全文获取类型
收费全文 | 19016篇 |
免费 | 1081篇 |
国内免费 | 147篇 |
专业分类
耳鼻咽喉 | 220篇 |
儿科学 | 502篇 |
妇产科学 | 664篇 |
基础医学 | 2069篇 |
口腔科学 | 533篇 |
临床医学 | 1567篇 |
内科学 | 3785篇 |
皮肤病学 | 379篇 |
神经病学 | 887篇 |
特种医学 | 724篇 |
外国民族医学 | 11篇 |
外科学 | 3350篇 |
综合类 | 340篇 |
现状与发展 | 2篇 |
一般理论 | 11篇 |
预防医学 | 1636篇 |
眼科学 | 545篇 |
药学 | 1753篇 |
中国医学 | 138篇 |
肿瘤学 | 1128篇 |
出版年
2024年 | 17篇 |
2023年 | 249篇 |
2022年 | 778篇 |
2021年 | 1119篇 |
2020年 | 608篇 |
2019年 | 758篇 |
2018年 | 1022篇 |
2017年 | 599篇 |
2016年 | 628篇 |
2015年 | 636篇 |
2014年 | 895篇 |
2013年 | 1037篇 |
2012年 | 1513篇 |
2011年 | 1656篇 |
2010年 | 941篇 |
2009年 | 679篇 |
2008年 | 956篇 |
2007年 | 965篇 |
2006年 | 883篇 |
2005年 | 851篇 |
2004年 | 733篇 |
2003年 | 678篇 |
2002年 | 604篇 |
2001年 | 139篇 |
2000年 | 111篇 |
1999年 | 95篇 |
1998年 | 76篇 |
1997年 | 73篇 |
1996年 | 72篇 |
1995年 | 64篇 |
1994年 | 59篇 |
1993年 | 50篇 |
1992年 | 47篇 |
1991年 | 55篇 |
1990年 | 54篇 |
1989年 | 46篇 |
1988年 | 49篇 |
1987年 | 46篇 |
1986年 | 38篇 |
1985年 | 38篇 |
1984年 | 39篇 |
1983年 | 36篇 |
1982年 | 33篇 |
1981年 | 23篇 |
1980年 | 21篇 |
1978年 | 16篇 |
1977年 | 14篇 |
1976年 | 17篇 |
1974年 | 13篇 |
1973年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
32.
PURPOSE: To determine if there is an association between the timing of surgical intervention for congenital cataract within the first 12 weeks of life and the prevalence of postoperative complications. METHODS: We performed a retrospective review of records from 1990 to 2000 of infants who underwent surgery for congenital cataract within the first 12 weeks of life. Eighty eyes in 55 children were involved with a minimum follow up of 6 months. Bilateral cataracts were present in 25 and monocular cataracts in 30 infants. A limbal approach lensectomy-vitrectomy was performed in all infants. Children with aphakia were rehabilitated with contact lens or glasses. Operative and postoperative complications-including glaucoma, nystagmus, strabismus, retinal detachment, and posterior capsule opacification/secondary membranes-were recorded. Ocular and systemic associations were noted. Statistical analysis was carried out with classification and regression trees (CART). RESULTS: The mean age at the time of surgery was 31.5 +/- 23.3 days (median, 26.5; range, 2 to 84). Mean follow up from the time of surgery was 2.85 +/-1.9 years (median, 2; range, 0.5 to 8). Persistent fetal vasculature (persistent hyperplastic primary vitreous) was present in 14 eyes. One infant with bilateral persistent fetal vasculature had bilateral retinal dysplasia and was excluded from the analysis. Glaucoma developed in 12 infants (22%); nystagmus was present in 18 infants (33%); strabismus developed in 28 infants (52%); and secondary membranes developed in 7 eyes (13%). CART analysis suggests that glaucoma is more prevalent in infants when the surgery was performed between 13.5 and 43 days of life (CART = 0.370); nystagmus when surgery is performed between 48 and 84 days of life (CART = 0.500); strabismus when surgery is performed between 55.5 and 84 days of life (CART = 0.600); and secondary membranes when surgery is performed between 26.5 and 40 days of life (CART = 0.4). CONCLUSIONS: Our data suggest that the first 2 weeks of life comprise the most favorable time for decreasing postoperative complications resulting from surgical intervention for infants presenting with cataracts within the first 12 weeks of life. 相似文献
33.
Rebecca Suckling Mohamed Morsy Eric S Chemla 《Nephrology, dialysis, transplantation》2007,22(3):970-971
Sir, The expansion of haemodialysis includes older patients withcomorbidities, poor quality vessels, unsuitable for transplantationor peritoneal dialysis. Vascular access complications accountfor 20% of hospital admissions [1]. With exhausted sites inupper extremities, unusual sites for arteriovenous grafts formationare used [2]. The 相似文献
34.
