全文获取类型
收费全文 | 329134篇 |
免费 | 25498篇 |
国内免费 | 1262篇 |
专业分类
耳鼻咽喉 | 3883篇 |
儿科学 | 8853篇 |
妇产科学 | 6328篇 |
基础医学 | 44006篇 |
口腔科学 | 6511篇 |
临床医学 | 34927篇 |
内科学 | 66937篇 |
皮肤病学 | 4596篇 |
神经病学 | 30502篇 |
特种医学 | 11018篇 |
外国民族医学 | 21篇 |
外科学 | 49048篇 |
综合类 | 5063篇 |
一般理论 | 373篇 |
预防医学 | 30312篇 |
眼科学 | 8310篇 |
药学 | 23198篇 |
6篇 | |
中国医学 | 435篇 |
肿瘤学 | 21567篇 |
出版年
2023年 | 1638篇 |
2022年 | 2908篇 |
2021年 | 6437篇 |
2020年 | 3911篇 |
2019年 | 6288篇 |
2018年 | 7205篇 |
2017年 | 5354篇 |
2016年 | 5920篇 |
2015年 | 6930篇 |
2014年 | 10024篇 |
2013年 | 14078篇 |
2012年 | 21111篇 |
2011年 | 22209篇 |
2010年 | 12312篇 |
2009年 | 11130篇 |
2008年 | 19474篇 |
2007年 | 20590篇 |
2006年 | 20330篇 |
2005年 | 20369篇 |
2004年 | 19060篇 |
2003年 | 17740篇 |
2002年 | 16689篇 |
2001年 | 4772篇 |
2000年 | 4394篇 |
1999年 | 4763篇 |
1998年 | 4051篇 |
1997年 | 3371篇 |
1996年 | 2973篇 |
1995年 | 2823篇 |
1994年 | 2506篇 |
1993年 | 2270篇 |
1992年 | 3315篇 |
1991年 | 3142篇 |
1990年 | 2873篇 |
1989年 | 2810篇 |
1988年 | 2708篇 |
1987年 | 2685篇 |
1986年 | 2611篇 |
1985年 | 2608篇 |
1984年 | 2579篇 |
1983年 | 2361篇 |
1982年 | 2177篇 |
1981年 | 1999篇 |
1980年 | 1746篇 |
1979年 | 1901篇 |
1978年 | 1605篇 |
1977年 | 1377篇 |
1976年 | 1288篇 |
1975年 | 1168篇 |
1974年 | 1322篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
A new strategy to yield information from the maximum number of voxels, each at the optimum signal-to-noise ratio (SNR) per unit time, in MR spectroscopic imaging (MRSI) is introduced. In the past, maximum acquisition duty-cycle was obtained by multiplexing in time several single slices each repetition time (TR), while optimal SNR was achieved by encoding the entire volume of interest (VOI) each TR. We show that optimal SNR and acquisition efficiency can both be achieved simultaneously by multiplexing in space and time several slabs of several slices, each. Since coverage of common VOIs in 3D proton MRSI in the human brain typically requires eight or more slices, at 3 T or higher magnetic fields, two or more slabs can fit into the optimum TR (approximately 1.6 s). Since typically four or less slices would then fit into each slab, Hadamard encoding is favored in that direction for slice profile reasons. It is demonstrated that per fixed examination length, the new method gives, at 3 T, twice as many voxels, each of the same SNR and size, compared with current 3D chemical shift imaging techniques. It is shown that this gain will increase for more extensive spatial coverage or higher fields. 相似文献
82.
Lisa A. Lang DDS MS David C. Holmes DDS MS Craig Passon DDS MS Robert M. Trombly DDS JD Jeffrey D. Astroth DDS MSPH Arnold F. Tavel DMD 《Journal of prosthodontics》2003,12(3):206-210
Using complete denture treatment as an introduction to clinical patient care for dental students, the purposes of the Complete Denture Prosthodontics Transition Clinic at the University of Colorado School of Dentistry are to reduce the time lapse between the preclinical complete denture prosthodontics course and the first denture patient experience, and to encourage development of student self-confidence and skills. In the 2002 spring semester, faculty at the University of Colorado School of Dentistry initiated the Complete Denture Prosthodontics Transition Clinic for DS-II (second-year) dental students, as an introduction to clinical patient care. Each patient was assigned to a team of two dental students. Three Division of Prosthodontics faculty members staffed each clinic session, providing a student-to-faculty ratio of approximately 6.6:1 and a patient-to-faculty ratio of approximately 3.3:1. All DS-II students in the Class of 2004 delivered their first complete dentures no later than 8 months (average, 184 days) after the last day of the preclinical complete denture prosthodontics course. The time from the diagnostic appointment through the denture placement appointment averaged 39 days for patients treated in this program, compared with an average of 98 days or more for previous classes. The program was successful in achieving the goal of reducing the time lapse between the preclinical complete denture prosthodontics course and the first denture patient experience. 相似文献
83.
