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61.
Müller K Schmitz F Schnitzler A Freund HJ Aschersleben G Prinz W 《Journal of cognitive neuroscience》2000,12(4):546-555
Sensorimotor synchronization tasks, in which subjects have to tap their finger in synchrony with an isochronous auditory click, typically reveal a synchronization error with the tap preceding the click by about 20 to 50 msec. Although extensive behavioral studies and a number of different explanatory accounts have located the cause of this so-called "negative asynchrony" on different levels of processing, the underlying mechanisms are still not completely understood. Almost nothing is known about the central processes, in particular, which sensory or motor events are synchronized by subjects. The present study examined central-level processing in synchronization tasks with magnetoencephalography (MEG). Eight subjects synchronized taps with their right index finger to an isochronous binaural pacing signal presented at an interstimulus interval of 800 msec. To gain information on central temporal coupling between "tap" and "click," evoked responses were averaged time-locked to the auditory signal and the tap onset. Tap-related responses could be explained with a three dipole model: One source, peaking at approximately 77 msec before tap onset, was localized in contralateral primary motor cortex (MI); the two other sources, peaking approximately at tap onset and 75 msec after tap onset, in contralateral primary somatosensory cortex (SI). Temporal coupling of these sources was compared in relation to different trigger points. The second SI source was equally well time-locked to the tap and to the auditory click. Furthermore, analysis of the time locking of this source activity as a function of the temporal order of tap and click showed that the second event - irrespective whether tap or click - was decisive in triggering the second SI source. This suggests that subjects use mainly sensory feedback in judging and evaluating whether they are "keeping time." 相似文献
62.
The execution of meaningless movement sequences was studied in 12 patients with lesions of the parietal cortex in comparison to the performance of age- and sex-matched controls. Five sequences of increasing complexity had to be performed by imitation and after verbal instruction. The performance errors were qualitatively scored by means of four error categories (temporal or spatial error, addition or omission of movement components). This study examined whether the error scores depended on instruction modality, movement complexity or lesion side. Patients with left parietal lesions produced more errors than those with right parietal lesions and control subjects. While additions or omissions of movement components occurred almost equally in all groups, temporal and spatial errors were more frequent in patients with left parietal lesions only. In addition, only the latter group showed a significant increase of error rates with increasing movement complexity. There were no significant differences between the contra- and ipsilesional hand in any group. These results demonstrate that lesions in the left parietal lobe lead to a disturbed spatio-temporal organisation of movement that becomes increasingly prominent for more complex movements. 相似文献
63.
M Cole L Parker AW Craft S Bell G Dale AC McGill JA Seviour J Smith 《Archives of disease in childhood》1993,68(3):376-378
The relationship between homovanillic acid (HVA), vanillylmandelic acid (VMA), and creatinine in the urine of 6 month old babies has been studied and reference ranges in the form of centiles constructed for HVA and VMA against creatinine. Over 10,000 urine samples were collected from babies in four health districts in the north of England. HVA and VMA concentration, either independently or when divided by creatinine concentration, were dependent upon the absolute concentration of creatinine in the sample. After adjustment for creatinine significant differences in the mean concentration of HVA were found between sexes. No such differences were found for VMA. HVA and VMA were also found to be age dependent. Centiles were constructed using a procedure which makes no distributional assumptions about the data. The net effect of utilising these centiles was to increase the predictive value of a positive screening test from 20% to 40% without any increase in the false negative rate. 相似文献
64.
The amplitude of the acoustic startle response (ASR) in rats is increased after administration of footshocks, a phenomenon termed sensitization. The neural circuitry underlying this kind of modulation of the ASR is only partly understood. It has been shown that the central nucleus of the amygdala (cA) and its efferent pathway to the caudal pontine reticular nucleus (PnC), an essential part of the primary startle circuit, is important for the sensitization of the ASR [23]. It was unclear, however, whether the amygdaloreticular pathway directly transfers the effects of footshocks onto the PnC, or whether there exists a relay nucleus within this pathway. The present study tested the hypothesis that the midbrain central gray (CG) is important for the sensitization of the ASR. Neuroanatomical tracing experiments indicate that a descending projection from the medial part of the cA might form synapses in the region of the midbrain CG, where a descending projection to the PnC takes its origin. We lesioned the dorsal and lateral part of the CG with the neurotoxin quinolinic acid and measured the effects of this lesion on the sensitization of the ASR by footshocks. Lesions confined to the dorsal and lateral parts of the CG totally blocked the sensitization of the ASR, without affecting the ASR amplitude in the absence of sensitizing stimuli. These findings suggest a crucial role of the CG for the sensitization of the ASR. The present data are reconciled with other findings from our laboratory and from the literature and we discuss possible mechanisms underlying the mediation of the sensitization of the ASR in rats. 相似文献
65.
C H Grupper B Berretti L Schnitzler D Bensoussan 《Annales de dermatologie et de vénéréologie》1978,105(3):291-298
A group of 18 patients with mycosis fungoides (M.F.) was treated by PUVAtherapy. According to VanScott classification, they have been set in:--5 parapsoriasis in large plaques = 5 stages I;--6 stages II;--3 stages III;--2 stages IV;--1Sézary syndrom.--1 erythrodermia. There was complete clearing of 12 patients (66 p. 100); 2 patients (11 p. 100) improved cutaneous lesions without a complete clearing, and there was no response to treatment for 3 patients (22 p. 100) (1 with erythrodermia, 1 with Sézary syndrom and 1 stage IV, and 1 forsaking). The method applied here was different in several points: orally administered methoxalen were given according to the body area (mg/m2) and some of the patients had twice a day puvatherapy. Puvatherapy seems to be the least dangerous and most effective treatment for the patients in the early stages of mycosis fongoides (I, II) and nitrogen mustard, electron therapy, corticoids and even mono- or polychimiotherapy could be associated to puvatherapy, if necessary, for the stages III and IV. 相似文献
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70.
GS Chopra PK Gupta AC Anand PP Varma V Nair Ramji Rai 《Medical Journal Armed Forces India》2005,61(3):234-237