全文获取类型
收费全文 | 3625篇 |
免费 | 158篇 |
国内免费 | 6篇 |
专业分类
耳鼻咽喉 | 74篇 |
儿科学 | 150篇 |
妇产科学 | 39篇 |
基础医学 | 287篇 |
口腔科学 | 162篇 |
临床医学 | 254篇 |
内科学 | 587篇 |
皮肤病学 | 70篇 |
神经病学 | 279篇 |
特种医学 | 228篇 |
外科学 | 716篇 |
综合类 | 119篇 |
预防医学 | 151篇 |
眼科学 | 238篇 |
药学 | 233篇 |
中国医学 | 14篇 |
肿瘤学 | 188篇 |
出版年
2023年 | 23篇 |
2022年 | 60篇 |
2021年 | 128篇 |
2020年 | 49篇 |
2019年 | 75篇 |
2018年 | 118篇 |
2017年 | 78篇 |
2016年 | 105篇 |
2015年 | 90篇 |
2014年 | 130篇 |
2013年 | 182篇 |
2012年 | 275篇 |
2011年 | 268篇 |
2010年 | 151篇 |
2009年 | 142篇 |
2008年 | 199篇 |
2007年 | 187篇 |
2006年 | 151篇 |
2005年 | 173篇 |
2004年 | 142篇 |
2003年 | 120篇 |
2002年 | 141篇 |
2001年 | 79篇 |
2000年 | 70篇 |
1999年 | 58篇 |
1998年 | 26篇 |
1997年 | 21篇 |
1996年 | 11篇 |
1995年 | 15篇 |
1993年 | 16篇 |
1992年 | 33篇 |
1991年 | 43篇 |
1990年 | 31篇 |
1989年 | 41篇 |
1988年 | 33篇 |
1987年 | 35篇 |
1986年 | 21篇 |
1985年 | 16篇 |
1984年 | 21篇 |
1983年 | 20篇 |
1981年 | 17篇 |
1979年 | 14篇 |
1977年 | 19篇 |
1976年 | 12篇 |
1975年 | 18篇 |
1974年 | 15篇 |
1973年 | 14篇 |
1972年 | 21篇 |
1971年 | 12篇 |
1969年 | 14篇 |
排序方式: 共有3789条查询结果,搜索用时 15 毫秒
71.
Purpose
To provide normal macular thickness measurements using Spectral Domain Optical Coherence Tomography (SDOCT, Copernicus, Optopol Technologies, Zawierci, Poland).Methods
Fifty-eight eyes of 58 healthy subjects were included in this prospective study. All subjects had comprehensive ophthalmic examination including best-corrected visual acuity (BCVA). All the subjects underwent Copernicus SDOCT. Central foveal thickness (CFT) and photoreceptor layer (PRL) thickness were measured and expressed as mean and standard deviation. Mean retinal thickness for each of the 9 regions defined in the Early Treatment Diabetic Retinopathy Study was reported. The data were compared with published literature in Indians using Stratus and Spectralis OCTs to assess variation in instrument measurements.Results
The mean CFT in the study sample was 173.8 ± 18.16 microns (131–215 microns) and the mean PRL thickness was 65.48 ± 4.23 microns (56–74 microns). No significant difference (p = 0.148) was found between CFT measured automated (179.28 ± 22 microns) and manually (173.83 ± 18.1 microns). CFT was significantly lower in women (167.62 ± 16.36 microns) compared to men (180.03 ± 18 microns) (p = 0.008). Mean retinal thickness reported in this study was significantly different from published literature using Stratus OCT and Spectralis OCT.Conclusion
We report the normal mean retinal thickness in central 1 mm area to be between 138 and 242 microns in Indian population using Copernicus SDOCT. We suggest that different OCT instruments cannot be used interchangeably for the measurement of macular thickness as they vary in segmentation algorithms. 相似文献72.
