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81.
Silvia Vavrova Danka Valkova Hana Drahovska Juraj Kokavec Jozef Mravec Jan Turna 《Biometals》2006,19(5):453-460
We have found and sequenced a significant part of the previously described tellurite resistance determinant on mini-Mu derivative
pPR46, named pNT3B, originally cloned from a large conjugative plasmid pTE53, found in Escherichia coli. This plasmid contains genes essential for tellurite resistance, together with the protective region bearing genes terX, Y, W, and the conserved spacing region bearing several ORFs of unknown function. Computer analysis of obtained sequence revealed
a close similarity to the formerly described ter operons found on the Serratia marcescens plasmid R478 and the chromosome of Escherichia coli O157:H7. This finding confirms the presence of a whole region on the large conjugative plasmid that pTE53 originated from
a uropathogenic E. coli strain, and suggests its possible role in horizontal gene transfer, resulting in the development of new pathogenic E. coli strains. 相似文献
82.
Saumitri Bhattacharyya Jeremy Keirsey Beatriz Russell Juraj Kavecansky Kate Lillard-Wetherell Kambiz Tahmaseb John J. Turchi Joanna Groden 《The Journal of biological chemistry》2009,284(22):14966-14977
The BLM helicase associates with the telomere structural proteins TRF1 and
TRF2 in immortalized cells using the alternative
lengthening of telomere (ALT) pathways. This work
focuses on identifying protein partners of BLM in cells using ALT. Mass
spectrometry and immunoprecipitation techniques have identified three proteins
that bind directly to BLM and TRF2 in ALT cells: telomerase-associated protein
1 (TEP1), heat shock protein 90 (HSP90), and topoisomerase IIα
(TOPOIIα). BLM predominantly co-localizes with these proteins in foci
actively synthesizing DNA during late S and G2/M phases of the cell
cycle when ALT is thought to occur. Immunoprecipitation studies also indicate
that only HSP90 and TOPOIIα are components of a specific complex
containing BLM, TRF1, and TRF2 but that this complex does not include TEP1.
TEP1, TOPOIIα, and HSP90 interact directly with BLM in vitro
and modulate its helicase activity on telomere-like DNA substrates but not on
non-telomeric substrates. Initial studies suggest that knockdown of
BLM in ALT cells reduces average telomere length but does not do so
in cells using telomerase.Bloom syndrome
(BS)4 is a genetic
disease caused by mutation of both copies of the human BLM gene. It
is characterized by sun sensitivity, small stature, immunodeficiency, male
infertility, and an increased susceptibility to cancer of all sites and types.
The high incidence of spontaneous chromosome breakage and other unique
chromosomal anomalies in cells from BS patients indicate an increase in
homologous recombination in somatic cells
(1). Another notable feature of
non-immortalized and immortalized cells from BS individuals is the presence of
telomeric associations (TAs) between homologous chromosomes
(2). Work from our group and
others have suggested a role for BLM in recombination-mediated mechanisms of
telomere elongation or ALT (alternative lengthening of telomeres), processes
that maintain/elongate telomeres in the absence of telomerase
(3–5).
However, the exact mechanism by which BLM contributes to telomere stability is
unknown.Several proteins interact with and regulate BLM helicase activity,
including two telomere-specific proteins, TRF1 and TRF2
(6,
7). Although TRF2 stimulates
BLM unwinding of telomeric and non-telomeric 3′-overhang substrates,
TRF1 inhibits BLM unwinding of telomeric substrates. TRF2-mediated stimulation
of BLM helicase activity on a telomeric substrate is observed when TRF2 is
present in excess or with equimolar amount of TRF1 but not when TRF1 is
present in molar excess. Both proteins associate with BLM specifically in ALT
cells in vivo, suggesting their involvement in the ALT pathways. In
addition to TRF1 and TRF2, the telomere single-strand DNA-binding protein POT1
strongly stimulates BLM helicase activity on long telomeric forked duplexes
and D-loop structures (8).
Other proteins also play an important role in telomere maintenance in
telomerase-negative cells, including RAD50, NBS1, and MRE11, which co-localize
with TRF1 and TRF2 in specialized ALT-associated promyelocytic leukemia (PML)
nuclear bodies (APBs)
(9–11).
