全文获取类型
收费全文 | 12377篇 |
免费 | 676篇 |
国内免费 | 195篇 |
专业分类
耳鼻咽喉 | 115篇 |
儿科学 | 695篇 |
妇产科学 | 116篇 |
基础医学 | 619篇 |
口腔科学 | 21篇 |
临床医学 | 3027篇 |
内科学 | 2190篇 |
皮肤病学 | 41篇 |
神经病学 | 198篇 |
特种医学 | 355篇 |
外国民族医学 | 3篇 |
外科学 | 1562篇 |
综合类 | 2371篇 |
预防医学 | 787篇 |
眼科学 | 13篇 |
药学 | 892篇 |
12篇 | |
中国医学 | 151篇 |
肿瘤学 | 80篇 |
出版年
2024年 | 19篇 |
2023年 | 187篇 |
2022年 | 304篇 |
2021年 | 490篇 |
2020年 | 472篇 |
2019年 | 369篇 |
2018年 | 372篇 |
2017年 | 428篇 |
2016年 | 474篇 |
2015年 | 401篇 |
2014年 | 889篇 |
2013年 | 801篇 |
2012年 | 790篇 |
2011年 | 858篇 |
2010年 | 699篇 |
2009年 | 641篇 |
2008年 | 583篇 |
2007年 | 635篇 |
2006年 | 554篇 |
2005年 | 506篇 |
2004年 | 377篇 |
2003年 | 301篇 |
2002年 | 209篇 |
2001年 | 194篇 |
2000年 | 160篇 |
1999年 | 161篇 |
1998年 | 133篇 |
1997年 | 120篇 |
1996年 | 137篇 |
1995年 | 121篇 |
1994年 | 96篇 |
1993年 | 74篇 |
1992年 | 87篇 |
1991年 | 62篇 |
1990年 | 78篇 |
1989年 | 76篇 |
1988年 | 47篇 |
1987年 | 57篇 |
1986年 | 45篇 |
1985年 | 48篇 |
1984年 | 43篇 |
1983年 | 25篇 |
1982年 | 23篇 |
1981年 | 19篇 |
1980年 | 29篇 |
1979年 | 13篇 |
1978年 | 12篇 |
1977年 | 9篇 |
1975年 | 4篇 |
1971年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 593 毫秒
91.
K. Yamakoshi A. Kawarada A. Kamiya H. Shimazu H. Ito 《Medical & biological engineering & computing》1985,23(5):459-465
A new portable instrument equipped with a microprocessor was designed for the long-term ambulatory monitoring of indirect
arterial pressure in the human finger at desired intervals using a volume-oscillometric technique. All the necessary procedures
such as (1) programmed control of cuff pressure, (2) detection of the systolic end-point and the point of maximum amplitude
of arterial volume pulsations, (3) reading of the cuff pressures corresponding to these two points, (4) its processing and
(5) recording of the systolic and mean pressure together with heart rate on a digital memory integrated circuit were performed
automatically. After the monitoring, the data were reproduced and analysed by a conventional personal computer. Simultaneous
comparison of the data with direct measurement, operation and evaluation of this instrument, and ambulatory monitoring were
carried out. With this instrument noninvasive and accurate monitoring of arterial pressure could be made in unrestricted subjects
during daily activities. 相似文献
92.
CROOKE P. S.; HEAD J. D.; MARINI J. J.; HOTCHKISS J. R. 《Mathematical medicine and biology》1998,15(4):321-337
A general mathematical model for the dynamic behaviour of asingle-compartment respiratory system in response to an arbitraryapplied inspiratory airway pressure and arbitrary respiratorymuscle activity is investigated. The model is used to computeexplicit expressions for ventilation and pressure variablesof clinical interest for clinician-selected and impedance-determinedinputs. The outcome variables include tidal volume, end-expiratorypressure, minute ventilation, mean alveolar pressure, averagepleural pressure, as well as the work performed by the ventilatorand the respiratory muscles. It is also demonstrated that undersuitable conditions, there is a flow reversal that can occurduring inspiration. 相似文献
93.
由于人体组织中存在血液对流传热和代谢产热,当皮肤表面绝热后,皮肤表面的温度将上升,体表温升值是人体组织中血液灌注率和动脉血温度的函数,根据实际测量的体表温升与时间的关系就可以测出活体组织的血液灌注率和动脉血温度。根据一维Pennes生物传热方程,推导出了体表绝热后人体组织中及皮肤表面温度分布的解析解,并对人体组织中的血液灌注率及动脉血温度进行了实验测量。由于测量过程中利用的只是皮肤表面的温度信息,无须引入外加热源,对人体组织完全不会造成损伤,亦避免了干扰人体组织的正常生理状态,整个测量系统也比较简单。 相似文献
94.
