全文获取类型
收费全文 | 2865篇 |
免费 | 452篇 |
国内免费 | 85篇 |
专业分类
3402篇 |
出版年
2024年 | 21篇 |
2023年 | 55篇 |
2022年 | 74篇 |
2021年 | 111篇 |
2020年 | 108篇 |
2019年 | 142篇 |
2018年 | 122篇 |
2017年 | 121篇 |
2016年 | 128篇 |
2015年 | 114篇 |
2014年 | 215篇 |
2013年 | 198篇 |
2012年 | 133篇 |
2011年 | 155篇 |
2010年 | 131篇 |
2009年 | 140篇 |
2008年 | 157篇 |
2007年 | 173篇 |
2006年 | 175篇 |
2005年 | 157篇 |
2004年 | 106篇 |
2003年 | 106篇 |
2002年 | 102篇 |
2001年 | 50篇 |
2000年 | 60篇 |
1999年 | 46篇 |
1998年 | 54篇 |
1997年 | 33篇 |
1996年 | 40篇 |
1995年 | 24篇 |
1994年 | 27篇 |
1993年 | 23篇 |
1992年 | 41篇 |
1991年 | 9篇 |
1990年 | 5篇 |
1989年 | 7篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 5篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 7篇 |
1977年 | 3篇 |
1974年 | 1篇 |
排序方式: 共有3402条查询结果,搜索用时 0 毫秒
41.
Etienne X. Keller Vincent de Coninck Marie Audouin Steeve Doizi Dominique Bazin Michel Daudon Olivier Traxer 《Journal of biophotonics》2019,12(4)
Urinary stones can be readily disintegrated by Holmium:YAG laser (Holmium laser lithotripsy), resulting in a mixture of small stone dust particles, which will spontaneously evacuate with urine and larger residual fragments (RF) requiring mechanical retrieval. Differences between fragments and dust have not been well characterized. Also, it remains unknown how the recently introduced “Moses technology” may alter stone disintegration products. Three complementary analytical techniques have been used in this study to offer an in‐depth characterization of disintegration products after in vitro Holmium laser lithotripsy: stereoscopic microscopy, scanning electron microscopy and Fourier‐transform infrared spectroscopy. Dust was separated from fragments based on its floating ability in saline irrigation. Depending on initial crystalline constituents, stone dust either conserved attributes found in larger RFs or showed changes in crystalline organization. These included conversion of calcium oxalate dihydrate towards calcium oxalate monohydrate, changes in carbapatite spectra towards an amorphous phase, changes of magnesium ammonium phosphate towards a differing amorphous and crystalline phase and the appearance of hydroxyapatite on brushite fragments. Comparatively, “Moses technology” produced more pronounced changes. These findings provide new insights suggesting a photothermal effect occurring in Holmium laser lithotripsy. Figure: Appearance of hydroxyapatite hexagons on stone dust collected after Holmium laser lithotripsy of a brushite stone using “Moses technology.” 相似文献
42.
目的:探讨肺叶手术中超前应用氟比洛芬酯对减轻全身麻醉苏醒期躁动发生率的影响。方法:60例肺叶切除术患者随机分为A组和B组,每组30例,两组均常规诱导全麻气管插管,术中瑞芬、丙泊酚、维库溴铵泵住维持麻醉,A组于术前给予氟比洛芬酯1 MG/KG。比较两组躁动得分、苏醒后(10 min、30 min、1 h、2 h、4 h、24 h)六个时间点疼痛评分及不良反应发生率。结果:两组出血时间、拔管时间、麻醉时间差异均无统计学意义(均P0.05);A组患者的躁动得分显著低于B组,差异有统计学意义(P0.05);两组的VAS评分差异有统计学意义(P0.05),不同时间点的VAS评分差异有统计学意义(P0.05),分组与时间之间存在交互作用(P0.05);A组患者的不良反应发生率低于B组,差异有统计学意义(P0.05)。结论:肺叶手术中超前应用氟比洛芬酯具有良好的镇痛效果,可以降低全身麻醉苏醒期躁动的发生率。 相似文献
43.
Controlling the near‐infrared transparency of costal cartilage by impregnation with clearing agents and magnetite nanoparticles 下载免费PDF全文
Yulia Alexandrovskaya Kirill Sadovnikov Andrey Sharov Anna Sherstneva Evgeniy Evtushenko Alexander Omelchenko Mariya Obrezkova Valery Tuchin Valery Lunin Emil Sobol 《Journal of biophotonics》2018,11(2)
Penetration depth of near‐infrared laser radiation to costal cartilage is controlled by the tissue absorption and scattering, and it is the critical parameter to provide the relaxation of mechanical stress throughout the whole thickness of cartilage implant. To enhance the penetration for the laser radiation on 1.56 μm, the optical clearing solutions of glycerol and fructose of various concentrations are tested. The effective and reversible tissue clearance was achieved. However, the increasing absorption of radiation should be concerned: 5°C‐8°C increase of tissue temperature was detected. Laser parameters used for stress relaxation in cartilage should be optimized when applying optical clearing agents. To concentrate the absorption in the superficial tissue layers, magnetite nanoparticle (NP) dispersions with the mean size 95 ± 5 nm and concentration 3.9 ± 1.1 × 1011 particles/mL are applied. The significant increase in the tissue heating rate was observed along with the decrease in its transparency. Using NPs the respective laser power can be decreased, allowing us to obtain the working temperature locally with reduced thermal effect on the surrounding tissue. 相似文献
44.
45.
