科学   5篇
  37篇
综合类   4篇
农作物   8篇
水产渔业   37篇
畜牧兽医   76篇
园艺   2篇
植物保护   14篇
  2023年   1篇
  2022年   1篇
  2020年   2篇
  2019年   2篇
  2018年   1篇
  2017年   2篇
  2016年   4篇
  2015年   1篇
  2014年   7篇
  2013年   23篇
  2012年   12篇
  2011年   11篇
  2010年   5篇
  2009年   9篇
  2008年   19篇
  2007年   16篇
  2006年   16篇
  2005年   15篇
  2004年   15篇
  2003年   12篇
  2002年   6篇
  2001年   8篇
  2000年   6篇
  1999年   3篇
  1998年   2篇
  1997年   1篇
  1996年   1篇
  1992年   1篇
  1991年   2篇
  1989年   1篇
  1988年   1篇
  1986年   1篇
  1983年   1篇
  1982年   1篇
  1979年   1篇
  1978年   1篇
  1972年   1篇
  1967年   1篇
排序方式: 共有213条查询结果,搜索用时 656 毫秒
71.
The chemical conversion of red pine sulfuric acid lignin (Klason lignin) (SAL) as an acid hydrolysis lignin sample to water-soluble arylsulfonates of lignin derivation (i.e., phenolized SAL) was investigated. Treatment of phenolized SAL with chlorosulfonic acid followed by alkali hydrolysis gave water-soluble sulfonated products with a sulfonic acid group on their aromatic nuclei quantitatively. The products possess 2.0 SO3Na/C9 C6. In contrast, the content of sulfuric acid group in sulfonated SAL was only 0.33C9. Chlorosulfonation of 1-guaiacyl-l-p-hydroxyphenylethane as a phenolized guaiacyl lignin model compound revealed that the sulfonyl chloride group was introduced at thepara position of an aromatic methoxyl group, theortho position of a phenolic hydroxyl group, or both.  相似文献   
72.
We discovered that some isolated eel skeletal muscle cells exhibited green fluorescence under a fluorescence stereomicroscope, and we successfully isolated a novel fluorescent protein from the eel muscle homogenate. The protein was a monomer with a molecular mass of 16.5–17 kDa and showed minor and major peaks at 280 and 493 nm, respectively, in the absorption spectrum. The molar extinction coefficient at 493 nm was 41,300 M−1 cm−1 and A280/A493 was 0.083. Excitation and emission spectra of the protein showed maxima at 493 and 527 nm, respectively. Heat treatment at 95°C for 10 min or 5% trichloroacetic acid treatment of the protein caused aggregation of the protein but did not release any fluorescent components such as FAD into the supernatant after centrifugation. Fluorescence of the protein remained after native PAGE, but not after SDS-PAGE. These results indicate that the purified fluorescent protein is not a flavoprotein, and that its fluorescent chromophore is a covalently bound one, such as green fluorescent protein (GFP) from jellyfish Aequoria victoria, but that its fluorescence requires its native conformation within the protein. Based on these results, we can conclude that the fluorescent protein obtained from eel skeletal muscle is a novel GFP-like protein.  相似文献   
73.
This study investigated consumer behavior towards meat across Asia and Pacific-Rim countries. Mail surveys were undertaken in 1994 and 1995. Data was obtained from 6197 households in Japan, the USA (mainland and Japanese–Americans in Hawaii), Australia, Thailand, Korea, Taiwan and China. The data were mainly analyzed using cluster analysis to determine the distance between each country and to classify countries into groups. Japanese respondents purchased beef more frequently than respondents from other countries. The average amount purchased on each occasion was far more for Australian respondents than for respondents from other countries, while Japanese purchased far less. Respondents in Japan, Korea, China and Australia thought beef was the most expensive meat, whereas lamb was thought to be the most expensive in the remaining countries. Chinese respondents indicated the highest consciousness of price indexes. The level of uneasiness about eating meat indicated by Asian respondents was relatively strong compared with respondents in Hawaii, the USA and Australia. Average ratings (semantic differential scale) on plans for future meat consumption were higher for beef than for other meats in Korea and China, whereas chicken was rated higher in the other countries. From the dendrogram, surveyed countries were classified into three groups: Japan, Taiwan and Korea; Thailand and China; and the USA, Japanese–Americans and Australia. Among them, the first and second clusters merged into a larger cluster, the 'Asian' group.  相似文献   
74.
The therapeutic efficacy of atovaquone against Babesia gibsoni was examined in three dogs experimentally infected with B. gibsoni isolated from naturally infected dogs in Aomori Prefecture, Japan. Once parasitemia reached 10%, atovaquone was administered orally (30 mg/kg twice daily for 7 days). Within 2 days of atovaquone treatment, the parasite disappeared from blood smears without any clinical side effects. Anemia and thrombocytopenia were significantly improved in all the dogs. However, a polymerase chain reaction assay revealed that a B. gibsoni marker gene was intermittently present in peripheral blood after atovaquone therapy, indicating that the organism had not been eliminated, and parasites reappeared in blood smears 33 days after the last treatment. To investigate the change in sensitivity against atovaquone, an in vitro sensitivity test was performed using peripheral blood obtained from an untreated dog that was infected with the original parasite isolate, and from two of the experimentally infected and atovaquone-treated animals (blood was collected at the time of the post-treatment recurrence of the B. gibsoni infection). Atovaquone was added to the culture medium to final concentrations of 0.1, 1, 10, 100, and 1000 nM. For the untreated parasites, complete growth inhibition occurred at 1000 nM of atovaquone, whereas the recurrent parasites were inhibited by only 39.52 +/- 8.34% and 31.31 +/- 8.14% at this concentration after 48 h of incubation. Thus, the recurring parasites were less sensitive to atovaquone than the untreated originally isolated parasites.  相似文献   
75.
