全文获取类型
收费全文 | 18584篇 |
免费 | 1167篇 |
国内免费 | 93篇 |
专业分类
耳鼻咽喉 | 296篇 |
儿科学 | 342篇 |
妇产科学 | 359篇 |
基础医学 | 2776篇 |
口腔科学 | 1777篇 |
临床医学 | 1488篇 |
内科学 | 4010篇 |
皮肤病学 | 421篇 |
神经病学 | 1275篇 |
特种医学 | 328篇 |
外科学 | 2097篇 |
综合类 | 49篇 |
一般理论 | 9篇 |
预防医学 | 2060篇 |
眼科学 | 229篇 |
药学 | 1418篇 |
中国医学 | 220篇 |
肿瘤学 | 690篇 |
出版年
2023年 | 201篇 |
2022年 | 334篇 |
2021年 | 777篇 |
2020年 | 502篇 |
2019年 | 665篇 |
2018年 | 817篇 |
2017年 | 540篇 |
2016年 | 606篇 |
2015年 | 674篇 |
2014年 | 899篇 |
2013年 | 1076篇 |
2012年 | 1561篇 |
2011年 | 1789篇 |
2010年 | 899篇 |
2009年 | 688篇 |
2008年 | 1122篇 |
2007年 | 1079篇 |
2006年 | 933篇 |
2005年 | 814篇 |
2004年 | 659篇 |
2003年 | 567篇 |
2002年 | 546篇 |
2001年 | 300篇 |
2000年 | 298篇 |
1999年 | 235篇 |
1998年 | 71篇 |
1997年 | 60篇 |
1996年 | 37篇 |
1995年 | 47篇 |
1994年 | 50篇 |
1993年 | 41篇 |
1992年 | 120篇 |
1991年 | 81篇 |
1990年 | 77篇 |
1989年 | 73篇 |
1988年 | 51篇 |
1987年 | 42篇 |
1986年 | 44篇 |
1985年 | 41篇 |
1984年 | 33篇 |
1983年 | 20篇 |
1982年 | 22篇 |
1980年 | 23篇 |
1979年 | 20篇 |
1978年 | 26篇 |
1974年 | 18篇 |
1973年 | 25篇 |
1971年 | 23篇 |
1970年 | 20篇 |
1969年 | 25篇 |
排序方式: 共有10000条查询结果,搜索用时 578 毫秒
41.
J N dos Santos A M e Silva P Alexandrino T Saldanha M O Carrageta E Ferreira F de Pádua 《The Netherlands journal of medicine》1991,38(5-6):212-216
Inherited defects of the natural coagulation inhibitors predispose patients to thrombosis. These disorders have similar clinical presentations with a strong family history of thrombosis, episodes of recurrent venous thromboembolism, beginning in early adulthood. We report a case of upper gastrointestinal bleeding in a patient with portal hypertension due to portal-vein thrombosis secondary to hereditary protein C deficiency, an association that has seldom been reported. 相似文献
42.
43.
One of the main obstacles for the introduction of PCR method to identify HIV1 proviral DNA in routine diagnostic laboratories is the use of radiolabelled oligodeoxynucleotide probes. Nonradioactive labelled probes have several advantages over radioactive labelling: they are stable for over 1 year, they can be produced easily in large amounts and they are safe. Polymerase chain reaction is an efficient and simple method to produce vector free inserts to use as probes. In this paper we describe a procedure for labelling DNA probes with digoxigenin-11-dUTP using the polymerase chain reaction. This non-radioactive labelling system was applied to detect HIV proviral sequences, amplified in vitro by PCR, from peripheral blood mononuclear cells DNA of infected subjects. We found identical sensitivities and specificities for probes synthesized with the non-radioactive and radioactive labelling procedures. The digoxigenin-11-dUTP can be efficiently incorporated during amplification of a DNA fragment using the polymerase chain reaction. This labelling and detection method proved to be specific, sensible and simple enough to be used in routine diagnostic laboratories for the detection of HIV1 infected individuals. 相似文献
44.
