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   30912篇
  免费   2173篇
  国内免费   688篇
耳鼻咽喉   251篇
儿科学   982篇
妇产科学   286篇
基础医学   3826篇
口腔科学   1432篇
临床医学   2366篇
内科学   2503篇
皮肤病学   5678篇
神经病学   821篇
特种医学   1002篇
外国民族医学   3篇
外科学   5355篇
综合类   3664篇
预防医学   1201篇
眼科学   535篇
药学   2154篇
  22篇
中国医学   687篇
肿瘤学   1005篇
  2024年   134篇
  2023年   673篇
  2022年   795篇
  2021年   1058篇
  2020年   1245篇
  2019年   1008篇
  2018年   1017篇
  2017年   972篇
  2016年   1011篇
  2015年   970篇
  2014年   1712篇
  2013年   2193篇
  2012年   1498篇
  2011年   1733篇
  2010年   1488篇
  2009年   1412篇
  2008年   1407篇
  2007年   1533篇
  2006年   1348篇
  2005年   1287篇
  2004年   1097篇
  2003年   935篇
  2002年   834篇
  2001年   737篇
  2000年   522篇
  1999年   578篇
  1998年   495篇
  1997年   495篇
  1996年   433篇
  1995年   375篇
  1994年   292篇
  1993年   261篇
  1992年   255篇
  1991年   210篇
  1990年   195篇
  1989年   169篇
  1988年   159篇
  1987年   167篇
  1986年   144篇
  1985年   150篇
  1984年   123篇
  1983年   81篇
  1982年   116篇
  1981年   95篇
  1980年   82篇
  1979年   79篇
  1978年   30篇
  1977年   31篇
  1976年   44篇
  1975年   27篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
The research evaluated an intervention strategy designed to prevent skin cancer in young adolescents. The intervention used parents as change agents to effectively communicate the risks of skin cancer and encourage their children to avoid high-risk sun-related behaviors while increasing positive sun-safe behaviors. Three hundred and forty parents in two regions of the United States were educated about the dangers of risky sun behaviors and how to convey information about skin cancer prevention to their children. Parents were then encouraged to talk with their children about these issues over a 1-month period prior to the onset of summer. Following this time period, children whose parents received and implemented the intervention materials were compared with a control sample of 129 children. These two groups were matched on age, gender, and school on number of sunburns and sunburn severity, attitudes and beliefs, and sunbathing behavior. Children in the treatment condition differed significantly from controls in the predicted directions on all outcome variables. The findings are discussed in terms of reducing skin cancer risk behaviors of children via parent-based intervention approaches.  相似文献   
82.
A 7-month-old boy with gross motor delay and failure to thrive presented with rhabdomyolysis following an acute asthmatic episode. During hospitalization an electrocardiographic conversion to a Wolff-Parkinson-White type 1 (WPW) pattern took place. Duchenne muscular dystrophy (DMD) was suspected based on elevated creatine kinase (CK) serum levels, muscle biopsy, and family history. The diagnosis was confirmed by molecular analysis, which documented a deletion corresponding to cDNA probe 1-2a in the dystrophin gene, in the propositus and in an affected male cousin of his mother. “Idiopathic” hyperCKemia was found in the propositus, his father, and 5 of his relatives. We suggest that the unusually early and severe manifestations of DMD in this patient may be related to the coincidental inheritance of the maternal DMD gene and of a paternal gene, causing hyperCKemia. © 1995 Wiley-Liss, Inc.  相似文献   
83.
