全文获取类型
收费全文 | 1126篇 |
免费 | 46篇 |
国内免费 | 1篇 |
出版年
2023年 | 8篇 |
2022年 | 21篇 |
2021年 | 32篇 |
2020年 | 22篇 |
2019年 | 23篇 |
2018年 | 20篇 |
2017年 | 20篇 |
2016年 | 27篇 |
2015年 | 68篇 |
2014年 | 50篇 |
2013年 | 78篇 |
2012年 | 122篇 |
2011年 | 104篇 |
2010年 | 45篇 |
2009年 | 59篇 |
2008年 | 76篇 |
2007年 | 71篇 |
2006年 | 54篇 |
2005年 | 55篇 |
2004年 | 65篇 |
2003年 | 46篇 |
2002年 | 42篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 9篇 |
1998年 | 5篇 |
1997年 | 3篇 |
1996年 | 8篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 4篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 2篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有1173条查询结果,搜索用时 46 毫秒
81.
Dimitrios Tsiantoulas Thomas Perkmann Taras Afonyushkin Andreas Mangold Thomas A. Prohaska Nikolina Papac-Milicevic Vincent Millischer Caroline Bartel Sohvi H?rkk? Chantal M. Boulanger Sotirios Tsimikas Michael B. Fischer Joseph L. Witztum Irene M. Lang Christoph J. Binder 《Journal of lipid research》2015,56(2):440-448
Oxidation-specific epitopes (OSEs) present on apoptotic cells and oxidized low density lipoprotein (OxLDL) represent danger-associated molecular patterns that are recognized by different arcs of innate immunity, including natural IgM antibodies. Here, we investigated whether circulating microparticles (MPs), which are small membrane vesicles released by apoptotic or activated cells, are physiological carriers of OSEs. OSEs on circulating MPs isolated from healthy donors and patients with ST-segment elevation myocardial infarction (STE-MI) were characterized by flow cytometry using a panel of OSE-specific monoclonal antibodies. We found that a subset of MPs carry OSEs on their surface, predominantly malondialdehyde (MDA) epitopes. Consistent with this, a majority of IgM antibodies bound on the surface of circulating MPs were found to have specificity for MDA-modified LDL. Moreover, we show that MPs can stimulate THP-1 (human acute monocytic leukemia cell line) and human primary monocytes to produce interleukin 8, which can be inhibited by a monoclonal IgM with specificity for MDA epitopes. Finally, we show that MDA+ MPs are elevated at the culprit lesion site of patients with STE-MI. Our results identify a subset of OSE+ MPs that are bound by OxLDL-specific IgM. These findings demonstrate a novel mechanism by which anti-OxLDL IgM antibodies could mediate protective functions in CVD. 相似文献
82.
Irene Friligou Evangelia Papadimitriou Dimitrios Gatos John Matsoukas Theodore Tselios 《Amino acids》2011,40(5):1431-1440
A fast and efficient microwave-assisted solid phase peptide synthesis (MW-SPPS) of a 51mer peptide, the main heparin-binding
site (60–110) of human pleiotrophin (hPTN), using 2-chlorotrityl chloride resin (CLTR-Cl) following the 9-fluorenylmethyloxycarbonyl/tert-butyl (Fmoc/tBu) methodology and with the standard N,N′-diisopropylcarbodiimide/1-hydroxybenzotriazole (DIC/HOBt) coupling reagents, is described. An MW-SPPS protocol was for the
first time successfully applied to the acid labile CLTR-Cl for the faster synthesis of long peptides (51mer peptide) and with
an enhanced purity in comparison to conventional SPPS protocols. The synthesis of such long peptides is not trivial and it
is generally achieved by recombinant techniques. The desired linear peptide was obtained in only 30 h of total processing
time and in 51% crude yield, in which 60% was the purified product obtained with 99.4% purity. The synthesized peptide was
purified by reversed phase high performance liquid chromatography (RP-HPLC) and identified by electrospray ionization mass
spectrometry (ESI-MS). Then, the regioselective formation of the two disulfide bridges of hPTN 60–110 was successfully achieved
by a two-step procedure, involving an oxidative folding step in dimethylsulfoxide (DMSO) to form the Cys77–Cys109 bond, followed by iodine oxidation to form the Cys67–Cys99 bond. 相似文献
83.
