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   1250篇
  免费   74篇
  国内免费   1篇
耳鼻咽喉   11篇
儿科学   14篇
妇产科学   9篇
基础医学   138篇
口腔科学   4篇
临床医学   110篇
内科学   389篇
皮肤病学   25篇
神经病学   119篇
特种医学   29篇
外科学   142篇
综合类   5篇
预防医学   115篇
眼科学   5篇
药学   72篇
肿瘤学   138篇
  2023年   7篇
  2022年   22篇
  2021年   57篇
  2020年   19篇
  2019年   38篇
  2018年   49篇
  2017年   28篇
  2016年   21篇
  2015年   24篇
  2014年   52篇
  2013年   67篇
  2012年   105篇
  2011年   116篇
  2010年   58篇
  2009年   55篇
  2008年   96篇
  2007年   82篇
  2006年   98篇
  2005年   75篇
  2004年   88篇
  2003年   51篇
  2002年   43篇
  2001年   6篇
  2000年   8篇
  1999年   9篇
  1998年   1篇
  1997年   6篇
  1996年   5篇
  1995年   4篇
  1994年   2篇
  1993年   3篇
  1992年   3篇
  1991年   3篇
  1990年   4篇
  1989年   2篇
  1988年   4篇
  1987年   7篇
  1985年   2篇
  1978年   1篇
  1969年   1篇
  1966年   1篇
  1965年   1篇
  1940年   1篇
排序方式: 共有1325条查询结果,搜索用时 15 毫秒
21.
Primary sclerosing cholangitis (PSC) is a common indication for liver transplantation (LT). Up to 25% of patients experience recurrence of PSC (rPSC) after LT, which is associated with significant morbidity and mortality. To date, it is not possible to predict which patients are at risk for rPSC. The aetiology of PSC is complex and is speculated to involve translocation of intestinal bacteria to the liver, because of its frequent co-occurrence with inflammatory bowel diseases (IBD). Here, we investigate whether the mucosal intestinal microbiome of PSC patients (n = 97) at time of first LT can identify those patients who will develop rPSC. 16S gene sequencing of bacterial DNA isolated from formalin-fixed paraffin-embedded biopsies showed that PSC patients with Crohn’s disease (n = 15) have a reduced microbial diversity and that inflammation of the mucosa is associated with beta-diversity changes and feature differences. No differences in alpha- or beta diversity were observed between patients with rPSC (n = 14) and without rPSC (n = 83). However, many over-represented bacterial features were detected in patients with rPSC, while surprisingly, those without recurrence of disease were characterized by an increased presence of the Gammaproteobacteria Shigella. This pilot study warrants further investigation into bacterial differences between rPSC and non-rPSC patients.  相似文献   
22.
Background contextCombined monitoring of muscle motor evoked potentials elicited by transcranial electric stimulation (TES-mMEP) and cortical somatosensory evoked potentials (cSSEPs) is safe and effective for spinal cord monitoring during scoliosis surgery. However, TES-mMEP/cSSEP is not always feasible. Predictors of feasibility would help to plan the monitoring strategy.PurposeTo identify predictors of the feasibility of TES-mMEP/cSSEP during scoliosis surgery.Study design/settingProspective cohort study in a clinical neurophysiology unit and pediatric orthopedic department of a French university hospital.Patient sampleA total of 103 children aged 2 to 19 years scheduled for scoliosis surgery.Outcome measuresFeasibility rate of intraoperative TES-mMEP/cSSEP monitoring.MethodsAll patients underwent a preoperative neurological evaluation and preoperative mMEP and cSSEP recordings at both legs. For each factor associated with feasibility, we computed sensitivity, specificity, positive predictive value (PPV), and negative predictive value. A decision tree was designed.ResultsPresence of any of the following factors was associated with 100% feasibility, 100% specificity, and 100% PPV: idiopathic scoliosis, normal preoperative neurological findings, and normal preoperative mMEP and cSSEP recordings. Feasibility was 0% in the eight patients with no recordable mMEPs or cSSEPs during preoperative testing. A decision tree involving three screening steps can be used to identify patients in whom intraoperative TES-mMEP/cSSEP is feasible.ConclusionsPreoperative neurological and neurophysiological assessments are helpful for identifying patients who can be successfully monitored by TES-mMEP/cSSEP during scoliosis surgery.  相似文献   
23.
24.
25.
The objective of this study was to evaluate the feasibility, the toxicity and the efficiency of a BFM-like treatment protocol for acute nonlymphoblastic leukemia (ANLL) of children in which mitoxantrone was substituted for conventional anthracycline. The chemotherapy called for induction (mitoxantrone, cytosine arabinoside, etoposide), consolidation (mitoxantrone, cytosine arabinoside, 6 thioguanine), followed by two intensification courses with cytosine arabinoside plus, respectively, mitoxantrone during the first and etoposide during the second courses. Maintenance therapy consisted of daily 6 thioguanine, four-weekly courses of cytosine arabinoside (s.c. daily during 4 days) and eight-weekly courses of mitoxantrone. The latter drug was pursued up to a total cumulative dose of 150 mg/sqm. Maintenance therapy was stopped at 2 years of diagnosis. Out of 108 patients, 84 (77%) achieved a complete remission, 10 died during induction of hemorrhage, sepsis or pulmonary infiltration by leukemic cells. A total of 32 relapses occurred. The median follow-up was 3.5 years. Actuarial event-free survival, disease-free survival and overall survival at 3 years as 41%, 52%, 56%;, respectively. These results compare favorably with most reported data, and cytogenetic findings appear to be the most important prognostic factor. © 1996 Wiley-Liss, Inc.  相似文献   
26.
27.
28.
29.
To identify new candidate anticancer compounds, we here report the synthesis of benzimidazole derivatives: diethyl 2,2′-(2-oxo-1H-benzo[d]imidazole-1,3(2H)-diyl) diacetate and its arylideneacetohydrazide derivatives, using ultrasonic irradiation and conventional heating. The compounds were confirmed by Nuclear magnetic resonance (NMR) (JEOL, Tokyo, Japan) and Fourier transform infrared spectroscopy (FTIR) spectroscopy (Thermoscientific, Waltham, MA, USA). The molecular structure and electronic properties of the studied compounds were predicted for the acetohydrazide hydrazones. These compounds exist as a mixture of configurational and conformational isomerism as well as amido-amidic acid tautomerism. The NMR spectral data proved the predominance of syn-E amido isomers. In addition, density functional theory (DFT) predicted stability in the gas phase and showed that syn-E amido isomers are the most stable in the presence of an electron donating group, while the anti-isomer is the most stable in the presence of electron-attracting substituents. The anticancer activity of these synthetic compounds 6a, 6b and 6c towards both colon cancer (HCT-116) and cervical cancer (HeLa) cells was examined by MTT assay and DAPI staining. The MTT assay revealed a strong antiproliferative effect against the cancer cells at low concentrations, and interestingly, no significant inhibitory action against the non-cancerous cell line, HEK-293. The IC50 values for HCT-116 were 29.5 + 4.53 µM, 57.9 + 7.01 µM and 40.6 + 5.42 µM for 6a, 6b, and 6c, respectively. The IC50 values for HeLa cells were 57.1 + 6.7 µM, 65.6 + 6.63 µM and 33.8 + 3.54 µM for 6a, 6b, and 6c, respectively. DAPI staining revealed that these synthesized benzimidazole derivatives caused apoptotic cell death in both the colon and cervical cancer cells. Thus, these synthetic compounds demonstrate encouraging anticancer activity as well as being safe for normal human cells, making them attractive candidates as anticancer agents.  相似文献   
30.

