全文获取类型
收费全文 | 2107篇 |
免费 | 120篇 |
国内免费 | 39篇 |
学科分类
医药卫生 | 2266篇 |
出版年
2022年 | 11篇 |
2021年 | 21篇 |
2020年 | 23篇 |
2019年 | 22篇 |
2018年 | 34篇 |
2017年 | 31篇 |
2016年 | 40篇 |
2015年 | 41篇 |
2014年 | 49篇 |
2013年 | 70篇 |
2012年 | 84篇 |
2011年 | 104篇 |
2010年 | 90篇 |
2009年 | 79篇 |
2008年 | 79篇 |
2007年 | 97篇 |
2006年 | 96篇 |
2005年 | 92篇 |
2004年 | 68篇 |
2003年 | 59篇 |
2002年 | 63篇 |
2001年 | 57篇 |
2000年 | 33篇 |
1999年 | 47篇 |
1998年 | 65篇 |
1997年 | 56篇 |
1996年 | 57篇 |
1995年 | 45篇 |
1994年 | 46篇 |
1993年 | 32篇 |
1992年 | 51篇 |
1991年 | 45篇 |
1990年 | 30篇 |
1989年 | 46篇 |
1988年 | 45篇 |
1987年 | 33篇 |
1986年 | 36篇 |
1985年 | 21篇 |
1984年 | 16篇 |
1983年 | 17篇 |
1982年 | 15篇 |
1980年 | 16篇 |
1979年 | 20篇 |
1978年 | 15篇 |
1977年 | 13篇 |
1976年 | 13篇 |
1975年 | 12篇 |
1971年 | 11篇 |
1969年 | 10篇 |
1934年 | 13篇 |
排序方式: 共有2266条查询结果,搜索用时 238 毫秒
1.
D J Brooks J S Gibbs P Sharp S Herold D R Turton S K Luthra E M Kohner S R Bloom T Jones 《Journal of cerebral blood flow and metabolism》1986,6(2):240-244
Regional cerebral [11C]3-O-methyl-D-glucose ([11C]MeG) uptake kinetics have been measured in five insulin-dependent diabetic patients and four normal controls using positron emission tomography (PET). Concomitant measurement of regional cerebral blood volume and CBF enabled corrections for the presence of intravascular [11C]MeG signal in cerebral regions of interest to be carried out, and regional cerebral [11C]MeG unidirectional extraction fractions to be computed. Four of the five diabetic subjects were studied with their fasting plasma glucose level clamped at a normoglycaemic level (4 mM), and four were studied at hyperglycaemic plasma glucose levels (mean 13 mM). The four diabetic subjects whose fasting plasma glucose levels were clamped at a normoglycaemic level of 4 mM had mean fasting whole-brain, cortical, and white matter [11C]MeG extraction fractions of 15, 15, and 16%, respectively, values similar to those found for the four normal controls (whole brain, 14%; cortex, 13%; white matter, 17%). Mean regional cerebral [11C]MeG extraction fractions were significantly reduced in diabetic subjects during hyperglycaemia whether their plasma insulin levels were undetectable or whether they were raised by continuous intravenous insulin infusion. Such a reduction in [11C]MeG extraction under hyperglycaemic conditions can be explained entirely in terms of increased competition between [11C]MeG and D-glucose for the passive facilitated transport carrier system for hexoses across the blood-brain barrier (BBB). It is concluded that the number and affinity of D-glucose carriers present in the BBB are within normal limits in treated insulin-dependent diabetic subjects. In addition, insulin appears to have no effect on the transport of D-glucose across the BBB. 相似文献
2.
3.
A Herold 《Der Chirurg》2006,77(8):737-47; quiz 748
Hemorrhoidal disease is one of the most frequent disorders in western countries. The aim of individual therapy is freedom from symptoms achieved by normalisation of anatomy and physiology. Treatment is orientated to the stage of disease: haemorrhoids 1 are treated conservatively. In addition to high-fibre diet, sclerotherapy is used. Haemorrhoids 2 prolapse during defecation and return spontaneously. First-line treatment is rubber band ligation. Haemorrhoids 3 that prolapse during defecation have to be digitally reduced, and the majority need surgery. For segmental disorders, haemorrhoidectomy according to Milligan-Morgan or Ferguson is recommended. In circular disease, Stapler hemorrhoidopexy is now the procedure of choice. Using a therapeutic regime according to the hemorrhoidal disease classification offers high healing rates and low rates of complications and recurrence. 相似文献
4.
