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   24733篇
  免费   1426篇
  国内免费   133篇
耳鼻咽喉   250篇
儿科学   635篇
妇产科学   505篇
基础医学   3692篇
口腔科学   1046篇
临床医学   2213篇
内科学   5742篇
皮肤病学   675篇
神经病学   2185篇
特种医学   565篇
外科学   2270篇
综合类   50篇
一般理论   10篇
预防医学   2347篇
眼科学   487篇
药学   1654篇
  1篇
中国医学   113篇
肿瘤学   1852篇
  2024年   112篇
  2023年   279篇
  2022年   614篇
  2021年   1045篇
  2020年   643篇
  2019年   821篇
  2018年   931篇
  2017年   645篇
  2016年   775篇
  2015年   840篇
  2014年   1114篇
  2013年   1407篇
  2012年   2200篇
  2011年   2300篇
  2010年   1206篇
  2009年   997篇
  2008年   1695篇
  2007年   1637篇
  2006年   1484篇
  2005年   1375篇
  2004年   1193篇
  2003年   1014篇
  2002年   887篇
  2001年   104篇
  2000年   69篇
  1999年   86篇
  1998年   124篇
  1997年   107篇
  1996年   86篇
  1995年   65篇
  1994年   56篇
  1993年   57篇
  1992年   42篇
  1991年   35篇
  1990年   28篇
  1989年   30篇
  1988年   25篇
  1987年   12篇
  1986年   27篇
  1985年   18篇
  1984年   26篇
  1983年   21篇
  1982年   17篇
  1981年   10篇
  1980年   3篇
  1979年   7篇
  1978年   6篇
  1977年   6篇
  1975年   2篇
  1974年   2篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Patients undergoing evaluation for solid organ transplantation (SOT) often have a history of malignancy. Although the cancer has been treated in these patients, the benefits of transplantation need to be balanced against the risk of tumor recurrence, especially in the setting of immunosuppression. Prior guidelines of when to transplant patients with a prior treated malignancy do not take in to account current staging, disease biology, or advances in cancer treatments. To develop contemporary recommendations, the American Society of Transplantation held a consensus workshop to perform a comprehensive review of current literature regarding cancer therapies, cancer stage-specific prognosis, the kinetics of cancer recurrence, and the limited data on the effects of immunosuppression on cancer-specific outcomes. This document contains prognosis based on contemporary treatment and transplant recommendations for breast, colorectal, anal, urological, gynecological, and nonsmall cell lung cancers. This conference and consensus documents aim to provide recommendations to assist in the evaluation of patients for SOT given a history of a pretransplant malignancy.  相似文献   
992.
Current guidelines recommend deferring liver transplantation (LT) in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection until clinical improvement occurs and two PCR tests collected at least 24 hours apart are negative. We report a case of an 18-year-old, previously healthy African-American woman diagnosed with COVID-19, who presents with acute liver failure (ALF) requiring urgent LT in the context of SARS-CoV-2 polymerase chain reaction (PCR) positivity. The patient was thought to have acute Wilsonian crisis on the basis of hemolytic anemia, alkaline phosphatase:bilirubin ratio <4, AST:ALT ratio >2.2, elevated serum copper, and low uric acid, although an unusual presentation of COVID-19 causing ALF could not be excluded. After meeting criteria for status 1a listing, the patient underwent successful LT, despite ongoing SARS-CoV-2 PCR positivity. Remdesivir was given immediately posttransplant, and mycophenolate mofetil was withheld initially and the SARS-CoV-2 PCR test eventually became negative. Three months following transplantation, the patient has made a near-complete recovery. This case highlights that COVID-19 with SARS-CoV-2 PCR positivity may not be an absolute contraindication for transplantation in ALF. Criteria for patient selection and timing of LT amid the COVID-19 pandemic need to be validated in future studies.  相似文献   
993.
BackgroundBreast-conserving treatment (BCT) provides better quality of life (QL) than mastectomy without reconstruction. Oncoplastic surgery (OS) encompasses a series of surgical techniques, increasing the indications for BCT, but few studies have evaluated the impact on QL in patients who undergo BCT with OS.Materials and MethodsA prospective, cross-sectional study was conducted in women who underwent BCT. We evaluated the characteristics of patients who underwent BCT with and without OS and the associated QL. QL was assessed through the EORTC QLQ-30, EORTC QLQ-BR23, and Breast Cancer Treatment Outcome Scale (BCTOS) questionnaires.ResultsA total of 300 patients underwent BCT, 72 underwent breast OS, and 37 underwent bilateral surgery. Patients who underwent OS were younger (p = 0.004), had a higher level of education (p = 0.01), had a smaller time interval since the end of treatment (p = 0.02), had tumours with greater dimensions (p = 0.003), and were more likely to receive neoadjuvant chemotherapy (p = 0.05). Based on the QL questionnaires, no difference was observed between the groups. Breast symmetry was not associated with high patient satisfaction (p = 0.55).ConclusionDespite the fact that OS was performed in patients with worse tumour conditions and in more demanding patients, OS allowed similar cosmetic results to classical BCT.  相似文献   
994.
In order to evaluate the effects of uncertainty about direction of mechanical perturbation and supra-postural task constraint on postural control, young adults had their upright stance perturbed while holding a tray in a horizontal position. Stance was perturbed by moving forward or backward a supporting platform, contrasting situations of certainty versus uncertainty of direction of displacement. Increased constraint on postural stability was imposed by a supra-postural task of equilibrating a cylinder on the tray. Performance was assessed through EMG of anterior leg muscles, angular displacement of the main joints involved in the postural reactions and displacement of the tray. Results showed that both certainty on the direction of perturbation and increased supra-postural task constraint led to decreased angular displacement of the knee and the hip. Furthermore, combination of certainty and high supra-postural task constraint produced shorter latency of muscular activation. Such postural responses were paralleled by decreased displacement of the tray. These results suggest a functional integration between the tasks, with central set priming reactive postural responses from contextual cues and increased stability demand.  相似文献   
995.

