全文获取类型
收费全文 | 3681篇 |
免费 | 159篇 |
国内免费 | 10篇 |
专业分类
耳鼻咽喉 | 26篇 |
儿科学 | 125篇 |
妇产科学 | 42篇 |
基础医学 | 495篇 |
口腔科学 | 463篇 |
临床医学 | 256篇 |
内科学 | 696篇 |
皮肤病学 | 75篇 |
神经病学 | 174篇 |
特种医学 | 300篇 |
外科学 | 276篇 |
综合类 | 16篇 |
预防医学 | 351篇 |
眼科学 | 138篇 |
药学 | 271篇 |
中国医学 | 36篇 |
肿瘤学 | 110篇 |
出版年
2023年 | 27篇 |
2022年 | 71篇 |
2021年 | 99篇 |
2020年 | 68篇 |
2019年 | 87篇 |
2018年 | 114篇 |
2017年 | 66篇 |
2016年 | 71篇 |
2015年 | 93篇 |
2014年 | 144篇 |
2013年 | 176篇 |
2012年 | 260篇 |
2011年 | 306篇 |
2010年 | 151篇 |
2009年 | 143篇 |
2008年 | 204篇 |
2007年 | 191篇 |
2006年 | 149篇 |
2005年 | 128篇 |
2004年 | 112篇 |
2003年 | 98篇 |
2002年 | 73篇 |
2001年 | 57篇 |
2000年 | 58篇 |
1999年 | 44篇 |
1998年 | 60篇 |
1997年 | 74篇 |
1996年 | 55篇 |
1995年 | 47篇 |
1994年 | 61篇 |
1993年 | 56篇 |
1992年 | 31篇 |
1991年 | 30篇 |
1990年 | 19篇 |
1989年 | 43篇 |
1988年 | 51篇 |
1987年 | 29篇 |
1986年 | 36篇 |
1985年 | 35篇 |
1984年 | 22篇 |
1983年 | 28篇 |
1982年 | 18篇 |
1981年 | 22篇 |
1980年 | 23篇 |
1978年 | 11篇 |
1977年 | 19篇 |
1976年 | 13篇 |
1975年 | 20篇 |
1969年 | 6篇 |
1968年 | 11篇 |
排序方式: 共有3850条查询结果,搜索用时 15 毫秒
1.
2.
Maria C. Chammas Andre C. Oliveira Mario J. D´Ávilla Pedro H. Moraes Marcelo Straus Takahashi 《Ultrasound in medicine & biology》2019,45(1):50-55
We prospectively evaluated the effectiveness of contrast-enhanced ultrasonography (CEUS) for differentiation of benign versus malignant portal vein thrombosis (PVT). We studied a total of 43 patients with chronic liver disease, hepatocellular carcinoma-suggestive nodules and confirmed PVT, in whom the nature of the PVT was confirmed by follow-up imaging (US, computed tomography and/or magnetic resonance imaging) performed up to 6 mo after CEUS. PVT was assessed by US, Doppler US and CEUS with respect to vessel wall disruption and/or invasion, color Doppler vascularization, pulsed Doppler vascularization pattern and CEUS enhancement and vascularization pattern, and thrombi were classified as benign or malignant based on these findings. Follow-up studies revealed malignant PVT in 22 of the 43 patients (51%) and benign PVT in 21 patients (49%). CEUS findings were consistent with follow-up studies in 41 of the 43 patients (95%), with κ?=?0.903 (p < 0.0001), sensitivity?=?91% and specificity?=?100%, indicating that CEUS can be confidently used to differentiate benign from malignant portal vein thrombosis in the setting of chronic liver disease. 相似文献
3.
4.
S Dimauro C T Moraes S Shanske A Lombes H Nakase S Mita H J Tritschler E Bonilla A F Miranda E A Schon 《Revue neurologique》1991,147(6-7):443-449
Thanks to recent advances in the molecular genetics of mitochondrial encephalomyopathies, we can now begin to correlate genetic lesions with biochemical defects. In the fatal infantile myopathy due to cytochrome c oxidase (COX) deficiency, an autosomal recessive condition, immunocytochemical studies have shown an isolated defect of subunit VIIa, which is 1 of the only 2 tissue-specific subunits of human COX. In muscle biopsies from patients with Kearns-Sayre syndrome, a multisystem disorder characterized by deletions of the mitochondrial DNA (mtDNA), the activities of all mitochondrial enzymes containing mtDNA-encoded subunits are decreased. The results of Northern analysis, in situ hybridization, and immunocytochemistry in muscle, and of mitochondrial protein synthesis in cultured fibroblasts suggest that partially deleted mtDNAs are transcribed but not translated, probably due to lack of indispensable tRNAs. 相似文献
5.
