全文获取类型
收费全文 | 104125篇 |
免费 | 7942篇 |
国内免费 | 378篇 |
专业分类
耳鼻咽喉 | 1139篇 |
儿科学 | 2603篇 |
妇产科学 | 1687篇 |
基础医学 | 14839篇 |
口腔科学 | 2235篇 |
临床医学 | 10628篇 |
内科学 | 22095篇 |
皮肤病学 | 1848篇 |
神经病学 | 11078篇 |
特种医学 | 4267篇 |
外国民族医学 | 6篇 |
外科学 | 14883篇 |
综合类 | 1274篇 |
一般理论 | 73篇 |
预防医学 | 8071篇 |
眼科学 | 1740篇 |
药学 | 7028篇 |
中国医学 | 114篇 |
肿瘤学 | 6837篇 |
出版年
2023年 | 578篇 |
2022年 | 1092篇 |
2021年 | 2159篇 |
2020年 | 1325篇 |
2019年 | 1990篇 |
2018年 | 2451篇 |
2017年 | 1803篇 |
2016年 | 2158篇 |
2015年 | 2504篇 |
2014年 | 3299篇 |
2013年 | 4353篇 |
2012年 | 6731篇 |
2011年 | 6784篇 |
2010年 | 4018篇 |
2009年 | 3665篇 |
2008年 | 6012篇 |
2007年 | 6487篇 |
2006年 | 6024篇 |
2005年 | 5981篇 |
2004年 | 5578篇 |
2003年 | 4973篇 |
2002年 | 4960篇 |
2001年 | 1927篇 |
2000年 | 1880篇 |
1999年 | 1722篇 |
1998年 | 1238篇 |
1997年 | 1014篇 |
1996年 | 824篇 |
1995年 | 836篇 |
1994年 | 718篇 |
1993年 | 648篇 |
1992年 | 1198篇 |
1991年 | 1107篇 |
1990年 | 1060篇 |
1989年 | 997篇 |
1988年 | 886篇 |
1987年 | 846篇 |
1986年 | 853篇 |
1985年 | 853篇 |
1984年 | 692篇 |
1983年 | 603篇 |
1982年 | 573篇 |
1981年 | 462篇 |
1980年 | 411篇 |
1979年 | 542篇 |
1978年 | 439篇 |
1977年 | 397篇 |
1975年 | 341篇 |
1974年 | 386篇 |
1973年 | 365篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Sonographic evaluation of gallbladder kinetics: in vitro and in vivo comparison of different methods to assess gallbladder emptying. 总被引:3,自引:0,他引:3
Bernd Wedmann Gabriele Schmidt Martin Wegener Christoph Coenen Dieter Ricken Cornelia Drge 《Journal of clinical ultrasound : JCU》1991,19(6):341-349
In an in vitro study, 10 gallbladders of adult pigs and 6 gallbladders of lambs, all removed immediately after slaughtering, were stimulated in a water bath by electric means to induce active contraction. Gallbladder emptying was followed by ultrasonography employing five measurement procedures: (1) gallbladder width, (2) longitudinal planimetry, (3) transverse planimetry, (4) ellipsoid method, and (5) sum of cylinders method. In an in vivo investigation, gallbladder emptying of 30 volunteers (12 healthy subjects, 18 diabetics) was evaluated in the same way after ingestion of a fatty meal. Gallbladder width was found to be unsuitable to estimate the decrease in gallbladder volume due to a nonlinear relation of the parameters. Longitudinal planimetry tended to be less valid than transverse planimetry in assessing gallbladder volume reduction. The most valid estimation of gallbladder volume decreases was obtained by the two three-dimensional procedures. However, in neither in vitro nor in vivo could a significant difference between the sum of cylinders method and the ellipsoid method in determining relative volume reduction be established. We conclude that a three-dimensional measurement procedure should be used for valid assessments of gallbladder motility. However, according to our data there is no advantage in using the time-consuming sum of cylinders method compared to the simple ellipsoid method. 相似文献
102.
103.
104.