Jan H Beumer Venkateswaran C Pillai Robert A Parise Susan M Christner Brian F Kiesel Michelle A Rudek Raman Venkataramanan 《British journal of clinical pharmacology》2015,80(5):1097-1108
Aim
Inducers and inhibitors of CYP3A, such as ritonavir and efavirenz, may be used as part of the highly active antiretroviral therapy (HAART) to treat HIV patients. HIV patients with chronic myeloid leukemia or gastrointestinal stromal tumour may need imatinib, a CYP3A4 substrate with known exposure response–relationships. Administration of imatinib to patients on ritonavir or efavirenz may result in altered imatinib exposure leading to increased toxicity or failure of therapy, respectively. We used primary human hepatocyte cultures to evaluate the magnitude of interaction between imatinib and ritonavir/efavirenz.Methods
Hepatocytes were pre-treated with vehicle, ritonavir, ketoconazole, efavirenz or rifampicin, and the metabolism of imatinib was characterized over time. Concentrations of imatinib and metabolite were quantitated in combined lysate and medium, using LC-MS.Results
The predicted changes in imatinib CLoral (95% CI) with ketoconazole, ritonavir, rifampicin and efavirenz were 4.0-fold (0, 9.2) lower, 2.8-fold (0.04, 5.5) lower, 2.9-fold (2.2, 3.5) higher and 2.0-fold (0.42, 3.5) higher, respectively. These predictions were in good agreement with clinical single dose drug–drug interaction studies, but not with reports of imatinib interactions at steady-state. Alterations in metabolism were similar after acute or chronic imatinib exposure.Conclusions
In vitro human hepatocytes predicted increased clearance of imatinib with inducers and decreased clearance with inhibitors of CYP enzymes. The impact of HAART on imatinib may depend on whether it is being initiated or has already been dosed chronically in patients. Therapeutic drug monitoring may have a role in optimizing imatinib therapy in this patient population. 相似文献73.
Parth Makker MD Moussa Saleh MD Aditi S. Vaishnav MBBS Kristie M. Coleman RN Stuart Beldner MD Haisam Ismail MD Nikhil Sharma MD Ram Jadonath MD Bruce Goldner MD Raman Mitra MD PhD Laurence Epstein MD Roy John MD Stavros E. Mountantonakis MD 《Journal of cardiovascular electrophysiology》2021,32(6):1658-1664
74.
Sequencing of 3-O sulfate containing heparin decasaccharides with a partial antithrombin III binding site 下载免费PDF全文
Shriver Z Raman R Venkataraman G Drummond K Turnbull J Toida T Linhardt R Biemann K Sasisekharan R 《Proceedings of the National Academy of Sciences of the United States of America》2000,97(19):10359-10364
Heparin- and heparan sulfate-like glycosaminoglycans (HLGAGs) represent an important class of molecules that interact with and modulate the activity of growth factors, enzymes, and morphogens. Of the many biological functions for this class of molecules, one of its most important functions is its interaction with antithrombin III (AT-III). AT-III binding to a specific heparin pentasaccharide sequence, containing an unusual 3-O sulfate on a N-sulfated, 6-O sulfated glucosamine, increases 1,000-fold AT-III's ability to inhibit specific proteases in the coagulation cascade. In this manner, HLGAGs play an important biological and pharmacological role in the modulation of blood clotting. Recently, a sequencing methodology was developed to further structure-function relationships of this important class of molecules. This methodology combines a property-encoded nomenclature scheme to handle the large information content (properties) of HLGAGs, with matrix-assisted laser desorption ionization MS and enzymatic and chemical degradation as experimental constraints to rapidly sequence picomole quantities of HLGAG oligosaccharides. Using the above property-encoded nomenclature-matrix-assisted laser desorption ionization approach, we found that the sequence of the decasaccharide used in this study is DeltaU(2S)H(NS,6S)I(2S)H(NS, 6S)I(2S)H(NS,6S)IH(NAc,6S)GH(NS,3S,6S) (+/-DDD4-7). We confirmed our results by using integral glycan sequencing and one-dimensional proton NMR. Furthermore, we show that this approach is flexible and is able to derive sequence information on an oligosaccharide mixture. Thus, this methodology will make possible both the analysis of other unusual sequences in HLGAGs with important biological activity as well as provide the basis for the structural analysis of these pharamacologically important group of heparin/heparan sulfates. 相似文献
75.