远端蒂腓肠神经营养血管皮瓣与肌皮瓣的临床应用与改进   总被引:6,自引:0,他引:6  
目的:报道应用远端蒂腓肠神经营养血管皮瓣,肌皮瓣修复小腿下段及足踝部软组织缺损的可行性安全性和临床效果。方法:对42例以远端蒂腓肠神经营养血管(肌)皮瓣修复小腿下段及足踝部不同原因所致软组织缺损病例进行总结分析。本组男36例,女6例;年龄最大75岁、最小6岁;皮瓣最大面积17.0cm×15.0cm,最小6.0cm×5.0cm,其中12例皮瓣面积在10.0cm×10.0cm以上;6例设计为肌皮瓣(腓肠肌外侧头),肌瓣最大为10.0cm×7.0cm×2.0cm,最小为6.0cm×5.0cm×1.0cm。结果:所有病例术后皆出现不同程度的皮瓣肿胀,暗道较明道者明显。2例大皮瓣经行小隐静脉远端结扎仍出现肿胀、色暗,皮瓣近侧1/3坏死。皮瓣边缘坏死3例,换药治愈。部分坏死需行植皮者3例。36例术后伤口I期愈合,骨外露软件组织缺损覆盖修复满意,6例II期愈合,其中糖尿病,地中海贫血各一例。结论:(1)远端蒂腓肠神经营养血管皮瓣转位修复小腿下1/3及足踝部缺损创面,极有临床实用价值;(2)设计切取腓肠神经营养血管肌皮瓣修复小腿及足踝填充感染创腔是可行的;(3)但对其皮瓣及所携带的肌瓣究竟切取多大面积是安全的、肌瓣的血运机理以及远端蒂筋膜皮瓣中小隐静脉干是否结扎,何处结扎等问题仍有待进一步研究。  相似文献   
84.
Two methods of estimating body heat storage were compared under differing conditions of clothing, training, and acclimation to heat. Six male subjects underwent 8 weeks of physical training [60–80% of maximal aerobic power ( ) for 30–45 min · day–, 3–4 days · week–1 at < 25 °C dry bulb (db)] followed by 6 consecutive days of heat acclimation (45–55% for 60 min · day–1 at 40°C db, 30% relative humidity)]. Nine other male subjects underwent corresponding periods of control observation followed by heat acclimation. Before and after each treatment, subjects walked continuously on a treadmill (1.34 m · s–1, 2% grade) in a climatic chamber (40°C db, 30% relative humidity) for an average of 118 min (range 92–120 min) when wearing normal light combat clothing and for an average of 50 min (range 32–68 min) when wearing protective clothing resistant to nuclear, biological, and chemical agents. The heat storage was determined calorimetrically (by the balance of heat gains and losses) and thermometrically [by the conventional equations, using one or two set(s) of relative weightings for the rectal temperature (T re) to mean skin temperature sk of 4:1 and 4:1, 2:1 and 4:1, or 2:1 and 9:1 in thermoneutral and hot environments, respectively]. sk was calculated from 12-site measurements, weighted according to the regional distribution of body surface area and the first eigenvectors of principal component analysis. There were only minor differences (< 5%) between the heat storage values calculated by given weighting factors forT re and sk, whether the individual coefficients were derived from estimates of regional surface area or principal component methodologies. When wearing normal clothing, no significant differences were found between the two estimates of heat storage (calorimetry vs thermometry with an invariant relative weighting of 4:1) in any experimental condition, with one specific exception: when wearing protective clothing, thermometry underestimated the heat storage by 24–31%. This underestimation was attenuated by using two sets of relative weightings of 2: 1 and 4: 1 or 2: 1 and 9: 1. The results suggest that when subjects wearing protective clothing are transferred from thermoneutral to hot environments, the accuracy of thermometric estimates of heat storage can be improved by using two sets of weighting factors forT re and sk  相似文献   
85.
A variety of adverse reactions to local anesthetics has been described, some of which are thought to be allergic. Different protocols of prick and intradermal skin tests as well as subcutaneous challenge tests are used to select a local anesthetic which can safely be used. Their long-term effectiveness has not yet been assessed. Twenty-eight patients with a history of adverse reaction to local anesthetics were evaluated over a 3-year period. Loss of consciousness occurred in eight patients, skin reaction in nine, and vagal symptoms in eight. Various reactions were recorded in the remaining three patients. Rapid spontaneous recovery was the rule, suggesting that immediate allergic reaction and, in particular, anaphylactic reaction were unlikely. Investigation allowed the selection of a tolerated anesthetic in all cases. Reexposure occurred in 19 patients 16–50 months after evaluation and 6.8 ± 5.5 years after the first reaction. No patient presented a second reaction. In conclusion, adverse reactions to local anesthetics seem to be, in most cases, not allergic in nature. Evaluation protocols are effective in selecting an agent susceptible to tolerance, but are time consuming. However, they probably contribute to an important reassurance effect that is likely to increase tolerance to subsequent local anesthetic administration. Simplification of the protocols and better patient selection are proposed.  相似文献   
86.
