全文获取类型
收费全文 | 460篇 |
免费 | 22篇 |
国内免费 | 8篇 |
专业分类
490篇 |
出版年
2022年 | 3篇 |
2021年 | 9篇 |
2020年 | 5篇 |
2019年 | 7篇 |
2018年 | 16篇 |
2017年 | 10篇 |
2016年 | 16篇 |
2015年 | 21篇 |
2014年 | 12篇 |
2013年 | 19篇 |
2012年 | 24篇 |
2011年 | 24篇 |
2010年 | 15篇 |
2009年 | 7篇 |
2008年 | 14篇 |
2007年 | 15篇 |
2006年 | 17篇 |
2005年 | 10篇 |
2004年 | 28篇 |
2003年 | 11篇 |
2002年 | 19篇 |
2001年 | 17篇 |
2000年 | 7篇 |
1999年 | 9篇 |
1996年 | 6篇 |
1995年 | 3篇 |
1993年 | 3篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1988年 | 11篇 |
1987年 | 9篇 |
1986年 | 4篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1980年 | 4篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1973年 | 7篇 |
1972年 | 4篇 |
1971年 | 6篇 |
1970年 | 8篇 |
1969年 | 7篇 |
1967年 | 7篇 |
1966年 | 7篇 |
1889年 | 3篇 |
1887年 | 4篇 |
1886年 | 3篇 |
排序方式: 共有490条查询结果,搜索用时 15 毫秒
1.
Anna Adamska‐Bartłomiejczyk Attila Borics Csaba Tömböly Szabolcs Dvorácskó Marek Lisowski Alicja Kluczyk Grzegorz Wołczański Justyna Piekielna‐Ciesielska Anna Janecka 《Journal of peptide science》2017,23(12):864-870
Three novel morphiceptin analogs, in which Pro in position 2 and/or 4 was replaced by cis‐4‐aminoproline connected with the preceding amino acid through the primary amino group, were synthesized. The opioid receptor affinities, functional assay results, enzymatic degradation studies and experimental and in silico structural analysis of such analogs are presented. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd. 相似文献
2.
Aerobiological monitoring enables the definition of seasonal fungal spore concentrations and also intradiurnal time when the
highest concentrations of spores could cause or increase allergy symptoms. These data are useful to estimate symptoms of disease,
duration of infection and how advanced the illness is in people suffering from fungal allergens. The aim of the study was
to compare the concentrations of fungal spores (Alternaria, Botrytis, Cladosporium, Didymella, Ganoderma) during dry and rainy periods and to analyse their intradiurnal changes. Average daily spore concentrations in dry and rainy
periods were compared, using z test, separately for each taxon, season and for a combined 3-year period. Intradiurnal periodicity of fungal spore concentrations
was analysed on the basis of three complementary diagrams. These spore concentrations were presented using three curves for
all, dry and rainy days in 1997–1999 (April–November). The spore percentage in particular hours was normalized in relation
to the daily spore sum accepted as 100%. Two further diagrams enabled the more precise analysis of the highest concentrations
in dry days. Daily Botrytis and Cladosporium spore concentrations did not show significant differences between dry and rainy periods. In the case of Didymella and Ganoderma spore concentrations, there were no significant differences between both weather types in the single years, although there
was a significant difference when a 3-year period was considered. The differences between daily concentrations of Alternaria spores in dry and rainy periods occurred in 1997 and in a 3-year period. Intradiurnal periodicity of spore concentrations
was different for ‘dry’ and ‘wet’ fungal spores. Dry spores are released from the spore-producing parts of the fungus under
conditions of decreasing humidity and increasing airflow. Examples of dry spores are those from Alternaria, Cladosporium and Botrytis. Wet spores, such as those from many Ascomycetes (Didymella) and Basidiomycetes (Ganoderma), are released into the atmosphere by processes related to humidity conditions or rain. The highest concentrations of ‘dry’
spores were observed early in the afternoon, while highest values of ‘wet’ spore concentrations occurred in the predawn hours.
Statistically non-significant differences between daily spore concentrations in dry and rainy periods of single seasons were
found except for Alternaria. Statistically significant differences could occur when the studied period was longer than one season (Alternaria, Didymella, Ganoderma). The highest concentrations of Alternaria, Botrytis and Cladosporium spores were recorded at noon and early in the afternoon. Concentrations of Didymella and Ganoderma spores were highest in the predawn hours. 相似文献
3.
4.
