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   107913篇
  免费   31097篇
  国内免费   1097篇
耳鼻咽喉   2533篇
儿科学   2963篇
妇产科学   2574篇
基础医学   3800篇
口腔科学   5217篇
临床医学   27246篇
内科学   26662篇
皮肤病学   3347篇
神经病学   13117篇
特种医学   4110篇
外国民族医学   1篇
外科学   19994篇
综合类   316篇
现状与发展   40篇
一般理论   17篇
预防医学   14499篇
眼科学   2369篇
药学   1692篇
中国医学   23篇
肿瘤学   9587篇
  2024年   543篇
  2023年   5094篇
  2022年   1282篇
  2021年   3208篇
  2020年   5523篇
  2019年   2347篇
  2018年   7246篇
  2017年   7604篇
  2016年   8181篇
  2015年   8335篇
  2014年   10893篇
  2013年   12594篇
  2012年   4641篇
  2011年   4437篇
  2010年   7258篇
  2009年   9419篇
  2008年   4102篇
  2007年   3030篇
  2006年   4214篇
  2005年   2665篇
  2004年   1933篇
  2003年   1586篇
  2002年   1457篇
  2001年   1953篇
  2000年   1271篇
  1999年   1774篇
  1998年   2138篇
  1997年   1959篇
  1996年   1999篇
  1995年   1720篇
  1994年   1127篇
  1993年   962篇
  1992年   874篇
  1991年   735篇
  1990年   611篇
  1989年   625篇
  1988年   605篇
  1987年   458篇
  1986年   422篇
  1985年   363篇
  1984年   338篇
  1983年   349篇
  1982年   274篇
  1981年   244篇
  1980年   169篇
  1979年   123篇
  1978年   159篇
  1977年   170篇
  1976年   132篇
  1974年   115篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
The environmental context of patient safety and medical errors was explored with specific interest in rural settings. Special attention was paid to unique features of rural: healthcare organizations and their environment that relate to the patient safety issue and medical errors (including the distribution of patients, types of adverse events associated with learning, information flows, triage and transfer decisions, and culture of safety). Relevant organizational theories and strategies fo medical error reduction and prevention in rural health care settings were identified. Financial and technical assistance are needed to support the systematic collection of data from rural hospitals and other entities and to enhance relevant patient safety practices for rural America.  相似文献   
993.
The diagnosis of idiopathic Parkinson's disease (PD) can be achieved with high degrees of accuracy in cases with full expression of classical clinical features. However, diagnostic uncertainty remains in early disease with subtle or ambiguous signs. Functional imaging has been suggested to increase the diagnostic yield in parkinsonian syndromes with uncertain clinical classification. Loss of striatal dopamine nerve terminal function, a hallmark of neurodegenerative Parkinsonism, is strongly related to decreases of dopamine transporter (DAT) density, which can be measured by single photon emission computed tomography (SPECT). The use of DAT‐SPECT facilitates the differential diagnosis in patients with isolated tremor symptoms not fulfilling PD or essential tremor criteria, drug‐induced, psychogenic and vascular Parkinsonism as well as dementia when associated with Parkinsonism. This review addresses the value of DAT‐SPECT in early differential diagnosis, and its potential as a screening tool for subjects at risk of developing PD as well as issues around the assessment of disease progression. © 2007 Movement Disorder Society  相似文献   
994.
In Vitro Wear of Nano-Composite Denture Teeth   总被引:2,自引:0,他引:2  
PURPOSE: Few laboratory tests have been able to substantiate and quantify the wear resistances of polymeric denture teeth. This study evaluated the relative wear resistance of several types of denture teeth using an in vitro wear testing device. MATERIAL AND METHODS: Four different types of denture teeth [nano-filled (Veracia) and micro-filled composites (SR-Orthosit, Endura, Duradent, Surpass), cross-linked acrylic (SR-Postaris, Genios-P, Creapearl, Vitapan Physiodens, Premium 8, Integral), and a conventional acrylic (Biotone)] were used. The flattened buccal surface of each denture tooth was subjected to the evaluation of Knoop hardness (n=5) and localized wear for 100,000 cycles (n=10). Wear values were determined in micrometers using a profilometer. The data for the hardness, wear depth, and worn surface areas were individually analyzed by one-way ANOVA. RESULTS: Knoop hardness values (KHN) ranged from 28.2 to 29.8 for micro-filled composite, 18.9 to 21.6 for cross-linked acrylic, 22.7 for nano-composite, and 18.6 for conventional acrylic teeth. All micro-filled composite teeth were significantly harder than other teeth (p <0.0001). The wear depth values were 90.5 microm for the nano-composite, 69.8 to 93.0 microm for the micro-filled composite, 80.8 to 104.0 microm for the cross-linked acrylic, and 162.5 microm for conventional acrylic teeth. The worn surface areas were 5.1 mm2 for the nano-composite, 2.6 to 3.6 mm2 for the micro-filled composite, 4.4 to 5.7 mm2 for the cross-linked acrylic, and 10.1 mm2 for conventional acrylic teeth. The wear values of the acrylic control were significantly different from all other denture teeth (p <0.001). CONCLUSION: The nano-composite tooth was harder and more wear resistant than the acrylic teeth but not significantly different from most of the cross-linked and micro-filled composite teeth tested.  相似文献   
995.
