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   685篇
  免费   34篇
  国内免费   1篇
耳鼻咽喉   11篇
儿科学   7篇
妇产科学   11篇
基础医学   119篇
口腔科学   30篇
临床医学   85篇
内科学   136篇
皮肤病学   5篇
神经病学   107篇
特种医学   25篇
外科学   60篇
综合类   1篇
预防医学   35篇
眼科学   1篇
药学   39篇
中国医学   3篇
肿瘤学   45篇
  2022年   5篇
  2021年   5篇
  2020年   8篇
  2019年   8篇
  2018年   12篇
  2017年   5篇
  2016年   12篇
  2015年   12篇
  2014年   16篇
  2013年   44篇
  2012年   28篇
  2011年   34篇
  2010年   16篇
  2009年   24篇
  2008年   37篇
  2007年   44篇
  2006年   42篇
  2005年   40篇
  2004年   40篇
  2003年   33篇
  2002年   41篇
  2001年   13篇
  2000年   9篇
  1999年   10篇
  1998年   10篇
  1997年   15篇
  1996年   11篇
  1995年   9篇
  1994年   7篇
  1993年   10篇
  1992年   7篇
  1991年   7篇
  1990年   10篇
  1989年   11篇
  1988年   4篇
  1987年   15篇
  1986年   10篇
  1985年   7篇
  1984年   8篇
  1983年   6篇
  1982年   3篇
  1981年   7篇
  1979年   2篇
  1978年   5篇
  1976年   2篇
  1974年   4篇
  1973年   3篇
  1972年   3篇
  1967年   2篇
  1965年   1篇
排序方式: 共有720条查询结果,搜索用时 31 毫秒
71.
Several studies show that asthma mortality in children and adolescents increased until the mid-1990s, after which it has slightly decreased worldwide. The objective of this study was to describe the mortality rates of childhood asthma in Finland, and to analyze patient characteristics to identify predisposing factors for fatal asthma exacerbation among children and adolescents during 1976-1998 (2004). All death certificates where asthma or related respiratory tract disease was coded as the underlying cause of death were reviewed for those under 20 years of age. Health care records and autopsy reports were evaluated to validate the cause of death and to identify any predisposing factors. In all, there had been 28 asthma deaths. The validity of the death certificates proved to be good as only 7% were misclassified. Death occurred either in the very young children or adolescents: the median age in the group of <12 years (n = 15) was 3.3 years while the median age in the group of >12 years (n = 13) was 18.1 years. The fatal exacerbations occurred mostly during summer and early autumn. Clinical triggers, recorded for 14/22 patients with available patient records, included respiratory infection, (12) use of ibuprofen despite known allergy (1), and exercise after visiting a horse stable (1). The severity of the disease was discernible in 21 patients: severe in 15, moderate in 5, and mild in 1 patient. Inhaled corticosteroids were not used as maintenance or periodic therapy in 12/22 patients, of whom 4 had died during the 1990s. In conclusion, asthma mortality in Finnish children and adolescents was rare and its incidence remained stable. The validity of the death certificate diagnoses proved to be good. Poor asthma management and non or undertreatment with inhaled corticosteroids were risk factors for fatal asthma.  相似文献   
72.
Although psychoanalysts welcome children's story creations in the clinical setting, psychoanalytic investigators have given them limited attention. This author examined stories that 40 children, aged 8 to 14, narrated to the Thematic Apperception Test blank card presented in psychological evaluation. The stories depicted playful use of reality as a new development; specific dynamic factors influencing thematic content; humor in latency and self-referencing in (pre-)adolescence as age-specific characteristics. The findings further our understanding of conscious fantasy.  相似文献   
73.
Objective The pharmacokinetics of nimodipine following enteral administration in the early phase after subarachnoid haemorrhage (SAH) has not been described. If a sufficient absorption could be achieved with enterally administered nimodipine, this would be more feasible dosage form and result in a significant reduction in pharmaceutical costs given that the parenteral formulation of nimodipine currently used is tenfold more expensive than the enteral formulation. Methods This was a pilot study in which 17 patients with aneurysmal SAH were randomly assigned to receive nimodipine within 24 h after initial bleeding either as an 60 mg tablet/suspension at 4-h intervals, or as a continuous intravenous infusion of 2 mg/h. Serum nimodipine concentrations were measured during the 4 h following the first dose, and at 24 and 72 h on a validated gas chromatography mass spectrometer (GC-MS). Results Nimodipine AUC values (expressed in μg min/ml) were lower in the eight SAH patients receiving enteral nimodipine [AUC0–4 range: 0.13–5.4 (median: 0.32); AUC24–28 range: 0.16–6.1 (0.71); AUC72–76 range: 0.47–20.6 (1.9)] than in the nine patients receiving a continuous intravenous infusion of nimodipine [AUC0–4 range: 2.4–4.9 (3.4), p = 0.059; AUC24–28 range: 4.7–10.3 (7.3), p = 0.001; AUC72–76 range: 3.4–8.6 (6.9), p = 0.001]. In three of five good-grade SAH patients receiving nimodipine tablets the AUC values were comparable to those of the intravenous administration, but in two good-grade patients with tablets and in all three poor-grade (Hunt&Hess, grade IV) SAH patients receiving the suspension, the rate and extent of nimodipine absorption was negligible. Conclusion This pilot study indicates that the rate and extent of nimopidine absorption following enteral administration in some acute SAH patients could be negligible, and this may particularly be the case in patients with a decreased level of consciousness.  相似文献   
74.