Introduction

The aim of this study was to perform a systematic review of the literature to evaluate the accuracy of FDG-PET in staging and restaging of cutaneous melanoma.

Methods

Systematic methods were used to identify, select, and evaluate the methodologic quality of the studies as well as to summarize the overall findings of sensitivity and specificity. The search strategy consisted of identifying studies published between 2000 and 2006. Inclusion criteria were studies that evaluated the diagnostic performance of FDG-PET in staging/restaging of cutaneous melanoma. The results were compared and pooled with a meta-analysis published previously that included studies published until 1999. The meta-analysis included 95% confidence intervals (CI) of sensitivity, specificity, likelihood-ratio (LR), and diagnostic-odds-ratio (DOR).

Results

The quantitative meta-analysis included 24 studies that were analysed in two groups: eight studies were included only in the regional staging analysis (group I), 13 studies were included only in the detection of distant metastases analysis (group II), and three studies were included in both analyses. Compliance with the methodologic-quality criteria was acceptable. We analysed the results of data presented in patients, lesions, basins, lymph-nodes, areas, and scans. Regarding the performance of FDG-PET in the detection of metastases, the pooled studies presented homogeneity for the negative-LR (0.15; 95% CI, 0.10–0.22) when analyzing lesions. When analyzing scans, there was global homogeneity for specificity (0.86; 95% CI, 0.77–0.92), positive-LR (5.86; 95% CI, 3.64–9.43), and DOR (37.89; 95% CI, 15.80–90.86). The pooled studies presented heterogeneity for the other items analysed. Regarding the detection of regional metastases, when analyzing lymph-nodes there was global homogeneity for specificity (0.99; 95% CI, 0.97–0.99; P?=?0.101). The meta-regression evidenced that the variable that most influenced the DOR of the different studies and that can explain the heterogeneity was the year of publication; this may be related to the evolution of PET technology and an improvement of sensitivity/specificity.

