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91.
Cone electroretinograms (ERGs), elicited by different color flashes under Ganzfeld conditions, were recorded from 6 patients with multiple evanescent white dot syndrome (MEWDS). All of the patients had normal color vision as determined by the Farnsworth Panel D-15 except for one who showed non-specific errors. The b-waves elicited from short wavelength sensitive (S-) cones were reduced more than the mixed long (L-) and middle (M-) wavelength sensitive cones in the affected eyes. The ratio of the S-cone b-wave amplitude of the affected eyes to that of the normal fellow eyes was significantly lower than the comparable ratio for the L- and M-cone ERG b-waves (p= 0.012). The S-cone ERGs recorded from 2 patients recovered to normal levels after their symptoms abated. These ERG results indicate that the S-cone system is more impaired than the L- and M-cone systems in the acute stage of MEWDS, and the changes in the S-cones may be reversible.  相似文献   
92.
目的:动态观察葛根素对新西兰大白兔视网膜缺血-再灌注损伤的保护作用.方法:新西兰大白兔30只随机分为缺血再灌注对照组和葛根素治疗实验组每组15只,各组右眼应用前房灌注加压法使前房内压力升高至120 mmHg(1 mmHg=0.133 kPa)维持60 min后再灌注,再灌注后第12、24、72 h分别记录其视网膜电图,与缺血前视网膜电图相比,观察a、b波的变化.葛根素治疗组在造成缺血前2 h予葛根素溶液玻璃体腔内注射,对照组予以玻璃体腔内注射等体积生理盐水.结果:两组右眼在结束造模后立即进行视网膜电图记录所得图形均呈直线;对照组与实验组再灌注各时段视网膜电图a波振幅差异无统计学意义(P》0.05);实验组各时段b波振幅明显高于对照组(P《0.001).结论:葛根素能促进缺血-再灌注损伤的视网膜功能恢复,对视网膜神经组织有保护作用.  相似文献   
93.
慢性甲醇中毒性视神经病变晚期视觉电生理改变   总被引:4,自引:1,他引:3  
目的:观察慢性甲醇中毒笥视神经病变晚期视觉电生理改变。方法:对21例(42只眼)患者随访2年并进行视觉电重量检测。结果:图形视觉诱发电位表现为P100潜伏期延长和P100波幅值降低,与正常对照组之间的差异非常显著(P〈0.01),闪光多膜电图的a、b波潜伏期和波幅值与正常对照组比较差异无显著性(P〉0.05)。结论:甲醇中毒的眼部损害部位主要在视神经,中毒早晚期的视觉电生理改变基本一致。  相似文献   
94.
We have characterized adaptive changes of inner retina function in response to sustained pattern stimulation in 32 normal subjects with an age range 23-77 years by measuring changes of the pattern electroretinogram (PERG) as a function of time. Contrast-reversal stimuli had square-wave profile in space and time, with peak spatial and temporal frequency and high contrast to maximize response amplitude. The PERG signal was sampled over 5 min with a resolution of 15 s. PERG signals were non-stationary, resulting in either progressive amplitude decline or even enhancement to a plateau, with a time course that could be well described by an exponential function with a time constant of 1-2 min. Higher initial amplitudes were generally associated with amplitude decline, and lower initial amplitudes with enhancement. The delta amplitude (plateau minus initial) was a linear function of the initial amplitude. The magnitude of delta decreased with decreasing initial amplitude and inverted its sign for initial amplitudes about 1/3 lower than the maximum initial amplitude measured, but still about 3-4 times larger than the noise. Amplitude decline was generally associated with phase lag, whereas amplitude enhancement was associated with phase advance. Altogether, PERG generators appear to slowly adjust their gain in order to keep their sustained activity at an intermediate level that is rather independent of the level of activity at stimulus onset. This behavior is reminiscent of a buffering mechanism, where glial cells may play a primary role. An energy-budget model of neural-vascular-glial interaction is provided together with an equivalent electrical circuit that accounts for the results.  相似文献   
95.
Variability in clinically measured photopic oscillatory potentials   总被引:2,自引:0,他引:2  
Oscillatory potentials found on the ascending phase of the electroretinogram b-wave probably originate in some element(s) of the inner plexiform layer. As oscillatory potentials are particularly sensitive to changes in retinal, and possibly choroidal, blood flow, they have been used extensively to provide clinical measures of the degree of retinal ischemia during the progression of diabetic retinopathy. Recent studies in our laboratories have disclosed previously unreported significant variability in the photopic oscillatory potentials on repeated measures even in tightly controlled conditions. The amplitude of five recordable light-adapted wavelets exhibited considerable intra- and inter-subject variability. Until further investigation can determine factors affecting standardization of testing, it appears that changes in oscillatory potential implicit times rather than in amplitudes are a better measurement in clinical neurophysiology.  相似文献   
96.
