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排序方式: 共有347条查询结果,搜索用时 15 毫秒
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Using data from the National Health and Nutrition Examination Survey (NHANES II) 1976-1980, we demonstrate how cross-sectional total serum cholesterol surveillance data can be used by an individual to assess current and future personal cholesterol risk status. We propose statistical models, based on a person's current measured cholesterol level and the relationship between cross-sectional age and cholesterol percentile estimates, that will allow prediction of future cholesterol levels or the age at which specified cholesterol risk levels will be reached if no cholesterol-altering intervention is taken. These models incorporate the observed variation in the NHANES II data and expected intraperson biological variation and intralaboratory analytical variation. We illustrate the adequacy of the models using data from the longitudinal Framingham Study. 相似文献
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Petit J Klam F Grantyn A Berthoz A 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1999,125(3):287-301
Pontine omnipause neurons (OPNs) have so far been considered as forming a homogeneous group of neurons whose tonic firing
stops during the duration of saccades, when the head is immobilized. In cats, they pause for the total duration of gaze shifts,
when the head is free to move. In the present study, carried out on alert cats with fixed heads, we present observations made
during self-initiated saccades and during tracking of a moving target which show that the OPN population is not homogeneous.
Of the 76 OPNs we identified, 39 were found to have characteristics similar to those of previously described neurons, ”saccade”
(S-) OPNs: (1) the durations of their pauses were significantly correlated with the durations of saccades; (2) the discharge
ceased shortly before saccade onset and resumed before saccade end; (3) visual responses to target motion were excitatory;
and (4) during tracking, S-OPNs interrupted the discharge for the duration of saccades and resumed firing during perisaccadic
”drifts”. However, the characteristics of 37 neurons (”complex” (C-) OPNs) were different: (1) the pause duration was not
correlated with the duration of self-initiated saccades; (2) time lead of pause onsets relative to saccades was, on average,
longer than in the group of S-OPNs, and firing resumed after the saccade end; (3) visual target motion suppressed tonic discharges;
and (4) during tracking, firing was interrupted for the total duration of gaze shifts, including not only saccades but also
perisaccadic ”drifts”. We conclude that cat OPNs can be subdivided into two main groups. The first comprises neurons whose
firing patterns are compatible with gating individual saccades (”saccade” OPNs). The second group consists of ”complex” OPNs
whose firing characteristics are appropriate to gate total gaze displacements rather than individual saccades. The function
of these neurons may be to disinhibit pontobulbar circuits participating in the generation of saccade sequences and associated
perisaccadic drifts.
Received: 20 January 1998 / Accepted: 22 October 1998 相似文献
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纪震 《中国医疗器械杂志》1999,23(5):252-257
提出基于自适应方向滤波方法来提取左心室轮廓。在噪声的干扰下,引入经平滑处理的方向滤波能够得到精确的边缘,所获得的边缘方向矢量能够在边缘跟踪时对边缘走向预测,同时对参数进行自适应地调整。通过尽量少的人机交互,算法能够自动提取出左心室的轮廓。实验证明该算法增加了边缘提取的精度和一致性,同时显著地降低了计算复杂度。 相似文献
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A large body of research has demonstrated that affective disorders are characterized by attentional biases for emotional stimuli. However, this research relies heavily on manual reaction time (RT) measures that cannot fully delineate the time course and components of attentional bias. Eye tracking technology, which allows relatively direct and continuous measurement of overt visual attention, may provide an important supplement to RT measures. This article reviews eye tracking research on anxiety and depression, evaluating the experimental paradigms and eye movement indicators used to study attentional biases. Also included is a meta-analysis of extant eye tracking research (33 experiments; N = 1579) on both anxiety and depression. Relative to controls, anxious individuals showed increased vigilance for threat during free viewing and visual search, and showed difficulty disengaging from threat in visual search tasks, but not during free viewing. In contrast, depressed individuals were not characterized by vigilance for threat during free viewing, but were characterized by reduced orienting to positive stimuli, as well as reduced maintenance of gaze on positive stimuli and increased maintenance of gaze on dysphoric stimuli. Implications of these findings for theoretical accounts of attentional bias in anxiety and depression are discussed, and avenues for future research using eye-tracking technology are outlined. 相似文献
10.
《Clinical and experimental hypertension (New York, N.Y. : 1993)》2013,35(4-5):539-545
We compared blood pressure (BP) values, measured at a five year interval, in 2 777 boys and girls aged 4-18 years. BP values were converted into height and sex adjusted standard deviation unit scores. Correlation coefficients were significant but low for systolic BP score: 0.19 in boys and 0.15 in girls, and were even lower for diastolic BP score. These correlations are weaker than those observed for overall BP values (boys: 0.33, girls: 0.23), weight (0.82, 0.75) and height (0.87, 0.80). The probability of remaining in a high percentile (> 95th) is low since only 14p. cent of boys and 8p. cent of girls whose first systolic BP value was greater than the 95th percentile were still in this range five years later. Probability was still weaker for diastolic BP. BP tracking exists but would appear to be weak to permit early detection of future hypertensives, and does not justify preventive measures other than advice on diet and way of life. 相似文献