全文获取类型
收费全文 | 1329篇 |
免费 | 64篇 |
国内免费 | 35篇 |
专业分类
耳鼻咽喉 | 21篇 |
儿科学 | 95篇 |
妇产科学 | 26篇 |
基础医学 | 131篇 |
口腔科学 | 37篇 |
临床医学 | 145篇 |
内科学 | 262篇 |
皮肤病学 | 35篇 |
神经病学 | 56篇 |
特种医学 | 198篇 |
外科学 | 142篇 |
综合类 | 27篇 |
预防医学 | 99篇 |
眼科学 | 16篇 |
药学 | 92篇 |
中国医学 | 3篇 |
肿瘤学 | 43篇 |
出版年
2023年 | 4篇 |
2022年 | 11篇 |
2021年 | 20篇 |
2020年 | 16篇 |
2019年 | 29篇 |
2018年 | 23篇 |
2017年 | 21篇 |
2016年 | 17篇 |
2015年 | 27篇 |
2014年 | 28篇 |
2013年 | 52篇 |
2012年 | 48篇 |
2011年 | 44篇 |
2010年 | 60篇 |
2009年 | 59篇 |
2008年 | 45篇 |
2007年 | 58篇 |
2006年 | 45篇 |
2005年 | 63篇 |
2004年 | 44篇 |
2003年 | 35篇 |
2002年 | 33篇 |
2001年 | 43篇 |
2000年 | 31篇 |
1999年 | 34篇 |
1998年 | 52篇 |
1997年 | 51篇 |
1996年 | 50篇 |
1995年 | 33篇 |
1994年 | 40篇 |
1993年 | 35篇 |
1992年 | 23篇 |
1991年 | 19篇 |
1990年 | 14篇 |
1989年 | 25篇 |
1988年 | 50篇 |
1987年 | 22篇 |
1986年 | 18篇 |
1985年 | 30篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 7篇 |
1976年 | 15篇 |
1975年 | 4篇 |
1969年 | 1篇 |
排序方式: 共有1428条查询结果,搜索用时 15 毫秒
91.
AS Grumach RC Carmona D Lazarotti MA Ribeiro RB Rozentraub ML Racz A Weinberg MMS Carneiro-Sampaio 《Acta paediatrica (Oslo, Norway : 1992)》1993,82(3):284-290
Breast milk samples from three groups of Brazilian women were evaluated: G1, mothers delivering term babies of low birth weight (n=16); G2, mothers delivering preterm babies of appropriate birth weight (n = 20); G3, mothers delivering term babies of appropriate birth weight ( n = 30). Milk samples were obtained at 48 h and on the 7th, 15th, 30th and 60th days after delivery and they were analyzed for lysozyme and total IgA levels and for the presence of specific antibodies against Poliovirus types I, II, III, Rotavirus, Herpes simplex virus, Varicella zoster and Cytomegalovirus. The groups were not statistically different in relation to mother's age, parity, type of delivery or socio-economic levels. IgA levels were higher in both low-birth-weight groups (G1 & G2) compared to the control group (G3) throughout the study period. Lysozyme levels decreased up to the 15th day, increasing thereafter up to the 60th day in all groups. Specific antibodies were detected throughout the study period, with no differences among groups. We conclude that breast milk composition of mothers delivering low-birth-weight babies (G1 & G2) was similar despite the different gestational ages. 相似文献
92.
Ballesteros García AI Lassaletta Atienza L Villafruela Sanz MA Alvarez Vicent JJ 《Acta otorrinolaringologica espanola》1999,50(1):72-74
Lingual abscesses have become extremely rare since the discovery of antibiotics, with only about 200 cases reported in the last 160 years. Diagnosis on the basis of clinical symptoms alone is quite difficult. Imaging studies are essential for the diagnosis of lingual abscesses and for their differentiation from related pathologies with similar clinical symptoms. We report a case of lingual abscess with otherwise unremarkable clinical findings that was diagnosed by CT scan. The etiology, pathophysiology, bacteriology, diagnosis, and treatment of these uncommon infections is discussed. 相似文献
93.
94.
