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   707篇
  免费   30篇
  国内免费   3篇
耳鼻咽喉   4篇
儿科学   13篇
妇产科学   12篇
基础医学   71篇
口腔科学   35篇
临床医学   50篇
内科学   169篇
神经病学   40篇
特种医学   22篇
外科学   216篇
综合类   5篇
预防医学   16篇
眼科学   2篇
药学   28篇
中国医学   2篇
肿瘤学   55篇
  2023年   4篇
  2022年   8篇
  2021年   13篇
  2020年   5篇
  2019年   11篇
  2018年   17篇
  2017年   10篇
  2016年   8篇
  2015年   9篇
  2014年   13篇
  2013年   22篇
  2012年   26篇
  2011年   45篇
  2010年   29篇
  2009年   27篇
  2008年   45篇
  2007年   56篇
  2006年   37篇
  2005年   51篇
  2004年   33篇
  2003年   31篇
  2002年   29篇
  2001年   31篇
  2000年   30篇
  1999年   14篇
  1998年   6篇
  1997年   13篇
  1996年   5篇
  1995年   8篇
  1994年   2篇
  1993年   4篇
  1992年   7篇
  1991年   9篇
  1990年   5篇
  1989年   13篇
  1988年   5篇
  1987年   13篇
  1986年   16篇
  1985年   4篇
  1984年   4篇
  1983年   1篇
  1982年   4篇
  1981年   4篇
  1980年   1篇
  1979年   2篇
  1973年   2篇
  1971年   3篇
  1969年   2篇
  1968年   2篇
  1908年   1篇
排序方式: 共有740条查询结果,搜索用时 328 毫秒
11.
12.
We have shown that fullerene (C60) becomes soluble in water by mixing fullerene and amyloid β peptide (Aβ40) whose fibril structures are considered to be associated with Alzheimer''s disease. The water-solubility of fullerene arises from the generation of a nanosized complex between fullerene and the monomer species of Aβ40 (Aβ40-C60). The prepared Aβ40-C60 exhibits photo-induced activity with visible light to induce the inhibition of Aβ40 fibrillation and the cytotoxicity for cultured HeLa cells. The observed photo-induced phenomena result from the generation of singlet oxygen via photoexcitation, inducing oxidative damage to Aβ40 and HeLa cells. The oxidized Aβ40 following photoexcitation of Aβ40-C60 was confirmed by mass spectrometry.

