全文获取类型
收费全文 | 1029篇 |
免费 | 71篇 |
国内免费 | 2篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 20篇 |
妇产科学 | 7篇 |
基础医学 | 111篇 |
口腔科学 | 33篇 |
临床医学 | 178篇 |
内科学 | 270篇 |
皮肤病学 | 14篇 |
神经病学 | 55篇 |
特种医学 | 33篇 |
外科学 | 66篇 |
综合类 | 32篇 |
一般理论 | 3篇 |
预防医学 | 152篇 |
眼科学 | 11篇 |
药学 | 74篇 |
中国医学 | 1篇 |
肿瘤学 | 40篇 |
出版年
2023年 | 5篇 |
2022年 | 6篇 |
2021年 | 10篇 |
2020年 | 5篇 |
2019年 | 11篇 |
2018年 | 13篇 |
2017年 | 16篇 |
2016年 | 16篇 |
2015年 | 21篇 |
2014年 | 28篇 |
2013年 | 50篇 |
2012年 | 66篇 |
2011年 | 68篇 |
2010年 | 35篇 |
2009年 | 36篇 |
2008年 | 62篇 |
2007年 | 60篇 |
2006年 | 64篇 |
2005年 | 62篇 |
2004年 | 49篇 |
2003年 | 51篇 |
2002年 | 47篇 |
2001年 | 30篇 |
2000年 | 24篇 |
1999年 | 28篇 |
1998年 | 15篇 |
1997年 | 13篇 |
1996年 | 9篇 |
1995年 | 14篇 |
1994年 | 6篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1976年 | 5篇 |
1974年 | 5篇 |
1973年 | 8篇 |
1972年 | 16篇 |
1971年 | 9篇 |
1970年 | 12篇 |
1969年 | 6篇 |
1968年 | 17篇 |
1967年 | 10篇 |
1966年 | 10篇 |
1965年 | 8篇 |
排序方式: 共有1102条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
The relationship between the number of people vaccinated for an infectious disease and the resulting decrease in incidence of the disease is not straightforward and linear because many independent variables determine the course of infection. However, these variables are quantifiable and can therefore by used to model the course of an infectious disease and impact of mass vaccination. Before one can construct a model, one must know for any specific infectious disease the number of individuals in the community protected by maternally derived antibodies, the number susceptible to infectious the number infected but not yet infectious (i.e., with latent infection), the number of infectious individuals, and the number of recovered (i.e., immune) individuals. Compartmental models are sets of differential equations which describe the rates of flow of individuals between these categories. Several major epidemiologic concepts comprise the ingredients of the model: the net rate of infection (i.e., incidence), the per capita rate of infection, the Force of Infection, and the basic reproductive rate of infection. When a community attains a high level of vaccination coverage, it is no longer necessary to vaccinate everyone because the herd immunity of the population protects the unvaccinated because it lowers the likelihood of their coming into contact with an infectious individual. Many infections that confer lasting immunity tend to have interepidemic periods when the number of susceptibles is too low to sustain an epidemic. Mass vacination programs reduce the net rate of transmission of the infective organism; they also increase the length of the interepidemic period. Many diseases primawrily associated with children have much more serious consequences in older people and the question arises as to at what point childhood immunization will successfully prevent the more dangerous incidence of the disease in older cohorts. Mathematical models of disease transmission enable one to predict the course of epidemics, design mass vaccination programs, and be guided as to what are the relevant data that should be collected. 相似文献
5.
This report describes the postcontrast MR findings of Wernicke encephalopathy seen in a malnourished 11-year-old boy. The examination showed increased signal on T2-weighted images in the periaqueductal gray matter and medial thalami. On T1-weighted acquisition, these areas showed decreased signal intensity, but on postcontrast T1-weighted examination, they showed moderately intense enhancement. Also noted on the postcontrast examination was mamillary body enhancement. 相似文献
6.
