全文获取类型
收费全文 | 30402篇 |
免费 | 3270篇 |
国内免费 | 1035篇 |
专业分类
耳鼻咽喉 | 212篇 |
儿科学 | 386篇 |
妇产科学 | 226篇 |
基础医学 | 2371篇 |
口腔科学 | 391篇 |
临床医学 | 4839篇 |
内科学 | 4259篇 |
皮肤病学 | 93篇 |
神经病学 | 6591篇 |
特种医学 | 5877篇 |
外国民族医学 | 12篇 |
外科学 | 2147篇 |
综合类 | 3526篇 |
现状与发展 | 1篇 |
预防医学 | 657篇 |
眼科学 | 332篇 |
药学 | 1139篇 |
7篇 | |
中国医学 | 338篇 |
肿瘤学 | 1303篇 |
出版年
2024年 | 191篇 |
2023年 | 748篇 |
2022年 | 1470篇 |
2021年 | 1866篇 |
2020年 | 1702篇 |
2019年 | 1648篇 |
2018年 | 1341篇 |
2017年 | 1383篇 |
2016年 | 1286篇 |
2015年 | 1244篇 |
2014年 | 2116篇 |
2013年 | 1921篇 |
2012年 | 1613篇 |
2011年 | 1791篇 |
2010年 | 1452篇 |
2009年 | 1492篇 |
2008年 | 1450篇 |
2007年 | 1382篇 |
2006年 | 1347篇 |
2005年 | 1197篇 |
2004年 | 920篇 |
2003年 | 861篇 |
2002年 | 785篇 |
2001年 | 607篇 |
2000年 | 387篇 |
1999年 | 341篇 |
1998年 | 318篇 |
1997年 | 293篇 |
1996年 | 320篇 |
1995年 | 259篇 |
1994年 | 237篇 |
1993年 | 174篇 |
1992年 | 104篇 |
1991年 | 86篇 |
1990年 | 60篇 |
1989年 | 59篇 |
1988年 | 49篇 |
1987年 | 36篇 |
1986年 | 28篇 |
1985年 | 37篇 |
1984年 | 25篇 |
1983年 | 22篇 |
1982年 | 18篇 |
1981年 | 8篇 |
1980年 | 10篇 |
1979年 | 9篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1973年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Stefano Tamburin Antonio Fiaschi Domenico Idone Piergiorgio Lochner Paolo Manganotti Giampietro Zanette 《Movement disorders》2003,18(11):1316-1324
Hyperexcitability of the motor system has been reported in Parkinson's disease (PD). We evaluate how cutaneous afferents modulate motor excitability in PD patients and whether abnormal modulation is correlated to parkinsonian symptoms. Digital stimulation causes abnormal enhancement of motor responses in patients. This effect may be one of the features of motor hyperexcitability in PD. Cutaneomotor hyperexcitability correlates with clinical scores, suggesting that abnormal processing of cutaneous inputs might contribute to the pathogenesis of parkinsonian symptoms. 相似文献
93.
94.
Adolf Pfefferbaum Edith V. Sullivan Margaret J. Rosenbloom Paula K. Shear Daniel H. Mathalon Kelvin O. Lim 《Psychiatry Research: Neuroimaging》1993,50(4):257-274
This cross-sectional study used a semi-automated analysis technique to quantify regional brain cerebrospinal fluid (CSF) volumes derived from computed tomography (CT) in 84 healthy men ranging from 21 to 82 years of age and 28 patients meeting Research Diagnostic Criteria for alcohol dependence. The goals were to replicate an earlier CT study of an independent sample of alcoholic and control subjects (Pfefferbaum et al., 1988a; Zipursky et al., 1988) and to compare CT assessments of brain changes with magnetic resonance imaging (MRI) assessments made in the same alcoholic patients (Pfefferbaum et al., 1992). Regional brain changes associated with normal aging were derived by regression analysis, using CT data collected from the healthy control subjects. As in the earlier CT study and in the concurrent MRI study, ventricular and sulcal CSF volumes in alcoholic patients were greater than would be expected for their age. Furthermore, the present CT study replicated the previous CT and MRI findings of a positive relationship between age and CSF volume enlargement in alcoholic patients over and above the normal age-related increase in CSF volume, suggesting greater vulnerability of the aging brain to alcohol. Comparison of CT-and MRI-derived estimates of ventricular and cortical sulcal volume revealed high correlations (>0.80). MRI and CT produced similar absolute ventricular volumes, while MRI produced larger sulcal volume estimates than did CT. The difference in sulcal volume estimate may be due to differences between CT and MRI in slice thickness and sensitivity to partial volume effects. 相似文献
95.