We have shown that fullerene (C60) becomes soluble in water by mixing fullerene and amyloid β peptide (Aβ40) whose fibril structures are considered to be associated with Alzheimer''s disease.  相似文献   
13.
14.
Despite >50 years of research work since the discovery of sliding filament mechanism in muscle contraction, structural details of the coupling of cyclic cross-bridge movement to ATP hydrolysis are not yet fully understood. An example would be whether lever arm tilting on the myosin filament backbone will occur in the absence of actin. The most direct way to elucidate such movement is to record ATP-induced cross-bridge movement in hydrated thick filaments. Using the hydration chamber, with which biological specimens can be kept in an aqueous environment in an electron microscope, we have succeeded in recording ATP-induced cross-bridge movement in hydrated thick filaments consisting of rabbit skeletal muscle myosin, with gold position markers attached to the cross-bridges. The position of individual cross-bridges did not change appreciably with time in the absence of ATP, indicating stability of time-averaged cross-bridge mean position. On application of ATP, individual cross-bridges moved nearly parallel to the filament long axis. The amplitude of the ATP-induced cross-bridge movement showed a peak at 5–7.5 nm. At both sides of the filament bare region, across which the cross-bridge polarity was reversed, the cross-bridges were found to move away from, but not toward, the bare region. Application of ADP produced no appreciable cross-bridge movement. Because ATP reacts rapidly with the cross-bridges (M) to form complex (M·ADP·Pi) with an average lifetime >10 s, the observed cross-bridge movement is associated with reaction, M + ATP → M·ADP·Pi. The cross-bridges were observed to return to their initial position after exhaustion of ATP. These results constitute direct demonstration of the cross-bridge recovery stroke.  相似文献   
15.
16.
We describe herein a case of unilateral pulmonary agenesis (PA) with oesophageal atresia (EA)/tracheoesophageal fistula (TEF) that was diagnosed prenatally and repaired by esophagoesophagostomy with stable postoperative course. The patient was born at 34 weeks gestation, after ultrasonography at 22 weeks gestation showed possible right-sided diaphragmatic eventration or PA and EA was subsequently suspected due to hydramnios. The initial X-ray showed mediastinal shift to the right, and coil up sign of the nasogastric tube, without intracardiac anomaly. Immediately after the diagnosis of EA/TEF and unilateral PA on day 0, the patient was intubated in the operating room, and a gastrostomy tube was placed. After pulmonary status stabilized, at 4 days old, EA/TEF was repaired through a thoracotomy in the right 4th intercostal space. The right main bronchus was noted to continue into the distal oesophagus; this fistula was ligated and divided, and a single-layer esophagoesophagostomy was performed under mild tension with one vertebral gap. The neonate was maintained on mechanical ventilation and gradually weaned to extubation at 7 days old. The postoperative course was uneventful, with the exception of prolonged jaundice that emerged at 3 months old. Laparoscopic cholangiography at that time excluded biliary atresia, and jaundice resolved spontaneously. The patient has not shown any respiratory symptoms or feeding difficulties as of the 12-month follow-up.  相似文献   
17.
18.
PurposeIt is clinically believed that humans with a broad and rounded dental arch accompanied by a shallow curve of Spee have good masticatory function. However, the relationship between them has not been elucidated fully. The purpose of this study was to quantitatively examine the relationship between occlusal curvatures and bite force.Materials and methodsBite force was measured and analyzed in 20 young adults with healthy permanent dentition and normal stomatognathic function using a bite force recording system. Study models of the mandibular dental arch were scanned with CCD cameras, and X, Y and Z coordinates of the cusp tips of the molars were recorded. Their occlusal curvatures were analyzed using a three-dimensional measurement system.ResultsBite force showed significant positive correlations (0.52 < R < 0.57) with the radius of the anteroposterior occlusal arc of the molar region and the radii of the translateral occlusal arcs in the second premolar, first molar and second molar regions, and showed significant positive correlation (R = 0.71) with the radius of the occlusal sphere of the molar region.ConclusionsIt was suggested that occlusal curvatures is related with the magnitude of bite force, and that the three dimensional spherical analysis of occlusal curvatures is useful predictor of the masticatory function.  相似文献   
19.

Objectives

Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is becoming common in Japan. Oral and maxillofacial radiologists must diagnose BRONJ in general practice. However, little information on how to recognise BRONJ is available. The purpose of this study, therefore, was to confirm the recognition of BRONJ among Japanese oral and maxillofacial radiologists.

Methods

A questionnaire including 14 main queries and relevant branch queries was created and sent to 29 Japanese institutions employing oral and maxillofacial radiologists.

Results

A large number of patients (705) with BRONJ during the last 3 years were reported by 23 institutions (25 responders) that participated in our survey. The rate of osteonecrosis of the jaw associated with intravenous bisphosphonates was almost identical to that associated with oral bisphosphonates. This finding was inconsistent with worldwide data. About half of the responders felt that the diagnosis of BRONJ based on imaging was difficult. No specific modality was selected for identifying the early signs of BRONJ, although 19 responders selected multi-detector computed tomography followed by magnetic resonance imaging as the best modality for determining the extent of BRONJ. Almost all responders felt that the detection of early signs and determination of lesion extent on imaging were important roles of oral and maxillofacial radiologists.

Conclusions

Oral and maxillofacial radiologists recognised their roles in BRONJ diagnosis; however, insufficient evidence regarding the accomplishment of these roles is available. Japanese oral and maxillofacial radiologists must accumulate a large number of BRONJ images, analyse them in cooperation with one another and share the information obtained from their analysis.  相似文献   
20.
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