全文获取类型
收费全文 | 1511篇 |
免费 | 79篇 |
国内免费 | 85篇 |
专业分类
耳鼻咽喉 | 1篇 |
儿科学 | 67篇 |
妇产科学 | 12篇 |
基础医学 | 146篇 |
口腔科学 | 23篇 |
临床医学 | 227篇 |
内科学 | 390篇 |
皮肤病学 | 33篇 |
神经病学 | 27篇 |
特种医学 | 302篇 |
外科学 | 171篇 |
综合类 | 33篇 |
预防医学 | 31篇 |
眼科学 | 6篇 |
药学 | 81篇 |
肿瘤学 | 125篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 13篇 |
2020年 | 2篇 |
2019年 | 12篇 |
2018年 | 11篇 |
2017年 | 11篇 |
2016年 | 13篇 |
2015年 | 18篇 |
2014年 | 12篇 |
2013年 | 30篇 |
2012年 | 14篇 |
2011年 | 24篇 |
2010年 | 52篇 |
2009年 | 54篇 |
2008年 | 32篇 |
2007年 | 69篇 |
2006年 | 28篇 |
2005年 | 43篇 |
2004年 | 29篇 |
2003年 | 28篇 |
2002年 | 44篇 |
2001年 | 30篇 |
2000年 | 31篇 |
1999年 | 39篇 |
1998年 | 99篇 |
1997年 | 96篇 |
1996年 | 114篇 |
1995年 | 85篇 |
1994年 | 88篇 |
1993年 | 77篇 |
1992年 | 34篇 |
1991年 | 44篇 |
1990年 | 40篇 |
1989年 | 40篇 |
1988年 | 45篇 |
1987年 | 37篇 |
1986年 | 42篇 |
1985年 | 39篇 |
1984年 | 16篇 |
1983年 | 25篇 |
1982年 | 20篇 |
1981年 | 21篇 |
1980年 | 17篇 |
1979年 | 4篇 |
1978年 | 9篇 |
1977年 | 14篇 |
1976年 | 13篇 |
1975年 | 7篇 |
1966年 | 1篇 |
排序方式: 共有1675条查询结果,搜索用时 375 毫秒
961.
Chronic pancreatitis can be a debilitating disease. Resection for complicated disease and in those patients with intractable pain is a major component of therapy. There are potentially important physiological advantages with the pylorus preserving Kausch-Whipple (P-KW) compared to the standard Kausch-Whipple (KW) resection but further prospective studies are required to show this unequivocally. The Beger's operation also represents a significant theoretical advance. Indeed it permits resection in a proportion in whom a PP-KW or KW would not be possible technically because of severe fibrosis around the intra-pancreatic portal venous system. Although we have adopted the Beger's operation on our unit, large comparative studies are required against the KW and PP-KW procedures to properly establish its value. The hidden malignancy is an important issue, which undermines the routine use of the Beger's operation. 相似文献
962.
Measurement of cytochrome P450 2A6 and 2E1 gene expression in primary human bronchial epithelial cells 总被引:3,自引:1,他引:3
Crawford EL; Weaver DA; DeMuth JP; Jackson CM; Khuder SA; Frampton MW; Utell MJ; Thilly WG; Willey JC 《Carcinogenesis》1998,19(10):1867-1871
Bronchogenic carcinomas arise from bronchial epithelial cells (BECs).
Inhalation exposure of BECs to nitrosamines in cigarette smoke is an
important exogenous risk factor for malignant transformation of BECs. Thus,
an important endogenous risk factor is likely to be the capacity of BECs to
metabolize nitrosamines. Among the cytochrome P450 enzymes capable of
metabolizing nitrosamines, CYP2A6, CYP2E1 and CYP2B6 are expressed in BECs.
In this study, we used quantitative RT-PCR to evaluate expression of CYP2A6
and CYP2E1 in primary human BECs from 12 non-smokers and eight smokers.
CYP2A6 was expressed in 20/20 cases and quantifiable in 18/20 cases, with a
mean level of 580 mRNA/10(6) beta- actin mRNA. CYP2E1 expression was
observed in 9/20 cases, but in all cases it was expressed at levels below
our limit of quantification (10 mRNA/10(6) beta-actin mRNA). There was
significant (P < 0.05) 20-fold inter-individual variation in expression
of CYP2A6. Further, the mean level of CYP2A6 among smokers (260 mRNA/10(6)
beta-actin mRNA) was significantly lower than among non-smokers (740
mRNA/10(6) beta-actin mRNA). It is hypothesized that: (i) inter-individual
variation in CYP2A6 gene expression may contribute to inter-individual
variation in risk for bronchogenic carcinoma; (ii) smoking may reduce the
level of expression of CYP2A6 in the BECs of some individuals; and (iii)
CYP2A6 is more important than CYP2E1 for metabolic activation of
nitrosamines in bronchial epithelial cells.
相似文献
963.
OBJECTIVES--Foot pathology is a major source of morbidity in adults with diabetes. The aim of this study was to determine if children with insulin dependent diabetes have an increased incidence of foot pathology compared with non-diabetic children. DESIGN--Questionnaire, clinical examination, and biomechanical assessment. SUBJECTS--67 diabetic children and a comparison group matched for age, sex, and social class. RESULTS--We found significantly more foot pathology in the children with diabetes (52 children) than the comparison group (28 children); with more biomechanical anomalies (58 children with diabetes, 34 comparison group); and a higher incidence of abnormal skin conditions (53 children with diabetes, 27 comparison group). Forty two children with diabetes had received foot health education compared with 27 in the comparison group, but the study revealed ignorance and misconceptions among the diabetic group, and previous contact with a podiatrist was minimal. CONCLUSIONS--The survey suggests that children with diabetes have an increased incidence of foot pathology justifying greater input of podiatric care in the hope of preventing later problems. 相似文献
964.
