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   740篇
  免费   48篇
  国内免费   4篇
耳鼻咽喉   9篇
儿科学   31篇
妇产科学   12篇
基础医学   81篇
口腔科学   19篇
临床医学   141篇
内科学   129篇
皮肤病学   7篇
神经病学   60篇
特种医学   24篇
外科学   93篇
综合类   8篇
一般理论   1篇
预防医学   66篇
眼科学   6篇
药学   46篇
中国医学   2篇
肿瘤学   57篇
  2023年   6篇
  2022年   7篇
  2021年   8篇
  2020年   19篇
  2019年   20篇
  2018年   23篇
  2017年   23篇
  2016年   30篇
  2015年   22篇
  2014年   20篇
  2013年   42篇
  2012年   59篇
  2011年   58篇
  2010年   22篇
  2009年   25篇
  2008年   53篇
  2007年   59篇
  2006年   57篇
  2005年   46篇
  2004年   43篇
  2003年   43篇
  2002年   30篇
  2001年   4篇
  2000年   3篇
  1999年   4篇
  1998年   6篇
  1997年   3篇
  1996年   5篇
  1995年   5篇
  1994年   8篇
  1993年   5篇
  1992年   4篇
  1991年   1篇
  1990年   1篇
  1988年   2篇
  1987年   3篇
  1985年   3篇
  1984年   1篇
  1983年   2篇
  1982年   1篇
  1981年   2篇
  1980年   1篇
  1979年   1篇
  1978年   3篇
  1977年   1篇
  1976年   1篇
  1975年   1篇
  1974年   2篇
  1973年   3篇
  1971年   1篇
排序方式: 共有792条查询结果,搜索用时 15 毫秒
31.
New spirometric reference equations for Swedish adults are required. Three different older sets of reference equations clinically used in Sweden have various drawbacks and the recently published ‘The Global Lung Function 2012 (GLI) equations’ have been shown not to be adequate for Swedish normal, healthy non‐smokers. We have recently concluded that a piecewise linear model presented by Lubinski and Gólczewski accurately describes the distribution of spirometric variables in a large Swedish random population sample. This piecewise linear model also offers the important advantage of implementing easily physiologically interpretable coefficients. The present study aimed at presenting piecewise linear reference equations for Swedish adults based on a random population sample of 6685 individuals aged 25–75 years. Predicted normal values by the piecewise linear reference equations and lower limit normal (LLN) were compared with the three reference equations frequently used clinically in Sweden and the GLI equations. We found predicted normal values according to the present piecewise linear reference equations close to 100% predicted normal as expected, whereas the other equations either overestimated or underestimated normal subjects. Concerning LLN, the present equations, i.e. 1·645 × RSD, showed the least deviation from the expected 5% and, e.g., the GLI equations systematically identified too few subjects below LLN. We conclude that the present piecewise linear reference equations, based on a relatively large general population sample, ought to be considered for clinical use in Sweden. Application of 1·645 × RSD below predicted value gave an acceptably accurate LLN.  相似文献   
32.
33.
OBJECTIVE: The authors explored the effect of galantamine on behavioral symptoms in Alzheimer disease (AD). METHODS: Data were pooled from 2,033 subjects with mild-to-moderate AD who had participated in one of three randomized, double-blind, placebo-controlled trials of 3-, 5-, and 6-month durations. Subjects included in this post hoc analysis had received treatment with either placebo (N=686) or galantamine (N=1347) in total daily doses of 16 mg, 24 mg, or 32 mg. Behavioral symptoms were measured on the 10-item Neuropsychiatric Inventory (NPI). Four symptom clusters were defined a priori: 1) delusions, hallucinations; 2) agitation, depression, anxiety, apathy, irritability; 3) disinhibition, elation, aberrant motor behavior; 4) hallucinations, anxiety, apathy, aberrant motor behavior. RESULTS: At endpoint, mean changes from baseline in NPI scores were significantly different between galantamine-treated subjects and placebo-treated subjects, favoring galantamine for several measures: total NPI, individual domains of agitation/aggression, anxiety, disinhibition, and aberrant motor behavior, and Clusters 1, 3, and 4. The magnitude of the effect sizes was small. CONCLUSIONS: In this pooled sample of more than 2,000 subjects with mild-to-moderate AD, those who received galantamine therapy experienced modestly better, but statistically significant, outcomes in their behavioral symptoms than placebo-treated subjects. The cluster of hallucinations, anxiety, apathy and aberrant motor behaviors may represent a specific group of cholinergic-responsive behavioral symptoms.  相似文献   
34.
35.
