全文获取类型
收费全文 | 1392篇 |
免费 | 85篇 |
国内免费 | 20篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 78篇 |
妇产科学 | 14篇 |
基础医学 | 104篇 |
口腔科学 | 25篇 |
临床医学 | 173篇 |
内科学 | 187篇 |
皮肤病学 | 42篇 |
神经病学 | 88篇 |
特种医学 | 194篇 |
外科学 | 205篇 |
综合类 | 58篇 |
预防医学 | 207篇 |
眼科学 | 11篇 |
药学 | 74篇 |
中国医学 | 6篇 |
肿瘤学 | 26篇 |
出版年
2022年 | 7篇 |
2021年 | 11篇 |
2019年 | 13篇 |
2018年 | 13篇 |
2017年 | 11篇 |
2016年 | 21篇 |
2015年 | 19篇 |
2014年 | 42篇 |
2013年 | 37篇 |
2012年 | 46篇 |
2011年 | 56篇 |
2010年 | 51篇 |
2009年 | 31篇 |
2008年 | 36篇 |
2007年 | 46篇 |
2006年 | 43篇 |
2005年 | 43篇 |
2004年 | 43篇 |
2003年 | 42篇 |
2002年 | 41篇 |
2001年 | 36篇 |
2000年 | 58篇 |
1999年 | 62篇 |
1998年 | 52篇 |
1997年 | 47篇 |
1996年 | 41篇 |
1995年 | 28篇 |
1994年 | 30篇 |
1993年 | 27篇 |
1992年 | 25篇 |
1991年 | 60篇 |
1990年 | 35篇 |
1989年 | 44篇 |
1988年 | 29篇 |
1987年 | 29篇 |
1986年 | 26篇 |
1985年 | 19篇 |
1984年 | 27篇 |
1983年 | 24篇 |
1981年 | 11篇 |
1980年 | 12篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1975年 | 11篇 |
1974年 | 7篇 |
1973年 | 6篇 |
1972年 | 7篇 |
1970年 | 7篇 |
排序方式: 共有1497条查询结果,搜索用时 0 毫秒
71.
Jennifer R. Dowd Michael A. Quinn Robert Rome Hoon Koh 《The Australian & New Zealand journal of obstetrics & gynaecology》1993,33(4):404-407
Summary: A retrospective study of 264 patients with a pelvic mass who had a preoperative serum CA 125 level performed was undertaken to compare the sensitivity, specificity and predictive values of this test as a predictor of malignancy, compared with clinical impression and ultrasonography (USG). The values were calculated for each parameter alone and in combination, and the effect of menopausal status, histological type and stage of disease was also assessed. The results indicate that in postmenopausal women with a pelvic mass, a CA 125 level should be performed and the patient referred to a gynaecological oncologist if the value is raised. In contrast both CA 125 and USG should be performed in the premenopausal woman to allow appropriate referral. In this study a CA 125 level of 35 u/ml or more correctly identified malignancy in 90% of postmenopausal women. 相似文献
72.
Unilateral haemorrhagic parenchymal lesions in the preterm infant: shape, site and prognosis 总被引:2,自引:0,他引:2
KJ Rademaker F Groeneadaal GH Jansen P Eken LS De Vries 《Acta paediatrica (Oslo, Norway : 1992)》1994,83(6):602-608
Rademaker KJ, Groenendaal F, Jansen GH, Eken P, de Vries LS. Unilateral haemorrhagic parenchymal lesions in the preterm infant: shape, site and prognosis. Acta Pædiatr 1994;83:602–8. Stockholm. ISSN 0803–5253 In a prospective cranial ultrasound study of 544 infants with a gestational age of 32 weeks or less, 20 (3.6%) infants were diagnosed as having a unilateral parenchymal lesion (PL). Based on the shape of the PL and the evolution on ultrasound, the infants were divided into three groups: group I consisted of 11 infants, in whom the PL was triangular/fan-shaped and separate from the ventricle. The PL evolved into small cystic lesions; group II comprised 3 infants who had a PL with a similar shape, but partially communicating with the ventricle; group III consisted of 6 infants who had a globular-shaped lesion in communication with the ventricle. In groups II and III, the PL evolved into one porcncephalic cyst. The PL was considered to be due to venous infarction in all cases with intraventricular haemorrhage preceding the PL in 7 cases. Sixteen infants survived. A postmortem was performed in 2 of the 4 infants who died, confirming the diagnosis of venous infarction. Neurologicdl sequelae were present in only 2 cases in the first group, while all 6 survivors of the other two groups developed mild to severe hemiplegia. Long-term follow-up was not always available and 4 of the 18 survivors were still less than 18 months when last seen. In 9 of the 11 infants in group I, the PL was localized in the frontoparietal region, while in 8 of the 9 infants in group II or III, the PL was beyond the trigone in the occipital region. The outcome of the unilateral PL is not always unfavourable. It was evident that not only the shape of the lesion and whether or not there was communication with the lateral ventricle, but also the site of the lesion (whether or not it extended into the occipital periventricular white matter) appeared to be important with regard to neurodevelopmental outcome. 相似文献
73.
