全文获取类型
收费全文 | 866篇 |
免费 | 42篇 |
国内免费 | 4篇 |
专业分类
912篇 |
出版年
2024年 | 3篇 |
2023年 | 14篇 |
2022年 | 29篇 |
2021年 | 52篇 |
2020年 | 25篇 |
2019年 | 31篇 |
2018年 | 33篇 |
2017年 | 25篇 |
2016年 | 33篇 |
2015年 | 41篇 |
2014年 | 58篇 |
2013年 | 77篇 |
2012年 | 88篇 |
2011年 | 73篇 |
2010年 | 47篇 |
2009年 | 40篇 |
2008年 | 50篇 |
2007年 | 36篇 |
2006年 | 31篇 |
2005年 | 27篇 |
2004年 | 21篇 |
2003年 | 23篇 |
2002年 | 12篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 2篇 |
1998年 | 9篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1980年 | 1篇 |
1978年 | 1篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1953年 | 2篇 |
排序方式: 共有912条查询结果,搜索用时 15 毫秒
751.
Lei Cai DaHe Zhao Jing Hou JinHua Wu ShuangFeng Cai Priya Dassarma Hua Xiang 《中国科学:生命科学英文版》2012,55(5):404-414
Halophilic archaea (haloarchaea) inhabit hypersaline environments, tolerating extreme salinity, low oxygen and nutrient availability, and in some cases, high pH (soda lakes) and irradiation (saltern ponds). Membrane-associated proteins of haloarchaea, such as surface layer (S-layer) proteins, transporters, retinal proteins, and internal organellar membrane proteins including intracellular gas vesicle proteins and those associated with polyhydroxyalkanoate (PHA) granules, contribute greatly to their environmental adaptations. This review focuses on these haloarchaeal cellular and organellar membrane-associated proteins, and provides insight into their physiological significance and biotechnological potential. 相似文献
752.
The topically applied fluorides are efficacious in both prevention against caries attack and inhibition of virulent bacteria. The purpose of this clinical trial was to assess the fluoride concentration in saliva before and after 38% SDF, 5% NaF and 1.23% ApF gel application on enamel and duration of its availability at different time intervals. The present randomized clinical trial was conducted among 60 healthy children aged between 6-12 years where at baseline the participants were instructed to spit for 2 min in sterile containers and the first saliva sample (S1) was taken. The participants were then randomly allocated into 3 different groups in which 38% Silver diamine fluoride, 5% Sodium fluoride and 1.23% ApF gel were applied respectively. The second saliva sample (S2) was collected after 5 min and patients were called after 1 hour for third saliva sample collection. The fluoride concentration was measured in the salivary samples. ANOVA test was used for evaluation and chi square t test was conducted for comparison of 3 groups. The fluoride concentration is comparatively slightly higher for the group receiving SDF than NaF and ApF at baseline, 5 min and 1 hour time interval but is not statistically significant. The mean scores of Fluoride concentration of the three groups were statistically significant at 5 min (F=63.556, p<0.0005) and 1 hour time interval (F=17.577, p<0.0005). Slightly increased salivary fluoride retention was observed post SDF application at 5min and 1 hour time interval when compared to Na F and ApF gel application. The present trial also concluded that topical fluoride application increases fluoride bioavailability in saliva thereby increasing tooth remineralization. 相似文献
753.
Constanze Schmidt Felix Wiedmann Frank Tristram Priya Anand Wolfgang Wenzel Patrick Lugenbiel Patrick A. Schweizer Hugo A. Katus Dierk Thomas 《Life sciences》2014
Aims
Effective management of atrial fibrillation (AF) often remains an unmet need. Cardiac two-pore-domain K+ (K2P) channels are implicated in action potential regulation, and their inhibition has been proposed as a novel antiarrhythmic strategy. K2P2.1 (TREK-1) channels are expressed in the human heart. This study was designed to identify and functionally express porcine K2P2.1 channels. In addition, we sought to analyze cardiac expression and AF-associated K2P2.1 remodeling in a clinically relevant porcine AF model.Main methods
Three pK2P2.1 isoforms were identified and amplified. Currents were recorded using voltage clamp electrophysiology in the Xenopus oocyte expression system. K2P2.1 remodeling was studied by quantitative real time PCR and Western blot in domestic pigs during AF induced by atrial burst pacing.Key findings
Human and porcine K2P2.1 proteins share 99% identity. Residues involved in phosphorylation or glycosylation are conserved. Porcine K2P2.1 channels carried outwardly rectifying K+ currents similar to their human counterparts. In pigs, K2P2.1 was expressed ubiquitously in the heart with predominance in the atrial tissue. AF was associated with time-dependent reduction of K2P2.1 protein in the RA by 70% (7 days of AF) and 80% (21 days of AF) compared to control animals in sinus rhythm. K2P2.1 expression in the left atrium, AV node, and ventricles was not affected by AF.Significance
Similarities between porcine and human K2P2.1 channels indicate that the pig may represent a valid model for mechanistic and preclinical studies. AF-related atrial K2P2.1 remodeling has potential implications for arrhythmia maintenance and antiarrhythmic therapy. 相似文献754.
