首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1501篇
  免费   117篇
  国内免费   21篇
耳鼻咽喉   7篇
儿科学   26篇
妇产科学   18篇
基础医学   177篇
口腔科学   21篇
临床医学   158篇
内科学   236篇
皮肤病学   37篇
神经病学   54篇
特种医学   112篇
外科学   291篇
综合类   16篇
一般理论   1篇
预防医学   78篇
眼科学   38篇
药学   76篇
中国医学   2篇
肿瘤学   291篇
  2023年   8篇
  2022年   6篇
  2021年   9篇
  2020年   14篇
  2019年   18篇
  2018年   23篇
  2017年   27篇
  2016年   28篇
  2015年   32篇
  2014年   27篇
  2013年   43篇
  2012年   67篇
  2011年   74篇
  2010年   40篇
  2009年   42篇
  2008年   66篇
  2007年   88篇
  2006年   61篇
  2005年   73篇
  2004年   45篇
  2003年   61篇
  2002年   59篇
  2001年   48篇
  2000年   62篇
  1999年   60篇
  1998年   38篇
  1997年   35篇
  1996年   27篇
  1995年   21篇
  1994年   14篇
  1993年   20篇
  1992年   36篇
  1991年   35篇
  1990年   42篇
  1989年   32篇
  1988年   24篇
  1987年   35篇
  1986年   19篇
  1985年   26篇
  1984年   16篇
  1983年   18篇
  1982年   13篇
  1981年   8篇
  1979年   6篇
  1975年   6篇
  1974年   6篇
  1973年   7篇
  1972年   7篇
  1970年   5篇
  1966年   10篇
排序方式: 共有1639条查询结果,搜索用时 15 毫秒
81.
BACKGROUND: The majority of hemochromatosis patients are homozygous for the HFE-C282Y mutation. However, less than half of C282Y homozygous subjects identified by population screening studies actually develop the disease. The cytokine TNF-alpha is implicated in the regulation of iron metabolism at different levels. Our aim was to study the role of TNF-alpha and its promoter polymorphisms in the phenotypic expression of hemochromatosis in individuals with and without the C282Y mutation. METHODS: We studied 4 groups of 10 subjects each: (1) C282Y homozygotes without clinical hemochromatosis; (2) C282Y homozygotes with hemochromatosis; (3) secondary hemochromatosis (without C282Y mutation); and (4) controls. Groups were age-matched and sex-matched. Peripheral blood mononuclear cells (PBMC) were stimulated with lipopolysaccharide (LPS) and the release of TNF-alpha was measured. Additionally, the G/A polymorphisms at position -238 and -308 of the TNF-alpha, gene were determined by PCR and RFLP analysis in 178 hemochromatosis patients and 41 controls. RESULTS: TNF-alpha production from PBMC at 8 and 24 h after increasing concentrations of LPS stimulation were similar in the four groups. The prevalence of TNF-alpha polymorphisms was similar in patients and controls. The prevalences of cirrhosis, siderosis, median s-ferritin and median ALT values were similar in patients with and without the TNF-alpha polymorphisms. CONCLUSIONS: Neither TNF-alpha, released from PBMC nor the presence of TNF-alpha polymorphisms seem to be associated with disease manifestation in hemochromatosis.  相似文献   
82.
Predictors of 'patient satisfaction' with hospitalization at a specialized cancer hospital in Norway are examined in this study. Two weeks after their last hospitalization, 2021 consecutive cancer patients were invited to rate their satisfaction with hospitalization, quality of life, anxiety and depression. Compliance rate was 72% (n = 1453). Cut-off levels separating dissatisfied from satisfied patients were defined. It was found that 92% of the patients were satisfied with their stay in hospital, independent of cancer type and number of previous admissions. Performance of nurses and physicians, level of information perceived, outcome of health status, reception at the hospital and anxiety independently predicted 'patient satisfaction'. The model explained 35% of the variance with an area under the curve of 0.76 of the Receiver Operator Curve. Cancer patients' satisfaction with their hospital stay was high, and predicted by four independently predictive variables related to the performance of caregivers. These suggest areas for further improvement in the healthcare service.  相似文献   
83.