Certain drugs or chemicals may be added to local anesthetic solutions to enhance the tissue spread of the local anesthetic. Perhaps the best known is glucose (dextrose) added to spinal anesthesia solution to make it hyperbaric and to allow the local anesthetic to spread in the cerebrospinal fluid by gravity, as needed. Hyaluronidase addition has been abandoned in almost all other regional anesthetic blocks except ophthalmologic blocks. Hylauronidase is expensive and it is not devoid of side-effects and, therefore, as low concentrations as possible are recommended. Even as low concentration as 3.75 IU/mL of hyaluronidase is able to enhance the spread of the concentrated local anesthetic solution, causing analgesia and akinesia without damage to the eye muscles. Hyaluronidase addition to local anesthetic solutions is used to some extent also in dermatological surgery. The spread of local anesthetics for topical skin analgesia and anesthesia is promoted by influencing the penetrating property physically (eutectic mixture), electrically (iontophoresis), and encapsulating in liposomes. The penetration (spread) of the local anesthetic through the skin is significantly faster with iontophoresis and liposomes in comparison with the eutectic mixture of local anesthetics.  相似文献   
996.
997.
998.
OBJECTIVE: In 1991, a randomized study was published and demonstrated that use of nonsurgical therapy (chemoradiation) provided similar survival to total laryngectomy (the gold standard) for patients with advanced-stage laryngeal cancer. The purpose of this study was to assess how treatment of advanced laryngeal cancer was influenced by such developments in non-surgical therapy. STUDY DESIGN: Patterns of care study using National Cancer Database (1985-2001). RESULTS: The percentage of advanced-stage patients treated with chemoradiation increased from 8.3% to 20.8% while the proportion treated with radiation alone decreased from 38.9% to 23.0%. Use of chemoradiation increased at a significantly faster rate after the 1991 publication at both community cancer centers and teaching research facilities. The use of total laryngectomy decreased slightly during this period. CONCLUSIONS: The use of chemoradiation increased after the 1991 publication. It was impossible to determine from the NCDB whether additional patients who could benefit from chemo-RT were not offered or did not complete this treatment option. We recommend that treatment recommendations discussed at tumor boards be recorded in cancer registries.  相似文献   
999.
1000.
OBJECTIVE: To determine clinical utility of fine needle aspiration (FNA) in parotid neoplasia. STUDY DESIGN AND SETTING: Retrospective cohort study. METHODS: FNA and final pathology data were reviewed for patients who underwent parotidectomy for malignancy. Surgical outcomes were compared between patients with malignant cytology versus nonmalignant/nondiagnostic cytology. RESULTS: Twenty-seven of 33 primary malignant parotid lesions underwent FNA. Seventeen (63.0%) patients were diagnosed with cancer on FNA. The remaining 16 patients did not undergo FNA (n = 6), had a nondiagnostic FNA specimen (n = 5), or were incorrectly diagnosed with a benign lesion (n = 5). Patients who went on to parotidectomy with intent to treat malignancy based on FNA had significantly higher rates of upfront neck dissections (47.1% vs 12.5%, P = 0.036) as well as clear pathological margins (70.6% vs 31.3%, P = 0.027) vs those with nonmalignant FNA diagnoses. CONCLUSIONS: Preoperative FNA diagnosis of malignancy improves surgical treatment of parotid cancer. SIGNIFICANCE: FNA in the evaluation of parotid masses should strongly be considered.  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