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   5409篇
  免费   356篇
  国内免费   16篇
耳鼻咽喉   48篇
儿科学   169篇
妇产科学   153篇
基础医学   611篇
口腔科学   129篇
临床医学   660篇
内科学   949篇
皮肤病学   65篇
神经病学   410篇
特种医学   151篇
外科学   679篇
综合类   42篇
一般理论   5篇
预防医学   615篇
眼科学   78篇
药学   355篇
中国医学   7篇
肿瘤学   655篇
  2023年   27篇
  2022年   37篇
  2021年   110篇
  2020年   93篇
  2019年   112篇
  2018年   138篇
  2017年   115篇
  2016年   110篇
  2015年   140篇
  2014年   194篇
  2013年   290篇
  2012年   344篇
  2011年   382篇
  2010年   242篇
  2009年   192篇
  2008年   360篇
  2007年   351篇
  2006年   351篇
  2005年   311篇
  2004年   304篇
  2003年   280篇
  2002年   254篇
  2001年   90篇
  2000年   60篇
  1999年   77篇
  1998年   68篇
  1997年   64篇
  1996年   50篇
  1995年   51篇
  1994年   45篇
  1993年   43篇
  1992年   48篇
  1991年   60篇
  1990年   48篇
  1989年   24篇
  1988年   28篇
  1987年   37篇
  1986年   25篇
  1985年   23篇
  1984年   30篇
  1983年   19篇
  1982年   24篇
  1981年   16篇
  1980年   22篇
  1979年   9篇
  1978年   12篇
  1977年   9篇
  1975年   8篇
  1974年   8篇
  1967年   8篇
排序方式: 共有5781条查询结果,搜索用时 31 毫秒
91.
92.
Aims To discover whether the number of fatal alcohol peaks during festivities characterized by unrestrained drinking and relates to sales of alcoholic beverages. Design Time‐series and cross‐sectional. Data Fatal alcohol poisonings and retail alcohol sales in Finland in 1983–99. Findings Fatal alcohol poisonings were found to peak during weekends and in the May Day, Midsummer Day and Christmas celebrations. Regression analysis of quarterly series lead to a model showing that 1% increase in the sales of spirits increases the number of fatal alcohol poisonings by 0.4%. Conclusions At the population level, increases in the sales of spirits and periods of hard drinking seem to increase deaths from alcohol poisoning. The findings could be of use in efforts to decrease hard drinking.  相似文献   
93.
94.
Objectives: Mechanical neck pain (MNP) is common in the athletic population. While symptoms may present at the cervical spine for patients complaining of MNP, thoracic spinal alignment or dysfunction may influence cervical positioning and overall cervical function. Clinicians often employ cervical high-velocity low-amplitude (HVLA) thrust manipulations to treat MNP, albeit with a small level of inherent risk. Mulligan Concept positional sustained natural apophyseal glides (SNAGs) directed at the cervicothoracic region are emerging to treat patients with cervical pain and dysfunction, as evidence supporting an interdependent relationship between the thoracic and cervical spine grows. The purpose of this a priori study was to evaluate outcome measures of patients classified with MNP treated with the Mulligan Concept Positional SNAGs. Methods: Ten consecutive young-adult patients, ages ranging from 15 to 18 years (mean = 16.5 ± 1.78), classified with MNP were treated utilizing Mulligan Concept Positional SNAGs. The Numeric Rating Scale (NRS), Patient-Specific Functional Scale (PSFS), Neck Disability Index (NDI), Disablement in the Physically Active (DPAS), and Fear-Avoidance Based Questionnaire-Physical Activity (FABQPA) were collected for inclusion criteria and to identify patient-reported pain and dysfunction. Results: Patients reported decreases in pain on the NRS [5.4 to .16, p = .001], increases in function on the PSFS [5.2 to 10, p = .001], and increases in cervical range of motion (CROM) [ext p = .003, flex p = .009, left rot p = .001, right rot p = .002] immediately post-treatment and between treatments. Discussion: Positional SNAGs directed at the cervicothoracic region may address a variety of patient reported symptoms for MNP, and the number of treatment sessions needed for symptom resolution may be closer to a single session rather than multiple treatments. Level of Evidence: 4.  相似文献   
95.

Purpose

This study aims to develop a constrained local arterial input function (cL-AIF) to improve quantitative analysis of dynamic contrast-enhanced (DCE)-magnetic resonance imaging (MRI) data by accounting for the contrast-agent bolus amplitude error in the voxel-specific AIF.

Procedures

Bayesian probability theory-based parameter estimation and model selection were used to compare tracer kinetic modeling employing either the measured remote-AIF (R-AIF, i.e., the traditional approach) or an inferred cL-AIF against both in silico DCE-MRI data and clinical, cervical cancer DCE-MRI data.

Results

When the data model included the cL-AIF, tracer kinetic parameters were correctly estimated from in silico data under contrast-to-noise conditions typical of clinical DCE-MRI experiments. Considering the clinical cervical cancer data, Bayesian model selection was performed for all tumor voxels of the 16 patients (35,602 voxels in total). Among those voxels, a tracer kinetic model that employed the voxel-specific cL-AIF was preferred (i.e., had a higher posterior probability) in 80 % of the voxels compared to the direct use of a single R-AIF. Maps of spatial variation in voxel-specific AIF bolus amplitude and arrival time for heterogeneous tissues, such as cervical cancer, are accessible with the cL-AIF approach.

