全文获取类型
收费全文 | 4257篇 |
免费 | 332篇 |
国内免费 | 15篇 |
专业分类
耳鼻咽喉 | 38篇 |
儿科学 | 103篇 |
妇产科学 | 102篇 |
基础医学 | 701篇 |
口腔科学 | 340篇 |
临床医学 | 399篇 |
内科学 | 776篇 |
皮肤病学 | 57篇 |
神经病学 | 457篇 |
特种医学 | 118篇 |
外科学 | 435篇 |
综合类 | 25篇 |
一般理论 | 2篇 |
预防医学 | 411篇 |
眼科学 | 58篇 |
药学 | 267篇 |
中国医学 | 14篇 |
肿瘤学 | 301篇 |
出版年
2024年 | 9篇 |
2023年 | 62篇 |
2022年 | 93篇 |
2021年 | 202篇 |
2020年 | 134篇 |
2019年 | 162篇 |
2018年 | 162篇 |
2017年 | 125篇 |
2016年 | 151篇 |
2015年 | 134篇 |
2014年 | 178篇 |
2013年 | 210篇 |
2012年 | 326篇 |
2011年 | 393篇 |
2010年 | 195篇 |
2009年 | 155篇 |
2008年 | 277篇 |
2007年 | 232篇 |
2006年 | 232篇 |
2005年 | 207篇 |
2004年 | 150篇 |
2003年 | 123篇 |
2002年 | 111篇 |
2001年 | 38篇 |
2000年 | 32篇 |
1999年 | 46篇 |
1998年 | 26篇 |
1997年 | 20篇 |
1996年 | 14篇 |
1995年 | 16篇 |
1994年 | 17篇 |
1993年 | 13篇 |
1992年 | 30篇 |
1991年 | 26篇 |
1990年 | 46篇 |
1989年 | 37篇 |
1988年 | 23篇 |
1987年 | 37篇 |
1986年 | 30篇 |
1985年 | 21篇 |
1984年 | 9篇 |
1983年 | 16篇 |
1982年 | 7篇 |
1981年 | 16篇 |
1980年 | 7篇 |
1979年 | 17篇 |
1978年 | 7篇 |
1975年 | 4篇 |
1974年 | 9篇 |
1973年 | 7篇 |
排序方式: 共有4604条查询结果,搜索用时 15 毫秒
1.
2.
Emma J. Walker Noni E. MacDonald Nehal Islam Nicole Le Saux Karina A. Top Deshayne B. Fell 《Vaccine》2019,37(13):1725-1735
Objective
To systematically review literature on uptake and timeliness of diphtheria-tetanus-pertussis, measles-mumps-rubella, and/or polio-containing vaccines in infants who were born preterm, with a low birth weight, and/or with chronic health conditions that were diagnosed within the first 6?months of life.Methods
Using a standardized search strategy developed by a medical librarian, records were extracted from MEDLINE, Embase, Database of Abstracts of Reviews of Effects, and CINAHL up to May 8, 2018.Results
Out of the 1997 records that were screened, we identified 21 studies that met inclusion criteria. Eleven studies assessed vaccine coverage and/or timeliness in preterm infants, 6 in low birth weight infants, and 7 in children with chronic health conditions. Estimates of coverage in these populations were highly variable, ranging from 40% to 100% across the vaccines and population groups.Conclusions
There is a lack of studies reporting coverage and timeliness of routine immunizations in special populations of children.Policy implications
Our review suggests a need for improved surveillance of immunization status in special populations of infants, as well as a need for standardization of reporting practices. 相似文献3.
4.
Gary E. Stapleton Benjamin W. Eidem Ricardo H. Pignatelli Karina M. Carlson Charles E. Mullins Ronald G. Grifka 《Congenital heart disease》2006,1(3):116-119
Background. A persistent patent ductus arteriosus (PDA) may delay closure of a coexisting atrial septal defect (ASD) due to volume loading and enlargement of the left atrium. The purpose of this study was to investigate the natural history of ASD size in patients with a PDA following transcatheter PDA occlusion. Methods. All patients with an ASD and a PDA who underwent transcatheter PDA occlusion at Texas Children’s Hospital were identified. Patients with ASD diameter <3 mm, or additional cardiac defects were excluded. Eight patients (7 females) with small‐ to moderate‐sized ASDs and a PDA were identified. Patient demographics, echocardiographic data, and cardiac catheterization data were recorded. Data were analyzed by 1‐tailed t‐test. Results. Following PDA occlusion, ASD diameter decreased in 6 of 8 patients by a mean of 3.8 mm (±2.3 mm), including 2 that closed. The median duration of follow‐up was 689 days. One ASD remained unchanged and 1 increased in size. The mean maximum ASD diameter decreased from 6.4 mm (±2.2 mm) to 3.9 mm (±3.4 mm) (P = .03). Two patients underwent subsequent transcatheter ASD occlusion. Conclusion. Following transcatheter PDA occlusion, small‐ to moderate‐sized ASDs have significant probability to decrease in size, and possibly close. In infants and children, we recommend transcatheter PDA occlusion, and serial follow‐up of the size of the ASD. This will allow many small‐ to moderate‐sized ASDs to either close, or become smaller, obviating the need for future intervention. 相似文献
5.
