全文获取类型
收费全文 | 553篇 |
免费 | 25篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 55篇 |
妇产科学 | 3篇 |
基础医学 | 65篇 |
口腔科学 | 12篇 |
临床医学 | 76篇 |
内科学 | 139篇 |
皮肤病学 | 21篇 |
神经病学 | 2篇 |
特种医学 | 139篇 |
外科学 | 16篇 |
综合类 | 10篇 |
预防医学 | 7篇 |
眼科学 | 4篇 |
药学 | 13篇 |
肿瘤学 | 16篇 |
出版年
2022年 | 2篇 |
2021年 | 6篇 |
2019年 | 1篇 |
2018年 | 6篇 |
2017年 | 1篇 |
2016年 | 5篇 |
2015年 | 9篇 |
2014年 | 9篇 |
2013年 | 14篇 |
2012年 | 8篇 |
2011年 | 10篇 |
2010年 | 24篇 |
2009年 | 20篇 |
2008年 | 8篇 |
2007年 | 5篇 |
2006年 | 10篇 |
2005年 | 8篇 |
2004年 | 5篇 |
2003年 | 11篇 |
2002年 | 2篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 36篇 |
1997年 | 46篇 |
1996年 | 47篇 |
1995年 | 36篇 |
1994年 | 19篇 |
1993年 | 22篇 |
1992年 | 6篇 |
1991年 | 11篇 |
1990年 | 6篇 |
1989年 | 17篇 |
1988年 | 27篇 |
1987年 | 21篇 |
1986年 | 23篇 |
1985年 | 13篇 |
1984年 | 5篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 14篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 9篇 |
1976年 | 5篇 |
1975年 | 9篇 |
1974年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有580条查询结果,搜索用时 15 毫秒
101.
GTA Jombo EM Mbaawuaga AN Gyuse MNO Enenebeaku EE Okwori EJ Peters S Akpan F Odey EA Etukumana JT Akosu 《Asian Pacific journal of tropical medicine》2010,3(5):402-406
ObjectiveTo ascertain the socio-cultural factors influencing the rate of utilization of insecticide treated bed nets (ITNs) in a malaria endemic city of Makurdi, north central Nigeria.MethodsThe study was cross-sectional in nature using systematic sampling method to identify households. Both quantitative and qualitative data was generated from adult women using structured and semi structured questionnaires, and focused group discussions (FGDs) to obtain information on rate and patterns of utilization of ITNs. Information such as age, educational level, marital status, awareness or otherwise of the existence of malaria, and factors influencing rate of ownership and utilization of ITNs were obtained. FGDs were used to obtain qualitative information on rate of utilization of ITNs not captured in the questionnaires. Data obtained was analysed using Epi Info 6 statistical software.ResultsAmong the respondents interviewed, 97.0% (2 013/2 075) were aware of existence of malaria and 87.0% of these (1 751/2 013) would associate it with mosquitoes. The rate of ownership of any bed net, ITNs and untreated bed nets (UTNs) was 25.1%, 17.0% and 8.3%, respectively. Utilization of ITNs among children was 30.0% (112/373) and UTNs 12.9% (48/373). Positive contributors to ITNs utilization were literacy, enhanced economy, experience of marriage, and being gainfully employed (P<0.05); while negative contributors were ignorance, poverty and some cultural beliefs and values.ConclusionsA more synchronized advocacy should be carried out on the potential benefits of ITNs utilization and sustained. Also ITNs should be made available to the people of the community at minimal or no cost. 相似文献
102.
103.
Although the majority of fMRI studies exploit magnitude changes only, there is an increasing interest regarding the potential additive information conveyed by the phase signal. This integrated part of the complex number furnished by the MR scanners can also be used for exploring direct detection of neuronal activity and for thermography. Few studies have explicitly addressed the issue of the available signal stability in the context of phase time-series, and therefore we explored the spatial pattern of frequency specific phase fluctuations, and evaluated the effect of physiological noise components (heart beat and respiration) on the phase signal. Three categories of retrospective noise reduction techniques were explored and the temporal signal stability was evaluated in terms of a physiologic noise model, for seven fMRI measurement protocols in eight healthy subjects at 3 T, for segmented CSF, gray and white matter voxels. We confirmed that for most processing methods, an efficient use of the phase information is hampered by the fact that noise from physiological and instrumental sources contributes significantly more to the phase than to the magnitude instability. Noise regression based on the phase evolution of the central k-space point, RETROICOR, or an orthonormalized combination of these were able to reduce their impact, but without bringing phase stability down to levels expected from the magnitude signal. Similar results were obtained after targeted removal of scan-to-scan variations in the bulk magnetic field by the dynamic off-resonance in k-space (DORK) method and by the temporal off-resonance alignment of single-echo time series technique (TOAST). We found that spatial high-pass filtering was necessary, and in vivo a Gaussian filter width of 20 mm was sufficient to suppress physiological noise and bring the phase fluctuations to magnitude levels. Stronger filters brought the fluctuations down to levels dictated by thermal noise contributions, and for 62.5 mm3 voxels the phase stability was as low as 5 mrad (0.27°). In conditions of low SNRo and high temporal sampling rate (short TR); we achieved an upper bound for the phase instabilities at 0.0017 ppm, which is close to the dHb contribution to the GM/WM phase contrast. 相似文献
104.
