全文获取类型
收费全文 | 49篇 |
免费 | 12篇 |
国内免费 | 18篇 |
专业分类
海洋学 | 67篇 |
综合类 | 12篇 |
出版年
2024年 | 1篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 2篇 |
2013年 | 2篇 |
2012年 | 2篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 5篇 |
2008年 | 5篇 |
2007年 | 2篇 |
2006年 | 8篇 |
2005年 | 3篇 |
2004年 | 1篇 |
2003年 | 2篇 |
2001年 | 5篇 |
2000年 | 1篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 6篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有79条查询结果,搜索用时 15 毫秒
21.
评“HAIRTAIL FISHES FROM CHINESE COASTAL WATERS (TRICHIURIDAE… 总被引:1,自引:1,他引:1
李春生先生在“Marine sciences”1992年第4卷第3期第212-219页上发表题为“GairtailfishesfromChineseCoastalWaters(Trichiuridae)”(《中国近海带鱼类》)一文,把中国近海带鱼分成3个种并定名两个新种。本文作者对该文进行比较和分析,认为该文从基本概念到原始数据的测量,和资料的分析整理等方面,存在第列的错误,某些形态描述与事实不符 相似文献
22.
青岛文昌鱼(Branchiostoma japonicus)采自于青岛沙子口海区,在室内进行周年培育。每月采集样品,经测量、固定以及组织切片观察,研究了其周年卵巢和精巢的发育规律。结果表明,室内培育的文昌鱼一周年内全长没有明显变化,仅体质量在繁殖期即其性腺发育至Ⅴ期时有明显增大(P0.05=,精卵排空后则恢复原来体质量。文昌鱼1 a内在夏季6~7月繁殖1次,能自行排放卵和精子,排空后个体的卵巢或精巢,在适宜的条件下,经历Ⅰ、Ⅱ、Ⅲ、Ⅳ和Ⅴ期的发育过程,进行下一轮的性腺发育。文昌鱼精巢在Ⅳ期前先于卵巢发育,两者在Ⅳ期前发育都不同步,精巢处于Ⅳ期时间较长,一般从3月持续到5月,而卵巢处于Ⅳ期一般是在4月~5月。 相似文献
23.
Neuropeptide Y(NPY) is a 36-amino acid peptide of the neuropeptide Y family that plays key roles in the regulation of food intake. In this study,we focused on NPY m RNA expression changes around feeding time and during food deprivation in olive flounder. The olive flounder NPY m RNA levels were analyzed in different tissues and a high level of expression was detected in the brain. We also demonstrated a correlation between NPY expression levels in the brain and feeding schedule. NPY expression levels in olive flounder maintained on a daily scheduled feeding regimen increased shortly before feeding and decreased after the scheduled feeding time. Compared with the-1 h group before feeding,NPY expression in the 3 h group after feeding decreased significantly( P <0.05). Food deprivation led to an 81.7% decrease in NPY m RNA levels in the 24 h fasted group(P <0.05) and a 91.7% decrease in the 48 h fasted group(P <0.05). Therefore,our study demonstrates that NPY expression is associated with food intake in olive flounder. This result reveals the function of NPY in regulating food intake and its potential importance in olive flounder aquaculture. 相似文献
24.
25.
INTRODUCTIONTriploidyinductionandgynogeneticdiploidinductionasmainpartsofchromosomalmanipula tionhavebeenplayingmoreandmoreimportantrolesinmodernfishbreeding .Mosttriploidfisharesterileandtheirreducedgonadaldevelopmentresultsinimprovementofgrowthratea… 相似文献
26.
Steroid sex hormones,such as estradiol-17β(E2)and testosterone(T),are important regulators of sex change in fish.In this study,we examined the effects of E2 treatment on the dynamics of E2 and T during gonadal differentiation in the olive flounder Paralichthys olivaceus using histology and radioimmunoassay(RIA).Flounder larvae were divided into five groups(G0–G4),and fed with 0 (control),0.2,2,20 and 100 mg E2/kg feed from 35 to 110 day post hatching(dph).Fish growth in the G1 and G2 groups was not significantly different from that of the control group(P0.05),while fish in the G3 and G4 groups were less active and showed growth depression and high mortality.The gonads of fish in the G3 and G4 groups were smaller and surrounded by hyperplastic connective tissue.The frequency of females in the G0–G4 groups was 54.5%,75.0%,100%,100%and 93.3%,respectively.The RIA analyses of E2 and T showed that T levels decreased during gonadal differentiation,and increased slightly at the onset of ovarian differentiation,while E2 levels increased gradually and peaked at the onset of ovarian differentiation in the control group.In the E2-treated groups,T levels decreased before the onset of ovarian differentiation.E2 levels were high on the 48 dph,but declined to a lower level on the 54 dph, and then increased gradually during gonadal differentiation.And a sharp increase of E2 levels were observed in all E2-treated groups at the onset of ovarian differentiation.The data suggest that T and E2 play important roles during gonadal differentiation,and an E2 dose of 2 mg/kg feed could induce sex reversal in P.olivaceus. 相似文献
27.
