全文获取类型
收费全文 | 965篇 |
免费 | 91篇 |
出版年
2023年 | 5篇 |
2022年 | 12篇 |
2021年 | 22篇 |
2020年 | 12篇 |
2019年 | 16篇 |
2018年 | 16篇 |
2017年 | 7篇 |
2016年 | 29篇 |
2015年 | 46篇 |
2014年 | 65篇 |
2013年 | 63篇 |
2012年 | 90篇 |
2011年 | 88篇 |
2010年 | 40篇 |
2009年 | 44篇 |
2008年 | 52篇 |
2007年 | 53篇 |
2006年 | 51篇 |
2005年 | 40篇 |
2004年 | 42篇 |
2003年 | 41篇 |
2002年 | 39篇 |
2001年 | 9篇 |
2000年 | 4篇 |
1999年 | 6篇 |
1998年 | 11篇 |
1997年 | 13篇 |
1996年 | 15篇 |
1995年 | 15篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 4篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 4篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 6篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 10篇 |
1979年 | 4篇 |
1976年 | 2篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1972年 | 3篇 |
1971年 | 1篇 |
排序方式: 共有1056条查询结果,搜索用时 15 毫秒
101.
102.
Background
Multiple alignment of homologous DNA sequences is of great interest to biologists since it provides a window into evolutionary processes. At present, the accuracy of whole-genome multiple alignments, particularly in noncoding regions, has not been thoroughly evaluated. 相似文献103.
104.
Limited influence of local and landscape factors on finescale gene flow in two pond‐breeding amphibians
下载免费PDF全文
![点击此处可从《Molecular ecology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Stephanie S. Coster Kimberly J. Babbitt Andrew Cooper Adrienne I. Kovach 《Molecular ecology》2015,24(4):742-758
Dispersal and gene flow within animal populations are influenced by the composition and configuration of the landscape. In this study, we evaluated hypotheses about the impact of natural and anthropogenic factors on genetic differentiation in two amphibian species, the spotted salamander (Ambystoma maculatum) and the wood frog (Lithobates sylvaticus) in a commercial forest in central Maine. We conducted this analysis at two scales: a local level, focused on factors measured at each breeding pond, and a landscape level, focused on factors measured between ponds. We investigated the effects of a number of environmental factors in six categories including Productivity, Physical, Land Composition, Land Configuration, Isolation and Location. Embryos were sampled from 56 spotted salamander breeding ponds and 39 wood frog breeding ponds. We used a hierarchical Bayesian approach in the program GESTE at each breeding pond and a random forest algorithm in conjunction with a network analysis between the ponds. We found overall high genetic connectivity across distances up to 17 km for both species and a limited effect of natural and anthropogenic factors on gene flow. We found the null models best explained patterns of genetic differentiation at a local level and found several factors at the landscape level that weakly influenced gene flow. This research indicates multiscale investigations that incorporate local and landscape factors are valuable for understanding patterns of gene flow. Our findings suggest that dispersal rates in this system are high enough to minimize genetic structuring and that current forestry practices do not significantly impede dispersal. 相似文献
105.
106.
107.
Shi Y O'Connor SP Sitkoff D Zhang J Shi M Bisaha SN Wang Y Li C Ruan Z Lawrence RM Klei HE Kish K Liu EC Seiler SM Schweizer L Steinbacher TE Schumacher WA Robl JA Macor JE Atwal KS Stein PD 《Bioorganic & medicinal chemistry letters》2011,21(24):7516-7521
The design, synthesis and SAR of a novel class of valerolactam-based arylsulfonamides as potent and selective FXa inhibitors is reported. The arylsulfonamide–valerolactam scaffold was derived based on the proposed bioisosterism to the arylcyanoguanidine-caprolactam core in known FXa inhibitors. The SAR study led to compound 46 as the most potent FXa inhibitor in this series, with an IC50 of 7 nM and EC2×PT of 1.7 μM. The X-ray structure of compound 40 bound to FXa shows that the sulfonamide–valerolactam scaffold anchors the aryl group in the S1 and the novel acylcytisine pharmacophore in the S4 pockets. 相似文献
108.
Chow R Lin A Tonai R Bolanos R Connor C Mendoza A Heminger R Chow M Ho E Kang J Gindy L Fu C Rao A Gau JF Wang BC Klich I Ratajczak J Ratajczak M Petz LD 《Cytotherapy》2011,13(9):1105-1119
Background aimsLimited cell dose has hampered the use of cord blood transplantation (CBT) in adults. One method of minimizing nucleated cell loss in cord blood (CB) processing is to deplete or reduce plasma but not red blood cells - plasma depletion/reduction (PDR).MethodsThe nucleated cell loss of PDR was studied, and determined to be less than 0.1% in the discarded supernatant plasma fraction in validation experiments. After testing and archival sampling, the median nucleated cell recovery for PDR processing was 90%, and median CD34+ cell recovery 88%. In a CB bank inventory of 12 339 products with both pre- and post-processing total nucleated cells (TNC), PDR processing resulted in median post-processing TNC recoveries of 90.0% after testing and archival samples removal. Using the same 10 CB units divided into two halves, we compared directly the recovery of PDR against hydroxyethyl starch red cell reduction (RCR) for TNC, CD34+ cells and colony-forming units (CFU-GM, CFU-E, CFU-GEMM and total CFU) after parallel processing. We also compared the loss of very small embryonic-like stem cells (VSEL).ResultsWe demonstrated significantly higher recoveries using PDR for TNC (124%), CD34+ cells (121%), CFU-GM (225%), CFU-GEMM (201%), total CFU (186%) and VSEL (187%). The proportion of high TNC products was compared between 10 912 PDR and 38 819 RCR CB products and found to be 200% higher for products that had TNC ≥150 × 107 (P = 0.0001) for the PDR inventory.ConclusionsOur data indicate that PDR processing of CB provides a significantly more efficient usage of this valuable and scarce resource. 相似文献
109.