Kuen Werthemann A. Dietrich Sponholz Rodewald Druckrey L. Herold Fauvet Merten K. Tietze Carl Clauberg H. Beck Sponholz Böhmig 《Journal of cancer research and clinical oncology》1940,49(1):60-71
Ohne Zusammenfassung 相似文献
5.
6.
The authors investigated whether graduating students' specialty choices were influenced by favorable faculty evaluations and mini-Board scores during their third-year clerkships, and if so, whether the influences were gender-specific. Data were collected from a total of 53 students in two classes, 1988-89 and 1988-90. Univariate and multivariate tests were performed, and the results were analyzed between each class group and between genders in both groups. These results also were compared with information about the students gathered before they matriculated. In general, the results showed a gender-specific correlation: for each rotation where the women's faculty evaluations were significantly higher than the men's, the women subsequently outnumbered the men in choosing that rotation's specialty. Conversely, for each rotation where the men's mini-Board scores were significantly higher than the women's, the men outnumbered the women in choosing that rotation's specialty. The most notable difference was in pediatrics: 8% of the women had indicated an interest in that specialty on the prematriculation questionnaire, while almost one-third of the women in the classes of 1990 and 1991 chose pediatrics residencies. These findings suggest that the favorable scores and evaluations may be one of the influences for students' specialty choices, and that their influence may be gender-specific. 相似文献
7.
8.
Arianne C Lim Kitty WM Bloemenkamp Kees Boer Johannes J Duvekot Jan Jaap HM Erwich Tom HM Hasaart Pieter Hummel Ben WJ Mol Jos PM Offermans Charlotte M van Oirschot Job G Santema Hubertina CJ Scheepers Willem A Schöls Frank PHA Vandenbussche Maurice GAJ Wouters Hein W Bruinse 《BMC pregnancy and childbirth》2007,7(1):1-6
Background
Adequate vitamin D concentrations during pregnancy are necessary to neonatal calcium homeostasis, bone maturation and mineralization. The aim of study is to evaluate serum vitamin D concentrations in mothers and their newborns and effect of vitamin D deficiency on pregnancy outcomes.Methods
552 pregnant women were recruited from Tehran University educating hospitals in the winter of 2002. Maternal and cord blood samples were taken at delivery. The serum was assayed for 25-hydroxyvitamin D3, calcium, phosphorus and parathyroid hormone.Results
The prevalence of vitamin D deficiency in maternal and cord blood samples were 66.8% and 93.3%, respectively (<35 nmol/l). There was significant correlation between maternal and cord blood serum concentrations of vitamin D. In mothers with vitamin D deficiency, cord blood vitamin D concentrations was lower than those from normal mothers (P = .001). Also, a significant direct correlation was seen between maternal vitamin D intake and weight gain during pregnancy.Conclusion
Consideration to adequate calcium and vitamin D intake during pregnancy is essential. Furthermore, we think it is necessary to reconsider the recommendation for vitamin D supplementation for women during pregnancy. 相似文献9.
Pneumonia is one of the leading causes of morbidity, hospitalization, and mortality in both industrialized and developing countries. In particular, pulmonary infections acquired in the community, and pneumonias arising in the hospital setting, represent a major medical and economic problem and thus a continuous challenge to health care. For the radiologist, it is important to understand that community-acquired pneumonia (CAP) and nosocomial pneumonia (NP) share a number of characteristics, but should, in many respects be regarded as separate entities. CAP and NP arise in different populations, host different spectra of causative pathogens, and pose different challenges to both the clinician and the radiologist. CAP is generally seen in outpatients, is most frequently caused by Streptococcus pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae, and Chlamydia, and its radiologic diagnosis is relatively straightforward. NP, in contrast, develops in the hospital setting, is commonly caused by gram-negative bacteria, and may generate substantial problems for the radiologist. Overall, both for CAP and NP, imaging is an integral component of the diagnosis, important for classification and differential diagnosis, and helpful for follow-up. 相似文献
10.