Eggers C Obliers R Koerfer A Thomas W Koehle K Hoelscher AH Bollschweiler E 《Obesity (Silver Spring, Md.)》2007,15(11):2866-2873
Objective: Severe obesity is a clear indication for appropriate, effective weight loss therapy. One option is operative intervention, e.g., gastric banding. Risks of the operation and therapeutic alternatives need to be comprehensibly presented to the patient. The literature has shown that better informed consent is obtained using information presented in a multimedia/video‐based format. The current study developed and evaluated a multimedia program aimed at obtaining informed consent from obese patients before gastric banding. Research Methods and Procedure: An interactive multimedia program was developed with information about preoperative examinations, the operation itself, hospital stay, operative risks, alternative therapies, and the pathophysiology and health risks of obesity. Two groups (Group 1, n = 20, mean age 38 years, informed consent attained with conventional document information; Group 2, n = 20, mean age 37 years, informed consent attained with additional multimedia information) were interviewed regarding comprehensibility of the information presented, personal satisfaction, and anxiety levels during the informed consent process. Results: Group 2 showed significantly better (p < 0.05) understanding of the presented information and higher levels of satisfaction with the informed consent process. Anxiety levels did not significantly differ between the two groups. Discussion: Because patient satisfaction with the informed consent process and understanding of the presented information significantly improved, the multimedia program clearly benefits both surgeons and patients. Personal contact from the surgeon remains essential. High volumes of information presented in multimedia format do not alleviate patient anxiety, and personal contact may be beneficial. 相似文献
46.
Amino groups of human serum albumin (HSA) can react non-enzymatically with carbonyl groups of reducing sugars to form advanced glycation end products (AGEs). These AGEs contribute to many of the chronic complications of diabetes including atherosclerosis, cataract formation and renal failure. The current study focused on in vitro non-enzymatic reactivity of glyceraldehyde (GA) and methylglyoxal (MG) with HSA and evaluated the rate and extent of AGE formation in the presence of varied concentrations of Zn(II). At normal physiological conditions, GA and MG readily react with HSA. The presence of Zn(II) in HSA-GA or HSA-MG incubation mixtures reduced AGE formation. This finding was confirmed by UV and fluorescence spectrometry, HPLC techniques, and matrix assisted laser desorption ionization mass spectrometry (MALDI-TOF). HPLC studies revealed decreased adduct formation of the glycated protein in the presence of Zn(II). The inhibition of AGE formation was intense at elevated Zn(II) concentrations. The results of this study suggest that Zn(II) may prove to be a potent agent in reducing AGE formation. 相似文献
47.
The combination of a hydrophilic embedding resin, Nanoplast, with fluorescent probes, and subsequent imaging using two-photon
and confocal laser scanning microscopy (2P-LSM and CLSM) has allowed in imaging of the in situ microspatial arrangements of
microbial cells and their extracellular polymeric secretion (EPS) within marine stromatolites. Optical sectioning by 2P-LSM
and CLSM allowed imaging of endolithic cyanobacteria cells, Solentia sp., seen within carbonate sand grains. 2P-LSM allowed very clear imaging with a high resolution of bacteria using DAPI,
which normally require UV excitation and reduced photo-bleaching of fluorescent probes. 相似文献
48.
目的:总结改良Nikaidoh手术治疗右心室双出口(DORV)患者的临床经验,以提高手术疗效。方法:2例先天性心脏病右心室双出口伴肺动脉瓣狭窄行改良Nikaidoh手术,游离主动脉根部及冠状动脉,重建左心室流出道,以带单瓣牛心包片补片重建肺动脉及右心室流出道。结果:术后患者紫绀消失,复查心脏彩超仅有轻度肺动脉瓣关闭不全,未发现左、右心室流出道梗阻,康复出院。结论:采用改良Nikaidoh手术治疗伴肺动脉瓣狭窄的右室双出口,术后可获得良好的血流动力学效果,早期临床结果满意。 相似文献
49.
Molecular basis of guanine nucleotide dissociation inhibitor activity of human neuroglobin by chemical cross-linking and mass spectrometry 总被引:1,自引:0,他引:1
Kitatsuji C Kurogochi M Nishimura S Ishimori K Wakasugi K 《Journal of molecular biology》2007,368(1):150-160
Oxidized human neuroglobin (Ngb), a heme protein expressed in the brain, has been proposed to act as a guanine nucleotide dissociation inhibitor (GDI) for the GDP-bound form of the heterotrimeric G protein alpha-subunit (Galpha(i)). Here, to elucidate the molecular mechanism underlying the GDI activity of Ngb, we used an glutathione-S-transferase pull-down assay to confirm that Ngb competes with G-protein betagamma-subunits (Gbetagamma) for binding to Galpha(i), and identified the Galpha(i)-binding site in Ngb by chemical cross-linking with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and sulfo-N-hydroxysuccinimide, coupled with mass spectrometry (MS). Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS analysis for tryptic peptides derived from the cross-linked Ngb-Galpha(i) complex revealed several binding regions in Ngb. Furthermore, MALDI-TOF/TOF MS analysis of the cross-linked Ngb and Galpha(i) peptides, together with the MS/MS scoring method, predicted cross-linking between Glu60 (Ngb) and Ser206 (Galpha(i)), and between Glu53 (Ngb) and Ser44 (Galpha(i)). Because Ser206 of Galpha(i) is located in the region that contacts Gbetagamma, binding of Ngb could facilitate the release of Gbetagamma from Galpha(i). Binding of Ngb to Galpha(i) would also inhibit the exchange of GDP for GTP, because Ser44 (Galpha(i)) is adjacent to the GDP-binding site and Glu53 (Ngb), which is cross-linked to Ser44 (Galpha(i)), could be located close to GDP. Thus, we have identified, for the first time, the sites of interaction between Ngb and Galpha(i), enabling us to discuss the functional significance of this binding on the GDI activity of Ngb. 相似文献
50.