全文获取类型
收费全文 | 664篇 |
免费 | 17篇 |
国内免费 | 21篇 |
出版年
2023年 | 5篇 |
2022年 | 9篇 |
2021年 | 9篇 |
2020年 | 20篇 |
2019年 | 22篇 |
2018年 | 31篇 |
2017年 | 19篇 |
2016年 | 17篇 |
2015年 | 17篇 |
2014年 | 37篇 |
2013年 | 36篇 |
2012年 | 13篇 |
2011年 | 37篇 |
2010年 | 21篇 |
2009年 | 37篇 |
2008年 | 49篇 |
2007年 | 36篇 |
2006年 | 27篇 |
2005年 | 25篇 |
2004年 | 21篇 |
2003年 | 13篇 |
2002年 | 17篇 |
2001年 | 6篇 |
2000年 | 8篇 |
1999年 | 10篇 |
1998年 | 13篇 |
1997年 | 12篇 |
1996年 | 18篇 |
1995年 | 13篇 |
1994年 | 16篇 |
1993年 | 12篇 |
1992年 | 8篇 |
1991年 | 9篇 |
1990年 | 5篇 |
1989年 | 6篇 |
1988年 | 6篇 |
1987年 | 3篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1963年 | 1篇 |
排序方式: 共有702条查询结果,搜索用时 15 毫秒
61.
Hemei Chen Shasha Liu Huili Yang Yu Mao Chunhui Deng Xiangmin Zhang Pengyuan Yang 《Proteomics》2010,10(5):930-939
In this work, we report the development of a novel enrichment protocol for peptides by using the microspheres composed of Fe3O4@nSiO2 Core and perpendicularly aligned mesoporous SiO2 shell (designated Fe3O4@nSiO2@mSiO2). The Fe3O4@nSiO2@mSiO2 microspheres possess useful magnetic responsivity which makes the process of enrichment fast and convenient. The highly ordered nanoscale pores (2 nm) and high‐surface areas of the microspheres were demonstrated to have good size‐exclusion effect for the adsorption of peptides. An increase of S/N ratio over 100 times could be achieved by using the microspheres to enrich a standard peptide, and the application of the microspheres to enrich universal peptides was performed by using myoglobin tryptic digest solution. The enrichment efficiency of re‐used Fe3O4@nSiO2@mSiO2 microspheres was also studied. Large‐scale enrichment of endogenous peptides in rat brain extract was achieved by the microspheres. Automated nano‐LC‐ESI‐MS/MS was applied to analyze the sample after enrichment, and 60 unique peptides were identified in total. The facile and low‐cost synthesis as well as the convenient and efficient enrichment process of the novel Fe3O4@nSiO2@mSiO2 microspheres makes it a promising candidate for selectively isolation and enrichment of endogenous peptides from complex biological samples. 相似文献
62.
Gabriella A. Papale Paul J. Hanson Victor A. Drover 《Archives of biochemistry and biophysics》2010,496(2):132-6254
The binding of high density lipoprotein (HDL) to scavenger receptor BI (SR-BI) is responsible for whole-body cholesterol disposal via reverse cholesterol transport. The extracellular domain of SR-BI is required for HDL binding and selective uptake of HDL-cholesterol. We identified six highly hydrophobic regions in this domain that may be important for receptor activity and performed site-directed mutagenesis to investigate the importance of these regions in SR-BI-mediated cholesterol transport. Non-conservative mutation of the regions encompassing V67, L140/L142, V164 or V221 reduced hydrophobicity and impaired the ability of SR-BI to bind HDL, mediate selective uptake of HDL-cholesterol, promote cholesterol efflux, and enlarge the cholesterol oxidase-sensitive pool of membrane free cholesterol. In contrast, conservative mutations at V67, V164 or V221 did not affect the hydrophobicity or these cholesterol transport activities. We conclude that the hydrophobicity of N-terminal extracellular regions of SR-BI is critical for cholesterol transport, possibly by mediating receptor-ligand and/or receptor-membrane interactions. 相似文献
63.