Jakobsen Dodt Meyer Katzenstein Gerstoft & Skinhøj 《Scandinavian journal of immunology》1998,47(6):591-595
The purpose of the study was to investigate potential associations between tumour necrosis factor (TNF), soluble TNF receptors (sTNF-Rs), immunoglobulin (Ig)G subclasses and development of cytomegalovirus (CMV) disease amongst human immunodeficiency virus (HIV)-1 patients. We enrolled HIV-1 patients with CD4 counts less than 100/μl in a prospective study and followed them over 1 year for development of CMV disease. Concentrations of TNF, sTNF-RI, sTNF-RII and IgG subclass reactivities were measured by ELISA; levels of CMV pp65 antigenaemia were determined as numbers of pp65 expressing cells/100 000 cells and were measured by staining of leucocytes; and HIV-1 RNA loads were measured by polymerase chain reaction (PCR). Eighteen patients studied with CMV disease had higher levels of sTNF-RI than 18 similar patients without CMV disease. Concentrations of sTNF-RI correlated with levels of CMV antigenaemia in blood samples collected before the development of CMV disease. Patients with CMV disease had lower levels of IgG1 reactivities to CMV than patients without CMV disease. We conclude that increased levels of sTNF-RI and decreased IgG1 reactivities are associated with an increased risk of development of CMV disease among HIV-1 patients. 相似文献
6.
Karina D. TORRALBA Dorothy JOHNSON Francisco P. QUISMORIO 《International journal of rheumatic diseases》2006,9(3):294-297
A 66‐year‐old woman developed firm, painless, slowly growing nodular masses over her elbows, fingers, toes, and left hip over four years. Aspiration of the elbow mass revealed a white chalky material that was shown to be carbonate apatite on infrared spectroscopy and energy dispersive X‐ray spectroscopy. We discuss the classification of tumoral calcinosis and the nature of the calcium deposits. Tumoral calcinosis should be differentiated from tophaceous gout and calcium pyrophosphate dihydrate crystal deposition disease. Polarizing light microscopy and crystal analysis by X‐ray and infrared spectroscopy, electron or X‐ray diffraction will confirm the diagnosis. Secondary causes of tumoral calcinosis should also be excluded. 相似文献
7.
Adenosine instead of supranormal potassium in cardioplegic solution improves cardioprotection. 总被引:1,自引:0,他引:1
?yvind Jakobsen Stig Muller Erling Aarsaether Tor Steensrud Dag G S?rlie 《European journal of cardio-thoracic surgery》2007,32(3):493-500
OBJECTIVE: To determine whether adenosine instead of supranormal potassium in cold crystalloid cardioplegia gives satisfactory cardiac arrest and improved cardioprotection. Cold crystalloid cardioplegia with adenosine, procaine and magnesium (A) was compared with standard cold crystalloid hyperkalemic cardioplegia (K). METHODS: Sixteen pigs were randomized to receive either cold K (n=8) or A (n=8), where hyperkalemia was substituted with 1.2 mM adenosine. The cold (6 degrees C) cardioplegia was given intermittently and antegradely, with an aortic cross-clamp time of 1 h. Hemodynamic data was continuously measured and pressure-volume conductance catheters were used to determine global left ventricular systolic and diastolic function. Coronary flow and O2 content differences allowed determination of left ventricular energetics. Blood samples, and left ventricular microdialysis were used to measure parameters of ischemia. Measurements were done at 1 and 2 h after cross-clamp release. RESULTS: Mean arterial pressure was reduced with 55 mmHg (standard deviation, SD: 19) in the K group versus 30 mmHg (SD: 14) in the A group 2 h after cross-clamp release (p=0.030). Left ventricular contractility expressed as slope of the preload recruitable stroke work index (Mw) was reduced to 53% (SD: 14) in the K group versus 78% (SD: 23) in the A group 2h after cross-clamp release (p=0.046). Reduction of maximum of first derivate of pressure with respect to time (dP/dtmax) was 804 mmHg/s (SD: 189) in the K group versus 538 mmHg/s (SD: 184) in the A group (p=0.033). The slope of the myocardial oxygen consumption-pressure volume area was at 2 h reperfusion increased from 1.37 (SD: 0.64) to 2.86 (SD: 1.27) in the K group, whereas no shift was detected in the A group (p=0.019). Cardiac troponin T measured in the coronary sinus 1 h after cross-clamp release was 1.25 microg/l (SD: 0.64) in the K group versus 0.73 microg/l (SD: 0.31) in the A group (p=0.046). CONCLUSION: Adenosine instead of supranormal potassium in cold crystalloid cardioplegia gives satisfactory cardiac arrest, improves post cardioplegic left ventricular systolic function and efficiency, and attenuates myocardial cell damage. 相似文献
8.
9.
10.
Annals of Behavioral Medicine - 相似文献