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   1889篇
  免费   81篇
  国内免费   15篇
耳鼻咽喉   22篇
儿科学   61篇
妇产科学   52篇
基础医学   199篇
口腔科学   27篇
临床医学   364篇
内科学   252篇
皮肤病学   27篇
神经病学   210篇
特种医学   232篇
外科学   112篇
综合类   47篇
一般理论   2篇
预防医学   138篇
眼科学   25篇
药学   111篇
肿瘤学   104篇
  2022年   12篇
  2021年   24篇
  2020年   24篇
  2019年   23篇
  2018年   27篇
  2017年   27篇
  2016年   43篇
  2015年   38篇
  2014年   69篇
  2013年   74篇
  2012年   53篇
  2011年   81篇
  2010年   57篇
  2009年   60篇
  2008年   61篇
  2007年   81篇
  2006年   77篇
  2005年   74篇
  2004年   60篇
  2003年   56篇
  2002年   44篇
  2001年   42篇
  2000年   36篇
  1999年   53篇
  1998年   53篇
  1997年   54篇
  1996年   46篇
  1995年   46篇
  1994年   29篇
  1993年   31篇
  1992年   37篇
  1991年   41篇
  1990年   36篇
  1989年   36篇
  1988年   42篇
  1987年   45篇
  1986年   43篇
  1985年   34篇
  1984年   28篇
  1983年   14篇
  1982年   21篇
  1981年   18篇
  1980年   25篇
  1979年   6篇
  1978年   16篇
  1977年   23篇
  1976年   15篇
  1975年   12篇
  1970年   5篇
  1969年   5篇
排序方式: 共有1985条查询结果,搜索用时 15 毫秒
21.
Interest in the potential cardiovascular (CV) benefits of omega-3 polyunsaturated fatty acids (Ω-3) began in the 1940s and was amplified by a subsequent landmark trial showing reduced CV disease (CVD) risk following acute myocardial infarction. Since that time, however, much controversy has circulated due to discordant results among several studies and even meta-analyses. Then, in 2018, three more large, randomized trials were released—these too with discordant findings regarding the overall benefits of Ω-3 therapy. Interestingly, the trial that used a higher dose (4 g/day highly purified eicosapentaenoic acid (EPA)) found a remarkable, statistically significant reduction in CVD events. It was proposed that insufficient Ω-3 dosing (<1 g/day EPA and docosahexaenoic acid (DHA)), as well as patients aggressively treated with multiple other effective medical therapies, may explain the conflicting results of Ω-3 therapy in controlled trials. We have thus reviewed the current evidence regarding Ω-3 and CV health, put forth potential reasoning for discrepant results in the literature, highlighted critical concepts such as measuring blood levels of Ω-3 with a dedicated Ω-3 index and addressed current recommendations as suggested by health care professional societies and recent significant scientific data.  相似文献   
22.
BackgroundRisk assessment of patients with acute COVID-19 in a telemedicine context is not well described. In settings of large numbers of patients, a risk assessment tool may guide resource allocation not only for patient care but also for maximum health care and public health benefit.ObjectiveThe goal of this study was to determine whether a COVID-19 telemedicine risk assessment tool accurately predicts hospitalizations.MethodsWe conducted a retrospective study of a COVID-19 telemedicine home monitoring program serving health care workers and the community in Atlanta, Georgia, with enrollment from March 24 to May 26, 2020; the final call range was from March 27 to June 19, 2020. All patients were assessed by medical providers using an institutional COVID-19 risk assessment tool designating patients as Tier 1 (low risk for hospitalization), Tier 2 (intermediate risk for hospitalization), or Tier 3 (high risk for hospitalization). Patients were followed with regular telephone calls to an endpoint of improvement or hospitalization. Using survival analysis by Cox regression with days to hospitalization as the metric, we analyzed the performance of the risk tiers and explored individual patient factors associated with risk of hospitalization.ResultsProviders using the risk assessment rubric assigned 496 outpatients to tiers: Tier 1, 237 out of 496 (47.8%); Tier 2, 185 out of 496 (37.3%); and Tier 3, 74 out of 496 (14.9%). Subsequent hospitalizations numbered 3 out of 237 (1.3%) for Tier 1, 15 out of 185 (8.1%) for Tier 2, and 17 out of 74 (23%) for Tier 3. From a Cox regression model with age of 60 years or older, gender, and reported obesity as covariates, the adjusted hazard ratios for hospitalization using Tier 1 as reference were 3.74 (95% CI 1.06-13.27; P=.04) for Tier 2 and 10.87 (95% CI 3.09-38.27; P<.001) for Tier 3.ConclusionsA telemedicine risk assessment tool prospectively applied to an outpatient population with COVID-19 identified populations with low, intermediate, and high risk of hospitalization.  相似文献   
23.
