全文获取类型
收费全文 | 1249篇 |
免费 | 87篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 41篇 |
妇产科学 | 13篇 |
基础医学 | 195篇 |
口腔科学 | 34篇 |
临床医学 | 190篇 |
内科学 | 220篇 |
皮肤病学 | 34篇 |
神经病学 | 151篇 |
特种医学 | 49篇 |
外科学 | 180篇 |
综合类 | 5篇 |
一般理论 | 1篇 |
预防医学 | 96篇 |
眼科学 | 4篇 |
药学 | 66篇 |
肿瘤学 | 50篇 |
出版年
2023年 | 5篇 |
2022年 | 15篇 |
2021年 | 36篇 |
2020年 | 17篇 |
2019年 | 30篇 |
2018年 | 36篇 |
2017年 | 20篇 |
2016年 | 44篇 |
2015年 | 37篇 |
2014年 | 51篇 |
2013年 | 69篇 |
2012年 | 103篇 |
2011年 | 91篇 |
2010年 | 62篇 |
2009年 | 57篇 |
2008年 | 74篇 |
2007年 | 76篇 |
2006年 | 84篇 |
2005年 | 64篇 |
2004年 | 53篇 |
2003年 | 54篇 |
2002年 | 44篇 |
2001年 | 15篇 |
2000年 | 5篇 |
1999年 | 12篇 |
1998年 | 13篇 |
1997年 | 14篇 |
1996年 | 11篇 |
1995年 | 14篇 |
1994年 | 7篇 |
1993年 | 7篇 |
1992年 | 10篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 4篇 |
1983年 | 5篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 5篇 |
1972年 | 15篇 |
1971年 | 11篇 |
1970年 | 5篇 |
1969年 | 4篇 |
1968年 | 4篇 |
1967年 | 4篇 |
1965年 | 3篇 |
排序方式: 共有1337条查询结果,搜索用时 15 毫秒
71.
Prognostic significance of recurrent chromosomal aberrations detected by comparative genomic hybridization in sporadic colorectal cancer 总被引:6,自引:0,他引:6
De Angelis PM Stokke T Beigi M Mjåland O Clausen OP 《International journal of colorectal disease》2001,16(1):38-45
Colorectal carcinomas are characterized by frequent recurrent gains and losses of chromosomal material, especially gains of chromosome arms 20q and 13q, and losses of chromosome arms 18q and 4q. These may be important in the development and progression of colorectal carcinomas. Chromosomal aberrations detected by comparative genomic hybridization in 67 sporadic colorectal carcinomas were examined for their possible associations with patient survival. Dukes' stage, tumor DNA ploidy status, and TP53 genotype/phenotype were also examined for the same. Patients with losses of chromosomal arms 1p, 4q, 8p, 14q, or 18q or gain of chromosomal arm 20q had significantly shorter survival times than those without these aberrations (univariate relative risk 3.45, 2.71, 3.32, 3.26, 3.32, 3.91, respectively), as did patients with more than six chromosomal aberrations per tumor than those with fewer than six aberrations (univariate relative risk 3.26, P = 0.013). DNA aneuploidy and Dukes' stage C + D resulted in poor patient survival (univariate relative risk 3.58, 3.39, respectively). Dukes' stage C + D, 1p loss and 8p loss emerged as the only independent prognostic parameters (relative risk 3.22, 2.53, 2.45, respectively) when entered into multivariate survival analysis together with other significant parameters from univariate survival analysis. Loss of chromosome arm 1p, 4q, 8p, 14q, or 18q or gain of chromosome arm 20q thus results in shortened survival times in colorectal cancer patients. 1p loss and 8p loss were shown to be independent predictors of poor prognosis. 相似文献
72.
73.
