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   8418篇
  免费   632篇
  国内免费   22篇
耳鼻咽喉   78篇
儿科学   223篇
妇产科学   284篇
基础医学   1305篇
口腔科学   85篇
临床医学   665篇
内科学   1608篇
皮肤病学   381篇
神经病学   836篇
特种医学   294篇
外科学   1078篇
综合类   58篇
一般理论   1篇
预防医学   839篇
眼科学   90篇
药学   663篇
中国医学   28篇
肿瘤学   556篇
  2023年   68篇
  2022年   74篇
  2021年   131篇
  2020年   114篇
  2019年   161篇
  2018年   171篇
  2017年   149篇
  2016年   164篇
  2015年   161篇
  2014年   196篇
  2013年   355篇
  2012年   435篇
  2011年   392篇
  2010年   252篇
  2009年   247篇
  2008年   375篇
  2007年   338篇
  2006年   385篇
  2005年   341篇
  2004年   350篇
  2003年   301篇
  2002年   269篇
  2001年   250篇
  2000年   264篇
  1999年   236篇
  1998年   118篇
  1997年   79篇
  1996年   88篇
  1995年   94篇
  1994年   87篇
  1993年   71篇
  1992年   163篇
  1991年   165篇
  1990年   165篇
  1989年   177篇
  1988年   168篇
  1987年   151篇
  1986年   125篇
  1985年   128篇
  1984年   114篇
  1983年   83篇
  1982年   67篇
  1981年   51篇
  1979年   83篇
  1978年   55篇
  1977年   66篇
  1976年   53篇
  1975年   50篇
  1974年   56篇
  1973年   52篇
排序方式: 共有9072条查询结果,搜索用时 31 毫秒
51.
52.
OBJECTIVE: Testing association of the Asn363Ser variant of the glucocorticoid gene with measures of obesity and weight gain. SUBJECTS: 741 obese subjects (BMI > or = 31 kg/m(2) at selection) and 854 random control subjects from the same population, examined at draft board examination and after on average 27.4+/- y. A lean control group (n=351) was further selected as the fraction from the cohort group having a BMI below 25.0 kg/m(2) at the latest examination. METHODS: Using PCR-RFLP subjects were genotyped for the Asn363Ser variant and grouped according to genotype. RESULTS: The prevalence of the Ser363 allele was 4.7% (95% Cl: 3.3-6.2%) among the obese, 4.1% (2.7-5.5%) among the random cohort subjects and 4.3% (2.1-6.5%) among lean control subjects, respectively, showing no significant differences between the groups (P > 0.1). Furthermore, no differences in BMI, waist-hip ratio or weight gain were seen within any of the groups when defined according to the glucocorticoid receptor genotype. CONCLUSION: In the examined population this marker is not a relevant predictor of obesity.  相似文献   
53.
54.
It has been proposed that the structural and numerical chromosome abnormalities recorded in breast cancer could be the result of telomere dysfunction and that telomerase is activated de novo to provide a survival mechanism curtailing further chromosomal aberrations. However, recent in vivo and in vitro data show that the ectopic expression of telomerase promotes tumorigenesis via a telomere length-independent mechanism. In this study, the relation between telomerase expression and the extent of chromosomal aberrations was investigated in 62 primary breast carcinomas. Telomerase activity was measured using a polymerase chain reaction-based telomeric repeat amplification protocol assay and 92% of the tumors were found to express telomerase with a relative activity ranging from 0 to 3839.6. Genetic alterations were determined by G-banding and comparative genomic hybridization analysis and 97% of the tumors exhibited chromosomal aberrations ranging from 0 to 44 (average: 10.98). In the overall series, the relationship between telomerase activity levels and genetic changes could be best described by a quadratic model, whereas in tumors with below-average genetic alteration numbers, a significant positive association was recorded between the two variables (coefficient=0.374, P=.017). The relationship between telomerase activity levels and the extent of genetic alteration may reflect the complex effect of telomerase activation upon tumor progression in breast carcinomas.  相似文献   
55.
