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   2044篇
  免费   197篇
  国内免费   44篇
耳鼻咽喉   9篇
儿科学   66篇
妇产科学   49篇
基础医学   217篇
口腔科学   25篇
临床医学   216篇
内科学   496篇
皮肤病学   95篇
神经病学   88篇
特种医学   169篇
外科学   158篇
综合类   65篇
一般理论   2篇
预防医学   218篇
眼科学   19篇
药学   233篇
中国医学   1篇
肿瘤学   159篇
  2021年   26篇
  2020年   19篇
  2019年   26篇
  2018年   36篇
  2017年   28篇
  2016年   21篇
  2015年   30篇
  2014年   51篇
  2013年   56篇
  2012年   77篇
  2011年   75篇
  2010年   51篇
  2009年   58篇
  2008年   67篇
  2007年   101篇
  2006年   94篇
  2005年   96篇
  2004年   67篇
  2003年   64篇
  2002年   71篇
  2001年   70篇
  2000年   80篇
  1999年   62篇
  1998年   33篇
  1997年   28篇
  1996年   26篇
  1995年   21篇
  1994年   21篇
  1993年   32篇
  1992年   44篇
  1991年   45篇
  1990年   43篇
  1989年   47篇
  1988年   38篇
  1987年   30篇
  1986年   39篇
  1985年   32篇
  1984年   28篇
  1983年   27篇
  1980年   17篇
  1979年   26篇
  1977年   24篇
  1976年   22篇
  1975年   14篇
  1974年   14篇
  1973年   33篇
  1972年   22篇
  1971年   23篇
  1970年   18篇
  1969年   20篇
排序方式: 共有2285条查询结果,搜索用时 15 毫秒
1.
Vaccination is a vital health care initiative to prevent individual and population infection. To increase vaccination rates the federal government implemented the ‘No Jab, No Pay’ policy, where eligibility for several government benefits required children to be fully vaccinated by removing ‘conscientious objections’ and expanding the age range of children whose families receive benefits. This study assesses the impact of this policy at a local area within a single medical practice community in NSW, Australia. A retrospective clinical audit was performed between 2012 and 2017 on a single general practice's vaccination records for children ≤19 years. Catch-up vaccinations were assessed based on age at vaccination. Incidence of catch-up vaccinations was assessed for each of four years before and two years after the implementation of the ‘No Jab, No Pay’ policy in January 2016, along with the age of children and vaccination(s) given. Catch-up vaccinations were assessed temporally either side of implementation of ‘No Jab, No Pay’. Comparing the average annual vaccination catch-up incidence rate of 6.2% pre-implementation (2012–2015), there was an increase to 9.2% in 2016 (p < .001) and 7.8% in 2017 (p = .027). Secondary outcome measurement of catch-up vaccination incidence rates before (2012–2015) and after (2016–2017) ‘No Jab, No Pay’ implementation showed statistically significant increases for children aged 8–11 years (3.2%–5.6%, p = .038), 12–15 years (7.5%–14.7%, p < .001) and 16–19 years (3.3%–10.2%, p < .001) along with a statistically significant reduction in children aged 1–3 years (11.4%–6.2%, p = .015). Also, catch-up rates for DTPa significantly increased after program implementation. This study demonstrates that the Australian federal government vaccination policy ‘No Jab, No Pay’ was coincident with an increase in catch-up vaccinations within a rural NSW community served by one medical practice, especially for older children.  相似文献   
2.
ObjectiveTo evaluate changes in insurance status among emergency department (ED) patients presenting in the two years immediately before and after full implementation of the Affordable Care Act (ACA).MethodsWe evaluated National Hospital Ambulatory Medical Care Survey (NHAMCS) Emergency Department public use data for 2012–2015, categorizing patients as having any insurance (private; Medicare; Medicaid; workers' compensation) or no insurance. We compared the pre- and post-ACA frequency of insurance coverage—overall and within the older (≥65), working-age (18–64) and pediatric (<18) subpopulations—using unadjusted odds ratios with 95% confidence intervals. We also conducted a difference-in-differences analysis comparing the change in insurance coverage among working-age patients with that observed for older Medicare-eligible patients, while controlling for sex, race and underlying temporal trends.ResultsOverall, the proportion of ED patients with any insurance did not significantly change from 2012 to 2013 to 2014–2015 (74.2% vs 77.7%) but the proportion of working-age adult patients with at least one form of insurance increased significantly, from 66.0% to 71.8% (OR 1.31, CI: 1.13–1.52). The difference-in-differences analysis confirmed the change in insurance coverage among working-age adults was greater than that seen in the reference population of Medicare-eligible adults (AOR 1.70, CI: 1.29–2.23). The increase was almost entirely attributable to increased Medicaid coverage.ConclusionIn the first two years following full implementation of the ACA, there was a significant increase in the proportion of working-age adult ED patients who had at least one form of health insurance. The increase appeared primarily associated with expansion of Medicaid.  相似文献   
3.
Usher syndrome: clinical findings and gene localization studies   总被引:3,自引:0,他引:3  
The issue of genetic heterogeneity is a critical problem in the localization of the gene(s) for Usher syndrome. Based on the data obtained on families studied to date, the differences between type I and type II Usher syndrome appear quite distinct with regard to auditory and vestibular function. Although the majority of families can be confidently diagnosed as typical type I or type II, clinical investigations revealed four families with findings that did not fit into either of the two more common subtypes. These findings emphasize the critical importance of an in-depth clinical analysis concomitant with the linkage investigation to assure accurate subtyping of Usher syndrome. Based on an analysis of only those families with definite type I or type II Usher syndrome, approximately 17% of the genome can be excluded as a potential site of the gene for type I, and 14% can be excluded as the site for the type II gene. This study will continue until the Usher gene(s) is successfully localized.  相似文献   
4.