Despite the numerous compost stability and maturity tests, no universally accepted compost stability or maturity index exists. The fluorescein di-acetate (FDA) enzymatic assay, originating from soil studies, is examined here as a potential new compost stability test, and is compared to microbial respiration and phytotoxicity indices. Thirteen composts were used in the study from different source materials. Static microbial respiration activity indices calculated were the cumulative O2 consumptions, O2 consumption rates, total C-CO2 production, the respiratory quotient and the bio C/N ratio. Compost phytotoxicity was quantified via a 7-day tomato seed germination assay. Results showed that the net fluorescein release rates correlated with all stability indices. The germination index marginally correlated with the fluorescein release rates, but not with any of the other stability indices. New limits to classify composts regarding their stability were proposed. 相似文献
84.
Michael MichailidesGerasimos Christou Christos S. AkratosAthanasia G. Tekerlekopoulou Dimitrios V. Vayenas 《International biodeterioration & biodegradation》2011,65(3):560-564
The composting of olive leaves and olive pomace from a three-phase olive mill was tested as a method for solid waste reuse. The process was carried out using a compost windrow and mixing olive leaves and pomace at a ratio of 1:2. Compost was retained in the windrow for 60 days during which thermophilic temperatures developed for the first 40 days. The compost was then placed into a closed area to mature for another 60 days. The final product proved to be high quality amendment with C/N 27.1 and high nutrient concentrations (N, 1.79%; P, 0.17%; K, 4.97%; Na, 2.8%). Mature compost presented the highest germination index (198%) reported to date, as the germination index in the majority of previous studies is under 80%. Furthermore, tests revealed that addition of 31.5 tons of compost per ha, could increase lettuce yield by 145%. 相似文献
85.
Tsikas D Trettin A Zörner AA Gutzki FM 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2011,879(17-18):1476-1484
Pentafluorobenzyl (PFB) bromide (PFB-Br) is a versatile derivatization reagent for numerous classes of compounds. Under electron-capture negative-ion chemical ionization (ECNICI) conditions PFB derivatives of acidic compounds readily and abundantly ionize to produce intense anions due to [M-PFB](-). In the present article we investigated the PFB-Br derivatization of unlabelled acetaminophen (N-acetyl-p-aminophenol, NAPAP-d(0); paracetamol; MW 151) and tetradeuterated acetaminophen (NAPAP-d(4); MW 155) in anhydrous acetonitrile and their GC-ECNICI-MS behavior using methane as the buffer gas. In addition to the expected anions [M-PFB](-) at m/z 150 from NAPAP-d(0) and m/z 154 from NAPAP-d(4), we observed highly reproducibly almost equally intense anions at m/z 149 and m/z 153, respectively. Selected ion monitoring of these ions is suitable for specific and sensitive quantification of acetaminophen in human plasma and urine. Detailed investigations suggest in-source formation of N-acetyl-p-benzoquinone imine (NAPQI; MW 149), the putatively toxic acetaminophen metabolite, from the PFB ether derivative of NAPAP. GC-ECNICI-MS of non-derivatized NAPAP did not produce NAPQI. The peak area ratio of m/z 149 to m/z 150 and of m/z 153 to m/z 154 decreased with increasing ion-source temperature in the range 100-250°C. Most likely, NAPQI formed in the ion-source captures secondary electrons to become negatively charged (i.e., [NAPQI](-)) and thus detectable. Formation of NAPQI was not observed under electron ionization (EI) conditions, i.e., by GC-EI-MS, from derivatized and non-derivatized NAPAP. NAPQI was not detectable in flow injection analysis LC-MS of native NAPAP in positive electrospray ionization (ESI) mode, whereas in negative ESI mode low extent NAPQI formation was observed (<5%). Our results suggest that oxidation of drug derivatives in the ion-sources of mass spectrometers may form intermediates that are produced from activated drugs in enzyme-catalyzed reactions. 相似文献
86.
87.
Panagiotis D Velentzas Athanassios D Velentzas Vassiliki E Mpakou Issidora S Papassideri Dimitrios J Stravopodis Lukas H Margaritis 《Cell biology international》2011,35(1):15-27
Ubiquitin/proteasome‐mediated degradation of eukaryotic proteins is critically implicated in a number of signalling pathways and cellular processes. To specifically impair proteasome activities, in vitro developing Drosophila melanogaster egg chambers were exposed to the MG132 or epoxomicin proteasome inhibitors, while a GAL4/UAS binary genetic system was employed to generate double transgenic flies overexpressing β2 and β6 conditional mutant proteasome subunits in a cell type‐specific manner. MG132 and epoxomicin administration resulted in severe deregulation of in vitro developing egg chambers, which was tightly associated with precocious induction of nurse cell‐specific apoptotic and autophagic death programmes, featured by actin cytoskeleton disorganization, nuclear chromatin condensation, DRICE caspase activation and autophagosome accumulation. In vivo targeted overexpression of β2 and β6 conditional mutants, specifically in the nurse cell compartment, led to a notable up‐regulation of sporadic apoptosis potency during early and mid‐oogenesis ‘checkpoints’, thus reasonably justifying the observed reduction in eclosion efficiency. Furthermore, in response to the intracellular abundance of β2 and β6 conditional mutant forms, specifically in numerous tissues of third instar larval stage, the developmental course was arrested, and lethal phenotypes were obtained at this particular embryonic period, with the double transgenic heterozygote embryos being unable to further proceed to complete maturation to adult flies. Our data demonstrate that physiological proteasome function is required to ensure normal oogenesis and embryogenesis in D. melanogaster, since targeted and cell type‐dependent proteasome inactivation initiates developmentally deregulated apoptotic and autophagic mechanisms. 相似文献
88.