Continuous estimation of systolic blood pressure using the pulse arrival time and intermittent calibration 总被引:8,自引:0,他引:8
Chen W Kobayashi T Ichikawa S Takeuchi Y Togawa T 《Medical & biological engineering & computing》2000,38(5):569-574
A continuous noninvasive method of systolic blood pressure estimation is described. Systolic blood pressure is estimated by
combining two separately obtained components: a higher frequency component obtained by extracting a specific frequency band
of pulse arrival time and a lower frequency component obtained from the intermittently acquired systolic blood pressure measurements
with an auscultatory or oscillometric system. The pulse arrival time was determined by the time interval from QRS apex in
electrocardiogram to the onset of photoplethysmogram in a fingertip beat-by-beat via an oximetric sensor. The method was examined
in 20 patients during cardiovascular surgery. The estimated values of systolic blood pressure were compared with those measured
invasively using a radial arterial catheter. The results showed that the correlation coefficients between estimated values
and invasively obtained systolic blood pressure reached 0.97±0.02 (mean±SD), and the error remained within ±10% in 97.8% of
the monitoring period. By using a system with automatic cuff inflation and deflation to acquire intermittent systolic blood
pressure values, this method can be applicable for the continuous noninvasive monitoring of systolic blood pressure. 相似文献
95.
Clinical efficacy of reduction in house-dust mite exposure in specially designed, mechanically ventilated "healthy" homes 总被引:2,自引:2,他引:2
In temperate climates, energy-conserving measures may increase indoor humidity, enhancing house-dust mite (HDM) growth. Movement of families to "healthy" homes with mechanical ventilation systems reduced HDM exposure. The effect on asthma control of moving to the "healthy" homes was studied in 14 asthmatic patients allergic to HDM. Base-line evaluations of lung function, asthma symptoms, and medication requirements were made before moving and again after 5 and 15 months' residence. A control group of 11 mite-sensitive asthmatic patients who did not move were examined contemporaneously with the study group at base line and at the first follow-up investigation. After 5 months, the residents of the "healthy" homes improved in forced expiratory volume in 1 s (FEV1 ), medicine score, and serum IgE. These changes were significantly different from control group measurements. After 15 months, statistically significant improvements from base line were found in FEV1 , average daily peak expiratory flow values, medicine score, symptom score, and serum IgE. Insignificant trends toward improvement were seen in provocation concentration of histamine and blood eosinophils. A significant relation was found between reduction in medicine score and fall in HDM exposure. The present study shows that a specific HDM-avoidance procedure can result in an overall, clinical improvement in HDM-sensitive asthmatic patients. 相似文献
96.
Inverted, cataleptic goldfish showed an increase in ventilation rate over a 20 min period. The time-dependent increase in respiratory movement was initially suppressed when a 10 sec light or a 0.1 sec shock was presented at 1.5 min intervals. Contingent presentation of the light and shock, in a classical conditioning paradigm, resulted in reduced ventilation rates during the session. Physiological changes accompanying conditioning may thus alter the cataleptic state. 相似文献
97.
Rieko Nishimura Takahiro Hasebe Shigeru Imoto K. Mukai 《Virchows Archiv : an international journal of pathology》1998,432(1):89-93
A malignant phyllodes tumour with a noninvasive ductal carcinoma component is reported. The patient was an 80-year-old Japanese
woman with a breast tumour detected by routine physical examination. A simple mastectomy was performed. The excised tumour
was 10.5×9.4×5.4 cm in size and bulged into the skin with ulceration. The macroscopic appearance was that of a phyllodes tumour.
Histologically the tumour consisted mainly of stromal components with a leaf-like structure lined by atypical ductal epithelium.
The epithelial component showed gradual evolution to intraductal papillary carcinoma in a few areas. The stromal component
was composed mainly of fibrosarcoma with areas of osteosarcoma and rhabdomyosarcoma. Neither stromal invasion of intraductal
carcinoma nor transition between the stromal and epithelial elements was seen. Three months after the operation, death occurred,
with multiple pulmonary and subcutaneous metastases. This case probably represents malignant change in both the stromal and
the epithelial components of a phyllodes tumour. Since the two elements were independent, the possibility that a phyllodes
tumour may be one of the origins of true carcinosarcoma is raised.
Received: 11 March 1997 / Accepted: 5 May 1997 相似文献
98.
