全文获取类型
收费全文 | 262995篇 |
免费 | 13008篇 |
国内免费 | 493篇 |
专业分类
耳鼻咽喉 | 3407篇 |
儿科学 | 8005篇 |
妇产科学 | 5233篇 |
基础医学 | 37546篇 |
口腔科学 | 6063篇 |
临床医学 | 21753篇 |
内科学 | 57617篇 |
皮肤病学 | 6836篇 |
神经病学 | 23642篇 |
特种医学 | 8150篇 |
外国民族医学 | 109篇 |
外科学 | 33418篇 |
综合类 | 1259篇 |
现状与发展 | 1篇 |
一般理论 | 75篇 |
预防医学 | 23016篇 |
眼科学 | 5228篇 |
药学 | 18364篇 |
中国医学 | 778篇 |
肿瘤学 | 15996篇 |
出版年
2023年 | 1399篇 |
2022年 | 1173篇 |
2021年 | 4030篇 |
2020年 | 2456篇 |
2019年 | 4486篇 |
2018年 | 8163篇 |
2017年 | 5434篇 |
2016年 | 5495篇 |
2015年 | 6148篇 |
2014年 | 6605篇 |
2013年 | 10381篇 |
2012年 | 17897篇 |
2011年 | 17995篇 |
2010年 | 8975篇 |
2009年 | 6838篇 |
2008年 | 15315篇 |
2007年 | 16275篇 |
2006年 | 15024篇 |
2005年 | 14921篇 |
2004年 | 13959篇 |
2003年 | 12725篇 |
2002年 | 12186篇 |
2001年 | 6694篇 |
2000年 | 6804篇 |
1999年 | 6066篇 |
1998年 | 1181篇 |
1997年 | 971篇 |
1996年 | 892篇 |
1992年 | 3508篇 |
1991年 | 3156篇 |
1990年 | 3021篇 |
1989年 | 2753篇 |
1988年 | 2647篇 |
1987年 | 2456篇 |
1986年 | 2370篇 |
1985年 | 2165篇 |
1984年 | 1605篇 |
1983年 | 1378篇 |
1982年 | 825篇 |
1979年 | 1411篇 |
1978年 | 989篇 |
1977年 | 932篇 |
1975年 | 904篇 |
1974年 | 1099篇 |
1973年 | 1119篇 |
1972年 | 1045篇 |
1971年 | 1007篇 |
1970年 | 950篇 |
1969年 | 986篇 |
1968年 | 875篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
R G Jones J W Bass M E Weisse J M Vincent 《The Pediatric infectious disease journal》1991,10(8):557-559
We tested the urine of 30 infants 6 weeks to 7 months of age after they received standard 10-micrograms (0.5-ml) doses of HbOC (HibTITER) Haemophilus influenzae b (Hib) conjugate vaccine for the presence of Hib antigenuria using a commercially available latex particle agglutination assay (Directigen). Urines were collected within 1 hour, from 1 to 3 hours, at 24 hours and at 3, 6 and 9 days after vaccine administration and reactions were quantitated from 0 to 3+. In contrast to previous studies in older children which showed little or no antigenuria following HbOC vaccination, our study shows that in infants intense Hib antigenuria is evident within 2 to 3 hours and persists 3 days after vaccine administration and that less intense antigenuria may be detected in some infants for several days. With efficacious vaccines now being used in 2- to 6-month-old infants, invasive Hib disease may soon be limited to infants of this age just before their seroconversion. It should be recognized that antigenuria occurs for several days after vaccination with Hib conjugate vaccines and that it could be erroneously interpreted as evidence of invasive Hib infection. 相似文献
42.
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
43.
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
44.
45.
46.
47.
Mortality prognostic factors in chest injury 总被引:2,自引:0,他引:2
1,026 multiple trauma patients (P) were compared to P with chest injuries (PCT) (407). Severity indices were related to type of thoracic injury and mortality. The Injury Severity Score (ISS), Glasgow Coma Scale (GCS), Trauma Score (TS), CHOP, and the Respiratory Index (RI) were used. The mortality rate of P was 27.1% but increased to 32.9% for PCT (p less than 0.05). We noted that mortality rate was highly dependent on major chest trauma: 68.6% for flail chest (FC), 56% for lung contusion (LC), 42.3% for hemothorax (HA), and 38.1% for pneumothorax (PN). ISS and RI scores for PCT survivors were greater than ISS + RI scores for P survivors (p less than 0.05 and p less than 0.01). ISS values for LC, HA, and PN PCT survivors were greater than the ISS of P survivors (p less than 0.01). Nonsurviving PCTs, especially those with lung contusion, showed a highly significant increase in ISS and RI scores. 相似文献
48.
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
49.
A L Dannenberg T R Coté M J Kresnow J J Sacks C M Lipsitz E R Schmidt 《Public health reports (Washington, D.C. : 1974)》1993,108(2):212-217
Most of the nearly 1,000 fatal bicycle-related injuries annually could be prevented if riders used safety helmets. Helmet use by adult bicyclists has received relatively little attention because educational campaigns to promote helmet use generally focus on children. Helmet use by adult and child bicyclists at 120 suburban and rural sites in three Maryland counties was observed on two Saturdays in 1990-91 during an evaluation of the impact of a mandatory helmet law. Concordance or discordance of helmet use within various groups of bicyclists--adults only, adults with children, and children only--was recorded. Helmet use among 2,068 adult bicyclists was 49 percent, 51 percent, and 74 percent in the three counties. In two counties combined, 52 percent (365 of 706) of solo adult bicyclists wore helmets compared with only 5 percent (5 of 94) of solo child bicyclists (P < .001). Helmet use or nonuse was concordant among 87 percent of 277 adult-adult pairs, 94 percent of 50 child-child pairs, and 91 percent of 32 adult-child pairs of bicyclists observed. Concordance rates of helmet use or nonuse were similarly high among pairs of adult bicyclists of the same or mixed sexes. These data are consistent with the concept that both adults and children tend to adopt the helmet-wearing behaviors of their companions. Public health efforts focused on adults should encourage helmet use by adult bicyclists both to prevent head injuries and to provide a role model for children. 相似文献
50.