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   1343篇
  免费   68篇
  国内免费   1篇
耳鼻咽喉   10篇
儿科学   26篇
妇产科学   42篇
基础医学   224篇
口腔科学   29篇
临床医学   94篇
内科学   322篇
皮肤病学   54篇
神经病学   124篇
特种医学   56篇
外科学   143篇
综合类   23篇
预防医学   92篇
眼科学   47篇
药学   54篇
肿瘤学   72篇
  2022年   10篇
  2021年   30篇
  2020年   15篇
  2019年   22篇
  2018年   21篇
  2017年   20篇
  2016年   22篇
  2015年   26篇
  2014年   38篇
  2013年   28篇
  2012年   36篇
  2011年   52篇
  2010年   35篇
  2009年   21篇
  2008年   47篇
  2007年   36篇
  2006年   39篇
  2005年   43篇
  2004年   44篇
  2003年   56篇
  2002年   49篇
  2001年   60篇
  2000年   37篇
  1999年   49篇
  1998年   27篇
  1997年   19篇
  1996年   16篇
  1995年   12篇
  1994年   15篇
  1992年   28篇
  1991年   27篇
  1990年   29篇
  1989年   32篇
  1988年   15篇
  1987年   15篇
  1986年   19篇
  1985年   22篇
  1984年   17篇
  1983年   16篇
  1982年   10篇
  1981年   11篇
  1979年   15篇
  1976年   15篇
  1974年   15篇
  1973年   10篇
  1972年   21篇
  1971年   23篇
  1970年   10篇
  1969年   12篇
  1968年   11篇
排序方式: 共有1412条查询结果,搜索用时 15 毫秒
51.
European Journal of Clinical Microbiology & Infectious Diseases - SARS-CoV-2 antibody assays are used for epidemiological studies and for the assessment of vaccine responses in highly...  相似文献   
52.
53.
BackgroundTreatment options for metastatic osseous lesions of the proximal femur include hemiarthroplasty (HA) or total hip arthroplasty (THA) depending on lesion characteristics and patient demographics. Studies assessing short-term outcomes after HA/THA in this patient population are limited. Therefore, the purpose of this present study was to identify short-term rates of morbidity and mortality after HA/THA for pathological proximal femur fractures, as well as readmission and reoperation rates and reasons.MethodsThis study utilized a large, prospectively collected registry to identify patients who underwent HA/THA between 2011 and 2018. Patients were stratified by indication for surgery, including pathological fracture, nonpathological fracture, and osteoarthritis. Baseline patient characteristics and postoperative complications were compared using bivariate and/or multivariate analysis.ResultsIn total, 883 patients undergoing HA/THA for a pathological fracture were identified. Relative to an osteoarthritis cohort, these patients tended to be older, had a lower body mass index, and had significantly more preoperative comorbidities. These patients had high rates of total complications (13.93%), including thirty-day mortality (3.29%), unplanned return to the operating room (4.98%), and pulmonary complications (3.85%). Patients with pathological fracture had a longer operative duration relative to osteoarthritis and nonpathological cohorts (+27 and +25 minutes, respectively), despite having high rates of HAs performed.ConclusionPatients undergoing hip arthroplasty for pathologic proximal femur fracture have increased morbidity and mortality relative to an osteoarthritis cohort. However, patients with a pathological fracture have similar rates of morbidity and mortality when compared with a nonpathological fracture cohort, but did experience higher rates of perioperative blood transfusion and unplanned readmissions.Level of EvidenceIII.  相似文献   
54.

Background Context

Negative beliefs are known to influence treatment outcome in patients with spine pain (SP). The impact of positive beliefs is less clear.

Purpose

We aimed to assess the influence of positive and negative beliefs on baseline and treatment responses in patients with SP.

Study Design/Setting

A retrospective cross-sectional and longitudinal analysis of prospectively collected data of outpatient physical therapy patients with SP was carried out. Questionnaires administered before and during treatment included the STarT Back distress scale (negative beliefs), and expectation and self-efficacy questions (positive beliefs).

Patient Sample

Patients with SP with a baseline assessment and follow-up assessment comprised the study sample.

Outcome Measure

Perceived disability was measured using the Oswestry Disability Index (ODI) or the Neck Disability Index (NDI). A clinical meaningful change (minimum clinically important difference [MCID]) was defined as decrease in ODI or NDI of ≥30%.

Methods

We used the Akaike Information Criterion from the first imputed dataset of the prediction model to select predictor variables. Prediction models were fitted to the outcome variables.

Results

In the cross-sectional analysis, 1,695 low back pain (LBP) episodes and 487 neck pain (NP) episodes were analyzed. STarT Back Screening Tool (SBST)-distress was positively associated with perceived disability in both LBP (beta 2.31, 95% confidence interval [CI] 1.75–2.88) and NP (beta 2.57, 95% CI 1.47–3.67). Lower self-efficacy was negatively associated with more perceived disability for LBP (beta 0.50, 95% CI 0.29–0.72) but not for NP, whereas less positive expectations was associated with more perceived disability in NP (beta 0.57, 95% CI 0.02–1.12) but not in LBP. In the longitudinal analysis, 607 LBP episodes (36%) and 176 (36%) NP episodes were included. SBST-distress did not predict treatment outcome in spine patients. In LBP, patients with a lower positive expectation were less likely to experience an MCID in perceived disability (odds ratio [OR] per point increase 0.89, 95% CI 0.83–0.96), and there was a similar trend in NP (OR per point increase 0.90, 95% CI 0.79–1.03). In patients with LBP, lower self-efficacy at baseline was associated with a higher likelihood that an MCID was achieved (OR per point increase 1.09, 95% CI 1.01–1.19). In NP, self-efficacy was not included in the final model.

