全文获取类型
收费全文 | 2839篇 |
免费 | 393篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 3篇 |
儿科学 | 105篇 |
妇产科学 | 40篇 |
基础医学 | 100篇 |
口腔科学 | 80篇 |
临床医学 | 136篇 |
内科学 | 326篇 |
皮肤病学 | 15篇 |
神经病学 | 82篇 |
特种医学 | 148篇 |
外科学 | 133篇 |
综合类 | 13篇 |
预防医学 | 1882篇 |
眼科学 | 8篇 |
药学 | 70篇 |
肿瘤学 | 97篇 |
出版年
2023年 | 33篇 |
2022年 | 52篇 |
2021年 | 28篇 |
2020年 | 92篇 |
2019年 | 28篇 |
2018年 | 98篇 |
2017年 | 102篇 |
2016年 | 101篇 |
2015年 | 94篇 |
2014年 | 93篇 |
2013年 | 167篇 |
2012年 | 44篇 |
2011年 | 39篇 |
2010年 | 115篇 |
2009年 | 134篇 |
2008年 | 73篇 |
2007年 | 75篇 |
2006年 | 83篇 |
2005年 | 59篇 |
2004年 | 47篇 |
2003年 | 35篇 |
2002年 | 89篇 |
2001年 | 91篇 |
2000年 | 59篇 |
1999年 | 143篇 |
1998年 | 158篇 |
1997年 | 196篇 |
1996年 | 208篇 |
1995年 | 132篇 |
1994年 | 55篇 |
1993年 | 124篇 |
1992年 | 29篇 |
1991年 | 19篇 |
1990年 | 21篇 |
1989年 | 35篇 |
1988年 | 35篇 |
1987年 | 27篇 |
1986年 | 31篇 |
1985年 | 25篇 |
1984年 | 16篇 |
1983年 | 17篇 |
1982年 | 17篇 |
1981年 | 15篇 |
1980年 | 11篇 |
1979年 | 9篇 |
1978年 | 9篇 |
1977年 | 9篇 |
1976年 | 18篇 |
1975年 | 7篇 |
1974年 | 6篇 |
排序方式: 共有3238条查询结果,搜索用时 15 毫秒
81.
Apoptosis is an important process in the development and function of the central nervous system (CNS). To study the role of DNA fragmentation factor 45 (DFF45/ICAD) in CNS function, we previously generated DFF45 knockout mice. We found that whereas they exhibit apparently normal CNS development, DFF45 knockout mice exhibit an increased number of granule cells in the dentate gyrus and enhanced spatial learning and memory compared to wild-type mice in a Morris water maze test. In this study, we examined the performance of the DFF45 knockout mice in a novel object recognition task to measure short-term nonspatial memory that is believed to depend on the hippocampal formation. Both wild-type and DFF45 knockout mice exhibited novel object recognition 1 h posttraining. However, whereas wild-type mice no longer did so, DFF45 knockout mice were still able to differentiate the novel versus the familiar object 3 h posttraining. The longer memory retention in DFF45 knockout mice did not last up to 24 h as neither wild-type nor DFF45 knockout mice demonstrated novel object recognition 24 h posttraining. These results suggest that a lack of DFF45 facilitates hippocampus-dependent nonspatial memory, as well as hippocampus-dependent spatial memory. 相似文献
82.
83.
Breast cancer detection: one versus two views 总被引:2,自引:0,他引:2
Mammographic examinations of 169 patients with 172 biopsy-proved carcinomas, and of 194 healthy subjects, were interpreted independently and retrospectively by three experienced mammographers, initially as single-view oblique examinations and 6 months later as two-view oblique-cephalocaudal examinations. For the single-view examinations of the cancer patients, 67% of the cancers were correctly recommended for biopsy, additional views were requested for 23%, and a "negative" interpretation was made for 10%. For the single-view examinations of healthy subjects, biopsy was recommended for 7% and additional views were recommended for 32%. For the two-view examinations of women with cancer, 80% of the cancers were correctly recommended for biopsy, additional views were requested for 4%, and a "negative" interpretation was made for 16%. For two-view examinations of healthy subjects, biopsy was recommended for 7% and additional views were requested for only 5%. The authors conclude that single-view screening should not be performed, because it would lead to an excessive number of "call-back" examinations of healthy patients, producing additional cost and anxiety that would outweigh any theoretical benefit. 相似文献
84.
85.
86.
Dane Christina Daoud MD Elena M. S. Cartagena MD MSc Katherine J. P. Schwenger RD PhD Nicha Somlaw MD Leah Gramlich MD Scott Whittaker MD David Armstrong MD Brian Jurewitsch PharmD Matreyi Raman MD Donald R. Duerksen MD James D. McHattie MD Johane P. Allard MD 《JPEN. Journal of parenteral and enteral nutrition》2022,46(2):348-356
87.
Specific nutrition and metabolic characteristics of critically ill patients with persistent COVID-19
88.
Thainá Gattermann Pereira RD MS Júlia Lima RD Flávia Moraes Silva RD PhD 《JPEN. Journal of parenteral and enteral nutrition》2022,46(5):977-996
Impaired nutrition status is recognized as a risk factor for worse clinical outcomes in patients with chronic obstructive pulmonary disease (COPD). The aims of this study were to investigate how undernutrition is diagnosed, its prevalence, and whether there is an association between this condition and clinical outcomes in patients with COPD. The search for this systematic review of observational studies (PROSPERO: CRD42020191888) was performed in the PubMed, Embase, and Scopus databases, with no date or language restrictions. The studies had to report data on the diagnosis of undernutrition and its association with mortality, exacerbation, length of hospital stay, or quality of life in adult patients with COPD. A meta-analysis with a random-effects model was performed to combine data. Forty-nine studies were included (20 of them classified as having a low risk of bias), and the most common diagnostic method of undernutrition was body mass index (BMI) (n = 36). The pooled prevalence of undernutrition was equal to 20% (95% CI, 0.15–0.25; I² = 100%), and it was associated with mortality (risk ratio = 1.97; 95% CI, 1.55–2.50; I² = 98%), exacerbation (risk ratio = 1.73; 95% CI, 1.03–2.91; I² = 96%), and poorer quality of life (mean difference = 8.25; 95% CI, 5.40–11.10; I² = 79%). For all outcomes, the certainty of evidence was very low. In conclusion, undernutrition is prevalent and is associated with poorer outcomes in patients with COPD. However, undernutrition is mainly diagnosed by BMI, which underreports its prevalence, and the certainty of the evidence is very low. 相似文献
89.