全文获取类型
收费全文 | 1445674篇 |
免费 | 124957篇 |
国内免费 | 14115篇 |
专业分类
耳鼻咽喉 | 17665篇 |
儿科学 | 44380篇 |
妇产科学 | 38742篇 |
基础医学 | 196079篇 |
口腔科学 | 38215篇 |
临床医学 | 135196篇 |
内科学 | 294290篇 |
皮肤病学 | 33182篇 |
神经病学 | 116047篇 |
特种医学 | 59572篇 |
外国民族医学 | 344篇 |
外科学 | 221862篇 |
综合类 | 49993篇 |
现状与发展 | 26篇 |
一般理论 | 417篇 |
预防医学 | 113087篇 |
眼科学 | 31451篇 |
药学 | 105545篇 |
116篇 | |
中国医学 | 8134篇 |
肿瘤学 | 80403篇 |
出版年
2021年 | 12819篇 |
2019年 | 12996篇 |
2018年 | 17383篇 |
2017年 | 14195篇 |
2016年 | 16129篇 |
2015年 | 19344篇 |
2014年 | 26272篇 |
2013年 | 35574篇 |
2012年 | 44813篇 |
2011年 | 48307篇 |
2010年 | 30159篇 |
2009年 | 28461篇 |
2008年 | 42598篇 |
2007年 | 45021篇 |
2006年 | 46173篇 |
2005年 | 44760篇 |
2004年 | 40980篇 |
2003年 | 39816篇 |
2002年 | 37161篇 |
2001年 | 68729篇 |
2000年 | 70615篇 |
1999年 | 59365篇 |
1998年 | 18046篇 |
1997年 | 16241篇 |
1996年 | 16705篇 |
1995年 | 17560篇 |
1994年 | 16253篇 |
1993年 | 14861篇 |
1992年 | 48112篇 |
1991年 | 46658篇 |
1990年 | 44736篇 |
1989年 | 42487篇 |
1988年 | 39331篇 |
1987年 | 38603篇 |
1986年 | 36243篇 |
1985年 | 34989篇 |
1984年 | 26532篇 |
1983年 | 22212篇 |
1982年 | 13910篇 |
1981年 | 12506篇 |
1979年 | 23601篇 |
1978年 | 17069篇 |
1977年 | 14369篇 |
1976年 | 13177篇 |
1975年 | 13735篇 |
1974年 | 16118篇 |
1973年 | 15409篇 |
1972年 | 14186篇 |
1971年 | 13042篇 |
1970年 | 11874篇 |
排序方式: 共有10000条查询结果,搜索用时 17 毫秒
21.
22.
23.
24.
25.
Paul G. Richardson Fredrik Schjesvold Katja Weisel Philippe Moreau Larry D. Anderson Darrell White Paula Rodriguez-Otero Pieter Sonneveld Monika Engelhardt Matthew Jenner Alessandro Corso Jan Dürig Michel Pavic Morten Salomo Meral Beksac Albert Oriol Jindriska Lindsay Anna Marina Liberati Monica Galli Pawel Robak Alessandra Larocca Munci Yagci Filiz Vural Abraham S. Kanate Ruiyun Jiang Lara Grote Teresa Peluso Meletios Dimopoulos 《European journal of haematology》2022,108(1):73-83
26.
27.
目的 评价美国国家电器制造协会(National Electrical Manufactures Association, NEMA)最新标准(NU 2-2018)在正电子发射型计算机断层显像/电子计算机断层显像(positron emission tomography/computed tomography, PET/CT)设备性能检测中的作用。 方法 依据最新的NEMA NU 2-2018标准,检测西门子Biograph Vision PET/CT的空间分辨率、灵敏度、散射分数、计数丢失、随机符合、飞行时间分辨率、计数丢失率和随机符合校正精度、图像质量、衰减和散射校正精度及PET与CT配准精度指标。 结果 距视野中心1 cm处横向和轴向空间分辨率分别为3.75 mm和3.76 mm;在视野中心和轴向10 cm处的灵敏度分别为16.83 kcps/MBq和16.67 kcps/MBq;放射性浓度为27.37 kBq/mL时,最大等效噪声计数率为258.26 kcps,散射分数为38.58%;系统时间分辨率为209.82 ps;图像质量模型的对比度恢复系数范围为88.9%~96.2%,背景变异系数范围为2.05%~6.80%,平均肺插件残余误差为2.43%;计数丢失和随机符合校正最大误差为3.9%;距离床板末端 5 cm 和 100 cm处,在距视野中心Y轴1 cm处,PET和CT的配准精度分别为0.46 mm和1.07 mm,在距视野中心X轴20 cm处,PET和CT的配准精度分别为1.06 mm和1.45 mm,在距视野中心Y轴20 cm处PET和CT的配准精度分别为0.85 mm和1.15 mm。 结论 NEMA NU 2-2018标准检测条件更加接近临床,能更好地反映PET/CT设备的系统性能。 相似文献
28.