Ayad Al Darrab Jerome Fan Christopher M B Fernandes Rosanne Zimmerman Rhonda Smith Andrew Worster Teresa Smith Kelly O'Connor 《European journal of emergency medicine》2006,13(1):32-35
STUDY OBJECTIVES: Use of fast track has been shown to improve the emergency department flow of less urgent patients. It has been speculated, however, that this could negatively affect the care of urgent patients. The objective of this study was to determine whether a dedicated fast track for less urgent patients [Canadian Triage and Acuity scale category 4/5 (CTAS 4/5)] affected (1) the time to assessment for urgent patients (CTAS 3), (2) the length of stay for less urgent patients (CTAS 4 and 5), and (3) the left-without-being-seen rate. METHODS: In June 2003, fast track was opened in our emergency department from 13:00 to 19:00 h. A before-after intervention comparison analysis was completed for 1 week in Aug 2002 and the same week in Aug 2003. Data collected included (1) time to assessment of CTAS 3 patients, (2) the length of stay for CTAS 4/5 patients, and (3) percentage of patients who left without being seen. RESULTS: A total of 368 patients were reviewed for 2002 and 380 patients were reviewed for 2003. Median time to assessment of CTAS 3 patients presenting from 13:00 to 19:00 h was reduced from 66 min (Interquartile range: 40, 94 min) in 2002 to 60 min (IQR: 38, 108 min) after fast track was open in 2003 (P = 0.95). Median length of stay of CTAS 4 and 5 patients was reduced from 170 min (IQR: 111, 256 min) to 110 min (IQR: 69, 185 min) (P < 0.001). The overall left-without-being-seen rate decreased from 5% (20/368) to 2% (9/380). CONCLUSION: A dedicated fast track for CTAS 4/5 patients can reduce the length of stay and the left-without-being-seen rate with no impact on CTAS 3 patients seen in the main emergency department. 相似文献
84.
David M Dohan Joseph Choukroun Antoine Diss Steve L Dohan Anthony J J Dohan Jaafar Mouhyi Bruno Gogly 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2006,101(3):e37-e44
Platelet-rich fibrin (PRF) belongs to a new generation of platelet concentrates geared to simplified preparation without biochemical blood handling. In this initial article, we describe the conceptual and technical evolution from fibrin glues to platelet concentrates. This retrospective analysis is necessary for the understanding of fibrin technologies and the evaluation of the biochemical properties of 3 generations of surgical additives, respectively fibrin adhesives, concentrated platelet-rich plasma (cPRP) and PRF. Indeed, the 3-dimensional fibrin architecture is deeply dependent on artificial clinical polymerization processes, such as massive bovine thrombin addition. Currently, the slow polymerization during PRF preparation seems to generate a fibrin network very similar to the natural one. Such a network leads to a more efficient cell migration and proliferation and thus cicatrization. 相似文献
85.
Allison J. Cowin PhD ; Nicholas Hatzirodos BSc ; Justin Rigden PhD ; Robert Fitridge FRACS ; David A. Belford PhD 《Wound repair and regeneration》2006,14(4):421-426
High levels of tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine, are present in the wound fluid of chronic nonhealing wounds. This leads to increased inflammation, cytokine expression, and ultimately results in impaired wound healing and tissue destruction. Etanercept is a recombinant fusion protein that consists of the soluble TNF receptor (p75) linked to the Fc portion of human IgG1. It is an effective inhibitor of TNF-alpha and has been shown to provide rapid and sustained improvement in rheumatoid arthritis by acting as a soluble receptor binding TNF-alpha and preventing its proinflammatory activities. Therefore, the aim of this study was to determine whether Etanercept could inhibit TNF-alpha activity in chronic wound fluid. Wound fluid was collected from the venous leg ulcers of 16 different patients. The effect of Etanercept on TNF-alpha activity was evaluated using both a TNF-alpha bioassay and an enzyme-linked immunoassay. Etanercept was found to reduce the cytotoxic effect of chronic wound fluid on L929 fibroblasts by approximately 30% and neutralized TNF-alpha binding in the enzyme-linked immunoassay by up to 80%. Direct application of Etanercept to chronic wounds may therefore reduce the inflammatory activity of TNF-alpha, which could reduce the chronicity of venous leg ulcers and thus aid in the healing of these wounds. 相似文献
86.
