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   924888篇
  免费   65142篇
  国内免费   2352篇
耳鼻咽喉   12930篇
儿科学   29911篇
妇产科学   26670篇
基础医学   129636篇
口腔科学   25437篇
临床医学   76354篇
内科学   189224篇
皮肤病学   20091篇
神经病学   73562篇
特种医学   37088篇
外国民族医学   336篇
外科学   145971篇
综合类   19175篇
一般理论   262篇
预防医学   66983篇
眼科学   20964篇
药学   65544篇
中国医学   1911篇
肿瘤学   50333篇
  2019年   7363篇
  2018年   10615篇
  2017年   8067篇
  2016年   8417篇
  2015年   9338篇
  2014年   13082篇
  2013年   20572篇
  2012年   28144篇
  2011年   30134篇
  2010年   17865篇
  2009年   16514篇
  2008年   28334篇
  2007年   29995篇
  2006年   29923篇
  2005年   29477篇
  2004年   28166篇
  2003年   27209篇
  2002年   26621篇
  2001年   42209篇
  2000年   43625篇
  1999年   36625篇
  1998年   9499篇
  1997年   8570篇
  1996年   8512篇
  1995年   8460篇
  1994年   8096篇
  1993年   7606篇
  1992年   28189篇
  1991年   27006篇
  1990年   26415篇
  1989年   25354篇
  1988年   23570篇
  1987年   23170篇
  1986年   22253篇
  1985年   21171篇
  1984年   15813篇
  1983年   13477篇
  1982年   8075篇
  1979年   14574篇
  1978年   10196篇
  1977年   8614篇
  1976年   8132篇
  1975年   8950篇
  1974年   10682篇
  1973年   10177篇
  1972年   9658篇
  1971年   8914篇
  1970年   8572篇
  1969年   8016篇
  1968年   7671篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
41.
42.
ObjectiveTo assess the evolution of cost per patient/year and the cost per patient/year/drug in patients with rheumatoid arthritis (RA) receiving biological treatments. To analyze and quantify the factors influencing this evolution, such as the optimization of the biological drugs, the use of biosimilars, and official discounts and discounts obtained after negotiated procedures. In addition, to assess specific clinical parameters of disease activity in these patients.MethodsRetrospective, observational study conducted in a Spanish tertiary hospital. Adult patients diagnosed with RA under treatment from 2009 to 2017 were included.Results320, 270 and 389 patients were included in 2009, 2013 and 2017, respectively. The patient/year cost decreased from 10,789€ in 2009, 7491€ in 2013 to 7116€ in 2017. In 2017, due to the established competition, discounts of 14% and 29.5% were achieved on etanercept and its biosimilar; 11.5%, 17.8%, 17.9%, 17.3% on adalimumab, certolizumab, golimumab and tocilizumab IV respectively, and 24.6% and 43.1% on infliximab and its biosimilar. The percentage of patients optimized in 2017 was 35.2%. The annual saving in 2017 was 1,288,535€ (830,000€ due to dose optimization and/or administration regimens, 249,666€ corresponding to 7.5% of the official discount and 208,868€ after negotiated procedures).ConclusionThe annual cost per patient in RA decreased considerably due to different factors, such as discounts on the purchase of drugs due to official discounts and negotiated procedures, together with the optimization of therapies, the latter being the factor that contributed most to this decrease.  相似文献   
43.
44.
Sport Sciences for Health - In the Tokyo 2021 Olympics, combat sports (boxing, fencing, judo, karate, taekwondo, and wrestling) will play a leading role, constituting approximately 22% of all the...  相似文献   
45.
