全文获取类型
收费全文 | 38760篇 |
免费 | 6976篇 |
国内免费 | 98篇 |
专业分类
耳鼻咽喉 | 807篇 |
儿科学 | 1220篇 |
妇产科学 | 1019篇 |
基础医学 | 2962篇 |
口腔科学 | 1628篇 |
临床医学 | 5883篇 |
内科学 | 10286篇 |
皮肤病学 | 679篇 |
神经病学 | 2739篇 |
特种医学 | 979篇 |
外科学 | 5371篇 |
综合类 | 339篇 |
现状与发展 | 2篇 |
一般理论 | 20篇 |
预防医学 | 5357篇 |
眼科学 | 689篇 |
药学 | 1922篇 |
中国医学 | 19篇 |
肿瘤学 | 3913篇 |
出版年
2024年 | 165篇 |
2023年 | 1144篇 |
2022年 | 530篇 |
2021年 | 1125篇 |
2020年 | 1440篇 |
2019年 | 877篇 |
2018年 | 1650篇 |
2017年 | 1545篇 |
2016年 | 1795篇 |
2015年 | 1835篇 |
2014年 | 2660篇 |
2013年 | 3095篇 |
2012年 | 2219篇 |
2011年 | 2090篇 |
2010年 | 1946篇 |
2009年 | 2278篇 |
2008年 | 2032篇 |
2007年 | 1835篇 |
2006年 | 2166篇 |
2005年 | 1768篇 |
2004年 | 1612篇 |
2003年 | 1362篇 |
2002年 | 1268篇 |
2001年 | 557篇 |
2000年 | 505篇 |
1999年 | 528篇 |
1998年 | 579篇 |
1997年 | 441篇 |
1996年 | 397篇 |
1995年 | 347篇 |
1994年 | 299篇 |
1993年 | 244篇 |
1992年 | 272篇 |
1991年 | 253篇 |
1990年 | 261篇 |
1989年 | 223篇 |
1988年 | 225篇 |
1987年 | 192篇 |
1986年 | 173篇 |
1985年 | 172篇 |
1984年 | 165篇 |
1983年 | 153篇 |
1982年 | 119篇 |
1981年 | 115篇 |
1980年 | 103篇 |
1979年 | 105篇 |
1978年 | 98篇 |
1977年 | 86篇 |
1975年 | 80篇 |
1973年 | 84篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
J. Lee Jenkins MD MSc Robert E. O'Connor MD MPH David C. Cone MD 《Academic emergency medicine》2006,13(11):1169-1172
This breakout session at the Academic Emergency Medicine 2006 Consensus Conference examined how baseline overcrowding impedes the ability of emergency departments to respond to sudden, unexpected surges in demand for patient care. Differences between daily and catastrophic surge were discussed, and the need to invoke a hospital-wide response to surge was explored. 相似文献
52.
Robert A. Schwartz MD MPH Mordechai M. Tarlow MD W. Clark Lambert MD Ph D 《Dermatologic surgery》2004,30(S2):349-350
Acrochordons (skin tags) are often considered clinically insignificant cutaneous redundancies that should be removed and destroyed with no histopathologic analysis performed. One rarely finds another neoplasm within an acrochordon. We describe a patient with an acrochordon that contained a squamous cell carcinoma that had features resembling a keratoacanthoma. This is the first time to our knowledge that an invasive squamous cell carcinoma has been described within an acrochordon. 相似文献
53.
Objectives: To validate the accuracy of using probabilistic linkage for matching de‐identified ambulance records to a state trauma registry. Methods: This was a retrospective cohort analysis. Three thousand nine hundred nineteen true matches between ambulance and state trauma registry data from 1998 to 2003 were identified by deterministic matching on trauma identification number and verified by human review. Two thousand thirty‐eight ambulance records from trauma patients not meeting criteria for a true match, and an identical number of trauma registry records randomly selected from the one local county served by a different EMS provider, were included as nonmatches. There were 17 variables considered for linkage, which included the following: age, gender, race, county, hospital, date, rural setting, call and arrival times, mechanism, penetrating injury, vital signs, intubation, and intoxication. Probabilistic linkage was used to link the two data sets, using seven different combinations of common variables (maximum, 17; minimum, 4). The sensitivity and specificity of identifying true matches and nonmatches (95% confidence intervals [95% CI]) were calculated for each combination of variables. Results: Using all 17 available variables, 3,766 of 3,919 true matches were appropriately linked (sensitivity, 96.1%; 95% CI = 95.4% to 96.7%), with eight mismatches (specificity, 99.6%; 95% CI = 99.2% to 99.8%). Sensitivity fell below 95% with < 15 variables; however, sensitivity was very dependent on the inclusion of variables with high discriminatory power. Specificity remained >98% regardless of the number of variables included. Conclusions: Probabilistic linkage is a valid method for matching ambulance records to a trauma registry without the use of patient identifiers; however, the sensitivity of identifying true matches is critically dependent on the number and type of common variables included in the analysis. 相似文献
54.
