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   9673篇
  免费   601篇
  国内免费   13篇
耳鼻咽喉   72篇
儿科学   240篇
妇产科学   178篇
基础医学   1403篇
口腔科学   152篇
临床医学   1006篇
内科学   1930篇
皮肤病学   146篇
神经病学   959篇
特种医学   370篇
外国民族医学   26篇
外科学   1526篇
综合类   72篇
一般理论   2篇
预防医学   650篇
眼科学   210篇
药学   608篇
中国医学   21篇
肿瘤学   716篇
  2022年   64篇
  2021年   128篇
  2020年   96篇
  2019年   144篇
  2018年   171篇
  2017年   147篇
  2016年   169篇
  2015年   175篇
  2014年   259篇
  2013年   395篇
  2012年   444篇
  2011年   504篇
  2010年   300篇
  2009年   263篇
  2008年   448篇
  2007年   422篇
  2006年   410篇
  2005年   418篇
  2004年   395篇
  2003年   363篇
  2002年   407篇
  2001年   306篇
  2000年   304篇
  1999年   267篇
  1998年   134篇
  1997年   103篇
  1996年   79篇
  1995年   89篇
  1994年   55篇
  1993年   58篇
  1992年   174篇
  1991年   169篇
  1990年   172篇
  1989年   147篇
  1988年   144篇
  1987年   128篇
  1986年   131篇
  1985年   134篇
  1984年   101篇
  1983年   77篇
  1982年   62篇
  1981年   60篇
  1979年   68篇
  1978年   69篇
  1977年   64篇
  1976年   60篇
  1974年   72篇
  1973年   58篇
  1972年   52篇
  1969年   53篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
Intratumor heterogeneity is a main cause of the dismal prognosis of glioblastoma (GBM). Yet, there remains a lack of a uniform assessment of the degree of heterogeneity. With a multiscale approach, we addressed the hypothesis that intratumor heterogeneity exists on different levels comprising traditional regional analyses, but also innovative methods including computer-assisted analysis of tumor morphology combined with epigenomic data. With this aim, 157 biopsies of 37 patients with therapy-naive IDH-wildtype GBM were analyzed regarding the intratumor variance of protein expression of glial marker GFAP, microglia marker Iba1 and proliferation marker Mib1. Hematoxylin and eosin stained slides were evaluated for tumor vascularization. For the estimation of pixel intensity and nuclear profiling, automated analysis was used. Additionally, DNA methylation profiling was conducted separately for the single biopsies. Scoring systems were established to integrate several parameters into one score for the four examined modalities of heterogeneity (regional, cellular, pixel-level and epigenomic). As a result, we could show that heterogeneity was detected in all four modalities. Furthermore, for the regional, cellular and epigenomic level, we confirmed the results of earlier studies stating that a higher degree of heterogeneity is associated with poorer overall survival. To integrate all modalities into one score, we designed a predictor of longer survival, which showed a highly significant separation regarding the OS. In conclusion, multiscale intratumor heterogeneity exists in glioblastoma and its degree has an impact on overall survival. In future studies, the implementation of a broadly feasible heterogeneity index should be considered.  相似文献   
2.
3.
An association between juvenile xanthogranuloma (JXG), neurofibromatosis type 1 (NF1), and juvenile myelomonocytic leukemia (JMML) has been described in the literature but has only been documented in approximately 20 cases. We diagnosed a patient with NF1 at 25 months of age, before any cutaneous stigmata of this disease had appeared, because we decided to screen for the NF1 gene mutation because of his presentation with multiple JXGs and moderate macrocephaly (2.5 standard deviations) at 9 months of age and JMML diagnosed at 20 months of age. The child is well today after treatment with chemotherapy and allogenic bone marrow transplantation. With increased awareness, patients with JXG and NF1 who develop symptoms possibly related to JMML, such as paleness, skin bleeding, cough, unexplained fever, and hepatosplenomegaly, should be further evaluated. We also emphasize that multiple JXG lesions can be an early marker of NF1.  相似文献   
4.
5.
6.
BACKGROUND AND PURPOSE:Embolization of the middle meningeal artery for treatment of refractory or recurrent chronic subdural hematomas has gained momentum during the past few years. Little has been reported on the use of the n-BCA liquid embolic system for middle meningeal artery embolization. We present the technical feasibility of using diluted n-BCA for middle meningeal artery embolization.MATERIALS AND METHODS:We sought to examine the safety and technical feasibility of the diluted n-BCA liquid embolic system for middle meningeal artery embolization. Patients with chronic refractory or recurrent subdural hematomas were prospectively enrolled from September 2019 to June 2020. The primary outcome was the safety and technical feasibility of the use of diluted n-BCA for embolization of the middle meningeal artery. The secondary end point was the efficacy in reducing hematoma volume.RESULTS:A total of 16 patients were prospectively enrolled. Concomitant burr-hole craniotomies were performed in 12 of the 16 patients. Two patients required an operation following middle meningeal artery embolization for persistent symptoms. The primary end point was met in 100% of cases in which there were no intra- or postprocedural complications. Distal penetration of the middle meningeal artery branches was achieved in all the enrolled cases. A 7-day post–middle meningeal artery embolization follow-up head CT demonstrated improvement (>50% reduction in subdural hematoma volume) in 9/15 (60%) patients, with 6/15 (40%) showing an unchanged or stable subdural hematoma. At day 21, available CT scans demonstrated substantial further improvement (>75% reduction in subdural hematoma volume).CONCLUSIONS:Embolization of the middle meningeal artery using diluted n-BCA and ethiodized oil (1:6) is safe and feasible from a technical standpoint. The use of a dextrose 5% bolus improves distal penetration of the glue.

