全文获取类型
收费全文 | 172565篇 |
免费 | 8281篇 |
国内免费 | 596篇 |
专业分类
耳鼻咽喉 | 2243篇 |
儿科学 | 5296篇 |
妇产科学 | 4462篇 |
基础医学 | 23341篇 |
口腔科学 | 5609篇 |
临床医学 | 12435篇 |
内科学 | 41331篇 |
皮肤病学 | 5089篇 |
神经病学 | 14579篇 |
特种医学 | 4675篇 |
外国民族医学 | 36篇 |
外科学 | 21609篇 |
综合类 | 955篇 |
一般理论 | 50篇 |
预防医学 | 16625篇 |
眼科学 | 2881篇 |
药学 | 11588篇 |
中国医学 | 630篇 |
肿瘤学 | 8008篇 |
出版年
2023年 | 1010篇 |
2022年 | 2109篇 |
2021年 | 4407篇 |
2020年 | 2350篇 |
2019年 | 3949篇 |
2018年 | 6348篇 |
2017年 | 4038篇 |
2016年 | 3485篇 |
2015年 | 3689篇 |
2014年 | 5277篇 |
2013年 | 7230篇 |
2012年 | 10647篇 |
2011年 | 11220篇 |
2010年 | 6215篇 |
2009年 | 5639篇 |
2008年 | 9183篇 |
2007年 | 9515篇 |
2006年 | 9026篇 |
2005年 | 9173篇 |
2004年 | 8404篇 |
2003年 | 7887篇 |
2002年 | 7524篇 |
2001年 | 4820篇 |
2000年 | 5062篇 |
1999年 | 4185篇 |
1998年 | 1465篇 |
1997年 | 1036篇 |
1996年 | 958篇 |
1995年 | 843篇 |
1994年 | 691篇 |
1993年 | 691篇 |
1992年 | 2052篇 |
1991年 | 1893篇 |
1990年 | 1762篇 |
1989年 | 1532篇 |
1988年 | 1376篇 |
1987年 | 1348篇 |
1986年 | 1226篇 |
1985年 | 1135篇 |
1984年 | 826篇 |
1983年 | 730篇 |
1979年 | 692篇 |
1978年 | 515篇 |
1975年 | 534篇 |
1974年 | 585篇 |
1973年 | 591篇 |
1972年 | 532篇 |
1971年 | 517篇 |
1970年 | 495篇 |
1969年 | 474篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
This study investigates the contribution of body fat stores on the age-associated increase in serum cholesterol and triglyceride levels. Percentage of body fat was measured by hydrostatic weighing, and serum cholesterol, triglyceride, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol levels were determined in a sample of 472 healthy men and women ages 18-50 years. In both sexes, body fat mass was significantly correlated with serum cholesterol (r = 0.21 in men and r = 0.24 in women, P less than 0.01) and triglyceride (r = 0.33 in men and r = 0.24 in women, P less than 0.01) levels. After adjustment for the association between age and serum cholesterol, no correlation was observed between body fat mass and serum cholesterol (r = 0.01 in men and r = 0.09 in women). After correction for age, serum triglyceride levels remained significantly correlated with body fat mass (r = 0.26 and r = 0.17 in men and women, respectively, P less than 0.05). As body fat also increases with age, the possibility that a partial correlation coefficient procedure eliminated a portion of the age effect mediated by an age-related increase in fat, was addressed by performing further analyses. Within each sex subsample two sets of analyses were performed on (a) three groups of subjects individually paired for age but with different levels of body fat stores, and (b) three groups of subjects paired for the amount of body fat but differing in age.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
82.
M. A. García-Pérez C. Climent P. Briones M. A. Vilaseca M. Rodés V. Rubio 《Journal of inherited metabolic disease》1997,20(6):769-777
Mutations P225L and P225R were identified in codon 225 of the gene for ornithine transcarbamylase (OTC) in two patients with the neonatal form of OTC deficiency. The mutations occur at a CpG dinucleotide and eliminate a unique MspI restriction site in exon 7 of the OTC gene. They do not alter existing splice sites or create new sites, as judged from the nucleotide sequence. Both mutations are associated with undetectable levels of OTC antigen in liver homogenates, and with either complete lack of OTC activity (P225R mutation) or very small residual activity (0.15% of normal in the P225L mutation). The residual activity observed with P225L exhibits normal pH dependence, little or no increases in the Km values for ornithine and carbamoyl phosphate and normal stability at either 37°C or, in the presence of 0.66 mol/L urea, at 0°C. The latter conditions were used to examine whether the P225L mutation favours dissociation of the active OTC trimer. Given the normal stability and lack of tendency to dissociation of the mutant enzyme, it appears likely that the dramatic reduction in the level of OTC protein is due to inefficient conversion of the mutant OTC precursor polypeptide (pOTC) into the correctly localized, appropriately folded, mature enzyme trimer, suggesting degradation of pOTC in transit to the mitochondria. 相似文献
83.
84.
85.
