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   546篇
  免费   56篇
  国内免费   6篇
儿科学   23篇
妇产科学   4篇
基础医学   96篇
口腔科学   10篇
临床医学   55篇
内科学   128篇
皮肤病学   8篇
神经病学   20篇
特种医学   54篇
外科学   99篇
综合类   3篇
预防医学   22篇
眼科学   4篇
药学   36篇
肿瘤学   46篇
  2022年   5篇
  2021年   8篇
  2020年   12篇
  2018年   8篇
  2017年   6篇
  2016年   10篇
  2015年   13篇
  2014年   11篇
  2013年   23篇
  2012年   28篇
  2011年   26篇
  2010年   23篇
  2009年   15篇
  2008年   20篇
  2007年   19篇
  2006年   18篇
  2005年   23篇
  2004年   25篇
  2003年   17篇
  2002年   22篇
  2001年   18篇
  2000年   11篇
  1999年   14篇
  1998年   21篇
  1997年   19篇
  1996年   21篇
  1995年   12篇
  1994年   8篇
  1993年   9篇
  1992年   8篇
  1991年   5篇
  1990年   11篇
  1989年   9篇
  1988年   5篇
  1987年   5篇
  1986年   10篇
  1985年   4篇
  1984年   4篇
  1983年   4篇
  1982年   5篇
  1981年   5篇
  1980年   6篇
  1979年   4篇
  1978年   4篇
  1977年   13篇
  1976年   4篇
  1973年   4篇
  1971年   5篇
  1970年   3篇
  1969年   4篇
排序方式: 共有608条查询结果,搜索用时 15 毫秒
21.
In US men, the incidence of anal cancer, the primary cause of which is human papillomavirus (HPV) infection, has increased almost 3-fold in 3 decades; however, little is known about the epidemiology of anal HPV infection, especially in heterosexual men. In 2 US cities, behavioral data and anal biological specimens were collected from 253 men who acknowledged having engaged in sexual intercourse with a woman during the preceding year. On the basis of DNA analysis, overall prevalence of anal HPV infection was found to be 24.8% in 222 men who acknowledged having had no prior sexual intercourse with men. Of the men with anal HPV infection, 33.3% had an oncogenic HPV type. Risk factors independently associated with anal HPV were lifetime number of female sex partners and frequency of sex with females during the preceding month. These results suggest that anal HPV infection may be common in heterosexual men.  相似文献   
22.
The present study examined whether there were different growth profiles in basic need frustration in elite junior performers over a nine-month period. Subsequently, we examined whether the identified growth profiles differed in their levels of perfectionistic strivings and evaluative concerns measured at baseline and, additionally, whether they were associated with higher or lower levels of anxiety and perceived performance level in the end of the period. A sample of 259 (Mage = 17.31; SDage = 0.97) elite junior performers from sports and performing arts completed an online questionnaire to report their self-ratings of the study variables. The analyses were conducted using growth mixture modeling in Mplus 8.0. Two main contrasting growth profiles were identified in each of the basic need frustration. Perfectionistic strivings were overall higher than evaluative concerns, but did not differ between the growth profiles. Conversely, evaluative concerns differed significantly between the identified growth profiles. Higher levels of evaluative concerns were associated with the most maladaptive growth profiles. Indeed, elite junior performers, who experienced moderate and increasing levels of competence and autonomy frustration, reported higher levels of anxiety and lower levels of perceived performance level than those who reported low and decreasing levels of competence and autonomy frustration. Based on these findings, evaluative concerns and basic need frustration appear to play key roles in the development of maladaptive motivational processes over time.  相似文献   
23.
The lack of efficient tools for identifying immunological correlates of tuberculosis (TB) protection or risk of disease progression impedes the development of improved control strategies. To more clearly understand the host response in TB, we recently established an imaging flow cytometer-based in-vitro assay, which assesses multiple aspects of T cell–monocyte interaction. Here, we extended our previous work and characterized communication between T cells and monocytes using clinical samples from individuals with different TB infection status and healthy controls from a TB endemic setting. To identify T cell–monocyte conjugates, peripheral blood mononuclear cells (PBMC) were stimulated with ds-Red-expressing Mycobacterium bovis bacille Calmette–Guérin or 6-kDa early secreted antigenic target (ESAT 6) peptides for 6 h, and analyzed by imaging flow cytometer (IFC). We then enumerated T cell–monocyte conjugates using polarization of T cell receptor (TCR) and F-actin as markers for synapse formation, and nuclear factor kappa B (NF-κB) nuclear translocation in the T cells. We observed a reduced frequency of T cell–monocyte conjugates in cells from patients with active pulmonary tuberculosis (pTB) compared to latent TB-infected (LTBI) and healthy controls. When we monitored NF-κB nuclear translocation in T cells interacting with monocytes, the proportion of responding cells was significantly higher in active pTB compared with LTBI and controls. Overall, these data underscore the need to consider multiple immunological parameters against TB, where IFC could be a valuable tool.  相似文献   
24.
