全文获取类型
收费全文 | 240篇 |
免费 | 15篇 |
国内免费 | 26篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 16篇 |
2020年 | 7篇 |
2019年 | 15篇 |
2018年 | 13篇 |
2017年 | 13篇 |
2016年 | 13篇 |
2015年 | 26篇 |
2014年 | 17篇 |
2013年 | 23篇 |
2012年 | 16篇 |
2011年 | 10篇 |
2010年 | 16篇 |
2009年 | 3篇 |
2008年 | 7篇 |
2007年 | 12篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2003年 | 2篇 |
2002年 | 6篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1999年 | 7篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1983年 | 1篇 |
排序方式: 共有281条查询结果,搜索用时 46 毫秒
61.
Peck Shen Mun Hua Nong Ting Teng Aik Ong Chew Ming Wong Kwan Hong Ng Yip Boon Chong 《PloS one》2015,10(6)
This paper investigates the dielectric properties of urine in normal subjects and subjects with chronic kidney disease (CKD) at microwave frequency of between 0.2 GHz and 50 GHz. The measurements were conducted using an open-ended coaxial probe at room temperature (25°C), at 30°C and at human body temperature (37°C). There were statistically significant differences in the dielectric properties of the CKD subjects compared to those of the normal subjects. Statistically significant differences in dielectric properties were observed across the temperatures for normal subjects and CKD subjects. Pearson correlation test showed the significant correlation between proteinuria and dielectric properties. The experimental data closely matched the single-pole Debye model. The relaxation dispersion and relaxation time increased with the proteinuria level, while decreasing with the temperature. As for static conductivity, it increased with proteinuria level and temperature. 相似文献
62.
Yuanda Xu Xilong Deng Yun Han Lixin Zhou Weiqun He Sibei Chen Lingbo Nong Huang Huang Yan Zhang Tieou Yu Yimin Li Xiaoqing Liu 《PloS one》2015,10(8)
Background
Patients with H7N9 avian flu concurrent with severe acute respiratory distress syndrome (ARDS) usually have a poor clinical outcome. Prone position ventilation (PPV) has been shown to improve the prognosis of patients with severe ARDS. This study explored the effects of PPV on the respiratory and circulatory mechanics of H7N9-infected patients with severe ARDS.Methods
Individuals admitted to four hospitals designated for H7N9 patients in Guangdong province were treated with PPV, and their clinical data were recorded before and after receiving PPV.Results
Six of 20 critically ill patients in the ICU received PPV. After treatment with 35 PPV sessions, the oxygenation index (OI) values of the six patients when measured post-PPV and post-supine position ventilation (SPV) were significantly higher than those measured pre-PPV (P < 0.05).The six patients showed no significant differences in their values for respiratory rate (RR), peak inspiratory pressure (PIP), tidal volume (TV) or arterial partial pressure of carbon dioxide (PaCO2) when compared pre-PPV, post-PPV, and post-SPV. Additionally, there were no significant differences in the mean values for arterial pressure (MAP), cardiac index (CI), central venous pressure (CVP), heart rate (HR), lactic acid (LAC) levels or the doses of norepinephrine (NE) administered when compared pre-PPV, post-PPV, and post-SPV.Conclusion
PPV provided improved oxygenation that was sustained after returning to a supine position, and resulted in decreased carbon dioxide retention. PPV can thus serve as an alternative lung protective ventilation strategy for use in patients with H7N9 avian flu concurrent with severe ARDS. 相似文献63.
64.
Junxiu Nong Kexin Kang Qiaoni Shi Xuechen Zhu Qinghua Tao Ye-Guang Chen 《The Journal of cell biology》2021,220(4)
In Wnt/β-catenin signaling, the β-catenin protein level is deliberately controlled by the assembly of the multiprotein β-catenin destruction complex composed of Axin, adenomatous polyposis coli (APC), glycogen synthase kinase 3β (GSK3β), casein kinase 1α (CK1α), and others. Here we provide compelling evidence that formation of the destruction complex is driven by protein liquid–liquid phase separation (LLPS) of Axin. An intrinsically disordered region in Axin plays an important role in driving its LLPS. Phase-separated Axin provides a scaffold for recruiting GSK3β, CK1α, and β-catenin. APC also undergoes LLPS in vitro and enhances the size and dynamics of Axin phase droplets. The LLPS-driven assembly of the destruction complex facilitates β-catenin phosphorylation by GSK3β and is critical for the regulation of β-catenin protein stability and thus Wnt/β-catenin signaling. 相似文献
65.
目的:探讨烟雾病的发生与自身免疫性疾病是否存在一定的联系。方法:对402例烟雾病抗核抗体谱检测结果进行回顾性分析。结果:402例烟雾病确诊病例中,有112位患者抗核抗体谱检测结果中存在阳性结果,阳性率为27.86%。其中,抗dsDNA、抗CB、抗Sm、抗SS-A、抗SS-B、抗Jo-1、抗RO-52、抗ScL-70、抗RIB、抗PM-sd、抗nRNP、抗PCNA、抗Nuc、抗HI、抗M2抗体在阳性病例中所占百分比分别为16.07%、1.79%、5.36%、17.86%、7.14%、5.36%、13.39%、5.36%、7.14%、4.46%、2.68%、11.61%、6.25%、8.93%和8.04%。结论:烟雾病患者中抗核抗体阳性率较高,自身免疫性疾病可能是烟雾病发生的重要诱因之一。 相似文献
66.
