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   4515389篇
  免费   310719篇
  国内免费   10240篇
耳鼻咽喉   64242篇
儿科学   148723篇
妇产科学   123692篇
基础医学   631067篇
口腔科学   129413篇
临床医学   415284篇
内科学   862708篇
皮肤病学   102589篇
神经病学   364232篇
特种医学   173928篇
外国民族医学   1646篇
外科学   673139篇
综合类   100031篇
现状与发展   7篇
一般理论   1708篇
预防医学   355862篇
眼科学   104156篇
药学   336900篇
  115篇
中国医学   9131篇
肿瘤学   237775篇
  2018年   48278篇
  2017年   36792篇
  2016年   42136篇
  2015年   47333篇
  2014年   65788篇
  2013年   99981篇
  2012年   133351篇
  2011年   142148篇
  2010年   85480篇
  2009年   80992篇
  2008年   132425篇
  2007年   141352篇
  2006年   142949篇
  2005年   138032篇
  2004年   133346篇
  2003年   128708篇
  2002年   124507篇
  2001年   207731篇
  2000年   214267篇
  1999年   181212篇
  1998年   53234篇
  1997年   46933篇
  1996年   46978篇
  1995年   45277篇
  1994年   41994篇
  1993年   39446篇
  1992年   144012篇
  1991年   140037篇
  1990年   136630篇
  1989年   132003篇
  1988年   121577篇
  1987年   119602篇
  1986年   112853篇
  1985年   108053篇
  1984年   81147篇
  1983年   68797篇
  1982年   40651篇
  1981年   36527篇
  1979年   74130篇
  1978年   52264篇
  1977年   44964篇
  1976年   41433篇
  1975年   44914篇
  1974年   53403篇
  1973年   51162篇
  1972年   48155篇
  1971年   44836篇
  1970年   41694篇
  1969年   39421篇
  1968年   36153篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
31.
32.
Objectives:To assess low dose altepase outcome and safety in comparison with a standard-dose regimen for acute ischemic stroke treatment in Egyptian patients.Materials:An observational prospective cohort non-randomized single blinded study was carried out during the period from November 2017 to December 2018. Eighty Egyptian acute ischemic stroke patients, all eligible for intravenous alteplase, were subdivided into 2 groups (40 patients in each group). Patients were thrombolysed at a dose of 0.6 mg/kg in the first group and 0.9 mg/kg in the second group. Both groups were compared in regard to safety and outcome. Safety was expressed by the rate of symptomatic intracranial hemorrhage (SICH) and 3 months mortality, while outcome was expressed by favorable outcomes at three months (modified Rankin Scale [mRS] of 0 to 2).Results:In the first group, 69.2% (n=27) achieved favorable outcomes at 90 days compared with 64.1% (n=25) in the second group (p=0.631). Ninety-day mortality was 5% (n=2) in the first group versus 2.5% (n=1) in the second group (p=0.556). Symptomatic intracranial hemorrhage was noted in 3 patients in the second group and zero patients in the first group (p=0.077).Conclusion:Low-dose alteplase could be a practical alternative for Egyptian populations with acute ischemic stroke especially in 3 to 4.5 hours window.