Campbell RB 《Bulletin of mathematical biology》2007,69(7):2249-2259
This work studies the coalescent (ancestral pedigree, genealogy) of the entire population. The coalescent structure (topology)
is robust, but selection changes the rate of coalescence (the time between branching events). The change in the rate of coalescence
is not uniform, rather the reduction in the time between branching events is greatest when the coalescent is small (immediately
after the common ancestor is the only member of the coalescent) with little change when the coalescent is large (immediately
preceding when that common ancestor becomes fixed and the size of the coalescent is N). This provides that the reduction in the coalescent time due to selection is much greater than the reduction in the cumulative
size of the coalescent (total number of ancestors of the present population after and including the most recent common ancestor)
due to selection. If Ns≫1, the coalescent and fixation times are approximately equal to
, which is much less than the value N which would result from neutral drift (N rather than the canonical haploid neutral fixation time 2N is the appropriate comparison for the model considered here), in particular, it is 70% less for Ns=10 and 95% less for Ns=100. However, for those values of Ns, and N ranging between 103 and 106, the reduction in the cumulative size of the coalescent of the entire population compared to the neutral case ranges from
17% to 65% (depending on the values of N and s). The coalescent time for two individuals for Ns of 10 and 100 is reduced by approximately 70% and 94%, respectively, compared with the neutral case. Because heterozygosity
is proportional to the coalescent time for two individuals and the number of segregating alleles is proportional to the cumulative
size of the coalescent, selection reduces heterozygosity more than it reduces the number of segregating alleles. 相似文献
64.
Smirnova AS Ferreira-Silva KC Mine KL Andrade-Oliveira V Shulzhenko N Gerbase-DeLima M Morgun A 《Immunogenetics》2007,59(1):93-98
Various single nucleotide polymorphisms (SNPs) have been investigated regarding association with gene expression levels or
human diseases. Although different SNPs within one gene are frequently analyzed individually, it is highly probable that in
the majority of the cases, a precise combination of SNP alleles, i.e., haplotype, determines a functional trait. Methods commonly
used for haplotype determination, involving studies in families, cloning, or somatic cell hybrids, are expensive and time-consuming.
We herein suggest a novel and simple strategy for haplotype determination, involving selective haplotype depletion with a
restriction enzyme, followed by sequencing. We studied 11 LTA gene polymorphisms in 102 Brazilian individuals, and we applied this novel methodology for haplotyping 67 out of 70 LTA heterozygous individuals. We concluded that the method is rapid and efficient, and, as it includes only simple and widespread-used
techniques, it could be used in most of the laboratories without further investment in equipments. The wider usage of haplotyping
could be important to clarify contradictory results frequently observed among studies that focus on a single SNP.
Maria Gerbase-DeLima and Andrey Morgun are co-senior authors. 相似文献
65.
66.
Synthesis and characterization of metal ion imprinted nano-porous polymer for the selective recognition of copper 总被引:1,自引:0,他引:1
Baghel A Boopathi M Singh B Pandey P Mahato TH Gutch PK Sekhar K 《Biosensors & bioelectronics》2007,22(12):3326-3334
Selective recognition of metal ions utilizing metal ion-imprinted polymers (MIIPs) received much importance in diverse fields owing to their high selectivity for the target metal ions. In the present study, a copper ion imprinted polymer was synthesized without an additional complexing ligand or complex with a broad aim to avoid the conventional extra metal ion complexing ligand during the synthesis of MIIP. The complete removal of the copper metal ion from the MIIP was confirmed by AAS and SEM–EDX. SEM image of the MIIP exhibited nano-patterns and it was also found to be entirely different from that of non-imprinted polymer and polymer with copper metal ions. BET surface area analysis revealed more surface area (47.96 m2/g) for the Cu(II)-MIIP than non-imprinted control polymer (41.43 m2/g). TGA result of polymer with copper metal ion indicated more char yield (18.41%) when compared to non-imprinted control polymer (8.3%) and Cu(II)-MIIP (less than 1%). FTIR study confirmed the complexation between Cu(II)-MIIP and Cu(II) metal ion through carbonyl oxygen of acryl amide. The Cu(II)-MIIP exhibited an imprinting efficiency of 2.0 and it was showing 8% interference from a mixture of Zn, Ni and Co ions. A potentiometric ion selective electrode devised with Cu(II)-MIIP showed more potential response for Cu(II) ion than that was fabricated from non-imprinted polymer. 相似文献
67.
