全文获取类型
收费全文 | 15154篇 |
免费 | 1219篇 |
国内免费 | 265篇 |
专业分类
耳鼻咽喉 | 125篇 |
儿科学 | 405篇 |
妇产科学 | 276篇 |
基础医学 | 1535篇 |
口腔科学 | 265篇 |
临床医学 | 2221篇 |
内科学 | 2735篇 |
皮肤病学 | 82篇 |
神经病学 | 1055篇 |
特种医学 | 1274篇 |
外国民族医学 | 1篇 |
外科学 | 2096篇 |
综合类 | 1494篇 |
预防医学 | 601篇 |
眼科学 | 149篇 |
药学 | 1089篇 |
11篇 | |
中国医学 | 228篇 |
肿瘤学 | 996篇 |
出版年
2024年 | 44篇 |
2023年 | 293篇 |
2022年 | 506篇 |
2021年 | 758篇 |
2020年 | 751篇 |
2019年 | 659篇 |
2018年 | 682篇 |
2017年 | 556篇 |
2016年 | 510篇 |
2015年 | 522篇 |
2014年 | 978篇 |
2013年 | 1020篇 |
2012年 | 726篇 |
2011年 | 873篇 |
2010年 | 637篇 |
2009年 | 694篇 |
2008年 | 636篇 |
2007年 | 671篇 |
2006年 | 561篇 |
2005年 | 467篇 |
2004年 | 387篇 |
2003年 | 323篇 |
2002年 | 253篇 |
2001年 | 229篇 |
2000年 | 196篇 |
1999年 | 188篇 |
1998年 | 193篇 |
1997年 | 190篇 |
1996年 | 161篇 |
1995年 | 153篇 |
1994年 | 152篇 |
1993年 | 151篇 |
1992年 | 138篇 |
1991年 | 106篇 |
1990年 | 126篇 |
1989年 | 116篇 |
1988年 | 116篇 |
1987年 | 72篇 |
1986年 | 89篇 |
1985年 | 96篇 |
1984年 | 100篇 |
1983年 | 81篇 |
1982年 | 100篇 |
1981年 | 64篇 |
1980年 | 42篇 |
1979年 | 45篇 |
1978年 | 49篇 |
1977年 | 41篇 |
1976年 | 39篇 |
1975年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
971.
ObjectivesTo investigate the correlation between the imaging features obtained by an automated breast volume scanner (ABVS) and molecular subtypes of breast cancer.MethodsWe examined 303 malignant breast tumours by ABVS for specific imaging features and by immunohistochemical analysis to determine the molecular subtype. ABVS imaging features, including retraction phenomenon, shape, margins, echogenicity, post-acoustic features, echogenic halo, and calcifications were analysed by univariate and multivariate logistic regression analyses to determine the significant predictive factors of the molecular subtypes.ResultsBy univariate logistic regression analysis, the predictive factors of the Luminal-A subtype (n = 128) were retraction phenomenon (odds ratio [OR] = 10.188), post-acoustic shadowing (OR = 5.112), and echogenic halo (OR = 3.263, P < 0.001). The predictive factors of the Human-epidermal-growth-factor-receptor-2-amplified subtype (n = 39) were calcifications (OR = 6.210), absence of retraction phenomenon (OR = 4.375), non-mass lesions (OR = 4.286, P < 0.001), absence of echogenic halo (OR = 3.851, P = 0.035), and post-acoustic enhancement (OR = 3.641, P = 0.008). The predictors for the Triple-Negative subtype (n = 47) were absence of retraction phenomenon (OR = 5.884), post-acoustic enhancement (OR = 5.255, P < 0.001), absence of echogenic halo (OR = 4.138, P = 0.002), and absence of calcifications (OR = 3.363, P = 0.001). Predictors for the Luminal-B subtype (n = 89) had a relatively lower association (OR ≤ 2.328). By multivariate logistic regression analysis, retraction phenomenon was the strongest independent predictor for the Luminal-A subtype (OR = 9.063, P<0.001) when present and for the Triple-Negative subtype (OR = 4.875, P<0.001) when absent.ConclusionsABVS imaging features, especially retraction phenomenon, have a strong correlation with the molecular subtypes, expanding the scope of ultrasound in identifying breast cancer subtypes with confidence. 相似文献
972.