Fiber-reinforced resin composites (FRCs) have been used to make frameworks to support particulate resin composite veneers in the replacement of missing teeth. Both prosthetic laboratory-fabricated and chairside-fabricated approaches have been used with varying degrees of success. The chairside FRC fixed partial denture has been mainly used for anterior tooth replacement where the emphasis is on esthetics rather than withstanding occlusal load. This article focuses on the use of this technology in the chairside replacement of premolars. The concept of using a prefabricated framework is described in detail. This approach allows for the efficient delivery of a consistently made chairside prosthesis. This is in contrast with the time-consuming and less consistent result of FRC framework fabrication directly in the mouth. The goal for this concept is to use a premade framework finalized by the provider at chairside to provide medium- to long-term posterior tooth replacement, with minimal abutment tooth reduction. 相似文献
105.
A case of esthesioneuroblastoma with an unusual clinical and radiographic presentation is reported. The presenting symptoms as well as the computed tomographic examination were compatible with a primary intracranial mass. 相似文献
106.
Summary Bayesian analysis is given of a random effects binary probit model that allows for heteroscedasticity. Real and simulated examples illustrate the approach and show that ignoring heteroscedasticity when it exists may lead to biased estimates and poor prediction. The computation is carried out by an efficient Markov chain Monte Carlo sampling scheme that generates the parameters in blocks. We use the Bayes factor, cross‐validation of the predictive density, the deviance information criterion and Receiver Operating Characteristic (ROC) curves for model comparison. 相似文献
107.
Further evidence of dopamine transporter dysregulation in ADHD: a controlled PET imaging study using altropane. 总被引:4,自引:0,他引:4
Thomas J Spencer Joseph Biederman Bertha K Madras Darin D Dougherty Ali A Bonab Elijahu Livni Peter C Meltzer Jessica Martin Scott Rauch Alan J Fischman 《Neuropsychopharmacology》2007,62(9):1059-1061
BACKGROUND: The dopamine transporter (DAT) is known to be a key regulator of dopamine, and recent studies of genetics, treatment, and imaging have highlighted the role of DAT in attention-deficit/hyperactivity disorder (ADHD). The findings of in vivo neuroimaging of DAT in ADHD have been somewhat discrepant, however. METHOD: Dopamine transporter binding was measured using a highly selective ligand (C-11 altropane) and positron emission tomography (PET). The sample consisted of 47 well-characterized, treatment-na?ve, nonsmoking, non-comorbid adults with and without ADHD. Additionally, control subjects had few symptoms of ADHD. RESULTS: Results showed significantly increased DAT binding in the right caudate in adults with ADHD compared with matched control subjects without this disorder. CONCLUSIONS: These results confirm abnormal DAT binding in the striatum of adults with ADHD and provide further support that dysregulation of DAT may be an important component of the pathophysiology of ADHD. 相似文献
108.
109.
Kimberly A. Varker Edward W. Martin Dori Klemanski Bryan Palmer Manisha H. Shah Mark Bloomston 《Journal of gastrointestinal surgery》2007,11(12):1680-1685
Background
Transarterial chemoemobolization (TACE) is commonly used to treat metastatic carcinoid tumors; however, the management of
progressive disease is less clear. We sought to determine if patients with disease progression after TACE would benefit from
repeat TACE.
Methods
The records of 27 patients undergoing repeat TACE for radiologic or symptomatic progression after TACE for metastatic carcinoid
were reviewed and compared to 122 undergoing first TACE. Overall and progression-free survivals were estimated by the Kaplan–Meier
method.
Results
Mean disease-free interval after first TACE was 11.8 months. Radiologic response was observed in 61% compared to 82% after
first TACE (p = 0.058); hormone response in 64% compared to 80% (p = 0.159); and symptomatic response in 77% compared to 92% (p = 0.053). The complication rate after repeat TACE was lower than after first TACE (p = 0.03). Median overall survival was similar after repeat (28.1 months) and first TACE (33.3 months) (p = 0.53). Progression-free survival was shorter after repeat TACE but not significantly so. No factor examined could predict
survival after repeat TACE.
Conclusion
Repeat TACE for patients with hepatic carcinoid metastases failing first TACE or having evidence of disease progression is
safe and offers a viable treatment option.
Presented at the 48th Annual Meeting of The Society for Surgery of the Alimentary Tract, Washington, DC, May, 2007. 相似文献
110.