全文获取类型
收费全文 | 3780篇 |
免费 | 338篇 |
国内免费 | 199篇 |
专业分类
耳鼻咽喉 | 53篇 |
儿科学 | 91篇 |
妇产科学 | 104篇 |
基础医学 | 291篇 |
口腔科学 | 46篇 |
临床医学 | 388篇 |
内科学 | 456篇 |
皮肤病学 | 52篇 |
神经病学 | 102篇 |
特种医学 | 208篇 |
外科学 | 347篇 |
综合类 | 762篇 |
预防医学 | 306篇 |
眼科学 | 45篇 |
药学 | 432篇 |
7篇 | |
中国医学 | 421篇 |
肿瘤学 | 206篇 |
出版年
2024年 | 14篇 |
2023年 | 46篇 |
2022年 | 82篇 |
2021年 | 128篇 |
2020年 | 111篇 |
2019年 | 57篇 |
2018年 | 89篇 |
2017年 | 79篇 |
2016年 | 72篇 |
2015年 | 151篇 |
2014年 | 174篇 |
2013年 | 205篇 |
2012年 | 300篇 |
2011年 | 309篇 |
2010年 | 236篇 |
2009年 | 242篇 |
2008年 | 223篇 |
2007年 | 246篇 |
2006年 | 203篇 |
2005年 | 130篇 |
2004年 | 95篇 |
2003年 | 96篇 |
2002年 | 88篇 |
2001年 | 66篇 |
2000年 | 30篇 |
1999年 | 13篇 |
1998年 | 33篇 |
1997年 | 33篇 |
1996年 | 28篇 |
1995年 | 36篇 |
1994年 | 26篇 |
1993年 | 30篇 |
1991年 | 12篇 |
1990年 | 7篇 |
1989年 | 13篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 11篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 10篇 |
1982年 | 7篇 |
1980年 | 6篇 |
1959年 | 49篇 |
1958年 | 103篇 |
1957年 | 107篇 |
1956年 | 79篇 |
1955年 | 82篇 |
1954年 | 67篇 |
1949年 | 10篇 |
排序方式: 共有4317条查询结果,搜索用时 15 毫秒
21.
目的 评价腹腔镜下修补治疗十二指肠球部前壁溃疡穿孔的临床应用价值。方法 对我院2003年1月~2004年12月收治的42例青年十二指肠溃疡穿孔病例随机分组,20例接受腹腔镜下修补治疗,22例接受传统开腹修补。结果 两组术后胃肠功能恢复情况、术后使用镇痛药、平均住院时间差异均有显著性(P〈0.05),两组术后均无出血、中转开腹、再穿孔等并发症。结论 腹腔镜下修补治疗青年十二指肠球部前壁溃疡穿孔临床安全可行,应该作为首选方法在临床上推广应用。 相似文献
22.
Effects of cholestyramine on gallbladder and gastric emptying in obese and lean subjects 总被引:3,自引:0,他引:3
P. PORTINCASA † A. DI CIAULA V. PALMIERI G. P. VAN BERGE-HENEGOUWEN† G. PALASCIANO 《European journal of clinical investigation》1995,25(10):746-753
Abstract. Gallbladder stasis is frequent in obese subjects and may contribute to their increased risk for gallstone formation. The bile salt sequestrant cholestyramine acutely enhances postprandial gallbladder emptying in lean subjects, through dis-inhibition of a negative feedback between intraluminal bile salts and CCK release. In this study the effect of cholestyramine on both gallbladder and gastric antrum dynamics were studied by realtime ultrasonography in 12 obese and 15 lean subjects. For the acute study, on different days, subjects ingested a liquid meal (two egg yolks plus water 200 mL, 50 kJ) or a meal with 4g cholestyramine. Gallbladder emptying was impaired in obese patients who had significantly larger fasting gallbladder volume (39.4 ± 6.9 vs. 21.6 ± l.7mL, P <0.02), larger residual volume (12.3 ± 1.8 vs. 4.0 ± 0.5ml, P < 0.0006) and slower emptying time ( T /2: 33 ± 2 vs. 21 ± 2 min, P < 0.05) than lean subjects. Integrated antral emptying was also less in obese than lean subjects (5521 ± 578 vs. 7908 ± 491 % 120min-1 , P <0.02). Cholestyramine enhanced postprandial gallbladder emptying in both obese and lean subjects. Gastric emptying was delayed with cholestyramine in lean but not obese subjects. For the chronic study, after 1 month therapy with cholestyramine (4 g every 2 days), the motility tests were repeated in nine obese subjects. Gallbladder and gastric responses to a test meal, with or without cholestyramine, were preserved. We conclude that both gallbladder and antral emptying of a liquid test meal are impaired in obese subjects. Gallbladder emptying improves after acute administration of a low dose cholestyramine with test meal. This effect is sustained after 1 month treatment with a low dose of cholestyramine and does not interfere with gastric emptying of obese patients. Cholestyramine may improve gallbladder hypomotility in obese people. 相似文献
23.
