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61.
In receptor editing, a phenomenon that has recently come to light and into
favor, a rearranged VDJ or VJ gene segment encoding a variable region of an
Ig chain is replaced by another. In this commentary, the molecular
mechanisms involved in the editing process are examined in some detail.
Editing is most likely mediated by the same V(D)J recombinase activity
responsible for the formation of the original VDJ or VJ segment. An
embedded heptamer, which is present near the 3' end of many VH elements, is
used as the recombination signal sequence at the Ig heavy chain locus. It
has been postulated that the mediation of receptor editing is the
evolutionary force maintaining the embedded heptamer. Some of the evidence
for and against this hypothesis is discussed.
相似文献
62.
Expression of lysosomal acid lipase mutants detected in three patients with cholesteryl ester storage disease 总被引:1,自引:0,他引:1
Pagani F; Garcia R; Pariyarath R; Stuani C; Gridelli B; Paone G; Baralle FE 《Human molecular genetics》1996,5(10):1611-1617
Lysosomal acid lipase (LAL) gene mutations were identified in three
patients with cholesteryl ester storage disease (CESD). Direct sequencing
of genomic DNA revealed that: patient 1 was a compound heterozygote for a
P181L mutation and an A to G3' splice site substitution that causes
skipping of exon 7, with a loss of 49 amino acids from LAL (delta 205-253);
patient 2 was a compound heterozygote for a G66V mutation and a 5' splice
site mutation (G to A) that leads to skipping of exon 8 (delta 254-277);
and patient 3 was a compound heterozygote for a L273S mutation and an
unidentified null allele. Furthermore, patients 2 and 3 showed a novel G-2A
polymorphism that could be detected by an Xbal restriction fragment length
polymorphism. All these mutants and a previously reported H274Y allele were
expressed in vitro in HeLa cells using the vaccinia T7 expression system.
The resulting recombinant proteins were inactive towards cholesteryl oleate
and trioleylglycerol, demonstrating the direct involvement of these
mutations in the pathogenesis of CESD. Immunoblotting of normal LAL
expressed in HeLa cells revealed four major molecular forms, at least two
of high molecular mass (54 and 50-51 kDa) and two of low molecular mass (42
and 43 kDa). L273S and P181L substitutions and delta 254-277 were shown to
result in altered LAL molecular forms, some of which suggest that
post-translational processing may interfere with the catalytic activity of
LAL.
相似文献
63.
Rodger FE; Young FM; Fraser HM; Illingworth PJ 《Human reproduction (Oxford, England)》1997,12(8):1723-1729
The corpus luteum is essential for the maintenance of early pregnancy in
women. Angiogenesis may be one factor involved in luteal rescue. The aim of
this study was to determine the changes in endothelial cell proliferation
throughout the luteal phase and in human chorionic gonadotrophin
(HCG)-simulated early pregnancy. Human corpora lutea obtained throughout
the luteal phase and in simulated early pregnancy were immunostained with
antibodies for endothelial and proliferating cells. Number and distribution
of endothelial and proliferating cells were examined. Endothelial cells
were least abundant in the early luteal phase, increasing in the mid-luteal
phase (P < 0.03). Endothelial numbers did not differ significantly
between the late and the rescued corpora lutea. Endothelial cell
proliferation was greatest in the early luteal phase and continued at a
lower level during later stages. Simulated early pregnancy resulted in no
change in endothelial cell proliferation. These results showed that a high
degree of endothelial cell proliferation is associated with formation of
the human corpus luteum. Unchanging levels of proliferation following HCG
treatment (for 5-8 days from day 12 to day 16 post-ovulation, at 125 IU to
16,000 IU, following a daily doubling of dose) suggest that alternative
processes are involved during luteal rescue.
相似文献
64.
JF Correia‐Silva O Bruna‐Romero RG Resende LPM Miranda FE Oliveira FO Costa SG Xavier SP Figueiredo‐Neves HC Almeida H Bittencourt RS Gomez 《Oral diseases》2010,16(2):210-216
Oral Diseases (2010) 16 , 210–216 Objective: The purpose of this study was to investigate the use of saliva for the identification of human cytomegalovirus (HCMV) in allogeneic hematopoietic stem cell transplant patients by real time PCR compared with blood. Materials and methods: Saliva and blood samples were sampled weekly in 30 allogeneic hematopoietic stem cell transplant patients until 100 days after transplant. Total genomic DNA, extracted from saliva and whole‐blood samples, was used for HCMV real time PCR. Nonparametric tests were performed, and P value ≤0.05 was considered statistically significant. Results: Human cytomegalovirus DNA load in saliva showed a high correlation with viral DNA in the blood ( R = 0.858; P < 0.0001). Blood DNA levels also correlated with HCMV antigenemia ( R = 0.773; P < 0.0001). The HCMV levels in saliva ( P = 0.015) and blood ( P = 0.008) showed higher levels at the beginning of antiviral treatment, with clear reduction after this period. Saliva showed earlier HCMV reactivation than blood detected by real time PCR and antigenemia assay in 11 out of 22 subjects. Conclusions: This study shows that the real time PCR test could be useful to identify HCMV DNA in saliva and to monitor patients at risk of cytomegalovirus disease after allogeneic hematopoietic stem cell transplant. However, further studies are necessary to confirm this data. 相似文献
65.
