全文获取类型
收费全文 | 8912篇 |
免费 | 525篇 |
国内免费 | 43篇 |
专业分类
耳鼻咽喉 | 114篇 |
儿科学 | 236篇 |
妇产科学 | 166篇 |
基础医学 | 1470篇 |
口腔科学 | 275篇 |
临床医学 | 848篇 |
内科学 | 1285篇 |
皮肤病学 | 497篇 |
神经病学 | 1055篇 |
特种医学 | 399篇 |
外科学 | 1331篇 |
综合类 | 102篇 |
一般理论 | 6篇 |
预防医学 | 537篇 |
眼科学 | 199篇 |
药学 | 429篇 |
中国医学 | 1篇 |
肿瘤学 | 530篇 |
出版年
2023年 | 67篇 |
2022年 | 119篇 |
2021年 | 237篇 |
2020年 | 138篇 |
2019年 | 183篇 |
2018年 | 216篇 |
2017年 | 151篇 |
2016年 | 188篇 |
2015年 | 190篇 |
2014年 | 292篇 |
2013年 | 353篇 |
2012年 | 508篇 |
2011年 | 465篇 |
2010年 | 277篇 |
2009年 | 212篇 |
2008年 | 393篇 |
2007年 | 416篇 |
2006年 | 353篇 |
2005年 | 380篇 |
2004年 | 365篇 |
2003年 | 358篇 |
2002年 | 339篇 |
2001年 | 57篇 |
1999年 | 71篇 |
1998年 | 92篇 |
1997年 | 70篇 |
1996年 | 67篇 |
1995年 | 46篇 |
1994年 | 45篇 |
1993年 | 56篇 |
1992年 | 49篇 |
1988年 | 44篇 |
1985年 | 52篇 |
1982年 | 57篇 |
1980年 | 58篇 |
1933年 | 50篇 |
1932年 | 44篇 |
1931年 | 50篇 |
1930年 | 60篇 |
1928年 | 43篇 |
1927年 | 44篇 |
1926年 | 54篇 |
1924年 | 41篇 |
1923年 | 54篇 |
1922年 | 54篇 |
1921年 | 51篇 |
1914年 | 51篇 |
1913年 | 79篇 |
1912年 | 48篇 |
1911年 | 50篇 |
排序方式: 共有9480条查询结果,搜索用时 0 毫秒
1.
Peter Marhofer Malachy Columb Phil M. Hopkins Manfred Greher Daniela Marhofer Max R. Levi Bienzle Markus Zeitlinger 《British journal of anaesthesia》2019,122(4):525-531
Background
The efficacy of dexamethasone in extending the duration of local anaesthetic block is uncertain. In a randomised controlled triple blind crossover study in volunteers, we tested the hypothesis that neither i.v. nor perineurally administered dexamethasone prolongs the sensory block achieved with ropivacaine.Methods
Ultrasound-guided ulnar nerve blocks (ropivacaine 0.75% wt/vol, 3 ml, with saline 1 ml with or without dexamethasone 4 mg) were performed on three occasions in 24 male volunteers along with an i.v. injection of saline 1 ml with or without dexamethasone 4 mg. The combinations of saline and dexamethasone were as follows: control group, perineural and i.v. saline; perineural group, perineural dexamethasone and i.v. saline; i.v. group, perineural saline and i.v. dexamethasone. Sensory block was measured using a VAS in response to pinprick testing. The duration of sensory block was the primary outcome and time to onset of sensory block the secondary outcome.Results
All 24 subjects completed the trial. The median [inter-quartile range (IQR)] duration of sensory block was 6.87 (5.85–7.62) h in the control group, 7.37 (5.78–7.93) h in the perineural group and 7.37 (6.10–7.97) h in the i.v. group (P=0.61). There was also no significant difference in block onset time between the three groups.Conclusion
Dexamethasone 4 mg has no clinically relevant effect on the duration of sensory block provided by ropivacaine applied to the ulnar nerve.Clinical trial registration
DRKS, 00014604; EudraCT, 2018-001221-98. 相似文献2.