目的 探索如何抑制嗜酸细胞的趋化作用,选择β-趋化因子巨噬细胞炎性蛋白4(MIP4)的突变性(Met-MIP4)作为趋化因子受体3的拮抗剂,将Met-MIP4基因在原核细胞中进行表达。方法 设计MIP4基因的PCR引物并进行氨基酸突变,将MIP4N末端的丙氨酸突变为蛋氨酸,以正常人肺酸突变,将MIP4N末端的丙氨酸突变为蛋氨酸。以正常人肺cDNA文库为模板,PCR方法获取Met-MIP4基因,克隆入载体pUC19,测序验证序列已得到突变,将正确的基因插入到GST融合表达载体pGEX-4T中,以IPTG诱导表达。结果 PCR产物为220bp左右的片段,连接入pUC19质粒后测序验证获得正确突变,构建的pGEX-4T融合表达载体在大肠杆菌中表达,经SDS-PAGE凝胶电泳显示有大小约34kU的新生融合蛋白表达。结论 成功突变并克隆了β-趋化因子MIP4基因,SDS-PAGE表明,与GST融合的Met-MIP4突变体已得到表达,为进一步研究其生物学活性奠定了基础。 相似文献
24.
V. EVANGELISTA G. DE BERARDIS† L. TOTANI F. AVANZINI‡ C. B. GIORDA§ L. BRERO¶ G. LEVANTESI G. MARELLI†† M. PUPILLO‡‡ G. IACUITTI‡ G. POZZOLI‡ P. DI SUMMA¶ E. NADA§ G. DE SIMONE G. DELL'ELBA C. AMORE S. MANARINI R. PECCE A. MAIONE† G. TOGNONI† A. NICOLUCCI† 《Journal of thrombosis and haemostasis》2007,5(11):2197-2203
BACKGROUND: The percentage of diabetic patients who do not benefit from the protective effect of aspirin is larger than in other populations at cardiovascular risk. OBJECTIVE: We compared the ability of aspirin to suppress TxA2 and platelet activation in vivo, in type-2 diabetics vs. high-risk non-diabetic patients. METHODS: Urinary 11-dehydro-TXB2, plasma sCD40 L, and sP-selectin were measured, together with indices of low-grade inflammation, glycemic control, and lipid profile, in 82 patients with type-2 diabetes and 39 without diabetes, treated with low doses of aspirin. RESULTS: Urinary 11-dehydro-TxB2, plasma sCD40L and sP-selectin were significantly higher in diabetics than in controls: [38.9 (27.8-63.3) vs. 28.5 (22.5-43.9) ng mmol(-1) of creatinine, P = 0.02], [1.06 (0.42-3.06) vs. 0.35 (0.22-0.95) ng mL(-1); P = 0.0001], [37.0 (16.8-85.6) vs. 20.0 (11.2-35.6) ng mL(-1), P = 0.0001], respectively. The proportion of individuals with diabetes increased across quartiles of 11-dehydro-TxB2, sCD40L, and sP-selectin, with the highest quartiles of 11-dehydro-TxB2, sCD40L and sP-selectin, including 66%, 93.3%, and 93.3% of individuals with diabetes. Markers of platelet activation positively correlated with indices of glycemic control but not with markers of low-grade inflammation. CONCLUSIONS: Platelet dysfunction associated with insufficient glycemic control, may mediate persistent platelet activation under aspirin treatment. 相似文献
25.