84.
BACKGROUND: The aim of this study was to compare the scorings of anxiety and depression assessed by the Hospital Anxiety and Depression Scale (HADS-A [Anxiety] and HADS-D [Depression]) with the scorings on the eight subscales of Short Form 36 (SF-36) and the Physical (PCS) and Mental Component Summary (MCS) assessed by the same patients. METHOD: In a cross-sectional study 736 long-term survivors after treatment for testicular cancer (TC) completed HADS and SF-36. Pearson's correlation coefficients were calculated on item and scale level to assess the associations between the HADS and the SF-36 scales and, in particular, between HADS and PCS and MCS, respectively. Independent predictors for PCS and MCS were identified by linear regression analysis. RESULTS: HADS-A and HADS-D were significantly associated with the SF-36 summary scales. HADS-A explained 5% of the variance of PCS and 49% of the variance of MCS. The comparable figures for HADS-D were 10% and 45%, respectively. In the multivariate analysis the HADS-D scoring independently predicted the level of PCS together with the patients' educational level, long-lasting working disability and age (variance: 30%). Both HADS-D and HADS-A remained independent parameters for MCS (variance: 58%) together with the patient's civil status. HADS-D item D4 ("slowed down") was similarly associated with both PCS and MCS. CONCLUSION: In univariate analyses HADS-D and HADS-A were statistically associated with PCS and MCS. The highest r values were observed for the associations between HADS and MCS, in particular between HADS-A and MCS. In the multivariate analyses HADS-D, but not HADS-A, contributed to PCS, whereas both HADS-A and HADS-D were associated with MCS. This pattern of different predictions of the summary scales of SF-36 supports a clinical practice that anxiety and depression should be assessed separately. Additional use of a self-rating instrument for depression and anxiety, such as HADS, is recommended when SF-36 is used for quality of life (QL) assessment.  相似文献   
85.
Dilution of respiratory solutes in exhaled condensates   总被引:9,自引:0,他引:9  
Most exhaled water is produced as gaseous water vapor, which can be collected in cooled condensers. The presence of nonvolatile solutes in these condensates suggests that droplets of respiratory fluid (RF) have also been collected. However, calculation of RF solute concentrations from condensates requires estimation of the dilution of RF droplets by water vapor. We used condensate electrolyte concentrations to calculate the dilution of RF droplets in condensates from 20 normal subjects. The total ionic concentration (conductivity) was 497 plus minus 68 (mean plus minus SEM) muM. Of this, 229 plus minus 43 muM was NH(4)(+), but little NH(4)(+) was collected from subjects with tracheostomies, indicating oral formation. The Na+ concentration in condensate ([Na+](cond)) averaged 242 plus minus 43 muM. Large variations in [Na(+)](cond) correlated well with variations of K+ in condensate ([K+](cond)) and Cl-) in condensate ([Cl-](cond)), and were attributed to differences in respiratory droplet dilution. Dividing condensate values of ([Na+] + [K+] ) by those of plasma indicated that RF represented between 0.01% and 2.00% of condensate volumes. Calculated values for Na+, K+, Cl-, lactate, and protein in RF were [Na+](RF) = 91 +/- 8 mM, [K+](RF) = 60 +/- 11 mM, [Cl-](RF) = 102 +/- 17 mM, [lactate](RF) = 44 +/- 17 mM, and [protein](RF) = 7.63 +/- 1.82 g/dl, respectively.  相似文献   
86.
5-Flourouracil(5-FU) is one of well known anti-cancer drugs, but its toxicity in normal lymphocytes remains a major problem in chemotherapy. The eastern traditional drug, Bupleuri radix(BR), has been used for the treatment of liver diseases and contains series of triterpene saponins.  相似文献   
87.
