全文获取类型
收费全文 | 148014篇 |
免费 | 10278篇 |
国内免费 | 475篇 |
专业分类
耳鼻咽喉 | 1917篇 |
儿科学 | 3965篇 |
妇产科学 | 3164篇 |
基础医学 | 18276篇 |
口腔科学 | 2852篇 |
临床医学 | 14757篇 |
内科学 | 31914篇 |
皮肤病学 | 1902篇 |
神经病学 | 13255篇 |
特种医学 | 5263篇 |
外国民族医学 | 4篇 |
外科学 | 24624篇 |
综合类 | 1888篇 |
现状与发展 | 1篇 |
一般理论 | 122篇 |
预防医学 | 11049篇 |
眼科学 | 3458篇 |
药学 | 9350篇 |
中国医学 | 187篇 |
肿瘤学 | 10819篇 |
出版年
2023年 | 569篇 |
2022年 | 831篇 |
2021年 | 2707篇 |
2020年 | 1482篇 |
2019年 | 2635篇 |
2018年 | 3154篇 |
2017年 | 2326篇 |
2016年 | 2506篇 |
2015年 | 2970篇 |
2014年 | 4472篇 |
2013年 | 6596篇 |
2012年 | 9782篇 |
2011年 | 10199篇 |
2010年 | 5733篇 |
2009年 | 5143篇 |
2008年 | 9421篇 |
2007年 | 10242篇 |
2006年 | 9954篇 |
2005年 | 9973篇 |
2004年 | 9711篇 |
2003年 | 9097篇 |
2002年 | 8856篇 |
2001年 | 1225篇 |
2000年 | 850篇 |
1999年 | 1207篇 |
1998年 | 1843篇 |
1997年 | 1594篇 |
1996年 | 1314篇 |
1995年 | 1313篇 |
1994年 | 1167篇 |
1993年 | 1012篇 |
1992年 | 811篇 |
1991年 | 737篇 |
1990年 | 665篇 |
1989年 | 654篇 |
1988年 | 637篇 |
1987年 | 628篇 |
1986年 | 614篇 |
1985年 | 670篇 |
1984年 | 898篇 |
1983年 | 944篇 |
1982年 | 1188篇 |
1981年 | 1101篇 |
1980年 | 1000篇 |
1979年 | 555篇 |
1978年 | 620篇 |
1977年 | 661篇 |
1976年 | 558篇 |
1975年 | 477篇 |
1974年 | 397篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Jeffrey J. Silbiger 《Echocardiography (Mount Kisco, N.Y.)》2019,36(5):954-957
Secondary tricuspid regurgitation (TR) caused by right ventricular enlargement in the setting of left heart disease/pulmonary hypertension has been well described. In contrast, that associated with right atrial enlargement—atrial functional TR (AF‐TR)—remains largely underappreciated. AF‐TR most often occurs in the setting of lone atrial fibrillation, although it is also seen in its absence (idiopathic AF‐TR). Several recent studies have found that the prevalence, hemodynamic significance, and prognosis of AF‐TR are not inconsequential, suggesting increased physician awareness of this novel clinical entity is warranted. This article discusses the pathogenesis, echocardiographic findings, and treatment of this underappreciated cause of secondary TR. 相似文献
4.
5.
6.
Elizabeth D. Krebs Robert B. Hawkins J. Hunter Mehaffey Clifford E. Fonner Alan M. Speir Mohammed A. Quader Jeffrey B. Rich Leora T. Yarboro Nicholas R. Teman Gorav Ailawadi 《The Journal of thoracic and cardiovascular surgery》2019,157(4):1533-1542.e2
Objectives
Expedient extubation after cardiac surgery has been associated with improved outcomes, leading to postoperative extubation frequently during overnight hours. However, recent evidence in a mixed medical-surgical intensive care unit population demonstrated worse outcomes with overnight extubation. This study investigated the impact of overnight extubation in a statewide, multicenter Society of Thoracic Surgeons database.Methods
Records from 39,812 patients undergoing coronary artery bypass grafting or valve operations (2008-2016) and extubated within 24 hours were stratified according to extubation time between 06:00 and 18:00 (day) or between 18:00 and 6:00 (overnight). Outcomes including reintubation, mortality, and composite morbidity-mortality were evaluated using hierarchical regression models adjusted for Society of Thoracic Surgeons predictive risk scores. To further analyze extubation during the night, a subanalysis stratified patients into 3 groups: 06:00 to 18:00, 18:00 to 24:00, and 24:00 to 06:00.Results
A total of 20,758 patients were extubated overnight (52.1%) and were slightly older (median age 66 vs 65 years, P < .001) with a longer duration of ventilation (4 vs 7 hours, P < .001). Day and overnight extubation were associated with equivalent operative mortality (1.7% vs 1.7%, P = .880), reintubation (3.7% vs 3.4%, P = .141), and composite morbidity-mortality (8.2% vs 8.0%, P = .314). After risk adjustment, overnight extubation was not associated with any difference in reintubation, mortality, or composite morbidity-mortality. On subanalysis, those extubated between 24:00 and 06:00 exhibited increased composite morbidity-mortality (odds ratio, 1.18; P = .001) but no difference in reintubation or mortality.Conclusions
Extubation overnight was not associated with increased mortality or reintubation. These results suggest that in the appropriate clinical setting, it is safe to routinely extubate cardiac surgery patients overnight. 相似文献7.