Incidence of human papillomavirus (HPV) attributable oropharyngeal cancers (OPCs) has been increasing globally, especially among men in high-income countries. There is a lack of studies comparing oral HPV prevalence by age and country among healthy men. The purpose of our study was to assess oral HPV prevalence by country and age. Participants of the HPV Infection in Men Study (HIM), a cohort of 3,098 healthy men from São Paulo, Brazil, Cuernavaca, Mexico and Tampa, USA, were studied. Oral HPV prevalence and type distribution were assessed using the SPF10 PCR-DEIA-LiPA25 system. The prevalence of any HPV in Brazil, Mexico and the US was 8.7% (95% CI: 7.1%, 10.4%), 10.0% (95% CI: 8.3%, 12.1%) and 7.6% (95% CI: 5.9%, 9.5%), respectively, while the prevalence of high-risk HPV was 5.3% (95% CI: 4.1%, 6.7%), 7.3% (95% CI: 5.7%, 9.0%) and 5.4% (95% CI: 4.0%, 7.0%), respectively. No significant differences in prevalence of grouped HPV types were observed by country despite significant differences in sexual behaviors. However, the age-specific prevalence of oral HPV differed by country. Brazilian (6.0% [95% CI: 3.4%, 9.7%]) and Mexican (9.2% [95% CI: 5.6%, 14.0%]) participants had peak high-risk HPV prevalence among men aged 41–50 years whereas the US participants had peak prevalence at ages 31–40 years (11.0% [95% CI: 6.4%, 17.3%]). In conclusion, oral HPV prevalence was low with no difference in overall prevalence observed by country. Factors associated with the differences in oral HPV age-patterning by country and sexual orientation require further study.  相似文献   
25.
AIM:To determine the splanchnic blood flow and oxygen uptake in healthy-subjects and patients and to relate the findings to body-composition.METHODS:The total splanchnic blood flow (SBF) and oxygen uptake (SO2U) were measured in 20 healthy volunteers (10 women) and 29 patients with suspected chronic intestinal ischemia (15 women),age 40-85 years,prior to and after a standard meal.The method is based on the Fick principle using the continuous infusion of an indicator (99mTechnetium-labelled mebrofenin) and catheterization of an artery and the hepatic vein.An angiography of the intestinal arteries was performed during the same investigation.A whole-body dual-energy x-ray absorptiometry scan was performedin healthy volunteers to determine body composition.RESULTS:Angiography revealed no atherosclerotic lesions in the intestinal arteries.The mean baseline SBF was 1087mL/min (731-1390),and this value increased significantly to 1787 mL/min after the meal in healthy volunteers (P<0.001).The baseline SBF in patients was 1080 mL/min,which increased to 1718 mL/min postprandially (P<0.001).The baseline SBF was independent of age,sex,lean body mass and percentage of body fat.The mean meal-induced increase in SBF was equal to 282mL/min + 5.4mL/min × bodyweight,(P=0.025).The SO2U in healthy volunteers and patients was 50.7mL/min and 48.0mL/min,respectively,and these values increased to 77.5 mL/min and 75mL/min postprandially,respectively.Both baseline and postprandial SO2U were directly related to lean body mass.Age and sex exerted no impact on SO2U.CONCLUSION:A direct correlation between body weight and the postprandial increase in SBF was observed.The effect of body weight should be considered in the diagnosis of chronic intestinal ischemia.  相似文献   
26.
27.
Objective Although vitamin D and bone metabolism are closely related, few studies have addressed the effects of vitamin D status on bone in men at time of peak bone mass. The objectives of this study were to evaluate the prevalence of vitamin D inadequacy in a cross‐sectional study in young men and the effects of vitamin D and parathyroid hormone (PTH) on bone mass, bone markers and metabolic function. Design and Participants The study population consisted of 783 men aged 20–29 years. Measurements Bone mineral density (BMD) of the total hip, femoral neck and lumbar spine was measured. dual‐energy X‐ray absorptiometry was used to evaluate total body fat mass (BFAT). Visceral fat mass and abdominal subcutaneous fat mass (ViFM and ScFM) were assessed using magnetic resonance imaging. A radioimmunoassay was used to measure the level of 25‐hydroxy vitamin D (25OHD). Results The prevalence of vitamin deficiency (serum 25OHD < 50 nm ) was 6·3% during summer and 43·6% during winter. Serum 25OHD was associated with BMD at all sites and inversely associated with bone‐specific alkaline phosphatase and directly with carboxyterminal telopeptide of type‐1‐collagen. 25OHD and PTH were inversely associated with BFAT, whereas 25OHD also was inversely associated with body mass index, waist–hip ratio, ViFM and ScFM after adjustment for confounders. The associations were found only to be present in participants with insufficient levels of 25OHD. 25‐Hydroxy vitamin D and PTH were inversely related to insulin resistance in vitamin‐insufficient participants only. No associations between PTH or 25OHD and blood pressure were noted. Conclusion The study showed a high prevalence of 25OHD deficiency in young, northern European men, which was significantly associated with decreased BMD. PTH and 25OHD were found to be inversely related to the markers of insulin resistance.  相似文献   
28.
