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   1593784篇
  免费   133615篇
  国内免费   2576篇
耳鼻咽喉   21651篇
儿科学   52858篇
妇产科学   46233篇
基础医学   226241篇
口腔科学   47222篇
临床医学   140220篇
内科学   312878篇
皮肤病学   34075篇
神经病学   129449篇
特种医学   64719篇
外国民族医学   474篇
外科学   243852篇
综合类   39680篇
现状与发展   3篇
一般理论   545篇
预防医学   122131篇
眼科学   36499篇
药学   121276篇
  2篇
中国医学   2887篇
肿瘤学   87080篇
  2018年   14836篇
  2016年   12974篇
  2015年   15097篇
  2014年   20732篇
  2013年   31447篇
  2012年   42709篇
  2011年   44894篇
  2010年   26427篇
  2009年   25381篇
  2008年   43131篇
  2007年   45387篇
  2006年   46212篇
  2005年   44831篇
  2004年   44249篇
  2003年   42197篇
  2002年   41338篇
  2001年   75711篇
  2000年   78281篇
  1999年   66092篇
  1998年   16747篇
  1997年   15362篇
  1996年   15298篇
  1995年   15972篇
  1994年   15017篇
  1993年   14174篇
  1992年   55445篇
  1991年   53817篇
  1990年   52602篇
  1989年   50876篇
  1988年   47267篇
  1987年   46600篇
  1986年   44313篇
  1985年   42889篇
  1984年   32024篇
  1983年   27553篇
  1982年   16102篇
  1981年   14383篇
  1980年   13507篇
  1979年   30435篇
  1978年   21034篇
  1977年   17706篇
  1976年   16658篇
  1975年   17529篇
  1974年   21466篇
  1973年   20655篇
  1972年   18855篇
  1971年   17763篇
  1970年   16280篇
  1969年   15274篇
  1968年   13954篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
ObjectivesTo identify factors associated with 30-day all-cause readmission rates in surgical patients discharged to skilled nursing facilities (SNFs), and derive and validate a risk score.DesignRetrospective cohort.Setting and participantsPatients admitted to 1 tertiary hospital's surgical services between January 1, 2011, and December 31, 2014 and subsequently discharged to 110 SNFs within a 25-mile radius of the hospital. The first 2 years were used for the derivation set and the last 2 for validation.MethodsData were collected on 30-day all cause readmissions, patient demographics, procedure and surgical service, comorbidities, laboratory tests, and prior health care utilization. Multivariate regression was used to identify risk factors for readmission.ResultsDuring the study period, 2405 surgical patients were discharged to 110 SNFs, and 519 (21.6%) of these patients experienced readmission within 30 days. In a multivariable regression model, hospital length of stay [odds ratio (OR) per day: 1.03, 95% confidence interval (CI) 1.02-1.04], number of hospitalizations in past year (OR 1.24 per hospitalization, 95% CI 1.18-1.31), nonelective surgery (OR 1.33, 95% CI 1.18-1.65), low-risk service (orthopedic/spine service) (OR 0.32, 95% CI 0.25-0.42), and intermediate-risk service (cardiothoracic surgery/urology/gynecology/ear, nose, throat) (OR 0.69, 95% CI 0.53-0.88) were associated with all-cause readmissions. The model had a C index of 0.71 in the validation set. Using the following risk score [0.8 × (hospital length of stay) + 7 × (number of hospitalizations in past year) +10 for nonelective surgery, +36 for high-risk surgery, and +20 for intermediate-risk surgery], a score of >40 identified patients at high risk of 30-day readmission (35.8% vs 12.6%, P < .001).Conclusions/ImplicationsAmong surgical patients discharged to an SNF, a simple risk score with 4 parameters can accurately predict the risk of 30-day readmission.  相似文献   
102.
103.
104.
105.
106.
Willeke  V. M.  Anderson  M. P.  Mahadevan  A.  Rojas  R.  Bhadelia  R.  Thomas  A. J.  Kasper  E. M. 《Journal of neuro-oncology》2020,147(2):247-260
Purpose

Epstein Barr virus (EBV)-associated smooth muscle tumors (SMT) in the central nervous system are rare tumors. EBV-associated SMT mainly occur in patient with compromised immune status. We report on a case of a HIV positive patient, who developed multiple EBV-SMTs, intracranially and in the spine. We systematically review the literature on the topic.

Case report

A 46 years old female with HIV was imaged for complaints of headaches for 2 years, when an intracranial lesion was found. The patient was followed with sequential MRI scans before an excision was performed 5 years later. Pathology revealed an EBV-associated SMT. Multiple other lesions appearing in the brain and in the spine over years were treated by stereotactic radiosurgery or by surgery. At the time of this report, the patient is alive under HARRT treatment without recurrence.

Methods

A systematic PRISMA guided literature research was conducted on the topic reviewing multiple databases for EBV-associated SMT located in brain or spine. We identified 52 patients from the literature and performed a pooled analysis.

