全文获取类型
收费全文 | 429122篇 |
免费 | 32129篇 |
国内免费 | 17301篇 |
专业分类
耳鼻咽喉 | 4889篇 |
儿科学 | 13334篇 |
妇产科学 | 4830篇 |
基础医学 | 49168篇 |
口腔科学 | 9388篇 |
临床医学 | 43617篇 |
内科学 | 77272篇 |
皮肤病学 | 7292篇 |
神经病学 | 20464篇 |
特种医学 | 17824篇 |
外国民族医学 | 150篇 |
外科学 | 53595篇 |
综合类 | 53435篇 |
现状与发展 | 84篇 |
预防医学 | 21423篇 |
眼科学 | 7872篇 |
药学 | 40294篇 |
144篇 | |
中国医学 | 13448篇 |
肿瘤学 | 40029篇 |
出版年
2024年 | 928篇 |
2023年 | 5681篇 |
2022年 | 13730篇 |
2021年 | 17750篇 |
2020年 | 12520篇 |
2019年 | 17597篇 |
2018年 | 12657篇 |
2017年 | 12432篇 |
2016年 | 14901篇 |
2015年 | 18211篇 |
2014年 | 29771篇 |
2013年 | 28677篇 |
2012年 | 30031篇 |
2011年 | 28378篇 |
2010年 | 24789篇 |
2009年 | 24032篇 |
2008年 | 23161篇 |
2007年 | 23349篇 |
2006年 | 20652篇 |
2005年 | 16011篇 |
2004年 | 11432篇 |
2003年 | 9977篇 |
2002年 | 8225篇 |
2001年 | 7008篇 |
2000年 | 5929篇 |
1999年 | 4820篇 |
1998年 | 5050篇 |
1997年 | 4609篇 |
1996年 | 4023篇 |
1995年 | 3694篇 |
1994年 | 3409篇 |
1993年 | 2749篇 |
1992年 | 2681篇 |
1991年 | 2415篇 |
1990年 | 2187篇 |
1989年 | 2044篇 |
1988年 | 1914篇 |
1987年 | 1599篇 |
1986年 | 1396篇 |
1985年 | 2488篇 |
1984年 | 2513篇 |
1983年 | 1807篇 |
1982年 | 1935篇 |
1981年 | 1802篇 |
1980年 | 1557篇 |
1979年 | 1305篇 |
1978年 | 1009篇 |
1977年 | 952篇 |
1976年 | 838篇 |
1974年 | 509篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
ObjectiveThe beneficial effects of carnitine supplementation on nonalcoholic fatty liver disease are unclear. We conducted a systematic review and meta-analysis to evaluate the effects of carnitine supplementation on liver function, lipid profile, body mass index, body weight, and homeostasis model assessment of insulin resistance in patients with nonalcoholic fatty liver disease.MethodsA comprehensive search of PubMed, Web of Science, Scopus, Cochrane Library, and Google Scholar databases were performed. Only randomized placebo-controlled human studies that examined the effects of carnitine supplementation on liver function, lipid profile, body mass index, body weight, and homeostasis model assessment of insulin resistance up to September 2019 were included. Fixed effects or random-effects models were applied to compute the pooled effect size. Heterogeneity assessments were performed using Cochran’s Q test and I-squared statistics. The quality of the studies was assessed using the Jaded scale.ResultsA total of 5 articles were selected, including 334 individuals (167 in control and 167 in intervention groups). The results demonstrated that carnitine supplementation significantly reduced homeostasis model assessment of insulin resistance (HOMA-IR) (WMD: −0.91; 95 % CI: −1.11, −0.72; p < 0.001, I2 = 0.0 %) and the levels of aspartate aminotransferase (AST) (WMD: −16.62; 95 % CI: −28.11, −5.14; IU/l; p = 0.005, I2 = 93.5 %), alanine aminotransferase (ALT) (WMD: -33.39; 95 % CI: −45.13, −21.66; IU/l; p < 0.001, I2 = 93.4 %), and triglycerides (TG) (WMD: −22.13; 95 % CI: −38.91, −5.34; mg/dl; p = 0.01; I2 = 0.0 %). However, the results of the pooled effect size did not show any significant effect of carnitine supplementation on body mass index (BMI) (WMD: 0.07; 95 % CI: −0.15, 0.29; p = 0.55; I2 = 0.0 %), body weight (WMD: −0.28; 95 % CI: −2.23, 1.68; p = 0.78; I2 = 45.7 %), the levels of gamma-glutamyl transferase (γGT) (WMD: −11.31; 95 % CI: −24.35, 1.73; IU/l; p = 0.09, I2 = 61.1 %), cholesterol (WMD: −13.58; 95 % CI: −46.77, 19.60; mg/dl; p = 0.42; I2 = 94.9 %), high-density lipoprotein-cholesterol (HDL-C) (WMD: 1.36; 95 % CI: −0.96, 3.68; mg/dl; p = 0.25; I2 = 64.7 %), and low density lipoprotein-cholesterol (LDL-C) (WMD: −14.85; 95 % CI: −45.43, 15.73; mg/dl; p = 0.34; I2 = 96.4 %).ConclusionsThis analysis shows that carnitine supplementation for patients with nonalcoholic fatty liver disease demonstrates a reduction in AST, ALT, TG levels and HOMA-IR. However, no significant effect of carnitine supplementation was observed on BMI, body weight, the levels of γGT, TC, HDL-cholesterol and LDL-cholesterol. 相似文献
182.