BACKGROUND: Human papillomavirus (HPV) is sexually transmitted and causes cervical cancer. Although HPV can infect men and women, little is known about infection in men. Specifically, the prevalence of type-specific HPV infection and the distribution of infections by anogenital anatomic site in men are incompletely characterized. METHODS: We tested 463 men ages 18 to 40 years for HPV at the glans/corona, penile shaft, scrotum, urethra, perianal area, anal canal, and in a semen sample. Eligible men acknowledged no history of genital warts and had sexual intercourse with a woman within the past year. HPV testing by PCR and reverse line blot genotyping for 37 types was conducted on each of the specimens from the seven sampling sites. RESULTS: When HPV results from any sampling site were considered, 237 (51.2%) men were positive for at least one oncogenic or nononcogenic HPV type, and another 66 (14.3%) men were positive for an unclassified HPV type. The types with the highest prevalence were HPV-16 (11.4%) and 84 (10.6%). External genital samples (glans/corona, shaft, and scrotum) were more likely than anal samples to contain oncogenic HPV (25.1% versus 5.0%). HPV-positive penile shaft and glans/corona samples were also more likely to be infected with multiple HPV types than other sites. CONCLUSIONS: More complete anogenital sampling and sensitive detection for 37 HPV types resulted in a higher HPV prevalence in primarily asymptomatic men than reported previously. The penile shaft was the site most likely to be HPV positive and harbored the greatest proportion of multiple type and oncogenic infections. These results have implications for research of HPV among men and transmission between partners.  相似文献   
29.
Conventional chemotherapy of acute myelogenous leukemia (AML) results in an overall long-term disease-free survival of less than 50%, but for selected subsets of younger patients the prognosis can be improved by allogeneic stem cell transplantation. The use of autologous stem cell transplantation is now investigated as an alternative to allotransplantation due to its lower risk of serious complications. However, autotransplantation is associated with a relatively high risk of post-transplant AML relapse that can be derived from contaminating leukemia cells in the autograft. Peripheral blood mobilized stem cell (PBSC) grafts usually contain a higher number of platelets. The degree of platelet contamination is determined by the peripheral blood platelet count at the time of harvesting, and the platelets become activated and release soluble mediators during the ex vivo handling of PBSC grafts. Many of these platelet-derived mediators can bind to specific receptors expressed by AML blasts, and the platelet contamination may then alter AML blast survival and thereby influence the risk of post-transplant leukemia relapse. Therefore, we conclude that the platelet contamination of autologous stem cell grafts is possibly of clinical importance, but the effect of this nonstandardized parameter is difficult to predict in individual patients because the number of graft-contaminating platelets, the degree of platelet activation, and the effects of platelet-derived mediators on AML blasts differ between patients.  相似文献   
30.
Background: We concluded a program in which we administeredradiotherapy only to clinical stages I and II Hodgkin's diseasepatients at standard risk, with the addition of 4 cycles ofcombination chemotherapy before radiotherapy for high-risk patients. Patients and methods: From 1980 to 1991, 313 patients with clinicalstages I or II Hodgkin's disease underwent treatment in ourhospital. Fifty percent of the patients in groups previouslyidentified as being at high risk for relapse received 4 cyclesof combination chemotherapy before radiotherapy. The remaininghalf of the patients received radiotherapy only. Results: Low- and high-risk patients aged 15–59 yearshad, respectively, complete remission (CR) rates of 97% and94%, 5-year survivals of 95% and 91%, and 5-year freedom fromrelapse (FFR) rates of 78% and 89%. Older low- and high-riskgroups had CR rates of 97% and 93%, 5-year survivals of 60%and 56% and 5-year FFR of 77% and 93%, respectively. Conclusion: Here we present our favorable results after treatingstandard-risk patients with clinical stages I and II Hodgkin'sdisease with radiotherapy only. With the addition of chemotherapy,the rate of relapse in the high-risk patients was reduced belowthat of the standard-risk patients. Overall survival was thesame for the high- and standard-risk patients. adjuvant chemotherapy, Hodgkin's disease, radiotherapy, stages I and II  相似文献   
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