全文获取类型
收费全文 | 41936篇 |
免费 | 2771篇 |
国内免费 | 542篇 |
专业分类
耳鼻咽喉 | 744篇 |
儿科学 | 683篇 |
妇产科学 | 637篇 |
基础医学 | 7023篇 |
口腔科学 | 620篇 |
临床医学 | 3429篇 |
内科学 | 8686篇 |
皮肤病学 | 1460篇 |
神经病学 | 3482篇 |
特种医学 | 2266篇 |
外科学 | 5559篇 |
综合类 | 228篇 |
一般理论 | 11篇 |
预防医学 | 1635篇 |
眼科学 | 1078篇 |
药学 | 3673篇 |
中国医学 | 513篇 |
肿瘤学 | 3522篇 |
出版年
2023年 | 315篇 |
2022年 | 903篇 |
2021年 | 1456篇 |
2020年 | 790篇 |
2019年 | 1059篇 |
2018年 | 1244篇 |
2017年 | 1004篇 |
2016年 | 1493篇 |
2015年 | 2000篇 |
2014年 | 2303篇 |
2013年 | 2585篇 |
2012年 | 3843篇 |
2011年 | 3645篇 |
2010年 | 2216篇 |
2009年 | 1822篇 |
2008年 | 2657篇 |
2007年 | 2397篇 |
2006年 | 2187篇 |
2005年 | 1996篇 |
2004年 | 1690篇 |
2003年 | 1485篇 |
2002年 | 1323篇 |
2001年 | 677篇 |
2000年 | 664篇 |
1999年 | 532篇 |
1998年 | 270篇 |
1997年 | 225篇 |
1996年 | 179篇 |
1995年 | 148篇 |
1994年 | 117篇 |
1993年 | 114篇 |
1992年 | 168篇 |
1991年 | 188篇 |
1990年 | 144篇 |
1989年 | 149篇 |
1988年 | 148篇 |
1987年 | 118篇 |
1986年 | 102篇 |
1985年 | 90篇 |
1984年 | 69篇 |
1983年 | 81篇 |
1982年 | 49篇 |
1981年 | 39篇 |
1980年 | 52篇 |
1979年 | 71篇 |
1978年 | 53篇 |
1977年 | 52篇 |
1976年 | 34篇 |
1973年 | 35篇 |
1972年 | 31篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
In this paper, we introduce a new type of troubled-cell indicator to improve
hybrid weighted essentially non-oscillatory (WENO) schemes for solving the hyperbolic conservation laws. The hybrid WENO schemes selectively adopt the high-order
linear upwind scheme or the WENO scheme to avoid the local characteristic decompositions and calculations of the nonlinear weights in smooth regions. Therefore,
they can reduce computational cost while maintaining non-oscillatory properties in
non-smooth regions. Reliable troubled-cell indicators are essential for efficient hybrid
WENO methods. Most of troubled-cell indicators require proper parameters to detect
discontinuities precisely, but it is very difficult to determine the parameters automatically. We develop a new troubled-cell indicator derived from the mean value theorem
that does not require any variable parameters. Additionally, we investigate the characteristics of indicator variable; one of the conserved properties or the entropy is considered as indicator variable. Detailed numerical tests for 1D and 2D Euler equations are
conducted to demonstrate the performance of the proposed indicator. The results with
the proposed troubled-cell indicator are in good agreement with pure WENO schemes.
Also the new indicator has advantages in the computational cost compared with the
other indicators. 相似文献
3.
Kun‐Yong Sung Seungkoo Lee Yeonjin Jeong Sang‐Yeul Lee 《The Australasian journal of dermatology》2021,62(1):60-63
A classic pilomatricoma, which usually presents with an asymptomatic, solitary, firm, subcutaneous nodule in the head, neck, or extremities of the paediatric population, is easily diagnosed based on its characteristic clinical and histopathological features. However, its variants often pose particular diagnostic challenges to clinicians due to their rarity and diverse clinicopathological features. We present a new pseudocystic variant, manifesting as solid lesions floating in a fluid‐filled sac. 相似文献
4.