The prognostic significance of eosinophilia after myeloablative allogeneic stem cell transplantation (ASCT) remains to be established. Patients, whom developed chronic graft-versus-host disease (cGVHD) after ASCT, were included (n = 142). Eosinophil count was analyzed at cGVHD onset. We observed no significant association between EO and the grade of cGVHD, thrombocytopenia, nor extensive skin involvement. Importantly, we observed no significant association between cGVHD with concomitant eosinophilia and long-term clinical outcomes, and subgroup analyses revealed a considerable confounding effect of ongoing steroid treatment. In conclusion, we advocate that prognostic conclusions regarding cGVHD with concomitant eosinophilia after ASCT should be interpreted with caution.  相似文献   
56.
Objective To assess the relation between work-related stressors and breast cancer incidence and prognostic characteristics (estrogen receptor status, grade, lymph node status, size, stage) at the time of diagnosis. Methods The 18,932 women included in the Danish Nurse Cohort reported work-related stressors in 1993 and again in 1999 and were followed until the end of 2003 in national registries. Prognostic characteristics were obtained from a clinical database and fewer than 0.1% were lost to follow up. Results During follow-up, 455 women were diagnosed with breast cancer. Neither women with high work pressure (HR = 1.17; 95% CI: 0.79, 1.73) nor women with self-reported low influence on work organization (0.98; 0.69, 1.39) or long working hours (0.93; 0.54, 1.58) were at higher risk of breast cancer than women with no such stressors. Women with high work tempo had a slightly higher risk of breast cancer (1.25; 1.02, 1.54) than women with a suitable work tempo, but there was no dose-response effect. There were no clear differences in the prognostic characteristics of breast tumors diagnosed in women with and without work-related stressors. Conclusions Work-related stressors do not affect breast cancer risk or the prognostic characteristics of incident breast cancers at the time of diagnosis. These results may be a comfort to working women and can hopefully prevent self-blaming among women who develop breast cancer.  相似文献   
57.
58.
Neck injury sustained during exposure to high-G forces in the F16B   总被引:3,自引:0,他引:3  
Neck pain is a frequent complaint among aviators flying high performance fighter (HPF) aircraft. However, very few--if any--cases of subjective symptoms have been confirmed by objective methods and reported in the literature. The present paper relates an incident of documented injury of the cervical spine which occurred during an abrupt and violent maneouver in the F16B. The rear seat occupant, a flight surgeon, who had just handed over controls to the instructor flying from the front seat, was caught unaware. He suffered a ligament injury C5-6 and a sliding of the C6 relative to the C5. It is concluded: 1) The accelerative forces in HPF aircraft can cause serious injury to the cervical spine and its supporting structures in the neck. 2) Aircrew not engaged in the flying task may be at risk if left ignorant of pilots' intentions. 3) Lightweight helmets reduce the medical hazards imposed upon aviators in the high-G environment. 4) Specific exercises aimed at strengthening the neck muscles are encouraged.  相似文献   
59.
60.
OBJECTIVES: This study estimated the proportion of HIV-infected adults who have been assaulted by a partner or someone important to them since their HIV diagnosis and the extent to which they reported HIV-seropositive status as a cause of the violence. METHODS: Study participants were from a nationally representative probability sample of 2864 HIV-infected adults who were receiving medical care and were enrolled in the HIV Costs and Service Utilization Study. All interviews (91% in person, 9% by telephone) were conducted with computer-assisted personal interviewing instruments. Interviews began in January 1996 and ended 15 months later. RESULTS: Overall, 20.5% of the women, 11.5% of the men who reported having sex with men, and 7.5% of the heterosexual men reported physical harm since diagnosis, of whom nearly half reported HIV-seropositive status as a cause of violent episodes. CONCLUSIONS: HIV-related care is an appropriate setting for routine assessment of violence. Programs to cross-train staff in antiviolence agencies and HIV care facilities need to be developed for men and women with HIV infection.  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