The oscillatory potentials (OPs) are probably generated in the proximal retina. The OPs of 20 visually inattentive infants and children were recorded. All 20 had evidence of abnormalities of the visual parts of the brain. The a- and b-waves, indices of distal retinal function, were normal in 10 patients, abnormal in the other 10. Among the patients with abnormal, attenuated a- and b-waves, OP amplitudes were more attenuated than among those with normal a- and b-waves. However, the timing of the OP wavelets was not correlated with distal retinal activity. These results suggest that in humans OP amplitude may be determined by inputs from the distal retina, but OP latency and periodicity are governed by processes within the proximal retina.  相似文献   
97.
This study describes the effects of penicillin G (PC-G) potassium, PC-G sodium, cloxacillin sodium (MCIPC), disodium sulbenicillin (SBPC), cefazolin sodium (CEZ) and cefsulodin sodium (CFS) on the in-vitro electroretinogram (ERG) of the albino rabbit.The b-wave and oscillatory potentials (OPs) were unchanged by 0.1 mM PC-G potassium or PC-G sodium. The OPs were slightly suppressed by 0.3 mM of either drug. While the a- and b-waves were not deteriorated, the OPs were greatly suppressed by 1.0 mM concentration. The effect of PC-G on the ERG was characterized by a selective suppression of the OPs. The b-wave and OPs were not suppressed by 0.03 mM MCIPC. They were slightly suppressed by 0.05 mM MCIPC. The a-wave, b-wave and OPs were not deteriorated by 1.0 mM SBPC. The b-wave and OPs were suppressed by 3.0 mM or 6.0 mM SBPC respectively. These changes appeared to be dose-dependent. Since the b-wave and OPs were concomitantly suppressed by both MCIPC and SBPC, these antibiotics, unlike PC-G, did not selectively suppress the OPs. The b-wave and OPs were unchanged by 0.1 mM CEZ or CFS. The OPs were slightly suppressed by 0.3mM CEZ or CFS. CEZ or CFS of 1.0 mM did not deteriorate the a- and b-waves, but selectively suppressed the OPs. The effects of CEZ and CFS on the ERG were characterized by a selective suppression of the OPs. The above-described changes in the ERG were reversible.  相似文献   
98.
Abnormal development of the brain during fetal life is now thought to contribute to the aetiology of many functional and behavioural disorders that manifest throughout life. Many factors are likely to underlie such abnormal development including genetic makeup and an adverse intrauterine environment. This review will focus on prenatal hypoxic-ischemic injury and inflammatory/infective insults. A range of experimental models have been used to characterise lesions formed in response to these insults and to determine mechanisms of damage resulting from such events. Relatively brief periods of fetal hypoxia result in neuronal death (cerebellum, hippocampus, and cerebral cortex), white matter damage and reduced growth of neural processes. These effects are more profound at mid than late gestation. Chronic mild placental insufficiency can result in fetal growth restriction and deficits in neural connectivity and myelination. Exposure of the preterm fetus to inflammatory agents causes brain damage particularly in the white matter and this is exacerbated by hypoxia. These studies show that the timing, severity and nature of specific insults are critical in determining the pattern of injury and thus the extent to which neurological function will be affected postnatally. Defining the causes, patterns and mechanisms of brain injury is crucial if we are to develop rational neuroprotective strategies to reduce the burden of altered brain growth and poor functional and behavioural outcomes.  相似文献   
99.
The clinical utility of the foveal electroretinogram: A review   总被引:1,自引:0,他引:1  
The historical development of the foveal electroretinogram is reviewed. The factors required to obtain a local cone electroretinogram with a small focal source of illumination against a lighted background are discussed. From these considerations and various studies of macular degeneration, the optimal size of the foveal source is found to be 5° diameter or less. Applications of the foveal electroretinogram in various diseases are summarized. The foveal electroretinogram is abnormal with reduced acuity in age-related macular degeneration, juvenile macular degeneration (Stargardt's disease), retinitis pigmentosa, and diabetic retinopathy. Normal foveal electroretinograms are found in optic atrophy, amblyopia, and optic neuritis. Foveal electroretinograms are normal or abnormal in Best's disease, central serous retinopathy, and several other diseases discussed.  相似文献   
100.
This is a report on the effects of various equally sized copper alloys implanted in the vitreous body of 52 Wistar rats. The main results are as follows: (1) The alloy of 99.9% copper with 0.1% silver (A) destroyed the electroretinogram (ERG) faster than specially purified copper (B). In contrast, copper-zinc alloys (C and D) affected the ERG more slowly than B. This effect is more obvious in alloys containing a large amount of zinc (D). (2) The degree of complication in the anterior segment (iridocyclitis, cornal opacity, hypopyon) and in the vitreous body (intensity and rate of opacity) depend essentially on the type of alloy. The frequency and extent of inflammatory responses decreased in the following order: alloy A, B, C and D.  相似文献   
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