全文获取类型
收费全文 | 6364篇 |
免费 | 643篇 |
国内免费 | 16篇 |
专业分类
耳鼻咽喉 | 43篇 |
儿科学 | 300篇 |
妇产科学 | 192篇 |
基础医学 | 986篇 |
口腔科学 | 55篇 |
临床医学 | 681篇 |
内科学 | 1222篇 |
皮肤病学 | 88篇 |
神经病学 | 610篇 |
特种医学 | 283篇 |
外科学 | 584篇 |
综合类 | 57篇 |
一般理论 | 5篇 |
预防医学 | 742篇 |
眼科学 | 126篇 |
药学 | 494篇 |
中国医学 | 25篇 |
肿瘤学 | 530篇 |
出版年
2023年 | 59篇 |
2022年 | 82篇 |
2021年 | 148篇 |
2020年 | 95篇 |
2019年 | 157篇 |
2018年 | 173篇 |
2017年 | 149篇 |
2016年 | 134篇 |
2015年 | 147篇 |
2014年 | 223篇 |
2013年 | 273篇 |
2012年 | 424篇 |
2011年 | 449篇 |
2010年 | 259篇 |
2009年 | 231篇 |
2008年 | 386篇 |
2007年 | 379篇 |
2006年 | 371篇 |
2005年 | 367篇 |
2004年 | 376篇 |
2003年 | 335篇 |
2002年 | 285篇 |
2001年 | 106篇 |
2000年 | 92篇 |
1999年 | 95篇 |
1998年 | 112篇 |
1997年 | 64篇 |
1996年 | 50篇 |
1995年 | 41篇 |
1994年 | 50篇 |
1993年 | 53篇 |
1992年 | 63篇 |
1991年 | 62篇 |
1990年 | 63篇 |
1989年 | 68篇 |
1988年 | 61篇 |
1987年 | 58篇 |
1986年 | 45篇 |
1985年 | 33篇 |
1984年 | 47篇 |
1983年 | 24篇 |
1982年 | 20篇 |
1981年 | 17篇 |
1980年 | 24篇 |
1979年 | 31篇 |
1978年 | 19篇 |
1977年 | 20篇 |
1975年 | 17篇 |
1974年 | 23篇 |
1973年 | 24篇 |
排序方式: 共有7023条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
Uptake of iodine-123 MIBG by pheochromocytomas, paragangliomas, and neuroblastomas: a histopathological comparison 总被引:2,自引:0,他引:2
J Bomanji D A Levison W D Flatman T Horne P M Bouloux G Ross K E Britton G M Besser 《Journal of nuclear medicine》1987,28(6):973-978
The percentage uptake of [123I]metaiodobenzylguanidine (MIBG) by tumors of the paraganglion system is compared with the number of neurosecretory granules (assessed by both light and electron microscopy) in the subsequently resected tumors in six patients. Iodine-123 MIBG was injected intravenously; the tumor uptake of [123I]MIBG varied between 0.001% and 0.14% of the injected dose per gram of tumor tissue at 22 hr. The number of neurosecretory granules in tissue sections was scored on a scale of I-III. A direct proportional correlation was found between the percentage uptake of [123I]MIBG by the tumor and the number of neurosecretory granules in the tissue sections but not with plasma or urinary catecholamines. This technique for imaging reflects the storage status of the tumor better than plasma and urinary catecholamine measurements. 相似文献
5.
Leonard A. Jason PhD Steven B. Pokorny PhD Monica Adams MPH Annie Topliff MA Courtney Harris BA Yvonne Hunt PhD 《The American journal on addictions / American Academy of Psychiatrists in Alcoholism and Addictions》2009,18(5):367-374
This study evaluated the effects of tobacco Purchase, Use and Possession (PUP) laws on student perceptions of adolescent tobacco use within towns and schools. Twenty‐four towns were randomly assigned into two conditions, the experimental condition (E PUP) involved efforts to increase both PUP law enforcement and reduce minors' access to commercial sources of tobacco, whereas the control condition (C) focused only on efforts to reduce minors' access to commercial sources of tobacco. A hierarchical linear modeling analytical approach was selected due to the multilevel data and nested design. The present study found that over time, youth in the experimental PUP condition observed less youth tobacco usage at school and in their town, and perceived lower rates of tobacco among their peers at school and among friends than youth in the control condition. The findings suggest that PUP law enforcement might be used to strengthen community norms against youth tobacco use. 相似文献
6.
