全文获取类型
收费全文 | 11141篇 |
免费 | 681篇 |
国内免费 | 102篇 |
专业分类
耳鼻咽喉 | 106篇 |
儿科学 | 221篇 |
妇产科学 | 309篇 |
基础医学 | 1428篇 |
口腔科学 | 445篇 |
临床医学 | 899篇 |
内科学 | 2771篇 |
皮肤病学 | 134篇 |
神经病学 | 948篇 |
特种医学 | 455篇 |
外科学 | 1881篇 |
综合类 | 34篇 |
预防医学 | 474篇 |
眼科学 | 119篇 |
药学 | 671篇 |
中国医学 | 31篇 |
肿瘤学 | 998篇 |
出版年
2024年 | 6篇 |
2023年 | 79篇 |
2022年 | 190篇 |
2021年 | 382篇 |
2020年 | 221篇 |
2019年 | 324篇 |
2018年 | 400篇 |
2017年 | 272篇 |
2016年 | 329篇 |
2015年 | 391篇 |
2014年 | 592篇 |
2013年 | 648篇 |
2012年 | 948篇 |
2011年 | 960篇 |
2010年 | 517篇 |
2009年 | 498篇 |
2008年 | 758篇 |
2007年 | 774篇 |
2006年 | 639篇 |
2005年 | 640篇 |
2004年 | 636篇 |
2003年 | 507篇 |
2002年 | 409篇 |
2001年 | 62篇 |
2000年 | 48篇 |
1999年 | 67篇 |
1998年 | 72篇 |
1997年 | 70篇 |
1996年 | 56篇 |
1995年 | 50篇 |
1994年 | 57篇 |
1993年 | 50篇 |
1992年 | 27篇 |
1991年 | 37篇 |
1990年 | 26篇 |
1989年 | 25篇 |
1988年 | 23篇 |
1987年 | 15篇 |
1986年 | 18篇 |
1985年 | 10篇 |
1984年 | 13篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1977年 | 5篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1973年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 453 毫秒
81.
82.
Coral-Vazquez RM Rosas-Vargas H Meza-Espinosa P Mendoza I Huicochea JC Ramon G Salamanca F 《Journal of human genetics》2003,48(2):91-95
The congenital muscular dystrophies (CMDs) are a heterogeneous group of autosomal recessive disorders. Approximately one half of cases diagnosed with classic CMD show primary deficiency of the laminin alpha2 chain of merosin. Complete absence of this protein is usually associated with a severe phenotype characterized by drastic muscle weakness and characteristic changes in white matter in cerebral magnetic resonance imaging (MRI). Here we report an 8-month-old Mexican female infant, from a consanguineous family, with classical CMD. Serum creatine kinase was elevated, muscle biopsy showed dystrophic changes, and there were abnormalities in brain MRI. Immunofluorescence analysis demonstrated the complete absence of laminin alpha2. In contrast, expression of alpha-, beta-, gamma-, and delta-sarcoglycans and dystrophin, all components of the dystrophin-glycoprotein complex, appeared normal. A homozygous C long right arrow T substitution at position 7781 that generated a stop codon in the G domain of the protein was identified by mutation analysis of the laminin alpha2 gene ( LAMA2). Sequence analysis on available DNA samples of the family showed that parents and other relatives were carriers of the mutation. 相似文献
83.
Rosenquist R Menestrina F Lestani M Küppers R Hansmann ML Bräuninger A 《Laboratory investigation; a journal of technical methods and pathology》2004,84(2):253-262
Composite lymphomas are rare combinations of Hodgkin's lymphoma (HL) and non-Hodgkin's lymphoma in the same patient, where clonal relatedness has been observed in most of the few cases analyzed. Here, we report a composite classical HL and diffuse large B-cell lymphoma (DLBCL) with interesting molecular features. Micromanipulation of single cells and analysis of V gene rearrangements revealed clonal relatedness with shared and distinct mutations, indicative of derivation from a common germinal center (GC) B-cell precursor and also of further development of both lymphomas in a GC. In the DLBCL, a very high mutation load, including inactivating mutations, and two copies of the same clonal rearrangement with different mutations in single cells were observed. Intriguingly, in the DLBCL precursor somatic hypermutation activity continued after acquisition of destructive V gene mutations, a feature previously found only in Epstein-Barr virus (EBV) infected B-cell expansions. Furthermore, we found evidence of light-chain receptor revision in the lymphoma precursor during a GC reaction. Re-expression of the V(D)J recombination machinery may enhance genomic instability in GC B cells and contribute to lymphomagenesis. 相似文献
84.
