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   942505篇
  免费   68710篇
  国内免费   1374篇
耳鼻咽喉   13126篇
儿科学   24698篇
妇产科学   23541篇
基础医学   134543篇
口腔科学   28934篇
临床医学   81566篇
内科学   186027篇
皮肤病学   19490篇
神经病学   73221篇
特种医学   37250篇
外国民族医学   79篇
外科学   153726篇
综合类   18122篇
现状与发展   1篇
一般理论   239篇
预防医学   62745篇
眼科学   21519篇
药学   73174篇
  3篇
中国医学   2196篇
肿瘤学   58389篇
  2018年   9379篇
  2017年   7335篇
  2016年   8086篇
  2015年   9222篇
  2014年   12443篇
  2013年   18044篇
  2012年   24863篇
  2011年   25778篇
  2010年   15293篇
  2009年   14673篇
  2008年   25211篇
  2007年   26370篇
  2006年   27055篇
  2005年   25975篇
  2004年   25016篇
  2003年   24020篇
  2002年   23518篇
  2001年   55009篇
  2000年   56810篇
  1999年   47243篇
  1998年   10839篇
  1997年   9580篇
  1996年   9684篇
  1995年   9013篇
  1994年   8361篇
  1993年   7677篇
  1992年   35689篇
  1991年   34091篇
  1990年   32885篇
  1989年   32047篇
  1988年   29144篇
  1987年   28377篇
  1986年   26420篇
  1985年   25280篇
  1984年   17935篇
  1983年   15218篇
  1982年   7841篇
  1981年   6825篇
  1979年   15848篇
  1978年   10655篇
  1977年   9082篇
  1976年   7910篇
  1975年   8671篇
  1974年   10501篇
  1973年   9910篇
  1972年   9400篇
  1971年   8874篇
  1970年   8456篇
  1969年   7949篇
  1968年   7223篇
排序方式: 共有10000条查询结果,搜索用时 45 毫秒
81.
Fibroepithelial polyps (FEPs) are common, benign intraoral lesions that tend to develop slowly at predictable sites, often in response to local irritation or trauma. Historical precedent often results in referral to oral and maxillofacial surgery (OMFS) departments for biopsy, often irrespective of symptoms, and histological assessment. OMFS and pathology services are struggling to cope with an increasing workload that will potentially lead to widespread delays to diagnosis and treatment. Over the past 20 years, clinical pathways and guidance have been developed to ensure that healthcare interventions, such as the removal of third molars, tonsils, skin tags, and benign moles, are evidence-based, have a net patient benefit, and ensure the best use of finite NHS resources. However, no such guidance exists for intraoral lesions and we regard this as an oversight. We analysed the removal of 682 FEPs over a seven-year period and report sensitivities of 92.4% for a “confirmed clinical suspicion of an FEP” and 99.7% for a “confirmed clinical suspicion of a benign diagnosis”. The incidence of non-benign disease was 0.3%. Primary care dentists should be able to diagnose and monitor FEPs and refer only if symptoms are serious or in high-risk patients or sites. Adopting this practice across the UK could free up to 1825 four-hour OMFS clinics, 405 hours of consultant histopathologists’ time, and recurring savings to the NHS estimated to be in the region of £620 000/annum. We believe that the removal of FEPs should be reclassified as an “intervention not normally funded”, and the time and resources put to better use treating patients with lesions of questionable pathology.  相似文献   
82.
Zygomatic implant treatment is widely applied for severe maxillary atrophy to help rehabilitate the maxillary dentition. This retrospective study was performed to evaluate the actual radiographic bone–implant contact (rBIC) lengths of zygomatic implants. The records of 28 patients who underwent zygomatic implant surgery and subsequent follow-up examinations between August 2013 and September 2018 in the Department of Oral and Maxillofacial Surgery, Taipei Tzu Chi Hospital were reviewed. The surgeries were performed by a single surgeon using the same treatment protocol. All patients had a computed tomography scan at 1 year after the surgery. Using three-dimensional imaging software, an investigator measured the rBIC lengths of 66 implants and documented their clinical status. The implant survival rate was 100%. The mean rBIC length was significantly longer in male patients than in female patients (20.80 ± 5.88 mm versus 17.79 ± 6.34 mm; P = 0.028). The mean rBIC length of double zygomatic implants was significantly longer when compared to that of single implants (21.11 ± 6.23 mm versus 17.75 ± 5.85 mm; P = 0.027). This article is novel in reporting the exact rBIC lengths of zygomatic implants in a clinical setting. The results showed that zygomatic implants are a viable treatment modality for full-mouth rehabilitation.  相似文献   
83.
The aim of this study was to analyse the effect of body mass index (BMI), both low and high values, on the perioperative complication rate in patients with oral squamous cell carcinoma (OSCC). The medical records of 259 patients operated between 2014 and 2017 for OSCC were reviewed. Univariate and multivariate analyses were performed. Sixty of the 259 patients developed 87 complications. Low or high BMI was not associated with the perioperative complication rate. A longer operating time and increased blood loss were associated with a higher perioperative complication rate and higher Clavien–Dindo grade. Low BMI, American Society of Anesthesiologists score 2 and 3, a longer operating time, and increased blood loss were associated with a longer hospital stay. Low BMI was associated with a longer hospital stay. Neither low nor high BMI was associated with the perioperative complication rate. A longer operating time and increased blood loss were associated with a higher perioperative complication rate and higher Clavien–Dindo grade.  相似文献   
84.
85.
86.
87.
88.