Maxime Lafond Shin Yoshizawa Shin‐ichiro Umemura 《Journal of ultrasound in medicine》2019,38(3):567-580
Sonodynamic therapy (SDT) consists of the synergetic interaction between ultrasound and a chemical agent. In SDT, the cytotoxicity is triggered by ultrasonic stimuli, notably through cavitation. The unique features of SDT are relevant in the clinical context more than ever: the need for efficacy, accuracy, and safety while being noninvasive and preserving the patient's quality of life. However, despite the promising results of this technique, only a few clinical reports describe the use of SDT. The objective of this article is to provide an extensive overview of the clinical and preclinical research conducted in vivo on SDT, to identify the limitations, and to detail the developed strategies to overcome them. 相似文献
5.
6.
Cheong-Il Shin Sang Joon Park Ji-Hyun Kim Yeonyee Elizabeth Yoon Eun-Ah Park Bon-Kwon Koo Whal Lee 《Korean journal of radiology》2021,22(5):688
ObjectiveTo compare the lumen parameters measured by the location-adaptive threshold method (LATM), in which the inter- and intra-scan attenuation variabilities of coronary computed tomographic angiography (CCTA) were corrected, and the scan-adaptive threshold method (SATM), in which only the inter-scan variability was corrected, with the reference standard measurement by intravascular ultrasonography (IVUS).Materials and MethodsThe Hounsfield unit (HU) values of whole voxels and the centerline in each of the cross-sections of the 22 target coronary artery segments were obtained from 15 patients between March 2009 and June 2010, in addition to the corresponding voxel size. Lumen volume was calculated mathematically as the voxel volume multiplied by the number of voxels with HU within a given range, defined as the lumen for each method, and compared with the IVUS-derived reference standard. Subgroup analysis of the lumen area was performed to investigate the effect of lumen size on the studied methods. Bland-Altman plots were used to evaluate the agreement between the measurements.ResultsLumen volumes measured by SATM was significantly smaller than that measured by IVUS (mean difference, 14.6 mm3; 95% confidence interval [CI], 4.9–24.3 mm3); the lumen volumes measured by LATM and IVUS were not significantly different (mean difference, −0.7 mm3; 95% CI, −9.1–7.7 mm3). The lumen area measured by SATM was significantly smaller than that measured by LATM in the smaller lumen area group (mean of difference, 1.07 mm2; 95% CI, 0.89–1.25 mm2) but not in the larger lumen area group (mean of difference, −0.07 mm2; 95% CI, −0.22–0.08 mm2). In the smaller lumen group, the mean difference was lower in the Bland-Altman plot of IVUS and LATM (0.46 mm2; 95% CI, 0.27–0.65 mm2) than in that of IVUS and SATM (1.53 mm2; 95% CI, 1.27–1.79 mm2).ConclusionSATM underestimated the lumen parameters for computed lumen segmentation in CCTA, and this may be overcome by using LATM. 相似文献
7.
T.-Y. Huang Y.-J. Hsia M.-Y. Sung Y.-T. Wu P.-C. Hsu 《International journal of oral and maxillofacial surgery》2021,50(8):1100-1106
Zygomatic implant treatment is widely applied for severe maxillary atrophy to help rehabilitate the maxillary dentition. This retrospective study was performed to evaluate the actual radiographic bone–implant contact (rBIC) lengths of zygomatic implants. The records of 28 patients who underwent zygomatic implant surgery and subsequent follow-up examinations between August 2013 and September 2018 in the Department of Oral and Maxillofacial Surgery, Taipei Tzu Chi Hospital were reviewed. The surgeries were performed by a single surgeon using the same treatment protocol. All patients had a computed tomography scan at 1 year after the surgery. Using three-dimensional imaging software, an investigator measured the rBIC lengths of 66 implants and documented their clinical status. The implant survival rate was 100%. The mean rBIC length was significantly longer in male patients than in female patients (20.80 ± 5.88 mm versus 17.79 ± 6.34 mm; P = 0.028). The mean rBIC length of double zygomatic implants was significantly longer when compared to that of single implants (21.11 ± 6.23 mm versus 17.75 ± 5.85 mm; P = 0.027). This article is novel in reporting the exact rBIC lengths of zygomatic implants in a clinical setting. The results showed that zygomatic implants are a viable treatment modality for full-mouth rehabilitation. 相似文献
8.
9.