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   65619篇
  免费   4601篇
  国内免费   1317篇
耳鼻咽喉   373篇
儿科学   1953篇
妇产科学   1194篇
基础医学   5453篇
口腔科学   1112篇
临床医学   8385篇
内科学   10667篇
皮肤病学   605篇
神经病学   2589篇
特种医学   2007篇
外国民族医学   2篇
外科学   6091篇
综合类   10532篇
现状与发展   2篇
预防医学   8353篇
眼科学   620篇
药学   6539篇
  54篇
中国医学   3334篇
肿瘤学   1672篇
  2023年   1182篇
  2022年   1981篇
  2021年   3135篇
  2020年   2836篇
  2019年   2460篇
  2018年   2484篇
  2017年   2113篇
  2016年   2133篇
  2015年   2134篇
  2014年   4597篇
  2013年   4508篇
  2012年   4012篇
  2011年   4317篇
  2010年   3427篇
  2009年   3185篇
  2008年   3041篇
  2007年   3018篇
  2006年   2579篇
  2005年   2216篇
  2004年   1849篇
  2003年   1600篇
  2002年   1258篇
  2001年   1170篇
  2000年   1022篇
  1999年   890篇
  1998年   728篇
  1997年   684篇
  1996年   577篇
  1995年   619篇
  1994年   576篇
  1993年   496篇
  1992年   463篇
  1991年   418篇
  1990年   367篇
  1989年   326篇
  1988年   324篇
  1987年   299篇
  1986年   224篇
  1985年   260篇
  1984年   304篇
  1983年   196篇
  1982年   219篇
  1981年   186篇
  1980年   174篇
  1979年   145篇
  1978年   137篇
  1977年   116篇
  1976年   87篇
  1975年   74篇
  1973年   89篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
ObjectivesThe reduction of postoperative acute kidney injury in patients undergoing cardiopulmonary bypass surgery using an oxygen delivery-guided perfusion strategy (oxygen delivery strategy) for cardiopulmonary bypass management compared with a fixed flow perfusion (conventional strategy) remains controversial. The purpose of this study was to determine whether a oxygen delivery strategy would reduce the incidence of postoperative acute kidney injury in patients undergoing cardiopulmonary bypass surgery.MethodsWe randomly enrolled 300 patients undergoing cardiopulmonary bypass surgery. Patients were randomly assigned to a oxygen delivery strategy (maintaining a oxygen delivery index value >300 mL/min/m2 through pump flow adjustments during cardiopulmonary bypass) or a conventional strategy (a target pump flow was determined on the basis of the body surface area). The primary end point was the development of acute kidney injury. Secondary end points were the red blood cell transfusion rate and number of red blood cell units, intubation time, postoperative length of stay in the intensive care unit and the hospital, predischarge estimated glomerular filtration rate, and hospital mortality.ResultsAcute kidney injury occurred in 20 patients (14.6%) receiving the oxygen delivery strategy and in 42 patients (30.4%) receiving the conventional strategy (relative risk, 0.48; 95% confidence interval, 0.30-0.77; P = .002). The secondary end points were not significantly different between strategies. In a prespecified subgroup analysis of patients who had nadir hematocrit less than 23% or body surface area less than 1.40 m2, the oxygen delivery strategy seemed to be superior to the conventional strategy and the existence of quantitative interactions was suggested.ConclusionsAn oxygen delivery strategy for cardiopulmonary bypass management was superior to a conventional strategy with respect to preventing the development of acute kidney injury.  相似文献   
42.
43.
目的分析重症肺炎并呼吸衰竭患儿接受早期持续气道正压通气(CPAP)治疗对血气指标及预后的影响。方法选取2019年2月至2020年6月本院收治的110例重症肺炎并呼吸衰竭患儿,按照组间基本资料具有可比性的原则分为对照组与实验组,各55例。对照组接受常规方案治疗,实验组接受早期持续CPAP治疗,比较两组血气指标改善情况以及患儿预后。结果治疗后,两组PaO2、PaCO2、SaO2均显著改善,且实验组改善程度明显优于对照组(P<0.05)。实验组临床病死率明显低于对照组(P<0.05)。两组并发症发生率比较差异无统计学意义。结论采用早期持续CPAP治疗重症肺炎并呼吸衰竭患儿效果显著,能明显改善血气指标和预后,具有临床推广价值。  相似文献   
44.
45.