85.
86.
Vincenzo Arena Fabio De Giorgio Antonio Abbate Arnaldo Capelli Domenico De Mercurio Arnaldo Carbone 《Cardiovascular pathology》2004,13(4):230-232
We report a rare case of sudden death due to cardiac tamponade following intrapericardial rupture of a main pulmonary artery dissecting aneurysm. On pathology examination, the pulmonary artery showed an intimal tear in an arterial wall area with reduced thickness. However, no degenerative, inflammatory or necrotic processes were evident within the vessel wall. Hypertrophy of the wall of vasa vasorum in the adventitia of the pulmonary artery was found, as well as bilaterally diffuse myointimal arterial hyperplasia of the lung vasculature. According to these findings, we conclude that pulmonary artery rupture occurred in a patient with chronic unrecognized primary pulmonary hypertension. 相似文献
87.
Reduced Left Ventricular Compliance and Mechanical Efficiency after Prolonged Inhibition of NO Synthesis in Conscious Dogs 总被引:1,自引:0,他引:1
Heiner Post Chiara d'Agostino Vincenzo Lionetti Michele Castellari Elaine Y. Kang Martin Altarejos Xiaobin Xu Thomas H. Hintze Fabio A. Recchia 《The Journal of physiology》2003,552(1):233-239
Acute inhibition of NO synthesis decreases left ventricular (LV) work and external efficiency, but it is unknown whether compensatory mechanisms can limit the alterations in LV mechanoenergetics after prolonged NO deficiency. Eight chronically instrumented male mongrel dogs received 35 mg kg−1 day−1 of N ω -nitro-L-arginine methyl ester orally for 10 days to inhibit NO synthesis. At spontaneous beating frequency, heart rate, coronary blood flow, peak LV pressure, end-diastolic LV pressure and the maximum derivative of LV pressure (d P /d t max ) were not significantly different vs. baseline, whereas LV end-diastolic diameter (32.5 ± 1.0 vs. 37.6 ± 1.4 mm) and LV stroke work (515 ± 38 vs. 650 ± 44 mmHg mm), were reduced (all P < 0.05). The slope of the LV end-systolic pressure-diameter relationship was increased at 10 days vs. baseline (13.9 ± 1.0 vs. 9.6 ± 0.9 mmHg mm−1 , P < 0.05), while the end-diastolic LV diameter was smaller at matched LV end-diastolic pressures. At fixed heart rate (130 beats min−1 ), cardiac oxygen consumption was increased (12.2 ± 1.5 vs. 9.9 ± 1.0 ml min−1 ), and the ratio between stroke work and oxygen consumption was decreased by 33 ±7 % (all P < 0.05) after NO inhibition. We conclude that sustained inhibition of NO synthesis in dogs causes a decrease in LV work despite an increased contractility, which is most probably due to reduced diastolic compliance and a decrease in external efficiency. Thus, prolonged NO deficiency is not compensated for on the level of LV mechanoenergetics in vivo . 相似文献
88.