Introduction and objectives

Deeper understanding of the myocardial structure linking the morphology and function of the heart would unravel crucial knowledge for medical and surgical clinical procedures and studies. Several conceptual models of myocardial fiber organization have been proposed but the lack of an automatic and objective methodology prevented an agreement. We sought to deepen this knowledge through advanced computer graphical representations of the myocardial fiber architecture by diffusion tensor magnetic resonance imaging.

Methods

We performed automatic tractography reconstruction of unsegmented diffusion tensor magnetic resonance imaging datasets of canine heart from the public database of the Johns Hopkins University. Full-scale tractographies have been built with 200 seeds and are composed by streamlines computed on the vector field of primary eigenvectors at the diffusion tensor volumes. We also introduced a novel multiscale visualization technique in order to obtain a simplified tractography. This methodology retains the main geometric features of the fiber tracts, making it easier to decipher the main properties of the architectural organization of the heart.

Results

Output analysis of our tractographic representations showed exact correlation with low-level details of myocardial architecture, but also with the more abstract conceptualization of a continuous helical ventricular myocardial fiber array.

Conclusions

Objective analysis of myocardial architecture by an automated method, including the entire myocardium and using several 3-dimensional levels of complexity, reveals a continuous helical myocardial fiber arrangement of both right and left ventricles, supporting the anatomical model of the helical ventricular myocardial band described by F. Torrent-Guasp.  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