全文获取类型
收费全文 | 21687篇 |
免费 | 1347篇 |
国内免费 | 257篇 |
专业分类
耳鼻咽喉 | 327篇 |
儿科学 | 399篇 |
妇产科学 | 527篇 |
基础医学 | 3158篇 |
口腔科学 | 431篇 |
临床医学 | 1883篇 |
内科学 | 4551篇 |
皮肤病学 | 916篇 |
神经病学 | 1615篇 |
特种医学 | 1130篇 |
外科学 | 3357篇 |
综合类 | 172篇 |
现状与发展 | 1篇 |
一般理论 | 5篇 |
预防医学 | 734篇 |
眼科学 | 434篇 |
药学 | 1661篇 |
中国医学 | 263篇 |
肿瘤学 | 1727篇 |
出版年
2023年 | 143篇 |
2022年 | 350篇 |
2021年 | 762篇 |
2020年 | 378篇 |
2019年 | 518篇 |
2018年 | 690篇 |
2017年 | 550篇 |
2016年 | 738篇 |
2015年 | 1008篇 |
2014年 | 1265篇 |
2013年 | 1265篇 |
2012年 | 1948篇 |
2011年 | 1943篇 |
2010年 | 1173篇 |
2009年 | 921篇 |
2008年 | 1314篇 |
2007年 | 1251篇 |
2006年 | 1084篇 |
2005年 | 1034篇 |
2004年 | 844篇 |
2003年 | 659篇 |
2002年 | 655篇 |
2001年 | 442篇 |
2000年 | 419篇 |
1999年 | 324篇 |
1998年 | 137篇 |
1997年 | 101篇 |
1996年 | 96篇 |
1995年 | 79篇 |
1994年 | 66篇 |
1993年 | 34篇 |
1992年 | 124篇 |
1991年 | 110篇 |
1990年 | 101篇 |
1989年 | 64篇 |
1988年 | 58篇 |
1987年 | 67篇 |
1986年 | 53篇 |
1985年 | 53篇 |
1984年 | 33篇 |
1980年 | 22篇 |
1979年 | 31篇 |
1977年 | 30篇 |
1976年 | 24篇 |
1975年 | 25篇 |
1974年 | 28篇 |
1973年 | 26篇 |
1972年 | 30篇 |
1970年 | 23篇 |
1969年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
21.
The determination of a unicellular or a multicellular origin of a tumor is an important due for understanding its etiology. To investigate this issue, we performed clonality assay of cervix cancer using polymerase chain reaction based on highly polymorphic locus of the androgen receptor gene, in which methylation of DNA correlates with inactivation of X chromosome. DNA samples were obtained from formalin-fixed, paraffin-embedded tissue of 20 invasive epidermoid carcinomas and 10 carcinoma in situ. Seven of ten carcinoma in situ, heterozygous for the androgen receptor locus, were monoclonal pattern. Among twenty invasive epidermoid carcinomas, eighteen of which showed heterozygous, twelve were monoclonal pattern and six were polyclonal pattern. We conclude that carcinoma in situ arises from a single cell. In invasive epidermoid carcinoma, most cases were monoclonal, although some cases were polyclonal. These suggest that invasive carcinoma of the cervix does not always arise from a single cell, but may arise from several cells with different mechanisms. 相似文献
22.
Jim-Shoung Lai T.-N. Wu Saou-Hsing Liou Chen-Yang Shen Chiam-Fang Guu Kquei-Nu Ko Chi. Hsueh-Yun P.-Y. Chang 《International archives of occupational and environmental health》1997,69(4):295-300
Objective: To examine the relationship between ambient lead levels and blood lead levels and to explore the modifiers of the relationship
between ambient lead and blood lead. Method: A cross-sectional study was conducted in two lead battery factories. Blood lead level and ambient lead concentration were
measured for each participant concurrently. A structured questionnaire was administered to collect sociodemographic characteristics
and occupational history. Design: Biological and personal environmental measurements of 219 lead-exposed workers were analyzed by both simple and multiple linear
regression. A regression model was selected for interpretation. Results: A high correlation (r=0.62) between ambient lead (PbA) and blood lead (PbB) was observed. In addition, numerous factors, including age, sex, alcohol
consumption, personal hygiene practice and type of lead exposure, were also found to influence blood lead levels. Although
PbB was highly correlated with PbA, blood lead level may not be effectively lowered by reducing ambient lead level. Based
on the regression coefficients, improvement of hygienic practice was more effective at lowering PbB than reducing ambient
lead level. Good hygienic practice may be the preferential way to reduce lead exposure in current conditions. Conclusion: Education of correct work practice may be more important than engineering control in the developing countries to lower blood
lead levels in lead battery factories.
Received: 28 May 1996/Accepted: 30 August 1996 相似文献
23.
