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   83篇
  免费   8篇
  国内免费   29篇
  2022年   1篇
  2021年   3篇
  2020年   3篇
  2019年   4篇
  2018年   1篇
  2017年   2篇
  2016年   4篇
  2015年   1篇
  2014年   3篇
  2013年   6篇
  2012年   13篇
  2011年   3篇
  2010年   5篇
  2009年   4篇
  2008年   3篇
  2007年   8篇
  2006年   7篇
  2005年   4篇
  2004年   1篇
  2003年   5篇
  2002年   3篇
  2001年   10篇
  2000年   1篇
  1999年   4篇
  1998年   5篇
  1997年   5篇
  1996年   3篇
  1995年   1篇
  1994年   1篇
  1993年   1篇
  1991年   1篇
  1985年   1篇
  1984年   1篇
  1982年   1篇
  1980年   1篇
排序方式: 共有120条查询结果,搜索用时 15 毫秒
111.
目的:探讨急性胰腺炎(AP)恢复期患者血清肝细胞生长因子(HGF)、表皮生长因子(EGF)、成纤维细胞生长因子-2(FGF-2)、再生蛋白-I(Reg-I)等再生相关细胞因子水平及其与胰腺功能的关系。方法:选取AP恢复期患者130例,其中轻症AP组56例、重症AP组74例。另选取健康体检合格者60例,设为对照组。检测所有受试对象的血清HGF、EGF、FGF-2、Reg-I及粪弹力蛋白酶-1(FE-1),以及空腹血糖(FBG)、胰岛素及C肽水平。对血清再生相关细胞因子与胰腺内外分泌功能进行相关性分析。结果:轻症AP组、重症AP组血清FBG、胰岛素、C肽以及HGF、EGF、FGF-2、Reg-I水平均高于对照组,粪FE-1低于对照组(P0.05或P0.01);重症AP组血清FBG、胰岛素、C肽以及HGF、EGF高于轻症AP组,粪FE-1低于轻症AP组(P0.05)。胰腺外分泌功能轻中度受损组、重度受损组血清HGF、EGF、FGF-2、Reg-I水平均高于正常范围组(P0.05或P0.01)。重度受损组患者的血清HGF、EGF均高于轻中度受损组(P0.05)。糖耐量异常组、糖尿病组血清HGF、EGF、FGF-2、Reg-I水平均高于正常血糖组。糖尿病组血清HGF、EGF均高于糖耐量异常组(P0.05)。AP恢复期患者血清HGF、EGF均与FE-l水平呈负相关,均与空腹胰岛素水平呈正相关(P0.01)。结论:急性胰腺炎恢复期患者血清HGF、EGF、FGF-2、Reg-I等再生相关细胞因子水平较高,血清HGF、EGF与FE-l水平呈负相关,与空腹胰岛素水平呈正相关,可能通过与相应的受体结合而激活细胞信号转导机制,促进胰腺细胞及间质成分的再生与积聚,最终发挥胰腺修复与再生的作用。  相似文献   
112.
为研究玻璃化冷冻后猪卵母细胞纺锤体、染色体和微丝的变化,从屠宰猪卵巢表面直径2—5mm卵泡中采集未成熟(GV)期卵母细胞,由GV期卵母细胞经成熟培养获得体外成熟(MⅡ)期卵母细胞。GV期和MⅡ期卵母细胞各分为3组对照组、冷冻保护剂处理组和玻璃化冷冻组。MⅡ期卵母细胞经分组处理后直接用于激光扫描共聚焦显微镜(LSCM)观察样本;而GV期卵母细胞处理后先经44h成熟培养,再用作LSCM观察样本。供试卵母细胞经固定、免疫荧光染色后,于LSCM下观察。结果表明,冷冻保护剂处理组GV期卵母细胞经成熟培养后,其纺锤体结构、染色体排列与微丝分布正常率分别为42.9%、89.6%和28.6%;玻璃化冷冻组此3项指标的正常率分别为10.1%、36.4%和16.9%,两组间差异显著(P<0.05);除冷冻保护剂处理组染色体正常率与对照组无较大差异外,两试验组的其他指标均明显低于对照组(分别为79.5%、93.1%和72.3%,P<0.05)。MⅡ期卵母细胞冷冻保护剂处理组的纺锤体结构、染色体排列与微丝分布正常率分别为34.4%、61.3%和47.9%,而冷冻组分别为12.9%、56.7%和37.2%,两组均显著低于对照组(分别为78.3%、90.1%和72.8%,P<0.05)。结果表明,猪GV期和MⅡ期卵母细胞经冷冻保护剂处理或玻璃化冷冻保存后,均造成了纺锤体、染色体和微丝不可逆的损伤,这可能是影响卵母细胞成熟、受精与发育的重要原因。  相似文献   
113.