IntroductionOrgan-based tube current modulation (OBTCM) is designed for anterior dose reduction in Computed Tomography (CT). The purpose was to assess dose reduction capability in chest CT using three organ dose modulation systems at different kVp settings. Furthermore, noise, diagnostic image quality and tumour detection was assessed.MethodsA Lungman phantom was scanned with and without OBTCM at 80–135/140 kVp using three CT scanners; Canon Aquillion Prime, GE Revolution CT and Siemens Somatom Flash. Thermo-luminescent dosimeters were attached to the phantom surface and all scans were repeated five times. Image noise was measured in three ROIs at the level of the carina. Three observers visually scored the images using a fivestep scale. A Wilcoxon Signed-Rank test was used for statistical analysis of differences.ResultsUsing the GE revolution CT scanner, dose reductions between 1.10 mSv (12%) and 1.56 mSv (24%) (p < 0.01) were found in the anterior segment and no differences posteriorly and laterally. Total dose reductions between 0.64 (8%) and 0.91 mSv (13%) were found across kVp levels (p < 0.00001). Maximum noise increase with OBTCM was 0.8 HU. With the Canon system, anterior dose reductions of 6–10% and total dose reduction of 0.74–0.76 mSv across kVp levels (p < 0.001) were found with a maximum noise increase of 1.1 HU. For the Siemens system, dose increased by 22–51% anteriorly; except at 100 kVp where no dose difference was found. Noise decreased by 1 to 1.5 HU.ConclusionOrgan based tube current modulation is capable of anterior and total dose reduction with minimal loss of image quality in vendors that do not increase posterior dose.Implications for practiceThis research highlights the importance of being familiar with dose reduction technologies.  相似文献   
46.
47.
IntroductionThe main challenge of Parkinson's disease in women of childbearing age is managing symptoms and drugs during pregnancy and breastfeeding. The increase in the age at which women are having children makes it likely that these pregnancies will become more common in future.ObjectivesThis study aims to define the clinical characteristics of women of childbearing age with Parkinson's disease and the factors affecting their lives, and to establish a series of guidelines for managing pregnancy in these patients.ResultsThis consensus document was developed through an exhaustive literature search and a discussion of the available evidence by a group of movement disorder experts from the Spanish Society of Neurology.ConclusionsParkinson's disease affects all aspects of sexual and reproductive health in women of childbearing age. Pregnancy should be well planned to minimise teratogenic risk. A multidisciplinary approach should be adopted in the management of these patients in order to take all relevant considerations into account.  相似文献   
48.
49.
IntroductionRealignment knee osteotomy relies on accurate preoperative assessment of coronal alignment. Weightbearing (WB) ‘long-leg’ (LL) radiographs are the accepted gold-standard investigation, though in practice standard knee radiographs (short leg; SL) and non-weightbearing (NWB) cross-sectional imaging such as computed tomography (CT) scanograms have been used. We compare the accuracy of SL and NWB radiographs to formal LL alignment radiographs.MethodsA prospectively maintained osteotomy database was reviewed to identify the study population. All patients underwent standardised weightbearing long-leg alignment radiographs. The series was screened consecutively until 30 patients who also underwent WB SL radiographs (‘WB cohort’), and 30 with NWB SL (‘NWB cohort’) radiographs, were identified. Anatomic tibiofemoral angle was calculated by independent reviewers using a validated technique from both radiographs and contrasted.Results60 patients were identified as outlined in the study protocol. There were no differences in baseline demographics. Coronal alignment calculated from SL and LL radiographs differed significantly (median difference 2.1°, p < 0.001). Alignment values from weightbearing SL radiographs demonstrated markedly greater agreement with LL values than those from NWB radiographs (intraclass correlation coefficient 0.878 vs 0.657), with the NWB cohort also exhibiting greater outlier and extreme outlier incidence.ConclusionOur data adds to the growing evidence that SL radiographs are inadequate in the interpretation of knee alignment. In addition, we demonstrate that NWB radiographs (and by extension other NWB modalities such CT scanograms) demonstrate poorer agreement to gold-standard than WB methods. Coronal alignment of the knee cannot be reliably measured from non-weightbearing imaging modalities.Implications for practiceThough potentially useful as an adjunct, non-weightbearing cross-sectional imaging and standard knee radiographs should not be used as a proxy for formal weightbearing long-leg radiographs in osteotomy planning.  相似文献   
50.
