全文获取类型
收费全文 | 9425篇 |
免费 | 480篇 |
国内免费 | 99篇 |
专业分类
耳鼻咽喉 | 96篇 |
儿科学 | 183篇 |
妇产科学 | 171篇 |
基础医学 | 1105篇 |
口腔科学 | 231篇 |
临床医学 | 809篇 |
内科学 | 2689篇 |
皮肤病学 | 164篇 |
神经病学 | 1044篇 |
特种医学 | 283篇 |
外科学 | 1183篇 |
综合类 | 28篇 |
预防医学 | 436篇 |
眼科学 | 111篇 |
药学 | 571篇 |
中国医学 | 43篇 |
肿瘤学 | 857篇 |
出版年
2023年 | 64篇 |
2022年 | 133篇 |
2021年 | 284篇 |
2020年 | 165篇 |
2019年 | 205篇 |
2018年 | 265篇 |
2017年 | 181篇 |
2016年 | 247篇 |
2015年 | 297篇 |
2014年 | 335篇 |
2013年 | 520篇 |
2012年 | 789篇 |
2011年 | 685篇 |
2010年 | 427篇 |
2009年 | 401篇 |
2008年 | 618篇 |
2007年 | 666篇 |
2006年 | 585篇 |
2005年 | 634篇 |
2004年 | 546篇 |
2003年 | 453篇 |
2002年 | 441篇 |
2001年 | 68篇 |
2000年 | 62篇 |
1999年 | 58篇 |
1998年 | 79篇 |
1997年 | 77篇 |
1996年 | 43篇 |
1995年 | 55篇 |
1994年 | 45篇 |
1993年 | 37篇 |
1992年 | 35篇 |
1991年 | 42篇 |
1990年 | 36篇 |
1989年 | 30篇 |
1988年 | 39篇 |
1987年 | 32篇 |
1986年 | 29篇 |
1985年 | 33篇 |
1984年 | 29篇 |
1983年 | 21篇 |
1982年 | 20篇 |
1981年 | 25篇 |
1980年 | 35篇 |
1979年 | 14篇 |
1978年 | 10篇 |
1977年 | 12篇 |
1976年 | 12篇 |
1975年 | 12篇 |
1974年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 484 毫秒
71.
Soluble Antiapoptotic Molecules and Immune Activation in Chronic Heart Failure and Unstable Angina Pectoris 总被引:7,自引:0,他引:7
Fiorina P Astorri E Albertini R Secchi A Mello A Lanfredini M Craveri A Olivetti G Quaini F 《Journal of clinical immunology》2000,20(2):101-106
Programmed myocyte cell death and activation of the immune system have been shown to occur in patients with congestive heart failure. Besides, unstable angina episodes are likely to be associated with immune activation. Our aim was to evaluate the role of changes in circulating levels of soluble Fas (sFas), suggestive of an enhanced inhibitory response to ongoing apoptosis, and soluble IL2 receptor (sIL2-R), indicative of T-lymphocyte activation, in chronic heart failure and unstable angina pectoris. Thirty patients affected by chronic heart failure (20 idiopathic and 10 ischemic cardiomyopathy) and 13 patients with unstable angina were evaluated. Twenty healthy individuals matched for age and gender were used as controls. A complete biochemical determination of indexes of myocardial damage including cardiac troponin I (cTnI) and creatine kinase (MB/CK) was performed. The results demonstrated that mean levels of sFas and sIL2-R were significantly increased in patients affected by chronic heart failure and unstable angina and were not associated with changes in renal function or with serum levels of cTnI. Highest values of sFas were found in NYHA class IV patients (IV NYHA class = 7.39 ± 0.52 vs. controls = 1.34 ± 0.12 ng/ml; P < 0.01) and more elevated in idiopathic than in ischemic cardiomyopathy (3.64 ± 0.40 vs. 1.82 ± 0.37 ng/ml; P < 0.01). Moreover, in chronic heart failure patients sFas and ejection fraction were negatively correlated (P = 0.01), whereas sFas and sIL2-R were positively correlated (P < 0.01). In unstable angina patients too, sFas and sIL2-R appeared to be correlated (P = 0.03); whereas sFas (angina group = 3.18 ± 0.39 vs. controls = 1.34 ± 0.12 ng/ml; P < 0.01) and sIL2-R (angina group = 0.46 ± 0.11 vs. controls = 0.00 UI/ml; P < 0.01) were higher in angina group than in controls. In most of the cases, the increase of sFas was associated with comparable changes in sIL2-R serum levels, indicating that the activation of Fas system is strictly associated with autoimmune–inflammatory reactions. This phenomenon, both in chronic heart failure and in unstable angina, occurs in the absence of biochemical evidences of myocardial damage and seems to parallel the activation of T cell. Soluble Fas could have a role in sustaining inflammatory response and in prolonging the detrimental effects correlated with it in chronic heart failure and angina pectoris. 相似文献
72.