Background

The purpose of the study was to evaluate the association between fetal echocardiographic measurements and the need for intervention (primary coarctation repair, staged coarctation repair, or catheter intervention) in prenatally diagnosed coarctation of the aorta.

Methods

A single-centre retrospective cohort study (2005-2015) of 107 fetuses diagnosed with suspected coarctation of the aorta in the setting of an apex-forming left ventricle and antegrade flow across the mitral and aortic valves.

Results

Median gestational age at diagnosis was 32 weeks (interquartile range, 23-35 weeks). Fifty-six (52%) did not require any neonatal intervention, 51 patients (48%) underwent a biventricular repair. In univariable analysis, an increase in ascending aorta (AAo) peak Doppler flow velocity (odds ratio [OR], 1.40 [95% confidence interval [CI], 1.05-1.91] per 20 cm/s; P = 0.03) was associated with intervention. No intervention was associated with larger isthmus size (OR, 0.23; P < 0.001), transverse arch diameter (OR, 0.23; P < 0.001), and aortic (OR, 0.72; P = 0.02), mitral (OR, 0.58; P = 0.001), and AAo (OR, 0.53; P < 0.001) z-scores. In multivariable analysis, higher peak AAo Doppler (OR, 2.51 [95% CI, 1.54-4.58] per 20 cm/s; P = 0.001) and younger gestational age at diagnosis (OR, 0.81 [95% CI, 0.70-0.93] per week; P = 0.005) were associated with intervention, whereas a higher AAo z-score (OR, 0.65 [95% CI, 0.43-0.94] per z; P = 0.029) and transverse arch dimension (OR, 0.44 [95% CI, 0.18-0.97]; P = 0.05) decreased the risk of intervention.

Conclusions

In prenatally suspected coarctation, the variables associated with intervention comprised smaller AAo and transverse arch size, earlier gestational age at diagnosis, and the additional finding of a higher peak AAo Doppler.  相似文献   
89.
90.

Background

Payers frequently rely on budget impact model (BIM) results to help determine drug coverage policy and its effect on their bottom line. It is unclear whether BIMs typically overestimate or underestimate real-world budget impact.

Objective

We examined how different modeling assumptions influenced the results of 6 BIMs from the Institute for Clinical and Economic Review (ICER).

Study Design

Retrospective analysis of pharmaceutical sales data.

Methods

From ICER reports issued before 2016, we collected estimates of 3 BIM outputs: aggregate therapy cost (ie, cost to treat the patient population with a particular therapy), therapy uptake, and price. We compared these against real-world estimates that we generated using drug sales data. We considered 2 classes of BIM estimates: those forecasting future uptake of new agents, which assumed “unmanaged uptake,” and those describing the contemporaneous market state (ie, estimates of current, managed uptake and budget impact for compounds already on the market).

Results

Differences between ICER's estimates and our own were largest for forecasted studies. Here, ICER's uptake estimates exceeded real-world estimates by factors ranging from 7.4 (sacubitril/valsartan) to 54 (hepatitis C treatments). The “unmanaged uptake” assumption (removed from ICER's approach in 2017) yields large deviations between BIM estimates and real-world consumption. Nevertheless, in some cases, ICER's BIMs that relied on current market estimates also deviated substantially from real-world sales data.

Conclusions

This study highlights challenges with forecasting budget impact. In particular, assumptions about uptake and data source selection can greatly influence the accuracy of results.  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