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   386篇
  免费   25篇
耳鼻咽喉   6篇
儿科学   23篇
妇产科学   6篇
基础医学   23篇
口腔科学   3篇
临床医学   59篇
内科学   115篇
皮肤病学   28篇
神经病学   16篇
特种医学   5篇
外科学   45篇
综合类   13篇
一般理论   3篇
预防医学   18篇
眼科学   1篇
药学   44篇
肿瘤学   3篇
  2016年   5篇
  2015年   6篇
  2014年   3篇
  2013年   6篇
  2010年   15篇
  2009年   7篇
  2006年   2篇
  2005年   3篇
  2002年   2篇
  2000年   3篇
  1999年   3篇
  1998年   6篇
  1997年   18篇
  1996年   15篇
  1995年   12篇
  1994年   12篇
  1993年   10篇
  1992年   10篇
  1991年   14篇
  1990年   10篇
  1989年   19篇
  1988年   10篇
  1987年   3篇
  1986年   4篇
  1985年   9篇
  1983年   11篇
  1982年   4篇
  1978年   2篇
  1977年   3篇
  1976年   4篇
  1972年   2篇
  1969年   2篇
  1968年   4篇
  1967年   3篇
  1966年   2篇
  1965年   2篇
  1963年   1篇
  1962年   1篇
  1961年   1篇
  1960年   1篇
  1959年   15篇
  1958年   16篇
  1957年   18篇
  1956年   25篇
  1955年   22篇
  1954年   20篇
  1951年   1篇
  1949年   14篇
  1948年   16篇
  1946年   2篇
排序方式: 共有411条查询结果,搜索用时 31 毫秒
1.
2.
We examine and refine the Fagerström Tolerance Questionnaire (FTQ; Fagerström, 1978). The relation between each FTQ item and biochemical measures of heaviness of smoking was examined in 254 smokers. We found that the nicotine rating item and the inhalation item were unrelated to any of our biochemical measures and these two items were primary contributors to psychometric deficiencies in the FTQ. We also found that a revised scoring of time to the first cigarette of the day (TTF) and number of cigarettes smoked per day (CPD) improved the scale. We present a revision of the FTQ: the Fagerström Test for Nicotine Dependence (FTND).  相似文献   
3.
Current antitachycardia systems such as the automatic implantable cardioverter/defibrillator (AICD), detect tachyarrhythmias primarily by sensing rate and thereby perform inadequately in differentiating hemodynamically stable from unstable arrhythmias. As a result, these devices may discharge during stable tachycardias (such as sinus tachycardia), causing discomfort to the patient and depleting the device's limited energy supply. If a parameter which could reflect the particular hemodynamic state of a tachycardia were incorporated into the sensing algorithm of these systems, function may be more hemodynamically precise and discharge specificity may be improved.  相似文献   
4.
5.
Subchronic and Chronic Inhalation Toxicity of Antimony Trioxide in the Rat   总被引:2,自引:0,他引:2  
Fischer 344 rats were exposed by inhalation to Sb2O3 (antimonytrioxide) dust at exposure levels of 0, 0.25, 1.08, 4.92, and23.46 mg/m3 for 6 hr/day, 5 days/week for 13 weeks followedby a 27-week observation period. Subsequently, an inhalationon-cogenicity study was conducted at exposure levels of 0, 0.06,0.51, and 4.50 mg/m3 for 12 months followed by a 12-month observationperiod. The Sb2O3 in the subchronic study had a mass medianaerodynamic diameter (MMAD) of 3.05 ± 0.21 microns (mean± SD) with a geometric standard deviation (GSD) of 1.57± 0.06. In the chronic study, the MMAD was 3.76 ±0.84 and the GSD was 1.79 ± 0.32. Except for the eyes,no adverse clinical observations were attributed to Sb2O3 ineither study. In the subchronic study, corneal irregularitieswere seen after about 2 weeks of exposure and did not abateduring the observation period. In the chronic study, ophthalmoscopicevaluation at 24 months revealed a dose-related increase incataracts of 11, 24, 28, and 32% (both sexes combined) for eachgroup, respectively. Body weights were significantly lower (6%)than the control group's weights in the 23.46 mg/m3 males inthe subchronic study. These rats did not recover this weightduring the 27-week observation period. Body weights of the femalesin both studies and males in the chronic study were unaffected.There were no Sb2O3 effects on clinical chemistry or he-matologyin either study. Mean absolute and relative lung weights weresignificantly increased in the 4.92 and 23.46 mg/m3 groups inthe subchronic study. The 23.46 mg/m3 group's lung weights didnot recover to control levels during the 27-week observationperiod. Lung weights for rats in the chronic study were unaffected.Microscopic changes in the lungs in the subchronic and chronicstudy were limited to subacute-chronic interstitial inflammation,increased numbers of alveolar-in-traalveolar