7.
The requirements, problems and progress of radioimmunotherapy in the management of certain malignancies are described. The future prospects using a two- or three-stage approach are promising. 相似文献
8.
Israel Liberzon Stephan F Taylor K Luan Phan Jennifer C Britton Lorraine M Fig Joshua A Bueller Robert A Koeppe Jon-Kar Zubieta 《Neuropsychopharmacology》2007,61(9):1030-1038
BACKGROUND: Functional neuroimaging studies have detected abnormal limbic and paralimbic activation to emotional probes in posttraumatic stress disorder (PTSD), but few studies have examined neurochemical mechanisms that underlie functional alterations in regional cerebral blood flow. The mu-opioid neurotransmitter system, implicated in responses to stress and suppression of pain, is distributed in and is thought to regulate the function of brain regions that are implicated in affective processing. METHODS: Here we examined the micro-opioid system with positron emission tomography and the micro-opioid receptor-selective radiotracer [11C] carfentanil in 16 male patients with PTSD and two non-PTSD male control groups, with (n = 14) and without combat exposure (n = 15). Differences in micro-opioid receptor binding potential (BP2) were detected within discrete limbic and paralimbic regions. RESULTS: Relative to healthy controls, both trauma-exposed groups had lower micro-opioid receptor BP2 in extended amygdala, nucleus accumbens, and dorsal frontal and insular cortex but had higher BP2 in the orbitofrontal cortex. PTSD patients exhibited reduced BP2 in anterior cingulate cortex compared with both control groups. Micro-opioid receptor BP2 in combat-exposed subjects without PTSD was lower in the amygdala but higher in the orbitofrontal cortex compared with both PTSD patients and healthy controls. CONCLUSIONS: These findings differentiate the general response of the micro-opioid system to trauma from more specific changes associated with PTSD. 相似文献
9.
10.
Annie Mathieu Stéphanie Mazza Dominique Petit Anne Décary Jessica Massicotte-Marquez Jacques Malo Jacques Montplaisir 《Clinical neurophysiology》2007,118(7):1538-1544
OBJECTIVE: The aim of this study was to determine whether EEG slowing is more pronounced in older than younger OSAS patients and to verify whether this cortical slowing is correlated to daytime performance, respiratory perturbation and sleep fragmentation. METHODS: Twelve young OSAS patients (mean age 38.2+/-2.0 y) and 13 older OSAS patients (mean age 62.2+/-1.9 y) along with 13 young controls (mean age 35.8+/-2.0 y) and 14 older controls (mean age 60.2+/-2.0 y) underwent a polysomnographic evaluation followed by a waking EEG recording. As a global index of cortical slowing, a ratio of slow-to-fast frequencies was calculated in all cortical regions. Daytime performance was assessed using the four choice reaction time test. RESULTS: Differences in waking EEG and in daytime performance were analyzed by ANOVAs with Group and Age as factors. Waking EEG did not yield a Group by Age interaction. OSAS patients had higher ratios across all regions than controls. Similarly, daytime performance revealed no Group by Age interaction. However, OSAS patients showed more lapses than controls and older subjects were slower than younger subjects. CONCLUSIONS: Our results indicate that age does not interact with OSAS to worsen the severity of cortical slowing, but age can add to the OSAS effect to worsen daytime performance deficits in OSAS patients. SIGNIFICANCE: The daytime performance deficits observed particularly in elderly OSAS patients warrant a careful clinical assessment of these patients to prevent accidents and injuries. 相似文献