965.
966.
F Sardelic JP Fletcher D Ho K Simmons 《Journal of Medical Imaging and Radiation Oncology》1995,39(2):107-111
Pre-operative imaging of abdominal aortic aneurysms (AAA) is important in determining suitability for operation and operative approach. Ultrasound imaging is an excellent screening modality but is relatively poor at identifying renal arteries and the extent of iliac involvement. Computed tomography scanning with intravenous contrast and arteriography are invasive modalities that are associated with a small risk. Magnetic resonance imaging (MRI) offers the potential of accurate anatomical definition without use of contrast agents and passage of an intra-arterial catheter. Eight patients who had their AAA evaluated with MRI are reported. All had renal arteries accurately defined, intraaneurysmal thrombosis was well delineated, and iliac extension was correctly identified in four cases. The initial experience has been most encouraging and the authors consider that MRI may become the investigation of choice for pre-operative AAA assessment. 相似文献
967.
Biochemical prediction of gallstones in acute pancreatitis: a prospective study of three systems 总被引:2,自引:0,他引:2
B R Davidson J P Neoptolemos T Leese D L Carr-Locke 《The British journal of surgery》1988,75(3):213-215
Three clinicobiochemical systems have been proposed for predicting gallstones in acute pancreatitis based on one, three and five factors respectively, but have not been compared in a single prospective study. System 1 is based on the serum transaminase alone; system 2 uses alkaline phosphatase and bilirubin in addition to transaminase; and system 3 involves female gender, age, amylase and alkaline phosphatase in addition to transaminase. Over the 4-year period 1983-86, 368 patients with 391 episodes of acute pancreatitis had clinicobiochemical analysis within 48 h. Of these episodes, 220 were related to gallstones (56 per cent), 62 to alcohol (16 per cent) and 109 to other aetiologies or were idiopathic (28 per cent). Significant differences were found between the biliary and non-biliary groups with respect to sex (139 versus 59 women, P less than 0.002), age (65 +/- 17 versus 52 +/- 19 years, P less than 0.0001) and serum amylase (6041 +/- 6335 versus 4546 +/- 3990 units/l, P less than 0.0001), alkaline phosphatase (257 +/- 225 versus 141 +/- 137 units/l, P less than 0.0001), alanine transaminase (221 +/- 227 versus 72 +/- 119 units/l, P less than 0.0001) and bilirubin (40 +/- 39 versus 24 +/- 30 mumol/l, P = 0.0001). The sensitivity and specificity was 75 per cent and 74 per cent for the one-factor system, 74 per cent and 78 per cent for the three-factor system and 62 per cent and 80 per cent for the five-factor system. The predictive value of a positive result was 78.8 per cent, 81.5 per cent and 80.1 per cent and of a negative result 69.4 per cent, 70.1 per cent and 62.3 per cent for the three systems respectively. The performances of the one- and three-factor systems were marginally better than that of the five-factor system; the one-factor system, however, had the advantage of simplicity. 相似文献
968.
Indications for angiography in blunt thoracic trauma 总被引:1,自引:0,他引:1
The clinical charts and radiographs of 113 patients who underwent aortography for suspected blunt injury to the aorta and brachiocephalic vessels were reviewed to identify the most useful indications for angiography. Eight previously described clinical criteria and 14 previously described radiographic criteria were evaluated in each of these patients, 27 of whom had either an aortic or brachiocephalic injury. Contrary to previous reports, our data indicate that no single clinical or radiographic sign is highly specific for vascular injury. An abnormal aortic outline and mediastinal widening remain the most sensitive criteria, although these were also present in a large number of patients without vascular injury. Displaced paraspinous lines and nasogastric tubes are also useful signs. 相似文献
969.
Anti-RH immunoglobulin therapy for human immunodeficiency virus-related immune thrombocytopenic purpura 总被引:2,自引:0,他引:2
Oksenhendler E; Bierling P; Brossard Y; Schenmetzler C; Girard PM; Seligmann M; Clauvel JP 《Blood》1988,71(5):1499-1502
The potential hazards of steroids in human immunodeficiency virus (HIV)- infected patients led us to evaluate the effectiveness and safety of anti-D and anti-c Ig in 17 adults with severe HIV-related immune thrombocytopenic purpura (platelet count less than 20 x 10(9)/L). The 14 Rh+ patients received 12 to 25 micrograms/kg of anti-D IgG intravenously on two consecutive days. A significant platelet rise above 50 x 10(9)/L was obtained in nine patients. Repeated boosters were performed in six cases and were effective in all cases. The 3 Rh- patients had a good response after they were given 20 mL x 2 of plasma containing potent anti-c antibodies. Therapy was well tolerated, and only one patient had significant hemolysis. These data suggest that anti-Rh IgG can be effective and safe in HIV-related thrombocytopenic purpura and that a specific interaction between the RBC antigens and the anti-Rh antibodies is required. 相似文献
970.