首页 | 官方网站   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   3348篇
  免费   191篇
  国内免费   19篇
医药卫生   3558篇
  2023年   21篇
  2022年   20篇
  2021年   87篇
  2020年   58篇
  2019年   91篇
  2018年   122篇
  2017年   77篇
  2016年   87篇
  2015年   102篇
  2014年   124篇
  2013年   183篇
  2012年   209篇
  2011年   197篇
  2010年   118篇
  2009年   100篇
  2008年   171篇
  2007年   164篇
  2006年   164篇
  2005年   153篇
  2004年   146篇
  2003年   148篇
  2002年   129篇
  2001年   73篇
  2000年   87篇
  1999年   77篇
  1998年   31篇
  1997年   25篇
  1996年   24篇
  1995年   28篇
  1994年   30篇
  1993年   19篇
  1992年   48篇
  1991年   31篇
  1990年   39篇
  1989年   33篇
  1988年   34篇
  1987年   33篇
  1986年   20篇
  1985年   35篇
  1984年   25篇
  1983年   22篇
  1982年   18篇
  1980年   14篇
  1979年   17篇
  1977年   9篇
  1975年   11篇
  1973年   8篇
  1971年   15篇
  1970年   9篇
  1967年   11篇
排序方式: 共有3558条查询结果,搜索用时 15 毫秒
1.
Previous studies on the immunogenicity of SARS-CoV-2 mRNA vaccines showed a reduced seroconversion in cancer patients. The aim of our study is to evaluate the immunogenicity of two doses of mRNA vaccines in solid cancer patients with or without a previous exposure to the virus. This is a single-institution, prospective, nonrandomized study. Patients in active treatment and a control cohort of healthy people received two doses of BNT162b2 (Comirnaty, BioNTech/Pfizer, The United States) or mRNA-1273 (Spikevax, Moderna). Vaccine was administered before starting anticancer therapy or on the first day of the treatment cycle. SARS-CoV-2 antibody levels against S1, RBD (to evaluate vaccine response) and N proteins (to evaluate previous infection) were measured in plasma before the first dose and 30 days after the second one. From January to June 2021, 195 consecutive cancer patients and 20 healthy controls were enrolled. Thirty-one cancer patients had a previous exposure to SARS-CoV-2. Cancer patients previously exposed to the virus had significantly higher median levels of anti-S1 and anti-RBD IgG, compared to healthy controls (P = .0349) and to cancer patients without a previous infection (P < .001). Vaccine type (anti-S1: P < .0001; anti-RBD: P = .0045), comorbidities (anti-S1: P = .0274; anti-RBD: P = .0048) and the use of G-CSF (anti-S1: P = .0151) negatively affected the antibody response. Conversely, previous exposure to SARS-CoV-2 significantly enhanced the response to vaccination (anti-S1: P < .0001; anti-RBD: P = .0026). Vaccine immunogenicity in cancer patients with a previous exposure to SARS-CoV-2 seems comparable to that of healthy subjects. On the other hand, clinical variables of immune frailty negatively affect humoral immune response to vaccination.  相似文献   
2.
Background:Risk behaviors are frequent among young adults and they are particularly relevant when considering healthcare students.Objectives:The study is aimed to examine the prevalence of smoking, binge drinking, physical inactivity, and excessive bodyweight in a population of healthcare students attending an Italian university.Methods:Healthcare students filled an anonymous multiple-choice questionnaire on the occasion of the occupational health visit that preceded their hospital internship. The questionnaire covered socio-demographic characteristics (including student’s working status and cohabitation) and risk behaviors. We evaluated the prevalence of risk behaviors and their association with socio-demographic characteristics.Results:The sample consisted of 494 students (65% women): 23.2% were smokers, 7.9% had excessive bodyweight, 35% did not practice any physical activity and 50% reported binge drinking at least once in the last 12 months. We found associations of male sex (30.5%) and being nursing students (29.9%) with smoking habit. The frequency of binge drinking was higher in men (38.4%), working students (53.9%), and among those who lived without family (50%). Physical inactivity was associated with female sex (44.2%) and living without family (57.1%). Finally, the co-presence of 2 risk behaviors or more was higher in men (36.8%), in nursing students (39.6%) and in working students (44.7%).Conclusions:Our findings regarding the prevalence of risk behaviors and their potential association with socio-demographic factors may be a clue to the definition of targeted strategies aimed at reducing of risk behaviors among healthcare students.Key words: risk behaviors, healthcare students, smoking, binge drinking, physical inactivity  相似文献   
3.
Purpose: To measure the choroidal thickness among subjects with human immunodeficiency virus (HIV) infection from two diverse ethnic populations and to compare it with healthy controls.

Methods: Subjects with HIV infection and healthy controls were enrolled in two referring centers in Italy and India. Clinical data were collected. All subjects underwent enhanced-depth imaging optical coherence tomography and measurement of choroidal thickness.

Results: A total of 68 eyes from 68 patients with HIV (44 Caucasian, 24 Indians) and 60 eyes from 60 healthy volunteers (36 Caucasian, 24 Indians) were included. Mean choroidal thickness was significantly higher in HIV patients compared to controls (312.91 ± 65 µm vs. 266.57 ± 47 µm; p < 0.001). Choroidal thickness was higher among subjects with HIV-related retinopathy compared to HIV without retinopathy (285 ± 30 µm vs. 352 ± 17 µm; p < 0.01).

