首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6846篇
  免费   429篇
  国内免费   163篇
耳鼻咽喉   16篇
儿科学   200篇
妇产科学   46篇
基础医学   579篇
口腔科学   117篇
临床医学   827篇
内科学   1579篇
皮肤病学   47篇
神经病学   330篇
特种医学   234篇
外科学   509篇
综合类   719篇
现状与发展   1篇
预防医学   1145篇
眼科学   31篇
药学   608篇
  4篇
中国医学   358篇
肿瘤学   88篇
  2024年   16篇
  2023年   119篇
  2022年   238篇
  2021年   332篇
  2020年   278篇
  2019年   246篇
  2018年   266篇
  2017年   260篇
  2016年   223篇
  2015年   211篇
  2014年   431篇
  2013年   556篇
  2012年   337篇
  2011年   386篇
  2010年   273篇
  2009年   296篇
  2008年   326篇
  2007年   324篇
  2006年   294篇
  2005年   231篇
  2004年   187篇
  2003年   166篇
  2002年   139篇
  2001年   119篇
  2000年   89篇
  1999年   82篇
  1998年   56篇
  1997年   85篇
  1996年   83篇
  1995年   76篇
  1994年   76篇
  1993年   54篇
  1992年   58篇
  1991年   54篇
  1990年   51篇
  1989年   36篇
  1988年   40篇
  1987年   35篇
  1986年   29篇
  1985年   42篇
  1984年   37篇
  1983年   23篇
  1982年   36篇
  1981年   18篇
  1980年   25篇
  1979年   17篇
  1978年   17篇
  1977年   18篇
  1976年   9篇
  1971年   9篇
排序方式: 共有7438条查询结果,搜索用时 15 毫秒
61.
  1. Download : Download high-res image (158KB)
  2. Download : Download full-size image
  相似文献   
62.
The diffusing capacity of the lung for carbon monoxide (DLCO) decreases to below the pre-exercise value in the hours following a bout of intense exercise. Two mechanisms have been proposed: (1) development of pulmonary oedema and (2) redistribution of central blood volume to peripheral muscles causing a reduction in pulmonary capillary blood volume (Vc). In the present study DLCO, Vc and the membrane diffusing capacity (Dm) were measured in nine healthy females using a rebreathing method, in contrast to the single breath technique employed in previous studies. DLCO, Vc and Dm were measured before and at 1, 2, 3, 16 and 24 h following maximal treadmill exercise. Compared with pre-exercise values, DLCO was depressed by up to 8.9 (3.0)% (P<0.05) for the first 3 h following exercise, but had returned to pre-exercise values by 16 h post-exercise. Vc fell by 21.2 (4.1)% (P<0.05) at 3 h post-exercise, but at the same time Dm increased by 14.7 (9.1)%. It was concluded that: (1) the increase in Dm made it unlikely that the fall in DLCO was due to interstitial oedema and injury to the blood gas barrier; (2) on the other hand, the reduction in DLCO following exercise was consistent with a redistribution of blood away from the lungs; and (3) the trend for Dm and Vc to reciprocate one another indicates a situation in which a fall in Vc nevertheless promotes gas transfer at the respiratory membrane. It is suggested that this effect is brought about by the reorientation of red blood cells within the pulmonary capillaries following exercise.  相似文献   
63.
We measured the aerobic capacity, sweat rate and fluid intake of trained athletes during outdoor exercise and examined the relationship between aerobic capacity and thermoregulatory responses at high ambient temperatures. The maximal aerobic capacity ( ) of the subjects, nine male baseball players of college age, was determined by maximal exercise tests on a cycle ergometer. The subjects practised baseball regularly without drinking fluids from 1330 to 1530 hours. After 30 min rest, they played a baseball game with free access to a sports drink at 15°C from 1600 to 1830 hours. At a mean ambient temperature of 36.7 (SEM 0.2)°C, the mean percentage of body mass loss (m b) and increase of oral temperature (T o) from 1330 to 1530 hours was 3.47 (SEM 0.12)% and 0.81 (SEM 0.14)°C, respectively. The sweat loss from 1330 to 1830 hours was 56.53 (SEM 1.56)ml · kg–1 of body mass (M b) while the mean fluid consumption was 44.78 (SEM 2.39)ml · kg–1 ofm b, with recovery of 76.08 (SEM 2.81)% of sweat loss. The was significantly inversely correlated withm b, fluid intake and rehydration amount, but showed no correlation withT o. These results would suggest that at a given exercise intensity in subjects with a higher aerobic capacity body temperature is maintained with a lower sweating rate than that in subjects with a lower aerobic capacity.  相似文献   
64.