Łukasz Mokros Michał Seweryn Karbownik Katarzyna Nowakowska-Domagała Janusz Szemraj Łukasz Wieteska Karol Woźniak 《Biological Rhythm Research》2016,47(6):865-871
Background: There is barely any evidence of antipsychotic drugs affecting the molecular clockwork in human, yet it is suggested that clock genes are associated with dopaminergic transmission, i.e. the main target of this therapeutics. We decided to verify if haloperidol and olanzapine affect expression of CLOCK, BMAL1, PER1 and CRY1 in a human central nervous system cell line model. Methods: U-87MG human glioblastoma cell line was used as an experimental model. The cells were incubated with or without haloperidol and olanzapine in the concentration of 5 and 20 μM for 24 h. Real-time quantitative polymerase chain reaction with the ΔCT analysis was used to examine the effect of haloperidol and olanzapine on the mRNA expression of the genes. Results: At 5 μM, haloperidol decreased expression of CRY1 almost 20-fold. There was nearly a 1.5-fold increase in expression of PER1. Considering the 20 μM haloperidol concentration and both olanzapine concentrations, no other statistically significant effect was observed. Conclusions: At certain concentration, haloperidol seems to affect expression of particular clock genes in a human central nervous system cell line model, yet mechanism underlying this phenomenon remains elusive. 相似文献
5.
Dan‐yan Zhu Jia‐ying Wu Huan Li Jie‐ping Yan Mei‐yuan Guo Yan‐bo Wo Yi‐jia Lou 《Journal of cellular biochemistry》2010,109(3):498-508
Relatively little is known about mitochondria metabolism in differentiating embryonic stem (ES) cells. Present research focused on several elements of cellular energy metabolism in hepatic‐like tissue derived from mouse ES cells. We demonstrated that mitochondrial location patterns and mitochondrial membrane potential (ΔΨm) existed in subsequent differentiation of the tissue. Mitochondriogenesis appeared at the early stage and kept a normal ΔΨm in differentiated mature hepatocytes. Peroxisome proliferator‐activated receptor‐α (PPAR‐α) expression was transitorily increased at the beginning, and kept a relatively low level later, which accompanied by expression of PPAR‐γ coactivator (PGC)‐1α, a master regulator of mitochondrial biogenesis. PPAR‐β expression showed robust up‐regulation in the late differentiation course. Enhanced co‐expressions of PPAR‐β and albumin with catalysis of UDP‐glucuronosyltransferases (UGTs) were observed at mature stage. While PPAR‐γ expression changed little before and after differentiation. Mitochondriogenesis could be accelerated by PPAR‐α specific agonist WY14643 and abolished by its antagonist GW6471 at the early stage. Neither of them affected mitochondrial ΔΨm and albumin generation in the differentiated hepatocytes. Furthermore, maturation of hepatic‐like tissue and mitochondriogenesis in hepatocyte could be efficiently stimulated by PPAR‐β specific agonist L165041 and abolished by PPAR‐β specific antagonist GSK0660, but not affected by PPAR‐γ specific agonist GW1929. In conclusion, the derived hepatic tissue morphologically possessed cellular energy metabolism features. PPAR‐α seemed only necessary for early mitochondriogenesis, while less important for ΔΨm retention in the mature tissue derived. The stimulation of PPAR‐β but not ‐γ enhanced hepatogenesis, hepatocytes maturation, and mitochondriogenesis. PPAR‐β took an important role in cellular energy metabolism of hepatogenesis. J. Cell. Biochem. 109: 498–508, 2010. © 2009 Wiley‐Liss, Inc. 相似文献
6.