Pinocytic rates of macrophages from mice immunized against Toxoplasma gondii and macrophages stimulated to inhibit toxoplasma in vitro. 总被引:2,自引:0,他引:2
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The rate of pinocytosis by macrophages when measured by uptake of horseradish peroxidase was significantly reduced during toxoplasma infection of the cells in vitro when the macrophages were from toxoplasma-immune mice and when control cells were stimulated in vitro to inhibit toxoplasma multiplication. There was, however, no direct correlation between reduced pinocytosis in this model and inhibition or enhancement of toxoplasma multiplication. We conclude that a reduced pinocytic rate is a feature of the unstimulated toxoplasma-immune macrophage, but this change in rate alone does not correlate with the cell's ability to inhibit toxoplasma. In addition, we observed that enhanced pinocytosis as seen in the elicited macrophage was not a requirement for inhibition of toxoplasma multiplication. 相似文献
7.
Wells GD Plyley M Thomas S Goodman L Duffin J 《European journal of applied physiology》2005,94(5-6):527-540
The efficiency of the respiratory system presents significant limitations on the bodys ability to perform exercise due to the effects of the increased work of breathing, respiratory muscle fatigue, and dyspnoea. Respiratory muscle training is an intervention that may be able to address these limitations, but the impact of respiratory muscle training on exercise performance remains controversial. Therefore, in this study we evaluated the effects of a 12-week (10 sessions week–1) concurrent inspiratory and expiratory muscle training (CRMT) program in 34 adolescent competitive swimmers. The CRMT program consisted of 6 weeks during which the experimental group (E, n=17) performed CRMT and the sham group (S, n=17) performed sham CRMT, followed by 6 weeks when the E and S groups performed CRMT of differing intensities. CRMT training resulted in a significant improvement in forced inspiratory volume in 1 s (FIV1.0) (P=0.050) and forced expiratory volume in 1 s (FEV1.0) (P=0.045) in the E group, which exceeded the S groups results. Significant improvements in pulmonary function, breathing power, and chemoreflex ventilation threshold were observed in both groups, and there was a trend toward an improvement in swimming critical speed after 12 weeks of training (P=0.08). We concluded that although swim training results in attenuation of the ventilatory response to hypercapnia and in improvements in pulmonary function and sustainable breathing power, supplemental respiratory muscle training has no additional effect except on dynamic pulmonary function variables. 相似文献
8.
9.
R. Beckerhoff R. Wilkinson J. A. Luetscher W. Vetter W. Siegenthaler G. W. Nokes 《Journal of molecular medicine (Berlin, Germany)》1972,50(14):702-705
Zusammenfassung Ein Radioimmunoassay für Angiotensin I und seine Anwendung für die Messung der Reninkonzentration im Plasma werden beschrieben. Die zur Herstellung von Angiotensinantikörpern und radioaktiv markiertem Angiotensin sowie zur Trennung von gebundenem und freiem Hormon benutzten Verfahren werden mitgeteilt. Die Empfindlichkeit der Methode erlaubt den Nachweis von zwanzig Pikogramm Angiotensin I.Zur Messung der Reninkonzentration wurde substratfreies Plasma mit Schafsubstrat im Überschuß versetzt und in Anwesenheit von Inhibitoren von converting enzyme und Angiotensinasen bei 37°C inkubiert. Das gebildete Angiotensin wurde in 20 µl des proteinfreien Inkubationsgemisches bestimmt. Die initiale Geschwindigkeit der Angiotensinbildung wurde zur Berechnung der Reninkonzentration herangezogen. Als eine Einheit wurde die Reninmenge definiert, die ein Nanogramm Angiotensin I pro Stunde Inkubation bildet.Normalwerte unter kontrollierter natriumreicher und natriumarmer Diät wurden ermittelt.Die Empfindlichkeit der Methode erlaubt die Messung der Reninkonzentration im Plasma von Patienten mit primärem Aldosteronismus.Mit Unterstützung der Deutschen Forschungsgemeinschaft. 相似文献
10.
中国狂犬病毒疫苗株(5aG)糖蛋白基因在痘苗病毒中的表达及免疫效果观察 总被引:1,自引:0,他引:1
将克隆到的中国狂犬病毒疫苗株(5aG)的糖蛋白基因重组到痘苗病毒TK区,并在痘苗病毒P11启动子的控制下,构建了狂犬-痘苗重组病毒(VVaG)。经间接免疫荧光和Western免疫印染证明,重组病毒VVaG能良好地表达狂犬病毒糖蛋白,其分子量约为6600。用VVaG免疫小鼠,7d便可诱生较高的狂犬病毒中和抗体,21d达4169,并能100%保护狂犬病毒本毒株和国际标准攻击毒(CVS)的致死量攻击。 相似文献