全文获取类型
收费全文 | 1315篇 |
免费 | 52篇 |
国内免费 | 13篇 |
专业分类
耳鼻咽喉 | 252篇 |
儿科学 | 10篇 |
妇产科学 | 3篇 |
基础医学 | 174篇 |
口腔科学 | 4篇 |
临床医学 | 87篇 |
内科学 | 23篇 |
神经病学 | 35篇 |
特种医学 | 94篇 |
外科学 | 17篇 |
综合类 | 118篇 |
预防医学 | 461篇 |
眼科学 | 41篇 |
药学 | 49篇 |
中国医学 | 4篇 |
肿瘤学 | 8篇 |
出版年
2023年 | 14篇 |
2022年 | 24篇 |
2021年 | 22篇 |
2020年 | 13篇 |
2019年 | 15篇 |
2018年 | 28篇 |
2017年 | 24篇 |
2016年 | 25篇 |
2015年 | 41篇 |
2014年 | 72篇 |
2013年 | 109篇 |
2012年 | 81篇 |
2011年 | 83篇 |
2010年 | 56篇 |
2009年 | 66篇 |
2008年 | 53篇 |
2007年 | 61篇 |
2006年 | 61篇 |
2005年 | 66篇 |
2004年 | 44篇 |
2003年 | 32篇 |
2002年 | 21篇 |
2001年 | 26篇 |
2000年 | 33篇 |
1999年 | 31篇 |
1998年 | 25篇 |
1997年 | 28篇 |
1996年 | 18篇 |
1995年 | 18篇 |
1994年 | 21篇 |
1993年 | 16篇 |
1992年 | 15篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 17篇 |
1988年 | 14篇 |
1987年 | 10篇 |
1986年 | 5篇 |
1985年 | 13篇 |
1984年 | 5篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 5篇 |
1976年 | 5篇 |
1974年 | 2篇 |
1973年 | 6篇 |
1972年 | 2篇 |
排序方式: 共有1380条查询结果,搜索用时 0 毫秒
11.
噪声作业人员职业体验研究 总被引:1,自引:1,他引:0
采用华西医科大学劳动卫生教研室研制的系统化职业心理测验(OPT)软件,对四川第一棉纺织厂织布车间噪声(101.2dB(A))作业女工98人职业体验进行考察。以OPT常模女性工人组为对照(年龄、工龄、文化程度等与观察组同),按标准化OPT方法实施测验和统计分析。结果提示噪声作业女工职业体验欠佳,职业满意度、工作生活质量均低于常模。 相似文献
12.
Sofía A. Sanz Ana M. García Amando García 《International archives of occupational and environmental health》1993,65(3):205-207
Summary Noise levels around educational centres can negatively affect the performance of both teachers and pupils. Two public schools in Valencia, Spain, were selected for study. One of these schools was exposed to excessively high road traffic noise levels while the other was located in a relatively quiet area. The socioeconomic level of those attending the schools was very similar. A set of external and internal noise measurements were carried out, along with two different attention tests among the children. Test results were consistently better (both for tests and for children from different classrooms in each school) in the quiet school. Exposure to high traffic noise levels in the noisy school over the whole school year is a plausible determinant of these results. 相似文献
13.
T. Takaki 《Medical & biological engineering & computing》1988,26(4):397-403
The paper considers the limiting factors in EEG enhancement in the presence of electrosurgery interference and presents a
design for a useful fibre-optic EEG monitoring instrument which is free from such problems as electrical shock (micro and
macroshock), patient burns and susceptibility to electrosurgery interference associated with conventional EEG monitors. 相似文献
14.
A new algorithmic-based digital filter processing system for real-time continuous blood pressure (BP) measurement and analysis in freely-moving conscious rats has been developed. Real-time recognition of BP waveforms, real-time noise rejection and determination of representative waveform indexes (WIs) at indicated time points using digital filters and Smirnov's rejection test were realized with this system. Digital filters were applied for two different purposes: waveform segmentation and smoothing the calculations of representative WIs. Smirnov's rejection test was used for real-time noise rejection and yielded an accurate rejection rate of 99.99%. The result was that the digital filter processing and Smirnov's rejection test realized accurate real-time BP measurement and analysis in freely-moving conscious rats using a personal computer. 相似文献
15.
Helmut Seidel Ralph Blüthner Janos Martin Gerhard Menzel Rudolf Panuska Peter Ullsperger 《European journal of applied physiology》1992,65(4):376-382
Summary Auditory event-related brain potentials (ERP) in response to two different tone stimuli (1.1 kHz or 1 kHz, 80 dB, 50 ms; given by headphones at a regular interstimulus interval of 5 s with a probability distribution of 70:30) were recorded from 12 healthy male subjects (Ss) during four different conditions with two repetitions: A - 60 dBA white noise (wN), no wholebody vibration (WBV); B - 60 dBA wN plus sinusoidal WBV in the az-direction with a frequency of 2.01 Hz and acceleration of 2 m ·s–2 root mean square; C - 80 dBA wN, no WBV; D - 80 dBA wN plus WBV. Each condition consisted of two runs of about 11 min interrupted by a break of 4 min. During the break with continuing exposure, but without auditory stimuli, Ss judged the difficulty of the tone-detection task and intensity of noise by means of cross-modality matching (CMM). Vibration-synchronous activity in the electrocardiogram was eliminated by a subtraction-technique. Noise caused an attenuation of the N1 and P2 amplitudes and prolongation of P3 latencies. The WBV did not cause systematic ERP effects. Condition B was associated with higher N1 and smaller P3 amplitudes. The factor condition had a significant effect on the peak latencies of P3 to target stimuli and the task difficulty judged by CMM. Both effects exhibited significant linear increases in the sequence of conditions A, B, C, D. For the evaluation of exposure conditions at work, it can be suggested that noise has a strong systematic effect which can be enhanced by WBV. The P3 latency is considered as an advantageous measure for the detection of objective effects of physical environmental factors, correlating with relevant subjective responses. 相似文献
16.