Uptake of Adriamycin in tumour and surrounding brain tissue in patients with malignant gliomas 总被引:1,自引:0,他引:1
H. von Holst E. Knochenhauer H. Blomgren V. P. Collins L. Ehn M. Lindquist G. Norén C. Peterson 《Acta neurochirurgica》1990,104(1-2):13-16
Summary Eight patients with malignant gliomas verified on CT scan, received an intravenous injection of 50 mg of Adriamycin R, 24 hours prior to surgical removal of the tumour. Peroperatively, both tumour and surrounding tissue specimens were obtained for determination of the tissue concentrations of Adriamycin and its reduced metabolite Adriamycinol. It was found that Adriamycin could be detected in tumour tissue from all patients. The concentration varied between 0,9 and 4,6 nmol/g tissue. In contrast, Adriamycin could only be detected in surrounding brain tissue from one patient.In anin vitro study a human malignant glioma cell line (U-251 MG) was exposed to various concentrations of Adriamycin for 24 hours. It was found that an intracellular drug concentration above 30 nmol/g cells caused a concentration dependent inhibition of cell growth. Thus, it is likely that the poor effect of Adriamycin on patients with malignant gliomas is due to an ineffective drug accumulation in the tumour tissue. 相似文献
86.
87.
88.
Recurrence, progression and survival in bladder cancer. A retrospective analysis of 232 patients with greater than or equal to 5-year follow-up 总被引:1,自引:0,他引:1
A retrospective study of 232 bladder tumours with minimum follow-up 5 years is presented. The carcinoma was superficial in 66%, muscle-invasive in 31% and could not be staged in 3%. Primary treatment was mainly transurethral resection for superficial tumour, but was cystectomy or radiotherapy in 22 of 29 T1 G3. Of the superficial tumours, 71% recurred. Progression to higher T stage occurred in 15% of Ta and 29% of T1 tumours, and half of these patients died of bladder cancer. The corrected 5-year survival rates in grades 1, 2A, 2B and 3-4 were 96, 84, 64 and 43%, and in stages Ta, T1, T2 and T3 they were 94, 69, 40 and 31%. All patients with T4 tumour died within 4 years. Among the 45 patients with 40 Gy irradiation + cystectomy, the corrected 5-year survival rate was 83% in superficial and 64% in muscle-invasive tumours, and among the 38 with radical radiotherapy the rates in T1-3 were 46, 36 and 13%. Transurethral resection was successful in most Ta cases. Most T1 tumours were, like T2-4, of higher grade than Ta. Prognosis was worse in T1 than in Ta. After progression to muscle-invasive disease, even during close follow-up the outlook was poor, as poor as for patients with primary muscle-invasive disease. 相似文献
89.
Mikael Hellström Bo Jacobsson Ulf Jodal Jan Winberg Anders Odén 《Pediatric nephrology (Berlin, Germany)》1987,1(3):269-275
This study presents the result of 12–21 years' follow-up in a group of children with neonatal urinary tract infection (onset within 1 month after birth) in whom early renal growth retardation was noted without concomitant classical renal scarring. In all cases the neonatal infection was diagnosed and treated within a few days of onset and the patients were closely supervised thereafter. Renal length, parenchymal thickness and area were measured at urography. At first follow-up (22 children, mean age 4.1 years) a significant reduction of renal parenchymal thickness was noted. Long-term follow-up (18 patients, mean age 17 years) demonstrated a normalization of renal size in the entire group, although less complete in the subgroup with reflux. There were two major findings in the present study. Firstly, renal growth retardation was seen after neonatal infection, both with and without reflux. Secondly, normalization of renal size in previously small kidneys was demonstrated, suggesting that growth retardation can be a reversible phenomenon. The tendency for such normalization was slightly more marked in children without reflux. Reduction of parenchymal thickness without calyceal deformity, therefore, does not necessarily mean irreversible damage, and differentiation between permanent scarring and temporary growth retardation can thus only be made at later follow-up, possibly not until after puberty. The demonstration of renal growth retardation in spite of early diagnosis and treatment emphasizes the great vulnerability of the kidney in the newborn. 相似文献
90.
A. Jaén J. Sunyer X. Basagaña S. Chinn† J. P. Zock J. M. Antó‡ P. Burney† 《Clinical and experimental allergy》2002,32(12):1713-1719
BACKGROUND: The role of atopy in the evolution to chronic obstructive disease remains controversial. AIM: We aimed to assess the association between individual sensitization to common allergens and lung function. METHOD: We analysed data from 12,687 subjects aged 20 to 44 years, from 34 centres in 15 countries participating in the European Community Respiratory Health Survey (ECRHS). Participants performed a blood test, lung function test, methacholine challenge, and answered an administered questionnaire. The relationships between specific IgE, FEV1 and FEV1/FVC ratio were assessed for each study centre stratified by sex, followed by random effects meta-analysis. RESULTS: Asthmatics sensitized to house dust mite had a lower FEV1 (-119 mL in women and -112 mL in men) and FEV1/FVC ratio (-1.95%, and -2.48%) than asthmatics without sensitization. Asthmatics sensitized to cat had a lower FEV1 (statistically significant for women only) and a lower FEV1/FVC ratio. Asthmatic women sensitized to grass had a lower FEV1 and a lower ratio, and those sensitized to Cladosporium had a lower FEV1. A weak association was found with sensitization to cat and to Cladosporium among non-asthmatic women, which disappeared after adjusting for BHR. CONCLUSION: We conclude that atopy was related to a lower lung function, which was only apparent among asthmatics. This relationship was explained by specific sensitization to cat and to house dust mite, the latter being homogeneous across areas. 相似文献