全文获取类型
收费全文 | 546篇 |
免费 | 30篇 |
国内免费 | 81篇 |
专业分类
657篇 |
出版年
2023年 | 7篇 |
2022年 | 11篇 |
2021年 | 13篇 |
2020年 | 9篇 |
2019年 | 12篇 |
2018年 | 6篇 |
2016年 | 5篇 |
2015年 | 14篇 |
2014年 | 13篇 |
2013年 | 17篇 |
2012年 | 37篇 |
2011年 | 19篇 |
2010年 | 27篇 |
2009年 | 30篇 |
2008年 | 23篇 |
2007年 | 32篇 |
2006年 | 22篇 |
2005年 | 25篇 |
2004年 | 12篇 |
2003年 | 6篇 |
2002年 | 11篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 11篇 |
1998年 | 9篇 |
1997年 | 6篇 |
1996年 | 11篇 |
1995年 | 4篇 |
1994年 | 5篇 |
1991年 | 3篇 |
1988年 | 2篇 |
1987年 | 6篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1959年 | 17篇 |
1958年 | 30篇 |
1957年 | 13篇 |
1956年 | 15篇 |
1955年 | 21篇 |
1954年 | 19篇 |
1953年 | 26篇 |
1952年 | 19篇 |
1951年 | 15篇 |
1950年 | 19篇 |
排序方式: 共有657条查询结果,搜索用时 15 毫秒
101.
Lerner AG Upton JP Praveen PV Ghosh R Nakagawa Y Igbaria A Shen S Nguyen V Backes BJ Heiman M Heintz N Greengard P Hui S Tang Q Trusina A Oakes SA Papa FR 《Cell metabolism》2012,16(2):250-264
When unfolded proteins accumulate to irremediably high levels within the endoplasmic reticulum (ER), intracellular signaling pathways called the unfolded protein response (UPR) become hyperactivated to?cause programmed cell death. We discovered that?thioredoxin-interacting protein (TXNIP) is?a critical node in this "terminal UPR." TXNIP becomes rapidly induced by IRE1α, an ER bifunctional kinase/endoribonuclease (RNase). Hyperactivated IRE1α increases TXNIP mRNA stability by reducing levels of a TXNIP destabilizing microRNA, miR-17. In turn, elevated TXNIP protein activates the NLRP3 inflammasome, causing procaspase-1 cleavage and interleukin 1β (IL-1β) secretion. Txnip gene deletion reduces pancreatic β cell death during ER stress and suppresses diabetes caused by proinsulin misfolding in the Akita mouse. Finally, small molecule?IRE1α RNase inhibitors suppress TXNIP production to block IL-1β secretion. In summary, the IRE1α-TXNIP pathway is used in the terminal UPR to promote sterile inflammation and programmed cell death and may be targeted to develop effective treatments for cell degenerative diseases. 相似文献
102.
目的 分析妊娠足月前妇女阴道微生态失衡状况.方法 选择孕12 ~ 37周健康无症状单胎妊娠期妇女1 900例,取其阴道分泌物,选用阴道pH、阴道清洁度、过氧化氢浓度(H2O2)、白细胞酯酶(LE)和唾液酸苷酶(SnaSe)等指标对阴道微生态失衡进行评价.结果 妊娠足月前妇女阴道pH为3.80±0.23,阴道微生态失衡发生率为50%,阴道分泌物检查清洁度Ⅲ~ Ⅳ不正常者980例,乳酸菌均阴性,H2O2阳性为53%,H2O2+LE均阳性为14%,H2O2+LE+ SnaSe均阳性+显微镜检出线索细胞妇女为10%,H2O2+LE均阳性+涂片镜检出酵母样真菌孢子妇女为19%,H2O2+LE均阳性+涂片镜检出滴虫妇女为2%.结论 妊娠足月前妇女阴道微生态失衡发生率50%. 相似文献
103.