Results

All patients in this cohort except one were immuno-suppressed from HIV, post-transplant therapy or because of CIS. Female predominance and a median age of 35 years was identified as was frequent multifocality. Therapeutic strategies varied but were mostly multidisciplinary with surgery.

Conclusion

Based on our results, EBV-associated SMT should be included in the differential diagnosis of intracranial lesions mimicking meningiomas in immuno-suppressed patients. Stereotactic radiosurgery can be offered as an alternate treatment option for suitable lesions. Long-term surveillance via MRI scanning is recommended for follow up.

  相似文献   
107.
Medulloblastoma (MB) is the most common and deadliest brain tumor in children. Proline-, glutamic acid-, and leucine-rich protein 1 (PELP1) is a scaffolding protein and its oncogenic signaling is implicated in the progression of several cancers. However, the role of PELP1 in the progression of MB remains unknown. The objective of this study is to examine the role of PELP1 in the progression of MB. Immunohistochemical analysis of MB tissue microarrays revealed that PELP1 is overexpressed in the MB specimens compared to normal brain. Knockdown of PELP1 reduced cell proliferation, cell survival, and cell invasion of MB cell lines. The RNA-sequencing analysis revealed that PELP1 knockdown significantly downregulated the pathways related to inflammation and extracellular matrix. Gene set enrichment analysis confirmed that the PELP1-regulated genes were negatively correlated with nuclear factor-κB (NF-κB), extracellular matrix, and angiogenesis gene sets. Interestingly, PELP1 knockdown reduced the expression of NF-κB target genes, NF-κB reporter activity, and inhibited the nuclear translocation of p65. Importantly, the knockdown of PELP1 significantly reduced in vivo MB progression in orthotopic models and improved the overall mice survival. Collectively, these results suggest that PELP1 could be a novel target for therapeutic intervention in MB.  相似文献   
108.
109.
The high expression of brain and acute leukemia, cytoplasmic (BAALC) and ETS-related gene (ERG) has been reported to influence the outcome in acute myeloid leukemia (AML), but due to limited prospective studies, their role as prognostic factors is unclear. At diagnosis, the prognostic value of BAALC and ERG expression with respect to other cytogenetic and molecular markers was analyzed in 149 AML patients. Patients were divided into quartiles which resulted in the formation of four groups (G1–G4) based on expression values of BAALC and ERG and clinical response defined across groups. Groups with similar survival probabilities were merged together and categorized subsequently as high versus low expressers. Patients with high BAALC and ERG expression had significantly lower overall survival (OS; BAALC: p = 0.001 at 5 years 29.4% vs. 69.8%; ERG: p < 0.0001 at 5 years 4% vs. 50.4%) and disease-free survival (BAALC: p = 0.001 at 5 years 19.5% vs. 69.8%; ERG: p < 0.0001 at 5 years 4.2% vs. 47%). Patients were further stratified combining BAALC and ERG expression in an integrative prognostic risk score (IPRS). After a median follow-up of 54 months (95% CI 45–63 months) among survivors, IPRS for high versus low expressers was a significant predictor for OS (BAALC + ERG: 4% vs. 71.6%, p < 0.0001) and DFS (BAALC + ERG: 4.5% vs. 74.1%, p < 0.0001). In a multivariate model, IPRS of BAALC + ERG expression retained prognostic significance for OS (hazard ratio [HR] 2.96, 95%CI 1.91–4.59, p < 0.001) and DFS (HR 3.61, 95%CI 2.26–5.76, p < 0.001).  相似文献   
110.
Morbidity and mortality among children is usually the result of trauma. Because a child’s face is retruded relative to the protecting skull, has a thicker layer of adipose tissue, more elastic bones, flexible sutures lines, the presence of tooth buds within the jaws, and the lack of pneumatisation of the sinuses, the facial bones fracture less commonly than in adults. Our aim was to assess the patterns of such fractures in children who presented to the department of Oral and Maxillofacial Surgery, King Edward Medical University/Mayo Hospital Lahore, Pakistan. All 535 eligible children between the ages of 1-16 years who presented during the two years December 2009 - December 2011 were included in the study. Facial fractures were diagnosed by clinical examination, plain radiographs, and computed tomography, and the pattern of fractures of the facial bones including the frontal bone, orbital bones, maxilla, zygoma, naso-orbito-ethmoidal complex, mandible, and dentoalveolar region was documented. The male:female ratio was 2:1 with 369 male (70%) and 166 female (31%) patients. Fall was the cause in 212 (39%), and in 167 (31%) it was road traffic accidents, while sports were the cause in 135 (25%). The naso-orboto-ethmoid complex was fractured in 37 cases (7%) while 104 children (19%) presented with isolated fractures of the zygomatic bone. The maxilla was fractured in 195 cases (36%), the mandible in 380 (71%), and dentoalveolar trauma was the cause in 256 (50%). The mandible was the bone that was most often fractured (mostly in boys and usually as a result of falls during summer vacations), with the peak occurring in those aged 8-12 years.  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