Thus, we hypothesize that BLM complex formation may be essential for the ALT
mechanism, and its modification may occur dynamically during the specific
nucleic acid transactions required to protect the telomere in cells using the
ALT pathways.This study has identified previously unknown protein partners of BLM and
TRF2 in ALT cells using double immunoprecipitation and mass spectrometry (MS).
These include telomerase-associated protein 1 (TEP1), heat shock protein 90
(HSP90), and topoisomerase IIα (TOPOIIα). These proteins associate
with BLM and TRF2 in cells using ALT but not in cells using telomerase and
directly interact with BLM in vitro. This complex of proteins
localizes to sites of new DNA synthesis in vivo in ALT cells,
suggesting a role in telomere maintenance. We also identified HSP90 and
TOPOIIα in another ALT-specific complex consisting of BLM, TRF1, and
TRF2 but not TEP1. In vitro analyses demonstrate that HSP90 inhibits
BLM helicase activity using both telomeric and non-telomeric substrates,
whereas TEP1 and TOPOIIα initially slow the kinetics of BLM unwinding
only using telomeric substrates. These findings suggest the presence of
dynamic BLM-associated ALT complexes that include previously unidentified
interacting proteins. The function of TEP1 in the BLM·TRF2 complex
remains unclear, although its previously described interaction with the RNA
subunit of telomerase (12)
suggests an interesting hypothesis of cross-talk between mechanisms of
telomere elongation. 相似文献
83.
Twan van den Beucken Marianne Koritzinsky Hanneke Niessen Ludwig Dubois Kim Savelkouls Hilda Mujcic Barry Jutten Juraj Kopacek Sylvia Pastorekova Albert J. van der Kogel Philippe Lambin Willem Voncken Kasper M. A. Rouschop Bradly G. Wouters 《The Journal of biological chemistry》2009,284(36):24204-24212
84.
Marinović M Cicvarić T Juretić I Grzalja N Medved I Ahel J 《Collegium antropologicum》2010,34(Z2):243-245
Because of a possible delayed wound healing, critical colonization and infection of wounds present a problem for surgeons. Colonized and infected wounds are a potential source for cross-infection. Molndal technique of wound dressing has proven to be effective in prevention of infection. Also the wound heal better and faster. In our study we wanted to describe the benefits of the Molndal technique wound dressing after laparoscopic cholecistectomy compared to traditional wound dressing technique. Molndal technique consisted of wound dressing with Aquacel Ag--Hydrofiber (ConvaTec, Dublin, Ireland). Traditional technique was performed using gauze compresses and hypoallergic adhesives. We analyzed the results of 100 patients after laparoscopic cholecystectomy. 50 patients were treated by Molndal technique and 50 patients by the traditional technique of wound dressing. In the group treated by Molndal technique only 1 (2%) patient has revealed a wound infection, proven by positive microbiological examination and suppuration, mostly in the subumbilical incision. In the traditional technique group 7 (14%) patients developed wound infection also predominantly in the subumbilical incision. The difference was statistically significant (p < 0.01). Our results are clearly showing that Molndal technique is effective in preventing the infection of subumbilical incision wound and is to by recommend for regular use at designated site after laparoscopic cholecistectomy. 相似文献
85.
86.
Matej Vesteg Rostislav Vacula Jürgen M. Steiner Bianka Mateá?iková Wolfgang L?ffelhardt Broňa Brejová Juraj Kraj?ovi? 《DNA research》2010,17(4):223-231
The chloroplasts of Euglena gracilis bounded by three membranes arose via secondary endosymbiosis of a green alga in a heterotrophic euglenozoan host. Many genes were transferred from symbiont to the host nucleus. A subset of Euglena nuclear genes of predominately symbiont, but also host, or other origin have obtained complex presequences required for chloroplast targeting. This study has revealed the presence of short introns (41–93 bp) either in the second half of presequence-encoding regions or shortly downstream of them in nine nucleus-encoded E. gracilis genes for chloroplast proteins (Eno29, GapA, PetA, PetF, PetJ, PsaF, PsbM, PsbO, and PsbW). In addition, the E. gracilis Pbgd gene contains two introns in the second half of presequence-encoding region and one at the border of presequence-mature peptide-encoding region. Ten of 12 introns present within presequence-encoding regions or shortly downstream of them identified in this study have typical eukaryotic GT/AG borders, are T-rich, 45–50 bp long, and pairwise sequence identities range from 27 to 61%. Thus single recombination events might have been mediated via these cis-spliced introns. A double crossing over between these cis-spliced introns and trans-spliced introns present in 5′-UTRs of Euglena nuclear genes is also likely to have occurred. Thus introns and exon-shuffling could have had an important role in the acquisition of chloroplast targeting signals in E. gracilis. The results are consistent with a late origin of photosynthetic euglenids. 相似文献
87.