A Coupled FEM-BEM Approach for the Solution of the Free-Boundary Axi-Symmetric Plasma Equilibrium Problem 下载免费PDF全文
M. Bonotto D. Abate P. Bettini & F. Villone 《Communications In Computational Physics》2022,31(1):27-59
In this paper we present a coupled Finite Element Method – Boundary Element Method (FEM-BEM) approach for the solution of the free-boundary axi-symmetric
plasma equilibrium problem. The proposed method, obtained from an improvement
of the Hagenow-Lackner coupling method, allows to efficiently model the equilibrium
problem in unbounded domains by discretizing only the plasma region; the external
conductors can be modelled either as 2D or 3D models, according to the problem of interest. The paper explores different iterative methods for the solution of the nonlinear
Grad-Shafranov equation, such as Picard, Newton-Raphson and Newton-Krylov, in order to provide a robust and reliable tool, able to handle large-scale problems (e.g. high
resolution equilibria). This method has been implemented in the FRIDA code (FRee-boundary Integro-Differential Axisimmetric – https://github.
om/matteobonotto/
FRIDA), together with a suitable Adaptive Integration Technique (AIT) for the computation of the source term. FRIDA has been successfully tested and validated against
experimental data from RFX-mod device, and numerical equilibria of an ITER-like device. 相似文献
29.
30.
Wuteng Cao Huabin Hu Jiao Li Qianyu Wu Lishuo Shi Biao Li Jie Zhou Xinhua Wang Junhong Chen Chao Wang Huaiming Wang Weihao Deng Yan Huang Yanhong Deng 《International journal of cancer. Journal international du cancer》2023,153(11):1894-1903
Neoadjuvant programmed cell death protein 1 (PD-1) blockade exhibits promising efficacy in patients with mismatch repair deficient (dMMR) colorectal cancer (CRC). However, discrepancies between radiological and histological findings have been reported in the PICC phase II trial (NCT 03926338). Therefore, we strived to discern radiological features associated with pathological complete response (pCR) based on computed tomography (CT) images. Data were obtained from the PICC trial that included 36 tumors from 34 locally advanced dMMR CRC patients, who received neoadjuvant PD-1 blockade for 3 months. Among the 36 tumors, 28 (77.8%) tumors achieved pCR. There were no statistically significant differences in tumor longitudinal diameter, the percentage change in tumor longitudinal diameter from baseline, primary tumor sidedness, clinical stage, extramural venous invasion status, intratumoral calcification, peritumoral fat infiltration, intestinal fistula and tumor necrosis between the pCR and non-pCR tumors. Otherwise, tumors with pCR had smaller posttreatment tumor maximum thickness (median: 10 mm vs 13 mm, P = .004) and higher percentage decrease in tumor maximum thickness from baseline (52.9% vs 21.6%, P = .005) compared to non-pCR tumors. Additionally, a higher proportion of the absence of vascular sign (P = .003, odds ratio [OR] = 25.870 [95% CI, 1.357-493.110]), nodular sign (P < .001, OR = 189.000 [95% CI, 10.464-3413.803]) and extramural enhancement sign (P = .003, OR = 21.667 [2.848-164.830]) was observed in tumors with pCR. In conclusion, these CT-defined radiological features may have the potential to serve as valuable tools for clinicians in identifying patients who have achieved pCR after neoadjuvant PD-1 blockade, particularly in individuals who are willing to adopt a watch-and-wait strategy. 相似文献