3.
Robert A. Mischkowski Max J. Zinser Alexander C. Kübler Barbara Krug Ulrich Seifert Joachim E. Zller 《Journal of cranio-maxillo-facial surgery》2006,34(8):478-483
BACKGROUND: An augmented reality tool for computer assisted surgery named X-Scope allows visual tracking of real anatomical structures in superposition with volume rendered CT or MRI scans and thus can be used for navigated translocation of bony segments. METHODS: In a feasibility study X-Scope was used in orthognathic surgery to control the translocation of the maxilla after Le Fort I osteotomy within a bimaxillary procedure. The situation achieved was compared with the pre-operative situation by means of cephalometric analysis on lateral and frontal cephalograms. RESULTS: The technique was successfully utilized in 5 patients. Maxillary positioning using X-Scope was accomplished accurately within a range of 1mm. The tool was used in all cases in addition to the usual intra-operative splints. A stand-alone application without conventional control does not yet seem reasonable. CONCLUSION: Augmented reality tools like X-Scope may be helpful for controlling maxillary translocation in orthognathic surgery. The application to other interventions in cranio-maxillofacial surgery such as Le Fort III osteotomy, fronto-orbital advancement, and cranial vault reshaping or repair may also be considered. 相似文献
4.
A patient with long-standing Tourette's syndrome had a dramatic exacerbation of symptoms following the rapid withdrawal of haloperidol. Clonidine administration resulted in a disappearance of tics, which recurred 6 days later. The role of clonidine in blocking withdrawal-induced symptoms in patients with Tourette's syndrome treated with long-term neuroleptics is discussed from a clinical and neurobiological perspective. The implications of this case for the treatment of supersensitivity psychosis and tricyclic withdrawal states with clonidine are also discussed. 相似文献
5.
6.
Catherine Guette Christian Legros Guewen Tournois Max Goyffon Marie-Louise Célérier 《Toxicon》2006,47(6):640-649
In order to establish a venom fingerprint and a peptide profile of the Lasiodora parahybana tarantula venom gland, we used conventional methods such as reversed phase liquid chromatography coupled to an electrospray-ionisation hybrid quadrupole time of flight mass spectrometer (LC/ESI-QqTOFMS), matrix-assisted laser desorption/ionization time-of-flight-MS (MALDI-TOFMS) and direct study of L. parahybana venom by nanospray-ionization QqTOFMS (nanoESI-QqTOFMS) and a new technology for the direct analysis of fresh tissues using MALDI-TOFMS. The analysis of the crude venom allowed the characterization of specific juvenile and adult biomarkers. In situ MALDI analysis of L. parahybana venom gland sections revealed different peptide expression levels all along the gland and non-processed peptide precursors, demonstrating the power of the method for the dynamic investigation of peptide evolution in the venom gland of spiders. 相似文献
7.
James M Stringham Billy R Hammond Billy R Wooten D Max Snodderly 《Optometry and vision science》2006,83(12):887-894
PURPOSE: Macular pigment (MP) filters short-wavelength light before it reaches the visual pigments. At peak absorbance (460 nm), transmission of light through MP can range from almost 100% transmission to as little as 3%. As a result of the uneven topographic distribution of MP, spatial nonuniformities in visual perception would result if the visual system did not compensate for filtering differences across the central retina. This study characterizes compensation for different densities of MP. METHODS: Sixteen young subjects (aged 24-40 years) with a wide range of MP density were studied. Increment thresholds were measured at 440 and 500 nm in the center of the fovea and at 6 degrees to 7 degrees eccentricity using conditions chosen to isolate the pi-1 mechanism. For six of the subjects, increment thresholds were also obtained for eccentricities of 1 degrees , 1.75 degrees , and 3 degrees . MP density was measured using heterochromatic flicker photometry at the same locations as the increment thresholds. RESULTS: Peak sensitivity of the short-wavelength pathway across the central retina was constant despite MP density differences as large as 1.0 log unit. CONCLUSIONS: These results suggest that the visual system increases gain of the S-cone pathway to offset light absorption by MP. 相似文献
8.