Herpesvirus papio 2 (HVP2), which infects baboons, is much more closely related genetically and antigenically to monkey B virus (BV) than to human herpes simplex virus 1(HSV1) and other related herpes viruses. The usefulness of HVP2 as an alternative test antigen in immunoblotting assays to detect BV-antibody in macaque monkey sera was assessed. Six HVP2 proteins reacted with BV-positive sera in immunoblotting. No specific bands could be detected with BV-negative sera. These results show the usefulness of HVP2 antigen as an alternative and safer antigen than authentic BV antigen in detecting BV antibody in immunoblotting.  相似文献   
76.
中华绒螯蟹线粒体DNA 12S rRNA基因片段的序列研究   总被引:4,自引:0,他引:4  
首次进行了中华绒螯蟹(Eriocheir sinensis)线粒体DNA12SrRNA的序列分析。参考果蝇、蚤状序列对中华绒螯蟹线粒体DNA12SrRNA基因片段做了引物设计、PCR扩增及序列测定,结果得到457bp的碱基序列,其A、T、G、C含量分别为159bp(34.79%)、177bp(38.73%)、51bp(11.16%)、70bp(15.32%)、与果蝇、蚤状的相同基因片段的序列含量基  相似文献   
77.
ABSTRACT A collection 160 isolates of Cercospora kikuchii was made from South America and 245 from Japan. DNA fingerprint patterns were analyzed based on amplified fragment length polymorphism among the sample isolates, dividing the isolates into seven lineages (I to VII). Partial nucleotide sequence analyses of the beta-tubulin gene supported this division into seven lineages. Lineages I and III commonly existed in South America and Japan. In all, 136 of the 160 isolates from South America and 223 of the 245 isolates from Japan belonged to lineage I, indicating that lineage I was the major lineage in each area; 5 isolates from South America and 8 isolates from Japan belonged to lineage III. Lineages II (12 isolates) and IV (2 isolates) were specific to Japan and lineages V (3 isolates), VI (1 isolate), and VII (15 isolates) specifically existed in South America. These results suggest that the population genetic structure of C. kikuchii was different between South America and Japan, but the dominance of lineage I was common between the two areas.  相似文献   
78.
79.
It is essential to analyze chemical properties including the amount of various materials and the soil colloid characteristics in forest soils to forecast wood production and the distribution of and variations in the environmental functions of forest soils, such as conservation of stream water and carbon sequestration. Approximately 70% of the forest soils in Japan consists of Brown Forest Soils (BFS), which are considered to be typical zonal soils under the humid-temperate and warm-temperate regime of Japan. BFS were subclassifled into several groups according to the soil moisture environment along the slope and morphological properties. However, even the same type of soil may display different properties depending on the climatic conditions, parent materials and vegetation types. In the present study, the variations in the carbon content, nitrogen content, cation exchange capacity and some properties depending on the parent materials, were clarified by using 34 sola of BFS, and 3 sola of black soils (BLS) for comparison, which were distributed in the submontane zone of the Kanto and Chubu districts in central Japan under the same climatic conditions. We observed differences in the pH, cation exchange capacity, base saturation and clay content among BFS samples derived from various parent materials. The BFS derived from volcanic ash contained obviously larger amounts of carbon and nitrogen than the BFS derived from other parent materials. However, the BFS derived from volcanic ash differed from the BLS derived from volcanic ash in the vertical distribution pattern of carbon and nitrogen. Thus, even in the submontane zone of the Kanto and Chubu districts, the chemical properties of BFS varied considerably with the parent materials. It was concluded that the classification of BFS by the parent materials was useful for evaluating the ability of the BFS, that cover 70% of the forests in Japan, to store various materials.  相似文献   
80.
A unique lipoprotein profile was found in the plasma of cultured Japanese eel,Anguilla japonica which accumulated more lipid in its muscle than in its liver. The plasma lipoprotein level of Japanese eels was in excess of 54 mg ml1, a concentration considered to be hyperlipoproteinemic in relation to other teleosts. The plasma lipoproteins consisted of very low density lipoprotein (VLDL, density (d)<1.006 g ml1) low density lipoprotein (LDL, 1.0061), high density lipoprotein 2 (HDL2, 1.0851), and HDL3 (1.1001). VLDL, but not HDL, was the main component in the plasma of Japanese eels, unlike most teleosts where HDL is the main component. An additional lipoprotein, vitellogenin (1.2101), was induced by the injection of estradiol-17ß (E2), but VLDL was the main plasma component even in the E2-treated eels. VLDL was a triacylglycerol (TG)-rich lipoprotein and possessed two apolipoprotein (apo) B-like proteins of molecular weights (Mr) 260K and 230K as main components.LDL, HDL2, and HDL3 were revealed to consist of heterogeneous components by a density gradient ultracentrifugation. LDL was separated into three subclasses of LDL1 (1.0301), LDL2 (1.0431), and LDL3 (1.0671). LDL1 with apo B-like protein of Mr 230K was a TG-rich lipoprotein, while both LDL2 and LDL3 were cholesterol ester-rich lipoproteins with apo A-I-and A-II-like proteins of Mr 25K and 14K. The particle sizes of HDL2 and HDL3 subclasses differed, although all of HDL2 and HDL3 subclasses possessed apo A-I-and A-II-like proteins of Mr 25K and 14K as main components. To our knowledge, this is the first report of detailed plasma lipoprotein profile in Japanese eels.Corresponding author: till August 18, 1996 and after April 19, 1997: at the above address. From August 19, 1996 till April 18. 1997: c/o Dr. N.H. Haunerland, Department of Biological Sciences. Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号