全文获取类型
收费全文 | 46767篇 |
免费 | 3343篇 |
国内免费 | 188篇 |
专业分类
耳鼻咽喉 | 375篇 |
儿科学 | 1506篇 |
妇产科学 | 1201篇 |
基础医学 | 6594篇 |
口腔科学 | 590篇 |
临床医学 | 5031篇 |
内科学 | 9770篇 |
皮肤病学 | 876篇 |
神经病学 | 5540篇 |
特种医学 | 1122篇 |
外科学 | 4163篇 |
综合类 | 380篇 |
一般理论 | 58篇 |
预防医学 | 5667篇 |
眼科学 | 617篇 |
药学 | 2975篇 |
中国医学 | 86篇 |
肿瘤学 | 3747篇 |
出版年
2024年 | 59篇 |
2023年 | 650篇 |
2022年 | 1086篇 |
2021年 | 2143篇 |
2020年 | 1297篇 |
2019年 | 1772篇 |
2018年 | 2034篇 |
2017年 | 1362篇 |
2016年 | 1515篇 |
2015年 | 1659篇 |
2014年 | 2024篇 |
2013年 | 2621篇 |
2012年 | 4194篇 |
2011年 | 4151篇 |
2010年 | 2103篇 |
2009年 | 1844篇 |
2008年 | 2943篇 |
2007年 | 2905篇 |
2006年 | 2773篇 |
2005年 | 2569篇 |
2004年 | 2278篇 |
2003年 | 2034篇 |
2002年 | 1731篇 |
2001年 | 192篇 |
2000年 | 142篇 |
1999年 | 207篇 |
1998年 | 347篇 |
1997年 | 261篇 |
1996年 | 212篇 |
1995年 | 175篇 |
1994年 | 124篇 |
1993年 | 119篇 |
1992年 | 70篇 |
1991年 | 66篇 |
1990年 | 61篇 |
1989年 | 64篇 |
1988年 | 58篇 |
1987年 | 39篇 |
1986年 | 41篇 |
1985年 | 37篇 |
1984年 | 48篇 |
1983年 | 48篇 |
1982年 | 34篇 |
1981年 | 42篇 |
1980年 | 28篇 |
1979年 | 21篇 |
1978年 | 14篇 |
1977年 | 24篇 |
1975年 | 10篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
A restricted field of view (rFOV) approach for imaging a dynamic time series of volumes of limited spatial extent within a larger subject is described. The shorter readout with rFOV-MRI can be exploited to either limit image artifacts or increase spatial resolution. To accomplish rFOV imaging of a multislice volume for a dynamic series, an outer volume suppression (OVS) preparation that saturates signal external to a cylinder through the subject is followed by slice-selective excitation and a spiral readout. The pass- and stopband efficiencies of the OVS in an agar gel phantom were 97% (+/-1.5%) and 3% (+/-1%), respectively. Profiles of the temporal signal-to-noise ratio (SNR) were measured in a phantom and an adult brain. The rFOV sequence reduced distortions from off-resonance signal and T2*-induced blurring compared to a conventional sequence. Sequence utility is demonstrated for high-resolution rFOV functional MRI (fMRI) in the visual cortex. The rFOV sequence may prove to be useful for other multislice dynamic and high-resolution imaging applications. 相似文献
83.
84.
A. C. Leon M. Katherine Shear Laura Portera G. L. Klerman 《Social psychiatry and psychiatric epidemiology》1992,27(2):78-82
Summary The DSM-III-R incorporates both distress (symptoms) and disability (impairment) in the definition of a psychiatric disorder. In psychiatric research there is a wide array of instruments used to measure symptom severity, but a limited selection for the assessment of impairment. The psychometric properties of one such instrument, The Sheehan Disability Scale (Sheehan 1983), are evaluated in this paper. The data analyzed come from two studies of patients with panic disorder, the Cross National Collaborative Panic Study-Phase I and the Panic Depression Study. In this report both the alpha coefficients and factor analyses indicate that the reliability of the scale is acceptable. The factor structure of the items and the sensitivity to change of their composite demonstrate satisfactory construct validity. The criterion-related validity is substantiated by the significant relationship between symptomatology and impairment. These analyses were limited to patients with panic disorder. Further work is needed to evaluate the instrument in assessing patients with other disorders. 相似文献
85.
86.
87.
88.
89.
Laura J. Cohen 《Journal of Midwifery & Women's Health》1992,37(2):91-94
Bibliotherapy is the use of literature to help heal. It can be an effective intervention for nurse-midwives to use with clients. Presented is a discussion of how to do bibliotherapy and an annotated bibliography of resources. 相似文献
90.
Jody Tanabe Jason R Tregellas Laura F Martin Robert Freedman 《Neuropsychopharmacology》2006,59(8):754-761
BACKGROUND: Abnormal smooth pursuit eye movement (SPEM) in schizophrenic patients is a well known phenomenon, but the neurophysiological mechanisms underlying the deficit are unknown. Nicotine temporarily improves SPEM and has been associated with reduced hippocampal hemodynamic activity in schizophrenics. Nicotine's effect on brain activity in control subjects performing SPEM has not been studied. The purpose of this work was to determine if nicotine differentially affects brain activity in schizophrenic and control subjects during pursuit eye tracking. METHODS: 16 subjects with schizophrenia and 16 control subjects underwent functional MR imaging during SPEM after receiving placebo or nicotine gum. Four brain regions were analyzed for main effects of group, drug, and interactions: hippocampus, cingulate gyrus, frontal eye fields, and area MT. RESULTS: Nicotine reduced hippocampal activity in both groups, but the effect was greater in control subjects. A group by drug interaction was observed in the anterior cingulate gyrus, where nicotine decreased activity in control subjects and increased activity in schizophrenic subjects. There were no significant effects of group, drug, or interactions in frontal eye fields or area MT. CONCLUSIONS: Nicotine may improve SPEM performance in people with schizophrenia through cholinergic stimulation of the hippocampus and cingulate gyrus. Potential mechanisms include improved inhibitory function and attention. 相似文献