Andreas Eich Veronika Urban Marek Jutel Jiri Vlcek Jae Jeong Shim Vasiliy I. Trofimov 《COPD》2017,14(5):476-483
Interleukin (IL)-17A may be an underlying factor in the pathophysiology of chronic obstructive pulmonary disease (COPD). Anti-IL-17 monoclonal antibodies have been used successfully in treating several immune-mediated inflammatory diseases. This phase 2, randomized, placebo-controlled, double-blind, parallel-group, proof-of-concept study is the first clinical study evaluating the efficacy and safety of the anti-IL-17A monoclonal antibody CNTO 6785 in patients with symptomatic moderate-to-severe COPD. Patients were treated with CNTO 6785 (n = 93) or placebo (n = 94) intravenously at Weeks 0, 2, and 4 (induction), then Weeks 8 and 12, and followed till Week 24. The primary efficacy endpoint was the change from baseline in pre-bronchodilator percent-predicted forced expiratory volume in 1 second at Week 16. Samples were collected at all visits for pharmacokinetic (PK) evaluation, and standard safety assessments were performed. The mean difference in the primary efficacy endpoint between CNTO 6785 and placebo was not statistically significant (?0.49%; p = 0.599). No other efficacy endpoints demonstrated clinically or statistically significant differences with CNTO 6785 compared with placebo. CNTO 6785 was generally well tolerated; no major safety signals were detected. The most frequently reported treatment-emergent adverse events were infections and infestations; however, no notable differences were observed between CNTO 6785 and placebo in terms of rates of infections. PK results suggested that the steady state of serum CNTO 6785 concentration was reached within 16 weeks. These results suggest that IL-17A is unlikely to be a dominant driver in the pathology of, or a viable therapeutic target for, COPD. ClinicalTrials.gov Identifier: NCT01966549; EudraCT Identifier: 2012-003607-36. 相似文献
973.
Shing-Moo Huang Chung-Chin Yao Huichin Pan Kuang-Ming Hsiao Ji-Kuen Yu Te-Jen Lai Shueh-Ding Huang 《World journal of gastroenterology : WJG》2010,16(34):4341-4347
AIM: To study the pathophysiological significance of gallbladder volume (GBV) and ejection fraction changes in gallstone patients.METHODS: The fasting GBV of gallstone patients with acute cholecystitis (n = 99), chronic cholecystitis (n = 85) and non-gallstone disease (n = 240) were measured by preoperative computed tomography. Direct saline injection measurements of GBV after cholecystectomy were also performed. The fasting and postprandial GBV of 65 patients with gallstones and chronic cholecystitis and 5... 相似文献
974.
Yorck Olaf Schumacher Sebastian Ruthardt Michael Schmidt Christoph Ahlgrim Kai Roecker Torben Pottgiesser 《European journal of applied physiology》2009,105(5):779-785
The oxygen transport system is an important component in the limitation of endurance performance in able-bodied and paraplegic
athletes. The aim of the present study was to investigate the total haemoglobin mass (tHb, carbon monoxide rebreathing method)
and cardiac volume (HV, echocardiography) in 25 highly endurance trained male spinal cord injured (mainly paraplegic) athletes
(SCI-TRAINED) and to compare the results with those of 10 untrained spinal cord injured controls (SCI-UNTRAINED) and in 25
able-bodied elite endurance athletes (TRAINED). tHb and tHb/kg were higher in SCI-TRAINED than in SCI-UNTRAINED (748 ± 110
vs. 629 ± 209 g (464 ± 68 vs. 390 ± 130 mmol) (mean ± SD), P = 0.02 and 10.3 ± 1.3 vs. 7.9 ± 2.0 g/kg (6.4 ± 0.8 vs. 4.9 ± 1.2 mmol/kg), P < 0.0001), while HV and HV/kg showed no significant differences between the two groups (765 ± 93 vs. 793 ± 164 ml and 10.6 ± 1.4
vs. 10.3 ± 2.5 ml/kg). No difference between SCI-TRAINED and TRAINED was found for septal diameter (9.5 ± 1.0 mm vs. 9.7 ± 0.7 mm).