Zhao J Wu H Khosravi M Cui H Qian X Kelly JA Kaufman KM Langefeld CD Williams AH Comeau ME Ziegler JT Marion MC Adler A Glenn SB Alarcón-Riquelme ME;BIOLUPUS Network;GENLES Network Pons-Estel BA Harley JB Bae SC Bang SY Cho SK Jacob CO Vyse TJ Niewold TB Gaffney PM Moser KL Kimberly RP Edberg JC Brown EE Alarcon GS Petri MA Ramsey-Goldman R Vilá LM Reveille JD James JA Gilkeson GS Kamen DL Freedman BI Anaya JM Merrill JT Criswell LA Scofield RH Stevens AM Guthridge JM Chang DM Song YW Park JA 《PLoS genetics》2011,7(5):e1002079
Systemic lupus erythematosus (SLE), a complex polygenic autoimmune disease, is associated with increased complement activation. Variants of genes encoding complement regulator factor H (CFH) and five CFH-related proteins (CFHR1-CFHR5) within the chromosome 1q32 locus linked to SLE, have been associated with multiple human diseases and may contribute to dysregulated complement activation predisposing to SLE. We assessed 60 SNPs covering the CFH-CFHRs region for association with SLE in 15,864 case-control subjects derived from four ethnic groups. Significant allelic associations with SLE were detected in European Americans (EA) and African Americans (AA), which could be attributed to an intronic CFH SNP (rs6677604, in intron 11, P
meta = 6.6×10−8, OR = 1.18) and an intergenic SNP between CFHR1 and CFHR4 (rs16840639, P
meta = 2.9×10−7, OR = 1.17) rather than to previously identified disease-associated CFH exonic SNPs, including I62V, Y402H, A474A, and D936E. In addition, allelic association of rs6677604 with SLE was subsequently confirmed in Asians (AS). Haplotype analysis revealed that the underlying causal variant, tagged by rs6677604 and rs16840639, was localized to a ∼146 kb block extending from intron 9 of CFH to downstream of CFHR1. Within this block, the deletion of CFHR3 and CFHR1 (CFHR3-1Δ), a likely causal variant measured using multiplex ligation-dependent probe amplification, was tagged by rs6677604 in EA and AS and rs16840639 in AA, respectively. Deduced from genotypic associations of tag SNPs in EA, AA, and AS, homozygous deletion of CFHR3-1Δ (P
meta = 3.2×10−7, OR = 1.47) conferred a higher risk of SLE than heterozygous deletion (P
meta = 3.5×10−4, OR = 1.14). These results suggested that the CFHR3-1Δ deletion within the SLE-associated block, but not the previously described exonic SNPs of CFH, might contribute to the development of SLE in EA, AA, and AS, providing new insights into the role of complement regulators in the pathogenesis of SLE. 相似文献
110.
Shah AH Abdelzaher AM Phillips M Hernandez R Solo-Gabriele HM Kish J Scorzetti G Fell JW Diaz MR Scott TM Lukasik J Harwood VJ McQuaig S Sinigalliano CD Gidley ML Wanless D Ager A Lui J Stewart JR Plano LR Fleming LE 《Journal of applied microbiology》2011,110(6):1571-1583
Aims: Research into the relationship between pathogens, faecal indicator microbes and environmental factors in beach sand has been limited, yet vital to the understanding of the microbial relationship between sand and the water column and to the improvement of criteria for better human health protection at beaches. The objectives of this study were to evaluate the presence and distribution of pathogens in various zones of beach sand (subtidal, intertidal and supratidal) and to assess their relationship with environmental parameters and indicator microbes at a non‐point source subtropical marine beach. Methods and Results: In this exploratory study in subtropical Miami (Florida, USA), beach sand samples were collected and analysed over the course of 6 days for several pathogens, microbial source tracking markers and indicator microbes. An inverse correlation between moisture content and most indicator microbes was found. Significant associations were identified between some indicator microbes and pathogens (such as nematode larvae and yeasts in the genus Candida), which are from classes of microbes that are rarely evaluated in the context of recreational beach use. Conclusions: Results indicate that indicator microbes may predict the presence of some of the pathogens, in particular helminthes, yeasts and the bacterial pathogen Staphylococcus aureus including methicillin‐resistant forms. Indicator microbes may thus be useful for monitoring beach sand and water quality at non‐point source beaches. Significance and Impact of the Study: The presence of both indicator microbes and pathogens in beach sand provides one possible explanation for human health effects reported at non‐point sources beaches. 相似文献