Conclusions

The cL-AIF method, which estimates unique local-AIF amplitude and arrival time for each voxel within the tissue of interest, provides better modeling of DCE-MRI data than the use of a single, measured R-AIF. The Bayesian-based data analysis described herein affords estimates of uncertainties for each model parameter, via posterior probability density functions, and voxel-wise comparison across methods/models, via model selection in data modeling.
  相似文献   
96.
97.

Background

Toxicological research suggests that coarse particles (PM10–2.5) are inflammatory, but responses are complex and may be best summarized by multiple inflammatory markers. Few human studies have investigated associations with PM10–2.5 and, of those, none have explored long-term exposures. Here we examine long-term associations with inflammation and coagulation in the Multi-Ethnic Study of Atherosclerosis.

Methods

Participants included 3,295 adults (45–84 years of age) from three metropolitan areas. Site-specific spatial models were used to estimate 5-year concentrations of PM10–2.5 mass and copper, zinc, phosphorus, silicon, and endotoxin found in PM10–2.5. Outcomes included interleukin-6, C-reactive protein, fibrinogen, total homocysteine, D-dimer, factor VIII, plasmin–antiplasmin complex, and inflammation and coagulation scores. We used multivariable regression with multiply imputed data to estimate associations while controlling for potential confounders, including co-pollutants such as fine particulate matter.

Results

Some limited evidence was found of relationships between inflammation and coagulation and PM10–2.5. Endotoxin was the PM10–2.5 component most strongly associated with inflammation, with an interquartile range (IQR) increase (0.08 EU/m3) associated with 0.15 (95% CI: 0.01, 0.28; p = 0.03) and 0.08 (95% CI: –0.07, 0.23; p = 0.28) higher inflammation scores before and after control for city, respectively. Copper was the component with the strongest association with coagulation, with a 4-ng/m3 increase associated with 0.19 (95% CI: 0.08, 0.30; p = 0.0008) and 0.12 (95% CI: –0.05, 0.30; p = 0.16) unit higher coagulation scores before and after city adjustment, respectively.

Conclusions

Our cross-sectional analysis provided some evidence that long-term PM10–2.5 exposure was associated with inflammation and coagulation, but associations were modest and depended on particle composition.

Citation

Adar SD, D’Souza J, Mendelsohn-Victor K, Jacobs DR Jr, Cushman M, Sheppard L, Thorne PS, Burke GL, Daviglus ML, Szpiro AA, Diez Roux AV, Kaufman JD, Larson TV. 2015. Markers of inflammation and coagulation after long-term exposure to coarse particulate matter: a cross-sectional analysis from the Multi-Ethnic Study of Atherosclerosis. Environ Health Perspect 123:541–548; http://dx.doi.org/10.1289/ehp.1308069  相似文献   
98.

Background

The quality of shared decision making for children with serious illness may depend on whether parents and physicians share similar perceptions of problems and hopes for the child.

Objective

(i) Describe the problems and hopes reported by mothers, fathers and physicians of children receiving palliative care; (ii) examine the observed concordance between participants; (iii) examine parental perceived agreement; and (iv) examine whether parents who identified specific problems also specified corresponding hopes, or whether the problems were left ‘hopeless’.

Method

Seventy‐one parents and 43 physicians were asked to report problems and hopes and perceived agreement for 50 children receiving palliative care. Problems and hopes were classified into eight domains. Observed concordance was calculated between parents and between each parent and the physicians.

Results

The most common problem domains were physical body (88%), quality of life (74%) and medical knowledge (48%). The most common hope domains were quality of life (88%), suffering (76%) and physical body (39%). Overall parental dyads demonstrated a high percentage of concordance (82%) regarding reported problem domains and a lower percentage of concordance on hopes (65%). Concordance between parents and physicians regarding specific children was lower on problem (65–66%) and hope domains (59–63%). Respondents who identified problems regarding a child's quality of life or suffering were likely to also report corresponding hopes in these domains (93 and 82%, respectively).

Conclusion

Asking parents and physicians to talk about problems and hopes may provide a straightforward means to improve the quality of shared decision making for critically ill children.  相似文献   
99.
100.
OBJECTIVE: To analyze the association of Wegener's granulomatosis (WG) with 2 single nucleotide polymorphisms (SNP), a +49 A/G polymorphism in coding sequence (CDS) 1 and a C/T base exchange in the promoter region at position -318. METHODS: Restriction enzyme digestion of PCR amplified genomic DNA was used to analyze the CTLA-4 SNP in 32 patients with WG and 100-122 ethnically matched healthy controls. RESULTS: Patients were more often heterozygous for C/T in the promoter region (31% of the patients vs 14% of controls; p < 0.05). Homozygosity for C was less frequent in patients (69% of patients vs 86% of controls; p < 0.05). There was no association with the A/G SNP in CDS 1. There was a linkage disequilibrium between allele A of CDS 1 and the shortest allele, 86 bp, in the (AT)n of the 3' untranslated region in controls but not in patients. CONCLUSION: The CTLA-4 SNP in the promoter region at position -318 is associated with WG. The loss of linkage disequilibrium between allele A of CDS 1 and the short 86 bp in the (AT)n in patients indicates that the promoter SNP and the (AT)n polymorphism are independent genetic risk factors.  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