HPM Smedts JH de Vries M Rakhshandehroo MF Wildhagen AC Verkleij-Hagoort EA Steegers RPM Steegers-Theunissen 《BJOG : an international journal of obstetrics and gynaecology》2009,116(3):416-423
Objective To study associations between maternal dietary and supplement intake of antioxidants vitamin E, retinol and congenital heart defects (CHDs).
Design Case–control study.
Setting Erasmus MC, University Medical Center Rotterdam, the Netherlands.
Population Participants were 276 case mothers of a child with CHD and 324 control mothers with their children.
Methods Food frequency questionnaires covering the intake of the previous 4 weeks were filled out at 16 months after the index pregnancy. Data were compared between cases and controls using the Mann–Whitney U test. Risk estimates for the association between CHD and dietary intake of vitamin E and retinol were estimated in a multivariable logistic regression model.
Main outcome measures Medians (5–95th percentile) and odds ratios with 95% CI.
Results Dietary vitamin E intake was higher in case mothers than in controls, 13.3 (8.1–20.4) and 12.6 (8.5–19.8) mg/day ( P = 0.05). CHD risk increased with rising dietary vitamin E intakes ( P -trend = 0.01). Periconception use of vitamin E supplements in addition to a high dietary vitamin E intake above 14.9 mg/day up to nine-fold increased CHD risk. Retinol intakes were not significantly different between the groups and not associated with CHD risk.
Conclusions High maternal vitamin E by diet and supplements is associated with an increased risk of CHD offspring. 相似文献
Design Case–control study.
Setting Erasmus MC, University Medical Center Rotterdam, the Netherlands.
Population Participants were 276 case mothers of a child with CHD and 324 control mothers with their children.
Methods Food frequency questionnaires covering the intake of the previous 4 weeks were filled out at 16 months after the index pregnancy. Data were compared between cases and controls using the Mann–Whitney U test. Risk estimates for the association between CHD and dietary intake of vitamin E and retinol were estimated in a multivariable logistic regression model.
Main outcome measures Medians (5–95th percentile) and odds ratios with 95% CI.
Results Dietary vitamin E intake was higher in case mothers than in controls, 13.3 (8.1–20.4) and 12.6 (8.5–19.8) mg/day ( P = 0.05). CHD risk increased with rising dietary vitamin E intakes ( P -trend = 0.01). Periconception use of vitamin E supplements in addition to a high dietary vitamin E intake above 14.9 mg/day up to nine-fold increased CHD risk. Retinol intakes were not significantly different between the groups and not associated with CHD risk.
Conclusions High maternal vitamin E by diet and supplements is associated with an increased risk of CHD offspring. 相似文献
105.
Background
Hydrocele is abnormal collection of serous fluid in the tunica vaginalis or a patent processus vaginalis. It is commonly encountered in our practice and often requires surgical treatment. However in our setting and in many underdeveloped countries, availability of general anaesthetic service is poor due to lack of trained personnel and equipment.Objectives
To ascertain the practicability and acceptability of hydrocelectomy under sedation and local anaesthesia in Nigerian adults with hydrocelePatients and Methods
A prospective study was carried out over a two year period on patients that had hydrocelectomy at the surgery unit of the Obafemi Awolowo University Teaching Hospitals Complex, Wesley Guild Hospital, Ilesa. Consecutive patients with diagnosis of hydrocele who consented had hydrocelectomy using intramuscular diazepam sedation and spermatic-cord block with 0.5% plane xylocaine and the scrotum infiltrated with same along the line of incision.Results
Fifty adult patients were studied: age range 15–94 years. Eighty percent of the patients had unilateral hydrocele and the commonest type was vaginal hydrocele (94%). All patients had hydrocelectomy, 96% were under local anaesthesia while 4% were converted to general anaesthesia. All patients except one prefer to have future surgery under such local anaesthesia and sedation.Conclusion
Hydrocelectomy under local anaesthesia and sedation is practicable and was tolerated and accepted by the adults patients studied. 相似文献106.