Cerebrovascular stroke is the second death and the seventh disability leading cause worldwide.1 Tissue-type plasminogen activator (tPA) alteplase was the first medication approved by the Food and Drug Administration (FDA) for the acute ischemic stroke (AIS) treatment on June 1996, within 3 hours of stroke onset with a recommended dose of 0.9 mg/kg (maximum 90mg).2 In 2008, the safety of using alteplase within 3 to 4.5 hours of stroke onset was approved by the Safe Implementation of Treatments in Stroke International Stroke Thrombolysis Registry (SITS -ISTR)3 and the European Cooperative Acute Stroke Study (ECASS III).4 However, thrombolytic therapy use has not been widely adopted, especially in developing countries. The restricted time window (3 to 4.5 hours), intracerebral hemorrhage (ICH) risk and the drug high cost are major obstacles preventing its broad application.5 Coagulation and fibrinolysis responses differ among different races, which increase symptomatic intracerebral hemorrhage (SICH) risk with standard-dose alteplase6 in Asian populations, many Asian neurologists considered alteplase low dose to be a better alternative for ischemic stroke treatment. Many studies had been conducted in order to prove the efficacy and safety of Alteplase low dose.7-9 One of these studies was the Japan Alteplase Clinical Trial (J-ACT) conducted by Yamaguchi et al10 According to this study, using a 0.6 mg/kg dose of intravenous recombinant tissue plasminogen activator (rtPA) in Japanese patients was safe and effective. Despite the relatively stroke high rate among Egyptian populations, 963/100,000 inhabitants, only less than 1% of stroke patients receive intravenous thrombolysis. A major reason for this is the drug cost.11,12 Low-dose regimens (0.6 mg/kg) use will lower the economic burden of thrombolytic therapy in the community and will greatly promote the implementation of this therapy in Egypt. Our study aim was to assess the outcome and safety of alteplase low dose in comparison to the standard-dose regimen in AIS treatment in Egypt.  相似文献   
33.
Background The impact of various breast-cancer treatments on patients with a BRCA2 mutation has not been studied. We sought to estimate the impact of bilateral oophorectomy and other treatments on breast cancer-specific survival among patients with a germline BRCA2 mutation.Methods We identified 664 women with stage I–III breast cancer and a BRCA2 mutation by combining five different datasets (retrospective and prospective). Subjects were followed for 7.2 years from diagnosis to death from breast cancer. Tumour characteristics and cancer treatments were patient-reported and derived from medical records. Predictors of survival were determined using Cox proportional hazard models, adjusted for other treatments and for prognostic features.Results The 10-year breast-cancer survival for ER-positive patients was 78.9% and for ER-negative patients was 82.3% (adjusted HR = 1.23 (95% CI, 0.62–2.45, p = 0.55)). The 10-year breast-cancer survival for women who had a bilateral oophorectomy was 89.1% and for women who did not have an oophorectomy was 59.0% (adjusted HR = 0.45; 95% CI, 0.28–0.72, p = 0.001). The adjusted hazard ratio for chemotherapy was 0.83 (95% CI, 0.65–1.53: p = 0.56).Conclusions For women with breast cancer and a germline BRCA2 mutation, positive ER status does not predict superior survival. Oophorectomy is associated with a reduced risk of death from breast cancer and should be considered in the treatment plan.Subject terms: Targeted therapies, Breast cancer  相似文献   
34.
ABSTRACT

This study focused on factors associated with antiretroviral therapy (ART) adherence and quality of life among transgenderwomen in Sao Paulo, Brazil, using univariable and adjusted analysis. Adherence was evaluated with a self-report tool and with HIV viral load (VL) measurement. PROQOL-HIV was used to assess quality of life. 106 TGW with median 41 years old were included; most were white (56%) and had >10 years of education (57%). Median time since HIV/AIDS diagnosis was 10 years. Overall, participants had high T CD4+ counts (median 659 cells/mm3) and most (75%) had undetectable HIV VL. 85% were considered adherent using self-report (95%CI 77-91), whereas 72% (95%CI 62-80) were considered adherent when self-report and undetectable HIV VL were analyzed jointly. Older age was associated with higher ART adherence; each year increase in age was associated with 5% higher odds of adherence (p?=?0.021). Quality of life ranged from good-excellent in 5 of 8 domains. Younger age, lower education, higher time since HIV diagnosis, comorbidities, illicit drugs use and depression were associated with lower PROQOL scores in specific domains in univariable analysis, while depression was also associated with lower total PROQOL score even after adjustment for age, comorbidities and time since HIV diagnosis (p?=?0.048).  相似文献   
35.
36.
Background The patient interval—the time patients wait before consulting their physician after noticing cancer symptoms—contributes to diagnostic delays. We compared anticipated help-seeking times for cancer symptoms and perceived barriers to help-seeking before and after the coronavirus pandemic.Methods Two waves (pre-Coronavirus: February 2020, N = 3269; and post-Coronavirus: August 2020, N = 1500) of the Spanish Onco-barometer population survey were compared. The international ABC instrument was administered. Pre–post comparisons were performed using multiple logistic and Poisson regression models.Results There was a consistent and significant increase in anticipated times to help-seeking for 12 of 13 cancer symptoms, with the largest increases for breast changes (OR = 1.54, 95% CI 1.22–1–96) and unexplained bleeding (OR = 1.50, 1.26–1.79). Respondents were more likely to report barriers to help-seeking in the post wave, most notably worry about what the doctor may find (OR = 1.58, 1.35–1.84) and worry about wasting the doctor’s time (OR = 1.48, 1.25–1.74). Women and older individuals were the most affected.Conclusions Participants reported longer waiting times to help-seeking for cancer symptoms after the pandemic. There is an urgent need for public interventions encouraging people to consult their physicians with symptoms suggestive of cancer and counteracting the main barriers perceived during the pandemic situation.Subject terms: Cancer epidemiology, Cancer screening, Signs and symptoms, Public health, Diagnosis  相似文献   
37.
AimsSelf-expanding metal stents provide rapid improvement of dysphagia in oesophageal cancer but are associated with complications. The aim of the present study was to test the effectiveness of an alternative treatment of combining biodegradable stents with radiotherapy.Materials and methodsA Simon two-stage single-arm prospective phase II trial design was used to determine the efficacy of biodegradable stents plus radiotherapy in patients with dysphagia caused by oesophagus cancer who were unsuitable for radical treatment. Fourteen patients were recruited and data from 12 were included in the final analyses.ResultsFive of 12 patients met the primary end point: one stent-related patient death; four further interventions for dysphagia within 16 weeks of stenting (41.7%, 95% confidence interval 15.2–72.3%). The median time to a 10-point deterioration of quality of life was 2.7 weeks. Nine patients died within 52 weeks of registration. The median time to death from any cause was 15.0 weeks (95% confidence interval 9.6–not reached).ConclusionThe high re-intervention observed, which met the pre-defined early stopping criteria, meant that the suggested alternative treatment was not sufficiently effective to be considered for a larger scale trial design. Further work is needed to define the place of biodegradable stents in the management of malignant oesophageal strictures.  相似文献   
38.