We describe a case of papuloerythroderma. This is a distinctive clinical entity characterized by pruritus, red-brown flat-topped papules exhibiting the "deck-chair" sign, eosinophilia, and lymphopenia. We propose that the Langerhans cell may have a central role in the pathogenesis of papuloerthroderma and we describe an excellent response to photochemotherapy.  相似文献   
24.
OBJECTIVE: Because the survival rate has increased for extremely low birth weight neonates, many have raised the concern that the rate of developmental disability among survivors will also increase. To address this concern, we analyzed changes over time in survival and major neurosensory impairment in a sample of extremely low birth weight infants born between July 1, 1979, and June 30, 1994. METHODS: The study sample included 513 infants with birth weights of 501 to 800 g who were cared for in either of the two neonatal intensive care units that serve a 17-county region in northwest North Carolina and who were born to mothers residing in that region. At 1 year of age (corrected for gestation), survivors were examined by a pediatrician and were tested using the Bayley Scales of Infant Development. Major neurosensory impairment was defined as cerebral palsy, a Bayley Mental Developmental Index <68, or blindness. A total of 209/216 (97%) of survivors were examined at 1 year of age. Epoch of birth was defined as follows: epoch 1, July 1, 1979 to June 30, 1984; epoch 2, July 1, 1984 to June 30, 1989; and epoch 3, July 1, 1989 to June 30, 1994. RESULTS: Survival rates for epochs 1, 2, and 3 were, respectively, 24/120 (20%), 63/175 (36%), and 129/218 (59%). In contrast, the proportions with a major neurosensory impairment did not increase over time; rates for successive epochs were 6/24 (25%), 17/61 (28%), and 26/124 (21%). Rates of cerebral palsy were 3/24 (13%), 12/61 (20%), and 9/124 (7%); rates of delayed mental development were 4/24 (17%), 12/61 (20%), and 17/124 (14%); and rates of blindness were 2/24 (8%), 0/62, and 5/124 (4%), respectively. CONCLUSIONS: This analysis suggests that the increasing survival of extremely low birth weight neonates since the late 1970s has not resulted in an increased rate of major developmental problems identifiable at 1 year of age.  相似文献   
25.
26.
