全文获取类型
收费全文 | 46908篇 |
免费 | 3606篇 |
国内免费 | 190篇 |
学科分类
医药卫生 | 50704篇 |
出版年
2023年 | 421篇 |
2022年 | 374篇 |
2021年 | 1706篇 |
2020年 | 1017篇 |
2019年 | 1345篇 |
2018年 | 1522篇 |
2017年 | 1025篇 |
2016年 | 1198篇 |
2015年 | 1379篇 |
2014年 | 1869篇 |
2013年 | 2177篇 |
2012年 | 3551篇 |
2011年 | 3501篇 |
2010年 | 1946篇 |
2009年 | 1724篇 |
2008年 | 2726篇 |
2007年 | 2786篇 |
2006年 | 2587篇 |
2005年 | 2404篇 |
2004年 | 2226篇 |
2003年 | 2030篇 |
2002年 | 1860篇 |
2001年 | 530篇 |
2000年 | 518篇 |
1999年 | 538篇 |
1998年 | 430篇 |
1997年 | 340篇 |
1996年 | 255篇 |
1995年 | 247篇 |
1994年 | 210篇 |
1993年 | 212篇 |
1992年 | 374篇 |
1991年 | 340篇 |
1990年 | 312篇 |
1989年 | 270篇 |
1988年 | 258篇 |
1987年 | 238篇 |
1986年 | 233篇 |
1985年 | 259篇 |
1984年 | 213篇 |
1983年 | 203篇 |
1982年 | 167篇 |
1981年 | 154篇 |
1980年 | 168篇 |
1979年 | 179篇 |
1978年 | 149篇 |
1977年 | 135篇 |
1976年 | 134篇 |
1974年 | 141篇 |
1973年 | 121篇 |
排序方式: 共有10000条查询结果,搜索用时 325 毫秒
991.
P. Elliott Miller Alexander Thomas Thomas J. Breen Fouad Chouairi Yukiko Kunitomo Faisal Aslam Abdulla A. Damluji Nandan S. Anavekar Joseph G. Murphy Sean van Diepen Gregory W. Barsness Joseph Brennan Jacob Jentzer 《The American journal of medicine》2021,134(5):653-661.e5
BackgroundCurrent cardiac intensive care unit (CICU) practice has seen an increase in patient complexity, including an increase in noncardiac organ failure, critical care therapies, and comorbidities. We sought to describe the changing epidemiology of noncardiac multimorbidity in the CICU population.MethodsWe analyzed consecutive unique patient admissions to 2 geographically distant tertiary care CICUs (n = 16,390). We assessed for the prevalence of 0, 1, 2, and ≥3 noncardiac comorbidities (diabetes, chronic lung, liver, and kidney disease, cancer, and stroke/transient ischemic attack) and their associations with hospital and postdischarge 1-year mortality using multivariable logistic regression.ResultsThe prevalence of 0, 1, 2, and ≥3 noncardiac comorbidities was 37.7%, 31.4%, 19.9%, and 11.0%, respectively. Increasing noncardiac comorbidities were associated with a stepwise increase in mortality, length of stay, noncardiac indications for ICU admission, and increased utilization of critical care therapies. After multivariable adjustment, compared with those without noncardiac comorbidities, there was an increased hospital mortality for patients with 1 (odds ratio [OR] 1.30; 95% confidence interval [CI], 1.10-1.54, P = .002), 2 (OR 1.47; 95% CI, 1.22-1.77, P < .001), and ≥3 (OR 1.79; 95% CI, 1.44-2.22, P < .001) noncardiac comorbidities. Similar trends for each additional noncardiac comorbidity were seen for postdischarge 1-year mortality (P < .001, all).ConclusionsIn 2 large contemporary CICU populations, we found that noncardiac multimorbidity was highly prevalent and a strong predictor of short- and long-term adverse clinical outcomes. Further study is needed to define the best care pathways for CICU patients with acute cardiac illness complicated by noncardiac multimorbidity. 相似文献
992.
