全文获取类型
收费全文 | 47494篇 |
免费 | 3315篇 |
国内免费 | 941篇 |
专业分类
耳鼻咽喉 | 212篇 |
儿科学 | 519篇 |
妇产科学 | 508篇 |
基础医学 | 4307篇 |
口腔科学 | 495篇 |
临床医学 | 4273篇 |
内科学 | 3750篇 |
皮肤病学 | 670篇 |
神经病学 | 8315篇 |
特种医学 | 1585篇 |
外国民族医学 | 291篇 |
外科学 | 2487篇 |
综合类 | 6967篇 |
现状与发展 | 1篇 |
一般理论 | 2篇 |
预防医学 | 3521篇 |
眼科学 | 409篇 |
药学 | 7888篇 |
8篇 | |
中国医学 | 3230篇 |
肿瘤学 | 2312篇 |
出版年
2024年 | 54篇 |
2023年 | 498篇 |
2022年 | 737篇 |
2021年 | 1231篇 |
2020年 | 1119篇 |
2019年 | 1389篇 |
2018年 | 1543篇 |
2017年 | 1286篇 |
2016年 | 1159篇 |
2015年 | 1078篇 |
2014年 | 5685篇 |
2013年 | 5008篇 |
2012年 | 3654篇 |
2011年 | 3661篇 |
2010年 | 4666篇 |
2009年 | 4475篇 |
2008年 | 2700篇 |
2007年 | 1605篇 |
2006年 | 1308篇 |
2005年 | 1016篇 |
2004年 | 903篇 |
2003年 | 762篇 |
2002年 | 599篇 |
2001年 | 589篇 |
2000年 | 480篇 |
1999年 | 454篇 |
1998年 | 385篇 |
1997年 | 397篇 |
1996年 | 393篇 |
1995年 | 308篇 |
1994年 | 257篇 |
1993年 | 224篇 |
1992年 | 198篇 |
1991年 | 186篇 |
1990年 | 185篇 |
1989年 | 131篇 |
1988年 | 130篇 |
1987年 | 136篇 |
1986年 | 98篇 |
1985年 | 164篇 |
1984年 | 164篇 |
1983年 | 129篇 |
1982年 | 136篇 |
1981年 | 90篇 |
1980年 | 101篇 |
1979年 | 74篇 |
1978年 | 44篇 |
1977年 | 44篇 |
1976年 | 42篇 |
1975年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
71.
经病理确诊的527例原发性支气管肺癌(PBC)(1972~1987)中,PBC伴其它部位多原发癌(MPC)25例(4.7%)。其中双原发肺癌(DPBC)、12例(2.3%),PBC伴消化道癌6例(1.14%)。25例中共有原发癌灶52个,其中2例为3原发癌;同期组6例(其中DPBC 4例),后期组19例(其中14例间隔3年以上,内2例分别间隔14年及25年)。组织类型相同者8例,不同者4例。 25例MPC特点如下:1.55岁以上20例(80%);2.24例(96%)第2原发癌为1980年后发现;3.第2原发癌为肺癌者23例(92%);4.双原发肺癌12例(48%)。上述特点说明80年代老年人中MPC,尤其是肺癌发病率增高。 本文着重对第2原发肺癌的影像学表现和鉴别诊断进行讨论。 相似文献
72.
Purpose. To estimate disease activity in patients with systemic sclerosis using contrast-enhanced MRI of the skin.
Material and Methods. In a pre-study, sequences of a low-field (0.2 T) scanner (Artoscan, Esaote, Genova, Italy) were optimized for detection of
intravenous contrast (0.1 mmol/l Gd-DTPA) in six patients with the autoimmune disease systemic scleroderma. Based on the results
of the pre-study, 17 patients with scleroderma (7 sclerotic/10 active inflammatory disease) were scanned using gradient-spoiled
3D GRE sequences (FA 90 °, TR 100 ms, TE 18 ms), which had been established as most sensitive for intravenous contrast. Contrast
enhancement of the skin was determined quantitatively by contrast-to-noise ratios (CNR), comparing post- to pre-contrast and
dynamic scans (for 6 min, 1 acquisition/min). Patients in the chronic state with sclerodactylia and active inflammation of
the hands were considered separately and compared to a control group (n = 10) matched according to age.
