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91.
Robert Smith Harald T. Johansen Hilde Nilsen Mads H. Haugen Solveig J. Pettersen Gunhild M. Mælandsmo Magnus Abrahamson Rigmor Solberg 《Biochimie》2012
Legumain, an asparaginyl endopeptidase, is up-regulated in tumour and tumour-associated cells, and is linked to the processing of cathepsin B, L, and proMMP-2. Although legumain is mainly localized to the endosomal/lysosomal compartments, legumain has been reported to be localized extracellularly in the tumour microenvironment and associated with extracellular matrix and cell surfaces. The most potent endogenous inhibitor of legumain is cystatin E/M, which is a secreted protein synthesised with an export signal. Therefore, we investigated the cellular interplay between legumain and cystatin E/M. As a cell model, HEK293 cells were transfected with legumain cDNA, cystatin E/M cDNA, or both, and over-expressing monoclonal cell lines were selected (termed M38L, M4C, and M3CL, respectively). Secretion of prolegumain from M38L cells was inhibited by treatment with brefeldin A, whereas bafilomycin A1 enhanced the secretion. Cellular processing of prolegumain to the 46 and 36 kDa enzymatically active forms was reduced by treatment with either substance alone. M38L cells showed increased, but M4C cells decreased, cathepsin L processing suggesting a crucial involvement of legumain activity. Furthermore, we observed internalization of cystatin E/M and subsequently decreased intracellular legumain activity. Also, prolegumain was shown to internalize followed by increased intracellular legumain processing and activation. In addition, in M4C cells incomplete processing of the internalized prolegumain was observed, as well as nuclear localized cystatin E/M. Furthermore, auto-activation of secreted prolegumain was inhibited by cystatin E/M, which for the first time shows a regulatory role of cystatin E/M in controlling both intra- and extracellular legumain activity. 相似文献
92.
Pimthanya Wanichawan Tandekile Lubelwana Hafver Kjetil Hodne Jan Magnus Aronsen Ida Gjervold Lunde Bj?rn Dalhus Marianne Lunde Heidi Kval?y William Edward Louch Theis T?nnessen Ivar Sjaastad Ole Mathias Sejersted Cathrine Rein Carlson 《The Journal of biological chemistry》2014,289(49):33984-33998
Cardiac sodium (Na+)-calcium (Ca2+) exchanger 1 (NCX1) is central to the maintenance of normal Ca2+ homeostasis and contraction. Studies indicate that the Ca2+-activated protease calpain cleaves NCX1. We hypothesized that calpain is an important regulator of NCX1 in response to pressure overload and aimed to identify molecular mechanisms and functional consequences of calpain binding and cleavage of NCX1 in the heart. NCX1 full-length protein and a 75-kDa NCX1 fragment along with calpain were up-regulated in aortic stenosis patients and rats with heart failure. Patients with coronary artery disease and sham-operated rats were used as controls. Calpain co-localized, co-fractionated, and co-immunoprecipitated with NCX1 in rat cardiomyocytes and left ventricle lysate. Immunoprecipitations, pull-down experiments, and extensive use of peptide arrays indicated that calpain domain III anchored to the first Ca2+ binding domain in NCX1, whereas the calpain catalytic region bound to the catenin-like domain in NCX1. The use of bioinformatics, mutational analyses, a substrate competitor peptide, and a specific NCX1-Met369 antibody identified a novel calpain cleavage site at Met369. Engineering NCX1-Met369 into a tobacco etch virus protease cleavage site revealed that specific cleavage at Met369 inhibited NCX1 activity (both forward and reverse mode). Finally, a short peptide fragment containing the NCX1-Met369 cleavage site was modeled into the narrow active cleft of human calpain. Inhibition of NCX1 activity, such as we have observed here following calpain-induced NCX1 cleavage, might be beneficial in pathophysiological conditions where increased NCX1 activity contributes to cardiac dysfunction. 相似文献
93.
In this study the distance, at which polar bears detected and actively responded to approaching snowmobiles was measured and
the behavioural response was recorded. The study was performed on Svalbard, an arctic island where human traffic has increased
substantially in recent years. Fieldwork was conduced in April and/or May during the years 2003–2005. Polar bears were observed
on ice with telescopes and binoculars. Undisturbed polar bears were observed continuously and their behaviours recorded, during
the time when two snowmobiles moved toward the bear(s). Distances between the bear, the observer, and the approaching snowmobiles
were measured using GPS positions taken on the track towards the bear. Data on the behavioural response of 20 encounters with
bears were collected. On average, bears were alerted to the snowmobiles at 1,164 m. Mean distance at which the locomotive
response occurred was 843 m, and there was a statistical significant difference in distance between sex and age classes [326 m
(95% CI = 138–496 m) for adult males; 1,534 m (95% CI = 508–2,768 m) for adult females with cubs; 164 m (95% CI = 49–543 m)
for two adult females without cubs; and 1,160 m (95% CI = 375–1,353 m) for single medium sized bears]. The responses of the
polar bears to the snowmobiles were categorized according to intensity and persistence of reactions. Females with cubs and
single medium sized bears tended to show more intense responses than adult males and lone adult females. Wind direction affects
sound and odour transmission, and although an effect on response distance was not found, the response intensity was affected
by wind direction. We conclude that female polar bears with small cubs in particular may have a greater risk to be disturbed,
since they react at greater distances with amplified reactions; thus, users of snowmobiles should take particular care in
areas where females with cubs are present. 相似文献
94.
