全文获取类型
收费全文 | 2206篇 |
免费 | 94篇 |
国内免费 | 51篇 |
专业分类
耳鼻咽喉 | 19篇 |
儿科学 | 62篇 |
妇产科学 | 47篇 |
基础医学 | 178篇 |
口腔科学 | 23篇 |
临床医学 | 291篇 |
内科学 | 325篇 |
皮肤病学 | 44篇 |
神经病学 | 72篇 |
特种医学 | 193篇 |
外科学 | 187篇 |
综合类 | 309篇 |
预防医学 | 200篇 |
眼科学 | 31篇 |
药学 | 208篇 |
3篇 | |
中国医学 | 99篇 |
肿瘤学 | 60篇 |
出版年
2023年 | 12篇 |
2022年 | 22篇 |
2021年 | 36篇 |
2020年 | 37篇 |
2019年 | 19篇 |
2018年 | 14篇 |
2017年 | 32篇 |
2016年 | 27篇 |
2015年 | 39篇 |
2014年 | 53篇 |
2013年 | 65篇 |
2012年 | 109篇 |
2011年 | 99篇 |
2010年 | 93篇 |
2009年 | 96篇 |
2008年 | 121篇 |
2007年 | 118篇 |
2006年 | 107篇 |
2005年 | 91篇 |
2004年 | 51篇 |
2003年 | 35篇 |
2002年 | 38篇 |
2001年 | 52篇 |
2000年 | 43篇 |
1999年 | 30篇 |
1998年 | 35篇 |
1997年 | 44篇 |
1996年 | 48篇 |
1995年 | 38篇 |
1994年 | 41篇 |
1993年 | 31篇 |
1992年 | 9篇 |
1991年 | 18篇 |
1990年 | 18篇 |
1989年 | 19篇 |
1988年 | 25篇 |
1987年 | 21篇 |
1986年 | 10篇 |
1985年 | 26篇 |
1984年 | 22篇 |
1983年 | 12篇 |
1980年 | 12篇 |
1977年 | 9篇 |
1959年 | 41篇 |
1958年 | 66篇 |
1957年 | 75篇 |
1956年 | 73篇 |
1955年 | 83篇 |
1954年 | 51篇 |
1948年 | 11篇 |
排序方式: 共有2351条查询结果,搜索用时 15 毫秒
1.
乐敏飞 《中国公共卫生管理》2016,(4):477-479
目的调查宁波市北仑区0~14岁儿童哮喘发病率、发病规律及危险因素,为制定防治措施提供参考。方法2013年1月-2014年1月,采用整群抽样法抽取北仑区19所学校0~14岁儿童为调查对象进行问卷调查,对筛查出的疑似哮喘儿童进行确诊,并对其人口学特征进行分析,采用logistic回归方程分析危险因素。结果调查收回有效问卷23 781份,共检出哮喘患儿534例,发病率为2.25%,男女发病率比例为1.92:1。其中发病较轻患儿占44.01%,中度占31.46%,重度占24.53%。发病时间以换季、冬季为主,分别占35.96%、32.02%。多因素logistic回归分析显示,呼吸道感染、药物过敏史、家族过敏史和食物过敏史是儿童哮喘发病的危险因素(P<0.05)。结论北仑区儿童哮喘发病率较高,具有性别和季节发病差异,应加大对患病危险因素的宣传,规范标准化治疗方案,减少儿童哮喘疾病的发生。 相似文献
2.
Reactive oxygen species and human spermatozoa: physiology and pathology 总被引:20,自引:1,他引:19
The role of reactive oxygen species (ROS) in the pathophysiology of human sperm function has been emphasized in recent years. ROS production in semen has been associated with loss of sperm motility, decreased capacity for sperm–oocyte fusion and loss of fertility. There is a current presumption that the most prolific source of ROS in sperm suspensions is an NADPH oxidase located in leukocytes or in spermatozoa which produces superoxide which is further converted to peroxide by the action of superoxide dismutase. Hydrogen peroxide has been recognized as the most toxic oxidizing species for human spermatozoa, which are very sensitive to lipid peroxidation owing to the high content of polyunsaturated fatty acids in their plasma membrane, though this is not the sole mechanism by which sperm function might be impaired by ROS. Although the excessive production of ROS is detrimental to human spermatozoa, there is a growing body of evidence which suggests that ROS are also involved in the physiological control of some sperm functions. This review focuses on the nature and source of the ROS generated by human spermataozoa as well as their operational mechanisms and their effects, which may be detrimental or beneficial. 相似文献
3.
4.
5.
6.
研究不同微生物诱导家蝇幼虫表达的抗菌肽特性.用3种不同的病源菌通过针刺感染的方法诱导家蝇幼虫表达抗菌肽,通过Sephadex G25分离,用Hult mark改进法和抑菌圈测定法作抑菌试验,用毛细管电泳(CE)分析不同微生物诱导得到的抗菌肽样品差异,检测抗菌肽的热稳定性和酸碱耐受性.发现不同微生物诱导产生的家蝇抗菌肽具有广谱抑菌性,但不同样品对不同病源菌抑菌活性有差异,不同测定抑菌效果的方法对抑菌结果有影响,各种抗菌肽样品CE蛋白谱具有明显不同.抗菌肽样品都具有热稳定性和酸碱耐受性.说明不同微生物诱导产生的家蝇抗菌肽类型以及抗菌肽含量与诱导源有关,抗菌肽为家蝇幼虫体内固有成分,诱导增加了抗菌肽的表达量同时刺激新抗菌肽的产生.用志贺氏菌、金黄色葡萄球菌、鼠伤寒沙门氏菌诱导家蝇幼虫可产生较多含量高活性好的抗菌肽. 相似文献
7.