Background
Both diabetes and obesity syndromes are recognized to promote lumbar vertebral instability, premature osteodegeneration, exacerbate progressive osteoporosis and increase the propensity towards vertebral degeneration, instability and deformation in humans. 相似文献87.
Avninder Dhaliwal Adrienne L West Jonathan D Trobe David C Musch 《Journal of neuro-ophthalmology》2006,26(1):4-10
BACKGROUND: The relationship between the circumstances and severity of closed head injury (CHI) and the clinical and imaging features of cranial nerve 3, 4, and 6 palsies has not been rigorously addressed in a large study. METHODS: Retrospective chart review of 210 consecutive patients with CHI examined at a single tertiary care center from 1987 to 2002. Patients were located by searching the ophthalmology inpatient consultation and neuro-ophthalmology outpatient databases and hospital emergency room billing codes for a diagnosis of traumatic 3, 4, or 6 cranial nerve palsy (Cranial Nerve Injury Group) and a diagnosis of CHI without traumatic 3, 4, or 6 nerve palsy (Control Group). The Cranial Nerve Injury Group was then subdivided into two groups: those with injuries to an individual cranial nerve and those with multiple (including bilateral) cranial nerve injuries. Comparisons between groups were based on age, gender, type of accident, Glasgow Coma Scale (GCS), documented loss of consciousness (LOC), type of ocular injury, presence of systemic injury, need for rehabilitation, physical therapy and cognitive scores, and imaging features. RESULTS: The Cranial Nerve Injury Group had a significantly higher severity of head injury, more CT abnormalities, and worse short-term neurologic outcomes as compared with the Control Group. These trends were also found when each cranial nerve injury subgroup was compared with the Control Group. Those with cranial nerve 3 palsy had the most severe head injury; those with cranial nerve 4 palsy had an intermediate level of head injury; and those with cranial nerve 6 palsy had the lowest level of head injury. There were no consistent associations between the location of the imaging abnormalities and which cranial nerve was damaged. CONCLUSIONS: CHI with palsy of an ocular motor nerve was more severe than CHI without ocular motor nerve palsy, as measured by the GCS, intracranial and skull imaging abnormalities, and a greater frequency of inpatient rehabilitation. Palsy of cranial nerve 3 was associated with relatively more severe CHI than was palsy of cranial nerves 4 or 6. The location of the imaging abnormalities did not correlate with a particular cranial nerve injury. 相似文献
88.
Mark S. Wallace Steven G. Charapata Robert Fisher Michael Byas‐Smith Peter S. Staats Martha Mayo Dawn McGuire David Ellis 《Neuromodulation》2006,9(2):75-86
Objective. The safety and efficacy of intrathecal (IT) ziconotide was studied in a randomized, double‐blind, placebo‐controlled trial. Materials and Methods. Patients (169 ziconotide, 86 placebo) with severe chronic nonmalignant pain unresponsive to conventional therapy and a visual analog scale of pain intensity (VASPI score) ≥ 50 mm were treated over a 6‐day period in an inpatient hospital setting. Initial starting dose was 0.4 µg/hour and was titrated to analgesia or intolerance (maximum dose 7.0 µg/hour). The starting and maximum doses were reduced to 0.1 µg/hour and 2.4 µg/hour, respectively, due to adverse events (AEs). Results. The mean percent reduction in VASPI score from baseline was 31.2% and 6.0% for ziconotide‐ and placebo‐treated patients, respectively (p ≤ 0.001). During the initial titration phase, a significantly greater percentage of patients in the ziconotide group compared to the placebo group reported AEs, including abnormal gait, amblyopia, dizziness, nausea, nystagmus, pain, urinary retention, and vomiting. Conclusion. Ziconotide provided significant analgesia in patients for whom conventional therapy failed. However, there was a considerable incidence of ziconotide‐associated AEs due to the rapid titration and high doses administered. 相似文献
89.
90.