AO Fawole A Shah AO Fabanwo O Adegbola AA Adewunmi AB Eniayewun K Dara AM El-Ladan AC Umezulike FE Alu AA Adebayo FO Obaitan OE Onala Y Usman AO Sullayman S Kailani M Sa'id 《African health sciences》2012,12(1):32-40
Background
Maternal mortality in poor countries reflects the under-development in these societies. Global recognition of the burden of maternal mortality and the urgency for a reversal of the trend underpin the Millenium Development Goals (MDGs).Objective
To determine risk factors for maternal mortality in institutional births in Nigeria.Method
Twenty one health facilities in three states were selected using stratified multi-stage cluster sampling strategy. Information on all delivered mothers and their newborn infants within a three-month period was culled from medical records.Results
A total of 9 208 deliveries were recorded. About one-fifth (20.5%) of women had no antenatal care while 79.5% had at least one antenatal visit during pregnancy. Four-fifths (80.5%) of all deliveries were normal deliveries. Elective and emergency caesarean section rates were 3.1% and 11.5% respectively. There were 79 maternal deaths and 8 526 live births, giving a maternal mortality ratio of 927 maternal deaths per 100 000 live births. No antenatal care, parity, level of education, and mode of delivery were significantly associated with maternal mortality. Low maternal education, high parity, emergency caesarean delivery, and high risk patients risk independently predicted maternal mortality.Conclusion
Meeting goal five of the MDGs remains a major challenge in Nigeria. Multi-sectoral approaches and focused political will are needed to revert the high maternal mortality. 相似文献66.
Investigation of the relative infectivity and pathogenicity of different hepatitis C virus genotypes in hemophiliacs 总被引:1,自引:0,他引:1
Jarvis LM; Ludlam CA; Ellender JA; Nemes L; Field SP; Song E; Chuansumrit A; Preston FE; Simmonds P 《Blood》1996,87(7):3007-3011
To assess the relative infectivity and pathogenicity of variants of hepatitis C virus (HCV) genotypes, the distribution of genotypes in hemophilic patients who had been treated with nonvirally inactivated factor concentrates or cryoprecipitates prepared from local blood donors was compared with those found in the respective blood donor populations. Genotype frequencies differed markedly in the four countries investigated (Scotland, Hungary, South Africa, and Thailand) but in each, the HCV genotype distributions in hemophiliacs and blood donors were similar. In addition, HCV genotypes in recipients of commercially manufactured concentrates were similar to those found in the US general population. These findings provide no evidence that HCV genotypes differ significantly from each other in replication rate, transmissibility, or infectivity. 相似文献
67.
Antibiotic resistance presents a daunting challenge to health professionals worldwide and has the potential to create major problems for modern health care, resulting in more medical expenditure, extended hospital stays and increased morbidity and mortality. Advanced genome sequencing technologies present a complex picture of resistance, extending our understanding beyond the pharmacotherapeutic interface between pathogens and antibiotics. This review discusses the global scope and scale of antibiotic resistance and contextualizes it for the dental practitioner, emphasizing the role we must play in limiting the progression of resistance through antibiotic stewardship and disease prevention. 相似文献
68.
69.
Casselman JW; Offeciers FE; Govaerts PJ; Kuhweide R; Geldof H; Somers T; D'Hont G 《Radiology》1997,202(3):773
70.
The molecular basis of type I or III Protein S deficiency has been investigated in three kindred also showing independent inheritance of factor V (FV) Leiden. A T to C transition in codon 570 (Met-->Thr) was identified in the propositi and shown to segregate with protein S deficiency in all but one of the affected members of two kindred. This individual was heterozygous for a second transition (C to T) causing substitution of serine 624 by leucine. A second member of the same family, with markedly reduced free protein S levels when compared with affected relatives, was heterozygous for both mutations. Haplotype analysis of individuals with the mutated ATG570ACG allele in the two kindred suggested they may have been related by a common ancestor. A G to A transition resulting in substitution of cysteine 145 by tyrosine was detected in the third kindred. All mutations are believed to interfere with protein S binding to C4b-binding protein resulting in reduced free protein S levels. Of the five individuals studied who had experienced thrombotic events, three had combined protein S deficiency and FV Leiden reemphasising the importance of FV Leiden as an additional risk factor for thrombosis in protein S deficiency. 相似文献