全文获取类型
收费全文 | 4186篇 |
免费 | 349篇 |
国内免费 | 147篇 |
专业分类
耳鼻咽喉 | 18篇 |
儿科学 | 7篇 |
妇产科学 | 8篇 |
基础医学 | 259篇 |
口腔科学 | 1387篇 |
临床医学 | 165篇 |
内科学 | 801篇 |
皮肤病学 | 21篇 |
神经病学 | 69篇 |
特种医学 | 55篇 |
外国民族医学 | 1篇 |
外科学 | 424篇 |
综合类 | 499篇 |
预防医学 | 154篇 |
眼科学 | 10篇 |
药学 | 411篇 |
1篇 | |
中国医学 | 353篇 |
肿瘤学 | 39篇 |
出版年
2024年 | 15篇 |
2023年 | 95篇 |
2022年 | 342篇 |
2021年 | 489篇 |
2020年 | 167篇 |
2019年 | 146篇 |
2018年 | 143篇 |
2017年 | 151篇 |
2016年 | 138篇 |
2015年 | 141篇 |
2014年 | 270篇 |
2013年 | 334篇 |
2012年 | 232篇 |
2011年 | 243篇 |
2010年 | 158篇 |
2009年 | 175篇 |
2008年 | 156篇 |
2007年 | 136篇 |
2006年 | 130篇 |
2005年 | 133篇 |
2004年 | 111篇 |
2003年 | 101篇 |
2002年 | 101篇 |
2001年 | 74篇 |
2000年 | 49篇 |
1999年 | 59篇 |
1998年 | 51篇 |
1997年 | 29篇 |
1996年 | 30篇 |
1995年 | 33篇 |
1994年 | 34篇 |
1993年 | 23篇 |
1992年 | 39篇 |
1991年 | 27篇 |
1990年 | 16篇 |
1989年 | 18篇 |
1988年 | 18篇 |
1987年 | 14篇 |
1986年 | 15篇 |
1985年 | 23篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1976年 | 3篇 |
排序方式: 共有4682条查询结果,搜索用时 46 毫秒
141.
Lizhen Cheng Ting Li Ling Dong Xiaoyu Wang Qiye Huo Haoyu Wang Zhujun Jiang Xinyu Shan Weisan Pan Xinggang Yang 《Journal of pharmaceutical sciences》2018,107(5):1434-1442
In this study, a bilayer osmotic pump tablet of flurbiprofen (FP) solid dispersions (SDs) was developed to increase the solubility of the poorly soluble drug and controlled drug release at a constant rate. Based on the investigation of thermodynamic properties the drug, the carrier, and the calculation of the solubility parameters, the FP-SD was prepared by hot-melt extrusion technique with the povidone (PVP) VA64 carrier. Then, central composite design-response surface methodology was used to evaluate the influence of factors on the responses. Consequently, PVP VA64 was selected as the carrier for preparing FP-SD. The results of differential scanning calorimetry and X-ray confirmed that FP in FP-SD was in an amorphous state. FTIR indicated that the intermolecular hydrogen bond probably formed between FP and PVP VA64 in FP-SD. Correlation of release profiles to zero-order kinetics was significant (R2 = 0.9939). The mathematical models had good predictability because the deviation was less than 1% between the predicted value and measured value. These results demonstrated that FP-SD osmotic pump tablets successfully increased the solubility of FP and controlled the release of FP at a constant rate. 相似文献
142.
Jianhong Wang Wenwen Zhai Jiaqi Yu Jie Wang Jundong Dai 《Journal of pharmaceutical sciences》2018,107(9):2451-2456
Salvianolic acids and tanshinones both exhibit efficacy in treating idiopathic pulmonary fibrosis (IPF), but their formulation limits their clinical use. This study aimed to prepare the salvianolic acids and tanshinones dry powder for inhalation (SPI) to achieve pulmonary delivery for the treatment of IPF. The variable quantities of salvianolic acids and tanshinones composite powder were optimized using the central composite design-response surface method. Different carriers with various drug-carrier ratios were optimized to prepare SPI. The final optimized formulation of SPI was as follows: InhaLac 230® was selected as the carrier with drug:carrier = 1:6, and the milled lactose InhaLac 400® was added at 5%. The developed SPI characterized with an angle of repose 52.46 ± 1.04°, Carr's index of 34.00 ± 0.50% and showed high lung deposition in vitro, indicating the potential of pulmonary delivery for the treatment of IPF. 相似文献
143.