BACKGROUND AND PURPOSE:Collateral status and thrombus length have been independently associated with functional outcome in patients with acute ischemic stroke. It has been suggested that thrombus length would influence functional outcome via interaction with the collateral circulation. We investigated the individual and combined effects of thrombus length assessed by the clot burden score and collateral status assessed by a FLAIR vascular hyperintensity–ASPECTS rating system on functional outcome (mRS).MATERIALS AND METHODS:Patients with anterior circulation acute ischemic stroke due to large-vessel occlusion from the ASTER and THRACE trials treated with endovascular thrombectomy were pooled. The clot burden score and FLAIR vascular hyperintensity score were determined on MR imaging obtained before endovascular thrombectomy. Favorable outcome was defined as an mRS score of 0–2 at 90 days. Association of the clot burden score and the FLAIR vascular hyperintensity score with favorable outcome (individual effect and interaction) was examined using logistic regression models.RESULTS:Of the 326 patients treated by endovascular thrombectomy with both the clot burden score and FLAIR vascular hyperintensity assessment, favorable outcome was observed in 165 (51%). The rate of favorable outcome increased with clot burden score (smaller clots) and FLAIR vascular hyperintensity (better collaterals) values. The association between clot burden score and functional outcome was significantly modified by the FLAIR vascular hyperintensity score, and this association was stronger in patients with good collaterals, with an adjusted OR = 6.15 (95% CI, 1.03–36.81).CONCLUSIONS:The association between the clot burden score and functional outcome varied for different collateral scores. The FLAIR vascular hyperintensity score might be a valuable prognostic factor, especially when contrast-based vascular imaging is not available.

Therapeutic reperfusion with endovascular thrombectomy (EVT) is consistently associated with a better long-term functional outcome in anterior circulation acute ischemic stroke (AIS).1 Early reperfusion is the mainstay of therapy because it strongly predicts functional outcome.2 Many factors impact clinical outcomes, including the extent of clot and collateral supply.37The clot burden score (CBS) assessed by the T2* MR imaging sequence (T2*-CBS), which was adapted from the CTA-CBS,8 has been used to assess the extent of the clot9 and has been independently associated with functional outcome in patients undergoing EVT.10Good collaterals have been related to better clinical outcome through 2 distinct mechanisms. First, collaterals are thought to contribute to prolonged penumbra sustenance.11,12 Second, good retrograde collateral filling beyond the occlusion could promote successful reperfusion by providing more access to thrombolytics at the distal end of the clot and robust collaterals dissolving clot fragments in the distal vasculature.13,14 The Highly Effective Reperfusion evaluated in Multiple Endovascular Stroke Trials (HERMES) collaboration analysis suggested a benefit with EVT across all strata of collateral circulation status;15 however, patients with poor collaterals are less likely to benefit from EVT than those with better collaterals.Most interesting, FLAIR vascular hyperintensity (FVH) on baseline MR imaging could indicate the formation of a leptomeningeal collateral circulation and serve as a prognostic marker for patients with AIS.16-18 Both collaterals and the CBS were separately associated with functional outcome in patients undergoing EVT,10,16 but their combined effect regarding clinical outcome is still poorly understood and has been assessed and quantified only with CTA or contrast-enhanced MRA in patients with AIS.14,15 Furthermore, the lack of adjustment for possible confounders because of the small number of patients with very low collateral scores might also have influenced results in these studies.The purpose of this study was to determine whether there is an association between the CBS and FVH score and whether the association between the CBS and functional outcome is modified by the FVH score for patients who were treated by EVT for large-vessel occlusion within the framework of the Contact Aspiration versus Stent Retriever for Successful Revascularization (ASTER) and the THRombectomie des Artères CErebrales (THRACE) randomized trials.19,20  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