Gianluca Tkccagni Giacomo Dell'antonio Maria Rosa Terreni Angelo Cantaboni 《Ultrastructural pathology》1990,14(1):65-80
We performed an electron microscopic study of cytologic material from 20 cases of primary lung adenocarcinoma (pleural effusion, 13 cases; fine needle aspiration biopsy, 7 cases). Ultrastructural characteristics related to secretory and storing activity of adenocarcinoma cells were evaluated semi-quantitatively. Data analysis identified three basic cell types (secretory, well or poorly differentiated; storing; and indifferent). We could classify our cases in five groups of pure or mixed cytotypes. Our results demonstrated a subcellular morphological heterogeneity manifested by the presence of different basic cell types: secretory, storing or indifferent features (or both); and different secretory and storage products in the same cell. This heterogeneity of lung adenocarcinoma cells suggests that the neoplasm could arise from a single cell type capable of differentiating along different lines. Cases lacking secretory differentiation seemed to be characterized by more aggressive biologic behavior. A clear correlation between the ultrastructural cytotypes identified and the clinical and prognostic data on the patients was not observed. This may be due to the fact that 75% of the patients were in clinical stage III at the time of diagnosis; also, in this series only five cases did not have characteristics that indicated secretory activity. 相似文献
73.
Wayne C. Waltzer Radoslav J. Bachvaroff Angelo Arnold David Anaise Felix T. Rapaport 《Journal of clinical immunology》1985,5(2):78-83
The role and activity of natural killer (NK) cells following renal transplantation remain unknown. To monitor NK activity, a51Cr release of K-562 targets in prednisone-and azathioprine-treated patients receiving renal allografts was utilized. In 18 patients in whom NK activity was measured prior to and after transplantation, a significant diminution in NK activity within 3 weeks following transplantation was demonstrated compared to pretransplant values (34.71 vs 12.20%, respectively;P<0.001). In 11 subjects who had NK activity assayed at various intervals after transplantation but not prior to allografting, mean NK values were markedly lower (mean, 14.2%) than those of normal volunteers or patients maintained on hemodialysis (P<0.001). The latter two control groups demonstrated no difference (P = NS) in mean NK activity (39.46 vs 35.82%, respectively). In 5 of the 29 patients evaluated with good long-term graft function (mean, 2.7 years), restitution of normal NK activity was demonstrated. In two patients with bacterial infections, NK activity increased from 39.29 to 51.7% and from 13.54 to 20.00%. After infection, these values were 35.3% in the former and 3.39% in the latter. Viral infection did not appear to affect NK activity significantly. NK activity was increased in only one of seven patients with documented rejection episodes. In three of such patients, NK activity declined significantly following pulse methylprednisolone therapy. These results indicate that (1) NK-cell activity significantly decreases immediately after transplantation, probably as a result of immunosuppressive therapy; (2) NK activity does not appear to be stimulated by the alloreactive rejection process; (3) NK activity may be augmented in the course of bacterial but not viral infections; and (4) long-term allograft survival may be associated with a restoration of NK-cell levels in certain recipients. 相似文献
74.
