全文获取类型
收费全文 | 141859篇 |
免费 | 7023篇 |
国内免费 | 411篇 |
专业分类
耳鼻咽喉 | 1930篇 |
儿科学 | 4469篇 |
妇产科学 | 3496篇 |
基础医学 | 19954篇 |
口腔科学 | 5629篇 |
临床医学 | 9861篇 |
内科学 | 31095篇 |
皮肤病学 | 3835篇 |
神经病学 | 11482篇 |
特种医学 | 3379篇 |
外国民族医学 | 11篇 |
外科学 | 17186篇 |
综合类 | 1116篇 |
一般理论 | 48篇 |
预防医学 | 15613篇 |
眼科学 | 2858篇 |
药学 | 10381篇 |
4篇 | |
中国医学 | 692篇 |
肿瘤学 | 6254篇 |
出版年
2023年 | 910篇 |
2022年 | 1075篇 |
2021年 | 3170篇 |
2020年 | 1869篇 |
2019年 | 3167篇 |
2018年 | 4832篇 |
2017年 | 3107篇 |
2016年 | 3025篇 |
2015年 | 3580篇 |
2014年 | 4148篇 |
2013年 | 5937篇 |
2012年 | 9558篇 |
2011年 | 9888篇 |
2010年 | 5159篇 |
2009年 | 3907篇 |
2008年 | 7710篇 |
2007年 | 8018篇 |
2006年 | 7613篇 |
2005年 | 7455篇 |
2004年 | 6863篇 |
2003年 | 6391篇 |
2002年 | 5916篇 |
2001年 | 4072篇 |
2000年 | 4338篇 |
1999年 | 3474篇 |
1998年 | 790篇 |
1997年 | 538篇 |
1996年 | 529篇 |
1995年 | 459篇 |
1992年 | 1677篇 |
1991年 | 1534篇 |
1990年 | 1442篇 |
1989年 | 1290篇 |
1988年 | 1210篇 |
1987年 | 1148篇 |
1986年 | 1061篇 |
1985年 | 1015篇 |
1984年 | 791篇 |
1983年 | 620篇 |
1979年 | 768篇 |
1978年 | 484篇 |
1975年 | 455篇 |
1974年 | 650篇 |
1973年 | 629篇 |
1972年 | 527篇 |
1971年 | 488篇 |
1970年 | 577篇 |
1969年 | 516篇 |
1968年 | 476篇 |
1967年 | 454篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
S R Torres C B Peixoto D M Caldas E B Silva F A C Magalh?es M Uzeda M Nucci 《Medical mycology》2003,41(5):411-415
In order to investigate the clinical factors that might influence the diversity and the degree of Candida species carriage in saliva, we conducted a cross-sectional study with 133 patients with complaints of xerostomia. Anamnesis, oral examination and collection of chewing-stimulated whole saliva were performed. The samples of saliva were kept refrigerated until they were plated onto CHROMagar Candida; cfu were counted and Candida species were identified by standard methods. There was a high prevalence of mixed Candida colonization. No relationship was found between total Candida cfu counts and variables like gender, age, place of origin, underlying diseases, exposure to medications (except antibiotics), daily habits and salivary flow rates. Oral candidiasis, antibiotic exposure and dental prosthesis wearing were associated with relatively high Candida counts in saliva. Low salivary flow rates predisposed to intense colonization by C. albicans and C. parapsilosis. 相似文献
993.