We have conducted a preliminary study of tidal and diurnal variations in the distribution of dominant larval and juvenile
fishes in the Chikugo River inlet (Ariake Bay, Kyushu, Japan) to determine whether selective tidal stream transport (STST)
occurs. Larval and juvenile fish were collected from the mesohaline zone of the Chikugo River inlet during spring 2002. Temperature,
salinity, depth, and current velocity were measured. Larval and juvenile abundance were compared among four tidal conditions,
flooding tide, high tide, ebbing tide, and low tide, and between day and night. A total of 12 families, 15 species, and 5,577
individuals were collected. Temperature did not vary significantly with tidal conditions whereas salinity, depth, and current
velocity varied significantly. Salinity also was correlated significantly and positively with depth. The abundance of most
of the fishes was correlated positively and significantly with salinity and depth. Lateolabrax japonicus, Trachidermus fasciatus, Acanthogobius hasta, and other gobiid larvae (Gobiidae spp.) were significantly more abundant during high tide; in contrast, Coilia nasus and Neosalanx reganius were most abundant during low tide. The abundance of most of the fishes was higher during high tides at night than during
the day, indicating the existence of STST, which may be strategically associated with ascending progress to upstream nursery
areas. 相似文献
68.
Lundström P Teilum K Carstensen T Bezsonova I Wiesner S Hansen DF Religa TL Akke M Kay LE 《Journal of biomolecular NMR》2007,38(3):199-212
A simple labeling approach is presented based on protein expression in [1-13C]- or [2-13C]-glucose containing media that produces molecules enriched at methyl carbon positions or backbone Cα sites, respectively. All of the methyl groups, with the exception of Thr and Ile(δ1) are produced with isolated 13C spins (i.e., no 13C–13C one bond couplings), facilitating studies of dynamics through the use of spin-spin relaxation experiments without artifacts
introduced by evolution due to large homonuclear scalar couplings. Carbon-α sites are labeled without concomitant labeling
at Cβ positions for 17 of the common 20 amino acids and there are no cases for which 13Cα−13CO spin pairs are observed. A large number of probes are thus available for the study of protein dynamics with the results
obtained complimenting those from more traditional backbone 15N studies. The utility of the labeling is established by recording 13C R
1ρ and CPMG-based experiments on a number of different protein systems. 相似文献
69.
《International journal for parasitology》2022,52(7):459-467
A number of examples exist of trade-offs between mating success and survival; that is, success in one fitness component comes at the cost of success in the other fitness component. However, these expected trade-offs are – perhaps even more commonly – not observed. One explanation for this apparent paradox of missing trade-offs could be that the other factors generating fitness variation across individuals confound or obscure the expected trade-off. These confounding effects could arise in two general ways: (i) the additional source of variation could positively (or negatively) influence both fitness components (“shared confounder” hypothesis), or (ii) the additional source of variation could influence only one fitness component (“non-shared confounder” hypothesis). We tested whether parasitism by Gyrodactylus spp. could be a confounder of trade-offs between female preference and susceptibility to predation for male Trinidadian guppies (Poecilia reticulata). As in previous work, we did not find the expected trade-off; that is, the males preferred by females were not more likely to be eaten by predators. Because half of the experimental males were infected by Gyrodactylus in a paired design, we were able to show that females discriminated against infected males, but that infected males were not more susceptible to predation. Our results thus provide support for the non-shared confounder hypothesis. That is, by negatively affecting one fitness component (female choice) but not the other (susceptibility to predation), parasitism by Gyrodactylus could obscure the expected trade-off between female preference and susceptibility to predation. 相似文献
70.
Renton P Speed J Maddaford S Annedi SC Ramnauth J Rakhit S Andrews J 《Bioorganic & medicinal chemistry letters》2011,21(18):5301-5304
A series of 1,5-disubstituted indole derivatives was designed, synthesized and evaluated as inhibitors of human nitric oxide synthase. A variety of flexible and restricted basic amine side chain substitutions was explored at the 1-position of the indole ring, while keeping the amidine group fixed at the 5-position. Compounds having N-(1-(2-(1-methylpyrrolidin-2-yl)ethyl)- (12, (R)-12, (S)-12 and 13) and N-(1-(1-methylazepan-4-yl)- side chains (14, 15, (-)-15 and (+)-15) showed increased inhibitory activity for the human nNOS isoform and selectivity over eNOS and iNOS isoforms. The most potent compound of the series for human nNOS (IC(50)=0.02 μM) (S)-12 showed very good selectivity over the eNOS (eNOS/nNOS=96-fold) and iNOS (iNOS/nNOS=850-fold) isoforms. 相似文献