Unsaturated polyester (UP) cement caused allergic contact dermatitis in car repair work. The resin was a condensate of polyols and maleic anhydride with reactive solvent, auxiliary substances, and inorganic reinforcement substances. To identify the causative chemicals, the cement was tested on a sensitized patient. For analysis, samples of the resin were eluted with acetone and eluted with hexane to precipitate inorganic material and large polyester molecules. The eluate was evaporated. The remainder, dissolved in acetone, was separated into fractions on silica plates by thin layer chromatography (TLC). On the developed (hexane/chloroform, 15/85) plates, 20 bands were obtained under UV-light at 254 nm. Samples of the bands were scraped and used for patch testing. The scraping at a retention factor (Rf) of 0.24 caused a skin reaction. The bands at this retention were removed from six plates, combined, eluted with acetone and purified again by TLC. The purified fraction mixed in petrolatum in the dilution series was used for conclusive patch testing on the patient. An allergic reaction was induced at down to 0.003% wt/wt. According to MS and IR analyses, the isolated compound was diethyleneglycol maleate (DEGM, MW204). In addition to the resin part, the sanding dust also contained this monomer.  相似文献   
75.
76.
Respiratory syncytial virus (RSV) bronchiolitis in infancy can lead to bronchial hyper-reactivity or recurrent obstructive bronchitis. The aim of the present study was to determine whether the type of treatment has an influence on respiratory status after RSV bronchiolitis. The study involved 117 infants (mean age 2.6 months), who needed hospital treatment because of RSV bronchiolitis. The patients were divided randomly into three groups. All received the same symptomatic treatment. Group I children received symptomatic treatment only, group II children were treated for 7 days with inhaled budesonide, 500 µg three times per day, administered via a nebulizer. Group III children received nebulized budesonide, 500 µg twice per day for two months. Follow-up consisted of out-patient check-ups 2 and 6 months after the infection, and telephone contact two years after the infection. Statistically significant differences were seen between the groups. In group I 37% of the children had asthma, in group II 18%, and in group III 12%. According to the present study it seems that inhaled corticosteroid treatment during and after the acute phase of infant RSV bronchiolitis may have a beneficial effect on subsequent bronchial wheezing tendency.  相似文献   
77.
A radioimmunoassay (RIA) has been developed for the determination of picogram amounts of aescine, an anti-inflammatory and anti-oedematous glycoside mixture from unpurified extracts of Aesculus hippocastanum. Practically no interference is observed for various potentially crossreacting compounds. This RIA covers the range 100 pg-50 ng, within which acceptable accuracy and precision are obtained.  相似文献   
78.
The objective of this study is to investigate the effect at the season of the time of surgery on the survival of brain tumor patients. The population studied consisted of 101 patients (39 males and 62 females), gathered from a geographically large area in northern Finland (from 64°N to 70°N), aged between 20 and 82 years, with a solitary primary brain tumor treated surgically at the Oulu Clinic for Neurosurgery, Oulu University Hospital. The distribution of tumor surgery dates and mean hours of sunshine hours was analyzed by bimonthly periods. When comparing the proportion of deceased patients of all patients operated in each bimonthly period, a significant bimonthly peak in deaths was found in patients operated during the period of February to March (ratio 1.7, 95% CI 1.1–2.3). More than half of the patients who died during the peak period had grade III–IV gliomas. In 40% of the cases, the surgery time of deceased brain tumor patients occurred in the bimonthly period following the four darkest months of the year with the lowest amount of sunshine in northern Finland. The relation of low vitamin D level in the etiology and course of the disease as well as in treatment settings deserves further study.  相似文献   
79.
The resistance patterns and macrolide resistance mechanisms of 910 Finnish invasive pneumococci isolated during 1999 and 2000 were studied. Macrolide resistance was detected in 6.9% of isolates. Penicillin resistance was detected in 1.5% of isolates, and penicillin intermediate resistance was detected in 4.0% of isolates. Active macrolide efflux, mediated by the mef(A) gene, was the most common macrolide resistance mechanism. Four macrolide-resistant isolates had mutations in rRNA or ribosomal protein L22.  相似文献   
80.
Polyamines and polyamine-metabolizing enzyme activities in human semen   总被引:1,自引:0,他引:1  
The content of polyamines putrescine, spermidine and spermine as well as the activities of some polyamine-metabolizing enzymes have been analyzed from normal and pathological human semen samples. Seminal fluid from semen samples showing no apparent abnormalities in semen analyses contained about 0.2 mM of putrescine, 0.1 mM of spermidine and 3 mM of spermine. Seminal plasma was found to be an exceptionally rich source of diamine oxidase activity (EC 1.4.3.6). In addition, polyamine-synthesizing enzyme activities, S-adenosylmethionine decarboxylase and spermidine synthase, were invariably found in seminal plasma. Spermatozoa contained very low or undetectable activities of 5-adenosylmethionine decarboxylase and spermidine synthase; however, a definitive diamine oxidase activity was found also in the cellular component of the semen.The activity of diamine oxidase, and especially that of spermidine synthase, was relatively high in semen samples having low sperm density (less than 20 × 106 spermatozoa per ml). With increasing number of spermatozoa there was a slight decrease in both activities, but as the sperm count exceeded 100 × 106 per ml the activity of diamine oxidase and spermidine synthase sharply increased. The concentration of spermine in seminal plasma showed only minor changes in relation to the number of spermatozoa in semen, the changes being roughly opposite as compared to the changes of the enzyme activities. A significant negative correlation was found between the concentration of putrescine and the activity of diamine oxidase in seminal plasma.Several properties of diamine oxidase from human seminal plasma were found to be comparable to those of other mammalian diamine oxidases. Using radioactive putrescine as the substrate the enzyme activity was inhibited by addition of unlabelled histamine, cadaverine, spermidine and spermine. The enzyme was also powerfully inhibited by various carbonyl reagents and methylglyoxal bis-(guanylhydrazone).  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