Jean-Marc Jeckelmann Manuel Palacin Dimitrios Fotiadis 《Journal of structural biology》2011,173(2):375-381
The calculation of projection structures (PSs) from Protein Data Bank (PDB)-coordinate files of membrane proteins is not well-established. Reports on such attempts exist but are rare. In addition, the different procedures are barely described and thus difficult if not impossible to reproduce. Here we present a simple, fast and well-documented method for the calculation and visualization of PSs from PDB-coordinate files of membrane proteins: the projection structure visualization (PSV)-method. The PSV-method was successfully validated using the PS of aquaporin-1 (AQP1) from 2D crystals and cryo-transmission electron microscopy, and the PDB-coordinate file of AQP1 determined from 3D crystals and X-ray crystallography. Besides AQP1, which is a relatively rigid protein, we also studied a flexible membrane transport protein, i.e. the l-arginine/agmatine antiporter AdiC. Comparison of PSs calculated from the existing PDB-coordinate files of substrate-free and l-arginine-bound AdiC indicated that conformational changes are detected in projection. Importantly, structural differences were found between the PSV-method calculated PSs of the detergent-solubilized AdiC proteins and the PS from cryo-TEM of membrane-embedded AdiC. These differences are particularly exciting since they may reflect a different conformation of AdiC induced by the lateral pressure in the lipid bilayer. 相似文献
89.
Meury M Harder D Ucurum Z Boggavarapu R Jeckelmann JM Fotiadis D 《Biological chemistry》2011,392(1-2):143-150
High-resolution microscopy techniques provide a plethora of information on biological structures from the cellular level down to the molecular level. In this review, we present the unique capabilities of transmission electron and atomic force microscopy to assess the structure, oligomeric state, function and dynamics of channel and transport proteins in their native environment, the lipid bilayer. Most importantly, membrane proteins can be visualized in the frozen-hydrated state and in buffer solution by cryo-transmission electron and atomic force microscopy, respectively. We also illustrate the potential of the scintillation proximity assay to study substrate binding of detergent-solubilized transporters prior to crystallization and structural characterization. 相似文献
90.
Anna Makri Stamatia Bellou Maria Birkou Konstantinos Papatrehas Dimitrios Bokas Seraphim Papanikolaou George Aggelis 《Engineering in Life Science》2011,11(1):52-58
Tetraselmis sp. and Nannochloropsis oculata, cultivated in industrial‐scale bioreactors, produced 2.33 and 2.44% w/w lipid (calculated as the sum of fatty acid methyl esters) in dry biomass, respectively. These lipids contained higher amounts of neutral lipids and glycolipids plus sphingolipids, than phospholipids. Lipids of Tetraselmis sp. were characterized by the presence of eicosapentaenoic acid (that was located mainly in phospholipids), and octadecatetraenoic acid (that was equally distributed among lipid fractions), while these fatty acids were completely absent in N. oculata lipids. Additionally, lipids produced by 16 newly isolated strains from Greek aquatic environments (cultivated in flask reactors) were studied. The highest percentage of lipids was found in Prorocentrum triestinum (3.69% w/w) while the lowest in Prymnesium parvum (0.47% w/w). Several strains produced lipids rich in eicosapentaenoic and docosahexaenoic acids. For instance, docosahexaenoic acid was found in high percentages in lipids of Amphidinium sp. S1, P. parvum, Prorocentrum minimum and P. triestinum, while lipids produced by Asterionella sp. (?) S2 contained eicosapentaenoic acid in high concentration. These lipids, containing ω‐3‐long‐chain polyunsaturated fatty acids, have important applications in the food and pharmaceutical industries and in aquaculture. 相似文献