183.
184.
185.
186.
《Neuro-Chirurgie》2022,68(2):196-201
BackgroundTumor-to-tumor metastases are extremely rarely reported lesions, which usually involve an indolent lesion hosting a more aggressive neoplasm. We present an unusual initial manifestation of a previously unknown clear cell renal cell carcinoma as a tumor-to-tumor metastasis in a typical meningothelial meningioma.Case reportA 73-year old patient with transient left slight monoparesis was addressed to our Neurosurgical Department after being evaluated by his general practitioner and passing a cerebral MRI which revealed a right frontotemporal mass attached to the meninge. At presentation, no deficits were identified; therefore an elective surgery was proposed. Histological analysis revealed a typical meningothelial meningioma containing a metastatic clear cell renal cell carcinoma. Additional thoraco-abdominal computer tomography identified a 6 cm diameter lesion within the right kidney with radiological features highly suggestive of a primary clear cell renal cell carcinoma.ConclusionOur case highlights the need for a specialized neuropathological approach to clinical and imagistic indolent meningiomas, as they may require important differential diagnosis that can highly impact the treatment and follow-up of brain tumor patients. 相似文献
187.
Nirmanmoh Bhatia Buddhadeb Dawn Tariq S. Siddiqui Marcus F. Stoddard 《Texas Heart Institute journal / from the Texas Heart Institute of St. Luke's Episcopal Hospital, Texas Children's Hospital》2015,42(1):16-24
Determining aortic stenosis (AS) severity is clinically important. Calculating aortic valve (AV) area by means of the continuity equation assumes a circular left ventricular outflow tract (LVOT). The full impact of this assumption in calculating AV area is unknown. Predictors of noncircular LVOT shape in patients with AS are undefined.In 109 adult patients with AS who underwent multiplanar transesophageal echocardiography, we calculated AV area by means of the standard continuity method and by a modified method involving planimetric LVOT area.We found 54 circular, 37 horizontal-oval, 8 vertical-oval, and 10 irregular LVOTs. Area derived by direct planimetry correlated better with the modified than the standard continuity method (r=0.89 vs r=0.85; both P=0.0001). Valve areas of patients with mild, moderate, or severe AS by planimetry were more often mischaracterized with use of the standard than modified method (29 vs 18; P <0.0001). Horizontal-oval AV area derived by planimetry (1.28 ± 0.55 cm2) was underestimated by the standard method (1.05 ± 0.47 cm2; P=0.001), but not by the modified method. Congenital AV morphology and low cardiac index were the only multivariate predictors of horizontal-oval shape. Low cardiac index was the only predictor of noncircular shape.More than half our patients with AS had noncircular LVOTs. Using the modified method reduces mischaracterizations of AS severity. Congenital AV morphology and low cardiac index predict horizontal-oval or noncircular shape. These data suggest the value of direct LVOT measurement to calculate AS severity in patients who have congenital AV or a low cardiac index. 相似文献
188.
I Ahmad 《Annals of the Royal College of Surgeons of England》2015,97(7):481-486
Urothelial cell carcinoma (UCC) of the bladder is one of the most common malignancies, causing considerable morbidity and mortality worldwide. It is unique among the epithelial carcinomas as two distinct pathways to tumourigenesis appear to exist: low grade, recurring papillary tumours usually contain oncogenic mutations in FGFR3 or HRAS whereas high grade, muscle invasive tumours with metastatic potential generally have defects in the pathways controlled by the tumour suppressors p53 and retinoblastoma. Over the last two decades, a number of transgenic mouse models of UCC, containing deletions or mutations of key tumour suppressor genes or oncogenes, have helped us understand the mechanisms behind tumour development. In this summary, I present my work investigating the role of the WNT signalling cascade in UCC. 相似文献
189.
190.