Telma T Florêncio Haroldo S Ferreira Jairo C Cavalcante Gabriela R Stux Ana L Sawaya 《European journal of cardiovascular prevention and rehabilitation》2007,14(2):346-348
OBJECTIVE: To test the hypothesis that short stature is associated with abdominal obesity, insulin resistance and lipid profile changes. METHODS: Anthropometric data were collected from 237 women (18-60 years old), residents of a shantytown in Maceió. Biochemical profiles of 60 individuals drawn from this population were determined. RESULTS: Total and low-density lipoprotein (LDL) cholesterol levels and insulin resistance rose with increasing waist : hip circumference ratio, particularly in women. Short, overweight individuals exhibited larger biochemical alterations than overweight individuals of average stature. CONCLUSION: Short stature, when associated with overweight, is a risk factor for increased insulin resistance and alterations in lipid profile. 相似文献
45.
Barbara Porton Adriana Ferreira Lynn E DeLisi Hung Teh Kao 《Neuropsychopharmacology》2004,55(2):118-125
BACKGROUND: Synapsin III plays a role in neuronal plasticity and maps to chromosome 22q12-13, a region suggested to be linked to schizophrenia. To determine if synapsin III plays a role in this disease, we searched for polymorphisms in this gene in patients with schizophrenia and controls. METHODS: The synapsin III gene was initially sequenced from 10 individuals with schizophrenia to identify polymorphisms. Association analysis was then performed using 118 individuals with schizophrenia and 330 population controls. Synapsin III expression was studied by immunoblot analyses, and phosphorylation sites were mapped by sequencing trypsin-digested synapsin III fragments phosphorylated with phosphorus-32. RESULTS: A rare, missense polymorphism, S470N, was identified in the synapsin III gene and appeared more frequently in individuals with schizophrenia than in controls (p =.0048). The site affected by the polymorphism, Ser470, was determined to be a substrate for mitogen-activated protein kinase, a downstream effector of neurotrophin action. Phosphorylation at Ser470 was increased during neonatal development and in response to neurotrophin-3 in cultured hippocampal neurons. CONCLUSIONS: Our observations suggest an association of a rare polymorphism in synapsin III with schizophrenia, but further studies will be required to clarify its role in this disease. 相似文献
46.
47.
48.
49.
Rats were injected daily with isoproterenol (2 mg/kg of body wt) for up to five days, or their incisor teeth were amputated on every other day for up to five amputations. The animals were subdivided in two subgroups killed 12 or 24 h after the first or last intervention. At 12 h all enzymes except hexokinase (HK) and pyruvate kinase (PFK) showed decreased activities after isoproterenol. After incisor amputation, only increased HK and PFK activities were observed. With both procedures, there is activation of beta-adrenergic receptors but results show that different biochemical events take place, suggesting different mechanisms. 相似文献
50.
Lucia Carvalho Monica Lipay Francisco Belfort Ivan Santos Joyce Andrade Alessandra Haddad Flavia Brunstein Lydia Ferreira 《Journal of plastic, reconstructive & aesthetic surgery》2006,59(9):961-968
BACKGROUND: Telomerase activity (TA) is believed to play a role in the regulation of senescence and to limit the number of cell divisions. The deregulation of telomerase appears to contribute to oncogenesis and the formation of immortal cell lines. As a result, it is believed that it could be used as a prognostic marker in melanoma. METHODS: TA was assayed by the polymerase chain reaction PCR-ELISA-based telomeric repeat amplification protocol (TRAP assay). One hundred and eight samples were distributed in four histological groups: 30 samples from primary cutaneous melanomas, 24 from peritumoural skin sites, 28 from benign melanocytic lesions, and 26 from normal skin sites as a control. RESULTS: TA was different among the four tested groups (Kruskall-Wallis test p<0.001), and increasing values of TA were observed progressing from normal skin to benign and then to malignant lesions. Among melanoma samples, there was a significant association between TA and ulceration (p=0.025), TA and vascular invasion (p=0.018) and TA and mitotic rate (p=0.029) (Mann-Whitney test). A linear regression analysis showed significant associations between the increase of TA with Breslow thickness (p=0.004) and the presence of satellites (p=0.002). CONCLUSIONS: We observed that TA had increased from control skin to peritumoural skin, and then to benign melanocytic lesions and finally to melanoma, suggesting tumour progression. TA showed higher values in the presence of some important histopathologic parameters related to poor prognosis in cutaneous melanoma such as ulceration, vascular invasion, satellites, high rates of mitosis, and in thicker tumours. 相似文献