Aims: We examined whether or not streptozotocin (STZ)‐induced diabetic rats, which have a lower heart rate (HR, beats min?1) than control rats, could maintain hypoxic ventilatory response. Methods: Twenty‐six Wistar rats, which had been injected with STZ (60 mg kg?1, EXP) or vehicle (0.1 m citrate buffer, CONT) intraperitoneally at 9 weeks of age, had their cardiorespiratory responses to normoxia and 12%O2 examined after 5 weeks. Results: Compared with CONT rats, EXP rats had a higher blood glucose [24 ± 3 vs. 5 ± 1 (mean ± SD) mmol L?1], a lower body weight (320 ± 23 vs. 432 ± 24 g), lower HR (303 ± 49 vs. 380 ± 44 in normoxia, and 343 ± 56 vs. 443 ± 60 in hypoxia) and a lower mean arterial blood pressure (MAP) (89 ± 6 vs. 102 ± 10 mmHg in hypoxia). In contrast, both groups had similar values in ventilation (), –metabolic rate (MR) ratio and arterial blood gases (ABGs). In EXP rats, with an acute insulin supplement (i.v., 0.75 U h?1 for 1.5–2 h), not only blood glucose, but also HR, and MAP were normalized as those obtained in CONT rats, and in hypoxia further increased without affecting –MR ratio and ABGs. Such acute cardiorespiratory stimulating effects of insulin could not be obtained in non‐diabetic rats (n = 7, 355 ± 24 g), in which euglycaemia (mean 6.4 mmol L?1) was maintained during the measurements. Conclusions: Our results suggest that, in STZ‐induced diabetic rats: (1) ventilation is hardly suppressed by hyperglycaemia, (2) cardiorespiratory responses can be acutely stimulated by short insulin injection, and (3) the effects, including those through acute blood glucose normalization, are possibly specific for the diabetic impairments. 相似文献
99.
D. J. PATERSON 《Acta physiologica (Oxford, England)》1996,156(3):287-294
In exercise, potassium (K+) is released from contracting muscle predominately through K+ channels associated with the repolarization phase of the action potential. Increases in extracellular K+ are directly related to increases in metabolic rate and may reach concentrations as high as 8–9 mm in the arterial blood during exhaustive work. Exercise-induced hyperkalaemia has been implicated in several physiological processes, in particular skeletal muscle fatigue, hyperaemia, pressor reflex, arterial chemosensitivity and myocardial stability. There is no direct evidence to show that hyperkalaemia causes muscle fatigue, although raised extracellular [K+] may contribute to fatigue during prolonged tetani by depressing the propagation of the action potential down the t-tubule system, thus impairing the release of Ca2+ from the sarcoplasmic reticulum. The vasodilating properties of K+ may transiently contribute to the early phase of exercise hyperaemia and interact synergistically with other vasoactive substances to cause relaxation by hyperpolarizing K+ channels in vascular smooth muscle. Hyperkalaemia has been implicated in the regulation of arterial blood pressure through activation of the muscle afferent reflex where potassium-depolarized C fibres may contribute to a reflex increase in arterial blood pressure. K+ can also increase ventilation and the sensitivity of the ventilatory response to hypoxia through direct excitation of the arterial chemoreceptors. Finally, to maintain myocardial electrical stability in exercise, there is a beneficial interaction between raised K+ and catecholamines on the heart, so that when they combine, each offsets the other's deleterious effects. 相似文献
100.
To elevate effects of carbon dioxide (CO2) retention by way of an increased respiratory load during submaximal exercise (150 W), the concentration changes of oxy‐ (ΔHbO2) and deoxy‐haemoglobin (ΔHb) of active muscles and the brain were determined by near‐infrared spectroscopy (NIRS) in eight healthy males. During exercise, pulmonary ventilation increased to 33 (28–40) L min–1 (median with range) with no effect of a moderate breathing resistance (reduction of the pneumotach diameter from 30 to 14 and 10 mm). The end‐tidal CO2 pressure (PETCO 2) increased from 45 (42–48) to 48 (46–58) mmHg with a reduction of only 1% in the arterial haemoglobin O2 saturation (SaO 2). During control exercise (normal breathing resistance), muscle and brain ΔHbO2 were not different from the resting levels, and only the leg muscle ΔHb increased (4 (–2–10) μM , P < 0.05). Moderate resistive breathing increased ΔHbO2 of the intercostal and vastus lateralis muscles to 6 ± (–5–14) and 1 (–7–9) μM (P < 0.05), respectively, while muscle ΔHb was not affected. Cerebral ΔHbO2 and ΔHb became elevated to 6 (1–15) and 1 (–1–6) μM by resistive breathing (P < 0.05). Resistive breathing caused an increased concentration of oxygenated haemoglobin in active muscles and in the brain. The results indicate that CO2 influences blood flow to active skeletal muscle although its effect appears to be smaller than for the brain. 相似文献