Arman A. Bashirova Enrique Martin-Gayo Des C. Jones Ying Qi Richard Apps Xiaojiang Gao Patrick S. Burke Craig J. Taylor Jerome Rogich Steven Wolinsky Jay H. Bream Priya Duggal Shehnaz Hussain Jeremy Martinson Amy Weintrob Gregory D. Kirk Jacques Fellay Susan P. Buchbinder James J. Goedert Steven G. Deeks Florencia Pereyra John Trowsdale Mathias Lichterfeld Amalio Telenti Bruce D. Walker Rachel L. Allen Mary Carrington Xu G. Yu 《PLoS genetics》2014,10(3)
Natural progression of HIV-1 infection depends on genetic variation in the human major histocompatibility complex (MHC) class I locus, and the CD8+ T cell response is thought to be a primary mechanism of this effect. However, polymorphism within the MHC may also alter innate immune activity against human immunodeficiency virus type 1 (HIV-1) by changing interactions of human leukocyte antigen (HLA) class I molecules with leukocyte immunoglobulin-like receptors (LILR), a group of immunoregulatory receptors mainly expressed on myelomonocytic cells including dendritic cells (DCs). We used previously characterized HLA allotype-specific binding capacities of LILRB1 and LILRB2 as well as data from a large cohort of HIV-1-infected individuals (N = 5126) to test whether LILR-HLA class I interactions influence viral load in HIV-1 infection. Our analyses in persons of European descent, the largest ethnic group examined, show that the effect of HLA-B alleles on HIV-1 control correlates with the binding strength between corresponding HLA-B allotypes and LILRB2 (p = 10−2). Moreover, overall binding strength of LILRB2 to classical HLA class I allotypes, defined by the HLA-A/B/C genotypes in each patient, positively associates with viral replication in the absence of therapy in patients of both European (p = 10−11–10−9) and African (p = 10−5–10−3) descent. This effect appears to be driven by variations in LILRB2 binding affinities to HLA-B and is independent of individual class I allelic effects that are not related to the LILRB2 function. Correspondingly, in vitro experiments suggest that strong LILRB2-HLA binding negatively affects antigen-presenting properties of DCs. Thus, we propose an impact of LILRB2 on HIV-1 disease outcomes through altered regulation of DCs by LILRB2-HLA engagement. 相似文献
755.
Jrmie Prvost Jonathan Richard Romain Gasser Shilei Ding Clment Fage Sai Priya Anand Damien Adam Natasha Gupta Vergara Alexandra Tauzin Mehdi Benlarbi Shang Yu Gong Guillaume Goyette Anik Priv Sandrine Moreira Hugues Charest Michel Roger Walther Mothes Marzena Pazgier Emmanuelle Brochiero Guy Boivin Cameron F. Abrams Arne Schn Andrs Finzi 《The Journal of biological chemistry》2021,297(4)
The seasonal nature of outbreaks of respiratory viral infections with increased transmission during low temperatures has been well established. Accordingly, temperature has been suggested to play a role on the viability and transmissibility of SARS-CoV-2, the virus responsible for the COVID-19 pandemic. The receptor-binding domain (RBD) of the Spike glycoprotein is known to bind to its host receptor angiotensin-converting enzyme 2 (ACE2) to initiate viral fusion. Using biochemical, biophysical, and functional assays to dissect the effect of temperature on the receptor–Spike interaction, we observed a significant and stepwise increase in RBD-ACE2 affinity at low temperatures, resulting in slower dissociation kinetics. This translated into enhanced interaction of the full Spike glycoprotein with the ACE2 receptor and higher viral attachment at low temperatures. Interestingly, the RBD N501Y mutation, present in emerging variants of concern (VOCs) that are fueling the pandemic worldwide (including the B.1.1.7 (α) lineage), bypassed this requirement. This data suggests that the acquisition of N501Y reflects an adaptation to warmer climates, a hypothesis that remains to be tested. 相似文献
756.
757.
Priyanka James Vipin Anithottam Mathai Silpa Shajikumar Priya Antony Pereppadan Parvathi Sudha Raghunath Keshavachandran Puthiyaveetil Abdulla Nazeem 《Bioinformation》2013,9(18):941-943
Medicinal plants and plant derived molecules are widely used in traditional cultures all over the world and they are becoming
large popular among biomedical researchers and pharmaceutical companies as a natural alternative to synthetic medicine.