Wolfram syndrome (WS) is an autosomal recessive neurodegenerative disorder characterised by early onset diabetes mellitus and progressive optic atrophy, as well as other clinical features such as deafness, diabetes insipida, renal tract abnormalities and diverse psychiatric illnesses. A gene responsible for WS was identified in 4p16.1 (WFS1). It encodes a putative 890 amino acid transmembrane protein expressed in a wide spectrum of tissues. Recently, a new locus for WS has been located on 4q22-24, providing additional evidence for the genetic heterogeneity of this syndrome. We have studied the presence of WFS1 variants in three groups of individuals: patients with diabetes mellitus, patients with deafness and patients with both conditions. A fourth group of healthy subjects was used as control. We have identified a total of 18 nucleotide changes in the WFS1 gene: three mutations and 15 polymorphisms. Six of these changes were previously undescribed. Four of the 15 polymorphisms studied among the patients group present statistical differences in the allelic and genotypic distribution when comparing affected vs control groups. 相似文献
994.
Płodziszewska M Chorostowska J Polubiec-Kownacka M Jaroń B Lenarcik D Marzinek M Szopiński J Wiatr E Załeska J Zych J Skopińska-Rózewska E Rowińska-Zakrzewska E 《Pneumonologia i alergologia polska》2000,68(11-12):557-565
The aim of this study was to assess how the extent of the number and percentage of lymphocytes in BALF and also the CD4 to CD8 ratio can help to predict the short outcome in sarcoidosis. Material consisted of 74 patients, 39 men and 35 women in the age from 23 to 58 years. 11 patients had chest lesions in stage I, 43 in stage II and 20 in stage III. Clinical markers of activity (fever, erythema nodosum) were present in 22 cases. Extrathoracic lesion were present in 31 and abnormal pulmonary function in 30. In all patients BAL was done before treatment and lymphocyte count, percentage and CD4/CD8 ratio was calculated. 50 patients were treated with corticosteroids and 24 were observed without treatment. After 6-12 month of observation regression of sarcoid lesions was observed in 46 of 50 patients treated with corticosteroids and in 17 out of 24 patients observed without treatment. There were no differences in lymphocyte count and percentage in BALF and in the short term outcome between group treated with corticosteroids and without treatment. The patients in whom regression of lesions was observed have however significantly higher CD4/CD8 ratio than others. 相似文献
995.
A Parasyn R M Hanson MBBCh MPH MRACMA FRACP FACEM J K Peat M De Silva 《Journal of digital imaging》1998,11(1):45-49
Picture Archiving and Communication Systems (PACS) make possible the viewing of radiographic images on computer workstations located where clinical care is delivered. By the nature of their work this feature is particularly useful for emergency physicians who view radiographic studies for information and use them to explain results to patients and their families. However, the high cost of PACS diagnostic workstations with fuller functionality places limits on the number of and therefore the accessibility to workstations in the emergency department. This study was undertaken to establish how well less expensive personal computer-based workstations would work to support these needs of emergency physicians. The study compared the outcome of observations by 5 emergency physicians on a series of radiographic studies containing subtle abnormalities displayed on both a PACS diagnostic workstation and on a PC-based workstation. The 73 digitized radiographic studies were randomly arranged on both types of workstation over four separate viewing sessions for each emergency physician. There was no statistical difference between a PACS diagnostic workstation and a PC-based workstation in this trial. The mean correct ratings were 59% on the PACS diagnostic workstations and 61% on the PC-based workstations. These findings also emphasize the need for prompt reporting by a radiologist. 相似文献
996.
997.
Although it is well known that cyclic production of sex hormones is essential to establish reproductive function and female characteristics, distant impacts of the activity of the female endocrine system result from a concert of delicate mechanisms. Estrogen is rather an instrument than a conductor in this physiological orchestra of the female. Thus, controversies in the explanation of results from studies on hormone replacement therapy (HRT) and cardiovascular disease (CVD) prevention might be eliminated, if we analyse not only the role of estrogen but a broader spectrum of factors leading to CVD. Authors would like to hypothesize that haemorheological changes in women around menopause, such as increased blood and plasma viscosity, haematocrit and fibrinogen, are largely responsible for the increased mortality in the post-menopausal life period. We believe that a cyclic withdrawal bleeding establishes a more favourable haemorheological condition, thus, sequentially administered estrogen might be protective in post-menopausal women. Nevertheless, other factors, that decrease blood viscosity, such as daily exercise, intake of ample amount of fluids as well as ideal nutrition, are equally important. We are confident that sequential HRT, as well as healthy life style and risk prevention programmes have their proper place in the management of this issue. 相似文献
998.
