全文获取类型
收费全文 | 12185篇 |
免费 | 599篇 |
国内免费 | 202篇 |
专业分类
耳鼻咽喉 | 40篇 |
儿科学 | 197篇 |
妇产科学 | 63篇 |
基础医学 | 1944篇 |
口腔科学 | 889篇 |
临床医学 | 1939篇 |
内科学 | 2231篇 |
皮肤病学 | 114篇 |
神经病学 | 601篇 |
特种医学 | 245篇 |
外科学 | 1344篇 |
综合类 | 1171篇 |
预防医学 | 478篇 |
眼科学 | 84篇 |
药学 | 1106篇 |
1篇 | |
中国医学 | 449篇 |
肿瘤学 | 90篇 |
出版年
2024年 | 24篇 |
2023年 | 195篇 |
2022年 | 721篇 |
2021年 | 1174篇 |
2020年 | 448篇 |
2019年 | 391篇 |
2018年 | 422篇 |
2017年 | 356篇 |
2016年 | 379篇 |
2015年 | 390篇 |
2014年 | 721篇 |
2013年 | 890篇 |
2012年 | 636篇 |
2011年 | 699篇 |
2010年 | 495篇 |
2009年 | 543篇 |
2008年 | 506篇 |
2007年 | 474篇 |
2006年 | 447篇 |
2005年 | 397篇 |
2004年 | 332篇 |
2003年 | 285篇 |
2002年 | 196篇 |
2001年 | 188篇 |
2000年 | 140篇 |
1999年 | 151篇 |
1998年 | 122篇 |
1997年 | 110篇 |
1996年 | 129篇 |
1995年 | 102篇 |
1994年 | 92篇 |
1993年 | 68篇 |
1992年 | 80篇 |
1991年 | 50篇 |
1990年 | 72篇 |
1989年 | 64篇 |
1988年 | 54篇 |
1987年 | 44篇 |
1986年 | 42篇 |
1985年 | 56篇 |
1984年 | 44篇 |
1983年 | 38篇 |
1982年 | 55篇 |
1981年 | 27篇 |
1980年 | 30篇 |
1979年 | 18篇 |
1978年 | 24篇 |
1977年 | 15篇 |
1976年 | 19篇 |
1975年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 343 毫秒
1.
This study is focussed on micro-encapsulation of essential oils in polylactic acid (PLA) and a poly(methyl methacrylate) (PMMA) matrix as well as blends of the same. Microspheres were prepared by the solvent evaporation technique and characterised by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infra-red spectroscopy (FTIR). The encapsulation efficiencies and release profiles of the essential oils were studied by gas chromatography mass spectrometry (GC-MS) and head-space solid-phase microextraction GC-MS, respectively. Furthermore, the microspheres were tested for antibacterial activity against both Gram-negative and Gram-positive bacterial strains.
The results showed that the microspheres compositions (PLA/PMMA ratio) have significant effect on their characteristics. The process adopted for preparing the microspheres promoted formation of spherical particles at the sizes of 1.5–9.5?µm. The highest encapsulation efficiency of the prepared microspheres was observed in systems consisting of linalool (81.10?±?10.0?wt. % for PLA system and 76.0?±?3.3?wt. % for PMMA system). Confirmation was also made that the release rate of the microspheres was affected by the size of the same. 相似文献
2.
3.
4.
《Pancreatology》2022,22(5):665-670
Background and objectivesHyperlipasemia is highly prevalent among coronavirus disease 2019 (COVID-19) patients. The aim of this study was to assess the effect of lipase activity, measured at the time of admission, on the clinical course and mortality in COVID-19 patients.MethodsThe population of this study comprised 12,139 patients who were hospitalized due to COVID-19 between June 2020 and June 2021 in a pandemic hospital. Of these, 8819 patients were excluded from the study due to missing data, four patients were excluded due to a diagnosis of acute pancreatitis (according to the revised Atlanta criteria), and 72 patients were excluded due to alcohol use or having a history of chronic pancreatitis. The final study sample consisted of the remaining 3244 COVID-19 patients. Laboratory results, intensive care unit (ICU) follow-up periods, the need for mechanical ventilation, and mortality rates were compared between the normal lipase activity and high lipase activity groups.ResultsThere were 968 (29.8%) patients with high lipase activity at the time of admission. The rate of ICU admission was 36.1% vs. 9.9% (p < 0.001), mechanical ventilation requirement rates were 33.7% vs. 8.3% (p < 0.001), and mortality rates were as 24.6% vs. 6.4% (p < 0.001) in the high lipase activity group compared to the normal lipase activity group. Multivariate regression analysis revealed that high lipase activity was an independent factor in predicting mortality in hospitalized COVID-19 patients (odds ratio [OR]: 3.191, p < 0.001).ConclusionElevated lipase activity without acute pancreatitis at the time of admission in COVID-19 patients was determined as an independent predictor of poor prognosis. 相似文献
5.
急性脑梗死是威胁我国人民健康的重大疾病,其致死率及致残率均较高,造成了沉重的社会负担。及时开通导致梗死的责任血管以恢复脑灌注是治疗该病的关键。机械取栓技术的应用使得患者的血栓组织能够被获取并得到研究。本文介绍了近年来通过机械取栓术获取的血栓的相关研究发现,以纤维蛋白为主的血栓是造成取栓困难的重要组织学原因,影像学方法可以在术前评估血栓特征。这些发现提示临床工作者可以积极开发新型血栓取出装置用于处理难治性血栓,并有必要探索精确便捷的血栓特征影像学评价方法,从而提高机械取栓疗效。 相似文献
6.
