全文获取类型
收费全文 | 317682篇 |
免费 | 14992篇 |
国内免费 | 10887篇 |
专业分类
耳鼻咽喉 | 2281篇 |
儿科学 | 8051篇 |
妇产科学 | 4571篇 |
基础医学 | 33532篇 |
口腔科学 | 4251篇 |
临床医学 | 31969篇 |
内科学 | 52332篇 |
皮肤病学 | 2050篇 |
神经病学 | 24119篇 |
特种医学 | 14136篇 |
外国民族医学 | 105篇 |
外科学 | 42863篇 |
综合类 | 27368篇 |
现状与发展 | 49篇 |
一般理论 | 8篇 |
预防医学 | 27240篇 |
眼科学 | 6994篇 |
药学 | 24622篇 |
104篇 | |
中国医学 | 8573篇 |
肿瘤学 | 28343篇 |
出版年
2024年 | 548篇 |
2023年 | 2655篇 |
2022年 | 6265篇 |
2021年 | 7694篇 |
2020年 | 5815篇 |
2019年 | 5054篇 |
2018年 | 26581篇 |
2017年 | 21784篇 |
2016年 | 23539篇 |
2015年 | 7672篇 |
2014年 | 9043篇 |
2013年 | 7774篇 |
2012年 | 17526篇 |
2011年 | 32555篇 |
2010年 | 25597篇 |
2009年 | 16827篇 |
2008年 | 26501篇 |
2007年 | 28876篇 |
2006年 | 7832篇 |
2005年 | 9526篇 |
2004年 | 7957篇 |
2003年 | 8622篇 |
2002年 | 6157篇 |
2001年 | 3492篇 |
2000年 | 3900篇 |
1999年 | 4199篇 |
1998年 | 2774篇 |
1997年 | 2685篇 |
1996年 | 1952篇 |
1995年 | 1756篇 |
1994年 | 1589篇 |
1993年 | 1035篇 |
1992年 | 1271篇 |
1991年 | 1088篇 |
1990年 | 1038篇 |
1989年 | 857篇 |
1988年 | 752篇 |
1987年 | 624篇 |
1986年 | 473篇 |
1985年 | 390篇 |
1984年 | 205篇 |
1983年 | 154篇 |
1982年 | 110篇 |
1981年 | 84篇 |
1980年 | 86篇 |
1979年 | 74篇 |
1938年 | 61篇 |
1934年 | 34篇 |
1932年 | 57篇 |
1930年 | 47篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
Seyed Mehdi BagheriMofidi Majid Pouladian Seyed Behnamedin Jameie Ali Abbaspour Tehrani-Fard 《Australasian physical & engineering sciences in medicine / supported by the Australasian College of Physical Scientists in Medicine and the Australasian Association of Physical Sciences in Medicine》2016,39(3):717-726
Magnetic field generated by neuronal activity could alter magnetic resonance imaging (MRI) signals but detection of such signal is under debate. Previous researches proposed that magnitude signal change is below current detectable level, but phase signal change (PSC) may be measurable with current MRI systems. Optimal imaging parameters like echo time, voxel size and external field direction, could increase the probability of detection of this small signal change. We simulate a voxel of cortical column to determine effect of such parameters on PSC signal. We extended a laminar network model for somatosensory cortex to find neuronal current in each segment of pyramidal neurons (PN). 60,000 PNs of simulated network were positioned randomly in a voxel. Biot–savart law applied to calculate neuronal magnetic field and additional phase. The procedure repeated for eleven neuronal arrangements in the voxel. PSC signal variation with the echo time and voxel size was assessed. The simulated results show that PSC signal increases with echo time, especially 100/80 ms after stimulus for gradient echo/spin echo sequence. It can be up to 0.1 mrad for echo time = 175 ms and voxel size = 1.48 × 1.48 × 2.18 mm3. With echo time less than 25 ms after stimulus, it was just acquired effects of physiological noise on PSC signal. The absolute value of the signal increased with decrease of voxel size, but its components had complex variation. External field orthogonal to local surface of cortex maximizes the signal. Expected PSC signal for tactile detection in the somatosensory cortex increase with echo time and have no oscillation. 相似文献
3.
4.
5.
6.