不同转基因抗虫棉对棉铃虫抗虫性的时空动态   总被引:12,自引:4,他引:8  
利用2个对Bt抗性水平不同的棉铃虫品系,测定了转Bt和CpTI基因双价抗虫棉(SGK321)和Bt棉(GK12,33B)杀虫活性的时间和空间动态变化。结果表明,2类3种抗虫棉杀虫活性共同表现为:(1) 时间动态上均呈现前高后低的下降趋势;(2) 空间动态上表现为,在生长前期以叶的活性最高,中后期以铃和蕾的活性较高;(3) 对敏感品系的活性高于对抗性品系。不同点表现为:(1)双价棉在生长中后期(8~9月份)活性明显高于Bt棉;(2)双价棉对抗性品系的活性表现更稳定。  相似文献   
114.
WUJIARUI 《Cell research》1999,9(3):163-170
In eukaryote,nuclear structure is a key component for the functions of eukaryotic cells.More and more evidences show that the nuclear structure plays important role in regulating DNA replication.The nuclear structure provides a physical barrier for the replication licensing,participates in the decision where DNA replication initiates,and organizes replication proteins as replication factory for DNA replication.Through these works,new concepts on the regulation of DNA replication have emerged,which will be discussed in this minireview.  相似文献   
115.
The Mountains of Southwest China (MSC) – the most important mountain system in East Asia – creates physical barriers to migration and isolates organisms in different regions. In this study, we explored the genetic structure and phylogeography of Biston suppressaria, a moth species widely distributed in MSC and south China, based on three mtDNA and three ncDNA loci. MtDNA revealed high genetic differentiation among the geographical populations and divided B. suppressaria into five phylogroups (A–E). With the exception of phylogroups B and E which are sympatric, the other three phylogroups have their own distinct distribution areas. Four population differentiations occurred, and the divergence time was consistent with the three phases of the Qinghai–Tibet Movement and Kunhuang Movement, respectively. In contrast, ncDNA did not reveal any phylogeographical structure. Incomplete lineage sorting is considered the most plausible cause of the discordance between mtDNA and ncDNA genes, after excluding secondary admixture and Wolbachia infection. A complex combination of topography and geological movements of south China and MSC contributes to the complex evolutionary history of B. suppressaria.  相似文献   
116.
Mitogen-activated protein kinases (MAPKs) play important roles in signal transduction and regulation of various aspects of saprotrophic and pathogenic growth in plant pathogenic fungi. We have generated a Botrytis cinerea knock-out mutant in the bmp3 gene encoding a homologue of the yeast Slt2 cell wall integrity MAPK. The Δ bmp3 mutant showed reduced vegetative growth on various media, strongly impaired conidiation and loss of sclerotia formation. Growth retardation of the mutant was enhanced in media with low osmolarity, whereas nearly wild-type growth rates were observed under high osmolarity conditions. The Δ bmp3 mutant did not show increased susceptibility to cell wall damage induced by glucanase, Calcofluor White or Nikkomycin Z, but was more susceptible to the oxidizing agent paraquat and the phenylpyrrole fungicide fludioxonil. Δ bmp3 conidia showed normal germination and germ tube growth on agar, but excessive germ tube elongation on hard surfaces and reduced penetration efficiency, indicating a defect in surface sensing. After penetration, development of necrotic lesions induced by the Δ bmp3 mutant was retarded. All these defects were restored by genetic complementation of the mutant with the wild-type bmp3 gene.  相似文献   
117.