Conclusion

FDG-PET is not useful in the evaluation of regional metastases, as it does not detect microscopic disease. However, FDG-PET could be useful in the detection of distant metastases, and could suggest its utility in the management of patients with cutaneous melanoma.  相似文献   
996.
Lasers in Medical Science - Using light sources in phototherapy has presented promising results regarding several types of facial and body skin affections for centuries. The neodymium-doped yttrium...  相似文献   
997.
The genus Pestivirus comprises globally distributed members of the family Flaviviridae, which cause severe losses in livestock. The most common species of the genus are bovine viral diarrhoea virus type 1 (BVDV‐1) and type 2 (BVDV‐2), classical swine fever virus (CSFV) and border disease virus (BDV). Recently, a novel ovine pestivirus was repeatedly detected in aborted lamb foetuses on a farm located in the Brescia Province (Italy). Complete genome characterization of this isolate showed that it was highly divergent from known pestivirus species and that it was genetically closely related to CSFV. The aim of this study was to determine the serological relatedness between the identified novel pestivirus and BVDV, BDV and CSFV selected strains for which homologous serum was available, by antigenic characterization performed using cross‐neutralization assays. The serological relatedness was expressed as the coefficient of antigenic similarity (R). Both field and specific antisera raised against the ovine pestivirus neutralized the CSFV reference strain Diepholz with titres significantly higher than those specific for the BDV and BVDV strains. Furthermore, the calculated R values clearly indicated that the novel ovine pestivirus is antigenically more related to CSFV than to ruminant pestiviruses, in agreement with the results of the genomic analysis. This would have severe consequences on CSFV serology in the event of a switch to porcine hosts with implications for CSFV surveillance and porcine health management.  相似文献   
998.
999.
Despite of controls and preventive measures implemented along the food chain, infection with non‐typhoidal Salmonella (NTS) remains one of the major causes of foodborne disease worldwide. Poultry is considered one of the major sources of NTS. This has led to the implementation of monitoring and control programmes in many countries (including Spain) to ensure that in poultry flocks infection is kept to a minimum and to allow the identification and monitoring of circulating NTS strains and their antimicrobial resistance (AMR) phenotypes. Here, we investigated the information from the monitoring programme for AMR in Salmonella from poultry in Spain in 2011–2017 to assess the diversity in phenotypic resistance and to evaluate the programme's ability to detect multi‐resistance patterns and emerging strains in the animal reservoir. Data on serotype and AMR to nine antimicrobials obtained from 3,047 NTS isolates from laying hens (n = 1,060), broiler (n = 765) and turkey (n = 1,222) recovered during controls performed by the official veterinary services and food business operators were analysed using univariate and multivariate methods in order to describe host and serotype‐specific profiles. Diversity and prevalence of phenotypic resistance to all but one of the antimicrobials (colistin) were higher in NTS from broiler and turkey compared with laying hen isolates. Certain combinations of serotype and AMR pattern (resistotype) were particularly linked with certain hosts (e.g. susceptible Enteritidis with laying hens, multi‐drug resistant (MDR) Derby in turkey, MDR Kentucky in turkey and broiler). The widespread presence of certain serotype‐resistotype combinations in certain hosts/years suggested the possible expansion of MDR strains in the animal reservoir. This study demonstrates the usefulness of the analysis of data from monitoring programmes at the isolate level to detect emerging threats and suggests aspects that should be subjected to further research to identify the forces driving the expansion/dominance of certain strains in the food chain.  相似文献   
1000.

Background

Radical nephrectomy (RN) and caval thrombectomy (CT) for renal cell carcinoma, with extracorporeal circulation (ECC) and deep hypothermic circulatory arrest (DHCA) is a challenging surgical approach.

Objective

To assess peri-operative and oncologic outcomes of renal cell carcinoma patients treated with RN and CT, using ECC and DHCA.

Design, setting, and participants

We retrospectively evaluated 46 patients who underwent RN and CT using ECC and DHCA.

Surgical procedure

After retroperitoneal nodal dissection and RN, a cardiopulmonary bypass was placed and DHCA achieved. A combined approach through the abdomen and the thorax was described.

Measurements

Perioperative and long-term survival outcomes were reported.

Results and limitations

Median operative time and length of hospital stay were 545 min and 22 d. Overall, 33 patients (72%) did not require any additional interventional or surgical treatment. Thirty-day and 90-d mortality were 11% (5/46) and 15% (7/46). The 1-yr, 2-yr, and 3-yr cancer specific mortality (CSM)-free survival rates were 77%, 62%, and 56%, respectively. After stratification, according to metastatic status at diagnosis, CSM-free survival rates were significantly lower for cM1 patients compared with cM0 patients (1-yr 46% vs 93%, 2-yr 23% vs 81%, 3-yr 23% vs 73%, p < 0.01). Our study is limited by its retrospective and uncomparative nature.

Conclusions

RN with CT using ECC and DHCA is a challenging procedure which requires a dedicated multidisciplinary working team to minimise complications and maximise patients’ outcomes.

Patient summary

Patients with kidney cancer and a thrombus within the inferior vena cava, which reaches above the diaphragm, can be treated with surgery. However, this kind of surgical treatment is challenging and requires a dedicated multidisciplinary team in order to accomplish the task.  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