Angelo B.M. Cunha Benicio N. Frey Ana C. Andreazza Júlia D. Goi Adriane R. Rosa Carlos A. Gonçalves Aida Santin Flavio Kapczinski 《Neuroscience letters》2006
Genetic and pharmacological studies have suggested that brain-derived neurotrophic factor (BDNF) may be associated with the pathophysiology of bipolar disorder (BD). The present study investigated serum BDNF levels in manic, depressed, euthymic BD patients and in matched healthy controls, using an enzyme-linked immunosorbent assay (sandwich-ELISA). Serum BDNF levels were decreased in manic (p = 0.019) and depressed (p = 0.027) BD patients, as compared with euthymic patients and controls. Serum BDNF levels were negatively correlated with the severity of manic (r = −0.37, p = 0.005) and depressive (r = −0.30, p = 0.033) symptoms. These findings further support the hypothesis that the BDNF signaling system may play a role in the pathophysiology of BD. 相似文献
75.
Lack of association between angiotensin converting enzyme polymorphism and sporadic Alzheimer's disease 总被引:3,自引:0,他引:3
Monastero R Caldarella R Mannino M Cefalù AB Lopez G Noto D Camarda C Camarda LK Notarbartolo A Averna MR Camarda R 《Neuroscience letters》2002,335(2):147-149
Epidemiological and pathogenetic evidences suggest a strong association between vascular risk factors and sporadic Alzheimer's disease (sAD). In agreement with the vascular hypothesis of AD, the role of various candidate genes for atherosclerosis has been investigated, leading to conflicting results. In order to clarify the significance of angiotensin-converting enzyme (ACE) gene insertion (I)/deletion (D) polymorphism in a group of patients with sAD, we conducted a case-control study including 149 cases and 149 age and sex matched controls. All subjects were genotyped for ACE and Apolipoprotein E (APOE). There were no significant differences in ACE genotype or allele frequencies between cases and controls, even after stratification for APOE4 carrier status. Our data suggest that the ACE I/D polymorphism is not associated to genetic susceptibility in sAD patients. 相似文献
76.
Analysis of 4-nitroquinoline-1-oxide induced mutations at the hprt locus in mammalian cells: possible involvement of preferential DNA repair 总被引:1,自引:0,他引:1
Inga Alberto; Iannone Raffaella; Degan Paolo; Campomenosi Paola; Fronza Gilberto; Abbondandolo Angelo; Menichini Paola 《Mutagenesis》1994,9(1):67-72
Mutation spectra induced by 4-nitroquinoline 1-oxide (4NQO)at the hprt locus for both normal (AA8) and 4NQO-sensitive (UV5)Chinese hamster ovary cells were determined to investigate theeffect of DNA repair on the nature of induced mutations. TheUV5 cell line is three times more sensitive to 4NQO than theAA8 parental cell line. In UV5 cells, the dGuo-N2-AQO adduct,which is considered to be the most toxic and mutagenic adductin Escherichia coli, is poorly repaired. The molecular natureof 30hprt mutants isolated from AA8 and 20 isolated from UV5cells was determined by sequence analysis of in vitro amplifiedhprtcDNA. Both similarities and differences emerged. In bothcell lines we found that (i) 4NQO is basically a base substitutionmutagen acting almost exclusively at G residues and (ii) G transversionsare prevalent over G transitions in both cell lines, independentlyfrom the ability to repair dGuo-N2-AQO. A high proportion (13/25)of splice mutations was observed in AA8 cells, statisticallydifferent (P < 0.04, Fishers exact test) from theincidence of splice mutants in UV5 cells (4/20). In AA8 mutants,all but two of the point mutations were due to lesions localizedon the non-transcribed strand, suggesting preferential repairof the transcribed strand. Compared with AA8, the proportionof mutants due to lesions present on the transcribed strandwas higher in UV5 cells, as expected if a preferential repairmechanism was impaired in the sensitive cell line. Our dataare consistent with the molecular defect in DNA repair recentlycharacterized in UV5.