Conclusions: Patients with HIV infection, especially with HIV microangiopathy, have thicker choroid compared to age- and gender-matched healthy control subjects. These changes may be related to HIV-associated choroidal vascular dysfunction.  相似文献   

4.

Background

Available models for predicting lymph node invasion (LNI) in prostate cancer (PCa) patients undergoing radical prostatectomy (RP) might not be applicable to men diagnosed via magnetic resonance imaging (MRI)-targeted biopsies.

Objective

To assess the accuracy of available tools to predict LNI and to develop a novel model for men diagnosed via MRI-targeted biopsies.

Design, setting, and participants

A total of 497 patients diagnosed via MRI-targeted biopsies and treated with RP and extended pelvic lymph node dissection (ePLND) at five institutions were retrospectively identified.

Outcome measurements and statistical analyses

Three available models predicting LNI were evaluated using the area under the receiver operating characteristic curve (AUC), calibration plots, and decision curve analyses. A nomogram predicting LNI was developed and internally validated.

Results and limitations

Overall, 62 patients (12.5%) had LNI. The median number of nodes removed was 15. The AUC for the Briganti 2012, Briganti 2017, and MSKCC nomograms was 82%, 82%, and 81%, respectively, and their calibration characteristics were suboptimal. A model including PSA, clinical stage and maximum diameter of the index lesion on multiparametric MRI (mpMRI), grade group on targeted biopsy, and the presence of clinically significant PCa on concomitant systematic biopsy had an AUC of 86% and represented the basis for a coefficient-based nomogram. This tool exhibited a higher AUC and higher net benefit compared to available models developed using standard biopsies. Using a cutoff of 7%, 244 ePLNDs (57%) would be spared and a lower number of LNIs would be missed compared to available nomograms (1.6% vs 4.6% vs 4.5% vs 4.2% for the new nomogram vs Briganti 2012 vs Briganti 2017 vs MSKCC).

Conclusions

Available models predicting LNI are characterized by suboptimal accuracy and clinical net benefit for patients diagnosed via MRI-targeted biopsies. A novel nomogram including mpMRI and MRI-targeted biopsy data should be used to identify candidates for ePLND in this setting.

Patient summary

We developed the first nomogram to predict lymph node invasion (LNI) in prostate cancer patients diagnosed via magnetic resonance imaging-targeted biopsy undergoing radical prostatectomy. Adoption of this model to identify candidates for extended pelvic lymph node dissection could avoid up to 60% of these procedures at the cost of missing only 1.6% patients with LNI.  相似文献   
5.
6.
Pediatric Surgery International - Human breast milk (HBM), which contains an abundant supply of exosomes, is known to prevent necrotizing enterocolitis (NEC). Preterm infants are commonly given...  相似文献   
7.
8.
The aim of our study was to investigate the impact of the epsilon phenotype in brain glucose consumption in a population with Alzheimer’s disease. Statistical Parametric Mapping (SPM8) was used to investigate differences in brain glucose consumption (as detectable by means of 18F FDG-PET/CT) in the population examined. A total of 129 patients (72 females and 57 males) with a diagnosis of probable AD according to the NINCDS-ADRDA criteria underwent the PET/CT examination. The mean (SD) age of the patients was 70 (± 7) years; the mean Mini-Mental State Examination was 19(± 5.6). 59 expressed epsilon 4 phenotype (E4) and 70 expressed the epsilon 3 phenotype (E3). Cerebral spinal fluid amyloid, tau, and t-tau have been measured resulting equal to 367.4 (± 149.1), 584.7 (± 312.1), and 79.2(± 45.9) pg/ml, respectively. Patients with confirmed amyloid and Tau changes were classified as AD. Patients with amyloid changes but negative Tau, considered as high risk of AD, were classified as IAD. Age, sex, MMSE, scholarship, and CSF parameters were used as a covariate in the SPM analyses. We did not find significant differences in age, gender, and MMSE and CSF parameters among groups. In the analysis of the AD group as compared to AD-E3, AD-E4 subjects show a significant reduction of brain glucose consumption in inferior frontal gyrus bilaterally (BA 45, BA 47). In the analysis of the IAD group as compared to IAD-E3, IAD-E4 subjects show a significant reduction of brain glucose consumption in right in medial, middle, and superior frontal gyrus (BA10, BA11), and in left medial and middle frontal gyrus (BA10, BA11). The differences between IAD-E3 and AD-E3 and between IAD-E4 and AD-E4 (and vice versa analysis) resulted not significant. APO-e4 is related to a major involvement of the frontal cortex confirming its role of risk factor in AD, while APO-3 seems not related to a specific pattern, supporting the hypothesis of neutral/protective role in AD.  相似文献   
9.
Journal of Neurology - To investigate the prognostic role and the major determinants of serum phosphorylated neurofilament heavy -chain (pNfH) concentration across a large cohort of motor neuron...  相似文献   
10.
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-23

京公网安备 11010802026262号