Juraj Balkovič Jozef Kollár Gabriela Čemanová Vojtech Šimonovič 《Folia Geobotanica》2010,45(3):253-277
A fine-scaled approach for predicting soil acidity using plant species in a spatially limited area (?epú?ky Nature Reserve, Slovakia) is presented here. This approach copes with some specific limitations: i) a limited pool of vegetation data may make the predictions too sensitive to the lack of species information, and ii) the predictions may be sensitive to the narrow pH gradient. Vegetation relevés and soil reaction (pH-H2O and pH-CaCl2) were systematically recorded. A set of species indicator values and amplitudes was calibrated with physical pH data using the Weighted Averaging (WA), HOF modelling and Non-Metric Multidimensional Scaling (NMDS) methods, along with Ellenberg indicator values. Two prediction methods were tested: i) WA and ii) Amplitude Overlap (AO). WA prediction with Ellenberg’s and WA-calibrated species indicator values were the most powerful technique (R 2?=?68.4–68.7% and 53.4–59.1% for pH-CaCl2 and pH-H2O, respectively). WA-prediction with HOF-based indicator values was less effective (R 2?=?61.7% and 50.7%) due to the decrease in species’ information because with HOF modelling many species are assumed indifferent or too rare. The NMDS method does not bring any significant gain to the calibration, though it avoids the lack of species information. The AO method was proven to be less powerful under studied circumstances, because it is sensitive both to the lack of species’ information and to the truncation of species responses. The results prove that a spatially explicit approach can provide significant indices to estimate changes in soil acidity – pH-CaCl2 better than pH-H2O. 相似文献
88.
Physiological evidence for the involvement of peptide YY in the regulation of energy homeostasis in humans 总被引:1,自引:0,他引:1
Guo Y Ma L Enriori PJ Koska J Franks PW Brookshire T Cowley MA Salbe AD Delparigi A Tataranni PA 《Obesity (Silver Spring, Md.)》2006,14(9):1562-1570
Objective: To explore the potential role of the endogenous peptide YY (PYY) in the long‐term regulation of body weight and energy homeostasis. Research Methods and Procedures: Fasting and postprandial plasma PYY concentrations were measured after an overnight fast and 30 to 180 minutes after a standardized meal in 29 (21 men/8 women) non‐diabetic subjects, 16 of whom had a follow‐up visit 10.8 ± 1.4 months later. Ratings of hunger and satiety were collected using visual analog scales. Resting metabolic rate (RMR) (15‐hour RMR) and respiratory quotient (RQ) were assessed using a respiratory chamber. Results: Fasting PYY concentrations were negatively correlated with various markers of adiposity and negatively associated with 15‐hour RMR (r = ?0.46, p = 0.01). Postprandial changes in PYY (area under the curve) were positively associated with postprandial changes in ratings of satiety (r = 0.47, p = 0.01). The maximal PYY concentrations achieved after the meal (peak PYY) were negatively associated with 24‐hour RQ (r = ?0.41, p = 0.03). Prospectively, the peak PYY concentrations were negatively associated with changes in body weight (r = ?0.58, p = 0.01). Discussion: Our data indicate that the endogenous PYY may be involved in the long‐term regulation of body weight. It seems that this long‐term effect was not exclusively driven by the modulation of food intake but also by the control of energy expenditure and lipid metabolism. 相似文献
89.
90.