Hiroyuki Ishizu Masatoshi Takahashi Yukifumi Kondo Akihiko Kataoka Takashi Nakamura Kuniaki Okada Hiroyuki Masuko Yasunori Nishida Hideaki Ogawa Ryoji Yokoyama Yutaka Kimura 《Surgery today》1997,27(3):285-287
Magnetic resonance cholangiopancreatography (MRCP) was performed in 35 patients to evaluate the feasibility of its use as a postsurgical imaging technique after resection of the pancreas. The surgical procedures performed were: pancreatoduodenectomy in 22 patients, segmental pancreatectomy in 1, distal pancreatectomy in 7, and pyroluspreserving pancreatoduodenectomy in 5. The pancreatic duct was shown in its entirety in 24 of the 35 patients (68.6%) and was partially visualized in 8 patients (22.9%), but the intrahepatic and extrahepatic bile ducts were visualized completely in all patients. Furthermore, MRCP was able to demonstrate lesions in 3 of 6 patients who had shown clinical evidence of recurrence. The visualization of the pancreatic and bile duct system was satisfactory despite anatomical changes brought about by resection of the pancreas. Thus, we conclude that MRCP is an appropriate follow-up screening test for patients with suspected abnormalities of the biliary and pancreatic duct system. 相似文献
96.
97.
Gradient acoustic noise has been measured and characterized for an epoxy-potted, shielded gradient assembly in a 1.5 T MRI system. Noise levels vary by 10 dB or more as a function of longitudinal position in the scanner and reflect the pattern of forces applied to the gradient assembly. The noise level increases slightly (1–3 dB) with a patient in the scanner. The spectrum of the noise is similar (but not identical) to the spectrum of the input signal. A gradient-pulse-to-acoustic-noise transfer function was obtained by using a white noise voltage input to the gradient system. The transfer function enabled us to accurately predict acoustic noise output for a pulse sequence consisting of a series of trapezoidal pulses on a single axis and for a clinical fast spin echo sequence with gradients present on all three axes. 相似文献
98.
T.-H. ZHOU X.-H. REN D.-L. YIN Y.-L. WU M. Li C.-Z. Lu D.-C. Wu Y.-Q. Wu Y.-Q. PENG Y.-P. WANG L. MA G. PEI 《Acta anaesthesiologica Scandinavica》1997,41(8):1077-1079
Congenital analgesia is a rare genetic disorder. We report here that a 12-year-old boy was able to recover from congenital insensitivity to pain. Neurological examinations revealed that there was a 'stocking' distribution of pain decrement on the lower extremities under the patient's knee joints. Magnetic Resonance Imaging (MRI) of his brain showed gyrus thinning with sulcus widening at both sides of the parietal lobe. Southern blot hybridization probed with cDNAs of various opioid receptors did not detect any significant abnormality. Our results suggest that this rare case may not be genetically determined. 相似文献
99.
Florian A Kagerer Jeff J Summers Winston D Byblow Bruce Taylor 《Movement disorders》2003,18(8):919-927
In 6 patients with Parkinson's disease (PD) and 6 age-matched controls, transcranial magnetic stimulation was applied at 56 regions over the motor cortex and premotor cortex of each hemisphere, with the first dorsal interosseous (FDI) muscle of both hands activated at 15% maximum voluntary contraction during stimulation. For each site, motor evoked potential (MEP) landmarks were recovered, including MEP amplitude, MEP onset latency, and silent period duration. Scaled MEP amplitudes were used to construct individual cortical maps of the FDI muscles. The maps revealed an anterior displacement of the muscle representation in PD patients. This anterior shift over motor cortical areas may reflect increased contributions of corticocortical connections between motor cortex and premotor cortical areas, possibly enhanced by the visual feedback aspect of the task. These alterations may reflect adaptations to the impairments in striatocortical circuits in PD. 相似文献
100.
Ronald G. Pratt Jie Zheng Brent K. Stewart Yoseph Shiferaw Anthony J. McGoron Ranasinghage C. Samaratunga Stephen R. Thomas 《Magnetic resonance in medicine》1997,37(2):307-313
A limited flip angle gradient-echo 3D volume acquisition imaging protocol for mapping partial pressure of oxygen (pO2) in perfluorocarbon compounds (PFCs) at low field (0.14 T) is presented. The pO2 measurement method is based on the paramagnetic effect of dissolved molecular oxygen (O2) which reduces the PFC 19F T1? Specific objectives related to imaging of PFCs through use of the protocol include improved image signal-to-noise characteristics and elimination of 19F chemical shift artifacts. A parametric Wiener deconvolution filtering algorithm is used for suppression of 19F chemical shift artifacts. Application of the protocol is illustrated in a series of calculated pO2 maps of a gas equilibrated, multi-chamber phantom containing perfluorotributylamine (FC-43). The utility of the protocol is demonstrated in vivo through images of a commercially available perfluorocarbon based blood substitute emulsion containing FC-43 sequestered in the liver and spleen of a rat. 相似文献