《Burns : journal of the International Society for Burn Injuries》2021,47(8):1896-1907
Acute pain is prevalent following burn injury and can often transition to chronic pain. Prolonged acute pain is an important risk factor for chronic pain and there is little preclinical research to address this problem. Using a mouse model of second-degree burn, we investigated whether pre-existing stress influences pain(sensitivity) after a burn injury. We introduced a contribution of stress in two different ways: (1) the use of foot-shock as a pre-injury stressor or (2) the use of A/J mice to represent higher pre-existing stress compared to C57Bl/6 mice. C57Bl/6 and A/J mice were exposed to repeated mild foot shock to induce stress for 10 continuous days and mice underwent either burn injury or sham burn injury of the plantar surface of the right hind paw. Assessments of mechanical and thermal sensitivities of the injured and uninjured paw were conducted during the shock protocol and at intervals up to 82-day post-burn injury. In both strains of mice that underwent burn injury, thermal hypersensitivity and mechanical allodynia appeared rapidly in the ipsilateral paw. Mice that were stressed took much longer to recover their hind paw mechanical thresholds to baseline compared to non-stressed mice in both burn and non-burn groups. Analysis of the two mouse strains revealed that the recovery of mechanical thresholds in A/J mice which display higher levels of baseline anxiety was shorter than C57Bl/6 mice. No differences were observed regarding thermal sensitivities between strains. Our results support the view that stress exposure prior to burn injury affects mechanical and thermal thresholds and may be relevant to as a risk factor for the transition from acute to chronic pain. Finally, genetic differences may play a key role in modality-specific recovery following burn injury. 相似文献
7.
8.
Guowei Zhang Fenger Sun Heping Liu Xiaoyan Ren Hong Xu Mingjie Wang Yizheng Fu 《Materials》2021,14(9)
The structural properties, elastic anisotropy, electronic structures and work function of D022-type Al3TM (TM = Sc, Ti, V, Y, Zr, Nb, La, Hf, Ta) are studied using the first-principles calculations. The results indicate that the obtained formation enthalpy and cohesive energy of these compounds are in accordance with the other calculated values. It is found that the Al3Zr is the most thermodynamic stable compound. The mechanical property indexes, such as elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, and Vickers hardness are systematically explored. Moreover, the calculated universal anisotropic index, percent anisotropy and shear anisotropic factors of D022-type Al3TM are analyzed carefully. It demonstrates that the shear modulus anisotropy of Al3La is the strongest, while that of Al3Ta is the weakest. In particular, the density of states at Fermi level is not zero, suggesting that these phases have metal properties and electrical conductivity. More importantly, the mechanisms of correlation between hardness and Young’s modulus are further explained by the work function. Finally, the experimental design proves that D022-Al3Ta has an excellent strengthening effect. 相似文献
9.
目的 观察SWIM技术治疗后循环大血管闭塞所致急性缺血性卒中的有效性及安全性。
方法 回顾性分析2017年2月-2018年11月于大连市中心医院采用SWIM技术治疗的后循环大血管闭
塞所致急性缺血性卒中患者的临床资料,评价该技术的疗效和安全性,并分析影响患者预后的因素。
观察指标为术后即刻成功再通(mTICI≥2b)、90 d良好预后(mRS评分≤2分),以及术后24 h任何颅内
出血、90 d全因死亡。
结果 共纳入35例患者,平均年龄66.1±12.1岁,男性26例(74.3%),基线NIHSS评分22(15~34)分。
术后即刻成功再通率为94.3%(33/35),90 d良好预后率为45.7%(16/35),24 h颅内出血率为17.1%
(6/35),90 d全因死亡率为37.1%(13/35)。单因素分析显示,基线NIHSS评分较低(P =0.001)、基
线后循环ASPECTS评分较高(P =0.016)、发病至到院时间较短(P =0.039)、发病至再通时间较短
(P =0.047)、血管成功再通率较高(P =0.036)以及饮酒比例较低(P =0.042)与良好预后相关。
结论 使用SWIM技术治疗后循环急性缺血性卒中相对安全、有效。 相似文献
10.
目的探讨研究一次性湿热交换器在新生儿机械通气长途转运中应用的临床意义。方法 2017年1月-2017年12月,我院120转运中心长途转运接收786例机械通气新生儿,786例患儿随机分为常规气道护理(对照组)和转运途中应用一次性湿热交换器组(治疗组),对比转运过程中的吸痰次数、肉眼可见痰痂形成率、堵管发生率、脱管发生率、人机对抗发生率。结果研究数据显示治疗组吸痰次数、肉眼可见痰痂形成率、堵管发生率、脱管发生率、人机对抗发生率有显著性差异(P<0.05)明显低于对照组。结论在机械通气新生儿长途转运中,一次性湿热交换器的可减少转运患儿吸痰次数发生率、降低肉眼可见痰痂形成率、堵管发生率、脱管发生率、人机对抗发生率具有明显优越性,值得推广。 相似文献