Information related to medicinal plants and herbal drugs accumulated over the ages are scattered and unstructured which make it
prudent to develop a curated database for medicinal plants. The Antidiabetic and Anticancer Medicinal Plants Database
(DIACAN) aims to collect and provide an integrated platform for plants and phytochemiclas having antidiabetic or anticancer activity.
Availability
http://www.kaubic.in/diacan 相似文献758.
Vladimir Ilievski Yale Cho Priya Katwala Heriberto Rodriguez Margaret Tulowiecka David Kurian Lara Leoni John W. Christman Terry G. Unterman Keiko Watanabe 《PloS one》2015,10(8)
Background
Results from epidemiological studies indicate a close association between periodontitis and type 2 diabetes mellitus. However, the mechanism linking periodontitis to glucose intolerance (GI) and insulin resistance (IR) is unknown. We therefore tested the hypothesis that periodontitis induces the development of GI/IR through a liver Toll-like receptor 4 (TLR4) dependent mechanism.Methods
TLR4 chimeric mice were developed by bone marrow transplantation using green fluorescent protein expressing TLR4WT mouse (GFPWT) as donor and TLR4 WT or TLR4-/- as recipient mice (GFPWT:WT and GFPWT:KO chimeras respectively). These chimeras were subjected to experimental chronic periodontitis induced by repeated applications of LPS to the gingival sulci for 18 weeks. The levels of GI/IR were monitored and plasma cytokines and LPS were determined at 18 weeks when differences in glucose tolerance were most apparent. Cytokine gene expression was measured in liver tissue by qPCR.Results
Alveolar bone loss was significantly greater in GFPWT:WT chimeras treated with LPS compared with chimeras treated with PBS or GFPWT:KO chimeras. However, the degree of gingival inflammation was similar between GFPWT:WT and GFPWT:KO mice with LPS application. Severe GI/IR occurred in GFPWT:WT chimeras but not in the GFPWT:KO chimeras that were subjected to 18 weeks of LPS. Serum LPS was detected only in animals to which LPS was applied and the level was similar in GFPWT:WT and GFPWT:KO mice at the 18 week time point. Surprisingly, there was no significant difference in the plasma levels of IL1β, IL6 and TNFα at 18 weeks in spite of the severe GI/IR in the GFPWT:WT chimeras with LPS application. Also, no difference in the expression of TNFα or IL6 mRNA was detected in the liver of GFPWT:WT vs GFPWT:KO mice. In contrast, liver IL1β expression was significantly greater in GFPWT:WT chimeras compared to GFPWT:KO chimeras treated with LPS.Conclusion
We observed that GFPWT:WT, but not GFPWT:KO chimeras, treated with LPS developed GI/IR despite similar degrees of gingival inflammation, circulating cytokine levels, and LPS concentrations. We conclude that LPS from periodontitis sites has a pivotal role in triggering the development of GI/IR through a mechanism that involves TLR4 expression by resident macrophages/Kupffer cells in the liver. 相似文献759.
Wellington Muchero Jianjun Guo Stephen P DiFazio Jin-Gui Chen Priya Ranjan Gancho T Slavov Lee E Gunter Sara Jawdy Anthony C Bryan Robert Sykes Angela Ziebell Jaroslav Kláp?tě Ilga Porth Oleksandr Skyba Faride Unda Yousry A El-Kassaby Carl J Douglas Shawn D Mansfield Joel Martin Wendy Schackwitz Luke M Evans Olaf Czarnecki Gerald A Tuskan 《BMC genomics》2015,16(1)
760.
Willy Yee Janushree Nanda Kumar Priya Devi Muthusamy 《Indian journal of microbiology》2018,58(1):109-113
2-mercaptoethanol (2-ME), alongside polyvinylpyrrolidone is commonly used in plant DNA extractions to deal with polyphenols, which could interfere with extraction and downstream applications. 2-ME is also commonly used to denature proteins and nucleases, especially RNAses. On the contrary, we found that the presence of 2-ME in lysis buffer interfered with DNA extraction from 12 strains of freshwater microalgae, resulting in DNA with poor integrity. We also found that the TNES-urea buffer, commonly used for preservation and DNA extraction from fish, appears as effective as the SDS and CTAB buffer for some microalgae strains. Results from our study suggests that the inclusion of 2-ME in DNA extraction protocols may be detrimental for isolation of good quality DNA from freshwater microalgae, and therefore recommend eliminating it or testing varying concentrations of 2-ME when developing species-specific extraction protocols for microalgae. 相似文献