Conclusions

Our study demonstrates that both negative and positive beliefs are associated with perceptions of disability. However, in this study, only positive beliefs were associated with treatment outcome.  相似文献   
55.
56.
Clinical and biochemical correlates of starting "daily" hemodialysis.   总被引:7,自引:0,他引:7  
BACKGROUND: Daily hemodialysis has been proposed to improve outcomes for patients with end-stage renal disease. There has been increasing evidence that daily hemodialysis might have potential advantages over intermittent dialysis. However, despite these potential advantages, daily hemodialysis is infrequently used in the United States, and published accounts on the technique are few. METHODS: We describe patient outcomes after increasing their hemodialysis frequency from three to six times per week in a cohort of 72 patients treated at nine centers during 1972 to 1996. Analyses of predialysis blood pressure and laboratory parameters from 6 months before until 12 months after starting frequent hemodialysis used a repeated-measures statistical technique. RESULTS: Predialysis systolic and diastolic blood pressures fell by 7 and 4 mm Hg, respectively, after starting frequent hemodialysis (P = 0.02). Reductions were greatest among patients being treated with antihypertensive medications, despite a reduction in their dosage of medications. Postdialysis weight fell by 1.0% within one month of starting frequent hemodialysis and improved control of hypertension. After the initial drop, postdialysis weight increased at a rate of 0.85 kg per six months. Serum albumin rose by 0.29 g/dl (P < 0.001) between months 1 to 12 of treatment with daily hemodialysis. Hematocrit rose by 3.0 percentage points (P = 0.02) among patients (N = 56) not treated with erythropoietin during this period. Two years after the start of daily hemodialysis, Kaplan-Meier analyses showed a patient survival of 93%, a technique survival of 77%, and an arteriovenous fistula patency of 92%. Vascular access patency was excellent despite more frequent use of the access. CONCLUSIONS: These results suggest that in certain patients, daily hemodialysis might have advantages over three times per week hemodialysis.  相似文献   
57.
Variation in gene content has been hypothesized to be the primary mode of adaptive evolution in microorganisms; however, very little is known about the spatial and temporal distribution of variable genes. Through population-scale comparative genomics of 7 Sulfolobus islandicus genomes from 3 locations, we demonstrate the biogeographical structure of the pan-genome of this species, with no evidence of gene flow between geographically isolated populations. The evolutionary independence of each population allowed us to assess genome dynamics over very recent evolutionary time, beginning ≈910,000 years ago. On this time scale, genome variation largely consists of recent strain-specific integration of mobile elements. Localized sectors of parallel gene loss are identified; however, the balance between the gain and loss of genetic material suggests that S. islandicus genomes acquire material slowly over time, primarily from closely related Sulfolobus species. Examination of the genome dynamics through population genomics in S. islandicus exposes the process of allopatric speciation in thermophilic Archaea and brings us closer to a generalized framework for understanding microbial genome evolution in a spatial context.  相似文献   
58.
59.
Inflammatory cascades induced by spinal cord injuries (SCI) are localized in the white matter, a recognized neural stem‐ and progenitor‐cell (NSPC) niche of the adult spinal cord. Chemokines, as integrators of these processes, might also be important determinants of this NSPC niche. CCL3/CCR1, CCL2/CCR2, and SDF‐1α/CXCR4 were analyzed in the ventrolateral white matter after force defined thoracic SCI: Immunoreactivity (IR) density levels were measured 2 d, 7 d, 14 d, and 42 d on cervical (C 5), thoracic (T 5), and lumbar (L 5) levels. On day post operation (DPO) 42, chemokine inductions were further evaluated by real‐time RT‐PCR and Western blot analyses. Cellular phenotypes were confirmed by double labeling with markers for major cell types and NSPCs (nestin, Musashi‐1, NG2, 3CB2, BLBP). Mitotic profiles were investigated in parallel by BrdU labeling. After lesion, chemokines were induced in the ventrolateral white matter on IR‐, mRNA‐, and protein‐level. IR was generally more pronounced after severe lesions, with soaring increases of CCL2/CCR2 and continuous elevations of CCL3/CCR1. SDF‐1α and CXCR4 IR induction was focused on thoracic levels. Chemokines/‐receptors were co‐expressed with astroglial, oligodendroglial markers, nestin, 3CB2 and BLBP by cells morphologically resembling radial glia on DPO 7 to DPO 42, and NG2 or Musashi‐1 on DPO 2 and 7. In the white matter BrdU positive cells were significantly elevated after lesion compared with sham controls on all investigated time points peaking in the early time course on thoracic level: Here, chemokines were co‐expressed by subsets of BrdU‐labeled cells. These findings suggest an important role of chemokines/‐receptors in the subpial white matter NSPC niche after SCI. © 2010 Wiley‐Liss, Inc.  相似文献   
60.
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