55.
56.
57.
D. Le Elizabeth Eric R. Powers Jian-Ping Bin Howard Leong-Poi N. Craig Goodman Sanjiv Kaul 《Journal of nuclear cardiology》2007,14(2):207-214
Background The mechanism by which transmyocardial revascularization (TMR) offers clinical benefit is controversial. We hypothesized that
TMR ameliorates ischemia by reversing paradoxical catecholamine-induced vasoconstriction.
Methods and Results Chronic ischemic cardiomyopathy was created in 11 dogs by placing ameroid constrictors on the proximal coronary arteries and
their major branches. Six weeks later, 35 channels were created percutaneously in the left circumflex artery region, with
the left anterior descending artery region serving as control. At rest, wall thickening and myocardial blood flow did not
change in the treated region, whereas they deteriorated in the control bed. Contractile and myocardial blood flow reserve
increased in the treated region but deteriorated in the control region. There was diminished iodine 123 metaiodobenzylguanidine
uptake and a significant reduction in noradrenergic nerves in the treated region compared with the control region, with a
corresponding reduction in tissue tyrosine hydroxylase activity.
Conclusions We conclude that the absence of a catecholamine-induced reduction in MBF reserve and contractile reserve in the TMR-treated
region with associated evidence of neuronal injury indicates that the relief of exercise-induced ischemia after TMR most likely
results from reversal of paradoxical catecholamine-induced vasoconstriction. These findings may have implications in selecting
patients who would benefit from TMR.
Supported in part by grants from the National Institutes of Health (R01-HL66034 and K-08-HL074290-01). Bethesda. Md. The radio-labeled
microspheres were provided by DuPont Pharmaceuticals, North Billerica. Mass, and the ultrasound equipment was supplied by
Philips. Andover, Mass. Dr Leong-Poi was the recipient of a Fellowship Training Grant from the Canadian Institute of Health
Research and the Heart and Stroke Foundation of Canada. 相似文献
58.
59.
60.
Optimal timing of a single dose of zoledronic acid to increase strength in rat fracture repair. 总被引:4,自引:0,他引:4
Negin Amanat Michelle McDonald Craig Godfrey Lynne Bilston David Little 《Journal of bone and mineral research》2007,22(6):867-876
We hypothesized that ZA treatment would bolster fracture repair. In a rat model for closed fracture healing, a single dose of ZA at 0, 1, or 2 wk after fracture significantly increased BMC and strength of the healed fracture. Delaying the dose (1 or 2 wk after fracture) displayed superior results compared with dosing at the time of fracture. INTRODUCTION: Bisphosphonates are known to increase bone strength and thus the resistance to fracture by decreasing osteoclastic bone resorption. These properties may enable bisphosphonates to also increase the strength of fracture repair. Zoledronic acid (ZA) is a potent bisphosphonate with a high affinity for bone mineral, allowing bolus intravenous dosing in a range of indications. In this study, we examined the application of bolus dose ZA in endochondral fracture repair. MATERIALS AND METHODS: Carbon-14 labeled ZA was used in a closed rat fracture model. Rats were divided into five treatment groups (n = 25 per group): saline control, local ZA (0.01 mg/kg), and three systemic bolus ZA groups (0.1 mg/kg) with different administration times: at fracture, 1 wk after fracture, and 2 wk after fracture. Rats were killed 6 wk postoperatively. Postmortem analyses included radiography, QCT, microCT, biomechanical testing, scintillation counting, autoradiography, and histology. RESULTS: Single-dose systemic ZA administration significantly increased callus volume, callus BMC, and mechanical strength. Perioperative treatment increased mechanical strength by 30% compared with controls (p < 0.05). Administering the systemic dose at 1 or 2 wk after fracture further increased mechanical strength compared with controls by 44% and 50%, respectively (p < 0.05). No significant differences in mechanical parameters were seen with local injection at the dose studied. Autoradiographic analysis indicated that ZA binds significantly to bone that is present at the time of administration. ZA quantification indicated that delayed administration significantly increased the uptake efficiency in the callus. Histological and microCT analysis showed that ZA treated calluses had a distinctive internal structure consisting of an intricate network of retained trabecular bone. CONCLUSIONS: The timing of a single systemic dose of ZA plays an important role in the modulation of callus properties in this rat fracture model; delaying the single dose produces a larger and stronger callus. 相似文献