Max Heiland Philipp Pohlenz Marco Blessmann Christian R Habermann Lars Oesterhelweg Philipp C Begemann Christian Schmidgunst Felix A S Blake Klaus Püschel Rainer Schmelzle Dirk Schulze 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2007,104(6):814-820
OBJECTIVE: The aim of this study was to evaluate soft tissue image quality of a mobile cone-beam computed tomography (CBCT) scanner with an integrated flat-panel detector. STUDY DESIGN: Eight fresh human cadavers were used in this study. For evaluation of soft tissue visualization, CBCT data sets and corresponding computed tomography (CT) and magnetic resonance imaging (MRI) data sets were acquired. Evaluation was performed with the help of 10 defined cervical anatomical structures. RESULTS: The statistical analysis of the scoring results of 3 examiners revealed the CBCT images to be of inferior quality regarding the visualization of most of the predefined structures. Visualization without a significant difference was found regarding the demarcation of the vertebral bodies and the pyramidal cartilages, the arteriosclerosis of the carotids (compared with CT), and the laryngeal skeleton (compared with MRI). Regarding arteriosclerosis of the carotids compared with MRI, CBCT proved to be superior. CONCLUSIONS: The integration of a flat-panel detector improves soft tissue visualization using a mobile CBCT scanner. 相似文献
9.
Philipp Pohlenz Marco Blessmann Felix Blake Sven Heinrich Rainer Schmelzle Max Heiland 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2007,103(3):412-417
OBJECTIVES: Intraoperative cone-beam computerized tomography (CBCT) imaging has been introduced in oral and maxillofacial surgery. Using midfacial fractures as the pioneer model, this study describes the spectrum of further promising clinical indications for intraoperative CBCT and a clinical combination with intraoperative navigation. STUDY DESIGN: One hundred seventy-nine patients admitted for surgical treatment of the facial skeleton were included in the study. Intraoperatively, 3-dimensional images were generated with the mobile CBCT scanner Arcadis Orbic 3D, obtained from Siemens Medical Solutions, in a variety of indications. RESULTS: The acquisition of the data sets was uncomplicated, and image quality was sufficient to assess the postoperative result in all cases. In the example of a facial gunshot injury, a navigation system for intraoperative localization of the metal foreign bodies was used. 相似文献
10.
OBJECTIVE AND IMPORTANCE: Fusiform aneurysms of the vertebrobasilar arteries that progressively enlarge causing symptomatic brainstem compression are dangerous and their treatment is difficult. A patient with such an aneurysm treated successfully with staged, microsurgical occlusions of the proximal vertebral arteries is described, and the literature pertaining to this rare condition is briefly reviewed. CLINICAL PRESENTATION: A 48-year-old man with a fusiform basilar trunk aneurysm of uncertain etiology presented initially with transient ischemic attacks (TIAs) of the posterior circulation that ceased with anticoagulation. Four years later he presented again with progressive ataxia, dysphagia and dysphonia due to considerable enlargement of the aneurysm causing brainstem compression. INTERVENTION: Staged microsurgical vertebral artery occlusions proximal to the aneurysm were performed. The second (left) vertebral artery was clipped only after the patient passed its temporary occlusion with an endovascular test balloon. The aneurysm subsequently thrombosed, the distal basilar artery kept patent by a single (left) posterior communicating artery. The patient's clinical condition improved markedly over a number of months as the aneurysm mass atrophied. CONCLUSION: Giant vertebrobasilar aneurysms are rare but treacherous lesions, sometimes justifying aggressive management. Carefully selected patients with progressive and severe symptoms due to brainstem compression may tolerate proximal vertebral artery occlusions, provided there is adequate collateral flow to the basilar termination and all of its perforating branches. 相似文献