C. NAPOLI A. LIGUORI P. SORICE A. DI BENEDETTO S. CIAFRE T. POSCA N. DI IESO F. P. D'ARMIENTO 《Journal of internal medicine》1996,240(6):389-394
Background. Arterial hypertension is a significant risk factor for the high rate of cardiovascular disease in chronic uraemic (CU) patients. Any role that hypertension may play in CU patient outcomes assumes added significance. The elevation of some hormonal factors in early clinical stage could represent a valuable marker of cardiac disease in CU. Aim. This study first investigated the role of several hormones on cardiac diastolic properties in CU patients. Moreover, the study investigated the association of hypertension with both diastolic function and release of vasoactive hormones in CU patients. Results. We have reported that the early impairment of diastolic function is correlated with the elevation of both circulating plasma atrial natriuretic factor and endothelin-1 (ET-1) in hypertensive CU patients. Since the effect of ET-1 on diastolic function is still poorly understood, we have investigated also this issue. In eight additional patients with reduced E/A ratio, but without uraemia, hypertension or chronic heart failure, we have showed a high inverse correlation between the values of E/A ratio and ET-1 plasma concentrations. Conclusions. These results strongly suggest that the elevation in ET-1 levels was correlated with diastolic dysfunction in man. This phenomenon may have important pathophysiological implications suggesting the possibility of an early therapeutic approach in these patients. 相似文献
26.
Synergistic effect of deoxyspergualin (DSP) and cyclosporin A (CsA) in the prevention of spontaneous autoimmune diabetes in BB rats 下载免费PDF全文
R DI MARCO P ZACCONE G MAGRO S GRASSO M LUNETTA W BARCELLINI V M NICOLOSI P L MERONI F NICOLETTI 《Clinical and experimental immunology》1996,105(2):338-343
Dose-dependent side effects are frequently observed with immunosuppressive drugs of potential relevance for the immunotherapy of insulin-dependent diabetes mellitus (IDDM), such as CsA and DSP. If CsA and DSP acted synergistically in vivo, their combined use would allow using each compound at lower doses than those required when each drug is given in monotherapy. Consequently, dose-dependent side effects could be reduced and the therapeutic activity maintained or even enforced. Toward this end we studied the effects of combined treatment with CsA and DSP on the course of IDDM in the diabetes-prone (DP)-BB rat. The results show that two ‘low’ doses of CsA (2mg/kg) and DSP (1mg/kg) that are clinically ineffective in suppressing IDDM development in BB rats when administered alone under a prolonged prophylactic regimen (30–105 days old), may successfully prevent, but not cure, the disease when given contemporaneously under the same experimental conditions. The combined treatment was well tolerated, and no side effects were noticed. These data suggest that the combined use of CsA and DSP may deserve consideration for its possible application in the prevention/treatment of human IDDM and other autoimmune diseases. 相似文献
27.