Summary 1. The effect of streptozotocin (STZ) induced diabetes on rat urinary bladder function was investigated by means of in vivo cystometry and in vitro recording of bladder strips contractility. A group of sucrose-fed animals was included to determine to what extent the STZ-induced changes were ascribable to the increased diuresis. 2. After 7–9 weeks from STZ injection there was a marked increase in weight of bladder and ureters. Cystometry revealed a marked increase in bladder capacity (volume threshold) although pressure threshold and amplitude of micturition contraction were unaffected. Sucrose-fed animals, having normal blood glucose levels but a similar increase in urine production exhibited cystometric changes identical to those of STZ animals. 3. In vitro experiments indicated that the response to field stimulation (0.1–20 Hz) is reduced in STZ-pretreated but increased in sucrose-fed animals, as compared to controls. 4. The content of urinary bladder and ureters in sensory neuropeptides (substance-P, neurokinin-A and calcitonin-gene related peptide-like immunoreactivity) was increased by STZ diabetes when values were corrected for the increased weight of these organs. 5. The capsaicin-induced contraction of the rat isolated bladder strips, presumably caused by neuropeptides released from intramural sensory nerves, is unaffected by STZ diabetes. 6. These findings indicate that STZ diabetes produces, at an early stage, changes similar to those reported to occur in the human disease, e. g. a greater bladder capacity with unimpaired voiding function. The increased bladder capacity of STZ-rats seems largely, if not solely, ascribable to changes in physical properties of the detrusor muscle, thereby allowing accomodation of greater than normal volumes with similar increase of intraluminal pressure. No sign of diabetic neuropathy of the capsaicin-sensitive sensory nerves can be observed at this stage (7–9 weeks) of STZ diabetes. Send offprint requests to P. Santicioli at the above address  相似文献   
65.
Summary Ninety to ninety-five men (aged 27 to 46 years) from the police academy were the study subjects. Their prior habits of physical excercise, estimated aerobic capacity ( ), muscular performance, and thickness of subcutaneous fat were determined. The policemen were taller (181 cm vs 175 cm) and heavier (84 kg vs 74 kg) than the average 20- to 40-year-old Finnish man, and their (1 · min–1) was higher (3.41 1 · min–1 vs 2.96 1 min–1 The frequency of prior physical exercise significantly correlated with most of the variables studied. Those policemen who did not exercise at all (n = 12) were inferior to the average 20- to 40-year-old Finnish man on all the physical fitness tests, whereas the results of the most active policemen (n = 23) were clearly higher. The results indicate that the selection of heavier and taller men for police training guarantees a certain absolute level of physical performance capacity. However, the physical activity involved in police work is insufficient to maintain a high level of physical fitness, which must be achieved through participation in regular and effective physical training.  相似文献   
66.
67.
ObjectivesTo examine the effectiveness of game-based interventions compared with usual care on health-related outcomes for acutely hospitalized older patients.DesignSystematic review of randomized controlled trials (RCT) and nonrandomized trials.Setting and ParticipantsAdults aged 65 years or older admitted to an Acute Care for Elderly unit were selected.MeasuresHealth-related outcomes (eg, functional capacity, quality of life, adherence to treatment).ResultsFour RCTs were included in the review. The interventions were based on the implementation of serious-game programs using Nintendo Wii in acute medical patients. Across the included studies, no significant differences were observed between groups on functional capacity and health-related quality of life. Significant differences were found between groups on the adherence to treatment (in favor of the control group), but no differences were obtained in other outcomes such as enjoyment and motivation.Conclusions and ImplicationsIn general, there is very limited evidence for the efficacy to reach conclusions about the effects of game-based interventions on health-related outcomes in acutely hospitalized older patients. Future studies are needed to improve our knowledge in the field; however, we consider that these strategies should be considered in the future complementary to usual care.  相似文献   
68.
结节病患者肺功能变化研究   总被引:2,自引:0,他引:2  
目的:肺结节病患者肺功能测试的研究。方法:40例肺结节病患者不同时期肺功能测试结果和应用激素的回顾分析。结果:显示此类患者有限性通气功能障碍并伴有弥散功能下降和小气道功能受限,PaO2明显下降,pH升高,PaCO2也有下降的趋势。激素治疗结果显示,患者的MMF有明显的提高。其它肺功能指标如VC,RV,RV/TLC,MVV,FEV1,DLCO等都有升高的趋势。结论:VC,RV,MMF,DLCO,DLCO/VA等对诊断结节病的病情发展有直接参考价值,而MMF在糖皮质激素治疗后有显著的变化,提高MMF对结节病的治疗和预后具有动态参考价值。  相似文献   
69.
目的 :研究葡萄籽提取物对四氯化碳 (CCl4 )引起的脂质过氧化反应和抗氧化能力的影响。方法 :通过对大鼠的体内实验 ,测定大鼠肝和脑组织中由 CCl4 诱导产生的过氧化脂质生成物丙二醛(MDA) (TBA法 )的含量、血清中的超氧化物歧化酶 (SOD) (比色法 )活性和血清中总抗氧化能力(T- AOC) (比色法 )。结果 :葡萄籽提取物可明显降低大鼠肝和脑组织中 MDA的生成量 ,明显升高血清中 SOD活性和 T- AOC。结论 :葡萄籽提取物具有明显的抗氧化作用。  相似文献   
70.
为研究金丝桃的抗脂质过氧化作用,用分光光度法测定了金丝桃提取物对大鼠离体组织匀浆的脂质过氧化及由Fe2+-H2O2体系、Fe2+-VitC体系和Fe2+-Cys体系诱导的脂质过氧化的抑制作用。发现金丝桃提取物对大鼠肝、心、肾组织匀浆脂质过氧化和线粒体诱导的脂质过氧化具有抑制作用并表现出剂量依赖关系,而且提取物F003的抑制作用要强于F004、F005的抑制作用。认为金丝桃具有较好的抗脂质过氧化作用,具有进一步研究与开发价值。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号