J O de Boer A J van Es L E Voorrips F Blokstra J E Vogt 《European journal of clinical nutrition》1988,42(12):983-997
Some studies on energy metabolism of men and women in Third World countries suggested that their basal metabolic rate (BMR) is lower compared to BMRs of people in Northern European and American countries. It is, however, not clear whether this results from ethnic factors, climate or adaptation to, for instance, a low energy intake. A study on energy requirements of people from Third World countries has therefore been performed. People with different ethnic backgrounds participated; they were divided into four ethnic groups: 8 African males, 7 Asian males of Mongolian origin (Asian-M), 8 Asian males of Caucasian origin (Asian-C) and 7 European males, who formed the control group. The participants from outside Europe had spent at least 3 months in the Netherlands. All participants consumed a diet (12 per cent of energy from protein, 22 per cent from fat and 66 per cent from carbohydrate) during 8 d. The dietary energy given to each individual was estimated to maintain energy equilibrium during the experiment. The last 3 nights and 2 days were spent in an indirect whole-body calorimeter. Two 24-h energy expenditure (24hEE) measurements were performed on each subject. The environmental temperature inside the calorimeter was 22.0-24.5 degrees C. Physical activity was light, mainly sedentary, with 75 min bicycling at 15 W. The Asian subjects had a significantly lower body weight and fat-free mass than the Europeans. Energy requirement (ER), 24hEE and EE during the night (8 h sleep) was lower in the Asian and African subjects compared to the Europeans, but the difference only reached significance for the Asian-C and African males. When ER, 24hEE and EE-night were expressed in relation to body weight and fat-free mass the Asian groups showed a higher ER and higher EE than the Europeans. This result is contrary to findings of others and may be caused eg, by a higher body weight and fat-free mass of the European controls. Comparison of EE-night with BMR estimated from FAO/WHO/UNU equations showed that the EE-night was consistently lower by about 9 per cent. This suggests that EE during the night may not be predicted by the BMR estimated by widely used equations. This study does not give conclusive evidence that an ethnic factor is involved in energy metabolism in humans. 相似文献
8.
9.
胃癌组织中核基质蛋白的变化 总被引:1,自引:1,他引:0
目的:研究胃癌组织核基质蛋白的改变。方法:应用SDS-PAGE技术及Geneools定量分析软件,对22例胃癌组织及正常组织的核心基质蛋白进行了研究,结果:胃癌组织与正常组织比较,Mr为30000,28000的核基质蛋白表达量明显减少(P<0.05),不同分化类型及不同临床分期胃癌组织间比较,此种核基质蛋白表达量差异无统计学意义(P>0.05),结论:胃癌组织中核基质蛋白的改变可能在肿瘤的早期已经发生,是胃癌发生的早期分子事件。 相似文献
10.
MA Sevick B Piraino S Sereika T Starrett C Bender J Bernardini S Stark LE Burke 《Journal of renal nutrition》2005,15(3):304-311
OBJECTIVE: The purpose of this study was to pilot test an intervention to enhance the adherence of study participants to the hemodialysis dietary regimen. DESIGN: A single case study design was used to examine the potential effectiveness of the intervention over a 4-month period of time. SETTING: A dialysis center in southwestern Pennsylvania. PATIENTS: Of the five individuals entered into the study, one was male and four were female, four were black, and one was white. Participants were 63 to 70 years of age, and had been receiving dialysis for a median of 36 months (range, 18 to 84 months). INTERVENTION: The intervention included counseling to enhance self-efficacy, by a renal dietitian, paired with personal digital assistant-based dietary self-monitoring. Participants met twice per week with interventionists during the first 6 weeks, weekly during the second 6-week period, and biweekly in the final 4-week period. MAIN OUTCOME MEASURES: Monthly laboratory data regarding serum albumin, potassium, and phosphorus levels; Kt/V; and data on average monthly interdialytic weight gain were abstracted from the participants' medical records. C-reactive protein level was determined at baseline and at 4 months. RESULTS: Four of five study participants had an increase in serum albumin level from baseline to their final measurement, and one participant maintained a stable albumin level. Four of five participants also experienced a small increase in serum phosphorus level. Mixed results were obtained with regard to serum potassium and average monthly interdialytic weight gain. CONCLUSIONS: Because of the small sample and single case study design, caution must be used in drawing firm conclusions from this study. Data suggest that the intervention may result in improved dietary intake and improved serum albumin levels. With increased dietary intake, serum phosphorus levels may increase. Additional research is needed to determine the potential efficacy and cost-effectiveness of this intervention for improving dietary adherence. 相似文献