Matrix metalloproteinase-2, -9, and tissue inhibitor of metalloproteinase-1 in patients with hypertension. 总被引:6,自引:0,他引:6
Giuseppe Derosa Angela D'Angelo Leonardina Ciccarelli Mario N Piccinni Fabio Pricolo Sibilla Salvadeo Lorenza Montagna Alessia Gravina Ilaria Ferrari Simona Galli Sonia Paniga Carmine Tinelli Arrigo F G Cicero 《Endothelium》2006,13(3):227-231
There are conflicting data in the literature regarding the expression pattern of the vascular matrix metalloproteinase (MMP) system and their inhibitors (TIMPs) in human hypertension. The authors hypothesized that MMP-2, MMP-9, and TIMP-1 would be abnormal in hypertension, reflecting alterations in extracellular matrix (ECM) turnover. The authors measured plasma levels and activities of MMP-2, MMP-9, and TIMP-1 in 44 hypertensive patients and 44 controls. MMP-2 levels and activity were significantly higher in hypertensive group (p < .0001). Significant increase was also observed for MMP-9 level and activity (p < .0001) and for TIMP-1 (p < .0001) in hypertensive patients. Plasma levels and activities of MMP-2, MMP-9, and TIMP-1 are increased in hypertensive patients, which may reflect abnormal ECM metabolism. 相似文献
89.
Luis F Gonzalez-Cuyar Dora Lam-Himlin Fabio Tavora Allen Burke Rudy J Castellani 《Cardiovascular pathology》2008,17(2):113-116
BACKGROUND: Bilateral internal carotid artery agenesis (ICAA) is a rare developmental anomaly of unknown etiology that is often associated with disruption of adequate perfusion to the central nervous system. Nevertheless, some patients remain asymptomatic due to collateral circulation involving the communicating arteries of the Circle of Willis. Secondary to the hemodynamical stress through the collateral circulation, affected patients are at an increased risk of developing subarachnoid hemorrhage and intracranial aneurysms. METHODS AND RESULTS: We report an unusual case of a 62-year-old man with bilateral ICAA who expired following two asystolic events during minor surgery. CONCLUSION: This case emphasizes the plasticity of the cerebral collateral circulation during development, to the point of normal cerebral perfusion throughout life with no ischemic complications. 相似文献
90.
Ricciardolo FL Caramori G Ito K Capelli A Brun P Abatangelo G Papi A Chung KF Adcock I Barnes PJ Donner CF Rossi A Di Stefano A 《The Journal of allergy and clinical immunology》2005,116(5):1028-1035
BACKGROUND: Reactive nitrogen species, formed via the reaction of nitric oxide (NO) with superoxide anion and via (myelo)peroxidase-dependent oxidation of NO(2)(-), have potent proinflammatory and oxidizing actions. Reactive nitrogen species formation and nitrosative stress are potentially involved in chronic obstructive pulmonary disease (COPD) pathogenesis. OBJECTIVES: To investigate the expression of markers of nitrosative stress, including nitrotyrosine (NT), inducible NO synthase (iNOS), endothelial NO synthase (eNOS), myeloperoxidase (MPO), and xanthine oxidase (XO) in bronchial biopsies and bronchoalveolar lavage from patients with mild to severe stable COPD compared with control groups (smokers with normal lung function and nonsmokers). METHODS: The expression of NT, iNOS, eNOS, MPO and XO in the bronchial mucosa and bronchoalveolar lavage of patients was measured by using immunohistochemistry, Western blotting, and ELISA and correlated with the inflammatory cell profile. RESULTS: Patients with severe COPD in stable phase had higher numbers of NT(+) and MPO(+) cells in their bronchial submucosa compared with mild/moderate COPD, smokers with normal lung function, and nonsmokers (P < .01). iNOS(+) and eNOS(+) but not XO(+) cells were significantly increased in smokers with COPD or normal lung function compared with nonsmokers (P < .05 and P < .01, respectively). In patients with COPD, the number of MPO(+) cells was significantly correlated with the number of neutrophils (r = +0.61; P < .0025) in the bronchial submucosa. Furthermore, the number of NT(+) and MPO(+) cells was negatively correlated with postbronchodilator FEV(1). CONCLUSION: These data suggest that nitrosative stress, mainly mediated by MPO and neutrophilic inflammation, may contribute to the pathogenesis of severe COPD. 相似文献