Steroid sex hormones, such as estradiol-17β (E2) and testosterone (T), are important regulators of sex change in fish. In
this study, we examined the effects of E2 treatment on the dynamics of E2 and T during gonadal differentiation in the olive
flounder Paralichthys olivaceus using histology and radioimmunoassay (RIA). Flounder larvae were divided into five groups (G0-G4), and fed with 0 (control),
0.2, 2, 20 and 100 mg E2/kg feed from 35 to 110 day post hatching (dph). Fish growth in the G1 and G2 groups was not significantly
different from that of the control group (P>0.05), while fish in the G3 and G4 groups were less active and showed growth depression and high mortality. The gonads of
fish in the G3 and G4 groups were smaller and surrounded by hyperplastic connective tissue. The frequency of females in the
G0-G4 groups was 54.5%, 75.0%, 100%, 100% and 93.3%, respectively. The RIA analyses of E2 and T showed that T levels decreased
during gonadal differentiation, and increased slightly at the onset of ovarian differentiation, while E2 levels increased
gradually and peaked at the onset of ovarian differentiation in the control group. In the E2-treated groups, T levels decreased
before the onset of ovarian differentiation. E2 levels were high on the 48 dph, but declined to a lower level on the 54 dph,
and then increased gradually during gonadal differentiation. And a sharp increase of E2 levels were observed in all E2-treated
groups at the onset of ovarian differentiation. The data suggest that T and E2 play important roles during gonadal differentiation,
and an E2 dose of 2 mg/kg feed could induce sex reversal in P. olivaceus. 相似文献
28.
29.
多倍体诱导会造成物种中不同基因的表达水平变化不同,以内参基因作为对照的相对实时定量PCR是检测基因表达水平变化的一种高效方法,这就需要对多倍体中的内参基因进行筛选以获得较适宜的参比基因。本研究以二倍体和三倍体牙鲆肌肉和脑组织为对象,以绝对定量及2–ΔCt等方法分析管家基因18S rRNA、β-肌动蛋白基因(β-actin),β-2-微球蛋白基因(b2m),3-磷酸甘油醛脱氢酶基因(gapdh),核糖体蛋白L17基因(rpl17),α-微管蛋白基因(α-tub),延伸因子-1-α基因(ef1-α)和泛素结合酶基因(ubc-e)的表达水平稳定性。绝对定量分析发现18S rRNA和α-tub的表达在牙鲆二、三倍体肌肉之间有显著性差异,其他基因的表达没有显著性差异,利用2–ΔCt分析方法分析发现只有α-tub的表达在二、三倍体牙鲆肌肉之间有显著性差异,其他基因的表达没有显著性差异;在牙鲆三倍体的脑和二倍体的脑之间,这些基因的表达均没有显著性差异。综合基因表达稳定性和Normfinder分析的结果发现,ef1-α是定量分析牙鲆三倍体的肌肉和二倍体的肌肉之间基因表达差异的较适合的内参基因,α-tub、ubc-e、rpl17、β-actin只在其中一种分析方法中符合要求,而其他基因不符合任何一种分析方法的要求;ef1-α、rpl17是定量分析牙鲆二、三倍体脑组织之间基因表达差异的比较适合的内参基因,β-actin只在基因表达稳定性上符合要求,其他基因不符合任何一种分析方法的要求。本研究为分析牙鲆二倍体和三倍体同一组织之间基因表达的差异奠定了基础。 相似文献
30.
本文通过qPCR方法,研究了我国重要海水鱼类——牙鲆(Paralichthys olivaceus)雌、雄成体组织以及性腺分化期的脑、性腺中gnrh1、gnrh2和gnrh3的表达水平。结果显示,gnrh1分布于所有检测的组织:在脑、垂体、肾脏和肝脏中高表达,在性腺中表达相对较低;gnrh2则在雌、雄性的肝脏以及雄性的肠、肾脏、眼睛和头肾中;而gnrh3只在雄性的肾脏、眼睛和肌肉中检测到微弱表达。人工诱导的牙鲆雌核发育鱼苗分别用17β-雌二醇(E2)和17α-甲基睾酮(MT)处理,使其分化为雌性或雄性个体表型。在性腺分化期的脑中,gnrh1的表达呈现上升趋势,在全长(total length,TL)4 cm鱼苗中,E2组的表达显著高于MT组(P<0.05);gnrh2在2 cm TL时E2组显著高于MT组(P<0.05),随后在E2和对照组的表达水平均出现下降趋势;gnrh3在2 cm TL时E2和对照组的表达均显著高于MT组(P<0.05),自6 cm TL时MT和E2组的表达开始下降。在性腺中,三种gnrh在性腺分化前2 cm TL表达量都相对较高,随后呈现下降趋势。综上,推测牙鲆gnrh1可能参与了性腺分化的启动、分化过程及性腺发育,gnrh2主要参与了性腺分化的启动,gnrh3主要参与了性腺分化的启动和分化过程。 相似文献