35.
36.
Inactivation of Notch1 impairs VDJbeta rearrangement and allows pre-TCR-independent survival of early alpha beta Lineage Thymocytes 总被引:12,自引:0,他引:12
Notch proteins influence cell fate decisions in many developmental systems. During lymphoid development, Notch1 signaling is essential to direct a bipotent T/B precursor toward the T cell fate, but the role of Notch1 at later stages of T cell development remains controversial. We have recently reported that tissue-specific inactivation of Notch1 in immature (CD44(-) CD25(+)) thymocytes does not affect subsequent T cell development. Here, we demonstrate that loss of Notch1 signaling at an earlier (CD44(+)CD25(+)) developmental stage results in severe perturbation of alpha beta but not gamma delta lineage development. Immature Notch1(-/-) thymocytes show impaired VDJ beta rearrangement and aberrant pre-TCR-independent survival. Collectively, our data demonstrate that Notch1 controls several nonredundant functions necessary for alpha beta lineage development. 相似文献
37.
Diabetes mellitus is associated with disturbances in haemostasis that could contribute to the development of thrombotic complications.The present study was undertaken to determine the behavior of coagulation variables and fibrinolytic system in diabetes mellitus. Forty five diabetic patients and forty five matched controls were evaluated by doing the following haemostatic parameter, prothrombin time, partial thromboplastin time, thrombin time, coagulation factors assay II, VII, IX, & plasma fibrinogen, ADP-induced platelet aggregation, protein C, a2- antiplasmin, PAI and FDPs. Generally diabetic patients have high levels of fibrinogen, a2- antiplasmin, & PAI and lower level of protein C. Other haemostatic parameters did not show statistically significant difference between diabetic patients and control group. Significantally elevated levels of PAI, a2- antiplasmin together with low protein C level in diabetic patients may result in the disturbance of haemostatic balance favoring thrombotic events. Conclusion: High levels of plasma fibrinogen, a2A- antiplasmin with low plasma protein C activity could lead to a prothrombotic tendency in insulin dependent diabetic patients. Moreover, in non-insulin dependent diabetic patients, the above mentioned parameters together with high levels of ADP-induced platelet aggregation and plasminogen activator inhibitor may increase the risk of thrombotic complications. Obesity can be considered as an additional risk factor for development of thrombosis in diabetic patients. 相似文献
38.
Mohamed Magdy Abdel-Moteleb 《Macromolecular chemistry and physics.》1991,192(3):543-551
The real part of the relative permittivity ?′r of some cellulosic materials contaminated with commercial impurities and NaCl (determined as weight percent ash contents), and that of the purified fibres, as well as their hydrolysed residues, free of such contaminations, was measured in the frequency range 102 Hz ≤ f ≤ 105 Hz and in the temperature range 283,15 K ≤ T ≤ 333,15 K. Additional measurements of the imaginary part of relative permittivity ?″r have been carried out in the same frequency and temperature ranges for hydrocellulose samples free of inorganic impurities and contaminated with NaCl. The results obtained show that the variation with temperature of the relative permittivity of the samples examined exhibits a change in slope in the vicinity of 303,15 K except for hydrocellulose samples free of impurities. They further show that the presence of inorganic contaminations has a significant effect on the magnitude of the relative permittivity and its variation with temperature, particularly at low frequency. In the case of samples contaminated with inorganic impurities, interfacial polarization is responsible for the anomalous dielectric behaviour observed with the examined samples. 相似文献
39.
40.
Protein composition of tomato spotted wilt virus 总被引:2,自引:0,他引:2
Analysis of the protein composition of tomato spotted wilt virus (TSWV), purified by an improved procedure, by polacrylamide gel electrophoresis, revealed three major structural proteins (of MW 84,000, 50,000, and 29,000d) and a minor one of MW 220,000d. The three major proteins constitute about 98% of the total viral protein and all three were shown to be glycoproteins. One of the major proteins (MW 29,000d) and the minor protein were shown to be associated with subviral particles isolated by treatment of virus with the nonionic detergent Nonidet P-40. Only traces of the other two proteins were detected in the subviral particles.Synthesis of virus-induced proteins in TSWV-infected tobacco leaves was studied by labeling infected and healthy tissue with [3H]and [14C]valine, respectively. The labeled tissues were then fractionated into crude subcellular fractions and protein patterns of healthy and infected tissues were compared by coelectrophoresis on polyacrylamide gels. Only one virus-specific protein (of MW 49,000d) was detected in the virus-enriched fractions; this corresponded with the viral structural protein of MW 50,000d. 相似文献