外科医生和手术室人员经常接触手术设备产生的烟气,病人也会暴露于烟气中,特别是腹腔镜手术中产生的烟气滞留于腹腔内这一密闭空间并被吸收.这些烟气是一种与香烟烟气相似的毒性物质,然而对这种毒性物质的影响还未引起足够重视.应该采取必要措施尽可能减少手术中烟气的不良影响.  相似文献   
5.
6.
取代四氢异喹啉衍生物的合成及其生物活性   总被引:7,自引:0,他引:7  
粉防己碱有钙拮抗作用,临床试用于治疗高血压,其裂解产物钙拮抗作用降低,但有α-肾上腺素能受体拮抗作用,本文以裂解物为先导化合物设计合成了两类取代的四氢异喹啉衍生物Ⅲ及Ⅳ。初步药理试验表明:大部分化合物有α-肾上腺素能受体拮抗作用,少数化合物钙拮抗活性有所增强,其中Ⅲ15,19对正常麻醉大鼠有一定的降压作用、Ⅳ17,19对实验性动物心律失常有明显的保护作用。部分化合物量化计算表明:化合物与α1-受体作用方式可能是形成电荷转移复合物。  相似文献   
7.
8.
The monitoring of micronutrients and the relationship between dietary intake and micronutrient status prior to and after surgery in patients with histologically proven gastrointestinal adenocarcinoma, both weight-stable and weight-losing (> 7.5% of their pre-illness weight) has been studied and the results compared to controls. Plasma vitamin C and red blood cell thiamine levels were significantly lower in weight-losing cancer patients when compared to their weight-stable counterparts (P < 0.05 and P < 0.02 respectively). Weight-losing patients had a lower vitamin C (P < 0.05) and thiamine (P < 0.002) intake, and a higher elevation in plasma C-reactive protein and a lower prealbumin level (P < 0.02), when compared to both weight-stable cancer patients and controls. Plasma vitamin C, prealbumin and C-reactive protein levels remained unchanged after curative resections of the tumours compared to a preoperative value, and there was a highly significant correlation between plasma vitamin C and dietary intake of vitamin C. This study suggests that the lower vitamin C and thiamine status in weight-losing gastrointestinal cancer patients prior to surgery is due to a lower micronutrient intake and an acute phase response to their illness. Dietary intake of vitamin C appears to be the major factor in determining plasma vitamin C concentration following curative surgical resection.  相似文献   
9.
OBJECTIVE--To audit the use of extended skills by South Glamorgan Ambulance crew in attempted resuscitations from out-of-hospital cardio-respiratory arrest, in terms of successful discharge of patients from hospital and the accuracy with which agreed protocols were applied. Design-Retrospective analysis of ambulance report forms, electrocardiograph rhythm strips, casualty cards and discharge summaries during 26 months (1st May 1987-30th June 1989). SETTING--A mixed urban and semi-rural area of 187 square miles with a population of 396,000. RESULTS--There were 274 attempted resuscitations. Seven patients (2.5%) were managed for primary respiratory arrest and 3 were discharged. In 98 patients (35.8%) the initial resuscitation protocol was for ventricular fibrillation: 26 were admitted and 17 were discharged. In 169 patients (61.7%) the initial resuscitation protocol was for asystole or electromechanical dissociation: 11 were admitted and 1 discharged. The majority of patients who were successfully discharged from hospital were those in ventricular fibrillation who responded to defibrillation alone (13 survivors). Drug administration may have played a role in the successful resuscitation of the remainder. Endotracheal intubation was successful in 94.7% and vein cannulation in 87.7% of attempts. There were deviations from the ventricular fibrillation protocol in 27 cases (27.5%) and from the asystole protocol in 27 cases (16.0%). CONCLUSION--Survival rates for ventricular fibrillation managed by these personnel were satisfactory with early defibrillation. Defibrillation alone was responsible for the majority of successful resuscitations. The additional benefit of drug administration appears small, though potentially important. The majority of patients were in asystole by the time the ambulance arrived. IMPLICATIONS--Extended trained crews use their skills effectively. The most important skill is defibrillation. Further studies are required to explain the high proportion of patients found in asystole. The performance of individual ambulance personnel should be assessed prospectively, because agreed resuscitation protocols are not always followed.  相似文献   
10.
Winkler  ML; Olsen  WL; Mills  TC; Kaufman  L 《Radiology》1987,165(1):203-207
Two fast magnetic resonance (MR) imaging techniques, advanced Fourier and partial-flip imaging, were used at 0.35 T to examine 21 patients with suspected intracranial lesions; the results were quantitatively compared with a conventional spin-echo study. Both of the fast MR techniques yielded a fourfold reduction in imaging time per section. The advanced Fourier sequence showed contrast that was identical to the conventional spin-echo study with signal-to-noise ratios of 58% and 57% for the first and second echoes, respectively. The partial-flip sequence showed a contrast of 109% and 57% for lesions versus substantia alba, and 107% and 78% for substantia grisea versus substantia alba relative to the first and second echoes of the conventional spin-echo study. The partial-flip sequence was particularly sensitive to magnetic susceptibility; this produced artifacts that may undermine the usefulness of partial flip for routine screening in certain parts of the brain. However, this susceptibility significantly improved the detection of intracranial hemorrhage when compared with the spin-echo sequence, particularly when combined with phase mapping of the partial-flip study.  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