Group A human rotavirus genomics: evidence that gene constellations are influenced by viral protein interactions 下载免费PDF全文
Heiman EM McDonald SM Barro M Taraporewala ZF Bar-Magen T Patton JT 《Journal of virology》2008,82(22):11106-11116
Group A human rotaviruses (HRVs) are the major cause of severe viral gastroenteritis in infants and young children. To gain insight into the level of genetic variation among HRVs, we determined the genome sequences for 10 strains belonging to different VP7 serotypes (G types). The HRVs chosen for this study, D, DS-1, P, ST3, IAL28, Se584, 69M, WI61, A64, and L26, were isolated from infected persons and adapted to cell culture to use as serotype references. Our sequencing results revealed that most of the individual proteins from each HRV belong to one of three genotypes (1, 2, or 3) based on their similarities to proteins of genogroup strains (Wa, DS-1, or AU-1, respectively). Strains D, P, ST3, IAL28, and WI61 encode genotype 1 (Wa-like) proteins, whereas strains DS-1 and 69M encode genotype 2 (DS-1-like) proteins. Of the 10 HRVs sequenced, 3 of them (Se584, A64, and L26) encode proteins belonging to more than one genotype, indicating that they are intergenogroup reassortants. We used amino acid sequence alignments to identify residues that distinguish proteins belonging to HRV genotype 1, 2, or 3. These genotype-specific changes cluster in definitive regions within each viral protein, many of which are sites of known protein-protein interactions. For the intermediate viral capsid protein (VP6), the changes map onto the atomic structure at the VP2-VP6, VP4-VP6, and VP7-VP6 interfaces. The results of this study provide evidence that group A HRV gene constellations exist and may be influenced by interactions among viral proteins during replication. 相似文献
104.
描述了采自中国四川的剑花蟹蛛Xysticus sicus Fox,1937,其雄性系首次发现。标本保存于河北大学博物馆。 相似文献
105.
Le MT Wertheim HF Nguyen HD Taylor W Hoang PV Vuong CD Nguyen HL Nguyen HH Nguyen TQ Nguyen TV Van TD Ngoc BT Bui TN Nguyen BG Nguyen LT Luong ST Phan PH Pham HV Nguyen T Fox A Nguyen CV Do HQ Crusat M Farrar J Nguyen HT de Jong MD Horby P 《PloS one》2008,3(10):e3339
Background
Prior to 2007, highly pathogenic avian influenza (HPAI) H5N1 viruses isolated from poultry and humans in Vietnam were consistently reported to be clade 1 viruses, susceptible to oseltamivir but resistant to amantadine. Here we describe the re-emergence of human HPAI H5N1 virus infections in Vietnam in 2007 and the characteristics of the isolated viruses.Methods and Findings
Respiratory specimens from patients suspected to be infected with avian influenza in 2007 were screened by influenza and H5 subtype specific polymerase chain reaction. Isolated H5N1 strains were further characterized by genome sequencing and drug susceptibility testing. Eleven poultry outbreak isolates from 2007 were included in the sequence analysis. Eight patients, all of them from northern Vietnam, were diagnosed with H5N1 in 2007 and five of them died. Phylogenetic analysis of H5N1 viruses isolated from humans and poultry in 2007 showed that clade 2.3.4 H5N1 viruses replaced clade 1 viruses in northern Vietnam. Four human H5N1 strains had eight-fold reduced in-vitro susceptibility to oseltamivir as compared to clade 1 viruses. In two poultry isolates the I117V mutation was found in the neuraminidase gene, which is associated with reduced susceptibility to oseltamivir. No mutations in the M2 gene conferring amantadine resistance were found.Conclusion
In 2007, H5N1 clade 2.3.4 viruses replaced clade 1 viruses in northern Vietnam and were susceptible to amantadine but showed reduced susceptibility to oseltamivir. Combination antiviral therapy with oseltamivir and amantadine for human cases in Vietnam is recommended. 相似文献106.
本文综述了植物大环寡肽(cycbtides)的研究进展,列举出迄今已报道的40多个植物大环寡肽,着重介绍了这类活性物质的生源、生物活性和结构特征。 相似文献
107.
This work presents the mitochondrial DNA molecular organization of the control region (CR) of South American camelids. Sequencing of five individuals each of guanaco, llama, alpaca and vicuna species showed that this region spans 1060 bp including three conserved sequence blocks (CSB I–III) adjacent to the tRNAPhe gene, a conserved central domain and one extended termination‐associated sequence in the 3′ domain of the CR close to the tRNAPro gene. A repeated array formed by three units of 26 bp was detected between CSB I and II. Alignment of the CR sequences from the four species shows a 337‐bp segment that includes most of the nucleotide variability with 10 polymorphic sites. We suggest the use of this segment as a molecular marker to infer data on camelid genetic relationships and population diversity studies. 相似文献
108.
应用XTT法检测白细胞介素—Ⅱ的生物学活性 总被引:3,自引:0,他引:3
应用XTT比色法检测IL-2的生物学活性并与MTT法和^3H掺入法进行比较,结果XTT法较上述方法简便易行,结果稳定,重复性好。 相似文献
109.
110.