Oxygen consumption, lactate production and tissue contents of ATP, phosphocreatine (PCr) and lactate were measured following readdition of K+ to K+-depleted rat portal veins, in order to study the energy turnover associated with Na+/K+ pumping. During incubation in K+-free medium at 37° C spontaneous contractions disappeared in 10–20 min. Readdition of K+ (5.9 mM) after 40 min K+-free incubation caused hyperpolarization of the cell membrane for the first 5–10 min and then gradual depolarization with return of spontaneous action potentials and contractions by 10–20 min. During the first 4–6 min after K+ readdition aerobic lactate production was about doubled and then gradually returned to the original level (0.17 mol/min g) at about 20 min. The increase in glycolytic rate was prevented by 1 mM ouabain. In contrast, O2 consumption (in K+-free medium, 0.38 mol/min g) rose by about 10% when K+ was added and this increase lasted about 5 min. By 8 min after K+ addition the increased glycolysis and oxidative phosphorylation had accounted for each about the same amount of extra ATP generation over that extrapolated from the steady rate before K+ addition. The average total increase in ATP turnover in the first 8 min was 15%. During this period there was no change in the cellular content of ATP, PCr, or extractable ADP. The results indicate that Na+/K+ pumping utilizes a relatively small share of the total energy turnover in the vascular smooth muscle but is to a large extent dependent on aerobic glycolysis and therefore a major site of carbohydrate usage.  相似文献   
36.
Introduction. Firefighters are taught that heat, oxygen deprivation, andcarbon monoxide (CO) are the primary threats to life in residential structure fires, andthey are taught to search for victims on the fire floor first, andthen floors above. The objective of this study was to gather data regarding oxygen, CO, andheat conditions inside a realistic house fire, to examine the validity of these teachings. Methods. During six live-burn training evolutions in a two-story wood-frame house, metering for oxygen levels, CO levels, andtemperature was conducted. Except where noted, all readings were taken 24 inches off the floor, to simulate the location of a crawling victim or firefighter. Readings were hand-recorded on a convenience basis by firefighters stationed outside the building, near the meters. Results. Of the 35 oxygen levels recorded, the lowest was 18.2%, with only 12 readings below 20%. Three of 16 first-floor readings were below 20%, whereas nine of 19 second-floor readings were below 20% (p = 0.07). First- andsecond-floor readings were comparable (mean 20.3% vs. 19.9%, p = 0.11). Except for one reading of 1,870 ppm, all CO readings at the ceiling exceeded the 2,000-ppm limit of the meters. Of the 34 CO levels recorded 24 inches off the floor, 29 (76%) exceeded the permissible exposure limit of 50 ppm, with the highest reading being 1,424 ppm, well above the “immediately dangerous to life andhealth” level of 1,200 ppm. None of the 20 CO levels recorded on the first floor exceeded the 30-minute exposure limit of 800 ppm, whereas seven of 14 second-floor readings exceeded this limit (p < 0.001). While ceiling temperatures frequently exceeded the 1,000°F limit of the meters, none of 16 readings taken 24 inches off the floor exceeded 137°F. First- andsecond-floor temperatures were comparable (mean 88.5°F vs. 90.1°F, p = 0.9). Conclusions. In residential structure fires, CO poses a greater threat to victims andfirefighters than does oxygen deprivation or heat. Emergency medical services personnel should consider CO toxicity in all fire victims. Conditions on the floor above a fire are at least as adverse as those on the fire floor.  相似文献   
37.
A human liver complementary DNA expression library was screened using sera from patients with high titers of autoantibodies, to search for clones expressing major autoantigens that are relevant in connective tissue diseases. One of the clones isolated expressed a major epitope(s) that was immunoreactive with anti-U1 RNP sera, as shown by several techniques. Affinity-purified autoantibodies from the cloned RNP protein specifically recognized the 68-kd U1 RNP protein of HeLa cell nuclear extracts. All sera containing anti-U1 RNP antibodies detected by immunodiffusion, counterimmuno-electrophoresis, or immunoblotting also recognized the cloned RNP protein. The RNP antigen-expressing bacterial colonies and the partially purified cloned RNP fusion protein have been applied to fast and sensitive immunologic assays for the detection and quantification of anti-U1 RNP antibodies.  相似文献   
38.
39.
Five percent of patients on dual antiplatelet therapy after coronary artery stent implantation will need non-cardiac surgery within the first year of therapy, and many more will need surgery later on. A function assay that evaluates platelet reactivity and inhibition by drug therapy is beneficial for such patients. Platelet Mapping assay (PM?) using the TEG® analyzer was tested in surgical patients. After IRB approval, 60 patients on combined aspirin and clopidogrel therapy were consented and enrolled. The TEG® maximal amplitude (MA) and the percentage (%) platelet inhibition were recorded and analyzed. Fifty-seven patients (mean age 65.7 ± 10.9 years) had preoperative data only. Distribution of preoperative ADP (43.6 ± 24.4 %) and AA inhibition (52.8 ± 30.2 %) was determined, as well as for the preoperative MA ADP (43.1 ± 15.9 mm) and MA AA (37.2 ± 19.6 mm), showing an offset of the effect of both medications starting from day 3. Patients with complete pre- and postoperative data were stratified depending on duration off antiplatelet therapy (≤3 days, 3–7 days and >7 days): n = 27, ADP % preop inhibition (43.2 ± 21.6 %), ADP % postop inhibition (32.3 ± 18.3 %), p = 0.048. Distribution of immediate pre- and post- ADP and AA % inhibitions, showing a possible reduction in Δ of inhibition for clopidogrel at 3 days, were also assessed. Conclusion: According to the findings, the TEG® PM? assay might be a feasible approach to objectively evaluate the effects of aspirin and clopidogrel during the perioperative period and potentially guide drug management.  相似文献   
40.
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