Whitney S. Brandt Wanpu Yan Jian Zhou Kay See Tan Joseph Montecalvo Bernard J. Park Prasad S. Adusumilli James Huang Matthew J. Bott Valerie W. Rusch Daniela Molena William D. Travis Mark G. Kris Jamie E. Chaft David R. Jones 《The Journal of thoracic and cardiovascular surgery》2019,157(2):743-753.e3
Objective
Comparative survival between neoadjuvant chemotherapy and adjuvant chemotherapy for patients with cT2-4N0-1M0 non–small cell lung cancer has not been extensively studied.Methods
Patients with cT2-4N0-1M0 non–small cell lung cancer who received platinum-based chemotherapy were retrospectively identified. Exclusion criteria included stage IV disease, induction radiotherapy, and targeted therapy. The primary end point was disease-free survival. Secondary end points were overall survival, chemotherapy tolerance, and ability of Response Evaluation Criteria In Solid Tumors response to predict survival. Survival was estimated using the Kaplan–Meier method, compared using the log-rank test and Cox proportional hazards models, and stratified using matched pairs after propensity score matching.Results
In total, 330 patients met the inclusion criteria (n = 92/group after propensity-score matching; median follow-up, 42 months). Five-year disease-free survival was 49% (95% confidence interval, 39-61) for neoadjuvant chemotherapy versus 48% (95% confidence interval, 38-61) for adjuvant chemotherapy (P = .70). On multivariable analysis, disease-free survival was not associated with neoadjuvant chemotherapy or adjuvant chemotherapy (hazard ratio, 1.1; 95% confidence interval, 0.64-1.90; P = .737), nor was overall survival (hazard ratio, 1.21; 95% confidence interval, 0.63-2.30; P = .572). The neoadjuvant chemotherapy group was more likely to receive full doses and cycles of chemotherapy (P = .014/0.005) and had fewer grade 3 or greater toxicities (P = .001). Response Evaluation Criteria In Solid Tumors response to neoadjuvant chemotherapy was associated with disease-free survival (P = .035); 15% of patients receiving neoadjuvant chemotherapy (14/92) had a major pathologic response.Conclusions
Timing of chemotherapy, before or after surgery, is not associated with an improvement in overall or disease-free survival among patients with cT2-4N0-1M0 non–small cell lung cancer who undergo complete surgical resection. 相似文献8.
Alexandra Elliott Laura Schoenlaub Danielle Freches William Mitchell Guoquan Zhang 《Infection and immunity》2015,83(8):3104-3113
Coxiella burnetii is an obligate intracellular Gram-negative bacterium that causes the zoonotic disease Q fever. Although Q fever is mainly transmitted by aerosol infection, study of the immune responses in the lung following pulmonary C. burnetii infection is lacking. Neutrophils are considered the first immune cell to migrate into the lung and play an important role in host defense against aerosol infection with microbial pathogens. However, the role of neutrophils in the host defense against C. burnetii infection remains unclear. To determine the role of neutrophils in protective immunity against C. burnetii infection, the RB6-8C5 antibody was used to deplete neutrophils in mice before intranasal infection with C. burnetii. The results indicated that neutrophil-depleted mice developed more severe disease than their wild-type counterparts, suggesting that neutrophils play an important role in host defense against C. burnetii pulmonary infection. We also found that neither CXC chemokine receptor 2 (CXCR2) nor interleukin-17 (IL-17) receptor (IL-17R) deficiency changed the severity of disease following intranasal C. burnetii challenge, suggesting that keratinocyte-derived chemokine and IL-17 may not play essential roles in the response to C. burnetii infection. However, significantly higher C. burnetii genome copy numbers were detected in the lungs of IL-1R−/− mice at 14 days postinfection. This indicates that IL-1 may be important for the clearance of C. burnetii from the lungs following intranasal infection. Our results also suggest that neutrophils are involved in protecting vaccinated mice from C. burnetii challenge-induced disease. This is the first study to demonstrate an important role for neutrophils in protective immunity against C. burnetii infection. 相似文献
9.
10.
Jeffrey Buenaflor Parker Sommerville Hang Qian Christine Luscombe 《Macromolecular chemistry and physics.》2020,221(2)
A comparative study involving bimetallic nickel catalysts designed from disubstituted N,N,N′,N′‐tetra(diphenylphosphanylmethyl)benzene diamine bridging ligands is reported. Catalyst behavior is explored in the Kumada catalyst‐transfer polymerization (KCTP) using poly(3‐hexylthiophene) (P3HT) as the model system. The success of a controlled polymerization is monitored by analyzing monomer conversion, degree of polymerization, end‐group identity, and molecular weight distribution. The characterization of P3HT obtained from KCTP initiated with the bimetallic catalysts shows chain‐growth behavior; however, the presence of Br/Br end‐groups and broader molecular weight distribution reveals a reduced controlled polymerization compared to the commonly employed Ni(dppp)Cl2. The observed increase in intermolecular chain transfer and termination processes in KCTP initiation with the bimetallic catalysts can be attributed to a weaker Ni(0)‐π‐aryl complex interaction, which is caused by increased steric crowding of the coordination sphere. 相似文献