全文获取类型
收费全文 | 1270篇 |
免费 | 51篇 |
国内免费 | 31篇 |
专业分类
耳鼻咽喉 | 8篇 |
儿科学 | 5篇 |
妇产科学 | 1篇 |
基础医学 | 81篇 |
口腔科学 | 167篇 |
临床医学 | 60篇 |
内科学 | 104篇 |
皮肤病学 | 12篇 |
神经病学 | 29篇 |
特种医学 | 71篇 |
外科学 | 209篇 |
综合类 | 137篇 |
预防医学 | 196篇 |
眼科学 | 4篇 |
药学 | 207篇 |
中国医学 | 16篇 |
肿瘤学 | 45篇 |
出版年
2024年 | 6篇 |
2023年 | 13篇 |
2022年 | 33篇 |
2021年 | 53篇 |
2020年 | 64篇 |
2019年 | 32篇 |
2018年 | 43篇 |
2017年 | 26篇 |
2016年 | 40篇 |
2015年 | 33篇 |
2014年 | 90篇 |
2013年 | 105篇 |
2012年 | 61篇 |
2011年 | 90篇 |
2010年 | 70篇 |
2009年 | 69篇 |
2008年 | 74篇 |
2007年 | 76篇 |
2006年 | 47篇 |
2005年 | 37篇 |
2004年 | 33篇 |
2003年 | 32篇 |
2002年 | 12篇 |
2001年 | 32篇 |
2000年 | 14篇 |
1999年 | 24篇 |
1998年 | 21篇 |
1997年 | 9篇 |
1996年 | 12篇 |
1995年 | 9篇 |
1994年 | 10篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1991年 | 8篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 5篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有1352条查询结果,搜索用时 46 毫秒
1.
《Zeitschrift für medizinische Physik》2022,32(4):392-402
The aim of this study is to investigate the feasibility of manufacturing thin real-time relative dosimeters for clinical radiotherapy (RT) with potential applications for transmission monitoring in vivo dosimetry and pre-treatment dose verifications. Thin (≈1 μm) layers of a high sensitivity, wide bandgap semiconductor, the inorganic perovskite CsPbCl3, have been grown for the first time by magnetron sputtering on plastic substrates equipped with electrode arrays. Prototype devices have been tested in real-time configuration to evaluate the dose delivered by a 6 MV photon beam from a linear accelerator. Linearity of the charge with the dose has been verified over three order of magnitudes, linearity of the current signal with the dose rate has been also successfully tested in the range 0.5-4.3 Gy/min. The combination of high sensitivity per unit volume and wide bandgap provides high signal-to-noise ratios, up to 70, even at moderate applied voltages. The Schottky diode configuration allows the detector to operate without bias voltage (null bias).The blocking-barrier structure allows to confine the active volume within sub-millimetric sizes, a quite attractive feature in view to increase granularity and achieve the high spatial resolutions required in modern RT techniques. All the above-mentioned features indeed pave the way to a novel generation of flexible, transmission, real time dosimeters for clinical radiotherapy. 相似文献
2.
Kara S. Tanaka MD Veronica R. Andaya BA Steven W. Thorpe MD Kenneth R. Gundle MD James B. Hayden MD Yee-Cheen Duong MD Raffi S. Avedian MD David G. Mohler MD Lee J. Morse MD Melissa N. Zimel MD Richard J. O'Donnell MD Andrew Fang MD Robert Lor Randall MD Tina H. Tran BS Christin New BA Rosanna L. Wustrack MD other members of Study Group FORCE 《Journal of surgical oncology》2023,127(1):148-158
3.
4.
Michael J. Root 《Calcified tissue international》1990,47(2):112-116
Summary The induction time for amorphous calcium phosphate (ACP) phase transformation was monitored at pH 7.4 and T=25°C with [Ca2+]0=[PO4]0=4.0×10−3 M, as a function of added crystal growth inhibitors Mg2+, Sr2+, Zn2+, pyrophosphate (PP), and tripolyphosphate (TPP). Metal ions increase the induction time for the initiation of the phase change
reaction in the order Zn2+<Sr2+<Mg2+. For polyphosphates it was observed that both PP and TPP are potent inhibitors with TPP more effective than PP as expected.
The combination of Mg2+ or Sr2+ and PP or TPP leads to a synergistic delay in the onset of the phase conversion. The greatest inhibition was observed for
Mg2+ and TPP. Reaction solutions containing 2.0×10−4 M Mg2+ and 4.0×10−5 M TPP resulted in a 90% increase in the induction time over what would be anticipated from an additive effect from these
species. 相似文献
5.
【目的】 通过对金属加工杂志社搭建的全媒体平台(以下简称“金属加工全媒体平台”)特色和建设思维的研究,为科技类期刊的全媒体平台建设提供借鉴。【方法】 采用访谈法、观察法和个案分析法等对金属加工全媒体平台的建设和运营情况进行资料收集、思考和分析。【结果】 金属加工全媒体平台的特色在于它不仅是不断延展的开放式平台,也是优质内容的一站式平台,更是用户导向的服务平台,亦是杂志社主导的共建性平台。【结论】 虽然金属加工杂志社的“大而全型”全媒体平台只是科技类期刊全媒体平台的一种类型,但其平台建设中的差异化思维、用户思维和融合思维具有普适性,可以为其他科技期刊的全媒体平台建设提供参考。 相似文献
6.