Human neonatal fibroblasts in monolayer culture secrete insulin-like growth factor-binding proteins (IGFBPs), which may modulate IGF action. To examine whether an increase in extracellular concentrations of IGFBPs in response to IGF-I is due to the release of cell-associated IGFBPs, we measured secreted and cell-associated IGFBP-3 immunologically in fibroblast monolayers treated with IGF-I and IGF analogs with altered affinities for the IGF receptors and IGFBPs. IGFBP-3 in medium conditioned by fibroblasts treated with IGF-I was significantly increased (P < 0.05) compared with that in medium from untreated cultures; concomitantly, cell-associated IGFBP-3 was significantly decreased (P < 0.05). [Ser24]IGF-I (reduced affinity for IGF receptors) also increased secreted IGFBP-3 and decreased cell-associated IGFBP-3. In contrast, IGFBP-3 concentrations in medium conditioned by fibroblasts treated with B-chain IGF-I (reduced affinity for IGFBPs) were not significantly increased, and cell-associated IGFBP-3 was unchanged. Heparin, which releases proteins attached to cell surface proteoglycans, increased medium concentrations of IGFBP-3 and decreased IGFBP-3 binding to fibroblasts. An IGFBP of 29-31 kilodaltons (kDa) showed a pattern of regulation similar to that of IGFBP-3, while a third IGFBP, of 24 kDa, was decreased in IGF-I- and [Ser24]IGF-I-conditioned medium and unchanged by B-chain IGF-I and heparin. Preincubation with transforming growth factor-beta 1 (TGF beta 1), which stimulates fibroblast IGFBP-3 production, or human serum-derived IGFBP-3 did not increase cell-associated IGFBP-3. Analysis of total RNA isolated from fibroblasts revealed that IGFBP-3 mRNA was increased by TGF beta 1, but not by IGF-I. These data suggest that IGFs and TGF beta 1 release fibroblast IGFBPs by distinct mechanisms: IGFs by binding and subsequent release of cell-associated IGFBP-3 and 29- to 31-kDa IGFBP, and TGF beta 1 by increased de novo synthesis of IGFBP-3. 相似文献
95.
96.
97.
98.
99.
Amato D Alvarez-Aguilar C Castañeda-Limones R Rodriguez E Avila-Diaz M Arreola F Gomez A Ballesteros H Becerril R Paniagua R 《Kidney international. Supplement》2005,(97):S11-S17
BACKGROUND: The present study was primarily designed to assess the prevalence of chronic kidney disease in a Mexican urban population residing in Mexico and to evaluate certain biologic and socioeconomic conditions as risk factors for the development of renal disease. METHODS: A population-based cross-sectional survey was conducted, which included 3564 patients of either gender aged >18 years, who were randomly selected from lists of patients assigned to primary care facilities in the city of Morelia. A questionnaire about personal current health status, kidney disease, diabetes, hypertension, or heart disease in close relatives, anthropometric and blood pressure measurements, and blood and urine samples to measure glucose, blood urea nitrogen, and creatinine was obtained for each patient. Creatinine clearance (Ccr) was calculated by the Cockcroft-Gault formula. Patients were classified in 1 of the 5 Ccr categories established by the Kidney Disease Outcomes Quality Initiative guidelines. RESULTS: The prevalence rate of Ccr < 15 mL/min was 1142 per million population, and that of Ccr <60 mL/min 80,788 per million population. Alcohol and tobacco consumption, female gender, age >65 years, educational level < primary school, and income < US $4.00/day were significantly associated with reduced Ccr. CONCLUSION: Chronic kidney disease prevalence in this population is similar to that seen in industrialized countries. If these figures are similar to those of the entire Mexican population, only l out of 4 patients requiring renal replacement therapy in the country currently has access to it. 相似文献
100.
Omar Hernández Pérez Ramón Aznar Luz Ma. Ballesteros J. Domingo Méndez Adolfo Rosado 《Contraception》1976,14(4):421-433
Using the technique of affinity chromatography in poly (U) sepharose, we have studied the relative concentration of total, messenger, ribosomal and transfer RNA in the normal and the copper treated human endometrium, attempting to further elucidate the mechanism of the Cu-T200 intrauterine device. The transition from the proliferative to the secretory endometrium in normal women was found to be accompanied by significative increases in total RNA (from 5.19 ± 0.7 to 7.9 ± 0.7 mg/g.w.w.), in mRNA (from 0.22 ± 0.026 to 0.34 ± 0.04) and in rRNA (from 3.52 ± 0.45 to 6.68 ± 0.85). The relative proportions of bound and free mRNA were also modified by endometrial maturation changing from 70% bound mRNA in the proliferative to 83% in the secretory phase. Intrauterine copper release seems to particularly affect RNA metabolism in the secretory phase of the menstrual cycle. Thus while during the proliferative phase only the concentration of tRNA and the proportion of bound to free mRNA were found to be modified by the Cu-T200, this IUD induced significative decreases in all the RNA parameters studied, with the exception of the RNA/DNA ratio. 相似文献