全文获取类型
收费全文 | 2244篇 |
免费 | 273篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 28篇 |
儿科学 | 70篇 |
妇产科学 | 36篇 |
基础医学 | 399篇 |
口腔科学 | 108篇 |
临床医学 | 284篇 |
内科学 | 505篇 |
皮肤病学 | 45篇 |
神经病学 | 203篇 |
特种医学 | 73篇 |
外科学 | 292篇 |
综合类 | 9篇 |
一般理论 | 3篇 |
预防医学 | 188篇 |
眼科学 | 37篇 |
药学 | 145篇 |
中国医学 | 2篇 |
肿瘤学 | 93篇 |
出版年
2023年 | 37篇 |
2021年 | 38篇 |
2020年 | 45篇 |
2019年 | 48篇 |
2018年 | 82篇 |
2017年 | 88篇 |
2016年 | 90篇 |
2015年 | 106篇 |
2014年 | 100篇 |
2013年 | 211篇 |
2012年 | 153篇 |
2011年 | 138篇 |
2010年 | 105篇 |
2009年 | 48篇 |
2008年 | 84篇 |
2007年 | 91篇 |
2006年 | 94篇 |
2005年 | 79篇 |
2004年 | 107篇 |
2003年 | 77篇 |
2002年 | 78篇 |
2001年 | 28篇 |
2000年 | 10篇 |
1999年 | 15篇 |
1998年 | 16篇 |
1997年 | 12篇 |
1996年 | 19篇 |
1995年 | 21篇 |
1994年 | 10篇 |
1992年 | 17篇 |
1991年 | 15篇 |
1989年 | 11篇 |
1988年 | 14篇 |
1987年 | 11篇 |
1986年 | 21篇 |
1985年 | 14篇 |
1984年 | 22篇 |
1982年 | 17篇 |
1981年 | 10篇 |
1980年 | 10篇 |
1979年 | 13篇 |
1978年 | 10篇 |
1977年 | 10篇 |
1976年 | 10篇 |
1974年 | 10篇 |
1955年 | 38篇 |
1954年 | 88篇 |
1949年 | 20篇 |
1948年 | 17篇 |
1943年 | 11篇 |
排序方式: 共有2520条查询结果,搜索用时 15 毫秒
1.
2.
3.
The activity of a rheumatic disease can be influenced by pregnancy and puerperium. Prospective studies have shown an improvement in joint involvement in rheumatoid arthritis in two thirds to three quarters of pregnancies. After birth, an exacerbation is common. In spondylarthropathies there is no relevant change in disease activity. The fetal outcome is not impaired in patients with rheumatoid arthritis and inflammatory spondylarthropathies. Every pregnancy in women with a rheumatic disease should be considered as high-risk, and such pregnancies require close collaboration between rheumatologists and obstetricians. 相似文献
4.
5.
Muscle cell leakage due to long distance training 总被引:3,自引:0,他引:3
K. NØrregaard Hansen J. Bjerre-Knudsen U. Brodthagen R. Jordal P. -E. Paulev 《European journal of applied physiology》1982,48(2):177-188
Summary Abnormal myoglobinemia (above 77 g/1) and free hemoglobin in plasma were found in 16 runners and in nine non runners immediately following distance running. The same abnormalities were found in six elite rowers following rowing. In parallel with the rise in myoglobin and free hemoglobin a rise was found in serum concentrations of cellular enzymes (LDH, CK, ASAT, alkaline phosphatase) and of various metabolites. We found no proteinuria nor casts in the urine. Non runners had a higher rise in serum myoglobin than runners. Competitive running caused a rise in the serum concentration of the heart specific fraction of creatine kinase in seven of the nine (healthy) elite runners. The abnormal findings are only explainable on the basis of leakage of proteins from muscle cells to the circulation in otherwise healthy, well trained persons. Myoglobinemia and a transient rhabdomyolysis is a common phenomenon in long distance running, but evidently also occurs in distance rowing. Three months of running training prevented most of the muscle damage from relaxed jogging in the nine previous non runners. Neither the observed myoglobinemia nor the hemoglobinemia resulted in any significant loss of iron in the urine.Supported by IdrÆttens Forskningsråd, Dansk IdrÆtsforbund 相似文献
6.
Summary Major changes occur in the serum level of several hormones during 5 days of heavy and continuous physical activities, with less than a total of 2 h of sleep. The present investigation was designed to evaluate the importance of caloric deficiency, energy requirement being about 8,000–10,000 kcal/24 h. A comparison between well fed subjects and those with food deprivation revealed significantly higher levels of (T3) triiodothyronin, insulin and thyroid stimulating hormone (TSH) in the well-fed subjects, who also had lower levels of growth hormone (hGH) and cortisol, whereas no difference was found between the two groups for thyroxin (T4). Increased levels were found for T3 and T4 in both groups during the first day of activity, with a concomitant decrease in TSH and a subsequent decrease of T4 during the next 2 days. T3 decreased only in the low-calory group whereas increased levels were found in the iso-calory group throughout the course. The resting levels of insulin decreased during the course in the low-calory group whereas it increased in the iso-calory group. High levels were maintained throughout the course for hGH. Cortisol showed high levels just before the start of the course and then decreased from day 2 to day 4. No difference was found between the morning and evening levels for cortisol, indicating disappearance of the circadian rhythm. The present investigation has shown that energy deficiency during prolonged physical strain is responsible for the decreased serum levels of T3 and insulin and may contribute to the decrease in TSH and the increase in hGH and cortisol. 相似文献
7.