Background

With the worldwide spread of antibiotic resistance, delivering antibiotic susceptibility test (AST) results in a timely manner represents a major challenge. In cases of sepsis, rapid AST may facilitate early optimization of empiric antibiotic therapy. Disc diffusion is a well-standardized AST method, however 16 to 24?h are required to achieve an overall AST profile according to antimicrobial societies.

Methods

In this prospective pilot study, we evaluated the performance of Mueller-Hinton-Rapid-SIR (MHR-SIR) agar after 6–8?h of incubation in comparison with standard MH agar after 16?h of incubation directly on positive blood cultures caused by Enterobacteriaceae and Staphylococcus aureus from routine clinical microbiology.A total of 133 positive blood samples including 110 Enterobacteriaceae (83%) and 23 Staphylococcus aureus (17%) were tested in parallel by two direct AST methods, each using EUCAST breakpoints. For each combination bacterium and antibiotic, we compared the categorical agreement and the correlation between the diameters obtained by MHR-SIR and by standard MH.

Results

Our results showed 97.7% categorical agreement for Enterobacteriaceae, with 1.4% minor errors, 0.4% major errors and 0.5% very major errors. For S. aureus, we observed 97.8% categorical agreement, 1.9% minor errors, 0.3% major errors and no very major errors.

Conclusion

Our results showed excellent categorical agreement and correlations between diameters for MHR-SIR and standard MH methods. MHRSIR can predict the result of overall AST profile within 6–8?h with reliable results. AST is obtained on the same day the blood culture becomes positive, with a very moderate cost.  相似文献   
39.

Background

Nursing Home Compare (NHC) ratings, created and maintained by Medicare, are used by both hospitals and consumers to aid in the skilled nursing facility (SNF) selection process. To date, no studies have linked NHC ratings to actual episode-based outcomes. The purpose of this study was to evaluate whether NHC ratings are valid predictors of 90-day complications, readmission, and bundle costs for patients discharged to an SNF after primary total joint arthroplasty (TJA).

Methods

All SNF-discharged primary TJA cases in 2017 at a multihospital academic health system were queried. Demographic, psychosocial, and clinical variables were manually extracted from the health record. Medicare NHC ratings were then collected for each SNF. For patients in the Medicare bundle, postacute and total bundle cost was extracted from claims.

Results

Four hundred eighty-eight patients were discharged to a total of 105 unique SNFs. In multivariate analysis, overall NHC rating was not predictive of 90-day readmission/major complications, >75th percentile postacute cost, or 90-day bundle cost exceeding the target price. SNF health inspection and quality measure ratings were also not predictive of 90-day readmission/major complications or bundle performance. A higher SNF staffing rating was independently associated with a decreased odds for >75th percentile 90-day postacute spend (odds ratio, 0.58; P = .01) and a 90-day bundle cost exceeding the target price (odds ratio = 0.69; P = .02) but was similarly not predictive of 90-day readmission/complications.

Conclusion

Results of our study suggest that Medicare's NHC tool is not a useful predictor of 90-day costs, complications, or readmissions for SNFs within our health system.  相似文献   
40.
<正>Norepinephrine (NE; also known as noradrenaline) is the body's primary adrenergic neurotransmitter which belongs to the catecholamine family. Norepinephrine has pharmacologic effects on theα1 (Suita et al.,2015),α2 (Schwartz,1997),β1,β2 andβ3(Tsukada et al., 2003) adrenoceptors. In the brain, norepinephrine increases arousal and alertness, promotes vigilance, enhances formation and retrieval of memory, and focuses attention. It also increases restlessness and anxiety. In the remainder of the body,  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