儿童哮喘的发病率逐年上升.基于卫生假说,抗生素使用可能减少了微生物暴露,从而增加了过敏性疾病发生的风险.近十年来,就早期抗生素暴露与儿童哮喘的关系进行的大量的流行病学调查的结果并不一致.大多数回顾性研究发现正相关联系,但前瞻性研究未发现联系或联系强度较弱.逆向因果和指示混淆可部分解释两者的关系,但也难以否定因果关系的存在. 相似文献
7.
Peng‐fei Lei Shi‐long Su Ling‐yu Kong Cheng‐gong Wang Da Zhong Yi‐he Hu 《Orthopaedic Surgery》2019,11(5):914-920
Three‐dimensional (3D) printing technology, virtual reality, and augmented reality technology have been used to help surgeons to complete complex total hip arthroplasty, while their respective shortcomings limit their further application. With the development of technology, mixed reality (MR) technology has been applied to improve the success rate of complicated hip arthroplasty because of its unique advantages. We presented a case of a 59‐year‐old man with an intertrochanteric fracture in the left femur, who had received a prior left hip fusion. After admission to our hospital, a left total hip arthroplasty was performed on the patient using a combination of MR technology and 3D printing technology. Before surgery, 3D reconstruction of a certain bony landmark exposed in the surgical area was first performed. Then a veneer part was designed according to the bony landmark and connected to a reference registration landmark outside the body through a connecting rod. After that, the series of parts were made into a holistic reference registration instrument using 3D printing technology, and the patient's data for bone and surrounding tissue, along with digital 3D information of the reference registration instrument, were imported into the head‐mounted display (HMD). During the operation, the disinfected reference registration instrument was installed on the selected bony landmark, and then the automatic real‐time registration was realized by HMD through recognizing the registration landmark on the reference registration instrument, whereby the patient's virtual bone and other anatomical structures were quickly and accurately superimposed on the real body of the patient. To the best of our knowledge, this is the first report to use MR combined with 3D printing technology in total hip arthroplasty. 相似文献
8.
9.
10.
Gui-Qi Zhu Ke-Qing Shi Sha Huang Gui-Qian Huang Yi-Qian Lin Zhi-Rui Zhou Martin Braddock Yong-Ping Chen Ming-Hua Zheng 《Medicine》2015,94(11)
Major ursodeoxycholic acid (UDCA)-based therapies for primary biliary cirrhosis (PBC) include UDCA only, or combined with either methotrexate (MTX), corticosteroids (COT), colchicine (COC), or bezafibrate (BEF). As the optimum treatment regimen is unclear and warrants exploration, we aimed to compare these therapies in terms of patient mortality or liver transplantation (MOLT) and adverse events (AE).PubMed, the Cochrane Library, and Scopus were searched for randomized controlled trials up to August 31, 2014. We estimated the hazard ratios (HRs) for MOLT and odds ratios (ORs) for AE. A sensitivity analysis based on the dose of UDCA was also executed.Thirty-one eligible articles were included. Compared with COT plus UDCA, UDCA (HR 0.38, 95% confidence interval [CI] 0.09–1.39), BEF plus UDCA (HR 0.29, 95% CI 0.02–4.83), COC plus UDCA (HR 0.39, 95% CI 0.07–2.25), MTX plus UDCA (HR 0.28, 95% CI 0.05–1.63), or OBS (HR 0.49, 95% CI 0.11–2.01) all provided an increased risk of MOLT. With respect to drug AE profile, although not differing appreciably, BEF plus UDCA was associated with more AEs compared with UDCA (OR 3.16, 95% CI 0.59–20.67), COT plus UDCA (OR 2.27, 95% CI 0.15–33.36), COC plus UDCA (OR 1.00, 95% CI 0.09–12.16), MTX plus UDCA (OR 2.03, 95% CI 0.23–17.82), or OBS (OR 3.00, 95% CI 0.53–20.75). The results of sensitivity analyses were highly consistent with previous analyses.COT plus UDCA was the optimal UDCA-based regimen for both MOLT and AEs. BEF plus UDCA was most likely to cause AEs, whereas monotherapy with UDCA and coadministriation of COT plus UDCA appeared to be associated with the fewest AEs for PBC treatment. 相似文献