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   191511篇
  免费   1750篇
  国内免费   158篇
耳鼻咽喉   1242篇
儿科学   6960篇
妇产科学   3527篇
基础医学   18431篇
口腔科学   1930篇
临床医学   13666篇
内科学   35583篇
皮肤病学   903篇
神经病学   17923篇
特种医学   9519篇
外科学   31064篇
综合类   2355篇
一般理论   1篇
预防医学   18632篇
眼科学   2945篇
药学   10276篇
中国医学   654篇
肿瘤学   17808篇
  2023年   119篇
  2022年   253篇
  2021年   499篇
  2020年   272篇
  2019年   393篇
  2018年   22303篇
  2017年   17640篇
  2016年   19810篇
  2015年   1336篇
  2014年   1462篇
  2013年   1596篇
  2012年   8138篇
  2011年   22146篇
  2010年   19497篇
  2009年   12195篇
  2008年   20638篇
  2007年   22829篇
  2006年   1689篇
  2005年   3291篇
  2004年   4380篇
  2003年   5201篇
  2002年   3274篇
  2001年   354篇
  2000年   477篇
  1999年   269篇
  1998年   376篇
  1997年   337篇
  1996年   248篇
  1995年   204篇
  1994年   202篇
  1993年   163篇
  1992年   128篇
  1991年   149篇
  1990年   184篇
  1989年   123篇
  1988年   91篇
  1987年   70篇
  1986年   60篇
  1985年   65篇
  1984年   61篇
  1983年   56篇
  1982年   65篇
  1981年   43篇
  1980年   75篇
  1979年   27篇
  1974年   34篇
  1938年   61篇
  1934年   31篇
  1932年   57篇
  1930年   51篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Nondisclosure of maternal HIV status to young children can negatively impact child functioning; however, many mothers do not disclose due to lack of self-efficacy for the disclosure process. This study examines demographic variations in disclosure self-efficacy, regardless of intention to disclose, and assesses the relationship between self-efficacy and child adjustment via the parent–child relationship among a sample of HIV+ mothers and their healthy children (N = 181 pairs). Mothers completed demographic and self-efficacy measures; children completed measures assessing the parent–child relationship and child adjustment (i.e., worry, self-concept, depression). Across demographics, few mothers reported confidence in disclosure. Results from covariance structural modeling showed mothers endorsing higher self-efficacy had children who reported better relationship quality, and, in turn, reported fewer adjustment difficulties; higher levels of disclosure self-efficacy also directly predicted fewer adjustment problems. Findings offer support for interventions aimed at providing mothers with skills to enhance confidence for disclosing their HIV status.  相似文献   
992.

Background

Symptoms account for more than 400 million clinic visits annually in the USA. The SPADE symptoms (sleep, pain, anxiety, depression, and low energy/fatigue) are particularly prevalent and undertreated.

Objective

To assess the effectiveness of providing PROMIS (Patient-Reported Outcome Measure Information System) symptom scores to clinicians on symptom outcomes.

Design

Randomized clinical trial conducted from March 2015 through May 2016 in general internal medicine and family practice clinics in an academic healthcare system.

Participants

Primary care patients who screened positive for at least one SPADE symptom.

Interventions

After completing the PROMIS symptom measures electronically immediately prior to their visit, the 300 study participants were randomized to a feedback group in which their clinician received a visual display of symptom scores or a control group in which scores were not provided to clinicians.

Main Measures

The primary outcome was the 3-month change in composite SPADE score. Secondary outcomes were individual symptom scores, symptom documentation in the clinic note, symptom-specific clinician actions, and patient satisfaction.

Key Results

Most patients (84%) had multiple clinically significant (T-score?≥?55) SPADE symptoms. Both groups demonstrated moderate symptom improvement with a non-significant trend favoring the feedback compared to control group (between-group difference in composite T-score improvement, 1.1; P?=?0.17). Symptoms present at baseline resolved at 3-month follow-up only one third of the time, and patients frequently still desired treatment. Except for pain, clinically significant symptoms were documented less than half the time. Neither symptom documentation, symptom-specific clinician actions, nor patient satisfaction differed between treatment arms. Predictors of greater symptom improvement included female sex, black race, fewer medical conditions, and receiving care in a family medicine clinic.

Conclusions

Simple feedback of symptom scores to primary care clinicians in the absence of additional systems support or incentives is not superior to usual care in improving symptom outcomes.