目的 建立一种测定聚氯乙烯/聚乙烯/聚偏二氯乙烯(PVC/PE/PVDC)固体药用复合硬片PVDC涂布量的方法。方法 裁取10 cm×10 cm的样品5片,将样品先在丙酮中浸泡,分离得到PVC层和PE/PVDC复合层。将PE/PVDC复合层于80℃中干燥2 h后,于23℃放置4 h,精密称定。再将PE/PVDC复合层在四氢呋喃中浸泡,使PVDC层溶解在四氢呋喃溶液中,得到PE膜层,于80℃中干燥2 h后,于23℃放置4 h,精密称定,前后2次差值即为PVDV质量(g)。最后计算PVDC涂布量(以g·m-2表示)。结果 5批样品PVDC涂布量测定结果与标示涂布量均一致,且偏差均在±5%之内。结论 该方法准确、灵敏,适用于PVC/PE/PVDC固体药用复合硬片PVDC涂布量的测定。 相似文献
144.
摘 要 目的:优化盐酸溴己新吸入粉雾剂的处方。方法: 采用冷冻干燥 气流粉碎法制备盐酸溴己新吸入粉雾剂,通过星点设计考察甘露醇(X1),亮氨酸(X2)和泊洛沙姆188(X3)在辅料中的用量对盐酸溴己新吸入粉雾剂的休止角(Y1)、细微粒子剂量(Y2)和空气动力学粒径(Y3)的影响。根据最佳数学模型绘制效应面,通过重叠等高线图确定最优处方。结果:影响因素和考察指标之间存在定量关系,优化处方为甘露醇:亮氨酸:泊洛沙姆188在处方中的比例为2.4∶〖KG-*2〗2.22∶〖KG-*2〗0.05。较优处方的各指标实测值与预测值较接近。结论:采用星点设计 效应面法完成了盐酸溴己新吸入粉雾剂的多目标同步优化。 相似文献
145.
Eliza L.Y. Wong Koonal Shah Annie W.L. Cheung Amy Y.K. Wong Martijn Visser Elly Stolk 《Value in health》2018,21(6):732-741
Background
EQ-5D-5L valuation studies previously reported many inconsistent responses in time trade-off (TTO) data. A number of possible elements, including ordering effects of the valuation tasks, mistakes at the sorting question, and interviewers’ (learning) effects, may contribute to their inconsistency.Objectives
This study aimed to evaluate the effect of two modifications on consistency of TTO data in The Netherlands (NL) and Hong Kong (HK): (1) separating the valuation of the Better than Dead (BTD) and Worse than Dead (WTD) states; and (2) Implementation of feedback (FB) module by offering an opportunity to review TTO responses.Methods
A crossover design with two study arms was used to test the effect of the modifications. In each jurisdiction, six interviewers were involved where half the interviewers started using the standard version, and the other half started with the split version. Each version was switched after every 25 (NL) or 30 (HK) interviews until 400 interviews were completed.Results
In the NL and HK, 404 and 403 respondents participated, respectively. With the use of the FB module, the proportion of respondents with inconsistent responses was lowered from 17.8% to 10.6% (P < 0.001) in NL and from 31.8% to 22.3% (P = 0.003) in HK. The result of separating the valuation of BTD and WTD states was not straightforward because it reduced the inconsistency rate in NL but not in HK.Conclusions
The results support implementation of the FB module to promote the consistency of the data. The separation of the BTD and WTD task is not supported. 相似文献146.
To determine the degree of surface roughness of glass-ionomer cements (GICs) and polyacid-modified resin composite (PAMRC) after polishing and immersion in various foodstuffs. Three tooth-coloured restorative materials were used: a PAMRC (F2000), a conventional glass-ionomer cement (CGIC) (Fuji IX) and a resin-modified glass-ionomer cements (RM-GIC) (Fuji II LC). Disk-shaped specimens were prepared and tested with either a plastics matrix finish or after polishing with wet silicon carbide papers up to 2000-grit. All specimens were immersed in 37 degrees C-distilled water for 1 week, followed by three different foodstuffs (red wine, coffee or tea) for a further 2 weeks. Replicas of specimens were prepared by taking polyvinyl siloxane impressions, casting in epoxy resin, gold sputter-coating and examining using a Field-Emission Scanning Electron Microscope. The polished and matrix finish specimens of F2000 showed many microcracks at low magnification, and eroded surfaces with missing and protruding particles at high magnification in the polished specimens. The surface-polished specimens of Fuji II LC were considerably rougher than the matrix-finish specimens, with large voids and protruding filler particles. The effects of foodstuffs on Fuji II LC and F2000 were not noticeable. The CGIC became noticeably rougher after exposure to coffee and tea. All specimens had the smoothest surface when they were cured against a plastics matrix strip, and all materials had a rougher surface after polishing. None of the foodstuffs produced a perceptible increase in roughness on RM-GIC and PAMRC surfaces, whereas coffee and tea markedly increased the surface roughness of Fuji IX. 相似文献
147.