3To whom correspondence should be addressed 相似文献
77.
Paradiso A Abatangelo M Piepoli S Tommasi S Xu JM Caponio MA Marzullo F D'Auria C Achille G Grammatica L 《Cancer Genetics and Cytogenetics》2002,132(2):141-144
Oncogene alterations have been clearly demonstrated to be related to the carcinogenesis and progression of oral squamous cell carcinoma (OSCC). However, the analysis of these alterations for screening and early diagnostic purposes generally requires invasive techniques for surgical removal of pathological epithelium. The aim of the present study was to assess the feasibility of fluorescence in situ hybridization (FISH) analysis of HER-2/neu amplification in oral mucosa brushings and to compare the HER-2/neu status with the history and smoking and drinking habits of healthy subjects. Cells obtained by centrifugation of oral brushings from 21 subjects (overall no. of cells: 5125) were suspended in physiological saline and fixed onto two slides for cytological evaluation and FISH analysis (dual-target, dual-color fluorescence assay) of the HER-2/neu gene and CEP17 centromere. A mean of 89.8% of the cells showed two HER-2/neu signals and a mean of 94% had two CEP17 signals at fluorescent microscopy. Finally, a mean of 96% of cells with HER-2/neu / CEP17 had a ratio equal to 1. No association between smoking and drinking habits, age and the HER-2/neu and CEP17 characteristics evaluated by FISH was found. 相似文献
78.
E Edalucci R Spinelli L Dolzani M Letizia Riccio V Dubois E Angelo Tonin G M Rossolini C Lagatolla 《Clinical microbiology and infection》2008,14(1):88-90
Multidrug-resistant isolates of a clonal lineage of Pseudomonas aeruginosa producing the VIM-2 metallo-beta-lactamase (MBL), involved in a large outbreak in an Italian hospital, were compared with MBL-negative strains that had caused outbreaks in two French hospitals. Although the isolates had different carbapenem MICs, the VIM-2-producing isolates from Italy carried identical, or very similar, allelic forms of the oprD gene, harboured a common class 1 integron, belonged to the same multilocus sequence type (ST111), and showed macrorestriction profiles that were related to those of the MBL-negative French strains. These results support the concept of independent acquisition of resistance determinants by members of a widespread clonal lineage of P. aeruginosa. 相似文献
79.
Scanu AM 《The New England journal of medicine》2003,349(22):2089-2090
80.
Kava-Kava administration reduces anxiety in perimenopausal women 总被引:1,自引:0,他引:1
OBJECTIVE: Disturbances of mood, such as anxiety and depression, increase in the perimenopausal period. Hormone replacement therapy or neuroactive drugs represent useful treatments for these disturbances but may be contraindicated or not accepted. Herein it was investigated the efficacy of Kava-Kava, an extract of Piper Methysticum, on mood of perimenopausal women. DESIGN: A 3-months randomized prospective open study investigating in perimenopausal women modifications induced by calcium supplementation (control; n=34), calcium plus Kava-Kava at the dose of 100 mg/day (n=15) or calcium plus Kava-Kava at the dose 200 mg/day (n=19). Anxiety was evaluated by the State Trait Anxiety Inventory (STAI); depression by the Zung's scale (SDS), and climacteric symptoms by the Greene's scale. Evaluations were performed at baseline and after 1 and 3 months. RESULTS: In the control group during the 3 months, anxiety, depression and climacteric symptoms tended to decline, but not significantly. During Kava-Kava anxiety declined (P<0.001) at 1 (-3.8+/-1.03) and 3 (-5.03+/-1.2) months, depression declined at 3 months (-5.03+/-1.4; P<0.002) and climacteric score declined (P<0.0006) at 1 (-2.87+/-1.5) and 3 (-5.38+/-1.3) months. Only the decline of anxiety induced by Kava-Kava was significantly greater than that spontaneously occurring in controls (P<0.009). CONCLUSIONS: The present data indicate that, in perimenopausal women, administration of Kava-Kava induces an improvement of mood, particularly of anxiety. 相似文献