PURPOSE: Trastuzumab is effective in treating human epidermal growth factor receptor 2 (HER2) -positive breast cancer, but it increases frequency of cardiac dysfunction (CD) when used with or after anthracyclines. PATIENTS AND METHODS: National Surgical Adjuvant Breast and Bowel Project trial B-31 compared doxorubicin and cyclophosphamide (AC) followed by paclitaxel with AC followed by paclitaxel plus 52 weeks of trastuzumab beginning concurrently with paclitaxel in patients with node-positive, HER2-positive breast cancer. Initiation of trastuzumab required normal post-AC left ventricular ejection fraction (LVEF) on multiple-gated acquisition scan. If symptoms suggestive of congestive heart failure (CHF) developed, source documents were blindly reviewed by an independent panel of cardiologists to determine whether criteria were met for a cardiac event (CE), which was defined as New York Heart Association class III or IV CHF or possible/probable cardiac death. Frequencies of CEs were compared between arms. RESULTS: Among patients with normal post-AC LVEF who began post-AC treatment, five of 814 control patients subsequently had confirmed CEs (four CHFs and one cardiac death) compared with 31 of 850 trastuzumab-treated patients (31 CHFs and no cardiac deaths). The difference in cumulative incidence at 3 years was 3.3% (4.1% for trastuzumab-treated patients minus 0.8% for control patients; 95% CI, 1.7% to 4.9%). Twenty-seven of the 31 patients in the trastuzumab arm have been followed for > or = 6 months after diagnosis of a CE; 26 were asymptomatic at last assessment, and 18 remained on cardiac medication. CHFs were more frequent in older patients and patients with marginal post-AC LVEF. Fourteen percent of patients discontinued trastuzumab because of asymptomatic decreases in LVEF; 4% discontinued trastuzumab because of symptomatic cardiotoxicity. CONCLUSION: Administering trastuzumab with paclitaxel after AC increases incidence of CHF and lesser CD. Potential cardiotoxicity should be carefully considered when discussing benefits and risks of this therapy.  相似文献   
27.
The effect of iron-deficiency anemia on myocardial mechanics and energetics was studied in 10 anesthetized bealge puppies. Nine littermates served as controls. Left ventricular/body weight ratio was increased 14.2% (P less than 0.05) and cardiac index 36.5% (P less than 0.02) in the anemic puppies. Heart rate, mean systolic pressure, myocardial lactate extraction coefficient, and lactic dehydrogenase isozymes were similar in both groups. Contractile state measured in vivo (pressure-velocity curves) and in isolated muscles (isotonic force-velocity curves) was virtually identical in the littermate groups. Despite markedly increased coronary blood flow in the anemia animals, oxygen consumption per unit weight of myocardium was the same in both groups. Contractile element efficiency averaged 18.3% in 10 adult mongrel dogs studied in a similar fashion and was 27.1% and 39.8% in the normal puppies and anemic puppies, respectively. The oxygen cost of internal or force-generating work was similar among the three groups of dogs. It is concluded that the volume load produced by iron-deficiency anemia was associated with a normal contractile state, normal unit myocardial oxygen consumption, no evidence of chronic anaerobiosis, and a high contractile element efficiency, perhaps as a consequence of increased diastolic fiber stretch.  相似文献   
28.
29.
A total of 10,000 U.S. households in 25 standard metropolitan statistical areas and 25 counties were included in a study to determine the household use of pesticides in the United States. More than 8,200 households granted an interview. Nine of every ten households in the United States used some type of pesticide in their house, garden, or yard. Households in the southeastern United States used the most pesticides. Although more than 500 different pesticide formulations were used by the sampled households, 15 pesticides accounted for 65.5% of all pesticides reported in this study. Thirteen of these 15 pesticides were insecticides, one was a herbicide, and one was a rodentickle.  相似文献   
30.
Purpose: To report a case of Vogt–Koyanagi–Harada (VKH) disease associated with hepatitis B vaccination.

Methods: Case report.

Results: A 43-year-old Caucasian male presented with a three-week history of blurry vision, pain, photophobia, and redness in both eyes. Three days prior to the onset of symptoms, he had received the hepatitis B virus vaccine. Clinical evaluation revealed multifocal placoid lesions in the posterior pole, choroidal thickening, and serous macular detachment. Targeted laboratory investigations were negative for infectious or autoimmune markers. After treatment with oral corticosteroids, the patient had resolution of symptoms with near-total recovery of visual function. The patient later reported systemic findings of hearing loss, tinnitus, and integumentary changes. A diagnosis of VKH disease was made and inflammation was managed with oral corticosteroids followed by methotrexate for long-term disease control.

Conclusions: VKH disease is an inflammatory condition primarily affecting the choroid, retinal pigment epithelium, and outer retina. The underlying etiology is unclear, but it can be associated with a viral prodrome suggesting an infectious trigger in a genetically susceptible individual. Our case suggests that hepatitis B vaccination may trigger a similar inflammatory response.  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