González C Nájera O Cortés E Toledo G López L Betancourt M Ortiz R 《Teratogenesis, carcinogenesis, and mutagenesis》2002,22(2):147-158
Infectious disease and malnutrition in children are public health problems in developing countries. Malnutrition is associated with higher levels of DNA damage, and this increased damage could be due to different factors, including the possibility that cells from malnourished children could be more susceptible to environmental damage. The aim of the present study was to evaluate the susceptibility of lymphocytes from malnourished children to DNA damage induced by antibiotics by using the comet assay. The same group of malnourished infected children were studied before and after a treatment period, and compared to a group of well-nourished infected children. Results showed that before and after drug treatment, tail length migration was two times greater in malnourished than in well-nourished children. The proportion of cells with high damage was also increased in malnourished children. Additionally in well-nourished and malnourished children, a cell subpopulation (non-damaged cells) more resistant to DNA damage induced by antibiotics was observed; this was more prevalent in the well-nourished children. Meanwhile, in malnourished children, a cell population seems to be more susceptible and reaches higher levels of DNA damage. This might help explain the impaired immune response observed in malnourished children. The increased DNA migration and the increased proportion of cells with higher levels of damage seem to indicate that malnourished children are more susceptible to DNA damage induced by drugs. 相似文献
999.
Calbindin D28k-containing non-pyramidal cells were found in all layers and subfields of the hippocampus, with the highest frequency in stratum radiatum of the CA1-CA3 subfields. A large number of these neurons had a vertically oriented dendritic tree, often restricted to to stratum radiatum. In stratum oriens and near to the border of strata radiatum and lacunosum moleculare cells with horizontally running dendrites were also found. Multipolar cells were most common in stratum radiatum of the CA3 region. The GABAergic nature of the calbindin D28k-containing non-pyramidal cells was studied using the "mirror" technique. Adjacent thick sections were immunostained for calbindin D28k and GABA, and halved neurons were identified on the common surfaces. The majority of calbindin D28k-containing non-pyramidal cells were shown to be GABAergic. The GABA-negative calbindin cells were found in relatively large numbers in stratum oriens of the CA1-CA3 region, and occasionally in strata radiatum and pyramidale of CA2, and in stratum radiatum of the CA3c region near to the border of the dentate hilus. However, even in these cells a weak immunostaining, only slightly but consistently above background level, was always observed. Earlier studies have demonstrated that the somata of GABAergic neurons with distant projections may contain a level of GABA that is below the detection threshold of immunocytochemistry. Here we provide direct evidence that the calbindin-containing non-pyramidal cells were among those projecting to the medial septum. Following horseradish peroxidase injections into the medial septum 80% of the retrogradely labelled non-pyramidal cells were found to be immunoreactive for calbindin D28k, and 20% contained neuropeptide Y. These results suggest that the calbindin D28k-containing and apparently GABA-immunonegative non-pyramidal cells in stratum oriens of the CA1-CA3 regions may also be GABAergic, but have a distant projection, that is, to the medial septum. 相似文献
1000.
B. C. J. Hamel R. Happle P. M. Steylen L. A. A. Kolle J. H. Schuurmans Stekhoven J. G. Nijhuis R. Rauskolb I. Anton-Lamprecht 《American journal of medical genetics. Part A》1992,44(6):824-826
Restrictive dermopathy is a rare autosomal recessive lethal skin dysplasia. It has been assumed that the characteristic morphologic abnormalities should allow a reliable prenatal diagnosis on fetal skin biopsies at about 20 weeks pregnancy. We report on a false-negative prenatal diagnosis. © 1992 Wiley-Liss, Inc. 相似文献