74.
Dowd MD 《Current opinion in pediatrics》1999,11(6):578-582
Unintentional injuries are the leading cause of death for children and adolescents in the United States, and they create a significant burden of disability and financial cost. If motor vehicle-associated injuries are not considered, children are most commonly injured in their home and play environments. The reduction over the past 20 years in childhood deaths related to motor vehicle injury has been significant, but rates of childhood death due to other causes, such as firearms, have increased. This review focuses on several categories of injuries other than motor vehicle injuries and highlights a few recent successful community- and practice-based injury-prevention programs. In addition, recent epidemiologic studies describing risk factors for injury-related death are discussed. Injuries due to interpersonal violence and motor vehicles are covered elsewhere. 相似文献
75.
This study examined the morbidity experience from 1981 to 1988 of a prospective cohort of 3422 refinery and petrochemical plant employees from the Shell Deer Park manufacturing complex. The morbidity data for this study, which include all illness and absence records in excess of five days, were extracted from the morbidity section of the Shell health surveillance system. Standardised morbidity ratios (SMRs) of disease prevalence in this cohort were calculated using an internal comparison group of all manufacturing employees of the Shell Oil Company. Among production employees, the overall morbidity was statistically significantly higher (SMR = 109) than that of the comparison group. Illness due to hypertension (SMR = 144), haemorrhoids (SMR = 149), diseases of the nervous system (SMR = 120), respiratory system (SMR = 108), and digestive system (SMR = 117) were also raised for this group. The increased risk due to these medical conditions does not appear to be associated with occupational factors. Lymphatic and haematopoietic tissue neoplasms were raised (SMR = 124), but were based on only four cases. 相似文献
76.
77.
P Dowd Z B Zheng 《Proceedings of the National Academy of Sciences of the United States of America》1995,92(18):8171-8175
Vitamin E in the reduced, alpha-tocopherol form shows very modest anticlotting activity. By contrast, vitamin E quinone is a potent anticoagulant. This observation may have significance for field trials in which vitamin E is observed to exhibit beneficial effects on ischemic heart disease and stroke. Vitamin E quinone is a potent inhibitor of the vitamin K-dependent carboxylase that controls blood clotting. A newly discovered mechanism for the inhibition requires attachment of the active site thiol groups of the carboxylase to one or more methyl groups on vitamin E quinone. The results from a series of model reactions support this interpretation of the anticlotting activity associated with vitamin E. 相似文献
78.
This study investigated the characteristics of computer-based case simulations (CCS) that may be associated with case difficulty. Difficulty was defined as the average rating by physicians of examinee performance on a nine-point scale or the passing rate on the cases. Two data sets were used, one from an administration of 18 cases, the other from an administration of 22 cases with 13 cases used on both occasions. Stepwise regression procedures were used separately for case properties and for analytic scoring of key variables to identify the best sets of predictors of case difficulty. Because of the small number of cases, regression results were evaluated for consistency across both data sets and both difficulty measures. For key variables, the best set of predictors included the number of different serious errors of commission, risk items, and benefit items. In general, cases were more difficult for higher values of these variables. For case variables, the only consistent variable was the length of the paragraph that provided patient history, with longer paragraphs associated with more difficult cases. Other variables were less consistent, but were often related to the structure of the simulation or the severity of the patient condition. Although the findings for case variables were limited, the analyses were very helpful in illuminating the interconnections among the variables within cases. 相似文献
79.
Ultrasonic features of 21 surgically confirmed pyogenic liver abscesses in 18 patients were analyzed. Typical lesions were round or ovoid with a discrete, irregular, echo-poor margin. The number and intensity of internal echoes and sound transmission were variable. Such lesions can be aspirated percutaneously for definitive preoperative diagnosis. Pyogenic liver abscesses appear to have more ragged walls and are less frequently elliptical or multilocular than abscesses elsewhere in the abdomen. 相似文献
80.