Marte S. Heiberg Bjrn‐Yngvar Nordvg Knut Mikkelsen Erik Rdevand Cecilie Kaufmann Petter Mowinckel Tore K. Kvien 《Arthritis \u0026amp; Rheumatology》2005,52(8):2506-2512
Objective
To compare the effectiveness of tumor necrosis factor (TNF)–blocking agents (etanercept and infliximab) in patients with rheumatoid arthritis (RA) and patients with ankylosing spondylitis (AS).Methods
Data from an ongoing longitudinal, observational study in Norway were used to assess changes in health‐related quality of life (HRQOL) in patients with RA (n = 291) and AS (n = 62). Patients received anti‐TNF therapy, and changes in scores on the Short Form 36 (SF‐36), SF‐6D, modified Health Assessment Questionnaire, and visual analog scales for patients' assessments of pain, fatigue, and global status from baseline to followup examinations at 3 and 6 months were compared. Data were adjusted for age, sex, and baseline values and are presented as crude estimates as well as standardized response means.Results
Both groups had improvements in all measures at 3 and 6 months. At 3 months, the changes were significantly better in the AS group compared with the RA group for all measures except the SF‐36 social functioning scores. At 6 months, all changes were numerically greater in the AS group. Differences were significant for the SF‐36 role emotional scores and were borderline significant for the SF‐36 physical functioning, role physical, and vitality scores and for the SF‐6D scores.Conclusion
In this real‐life setting, patients with AS experienced improvement in HRQOL that was comparable to, and sometimes greater than, that observed in RA patients. These results support the idea that patients with AS should have the same access to TNF‐blocking agents as patients with RA.74.
Stafström M Ostergren PO Larsson S Lindgren B Lundborg P 《Addiction (Abingdon, England)》2006,101(6):813-823
AIMS: To evaluate a 3-year community intervention programme by measuring changes in drinking patterns in a 15-16-year-old population. DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS: The action programme included five demand-reducing and one supply-reducing interventions. Cross-sectional, non-repeated data were collected from a questionnaire distributed in classrooms from 1999 to 2001 and 2003 (n = 1376, 724 boys and 652 girls; response rate = 92.3%). Stepwise logistic regression analyses were used to determine the relationship between different risk factors and excessive drinking, heavy episodic drinking, purchaser of alcohol and alcohol provided by parents. The results from the intervention community were also compared with similar Swedish cross-sectional data sets. FINDINGS: The results of our analyses indicated a decrease in harmful drinking behaviour in Trelleborg when comparing baseline with postintervention measurements. The comparison with other studies showed that the changes in these indicators were more rapid and consistent in Trelleborg. Finally, the multivariable logistic regression analyses showed that the outcomes were not likely to be attributed to changes in environmental factors. CONCLUSIONS: We concluded that a community action programme based on the systems approach reduced hazardous alcohol consumption effectively among adolescents in Trelleborg. 相似文献
75.
Temporary loss of perivascular aquaporin-4 in neocortex after transient middle cerebral artery occlusion in mice 下载免费PDF全文
Frydenlund DS Bhardwaj A Otsuka T Mylonakou MN Yasumura T Davidson KG Zeynalov E Skare O Laake P Haug FM Rash JE Agre P Ottersen OP Amiry-Moghaddam M 《Proceedings of the National Academy of Sciences of the United States of America》2006,103(36):13532-13536
The aquaporin-4 (AQP4) pool in the perivascular astrocyte membranes has been shown to be critically involved in the formation and dissolution of brain edema. Cerebral edema is a major cause of morbidity and mortality in stroke. It is therefore essential to know whether the perivascular pool of AQP4 is up- or down-regulated after an ischemic insult, because such changes would determine the time course of edema formation. Here we demonstrate by quantitative immunogold cytochemistry that the ischemic striatum and neocortex show distinct patterns of AQP4 expression in the reperfusion phase after 90 min of middle cerebral artery occlusion. The striatal core displays a loss of perivascular AQP4 at 24 hr of reperfusion with no sign of subsequent recovery. The most affected part of the cortex also exhibits loss of perivascular AQP4. This loss is of magnitude similar to that of the striatal core, but it shows a partial recovery toward 72 hr of reperfusion. By freeze fracture we show that the loss of perivascular AQP4 is associated with the disappearance of the square lattices of particles that normally are distinct features of the perivascular astrocyte membrane. The cortical border zone differs from the central part of the ischemic lesion by showing no loss of perivascular AQP4 at 24 hr of reperfusion but rather a slight increase. These data indicate that the size of the AQP4 pool that controls the exchange of fluid between brain and blood during edema formation and dissolution is subject to large and region-specific changes in the reperfusion phase. 相似文献
76.