Despite traditional treatment with surgical evacuation, chronic subdural hematomas (cSDHs) tend to have an indolent course with frequent recurrences.1 In recent years, embolization of the middle meningeal artery (MMA) for treatment of refractory or recurrent cSDH has gained momentum, with recent literature showing a significant reduction in the size of the cSDH as well as lower rates of recurrence.2 The primary endovascular techniques used to date have involved the use of polyvinyl alcohol particles (PVA) and Onyx liquid embolic (ethylene-vinyl alcohol dissolved in dimethyl-sulfoxide; Medtronic). Another commonly used liquid embolic agent in the neurointerventional area is n-BCA, which is a liquid adhesive that polymerizes rapidly on contact with ionic substances and can be injected to achieve permanent vessel occlusion. The rates of polymerization and flow and the penetration depth can be modified using varying amounts of ethiodized oil as well as concurrent infusion of dextrose 5% in water (D5W) during n-BCA (Trufill, Cordis Neurovascular) injection (D5W-push technique).3 Data on the use of n-BCA as an embolic agent in cases of cSDH are extremely limited. Herein, we sought to study the safety and technical feasibility of using diluted n-BCA for embolization of the MMA for cSDHs.  相似文献   
7.
Fast CT-PRESS-based spiral chemical shift imaging at 3 Tesla.   总被引:2,自引:0,他引:2  
A new sequence is presented that combines constant-time point-resolved spectroscopy (CT-PRESS) with fast spiral chemical shift imaging. It allows the acquisition of multivoxel spectra without line splitting with a minimum total measurement time of less than 5 min for a field of view of 24 cm and a nominal 1.5x1.5-cm2 in-plane resolution. Measurements were performed with 17 CS encoding steps in t1 (Deltat1=12.8 ms) and an average echo time of 151 ms, which was determined by simulating the CT-PRESS experiment for the spin systems of glutamate (Glu) and myo-inositol (mI). Signals from N-acetyl-aspartate, total creatine, choline-containing compounds (Cho), Glu, and mI were detected in a healthy volunteer with no or only minor baseline distortions within 14 min on a 3 T MR scanner.  相似文献   
8.
Our objective was to determine the inter-examiner agreement of a simplified pelvic organ prolapse quantification (POPQ) exam and to assess its correlation with the standard POPQ exam. This study consists of two parts; both were preformed in a prospective, randomized, blinded fashion on women presenting with complaints attributed to pelvic organ support defects. The first study was done to determine the inter-examiner reliability of a simplified POPQ exam. The simplified POPQ exam is based on the POPQ with similar ordinal staging but with only four points measured instead of nine. Forty-eight women underwent exams by five different investigators. The order of exams was randomized and the examiners were blinded to the results of each other’s findings. The results of these two exams were compared using weighted kappa statistics. The second part of the study was done to determine the inter-system agreement between the simplified vs standard POPQ exam. A group of 49 women were examined by four different investigators: one using the simplified and the other using standard POPQ exams. The order of the exams was randomized and the examiners were blinded to the results of each other’s exam. Kendall’s tau-b statistics were used to determine the inter-system agreement. For the inter-examiner reliability of the POPQ exam, the average age was 60±13 years. The weighted kappa statistics for the inter-examiner reliability of the simplified prolapse classification system were 0.86 for the overall stage, 0.89 and 0.86 for the anterior and posterior vaginal walls, respectively, 0.82 for the apex/cuff, and 0.72 for the cervix. All demonstrate significant agreement. For the inter-system association between the simplified POPQ and standard POPQ, the average age was 61±15 year. The Kendall’s tau-b value for overall stage was 0.90, 0.83, and 0.87 for the anterior and posterior walls respectively, and 0.78 for the cuff/apex and 0.98 for the cervix. There is good inter-examiner agreement of a simplified POPQ classification system and it appears to have good inter-system association with the POPQ.IUGA Standardization of Terminology Committee members: Robert Freeman MD (chairman), Steven Swift, Eckhard Petri MD, Richard J. Scotti MD, and Peter Dwyer MD.  相似文献   
9.
Sonoelasticity imaging of prostate cancer: in vitro results   总被引:2,自引:0,他引:2  
  相似文献   
10.
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