Bakopoulou A Tsiftsoglou A Galaktidou G Markala D Triviai I Garefis P 《European journal of oral sciences》2007,115(5):397-407
Previous studies have shown that in vitro exposure to single compounds released from composite resins may induce cell death. In the present study the effects of eluates from commercially available composite resins used for direct or indirect restorations were evaluated on the cell cycle progression and type of cell death of cultured WEHI 13 var fibroblasts. Cells exposed to eluates of the materials were assessed for cytotoxicity by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for cell death, for cell cycle profiles by flow cytometry, for caspase-3 biochemically and by immunocytochemistry, and for morphological changes by fluorescence microscopy with acridine orange. The direct composite resin eluates induced extensive apoptosis, followed by secondary necrosis. This was accompanied by cell enlargement, micromultinucleation, chromatin disintegration, cell cycle arrest at different phases, and caspase-3 activation. The composites for indirect restorations were much less cytotoxic at all biological end-points investigated. The findings suggest that composite resins used for direct and indirect dental restorations differ in their cytotoxic potential and their ability to affect basic cellular functions. This underlines the impact of improved polymerization with respect to their biologic behavior. 相似文献
148.
Kelly JR 《Clinical oral implants research》2007,18(Z3):205-217
Objective: Clinical literature was examined for evidence supporting use of CAD/CAM reconstructions and fiber‐reinforced materials. Materials and methods: Potential evidence was identified via databases [PubMed; EMBASE (R) Drugs & Pharmacology; Center for Reviews and Dissemination, University of York; Cochrane Library], hand search of non‐indexed literature, secondary reference searches, and personal contacts with clinical trial PI's. Search terms included: dental restorations; CAD/CAM; CEREC; LAVA; CERCON; Procera; inlay/onlay; dental prosthesis; fiber‐reinforced composite (FRC). Results: Two randomized‐controlled clinical trials were identified as examined in one Cochrane Collaboration review relevant to CAD/CAM inlays. One systematic review of 15 CAD/CAM inlay studies was examined. Six studies were identified of three commercial FRC endodontic posts and eight reported on FRC use for fixed denture prostheses. Fifteen ongoing prospective trials were identified studying CAD/CAM fabricated zirconia‐based prostheses. A total of 76 papers were referenced including those related to use of in vitro measures as evidence. Conclusions: Review of the Cochrane analysis raised concerns that typical RCT protocols may prove insufficient for stratification of confounding variables (patient, practitioner, material) when treatment outcomes are primarily prosthesis‐ or material‐based (not patient‐based, e.g., as in fracture). RCT designs are most straightforward when treatment outcomes are patient‐based (e.g., soft tissue changes). When treatment responses are material‐based, controls also become difficult to define and studies become tests of equivalency/superiority; where well‐stratified cohort designs are likely preferred. Large numbers of independent cohort studies support the use of CAD/CAM ceramic inlay/onlay restorations and crowns but many complications inhibit the application of high‐level systematic review. Except perhaps for fiber‐based endodontic posts, the clinical FRC literature appears insufficient for expert review. Single in vitro measures cannot currently serve as evidence for clinical practice, except in limited cases of simple function (e.g., impression material accuracy). Batteries of in vitro measures are often applied during materials development but cannot substitute for clinical study. 相似文献
149.
目的 考察壳聚糖微球对凝血酶的固定化作用。方法 本研究以壳聚糖微球为载体,以戊二醛为交联剂将凝血酶固定于空白微球上,以固定化凝血酶的活性回收率为指标,采用星点设计-效应面法优化固定凝血酶的条件。结果 试验结果表明,壳聚糖微球固定凝血酶的最优条件是:凝血酶浓度69.32 U·mL-1、戊二醛浓度0.18%、固定化时间1.88 h、固定化pH 7.08,凝血酶的活性回收率为81.55 %。结论 壳聚糖微球对凝血酶的固定化效果良好。 相似文献
150.
目的以绿原酸和菊苣酸及浸出物含量为指标,建立菊苣Cichorium intybus叶最佳干燥方法;优选菊苣叶饮片的最佳炮制工艺,为菊苣叶的开发应用奠定基础。方法建立菊苣叶中绿原酸和菊苣酸含量测定的HPLC方法,测定条件:色谱柱为Agilent Zorbax Eclipse XDB-C18柱(250 mm×4.6 mm,5μm),以乙腈-0.4%磷酸水溶液为流动相梯度洗脱,体积流量为1 mL/min,柱温为30℃,检测波长为334 nm;采用绿原酸和菊苣酸及浸出物多指标确定菊苣叶最佳干燥方法;采用星点设计-响应面法对菊苣叶切制段长、干燥温度、干燥时间进行考察,以绿原酸、菊苣酸、浸出物含量及色度值、饮片外观性状等按照权重计分为评价指标并进行综合分析。结果菊苣叶最佳干燥方法为远红外干燥法;菊苣叶饮片炮制工艺条件为切制段长7 mm、干燥温度为50℃、干燥时间为17 h。结论优选出的菊苣叶炮制工艺综合评分较高,不仅最大限度保留有效成分,而且饮片色泽好,可重复性强,工艺稳定可靠。 相似文献