Use of robotized DNA isolation and real-time PCR to quantify and identify close correlation between levels of Neisseria meningitidis DNA and lipopolysaccharides in plasma and cerebrospinal fluid from patients with systemic meningococcal disease 下载免费PDF全文
Øvstebø R Brandtzaeg P Brusletto B Haug KB Lande K Høiby EA Kierulf P 《Journal of clinical microbiology》2004,42(7):2980-2987
The present study, using robotized DNA isolation and quantitative PCR based on the Neisseria meningitidis-specific capsular transport A gene, demonstrates the ease, rapidity, specificity, and sensitivity of quantifying neisserial DNA in plasma (n = 65) and cerebrospinal fluid (CSF) (n = 12) from patients with systemic meningococcal disease. We found a close correlation between the levels of neisserial DNA and lipopolysaccharides in plasma (r = 0.905) and in CSF (r = 0.964). The median concentration of neisserial DNA in plasma in 23 patients with persistent shock was 2 x 10(7) copies/ml, versus <10(3) copies/ml in 42 nonshock patients. Furthermore, quantitative PCR made possible estimates of the total number of meningococci in plasma, as opposed to conventional blood cultures, suggesting about 1,000 dead meningococci for every viable bacterium. Finally, with logistic regression analyses, neisserial DNA may predict a patient's disease severity and outcome at hospital admission. The number of meningococci in plasma and CSF appears to be the main determinant of the lipopolysaccharide levels, clinical presentation, and outcome. 相似文献
77.
A gene homologous to Saccharomyces cerevisiae SNF1 appears to be essential for the viability of Candida albicans. 下载免费PDF全文
The SNF1 gene of Saccharomyces cerevisiae (ScSNF1) is essential for the derepression of catabolic repression. We report here the isolation and characterization of an SNF1 homolog from Candida albicans (CaSNF1) which is apparently essential for the viability of this organism. The putative amino acid sequence of CaSNF1 has 68% identity with that of ScSNF1 and can restore the S. cerevisiae snf1 delta mutant's ability to utilize sucrose. Disruption of one of the CaSNF1 alleles resulted in morphological changes and decreased growth rates but did not modify the carbon source utilization pattern. Repetitive unsuccessful attempts to generate a snf1/snf1 homozygote by disruption of the second allele, using various vectors and approaches, suggest the lethal nature of this mutation. Integration into the second allele was possible only when a full-length functional SNF1 sequence was reassembled, further supporting this hypothesis and indicating that the indispensability of Snf1p prevented the isolation of snf1/snf1 mutants. The mutant bearing two disrupted SNF1 alleles and the SNF1 functional sequence maintained its ability to utilize sucrose and produced stellate colonies with extensive hyphal growth on agar media. It was demonstrated that in a mouse model, the virulences of this mutant and the wild-type strain are similar, suggesting that hyphal growth in vitro is not an indicator for higher virulence. 相似文献
78.
Geir Håland Karin Cecilie Lødrup Carlsen Petter Mowinckel Monica Cheng Munthe-Kaas Chandra Sekhar Devulapalli Sveinung Berntsen Kai-Håkon Carlsen 《Pediatric allergy and immunology》2009,20(3):254-260
The causal relationship between lower respiratory tract infections (LRIs) in early life and reduced lung function later in childhood is unsettled. Therefore, we assessed whether LRIs the first 2 yr of life influenced lung function development from birth to school age. In the prospective Oslo birth cohort, ‘the Environment and Childhood Asthma (ECA) study’ lung function was measured at birth in 802 infants by tidal flow volume loops and in 664 infants by passive respiratory mechanics and half yearly questionnaires, including LRI questions, were completed until 2 yr of age. The present study includes 607 children with information about LRIs the first 2 yr of life and successfully forced expiratory flow (FEF) volume measurements at the 10‐yr follow‐up assessment. At 10 yr of age, FEF at 50% of forced vital capacity (FEF50) (mean 95% confidence interval) was reduced in children with at least one bronchiolitis (85.0, 80.6–89.5, p = 0.020) or bronchitis (86.2, 82.6–89.8, p = 0.030) or ≥3 LRIs (83.4, 78.1–88.8, p = 0.017) when compared with no LRIs (90.6, 88.8–92.5) by 2 yr of life. The effects were significant in girls only when stratifying for gender. Among girls with later bronchiolitis compliance of the respiratory system (3.64, 3.17–4.10 vs. 4.18, 3.98–4.37, p = 0.031) and the ratio of time to peak tidal expiratory flow to total expiratory time (tPTEF/tE) measured at birth was significantly reduced (0. 26, 0.23–0.29 vs. 0.32, 0.30–0.33, p = 0.005) when compared with children with no LRIs. Change in lung function from birth (by tPTEF/tE) to 10 yr of age was not significantly associated with LRIs the first 2 yr of life, and LRIs by 2 yr of life were not significantly associated with lung function at 10 yr of age in regression analyses including lung function at birth and other possible predictors of lung function at 10 yr. In our study, LRIs during the first 2 yr of life did not impair lung function development from birth until 10 yr of age. 相似文献
79.
80.