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   4439篇
  免费   209篇
  国内免费   38篇
耳鼻咽喉   44篇
儿科学   85篇
妇产科学   183篇
基础医学   666篇
口腔科学   59篇
临床医学   460篇
内科学   1117篇
皮肤病学   52篇
神经病学   381篇
特种医学   159篇
外科学   550篇
综合类   21篇
一般理论   2篇
预防医学   203篇
眼科学   30篇
药学   317篇
中国医学   3篇
肿瘤学   354篇
  2023年   20篇
  2022年   50篇
  2021年   89篇
  2020年   51篇
  2019年   71篇
  2018年   97篇
  2017年   86篇
  2016年   73篇
  2015年   90篇
  2014年   114篇
  2013年   179篇
  2012年   327篇
  2011年   368篇
  2010年   186篇
  2009年   156篇
  2008年   327篇
  2007年   353篇
  2006年   289篇
  2005年   299篇
  2004年   319篇
  2003年   294篇
  2002年   244篇
  2001年   34篇
  2000年   27篇
  1999年   48篇
  1998年   72篇
  1997年   46篇
  1996年   52篇
  1995年   52篇
  1994年   24篇
  1993年   18篇
  1992年   26篇
  1991年   26篇
  1990年   19篇
  1989年   16篇
  1988年   11篇
  1987年   11篇
  1986年   16篇
  1985年   15篇
  1984年   11篇
  1983年   11篇
  1982年   8篇
  1981年   12篇
  1980年   3篇
  1978年   7篇
  1975年   3篇
  1974年   4篇
  1973年   3篇
  1969年   3篇
  1965年   4篇
排序方式: 共有4686条查询结果,搜索用时 15 毫秒
991.
Graefe's Archive for Clinical and Experimental Ophthalmology - Binocular visual impairment related to unilateral idiopathic epiretinal membranes (uiERM) and its association with vision-related...  相似文献   
992.
993.
994.
995.
We prospectively evaluated the performance of combined shear wave elastography (SWE) and conventional ultrasound (US) for the characterization of 89 testicular focal masses. Testes were evaluated with B-mode, color Doppler and SWE measurements, locating a region of interest on the normal and pathologic parenchyma. Thirty-seven malignant tumors (MTs), 12 burned out tumors (BOTs), 28 Leydig cell tumors (LCTs), 2 dermoid cysts and other benign lesions were included. MTs?+?BOTs exhibited more microliths and macrocalcifications compared with benign lesions (p < 10–4). LCTs manifested mostly a dominant peripheral vascularization pattern compared with other lesions. MTs?+?BOTs were stiffer compared with benign lesions (p < 2?×?10–4) but with a moderate area under the receiver operating characteristic curve (AUROC) of 80%. By focusing on LCTs versus MTs?+?BOTs, diagnostic performance led to an AUROC of 89% for the best stiffness parameter. For combined conventional US and SWE, the diagnostic performance to differentiate all benign lesions versus MTs?+?BOTs and LCTs versus MTs?+?BOTs increased to AUROCs of 93% and 98%, respectively.  相似文献   
996.
An original way to obtain fibers with special chromatic dispersion and single-mode behavior is to consider microstructured optical fibers (MOFs). These fibers present unique optical properties thanks to the high degree of freedom in the design of their geometrical structure. In this study, the first all-solid all-chalcogenide MOFs exhibiting photonic bandgap transmission have been achieved and optically characterized. The fibers are made of an As38Se62 matrix, with inclusions of Te20As30Se50 glass that shows a higher refractive index (n = 2.9). In those fibers, several transmission bands have been observed in mid infrared depending on the geometry. In addition, for the first time, propagation by photonic bandgap effect in an all-chalcogenide MOF has been observed at 3.39 µm, 9.3 µm, and 10.6 µm. The numerical simulations based on the optogeometric properties of the fibers agree well with the experimental characterizations.  相似文献   
997.
998.
999.
The primary aim of the study was to adopt QOLIBRI (quality of life after brain injury) questionnaire in a proxy version (Q-Pro), i.e., to use caregivers for comparison and to evaluate whether TBI patients’ judgment corresponds to that of their caregivers since the possible self-awareness deficit of the persons with TBI. A preliminary sample of 19 outpatients with TBI and their proxies was first evaluated with the Patient Competency Rating Scale to assess patients’ self-awareness; then they were evaluated with the QOLIBRI Patient version (Q-Pt) and a patient-centered version of the Q-Pro. Subsequently, 55 patients and their caregivers were evaluated using the patient-centered and the caregiver-centered Q-Pro versions. Q-Pt for assessing Quality of Life (QoL) after TBI, as patients’ subjective perspective and Q-Pro to assess the QoL of patients as perceived by the caregivers. The majority of patients (62.2%) showed better self-perception of QoL than their proxies; however, patients with low self-awareness were less satisfied than patients with adequate self-awareness. Low self-awareness does not impair the ability of patients with TBI to report on satisfaction with QoL as self-perceived.  相似文献   
1000.
This paper presents experimental characterization of plasmoids (fireballs) obtained by directing localized microwave power (<1 kW at 2.45 GHz) onto a silicon-based substrate in a microwave cavity. The plasmoid emerges up from the hotspot created in the solid substrate into the air within the microwave cavity. The experimental diagnostics employed for the fireball characterization in this study include measurements of microwave scattering, optical spectroscopy, small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Various characteristics of these plasmoids as dusty plasma are drawn by a theoretical analysis of the experimental observations. Aggregations of dust particles within the plasmoid are detected at nanometer and micrometer scales by both in-situ SAXS and ex-situ SEM measurements. The resemblance of these plasmoids to the natural ball-lightning (BL) phenomenon is discussed with regard to silicon nano-particle clustering and formation of slowly-oxidized silicon micro-spheres within the BL. Potential applications and practical derivatives of this study (e.g., direct conversion of solids to powders, material identification by breakdown spectroscopy (MIBS), thermite ignition, and combustion) are discussed.  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