Results. CNR increase after intravenous contrast was significantly higher in patients with active disease (86 ± 16 % increase) than
sclerosing disease (29 ± 3 %, p < 0.05) and the control group (4 ± 2 %, p < 0.05). The dynamic examination showed a significantly slower decrease after the peak rise in the first minute in patients
with active disease (CNR 15.4 ± 0.7 to 14.2 ± 1.4) than in those with chronic disease (14.1 ± 0.5 to 11.3 ± 0.9, p < 0.05).
Discussion. Capillary leakage is the most likely explanation for the increased enhancement in patients with active scleroderma. Using
sequences optimized for contrast detection, disease activity in the course of scleroderma and response to therapy can be determined
by MRI in the future.
相似文献
73.
74.
Autonomic dysfunction is frequent in patients with multiple sclerosis (MS). The sympathetic skin response (SSR) and the R-R interval variation (RRIV) are simple electrophysiologic tests for the assessment of central and peripheral autonomic disturbances. Both tests were performed in 60 patients with clinically definite MS and 30 controls. The SSR was recorded simultaneously from both upper and both lower limbs. In all volunteers normal responses were recorded from the four limbs, but 39 patients (65%) showed abnormal responses in at least one limb. The reduction in amplitude of the response was correlated with patients' EDSS. In individual limbs, the SSR amplitude correlated with weakness, spasticity and cerebellar dysfunction, but was not sufficiently related to the deep sensory loss. The RRIV was abnormal in 48 MS patients (80%), as compared to the controls, but showed no significant relationship either to the EDSS or to the SSR. The sensitivity of SSR and RRIV is high and comparable with that of visual and somatosensory evoked potentials. 相似文献
75.
S. A. Baxendale W. van Paesschen P. J. Thompson A. Connelly J. S. Duncan W. F. Harkness S. D. Shorvon 《Epilepsia》1998,39(2):158-166
Summary: Purpose: Quantitative MRI techniques provide an unparalleled opportunity to examine in vivo the relationship between the extent and laterality of hippocampal pathology and associated neuropsychological deficits. The purpose of this study was to examine the nature of the relationship between quantitative measures of hippocampal pathology and neuropsychological measures, using a multivariate approach. Methods: We examined the relationship between two MRI measures of hippocampal structure; hippocampal volumes (HCvol) and T2 relaxation times (HCT2), and memory performance, in 80 presurgical temporal lobe epilepsy patients. Results: As a group, patients with left hippocampal sclerosis (LHS) performed more poorly that those with right hippocampal sclerosis (RHS) on immediate and delayed prose recall. In the group as a whole, right hippocampal volume was significantly correlated with the delayed recall of a complex figure. None of the verbal memory test scores were significantly correlated with the right or left HCvol or HCT2 measures. However, stepwise multiple regression analyses indicated that up to a third of the variation in specific test scores could be explained by the quantitative MRI hippocampal measures in conjunction with chronological age, and age at onset of habitual epilepsy. Left hippocampal measures explained 24% of the variance in the story-recall tasks, while right hippocampal measures explained 18% of the variance in a design-learning task and 32% of the variance in a figure-recall task. Conclusions: Our results provide some support for the lateralised model of material specific memory deficits, but suggest that a number of demographic and epilepsy-related factors may interact with the extent and laterality of hippocampal pathology in shaping the nature of the associated neuropsychological deficit. 相似文献
76.