macrophages, foreignmaterial in the alveolar-in-traalveolar macrophages in the peribronchialand perivascular (chronic study only) lymphoid aggregates andin the peribronchial lymph nodes, granulomatous inflammation/granulomas,and fibrosis. In the chronic study, any observed neoplasms occurredwith comparable incidence among all groups and were within thehistorical range for controls. Clearance of Sb2O3 from the lungwas burden dependent and was reduced by 80/ in the 4.50 mg/m3group in the chronic study. The previously reported studies,which found Sb2O3 to be a carcinogen, were run at higher lungburdens. Under the exposure conditions of the current study,Sb2O3 was not a carcinogen.  相似文献   
6.
7.
BackgroundThe incidence of peripartum cardiomyopathy (PPCM) is known through referral center databases that may be affected by referral, misclassification, and other biases. We sought to determine the community-based incidence and natural history of PPCM using the Rochester Epidemiology Project.Methods and ResultsIncident cases of PPCM occurring between January 1, 1970, and December 31, 2014, were identified in Olmsted County, Minnesota. A total of 15 PPCM cases were confirmed yielding an incidence of 20.3 cases per 100,000 live births in Olmsted County, Minnesota. Clinical information, disease characteristics, and outcomes were extracted from medical records in a 27-county region of the Rochester Epidemiology Project including Olmsted County and matched in a 1:2 ratio with pregnant women without PPCM. A total of 48 women were identified with PPCM in the expanded 27-county region. There was 1 death and no transplants over a median of 7.3 years of follow-up. Six of the 23 women with subsequent pregnancies developed recurrent PPCM, all of whom recovered. Migraine and anxiety were identified as novel possible risk factors for PPCM.ConclusionsThe population-based incidence of PPCM was 20.3 cases per 100,000 live births in Olmsted County, Minnesota. Cardiovascular outcomes were generally excellent in this community cohort.  相似文献   
8.
9.
The United States Environmental Protection Agency's Integrated Risk Information System (IRIS) includes hazard identification and dose-response assessment values developed by Agency scientists. Uncertainty factors (UFs) are used in the development of IRIS values to address the lack of information in five main areas. The standard UFs account for interspecies uncertainty (UFA) and intraspecies variability (UFH). The UFA addresses uncertainty related to the extrapolation of data from animals to humans, whereas the UFH addresses variability amongst individuals (i.e., intrahuman). Additional UFs have been employed to account for database incompleteness, extrapolations from a lowest-observed-adverse-effect level in the absence of a no-observed-adverse-effect level (UFL), and subchronic-to-chronic extrapolation (UFS). A sixth UF designated as “other uncertainty factors” (UFO) has also been applied in place of the UFL to account for uncertainty with the adversity of points of departure obtained using benchmark dose modeling. This review will discuss how UFL, UFS, and UFO have been applied in IRIS assessments, along with the rationale used to describe the choice of UF values that deviate from the standard default of 10.  相似文献   
10.
The Effect of Etiocholanolone on Granulocyte Kinetics   总被引:1,自引:0,他引:1  
The effect of etiocholanolone on granulocyte kinetics in 12 hematologicallynormal patients has been investigated using the technic of 3H-DFP labelingof autologous blood in vitro.

Baseline determinations of the total blood granulocyte pool (TBGP), thecirculating pool (CGP), and the marginated pool (MGP) were performed.The values for the total blood granulocyte pools were similar to those previously reported. Following the administration of etiocholanolone, there was a98 per cent increase in the TBGP, which was considered to be due to mobilization of granulocytes from the bone marrow reserve. There was no change inthe ratio of CGP to MGP.

These studies suggest that etiocholanolone may be a useful agent for theestimation of bone marrow reserve.

Submitted on November 21, 1966 Accepted on April 13, 1967  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