Kathrin Bauer Nina Nelius Miriam Reuschenbach Moritz Koch Jürgen Weitz Gunnar Steinert Jürgen Kopitz Philipp Beckhove Mirjam Tariverdian Magnus von Knebel Doeberitz Matthias Kloor 《Cancer immunology, immunotherapy : CII》2013,62(1):27-37
High-level microsatellite-unstable (MSI-H) colorectal carcinomas (CRC) represent a distinct subtype of tumors commonly characterized by dense infiltration with cytotoxic T cells, most likely due to expression of MSI-H-related frameshift peptides (FSP). The contribution of FSP and classical antigens like MUC1 and CEA to the cellular immune response against MSI-H CRC had not been analyzed so far. We analyzed tumor-infiltrating and peripheral T cells from MSI-H (n = 4 and n = 14, respectively) and microsatellite-stable (MSS) tumor patients (n = 26 and n = 17) using interferon gamma ELISpot assays. Responses against 4 FSP antigens and peptides derived from MUC1 to CEA were compared with and without depletion of regulatory T cells, and the results were related to the presence of the respective antigens in tumor tissue. Preexisting FSP-specific T cell responses were detected in all (4 out of 4) tumor-infiltrating and in the majority (10 out of 14) of peripheral T cell samples from MSI-H CRC patients, but rarely observed in MSS CRC patients. Preexisting T cell responses in MSI-H CRC patients were significantly more frequently directed against FSP tested in the present study than against peptides derived from classical antigens MUC1 or CEA (p = 0.049). Depletion of regulatory T cells increased the frequency of effector T cell responses specific for MUC1/CEA-derived peptides and, to a lesser extent, T cell responses specific for FSP. Our data suggest that the analyzed FSP may represent an immunologically relevant pool of antigens capable of eliciting antitumoral effector T cell responses. 相似文献
95.
α1-Microglobulin is a 26 kDa plasma and tissue glycoprotein that belongs to the lipocalin protein superfamily. Recent reports show that it is a reductase and radical scavenger and that it binds heme and has heme-degrading properties. This study has investigated the protective effects of α1-microglobulin against oxidation by heme and reactive oxygen species in the human erythroid cell line, K562. The results show that α1-microglobulin prevents intracellular oxidation and up-regulation of heme oxygenase-1 induced by heme, hydrogen peroxide and Fenton reaction-generated hydroxyl radicals in the culture medium. It also reduces the cytosol of non-oxidized cells. Endogeneous expression of α1-microglobulin was up-regulated by these oxidants and silencing of the α1-microglobulin expression increased the cytosol oxidation. α1-microglobulin also inhibited cell death caused by heme and cleared cells from bound heme. Binding of heme to α1-microglobulin increased the radical reductase activity of the protein as compared to the apo-protein. Finally, α1-microglobulin was localized mainly at the cell surface both when administered exogeneously and in non-treated cells. The results suggest that α1-microglobulin is involved in the defence against oxidative cellular injury caused by haemoglobin and heme and that the protein may employ both heme-scavenging and one-electron reduction of radicals to achieve this. 相似文献
96.
Johan?PahlbergEmail author Magnus?Lindstr?m Petri?Ala-Laurila Nanna?Fyhrquist-Vanni Ari?Koskelainen Kristian?Donner 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2005,191(9):837-844
We report the first study of the relation between the wavelength of maximum absorbance (λmax) and the photoactivation energy (E
a) in invertebrate visual pigments. Two populations of the opossum shrimp Mysis relicta were compared. The two have been separated for 9,000 years and have adapted to different spectral environments (“Sea” and
“Lake”) with porphyropsins peaking at λmax=529 nm and 554 nm, respectively. The estimation of E
a was based on measurement of temperature effects on the spectral sensitivity of the eye. In accordance with theory (Stiles
in Transactions of the optical convention of the worshipful company of spectacle makers. Spectacle Makers’ Co., London, 1948), relative sensitivity to long wavelengths increased with rising temperature. The estimates calculated from this effect are
E
a,529=47.8±1.8 kcal/mol and E
a,554=41.5±0.7 kcal/mol (different at P<0.01). Thus the red-shift of λmax in the “Lake” population, correlating with the long-wavelength dominated light environment, is achieved by changes in the
opsin that decrease the energy gap between the ground state and the first excited state of the chromophore. We propose that
this will carry a cost in terms of increased thermal noise, and that evolutionary adaptation of the visual pigment to the
light environment is directed towards maximizing the signal-to-noise ratio rather than the quantum catch. 相似文献
97.