Trial Registration

clinicaltrials.gov identifier: NCT02383862.
  相似文献   
993.

Purpose of review

Describe and evaluate the integration of 3D printing-related innovations into current cardiovascular treatment paradigms and examine the state of regulatory and reimbursement hurdles ahead.

Recent findings

Mounting years of clinical experience have established the utility of printed models of patient anatomy in numerous treatment and teaching scenarios, most notably as pre- and intra-procedural planning tools guiding decision-making for congenital heart disease and catheter-based interventions. In part due to a continued lack of reimbursement and under-defined (and slow to evolve) regulatory status, these use cases remain largely investigational even as they grow increasingly routine. Patients, physicians, and/or imaging centers therefore remain burdened by the associated cost to create such models, and the perceptual and decision-making enhancements, while demonstrable and significant, still may not clearly or independently justify a potentially high cost.Simulation and implantable device applications may represent a deeper well of unrealized value in cardiovascular intervention; however, further development of these applications relies on—and is throttled by—progress in material science and tissue-engineering research. The relevance of simulation applications in recent years is also now in competition with digital analogs including augmented and virtual reality. Innovative incorporation of alternative manufacturing processes such as porous scaffold infusion, injection molding, and vascular mesh forming can provide immediate access to more realistic tissue-mimicking materials and custom implantable devices, while comparable and directly printable materials continue to be developed. Tissue-engineering applications remain years if not decades away from a more substantive role in translatable clinical research. Regulatory challenges associated with in-house manufacture of implantable investigational devices are complex and subject to change, and the success of some in navigating these hurdles in non-cardiovascular applications is instructive and encouraging.

Summary

Complex geometries characterizing cardiovascular anatomy are an ideal use case for translating the perceptual advantages of printed models of patient anatomy into better decision-making, especially so in the setting of congenital or post-surgical anatomy. Procedural planning applications take further advantage of the demonstrably robust dimensional reproduction of patient anatomy, with notably rapid integration into surgical and catheter-based intervention workflows. Despite a continued lack of codification in the healthcare system, 2018 could be a milestone year for 3D printing services, pending a successful application for a CPT Category III designation.
  相似文献   
994.

Purpose of review

This article reviews current treatment options and strategies and provides an update on the status of drug development programs of new therapeutic agents for inflammatory bowel diseases (IBD).

Recent findings

In the past two decades, tumor necrosis factor antagonist therapy has given clinicians better treatment options. However, not all patients respond to induction therapy with these agents, and of those initially responding, up to 40% ultimately lose response due to suboptimal drug exposure (e.g., caused by immunogenicity), side effects, or other poorly characterized mechanisms. Recently, additional therapies, such as vedolizumab, an integrin blocker that prevents T cell trafficking to the gut, and ustekinumab, an antibody blocking the common p40 subunit of interleukin (IL)-12 and 23, were introduced to the market. In addition, other agents including novel anti-trafficking therapies (e.g., anti-β7 and sphingosine-1-phosphate receptor modulators), antibodies against p19 (unique to IL-23), and small molecules including Janus kinase inhibitors are under investigation in phase II and III trials.Furthermore, the management of IBD has evolved from targeting control of symptoms to suppression of mucosal inflammation. This shift in thinking has been accompanied by the early use of highly effective therapy in poor prognosis patients, accelerated treatment escalation and utilization of a treat to target paradigm approach, and adoption of therapeutic drug monitoring.

Summary

The treatment landscape for IBD is rapidly evolving with the recent approval of novel biologics as well as several other agents in late phase of clinical development. Moreover, we have started to use agents more intelligently with a focus on risk stratification and early use of highly effective therapy in high-risk patients, treat to target using patient-reported outcomes (PROs), biomarkers, endoscopy, and therapeutic drug monitoring.
  相似文献   
995.

Background and Aims

Various prognostic scores are available for predicting outcome in acute-on-chronic liver failure (ACLF). We compared the available prognostic models as predictors of outcome in alcohol-related ACLF patients.

Methods

All consecutive patients with alcohol-related ACLF were included. At admission, prognostic indices-acute physiology and chronic health evaluation score (APACHE II), model for end-stage liver disease (MELD), MELD-Na, Maddrey’s discriminant function (DF), age-bilirubin-INR-creatinine (ABIC), and Chronic Liver Failure Consortium (CLIF-C) ACLF score (CLIF-C ACLF) score were calculated. Receiver operator characteristic (ROC) curves were plotted for all prognostic scores with in-hospital, 90-day, and 1-year mortality as outcome.