Summary This study was undertaken to investigate the dose-response relationship between the biological effect and noise exposure, and to consider the mechanism of the appearance of noise effects. Rats were exposed to noise at intensities of 60 dB (A), 80 dB (A) and 100 dB (A) for 240 min and examined for the change of activities of dopamine--hydroxylase (DBH) in serum and adrenal glands. Plasma cyclic adenosine 3,5-monophosphate (c-AMP) levels were also measured. Some rats were given 6-hydroxydopamine (6-OHDA) as a chemical sympathectomyzing agent 20 h before noise exposure in order to consider the mechanism of the appearance of noise effects. By noise exposure, serum DBH activity was significantly (P<0.01) increased at each intensity compared with the control group, but there were no remarkable changes in adrenal DBH activity. Plasma c-AMP level was also significantly elevated in response to the noise stress. When the rats, which had been pretreated with 6-OHDA, were exposed to noise with an intensity of 100 dB (A), the response of serum DBH activity was no longer observed. Therefore it is suggested that the effect due to noise exposure appears through the post-ganglionic sympathetic nerve fiber. 相似文献
17.
M. V. Thomas 《Medical & biological engineering & computing》1977,15(4):450-454
A circuit is described which allows the input capacitance of an f.e.t. input integrated circuit to be used both as the feedback capacitance to neutralise the total input capacitance and to inject current pulses into the input. Compared with the conventional method of adding discrete capacitors to perform these functions, this design results in a lower total capacitance at the input, which reduces the high-frequency noise generated by the amplifier and facilitates the achievement of a low effective capacitance. A modified version having an ultralow (0·1pA) input current, for use with ion-sensitive microelectrodes, is also described. 相似文献
18.
Hiroyuki Nakamura Takashi Moroji Hirofumi Nagase Takao Okazawa Akira Okada 《European journal of applied physiology》1994,68(1):62-67
To clarify the role of vasoactive intestinal polypeptide (VIP) and somatostatin, somatropin-release inhibiting factor, (SRIF) neurons in the response to organisms to noise or whole-body vibration stress, VIP and SRIF-like immunoreactivity were determined in various regions of the rat brain following exposure for 90 min to noise (broad band, 102 dB) or whole-body vibration (20 Hz, 4.0 g). Both noise and whole-body vibration significantly increased VIP-like immunoreactivity in the amygdala. A significant reduction of VIP like immunoreactivity in the hippocampus was induced only by whole-body vibration. On the other hand SRIF-like immunoreactivity was decreased significantly in the hypothalamus and increased significantly in the amygdala by noise and whole-body vibration, respectively. The present findings would seem to indicate that the amygdalofugal VIP neural system is involved in regulating hypothalamic and pituitary hormone secretions in non-specific reactions to stress. Responses of hippocampal VIP and the amygdalofugal SRIF to whole-body vibration stress are assumed to be activated as specific reactions to the stress. 相似文献
19.
Summary Ionic channel properties of acetylcholine receptors located in, in the vicinity of, or far away from a frog neuromuscular
junction were investigated by noise analysis of drug induced current fluctuations. For drugs applied to the junction, in certain
cases two Lorentzian curves were necessary to describe the data. It is postulated that the reason for this observation is
that a contribution from perijunctional receptors was being observed. The conductance of a single channel in the junction
was independent of the nature of the agonist and had an average value of 17.9 pS (temperature range 8–25°C, solution buffered
with Tris). After denervation for 21 days the conductance γ was 7.5 pS at extrajunctional locations. In the close neighbourhood
of the junction (perijunctional receptors) values were found between 4 and 19 pS.
The mean value of the open channel life-time τ in the endplate exposed to acetylcholine was 2.4 ms at 8–11°C. This value was
0.90 ms with carbachol, 0.50 ms with succinylcholine, 0.28 ms with decamethonium and 0.45 ms with nicotine. The receptors
outside the endplate exhibited τ-values which at a given temperature were 2–3 times larger than those at the endplate. Raising
the temperature to 23°C reduced all τ-values by factors of 2–3. It is concluded that at least two types of ACh-receptors with
different properties exist in the muscle membrane, possibly produced by ACh-receptive units in different states of aggregation.
This work was supported by the Deutsche Forschungsgemeinschaft, SFB 38, Project N 相似文献
20.
D. T. Godin P. A. Parker R. N. Scott 《Medical & biological engineering & computing》1991,29(6):585-590
Bioelectric events measured with surface electrodes are subject to noise components which may be significant in comparison
with low-level biological signals such as evoked neuroelectric potentials, and myoelectric potentials. In an effort to better
understand noise arising from these electrodes, electrode and measurement system noise is modelled. The effect of electrode
surface area on electrode impedance and noise is studied using circular stainless-steel electrodes of varying diameters. The
main contributions of the work are the development of a model for stainless-steel electrode noise as a function of electrode
area, and demonstrating that, for the band-width of interest to evoked neuroelectric and myoelectric signals (8–10 000 Hz),
the primary noise components are thermal and amplifier current generated. The magnitudes of both of these depend on the electrode
impedance magnitude. Electrode impedance is shown to be a power function of both electrode diameter and frequency, consistent
with a capacitive electrode model. 相似文献