中药中金属元素的生化作用机理 总被引:3,自引:0,他引:3
机体内环境是一个多层次纵横交错的大系统 ,有一套复杂的调控体系 ,金属元素与此调控体系有密切联系。机体内所有复杂的生化反应都离不开酶 ,而金属元素有的是酶的辅助因子参与酶的组成 ,有的是酶的激活剂 ,是酶活性的主要调节者。深入研究中药中金属元素对酶活性的影响 ,将有利于提高药效。此外肾虚病人血清中金属元素与正常人相比有显著差异 ,若能比较准确地测得肾虚不同阶段的金属元素图谱 ,并结合中药中各金属元素含量的不同加以针对性地治疗 ,将对提高药物对疾病的治疗效果及延缓衰老有重要意义。 相似文献
7.
Computed tomography (CT) scans are often used for postoperative imaging in orthopedics. In the presence of metallic hardware, artifacts are generated, which can hamper visualization of the CT images, and also render the study ineffective for 3-D printing. Various solutions are available to minimize metal artifacts, and radiologists can employ these before or after processing the CT study. However, the orthopedic surgeon may be faced with situations where the metal artifacts were not addressed. To counter such problems, we present three do-it-yourself (DIY) techniques that can be used to manage metal artifacts. 相似文献
8.
根据超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性结构相似原理,作者首次提出金属卟啉化合物可作为SOD和CAT双功能模拟酶,并对合成的4 种金属卟啉[四-(对磺酸基苯基)卟啉铁、四-(对磺酸基苯基)卟啉铜、四-(对磺酸基苯基)卟啉锰、四-(对磺酸基苯基)卟啉钴]进行了仿SOD和CAT的部分生物学功能检测 .结果显示:核黄素-蛋氨酸光明法证实它们在10-5~10-6mol/L浓度范围内有清除O(*2)-的作用;分光光度法证实它们能催化H2O2 的分解,且分解率随浓度增大而增大;用小鼠肝匀浆法测定4种金属卟啉、SOD和CAT,均表明有良好抗脂质过氧化作用;大鼠心脏缺血再灌注实验表明四-(对-磺酸基苯基)卟啉锰能降低活性氧对心肌的损伤程度, 对再灌注损伤心肌有保护作用. 相似文献
9.
Lander F Kristiansen J Lauritsen JM 《International archives of occupational and environmental health》1999,72(8):546-550
Objectives: Cast iron products are alloyed with small quantities of manganese, and foundry furnacemen are potentially exposed to manganese
during tapping and handling of smelts. Manganese is a neurotoxic substance that accumulates in the central nervous system,
where it may cause a neurological disorder that bears many similarities to Parkinson's disease. The aim of the study was to
investigate the sources and levels of manganese exposure in foundry furnacemen by a combined measuring of blood-manganese
(B-Mn) and manganese in ambient air (air-Mn). Methods: During a period of 16 months, Air-Mn and B-Mn (denoted `exposure values') were measured involving 24 furnacemen employed
in three small size foundries and 21 scrap recycling workers from one plant. In the study period, 18 furnacemen had B-Mn measured
3–4 weeks after decreasing or stopping exposure (denoted `post-exposure values'). The reference group for the B-Mn measurements
consisted of 90 Danish male subjects. Results: Furnacemen who work in insufficiently ventilated smelting departments inhale, absorb, and retain significant amounts of manganese
in their blood (approx. 2.5–5 μg/l above reference values) despite a generally low measured airborne level of manganese fumes
(0.002–0.064 mg/m3). The `exposure values' compared with `post-exposure values' revealed a significant decrease in the B-Mn (on average 3.7 μg/l)
level of the most exposed furnacemen. Two persons in our study were suspected of suffering clinically subacute manganese intoxication
as both had B-Mn levels beyond the normal limit (25 and 29 μg/l, respectively). The potential problem disappeared completely
after cessation of exposure, and the B-Mn levels decreased to 9.4 and 14.1 μg/l, respectively. Conclusions: Risk assessment based on combined measurements of B-Mn and air-Mn seems to be valid in the interpretation of workers' hazard.
Our study indicates that B-Mn may be a valuable parameter for estimating recent exposure (within 1–2 weeks). However, more
knowledge is needed about the B-Mn level and its relation to neurological symptoms.
Received: 20 January 1999 / Accepted: 14 June 1999 相似文献
10.
Michael WJ Hii Robert N Gibson Anthony G Speer Neil A Collier Noel Sherson Cate Jardine 《Journal of Medical Imaging and Radiation Oncology》2003,47(4):393-403
We reviewed the results of percutaneous intervention of hilar biliary malignancy over a 10‐year period at a single institution: the Royal Melbourne Hospital. Ninety‐nine patients (100 treated in total) were included. Information was retrieved by retrospective examination of patient notes and radiology, combined with interviews with family and relevant physicians. Sixty‐nine patients were treated with insertion of semipermanent stents, 19 had external drain tubes, and 25 received percutaneous access for Iridium brachytherapy. Adequate drainage was achieved in 87% of the patients stented, and percutaneous access was successful in 96% of patients planned for brachytherapy. Of those patients undergoing endoprosthesis insertion, early complications occurred in 39% and late complications in 23%. Average survival for the entire patient population was 227.3 days, with a median of 167 days. Longer survival times (213 vs 142 days) and lower complication rates (44 vs 64%) are observed with metal stents in comparison with plastic stents. Percutaneous intervention is an important treatment option in hilar biliary malignancy, particularly in patients unfit for surgery. Reasonable survival with good palliation is the most common outcome, and most patients do not require further intervention. 相似文献