Igarashi S; Takiyama Y; Cancel G; Rogaeva EA; Sasaki H; Wakisaka A; Zhou YX; Takano H; Endo K; Sanpei K; Oyake M; Tanaka H; Stevanin G; Abbas N; Durr A; Rogaev EI; Sherrington R; Tsuda T; Ikeda M; Cassa E; Nishizawa M; Benomar A; Julien J; Weissenbach J; Tsuji S 《Human molecular genetics》1996,5(7):923-932
Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative
disorder caused by unstable expansion of a CAG repeat in the MJD1 gene at
14q32.1. To identify elements affecting the intergenerational instability
of the CAG repeat, we investigated whether the CGG/GGG polymorphism at the
3' end of the CAG repeat affects intergenerational instability of the CAG
repeat. The [expanded (CAG)n-CGG]/[normal (CAG)n- GGG] haplotypes were
found to result in significantly greater instability of the CAG repeat
compared to the [expanded (CAG)n- CGG]/[normal (CAG)n-CGG] or [expanded
(CAG)nGGG]/[normal (CAG)n-GGG] haplotypes. Multiple stepwise logistic
regression analysis revealed that the relative risk for a large
intergenerational change in the number of CAG repeat units (< -2 or >
2) is 7.7-fold (95% CI: 2.5-23.9) higher in the case of paternal
transmission than in that of maternal transmission and 7.4-fold (95% CI:
2.4-23.3) higher in the case of transmission from a parent with the
[expanded (CAG)n-CGG]/[normal (CAG)n-GGG] haplotypes than in that of
transmission from a parent with the [expanded (CAG)n-CGG]/[normal
(CAG)n-CGG] or [expanded (CAG)n- GGG]/[normal (CAG)n-GGG] haplotypes. The
combination of paternal transmission and the [expanded (CAG)n-CGG]/[normal
(CAG)n-GGG] haplotypes resulted in a 75.2-fold (95% CI: 9.0-625.0) increase
in the relative risk compared with that of maternal transmission and the
[expanded (CAG)n-CGG]/[normal (CAG)n-CGG] or [expanded (CAG)n- GGG]/[normal
(CAG)n-GGG] haplotypes. The results suggest that an inter- allelic
interaction is involved in the intergenerational instability of the
expanded CAG repeat.
相似文献
107.
Legendre C; Raphael M; Gras G; Lefevre EA; Feuillard J; Dormont D; Richard Y 《International immunology》1998,10(12):1847-1851
A centrofollicular hyperplasia is present within secondary lymphoid organs
during all the asymptomatic phase of the HIV disease. Although this
hyperplasia has been well characterized by histological studies, the nature
of the phenotypic alterations in B cell populations occurring within HIV+
lymphoid organs remains to be established. By immunohistochemistry, we thus
investigated whether a particular germinal center (GC) B cell population
was increased during HIV-induced hyperplasia and whether any phenotypic
change was specific to HIV-1 infection. As compared to normal tonsils
(three cases) and HIV- hyperplastic lymph nodes (eight patients), we
observed a loss of GC polarization in all HIV+ sections (11 patients), with
no more delineation between dark and light zones, as shown by Ki67, CD10,
CD77, CD95 and CD86 staining. In contrast to CD86 expression which remained
as intensive in HIV+ as in HIV- lymph nodes, CD80 staining was strongly
decreased in GC of HIV+ lymph nodes but not in their extrafollicular zones.
The loss of CD80 expression from CD19+ B cells was also observed by
cytometric analysis of cell suspensions of three HIV+ patients. Although we
found no evidence of an increase in a particular GC B cell subset in
HIV-1-induced hyperplasia, the strong GC disorganization observed may
induce impaired cell-cell interactions and thus participate in the loss of
CD80 antigen. In contrast to HIV- situations where CD80 and CD86 was
similarly expressed on B cells, the lower level of CD80 expression in HIV+
GC may favor Th2 T cell responses through CD86-CD28 interactions.
相似文献
108.
Between January and March 1986, 117 wives of insulation workers exposed to asbestos were screened by means of chest radiography, pulmonary function testing, and a detailed questionnaire. The final study group included 93 women over 40 years of age. Eighteen of these (19.4%) demonstrated pleural changes consistent with asbestos exposure, including pleural plaque (88.9%), diaphragm plaque (27.8%), pleural calcification (16.6%), and diffuse pleural thickening (5.5%). In statistical correlation between the groups with normal and abnormal radiographs, the only factor that proved significant was the year of first exposure (the duration of the latent period). Finally, radiographs of the husbands were compared for 17 of the 18 wives with radiographic abnormalities. Fourteen of the husbands (82%) demonstrated more severe radiographic changes than their wives. 相似文献
109.
110.
ES2 is a gene deleted in DiGeorge syndrome (DGS) and velocardiofacial
syndrome (VCFS) which has homologs in species as distant as Caenorhabditis
elegans and Drosophila . The function of ES2 is unknown, and the predicted
protein sequence does not contain motifs which suggest a particular role in
the developmental defects present in DGS and VCFS. Here we show that the
mouse homolog, Es2 , is transcribed in two forms resulting from the use of
alternative polyadenylation signals. Structural analysis programs predict
that the Es2 -encoded peptide has a coiled-coil domain, and transfection
experiments with an Es2 -green fluorescent protein (GFP) fusion construct
show that the peptide is recruited into the nucleus. Es2 is highly
expressed during mouse embryogenesis from E7 onwards. In situ hybridization
with an RNA probe revealed that the gene is widely expressed; however,
relatively higher expression was detected in the nervous system, with a
particularly high area of expression in a sub-region of the pons. The Es2
expression domain in the pons is shared with a Goosecoid-like gene ( Gscl)
which is located upstream of Es2 , and raises the possibility that the two
genes share regulatory elements and/or interact in this region of the
developing brain. This finding suggests that different genes in the deleted
region may be functionally related and might explain the occurrence of the
characteristic phenotype in patients with non-overlapping genetic lesions.
相似文献