BACKGROUND: To quantify the long-term risk of second cancers (SCs) up to 30 years after primary treatment for Hodgkin's disease (HD) Material and methods In the period 1968 to 1985, an unselected population of 1024 patients started treatment for HD at the Norwegian Radium Hospital (NRH) and were followed for SC from 1969 through 1998 by The Norwegian Cancer Registry. The median age at diagnosis of HD was 40 years, and the median time at follow-up was 14 years. RESULTS: Of 197 SCs, 14 were acute non-lymphocytic leukemia (ANLL), 31 non-Hodgkin's lymphoma (NHL) and 152 solid cancers. The standardized incidence ratio (SIR) was significantly increased for SCs as a group, and for the subgroups ANLL, NHL, lung cancer, breast cancer, stomach cancer and melanoma. ANLL was related to heavy treatment with chemotherapy (CT) and combined CT and radiotherapy (RT), NHL was not treatment related, and solid tumors were related to radiotherapy only or combined RT and CT. The SIR of ANLL and NHL reached a peak between 5 and 10 years after treatment. Solid and non-solid tumors increased with young age at diagnosis of HD and solid tumors increased with follow-up time up to 28 years CONCLUSION: In a long-term follow-up study of HD patients of all ages, the SIR of solid tumors was high in patients treated at young age and decreased with increasing age. Most solid tumors had started within or at the edge of the irradiated field, and SIR of solid tumors increased even 20-30 years after diagnosis.  相似文献   
88.
Approximately 22 million children are injured in the United States annually. Children are uniquely susceptible to craniofacial trauma because of their greater cranial-mass-to-body ratio. The pediatric population sustains 1% to 14.7% of all facial fractures. The majority of these injuries are encountered by boys (53.7% - 80%) who are involved in motor vehicle accidents (up to 80.2%). The incidence of other systemic injury concomitant to facial trauma is significant (10.4% - 88%). The management of the pediatric patient with maxillofacial injury should take into consideration the differences in anatomy and physiology between children and adults, the presence of concomitant injury, the particular stage in growth and development (anatomic, physiologic, and psychologic), and the specific injuries and anatomic sites that the injuries affect. This comprehensive review, based on the last 25 years of the world's English-speaking surgical literature, presents current thoughts on the anatomic and physiologic differences between adults and children, a synopsis of childhood growth and development, and an overview of state-of-the-art management of the pediatric patient who has sustained maxillofacial injury.  相似文献   
89.
Dehydroepiandrosterone (DHEA) is an intermediate product in the synthesis of male and female sex hormones in the adrenal cortex of man. In livers of rats and mice DHEA increases the levels of cytochrome P450 IVA and peroxisomal beta-oxidation enzymes associated with peroxisome proliferation. Prolonged treatment of rats with DHEA induces liver tumors that are more frequent in females arising mainly in the periportal regions of the liver lobule (Metzger et al., Toxicol. Pathol. 23, 591-605, 1995). Because of paucity of information on hepatic zonation of peroxisomal response to DHEA and controversial reports on gender-specific differences of its effects the present study was undertaken using qualitative immunohistochemical and quantitative immunoelectron microscopical techniques in addition to Western blotting. Rats were treated for 24 weeks with 0.6% DHEA supplied with diet. Immunoblot analysis revealed marked induction of peroxisomal beta- oxidation enzymes, which by quantitative analysis was equally strong in male and female animals, whilst catalase and urate-oxidase were not increased. Cytochrome P450 IVA, in contrast, was induced significantly stronger in male than in female rats. Immunohistochemistry confirmed the induction of cytochrome P450 IVA showing a marked lobular gradient in female animals with strong induction in pericentral and almost no induction in periportal regions of the liver lobule. In male animals cytochrome P450 IVA was expressed more uniformly across the liver lobule. A similar sex specific zone-dependent response was observed for peroxisomes. DHEA induced in females a significant zonal gradient with marked peroxisome proliferation and a strong induction of peroxisomal hydratase/dehydrogenase in pericentral hepatocytes and a much smaller response in periportal regions. Livers of male animals, in contrast, showed a uniform peroxisomal proliferation to DHEA with only slight zonal differences. The striking homologies of the induction patterns of cytochrome P450 IVA and the peroxisome proliferation in both sexes support the notion of a functional relationship. In view of the almost exclusive periportal localization of DHEA-induced tumors in female rats in contrast to the pericentral localization of the peroxisomal proliferation shown by this study, it seems likely that other factors in addition to peroxisome proliferation may contribute to the hepatocarcinogenic effect of DHEA.   相似文献   
90.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号