Otterhag L Gustavsson N Alsterfjord M Pical C Lehrach H Gobom J Sommarin M 《Biochimie》2006,88(1):11-21
The Arabidopsis thaliana protein kinase AtPDK1 was identified as a homologue of the mammalian 3-phosphoinositide-dependent protein kinase-1 (PDK1), which is involved in a number of physiological processes including cell growth and proliferation. We now show that AtPDK1, expressed in E. coli as a recombinant protein, undergoes autophosphorylation at several sites. Using mass spectrometry, three phosphorylated amino acid residues, Ser-177, Ser-276 and Ser-382, were identified, followed by mutational analyses to reveal their roles. These residues are not conserved in mammalian PDK1s. Mutation of Ser-276 in AtPDK1 to alanine resulted in an enzyme with no detectable autophosphorylation. Autophosphorylation was significantly reduced in the Ser177Ala mutant but was only slightly reduced in the Ser382Ala mutant. Other identified sites of importance for autophosphorylation and/or activity of AtPDK1 were Asp-167, Thr-176, and Thr-211. Sites in the mammalian PDK1 corresponding to Asp-167 and Thr-211 are essential for PDK1 autophosphorylation and activity. Autophosphorylation was absent in the Asp167Ala mutant while the Thr176Ala and The211Ala mutants exhibited very low but detectable autophosphorylation, pointing to both similarity and difference between mammalian and plant enzymes. We also demonstrate that AtS6k2, an A. thaliana homologue to the mammalian S6 kinases, is an in vitro target of AtPDK1. Our data clearly show that Asp-167, Thr-176, Ser-177, Thr-211, and Ser-276 in AtPDK1 are important for the downstream phosphorylation of AtS6k2. The results confirm that AtPDK1, like mammalian PDK1, needs phosphorylation at several sites for full downstream phosphorylation activity. Finally, we investigated A. thaliana 14-3-3 proteins as potential AtPDK1 regulatory proteins and the effect of phospholipids on the AtPDK1 activity. Nine of the 12 14-3-3 isoforms tested enhanced AtPDK1 activity whereas one isoform suppressed the activity. No significant effects on AtPDK1 activity by the various phospholipids (including phosphoinositides) were evident. 相似文献
98.
99.
Magnus Schou Carsten Steiger Andrea Varrone Denis Guilloteau Christer Halldin 《Bioorganic & medicinal chemistry letters》2009,19(16):4843-4845
A new dopamine transporter (DAT) ligand, (E)-N-(3-iodoprop-2-enyl)-2β-carbofluoroethoxy-3β-(4′-methyl-phenyl) nortropane (FE-PE2I, 6), derived from PE2I (1), was prepared and found to be a potent inhibitor of rodent DAT in vitro. Compound 6 was radiolabelled with fluorine-18 (t1/2 = 109.8 min) for PET studies in monkeys. In vivo PET measurements showed a regional distribution in brain that corresponds to the known distribution of DAT. This binding was specific, reversible and the kinetics of [18F]6 binding in brain were faster than for its lead compound, [11C]1. The possible presence of a hydroxymethyl-radiometabolite formed by oxidation in the 3β-benzylic position of [18F]6 warrants further detailed evaluation of the metabolism of [18F]6. [18F]6 is a potential radioligand for imaging DATs in the human brain with PET. 相似文献
100.
Magnus Abrahamson Sif Jonsdottir Isleifur Olafsson Olafur Jensson Anders Grubb 《Human genetics》1992,89(4):377-380
Summary Hereditary cystatin C amyloid angiopathy (HCCAA) is a dominantly inherited disease characterized by amyloidosis, dementia and fatal cerebral hemorrhage of young adults. A method for rapid and simple diagnosis of HCCAA is described. It is based upon oligonucleotide-directed enzymatic amplification of a 275-bp genomic DNA segment containing exon 2 of the cystatin C gene from a blood sample, followed by digestion of the amplification product with AluI. Loss of an AluI recognition site in the amplified DNA segment from HCCAA patients results in a deviating band-pattern at agarose gel electrophoresis, compared with that obtained from normal subjects or unaffected HCCAA family members. In a population of 9 patients with manifest HCCAA, 14 patients with other causes of brain hemorrhage and 16 healthy individuals, the diagnostic procedure displayed a sensitivity and specificity for HCCAA of 100%. Amplified DNA segments from 4 HCCAA patients of four different families were analyzed by nucleotide sequencing; the HCCAA-causing mutation in all families was found to be a single TA substitution in the codon for amino acid residue 68 of cystatin C. 相似文献