Y Y Wo A L McCormack J Shabanowitz D F Hunt J P Davis G L Mitchell R L Van Etten 《The Journal of biological chemistry》1992,267(15):10856-10865
Low molecular weight phosphotyrosyl protein phosphatases of human placenta and human red cell were purified and sequenced by a combination of Edman degradation and tandem mass spectrometry. Screening of a human placental lambda gt11 cDNA library yielded overlapping cDNA clones coding for two distinct human cytoplasmic low molecular weight phosphotyrosyl protein phosphatases (HCPTPs). The two longest clones, designated HCPTP1-1 and HCPTP2-1, were found to have identical nucleotide sequences, with the exception of a 108-base pair segment in the middle of the open reading frame. Polymerase chain reaction studies with human genomic DNA suggest that the difference between HCPTP1-1 and HCPTP2-1 does not result from alternative RNA splicing. Studies with a human chromosome 2-specific library confirmed that these sequences are located on chromosome 2, which is known to be the location of red cell acid phosphatase locus ACP1. The coding sequences of HCPTP1-1 and HCPTP2-1 were placed downstream from a bacteriophage T7 promoter and the proteins were expressed in Escherichia coli. The resulting recombinant enzymes (designated HCPTP-A and HCPTP-B, respectively) showed molecular weights of 18,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and both of them exhibited immunoreactivity with antisera raised against authentic human placental and bovine heart enzymes. The expressed proteins were highly active towards the phosphatase substrates p-nitrophenyl phosphate, beta-naphthyl phosphate, and O-phospho-L-tyrosine, but not alpha-naphthyl phosphate, threonine phosphate, or O-phospho-L-serine. HCPTP-A and -B possessed effectively identical amino acid compositions, immunoreactivities, inhibition by formaldehyde, and kinetic properties when compared with two human red cell acid phosphatase isoenzymes. It is concluded that HCPTP-A and -B are the fast and slow forms of red cell acid phosphatase, respectively, and that this enzyme is not unique to the red cell but is instead expressed in all human tissues. 相似文献
7.
8.
Wu CW Chien MS Liu TY Lin GJ Lee WC Huang C 《Applied microbiology and biotechnology》2011,92(4):815-821
Classical swine fever virus (CSFV) Erns is an envelope glycoprotein possessing RNase activity. The Erns-based enzyme-linked immunosorbent assay (ELISA) has been considered a discriminating diagnostic test for differentiating
infected from vaccinated animals. The purpose of this study was to produce a specific monoclonal antibody (MAb) to Erns for further developing an indirect sandwich ELISA. The MAb CW813 was shown to specifically recognize both the monomer and
dimer forms of Pichia pastoris yeast-expressed Erns (yErns). The antigenic site recognized by MAb CW813 was mapped to the region of amino acid residues 101–160 of Erns where it was neither a neutralizing epitope nor essential to RNase activity. Furthermore, MAb CW813 was utilized as a capture
antibody to develop a yErns-based indirect sandwich ELISA for detecting swine antibody to Erns. The assay demonstrated a high sensitivity and specificity that may provide an alternative method for developing a diagnostic
kit with easy manipulation and low cost. 相似文献
9.
Nervous necrosis virus replicates following the embryo development and dual infection with iridovirus at juvenile stage in grouper 总被引:1,自引:0,他引:1
Kuo HC Wang TY Hsu HH Chen PP Lee SH Chen YM Tsai TJ Wang CK Ku HT Lee GB Chen TY 《PloS one》2012,7(4):e36183
Infection of virus (such as nodavirus and iridovirus) and bacteria (such as Vibrio anguillarum) in farmed grouper has been widely reported and caused large economic losses to Taiwanese fish aquaculture industry since 1979. The multiplex assay was used to detect dual viral infection and showed that only nervous necrosis virus (NNV) can be detected till the end of experiments (100% mortality) once it appeared. In addition, iridovirus can be detected in a certain period of rearing. The results of real-time PCR and in situ PCR indicated that NNV, in fact, was not on the surface of the eggs but present in the embryo, which can continue to replicate during the embryo development. The virus may be vertically transmitted by packing into eggs during egg development (formation) or delivering into eggs by sperm during fertilization. The ozone treatment of eggs may fail to remove the virus, so a new strategy to prevent NNV is needed. 相似文献
10.
Structural models have been produced for three types of non-NMDA inotropic glutamate receptors: an AMPA receptor, GluR1, a kainate receptor, GluR6; and a low-molecular-weight kainate receptor from goldfish, GFKAR alpha. Modeling was restricted to the domains of the proteins that bind the neurotransmitter glutamate and that form the ion channel. Model building combined homology modeling, distance geometry, molecular mechanics, interactive modeling, and known constraints. The models indicate new potential interactions in the extracellular domain between protein and agonists, and suggest that the transition from the "closed" to the "open" state involves the movement of a conserved positive residue away from, and two conserved negative residues into, the extracellular entrance to the pore upon binding. As a first approximation, the ion channel domain was modeled with a structure comprising a central antiparallel beta-barrel that partially crosses the membrane, and against which alpha-helices from each subunit are packed; a third alpha-helix packs against these two helices in each subunit. Much, but not all, of the available data were consistent with this structure. Modifying the beta-barrel to a loop-like topology produced a model consistent with available data. 相似文献