【目的】从南海柳珊瑚共附生放线菌的次生代谢产物中寻找具有抗菌和抗附着活性的先导化合物。【方法】应用化学与生物活性相结合的筛选方法,从柳珊瑚共附生微生物中筛选获得代谢产物丰富且具有生物活性的目标菌株并通过大发酵提取浸膏,利用硅胶柱色谱、凝胶柱色谱和高效液相色谱等方法对发酵产物进行分离、纯化,运用波谱解析鉴定化合物的结构。【结果】从采自海南三亚的柳珊瑚(Muricella flexuosa)样品中分离到一株放线菌SCSGAA0009,鉴定为链霉属Streptomycessp.,从其改良ISP2发酵液中分离到新化合物N-(2-(1H-indol-3-yl)ethyl)propionamide(1)和已知化合物phenazine-1-carboxylic acid(2),其中化合物2对大肠杆菌和海洋细菌假单胞菌(Pseudoaltermonas piscida)具有较好抗菌活性,且有强抗草苔虫(Bugulaneritina)幼虫附着活性。【结论】首次从柳珊瑚共附生放线菌的次生代谢产物中获得新的生物碱化合物1,首次报道化合物2的抗海洋细菌活性和抗附着活性;从南海柳珊瑚共附生微生物的次生代谢产物中可以得到新化合物和活性化合物,这一来源的微生物资源值得深入研究。 相似文献
67.
Deying Yang Yongjun Ren Yan Fu Yue Xie Huaming Nie Xiang Nong Xiaobin Gu Shuxian Wang Xuerong Peng Guangyou Yang 《The Korean journal of parasitology》2013,51(4):449-452
Taenia pisiformis is one of the most important parasites of canines and rabbits. T. pisiformis cysticercus (the larval stage) causes severe damage to rabbit breeding, which results in huge economic losses. In this study, the genetic variation of T. pisiformis was determined in Sichuan Province, China. Fragments of the mitochondrial cytochrome b (cytb) (922 bp) gene were amplified in 53 isolates from 8 regions of T. pisiformis. Overall, 12 haplotypes were found in these 53 cytb sequences. Molecular genetic variations showed 98.4% genetic variation derived from intra-region. FST and Nm values suggested that 53 isolates were not genetically differentiated and had low levels of genetic diversity. Neutrality indices of the cytb sequences showed the evolution of T. pisiformis followed a neutral mode. Phylogenetic analysis revealed no correlation between phylogeny and geographic distribution. These findings indicate that 53 isolates of T. pisiformis keep a low genetic variation, which provide useful knowledge for monitoring changes in parasite populations for future control strategies. 相似文献
68.
Yong Liang Chen Chun Ling Xu Xue Nong Xu Hui Xie Bao Xin Zhang Hou Guo Qin Wan Qin Zhou Dun Song Li 《Experimental & applied acarology》2013,60(3):289-298
Predation and predatory behavior of Blattisocius dolichus on Radopholus similis were tested both in experimental arenas and on potted plants. Predation occurred in all active stages of B. dolichus. Blattisocius dolichus preferred live R. similis when offered together with Caneorhabditis elegans and dead R. similis in a choice test. Consumption rate was affected by temperature, prey density and duration of starvation. Maximum consumption rates were observed at 25 °C, for both adult males and females after being starved for 96 and 72 h, respectively. Consumption rate increased with increasing prey density until satiation was reached, when the predator–prey ratio was 1:250 for both male and female predators. Anthurium andraeanum seedlings, artificially infested with R. similis (1,000 per pot), were used to evaluate the biological control efficiency of B. dolichus. The nematode density decreased by 66 % 10 days after a release of 500 mites per pot. 相似文献
69.
Structure, function, and regulation of the aldouronate utilization gene cluster from Paenibacillus sp. strain JDR-2
下载免费PDF全文
![点击此处可从《Journal of bacteriology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Direct bacterial conversion of the hemicellulose fraction of hardwoods and crop residues to biobased products depends upon extracellular depolymerization of methylglucuronoxylan (MeGAXn), followed by assimilation and intracellular conversion of aldouronates and xylooligosaccharides to fermentable xylose. Paenibacillus sp. strain JDR-2, an aggressively xylanolytic bacterium, secretes a multimodular cell-associated GH10 endoxylanase (XynA1) that catalyzes depolymerization of MeGAXn and rapidly assimilates the principal products, β-1,4-xylobiose, β-1,4-xylotriose, and MeGAX3, the aldotetrauronate 4-O-methylglucuronosyl-α-1,2-xylotriose. Genomic libraries derived from this bacterium have now allowed cloning and sequencing of a unique aldouronate utilization gene cluster comprised of genes encoding signal transduction regulatory proteins, ABC transporter proteins, and the enzymes AguA (GH67 α-glucuronidase), XynA2 (GH10 endoxylanase), and XynB (GH43 β-xylosidase/α-arabinofuranosidase). Expression of these genes, as well as xynA1 encoding the secreted GH10 endoxylanase, is induced by growth on MeGAXn and repressed by glucose. Sequences in the yesN, lplA, and xynA2 genes within the cluster and in the distal xynA1 gene show significant similarity to catabolite responsive element (cre) defined in Bacillus subtilis for recognition of the catabolite control protein (CcpA) and consequential repression of catabolic regulons. The aldouronate utilization gene cluster in Paenibacillus sp. strain JDR-2 operates as a regulon, coregulated with the expression of xynA1, conferring the ability for efficient assimilation and catabolism of the aldouronate product generated by a multimodular cell surface-anchored GH10 endoxylanase. This cluster offers a desirable metabolic potential for bacterial conversion of hemicellulose fractions of hardwood and crop residues to biobased products. 相似文献
70.
Variable-number tandem repeats (VNTRs) have been identified in populations of Pasteuria ramosa, a castrating endobacterium of Daphnia species. The allelic polymorphisms at 14 loci in laboratory and geographically diverse soil samples showed that VNTRs may serve as biomarkers for the genetic characterization of P. ramosa isolates. 相似文献