Airway eosinophilia and expression of interleukin-5 protein in asthma and in exacerbations of chronic bronchitis 总被引:6,自引:0,他引:6
M. SAETTA A. DI STEFANO P. MAESTRELLI G. TURATO CE. MAPP M. PIENO G. ZANGUOCHI G. DEL PRETE† L. M. FABBRI 《Clinical and experimental allergy》1996,26(7):766-774
Background An increased nutnber of eosinophils in the bronchial mucosa has been demonstrated both in asthma and in exacerbations of chronic bronchitis. Oiyective To investigate whether the airway eosinophilia present in asthma and in chronic bronchitis during exacerbations is associated with interleukin (IL)-5 protein expression in the bronchial mucosa. Methods We obtained bronchial biopsies in 18 subjects with asthma (four intrinsic, seven extrinsic and seven occupational) and in II subjects with chronic bronchitis examined during an exacerbation. The findings were compared wilh those of bronchial biopsies from 10 subjects with chronic bronchitis examined under baseline conditions and from seven normal subjects, taken as controls. By immunohistochemistry, we assessed the expression of IL-5 protein and the number of eosinophils (EG2), mast cells ftryptase), and T-lymphocytes (CD3) in the submucosa. Results As compared with controls, the number of eosinophils was increased to a similar degree in both asthma (P < 0.001) and in exacerbations of ehronic bronchitis (P < 0.001). whereas the number of I L-5 immunopositive cells was increased significantly only in asthma (P < 0.01). No diflerences were observed in the number of tnast cells and T-lymphocytes between the four groups of subjects examined. Conciusions This study shows that the degree of airway eosinophilia is similar in asthma and in exacerbations of ehronic bronchitis, but only in asthma is it associated with an increased expression of I L-5 protein in the bronchial tnucosa. 相似文献
28.
目的观察NOD/SCID小鼠免疫状况和生育力特征,并分析NK细胞亚群对同基因交配组合NOD/SCID×NOD/SCID妊娠结局的影响。方法采用流式细胞术对未孕和孕13.5 d的NOD/SCID小鼠进行淋巴细胞表型分析,并系统地观察和比较NOD/SCID×NOD/SCID和BALB/c×BALB/c小鼠的生育力特征。分别采用多聚次黄苷酸-胞苷酸(polyinosinic-polycytidylic acid,poly I∶C)或抗asialoGM1单抗(anti-asialo GM1)刺激或抑制NK细胞活性,并分别观察这些因素对妊娠结局的影响。结果与对照组NOD/SCID小鼠相比,poly I∶C处理组NOD/SCID×NOD/SCID小鼠平均每窝产仔数增多,而注射抗asialo GM1单抗则使胚胎吸收率增高,进而平均每窝产仔数显著减少。结论在NOD/SCID小鼠孕期母-胎界面保持适当水平的NK细胞活性对妊娠结局有利。 相似文献
29.
目的: 研究肾上腺髓质素( adrenomedullin, ADM)抑制豚鼠心室肌细胞L-型钙通道的信号转导机制。方法: 应用全细胞膜片钳技术,记录应用ADM(1-100 nmol·L-1)前后L-型钙电流(ICa,L),以及分别记录应用ADM特异性受体拮抗剂ADM22-52(100 nmol·L-1)+ADM(100 nmol·L-1)、蛋白激酶A (PKA) 特异性拮抗剂H-89(10 μmol·L-1) + ADM(100 nmol·L-1)、蛋白激酶C (PKC) 特异性拮抗剂PKC19-36(10 μmol·L-1)+ADM(100 nmol·L-1)、PKC特异性激动剂PMA(1 μmol·L-1)前后ICa,L。结果: ADM(1-100 nmol·L-1)浓度依赖性地抑制豚鼠心室肌细胞ICa,L,并可被ADM22-52(100 nmol·L-1)完全阻断;H-89(10 μmol·L-1)对ADM抑制ICa,L的作用无影响。PKC19-36(10 μmol·L-1)可完全阻断ADM 对ICa,L的抑制效应,且PMA(1 μmol·L-1)可模拟ADM 对ICa,L的抑制效应。结论: ADM作用于特异性ADM受体可浓度依赖性地抑制豚鼠心室肌细胞ICa,L,此作用有可能与PKC激活相关。 相似文献
30.
表皮生长因子影响肿瘤患者舌苔变化的分子机制研究 总被引:12,自引:0,他引:12
目的 研究表皮生长因子(EGF)对食管癌细胞Eca-109细胞周期及表皮生长因子受体(EGF-R)表达的影响,探讨EGF促进肿瘤患者舌苔增厚的分子机制。方法 应用流式细胞术,检测EGF-R的表达和细胞周期。结果 EGF能明显促进Eca-109细胞膜上EGF-R的表达,使细胞增殖活性大大增强。结论EGF有是通过促进EGF-R的表达影响舌苔形成。 相似文献