The geographic distribution of multiple sclerosis within the 95 Départements and the 21 Régions of France was defined from a 1986 nationwide prevalence series derived from questionnaires. This indicated a significant clustering of high frequency regions in the northeastern part of the country with most significantly low areas in the south and west. Distributions were similar to those for MS death rates by Département and Région for 1968–1977, indicating geographic stability over time; but there was also evidence of diffusion over time. The 1986 prevalence distribution was also compared with all published prevalence rates for communities of France. From all these resources we conclude that all of France falls within the "high frequency zone" for MS, that the nationwide prevalence rate is at least 50 per 100000 population, and that there is evidence of geographic clustering of the disease with temporal spread of the cluster. 相似文献
77.
M. Filippi A. Campi V. Martinelli C. Pereira G. Scotti G. Comi 《Acta neurologica Scandinavica》1995,92(2):178-182
Transitional progressive multiple sclerosis (MS) is quite an unusual form of presentation and course of the disease. A case with this progressive form is presented and brain MRI and MTI findings are discussed in relation to the possible insight they may provide for understanding the mechanisms that determine progressive disability in MS. 相似文献
78.
Pathogenesis of neuroimmunologic diseases 总被引:5,自引:0,他引:5
C. S. Constantinescu B. Milliard T. Fujioka M. K. Bhopale D. Calida Dr. A. M. Rostami 《Immunologic research》1998,17(1-2):217-227
Animal models of autoimmune diseases have greatly improved our current understanding of the pathogenesis of human autoimmunity
and have provided the potential for therapies based on manipulation of the immune system. In our laboratory, we have investigated
the immunopathogenesis of autoimmune diseases of the nervous system and muscle. We have developed immune-based approaches
for the suppression of experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis (MS), and experimental
autoimmune neuritis (EAN), a model for the Guillain-Barré syndrome (GBS). These approaches included induction of peripheral
tolerance, immunotoxin targeting of activated T cells, and cytokine manipulations. In addition, we identified the antigen
and characterized immunopathologically an autoimmune inflammatory disease of skeletal muscle, experimental autoimmune myositis
(EAM), a model for the human inflammatory muscle disease polymyositis. 相似文献
79.
S. Lehéricy F. Semah D. Hasboun D. Dormont S. Clémenceau O. Granat C. Marsault M. Baulac 《Neuroradiology》1997,39(11):788-796
MRI was performed in 222 consecutive adult patients with temporal lobe epilepsy of varying severity from January 1991 to
May 1993. The diagnosis of hippocampal sclerosis was established visually by three independent observers. The accuracy of
visual assessment of hippocampal asymmetry was compared with volumetric measurements. Neuropathological correlations were
obtained in 63 patients with refractory seizures. Temporal lobe abnormalities were observed in 180 patients (81 %) as follows:
hippocampal sclerosis in 122 (55 %); developmental abnormalities in 16 (7.2 %); tumours in 15 (6.8 %); scars in 11 (5 %);
cavernous angiomas in 10 (4.5 %); miscellaneous lesions in 6. MRI was normal or showed unrelated changes in 42 patients (19
%). Visual assessment correctly lateralised hippocampal sclerosis in 79 of the 84 patients measured (94 %). Temporal lobectomy
confirmed the MRI data (side and aetiology) in all 63 operated patients. Patients with normal MRI had an older age of seizure
onset and were more often drug-responsive than patients with hippocampal sclerosis. MRI showed temporal lobe abnormalities
in 81 % of epileptic patients with varying severity with good neuropathological correlation. Patients with normal MRI had
a less severe form of the disease.
Received: 19 August 1996 Accepted: 13 November 1996 相似文献
80.
A case report is presented in which a patient's initial complaint is of blurred vision after exercise (Uhthoffs symptom). Visual acuity and colour vision were found to be reduced after exercise. Additional neurological signs included homonymous scotomata and delayed visual evoked and somatosensory responses. Magnetic resonance imaging demonstrated multiple abnormal lesions in the brain. The significance of this symptom and its relationship to multiple sclerosis are discussed. 相似文献