ABSTRACT

Several batrachoidids have been known to produce sounds associated with courtship and agonistic interactions, and their repertoires have been studied acoustically and behaviourally. In contrast, sound production of the Lusitanian toadfish Halobatrachus didactylus, although often noted, has not been acoustically studied.

This sedentary predator of Northeastern Atlantic coastal waters is usually found in sandy and muddy substrates, under rocks or crevices. Sound recordings were made in Ria Formosa, a lagoon complex in southern Portugal. The sound producing apparatus was studied in adult individuals of both sexes captured by local fishermen.

It is shown that this species produces acoustic emissions similar to other batrachoidids. It produces a long, rhythmical, tonal sound, often in choruses, which is comparable to the boatwhistle or hum signals of Opsanus and Porichthys, and a complex of signals that were classified as grunts, croaks, double croaks and mixed calls (‘grunt-croak’). As in other toadfishes, H. didactylus presents sonic muscles connected to a bi-lobed swimbladder. Asynchronous contractions of the sonic muscles were detected when massaging the ventral surface of the fish.  相似文献   
118.
Proteus species are common opportunistic bacteria and foodborne pathogens. The proper detection of Proteus can effectively reduce the occurrence of food-borne public health events. Proteus mirabilis and Proteus vulgaris are the two most important pathogens in the Proteus genus. In this study, a dual TaqMan Real-Time PCR method was established to simultaneously detect and distinguish P. mirabilis and P. vulgaris in samples. The method exhibited good specificity, stability, and sensitivity. Specifically, the minimum detection concentrations of P. mirabilis and P. vulgaris in pure bacterial cultures were 6.08 × 102 colony forming units (CFU)/ml and 4.46 × 102 CFU/ml, respectively. Additionally, the minimum detectable number of P. mirabilis and P. vulgaris in meat and milk was 103 CFU/g. In addition, the method can be used to distinguish between strains of P. mirabilis and P. vulgaris within two hours. Overall, it is a sensitive, easy-to-use, and practical test for the identification and classification of Proteus in food.Key words: Proteus mirabilis, Proteus vulgaris, TaqMan Real-Time PCR, food-borne pathogens, food poisoning  相似文献   
119.
The current range and relative abundance of the Egyptian Mongoose Herpestes ichneumon (L.) in Portugal were studied using data obtained through direct field observations, personal communications and answers to enquiries. The present northern limit of its distribution has extended well beyond the Tagus River in most of its Portuguese range, indicating a probable expansion in recent years. A consistent increase in abundance was detected from north to south, latitude being highly correlated with computed indices of Mongoose abundance. The best-fit model for predicting Mongoose relative abundance in the country considers latitude and human population density simultaneously. Altitude is the only environmental variable significantly correlated with the Mongoose abundance once the influence of latitude is discounted. Available information appears to indicate that the Portuguese Mongoose population is increasing, nevertheless research is needed in order to assess the impact of current predator control schemes on local populations.  相似文献   
120.
Spatial heterogeneity is common in aquatic conditions, but few studies have examined the effects of heterogeneous distributions of biological factors on aquatic plants. Spirogyra (Spirogyra arcta) coexists with many submerged macrophytes, such as Ceratophyllum demersum, but no study has examined the effects of heterogeneous distributions of spirogyra on the growth of submerged plants. We grew the submerged plant C. demersum in three homogeneous, aquatic conditions (0, 50 and 100% of the water surface in the container was evenly covered by spirogyra, referred to as ‘control’, ‘50%’ and ‘100%’, respectively) and two patchy conditions (the left half of the water surface in the container was not covered by spirogyra and 50% and 100% of the water surface in the right half of the container was evenly covered by spirogyra, referred to as ‘50%‐patchy’ and ‘100%‐patchy’, respectively). Compared with the control, the 100% treatment greatly decreased the biomass and number of ramets of C. demersum, but the 50% treatment did not. Growth of C. demersum in the left half of the container did not differ significantly between the control and the two heterogeneous treatments (50%‐patchy and 100%‐patchy). In addition, growth of C. demersum in the right half of the container did not differ between the 100% and the 100%‐patchy treatment or between the 50% and the 50%‐patchy treatment. Our results suggest that C. demersum can tolerate shading by spirogyra to a certain extent and that heterogeneous distributions of spirogyra do not affect its growth.  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