The purpose of the present study was to assess the relationship between lateralization of body image and right versus left vasomotor activity. Fifteen right-handed female patients suffering from idiopathic Raynaud's disease demonstrated a relationship between the extent of right lateralization of body image and bilateral digital skin temperature during a controlled temperature stress test. In addition, subjects showing a reliable right side awareness demonstrated more unilateral vasospastic attacks in their right hand than their left hand white subjects showing no clear right lateralization by body image reported more left hand attacks than right hand attacks. These results were taken as consistent with previous work on the relationship between skin conductance and lateralization of body image.  相似文献   
87.
Sunbathing and sunscreen use, as well as related intentions, attitudes, beliefs, and knowledge, were assessed in 90 Southern Appalachian undergraduates. A large majority (75%) reported sunbathing, with more than half reporting sun lamp use. A slight majority (56.7%) reported some use of sunscreen. Subjects reporting an intention to tan spent more time sunbathing, both outside and under a sun lamp. Individuals reporting a sun protection intention had lighter tans and spent less time sunbathing. Sunbathing was predicted by perceptions of sunbathing as relaxing, while sun lamp use was predicted by more positive views of suntatns. Sunscreen use was predicted by more positive sun protection attitudes and less negative sunscreen attitudes.  相似文献   
88.
We report on 2 unrelated patients with Costello syndrome. The first is a 5-year-old girl with “coarse” face, nasal papillomata, redundant skin of feet and hands, hyperextensible hand and finger joints, curly hair, feeding problems due to oral motor apraxia, growth and psychomotor retardation. The second is a 3-year-old boy with “coarse” face, loose skin on hands and feet, curly hair, oral motor apraxia, severe growth and psychomotor retardation. In both patients urine sialic acid levels were found to be repeatedly high. The meaning of this biochemical abnormality is discussed. © 1993 Wiley-Liss, Inc.  相似文献   
89.
Simultaneous measurements of skin potential (SP) and skin resistance (SR) obtained from 20 male and 20 female adult subjects during 2 sessions held 2 to 9 days apart were used in studying (1) the correlation of change measurements and prestimulus level in the two measures, and (2) the amount of correlation between SP and SR using both simple difference and residual change scores in which the regression of poststimulus values on initial level (prestimulus) has been controlled. Correlations within Ss and correlations among Ss showed large individual variability, correlation differences between males and females, and high correlation between SP and SR change scores. Although the law of initial value (LIV) seemed to have little applicability to the measurement of electrodermal responses, the results underscored the need to control for contamination of change measures by initial level regardless of direction.  相似文献   
90.
BACKGROUND: Retrospective cohort study to evaluate differences in outcome when embryo transfer was performed either on day 2-3 (cleavage stage, CS-group) or on day 4-5 (blastocyst stage, BS-group). METHODS: A total of 1259 consecutive cycles yielding 500 live born babies performed at a single centre in Bregenz, Austria, were included. Main outcome measures were implantation and (multiple) pregnancy rates and neonatal outcome including birth defects. RESULTS: Total Pregnancy rate was 44% vs 28% (P < 0.001) and the total 'take home baby rate' was 37% vs 22% in the BS-group and the CS-group, respectively. Rate of multiple gestations (34% vs 17%, P = 0.001) was significantly higher among the BS-group, resulting in a higher rate of preterm deliveries < 36 weeks (26% vs 17%, P = 0.045). Female factor causing infertility (40% vs 21%, P < 0.001) was significantly higher among the BS-group. For the CS-group, rate of singleton pregnancies (83% vs 66%, P = 0.001) and idiopathic cause of infertility (34% vs 22%, P = 0.012) were significantly higher. No statistically significant differences were found in sex, Caesarean section rate, Apgar score and umbilical artery pH-values, total mean birth weight, admission rate to intensive care unit, days of hospitalization and number of minor and major birth defects. CONCLUSIONS: Our data suggest that blastocyst transfer may lead to a higher pregnancy rate with an overall better take-home baby rate (THBR) at the cost of higher rates of multiples and preterm deliveries.  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