Total respiratory resistance (Rrs) was measured by the application of a sine wave of airflow to the mouth at an oscillation frequency of 10 Hz. The instrument used was the Siemens Siregnost FD5. The Rrs data were correlated with height, age, sex, and weight in 73 patients and 29 healthy subjects. The patients took part in a rehabilitation program for restoration of their locomotion function. Both groups had normal lung function (VC, FEV1) and no signs of pulmonary disease. The only important determining factor for the value of the Rrs was height. The mean Rrs of 102 subjects was 0.29 +/- 0.08 kPa.1-1.s. Other studies gave values between 0.23 +/- 0.05 and 0.32 +/- 0.10 kPa.1-1.s. 相似文献
24.
OBJECTIVE: Hyperventilation and ischaemia increase axonal excitability by changing Na+ conductance in healthy subjects. However, the changes in excitability during and after ischaemia in diabetic patients are less than in healthy controls. This is known as ischaemic resistance. In this study, we investigated the effects of hyperventilation for 20 min on strength-duration time constant (SDTC) of motor axons of the median nerve of diabetic patients with polyneuropathy to determine whether diabetics are less affected by hyperventilation, a form of resistance similar to the ischaemic resistance of diabetics. METHODS: The SDTC of 14 diabetic patients with polyneuropathy and 10 healthy volunteers were measured following stimulation of right median nerve at the wrist prior to and after hyperventilation for 20 min. RESULTS: There was a significant increase in the SDTC in control subjects, but no significant change in the SDTC for patients with diabetic polyneuropathy. The score of the clinical response (paraesthesiae and carpopedal spasm) to hyperventilation of controls was also significantly greater in the controls than the patients. CONCLUSION: Hyperventilation for 20 min has little influence on SDTC in patients with diabetic polyneuropathy. SIGNIFICANCE: The 'resistance' of diabetic nerve is not confined to ischaemia but involves other manoeuvres that can alter axonal excitability. 相似文献
25.
Ethanol extract of Panax ginseng C. A. Meyer, which has been used for centuries as a tonic in Asian countries, exhibited a selective induction of epoxide hydratase and cytosolic glutathione transferase activity without the concurrent induction of aryl hydrocarbon hydroxylase activity. Thus, Panax ginseng appears to have the potential to alter the metabolic patterns of benzo(a)pyrene and its reactive metabolites. 相似文献
26.
27.
28.
J C Shih T L Ko M C Lin M K Shyu C N Lee F J Hsieh 《Ultrasound in obstetrics & gynecology》2004,24(2):202-206
The relationship of large and vascularized chorioangiomas to adverse pregnancy outcome is well recognized. We present a patient with a large placental tumor and signs of impending fetal cardiac failure. The angioarchitecture of the tumor depicted by three-dimensional (3D) power Doppler ultrasound enabled us to accurately diagnose a placental chorioangioma. During the follow-up period, quantitative flow data obtained using 3D power Doppler indicated altered hemodynamics in the tumor and concomitant improvement in the condition of the fetus, enabling us to manage the mother conservatively. Spontaneous delivery occurred at 38 weeks without any complications. This report demonstrates the potential value of 3D power Doppler in prenatal diagnosis and monitoring of pregnancies complicated by large, vascularized chorioangioma. 相似文献
29.
AIM: Benign childhood epilepsy with centro-temporal spikes (BCECTS) is the most common idiopathic partial epilepsy in children. Treatment attitudes remain a controversial issue. We examine features that could suggest refractoriness at onset. METHODS: We retrospectively reviewed the medical records of 144 children with BCECTS diagnosed at the Division of Pediatric Neurology, Asan Medical Center, from March 1, 1995, to April 30, 2002 and treated with AEDs. The patients were subdivided into two groups according to the number of antiepileptic drugs used for effective seizure control. RESULTS: Of the 144 patients, 75 were male and 69 were female, with a mean age at seizure-onset of 7.2 +/- 2.3 years (range, 2.1-14.3 years); 119 children were taking one antiepileptic drug (AED) (Group A), and 25 were taking more than one (Group B). There were no significant group differences in female-to-male ratio, prescribed AEDs, number of seizures before the start of treatment, interval between seizure-onset and start of treatment, presence of secondarily generalized seizures, or presence of bilateral EEG abnormalities. The groups differed however, in mean age at seizure onset (7.6 +/- 2.2 years versus 5.1 +/- 1.9 years, p < 0.05) and percentage of patients with seizure-onset before 3 years (p < 0.05). CONCLUSIONS: When treated with AEDs, children with BCECTS usually respond well. However, an earlier onset of seizures is associated with more frequent seizures and initial refractoriness to medical treatment. 相似文献
30.
S. Koëter C. J. M. van Loon J. L. C. van Susante 《European journal of orthopaedic surgery & traumatology : orthopedie traumatologie》2006,16(3):268-270
A lateral patella luxation is occasionally complicated by an (osteo)chondral fracture. These fractures are usually located at the inferomedial part of the patella. In this case report we describe an osteochondral fracture of the lateral femoral condyle after a dislocation of the patella. The latter is a more severe injury because it involves an important weight bearing part of the knee joint. Refixation of the osteochondral fracture should be pursued. Various surgical techniques using nonresorbable materials have been described. We describe the advantages and disadvantages of refixation with biodegradable pin fixation for an osteochondral fracture caused by a patellaluxation. 相似文献