Results

Of the 171 patients, 170 were males, and grade 1 ACLF in 20 (11.7%), grade 2 in 52 (30.4%), and grade 3 in 99 (57.9%) patients. One hundred and nineteen (69.6%) died in-hospital. The median (IQR) Maddrey’s score, MELD, MELD-Na, ABIC, APACHE II, and CLIF-C ACLF were 87.8 (66.5–123.0), 33.1 (27.6–40.0), 34.4 (29.5–40.0), 8.5 (7.3–9.6), 15 (12–21), and 51.1 (44.1–56.4), respectively. On multivariate Cox regression analysis, independent predictors of in-hospital outcome were presence of hepatic encephalopathy (early HR, 2.078; 95%CI, 1.173–3.682, p?=?0.012 and advanced, HR, 2.330; 95% CI, 1.270–4.276, p?=?0.006), elevated serum creatinine (HR, 1.140; 95% CI, 1.023–1.270, p?=?0.018), and infection at admission (HR, 1.874; 95% CI, 1.160–23.029, p?=?0.010). On comparison of ROC curves, APACHE II and CLIF-C ACLF AUROC were significantly higher than MELD, MELD-Na, DF, and ABIC (p?<?0.05) for predicting in-hospital, 90-day, and 1-year mortality. The AUROC was highest for APACHE II followed by CLIF-C ACLF (Hanley and McNeil, p?=?0.660).

Conclusions

Alcohol-related ACLF has high in-hospital mortality. Among the available prognostic scores, CLIF-C ACLF and APACHE II perform best.
  相似文献   
996.

Purpose

Germline mutations in several genes confer a relevant lifetime risk of gastric cancer. In this context, an increasing involvement of a surgeon can be seen, mainly with the question of performing a prophylactic operation.

Methods

Patients with hereditary tumor syndromes predisposing for gastric cancer who received care leading to prophylactic total gastrectomy in our Center for Hereditary Tumor Syndromes were analyzed. For each patient, the multidisciplinary decision-making process, the perioperative course, and the histopathologic findings were assessed. Short-term morbidity was evaluated based on the medical reports.

Results

The analysis includes nine patients (six female, three male) with a median age of 41.6 (range 23–60) years. Indication for prophylactic total gastrectomy was based on family history and genetic analysis (eight patients with a germline mutation of the CDH1 gene and one patient with a SMAD4 mutation). Removal of the entire gastric mucosa was documented intraoperatively by fresh frozen section examination. Extended (DII) lymphadenectomy was performed in four patients. Histopathologic examination of gastrectomy specimens revealed six patients (6/9, 67 %) with multifocal signet ring cell carcinomas. In our series, prophylactic total gastrectomy was a safe procedure without mortality and low morbidity.

Conclusions

Patients with hereditary syndromes predisposing for gastric cancer should be evaluated for this curative procedure in a specialized center. Further research is necessary, and the implementation of nationwide registers including patients with prophylactic gastrointestinal operations due to hereditary tumor syndrome is advisable.
  相似文献   
997.
The aim of this study was to evaluate oxidative stress markers and it relations to endothelial damage as risk factor for thrombosis in patients with primary (PAPS) and secondary (SAPS) antiphospholipid syndrome (APS) in correlation to traditional risk factors. Flow-mediated (FMD) and nitroglycerine (NMD)-induced dilation of the brachial artery were studied in 140 APS patients (90 PAPS, 50 SAPS) and 40 controls matched by age, sex, and conventional risk factors for atherosclerosis. Markers of oxidative stress, lipid hydroperoxydes (LOOH), advanced oxidation protein products (AOPP), total sulfhydryl groups (tSHG), and paraoxonase 1 activity (PON1) were determined by spectrophotometric method. Oxidative stress dominates in APS patients. LOOH and AOPP correlate to lipid fractions (p < 0.05), unlike PON1, tSHG that correlated to antiphospholipid antibody positivity (p < 0.05). FMD was lower in APS patients comparing to controls (p < 0.001). Cholesterol is independent variable for FMD impairment in control group (p = 0.011); LOOH in PAPS (p = 0.004); LOOH, aCL, and triglycerides in SAPS patients (p = 0.009, p = 0.049, and p = 0.012, respectively). Combined predictive of aCL and LOOH is better for FMD impairment than LOOH alone in both PAPS and SAPS patients (AUC 0.727, p = 0.001, 95 % CI 0.616–0.837 and AUC 0.824, p?0.001, 95 % CI 0.690–0.957, respectively). Lipid peroxidation is independent predictor for endothelial dysfunction in APS patients. We demonstrated synergistic effect of aCL and LOOH as risk for endothelial impairment in both PAPS and SAPS patients.  相似文献   
998.