ObjectiveTo investigate the association between type 1 diabetes mellitus (T1D) and type 2 diabetes mellitus (T2D) with risk of sudden cardiac arrest (SCA).MethodsIn a prospective community-based study of SCA from February 1, 2002, through November 30, 2019, we ascertained 2771 cases age 18 years of age or older and matched them to 8313 controls based on geography, age, sex, and race/ethnicity. We used logistic regression to evaluate the independent association between diabetes, T1D, T2D, and SCA.ResultsPatients had a mean age of 64.5±15.9 years, were 33.3% female and 23.9% non-White race. Overall, 36.7% (n=1016) of cases and 23.8% (n=1981) of controls had diabetes. Among individuals with diabetes, the proportion of T1D was 6.5% (n=66) among cases and 2.0% among controls (n=40). Diabetes was associated with 1.5-times higher odds of SCA. Compared with those without diabetes, the odds ratio and 95% CI for SCA was 4.36 (95% CI, 2.81 to 6.75; P<.001) in T1D and 1.45 (95% CI, 1.30 to 1.63; P<.001) in T2D after multivariable adjustment. Among those with diabetes, the odds of having SCA were 2.41 times higher in T1D than in T2D (95% CI, 1.53 to 3.80; P<.001). Cases of SCA with T1D were more likely to have an unwitnessed arrest, less likely to receive resuscitation, and less likely to survive compared with those with T2D.ConclusionType 1 diabetes was more strongly associated with SCA compared with T2D and had less favorable outcomes following resuscitation. Diabetes type could influence the approach to risk stratification and prevention of SCA.  相似文献   
46.
《Vaccine》2022,40(24):3320-3329
BackgroundCurrently, booster dose is needed after 2 doses of non-live COVID-19 vaccine. With limited resources and shortage of COVID-19 vaccines, intradermal(ID) administration might be a potential dose-sparing strategy.ObjectiveTo determine immunologic response and reactogenicity of ID ChAdOx1 nCoV-19 vaccine (AZD1222,Oxford/AstraZeneca) as a booster dose after completion of 2-dose CoronaVac(SV) in healthy adult.MethodsThis is a prospective cohort study of adult aged 18–59 years who received 2-dose SV at 14–35 days apart for more than 2 months. Participants received ID AZD1222 at fractional low dose(1×1010 viral particles,0.1 ml). Antibody responses were evaluated by surrogate virus neutralization test(sVNT) against delta variant and wild type, and anti-spike-receptor-binding-domain immunoglobulin G(anti-S-RBD IgG) at prior, day14, 28, 90, and 180 post booster. Solicited reactogenicity was collected for 7 days post-booster. Primary endpoint was the differences of sVNT against delta strain ≥ 80% inhibition at day14 and 90 compared with the parallel cohort study of 0.5-ml intramuscular(IM) route.ResultsFrom August2021, 100 adults with median age of 46 years(IQR 41–52) participated. Prior to booster, geometric mean(GM) of sVNT against delta strain was 22.4% inhibition(95 %CI 18.7–26.9) and of anti-S-RBD IgG was 109.3 BAU/ml(95.4–125.1). Post ID booster, GMs of sVNT against delta strain were 95.5% inhibition (95%CI 94.2–96.8) at day14, 73.1% inhibition (66.7–80.2) at day90, and 22.7% inhibition (14.9–34.6) at day180. The differences of proportion of participants achieving sVNT against delta strain ≥ 80% inhibition in ID recipients versus IM were + 4.2% (95 %CI -2.0to10.5) at day14, and ?37.3%(-54.2to-20.3) at day90. Anti-S-RBD IgG GMs were 2037.1 BAU/ml (95%CI 1770.9–2343.2) at day14 and 744.6 BAU/ml(650.1–852.9) at day90, respectively. Geometric mean ratios(GMRs) of anti-S-RBD IgG were 0.99(0.83–1.20) at day14, and 0.82(0.66–1.02) at day90. Only 18% reported feverish, compared with 37% of IM (p = 0.003). Common reactogenicity was erythema at injection site(53%) while 7% reported blister.ConclusionLow-dose ID AZD1222 booster enhanced lower neutralizing antibodies at 3 months compared with IM route. Less systemic reactogenicity occurred, but higher local reactogenicity.  相似文献   
47.
48.
49.
IntroductionThere is a growing interest in physical activity in relation to recovery after surgery. One important aspect of measuring recovery after surgical procedures is postoperative complications. The aim of this study was to determine if there is an association between the preoperative level of habitual physical activity and postoperative complications in patients undergoing elective surgery for colorectal cancer.Materials and methods115 patients scheduled for elective surgery due to colorectal cancer between February 2014 and September 2015 answered a questionnaire regarding physical activity and other baseline variables. Physical activity was assessed using the Saltin-Grimby physical activity level scale. Complications within 30 days after surgery were classified according to Clavien-Dindo, and the Comprehensive Complications Index (CCI) was calculated. Primary outcome was difference in CCI and key secondary outcome was risk for CCI ≥20.ResultsPhysically inactive individuals had a CCI that was 12 points higher than individuals with light activity (p = 0.002) and 17 points higher than regularly active individuals (p = 0.0004). Inactive individuals had a relative risk for a CCI ≥20 that was 65% higher than for individuals reporting light activity (95% confidence interval (CI) for relative risk (RR) = 1.1–2.5) and 338% higher than for regularly active individuals (95% CI for RR = 2.1–9.4).ConclusionSelf-assessed level of habitual physical activity before colorectal cancer surgery was associated with fewer postoperative complications measured with CCI, in a dose-response relationship.  相似文献   
50.
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