Manifestations of insulin-dependent diabetes mellitus in the periodontium of young Brazilian patients 总被引:1,自引:0,他引:1
The periodontal condition of patients with insulin-dependent diabetes mellitus was evaluated in terms of plaque, gingival indices, pocket depth, and alveolar bone loss. Thirty male and female diabetic patients aged 5 to 18 years were compared with 30 non-diabetic subjects and correlated with sex and age. Statistical analyses of the data showed that the mean plaque index was significantly higher (P less than 0.01) among the diabetic patients (1.23) than among the control subjects (0.81). The plaque index was significantly higher (P less than 0.01) among diabetic females (1.34) than among diabetic males (1.10), whereas no sex differences were observed in the control group. The arithmetic means obtained for gingival index were statistically higher (P less than 0.01) for the diabetics (0.58) when compared with the controls (0.15), but no significant differences were obtained when the values were correlated with sex and age. Pocket depth did not differ statistically between groups. When pocket depth was correlated with sex, a statistically significant difference (P less than 0.05) was observed only for the palatal region, with a depth of 2.1 mm in female patients and 1.92 mm in male patients. When pocket depth was correlated with age, a positive correlation (P less than 0.01) was detected in the diabetic group for all regions investigated, whereas the correlation was not significant in the control group. Mean alveolar bone loss was higher in the anterior upper (1.94 mm) and anterior lower (1.87 mm) regions of the diabetic group when compared to the controls (1.52 and 1.37 mm respectively), the difference being significant at the 5% level of probability.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
6.
Mitochondrial myopathy of childhood associated with depletion of mitochondrial DNA. 总被引:12,自引:0,他引:12
H J Tritschler F Andreetta C T Moraes E Bonilla E Arnaudo M J Danon S Glass B M Zelaya E Vamos N Telerman-Toppet 《Neurology》1992,42(1):209-217
We have studied five children with mitochondrial myopathy manifesting within or soon after the first year of life. Muscle biopsies showed ragged-red fibers and decreased respiratory chain activity. All five patients had a severe decrease (2 to 34% of normal) in the amount of muscle mitochondrial DNA (mtDNA). The depletion of mtDNA correlated with absence of mtDNA-encoded translation products and with loss of cytochrome c oxidase enzyme activity in individual muscle fibers. This mitochondrial myopathy of childhood illustrates one phenotypic expression of a novel pathogenetic mechanism in mitochondrial diseases, the specific depletion of mtDNA in affected tissues. 相似文献
7.
8.
Hodgkin disease: CT of the thymus 总被引:2,自引:0,他引:2
The computed tomography (CT) scans in two groups of patients with Hodgkin disease were reviewed to determine the frequency of thymic enlargement. In 50 CT scans from 50 patients with evidence of thoracic disease on CT scans who were examined for primary staging, the thymus was enlarged in 15 of 50 (30%). Fifty CT scans were obtained from 44 patients at the time of 50 separate episodes of known or suspected relapse. Relapse occurred in the mediastinum in 12 episodes, lung parenchyma in five, and both sites in one. Thymic enlargement thought to be due to involvement by disease was present in seven of 18 (38%). Mediastinal disease was associated with thymic enlargement in all but one patient in whom a thymic cyst developed after radiation therapy. Differentiation of thymic enlargement from enlarged superior mediastinal lymph nodes was easily made in all but two patients. Thymic enlargement in the absence of lymph node enlargement may indicate a different disease, since isolated Hodgkin disease of the thymus is uncommon. Primary thymic tumor should be considered initially, whereas after treatment, rebound hyperplasia of the thymus may be the cause of enlargement. 相似文献
9.
Ulisses Xavier da Silva Neto Ivaldo Gomes de Moraes Vania Portela Ditzel Westphalen Renato Menezes Everdan Carneiro Luiz Fernando Fariniuk 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2007,104(2):e53-e57
OBJECTIVE: The aim of this study was to measure leakage of 4 resin-based sealers. STUDY DESIGN: Four groups of premolars (n = 60) were prepared using GT Rotary files and the crown-down technique and filled by the single-cone technique with AH26, AHPlus, EndoREZ, and an experimental MBP as sealer. Leakage was measured using the fluid filtration method after 15, 30, and 60 days and determined as microL/min(-1) x 10 psi. RESULTS: Statistical analysis by ANOVA and Tukey HSD test indicated that root fillings with AH Plus and the MBP showed lower leakage values after 15 days (P < .05). At 30 days, AH26 presented higher leakage values when compared to other sealers (P < .05). At 60 days, MBP and AH Plus presented the lower leakage values, differing significantly from EndoREZ (P < .05). CONCLUSION: It was observed that AH Plus and the experimental MBP showed lower leakage after 60 days than AH 26 and EndoREZ. 相似文献
10.
Maria Fernanda Nince Ferreira Verônica Moraes Oliveira Priscila Vieira da Cunha Osmindo Rodrigues Pires Júnior 《Toxicon》2010,55(7):1255-1262
This study evaluated the effects of [D-Leu1]Microcystin-LR variants, by the exposure of Hypophthalmichthys molitrix to Microcystis aeruginosa NPLJ4. Fish was placed in aquariums and exposed to 105 cells mL−1. For 15 days, 05 individuals were removed every 05 days, and tissue samples of liver, skeletal muscle and intestinal tract were collected for histopathologic analyses. Following exposure, those surviving were placed in clean water for 15 days to evaluate their recovery. A control without toxins was maintained in the same conditions and exhibited normal histology and no tissue damage. In exposed fish, samples were characterized by serious damages that similarly affected the different organs, such as dissociation of cells, necrosis and haemorrhage. Samples showed signs of recovery but severe damages were still observed. The results should be valuable to analyze the potency of microcystin toxicity and to help in the diagnosis of fish deaths. 相似文献