Background

Adenosine kinase deficiency is a recently described defect affecting methionine metabolism with a severe clinical phenotype comprising mainly neurological and hepatic impairment and dysmorphism.

Methods

Clinical data of 11 additional patients from eight families with adenosine kinase deficiency were gathered through a retrospective questionnaire. Two liver biopsies of one patient were systematically evaluated.

Results

The main clinical symptoms are mild to severe liver dysfunction with neonatal onset, muscular hypotonia, global developmental retardation and dysmorphism (especially frontal bossing). Hepatic involvement is not a constant finding. Most patients have epilepsy and recurrent hypoglycemia due to hyperinsulinism. Major biochemical findings are intermittent hypermethioninemia, increased S-adenosylmethionine and S-adenosylhomocysteine in plasma and increased adenosine in urine. S-adenosylmethionine and S-adenosylhomocysteine are the most reliable biochemical markers. The major histological finding was pronounced microvesicular hepatic steatosis. Therapeutic trials with a methionine restricted diet indicate a potential beneficial effect on biochemical and clinical parameters in four patients and hyperinsulinism was responsive to diazoxide in two patients.

Conclusion

Adenosine kinase deficiency is a severe inborn error at the cross-road of methionine and adenosine metabolism that mainly causes dysmorphism, brain and liver symptoms, but also recurrent hypoglycemia. The clinical phenotype varies from an exclusively neurological to a multi-organ manifestation. Methionine-restricted diet should be considered as a therapeutic option.
  相似文献   
999.
Background and Aims It is a commonly held notion that patients with cirrhosis do not suffer from deep vein thrombosis (DVT) or pulmonary embolism (PE) because they are naturally anticoagulated. However, to date, no studies have been carried out that objectively address this issue. We conducted a study to examine the relationship between cirrhosis and DVT/PE events. Methods A case–control study of patients seen at a tertiary care hospital was performed. Cases were hospitalized patients with biopsy and/or imaging plus clinical evidence of cirrhosis. Well-matched patients with no known evidence of cirrhosis served as controls. The DVT/PE events were identified by the international classification of disease-9 (ICD-9) codes and confirmed with radiographic/nuclear imaging. The Charlson Index was calculated to determine the comorbidity. The incidence of DVT/PE in cirrhotic patients was also compared to patients with chronic kidney disease (CKD), congestive heart failure (CHF), and solid organ cancers. Results This study consisted of 963 cirrhotics and 12,405 controls. Both the incidence of DVT/PE (1.8 vs. 0.9%, P = 0.007) and Charlson Index scores (3.2 ± 1.8 vs. 0.9 ± 1.5, P < 0.001) were higher in cirrhotics than in the controls. However, in the multivariate analysis, the presence of cirrhosis was not associated with DVT/PE [odds ratio (OR) 0.87, P = 0.06]. Partial thromboplastin time (PTT; OR 0.88, P = 0.04) and serum albumin (OR 0.47, P = 0.03) were the independent predictors of DVT/PE. The incidence of DVT/PE in cirrhotics (1.8%) was lower than that in patients with other medical illnesses: 7.1% in CKD, 7.8% in CHF, and 6.1% in cancers. Conclusion Patients with cirrhosis do not have a lower risk of DVT/PE than non-cirrhotic controls without other significant co-morbidities, such as CHF, CKD, and solid organ cancers. Partial thromboplastin time and serum albumin were found to be independently predictive of DVT/PE in cirrhotic patients.  相似文献   
1000.
Congenital anomalies of the inferior vena cava such as absence or atresia are uncommon vascular defects and result from aberrant development during embryogenesis. We report a case of a young female patient affected by proximal deep venous thrombosis (DVT) complicated by liver and pulmonary embolism; subsequent extensive evaluation revealed the congenital absence of infrarenal inferior vena cava, with emboli probably occurring through collateral veins. Accordingly, in young patients with idiopathic DVT of the lower extremities and pelvic veins, the presence of inferior vena cava abnormalities should always be considered and investigated, together with classic coagulation factors, as a factor predisposing to thromboembolic complications.  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