Todd C. Lee Marnie Goodwin Wilson Alexander Lawandi Emily G. McDonald 《The American journal of medicine》2021,134(3):e184-e188
BackgroundUpper gastrointestinal bleeding is common among the critically ill. Recently, the Proton Pump Inhibitors (PPIs) vs. Histamine-2 Receptor Blockers for Ulcer Prophylaxis Therapy in the Intensive Care Unit (PEPTIC) trial suggested PPIs might increase mortality. We performed an updated meta-analysis to further inform discussion.MethodsWe leveraged 2 recent systematic reviews to identify randomized controlled trials directly comparing PPIs and H-2 Receptor Antagonists (H2RAs) for stress ulcer prophylaxis in critically ill patients and reporting mortality. We extracted mortality data from each study and meta-analyzed them with the PEPTIC trial using a random effects model.ResultsOf 28,559 total patients, 14,436 (50.5%) were allocated to PPI and 14,123 to H2RAs (49.5%). Compared to H2RAs, the pooled relative risk for mortality was 1.05 (95% confidence interval 1.00-1.10) with an estimated risk difference for mortality of 9 additional deaths per 1000 patients exposed to PPI (95% confidence interval 0-18); heterogeneity was low (I2 = 0%; P = 0.826).ConclusionsStress ulcer prophylaxis with PPIs likely increases mortality compared to H2RAs. Whether stress ulcer prophylaxis is beneficial in critical care remains open to further study. 相似文献
993.
994.
995.
996.
Luigi Villa Thilo Krüger Claudia Seikrit Anja S. Mühlfeld Uta Kunter Cornelius Werner Michael Kleines Maximilian Schulze-Hagen Michael Dreher Alexander Kersten Nikolaus Marx Jürgen Floege Thomas Rauen Gerald S. Braun 《Medicine》2021,100(10)
Chronic renal replacement therapy by either a kidney transplant (KTX) or hemodialysis (HD) predisposes patients to an increased risk for adverse outcomes of COVID-19. However, details on this interaction remain incomplete. To provide further characterization, we undertook a retrospective observational cohort analysis of the majority of the hemodialysis and renal transplant population affected by the first regional outbreak of severe acute respiratory distress syndrome coronavirus 2 (SARS-CoV-2) in Germany. In a region of 250,000 inhabitants we identified a total of 21 cases with SARS-CoV-2 among 100 KTX and 260 HD patients, that is, 7 KTX with COVID-19, 14 HD with COVID-19, and 3 HD with asymptomatic carrier status. As a first observation, KTX recipients exhibited trends for a higher mortality (43 vs 18%) and a higher proportion of acute respiratory distress syndrome (ARDS) (57 vs 27%) when compared to their HD counterparts. As a novel finding, development of ARDS was significantly associated with the time spent on previous renal replacement therapy (RRT), defined as the composite of dialysis time and time on the transplant (non-ARDS 4.3 vs ARDS 10.6 years, P = .016). Multivariate logistic regression analysis showed an OR of 1.7 per year of RRT. The association remained robust when analysis was confined to KTX patients (5.1 vs 13.2 years, P = .002) or when correlating the time spent on a renal transplant alone (P = .038). Similarly, longer RRT correlated with death vs survival (P = .0002). In conclusion our data suggest renal replacement vintage as a novel risk factor for COVID-19-associated ARDS and death. The findings should be validated by larger cohorts. 相似文献
997.
Adrie W. Bruijnzeel Jon C. Alexander Pablo D. Perez Rayna Bauzo-Rodriguez Gabrielle Hall Rachel Klausner Valerie Guerra Huadong Zeng Moe Igari Marcelo Febo 《The international journal of neuropsychopharmacology / official scientific journal of the Collegium Internationale Neuropsychopharmacologicum (CINP)》2015,18(2)
Background:
Acute nicotine administration potentiates brain reward function and enhances motor and cognitive function. These studies investigated which brain areas are being activated by a wide range of doses of nicotine, and if this is diminished by pretreatment with the nonselective nicotinic receptor antagonist mecamylamine.Methods:
Drug-induced changes in brain activity were assessed by measuring changes in the blood oxygen level dependent (BOLD) signal using an 11.1-Tesla magnetic resonance scanner. In the first experiment, nicotine naïve rats were mildly anesthetized and the effect of nicotine (0.03–0.6mg/kg) on the BOLD signal was investigated for 10min. In the second experiment, the effect of mecamylamine on nicotine-induced brain activity was investigated.Results:
A high dose of nicotine increased the BOLD signal in brain areas implicated in reward signaling, such as the nucleus accumbens shell and the prelimbic area. Nicotine also induced a dose-dependent increase in the BOLD signal in the striato-thalamo-orbitofrontal circuit, which plays a role in compulsive drug intake, and in the insular cortex, which contributes to nicotine craving and relapse. In addition, nicotine induced a large increase in the BOLD signal in motor and somatosensory cortices. Mecamylamine alone did not affect the BOLD signal in most brain areas, but induced a negative BOLD response in cortical areas, including insular, motor, and somatosensory cortices. Pretreatment with mecamylamine completely blocked the nicotine-induced increase in the BOLD signal.Conclusions:
These studies demonstrate that acute nicotine administration activates brain areas that play a role in reward signaling, compulsive behavior, and motor and cognitive function. 相似文献998.
999.
1000.