However, tHb and tHb/kg in SCI-TRAINED was lower than in TRAINED [896 ± 123 g (556 ± 76 mmol), P = 0.0003 and 12.6 ± 1.3 g/kg (7.8 ± 0.8 mmol), P < 0.0001]. In spinal cord injured athletes, tHb but not HV adapts moderately to chronic endurance exercise, although tHb
in spinal cord injured athletes does not reach the level of able-bodied-trained persons. 相似文献
975.
976.
977.
978.
M. Haranczyk J. A. Sethian 《Proceedings of the National Academy of Sciences of the United States of America》2009,106(51):21472-21477
Predicting whether a molecule can traverse chemical labyrinths of channels, tunnels, and buried cavities usually requires performing computationally intensive molecular dynamics simulations. Often one wants to screen molecules to identify ones that can pass through a given chemical labyrinth or screen chemical labyrinths to identify those that allow a given molecule to pass. Because it is impractical to test each molecule/labyrinth pair using computationally expensive methods, faster, approximate methods are used to prune possibilities, “triaging” the ability of a proposed molecule to pass through the given chemical labyrinth. Most pruning methods estimate chemical accessibility solely on geometry, treating atoms or groups of atoms as hard spheres with appropriate radii. Here, we explore geometric configurations for a moving “molecular worm,” which replaces spherical probes and is assembled from solid blocks connected by flexible links. The key is to extend the fast marching method, which is an ordered upwind one-pass Dijkstra-like method to compute optimal paths by efficiently solving an associated Eikonal equation for the cost function. First, we build a suitable cost function associated with each possible configuration, and second, we construct an algorithm that works in ensuing high-dimensional configuration space: at least seven dimensions are required to account for translational, rotational, and internal degrees of freedom. We demonstrate the algorithm to study shortest paths, compute accessible volume, and derive information on topology of the accessible part of a chemical labyrinth. As a model example, we consider an alkane molecule in a porous material, which is relevant to designing catalysts for oil processing. 相似文献
979.
《Platelets》2013,24(4):263-266
Aspirin is one of the preferred therapies in the primary prevention of ischemic stroke in paroxysmal atrial fibrillation (PAF). Mean platelet volume (MPV) is a marker of platelet size and activation. Increased MPV reflects active and large platelets. The present observational study was designed to investigate whether aspirin treatment does affect MPV levels in patients with PAF. The study included 101 patients who were detected to have PAF by 24-hour Holter monitoring and divided into two groups based on aspirin treatment [ASA (+) and ASA (?)]. MPV was measured. Patients with aortic and mitral stenosis, hyperthyroidism, hypothyroidism, malignancy, infection, and pregnancy were excluded from the study. Of the 101 patients, 50 had no antiplatelet therapy and 51 had daily aspirin (100?mg) intake. Mean age of the patients was 66?±?10 years and 35 (68%) were male in ASA (+) group. There was no difference in median levels of MPV (9.9 vs. 10.2?fl, respectively; p?=?0.9) between groups. Both uni- and multivariate logistic regression analyses did not show an association between MPV and ASA use. Our results indicate that MPV as a predictive marker of platelet size and activity is not affected by aspirin use in patients with PAF. 相似文献
980.
目前,心输出量(CO)监测最常使用的金标准是热稀释法的肺动脉导管技术.现在一些创伤性小,可以避免肺动脉导管操作风险的技术也开始用于监测心输出量[1].其通过分析动脉波形估算心输出量和其他血流动力学指标,可连续监测[2].对剖宫产患者施行腰麻可能造成母体严重低血压,心输出量下降,胎盘血供减少[3].预防和纠正腰麻下剖宫产术中的血流动力学不稳定曾是研究焦点,但大多数研究均使用无创监测设备评价术中血流动力学的变化[4].本研究旨在使用Flotrac/VigileoTM系统监测腰麻下行择期剖宫产的健康孕妇的血流动力学变化. 相似文献