Novel mouse model of chronic Pseudomonas aeruginosa lung infection mimicking cystic fibrosis
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)
Hoffmann N Rasmussen TB Jensen PØ Stub C Hentzer M Molin S Ciofu O Givskov M Johansen HK Høiby N 《Infection and immunity》2005,73(4):2504-2514
Pseudomonas aeruginosa causes a chronic infection in the lungs of cystic fibrosis (CF) patients by establishing an alginate-containing biofilm. The infection has been studied in several animal models; however, most of the models required artificial embedding of the bacteria. We present here a new pulmonary mouse model without artificial embedding. The model is based on a stable mucoid CF sputum isolate (NH57388A) with hyperproduction of alginate due to a deletion in mucA and functional N-acylhomoserine lactone (AHL)-based quorum-sensing systems. Chronic lung infection could be established in both CF mice (Cftr(tmlUnc-/-)) and BALB/c mice, as reflected by the detection of a high number of P. aeruginosa organisms in the lung homogenates at 7 days postinfection and alginate biofilms, surrounded by polymorphonuclear leukocytes in the alveoli. In comparison, both an AHL-producing nonmucoid revertant (NH57388C) from the mucoid isolate (NH57388A) and a nonmucoid isolate (NH57388B) deficient in AHL were almost cleared from the lungs of the mice. This model, in which P. aeruginosa is protected against the defense system of the lung by alginate, is similar to the clinical situation. Therefore, the mouse model provides an improved method for evaluating the interaction between mucoid P. aeruginosa, the host, and antibacterial therapy. 相似文献
8.
P. Magnus A. -L. BØrresen P. K. Opstad J. F. Bugge K. Berg 《European journal of applied physiology》1984,53(1):21-24
Summary Effects of four days of intense physical activity on serum concentrations of total triglycerides, total cholesterol and apolipoproteins A-I, A-II, and B were studied in 35 well-trained young men. Serum total triglyceride levels decreased to 70% of baseline levels after 24 h, and fell further to 50% of baseline levels after 4 days. Serum levels of total cholesterol fell steadily to about 80% of baseline levels on the 4th day. Apo-B levels fell to 85% of baseline levels after 24 h, and remained at that level. Apo A-I fell to about 90%, and apo A-II to about 80% of baseline levels, causing a significant increase in the ratio of apo A-I to apo A-II. The intraindividual changes in apo B were positively correlated to changes in cholesterol during the first day (r=0.60). The changes in apo A-I and apo A-II had no significant correlation with changes in total cholesterol or triglycerides, or with one another, suggesting that apo A-I and apo A-II are metabolized independently during conditions of hard physical exercise. 相似文献
9.
Summary Resting pulmonary plasma and blood volumes (PPV and PBV), interventricular circulation time (IVCT), cardiac and stroke index (CI and SI), heart rate (HR), total plasma and blood volumes (PV and BV) were determined in athletes (two male groups representing different types of sport activities, and one female group) and compared with those of non-athletes (one male and one female group).In addition to high maximal aerobic power, the athletes were characterized by greater SI, BV and PV and lower resting HR than non-athletes. PPV and PBV were significantly larger and IVCT significantly longer in the trained than in the untrained groups, probably reflecting an improved capacity of the pulmonary circulation. PPV as per cent of PV was almost equal in all the groups, indicating the same distribution of plasma between the pulmonary and systemic circulation. The data also indicate that total blood volume is an important determinant of the magnitude of the pulmonary vascular bed. The increased volume of flowing blood and increased stroke volume in athletes probably allows for a reduction in flow velocity and thereby a reduction in kinetic energy. 相似文献
10.
Characterization of Escherichia coli O157:H7 and other Shiga toxin-producing E. coli serotypes isolated from sheep. 总被引:4,自引:0,他引:4
下载免费PDF全文
![点击此处可从《Journal of clinical microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
The isolation and characterization of Escherichia coli O157:H7 and non-O157 Shiga toxin-producing E. coli (STEC) strains from sheep are described. One flock was investigated for E. coli O157:H7 over a 16-month period that spanned two summer and two autumn seasons. Variation in the occurrence of E. coli O157:H7-positive sheep was observed, with animals being culture positive only in the summer months but not in the spring, autumn, or winter. E. coli O157:H7 isolates were distinguished by pulsed-field gel electrophoresis (PFGE) of chromosomal DNA and toxin gene restriction fragment length polymorphism (RFLP) analysis. Ten PFGE patterns and five RFLP patterns, identified among the isolates, showed that multiple E. coli O157:H7 strains were isolated from one flock, that a single animal simultaneously shed multiple E. coli O157:H7 strains, and that the strains shed by individuals changed over time. E. coli O157:H7 was isolated only by selective enrichment culture off 10 g of ovine feces. In contrast, strains of eight STEC serotypes other than O157:H7 were cultured from feces of sheep from a separate flock without enrichment. The predominant non-O157 STEC serotype found was O91:NM (NM indicates nonmotile), and others included O128:NM, O88:NM, O6:H49, and O5:NM. Irrespective of serotype, 98% of the ovine STEC isolates possessed various combinations of the virulence-associated genes for Shiga toxin(s) and the attaching-and-effacing lesion (stx1, stx2, and eae), suggesting their potential for human pathogenicity. The most common toxin-eae genotype was positive for stx1, stx2, and eae. A Vero cell cytotoxicity assay demonstrated that 90% of the representative STEC isolates tested expressed the toxin gene. The report demonstrates that sheep transiently shed a variety of STEC strains, including E. coli O157:H7, that have potential as human pathogens. 相似文献