Joachim G. Eichhorn MD Frederick R. Long MD Claudia Jourdan MD Johannes T. Heverhagen MD PhD Sharon L. Hill ARNP Subha V. Raman MD John P. Cheatham MD 《Catheterization and cardiovascular interventions》2008,72(4):544-551
Objective : To evaluate varying CT settings to visualize pediatric vascular stents in comparison to digital angiography (DA). Background : There is a great clinical interest in substituting noninvasive methods to follow up children with congenital heart disease after interventional treatment. Materials and Methods : CT studies in small children with transcatheter placed stents were reviewed, retrospectively. Furthermore, eight stents were implanted in tubes and partially obstructed. CT exams were performed on varying scanners (4 up to 64 slices) with corresponding tube settings. The effects of dose on image quality were evaluated regarding stent size, strut thickness, and in‐stent stenoses in comparison to DA. Results : Fourteen children with 28 implanted stents were identified. Significant differences between higher and lower radiation settings were not found, corresponding with the phantom, where moderate tube setting showed the best results. In vitro, there was an improvement with increasing number of detector rows, which resulted in a decrease of stent strut overestimation (295% down to 201%; P < 0.0001) and a better agreement with DA measurements for mild (78% up to 91%; P = 0.003) and moderate in‐stent stenoses (80% up to 99%; P = 0.0001). Conclusion : Higher radiation exposure settings did not improve image quality, suggesting that the exams could be performed at a lower radiation dose. © 2008 Wiley‐Liss, Inc. 相似文献
76.
We report B.R.B., a bilingual Turkish–English speaker with deep dysphasia. B.R.B. shows the typical pattern of semantic errors in repetition with effects of lexicality and imageability on performance in both languages. The question we asked is whether language type (Turkish or English) or language status—that is, first acquired (L1) or second acquired (L2)—has a greater impact on performance. Results showed that repetition in L1 (Turkish) was better than that in L2 (English). We also observed effects of language status on oral reading, writing to dictation, and naming (spoken and written) with greater impairment to repetition than other tasks in both languages. An additional finding was that spoken-word translation in both directions was worse than written-word translation, and word class had an effect on translation from L1 to L2. We argue that interactive activation models of deep dysphasia could explain deep dysphasia in bilingual speakers and interactions between task and language, if the weighted connections that support language processing in L2 are assumed to be weaker, thus causing rapid phonological decay to have more impact on task performance in L2. Implications of the results for models of bilingual language processing are also considered. 相似文献
77.
Henry W. Murray Yunhua Zhang Yan Zhang Vanitha S. Raman Steven G. Reed Xiaojing Ma 《Infection and immunity》2013,81(7):2318-2326
In livers of susceptible but self-curing C57BL/6 mice, intracellular Leishmania donovani infection enhanced Toll-like receptor 4 (TLR4) and TLR2 gene expression. In the liver, infected TLR4−/− mice showed reduced gamma interferon (IFN-γ), tumor necrosis factor (TNF), and inducible nitric oxide synthase (iNOS) mRNA expression, higher-level and slowly resolving infection, delayed granuloma formation, and little response to low-dose chemotherapy; in serum, the ratio of IFN-γ to interleukin 10 (IL-10) activity was decreased by 50%. In contrast, in TLR2−/− mice, control of liver infection, parasite killing, and granuloma assembly were accelerated and chemotherapy''s efficacy enhanced. In livers of infected TLR2−/− mice, mRNA expression was not increased for inflammatory cytokines or iNOS or decreased for IL-10; however, the serum IFN-γ/IL-10 ratio was increased 6.5-fold and minimal responses to IL-10 receptor blockade suggested downregulated IL-10. In established infection in wild-type mice, blockading TLR2 induced parasite killing and triggering TLR4 strengthened resistance and promoted chemotherapy''s effect. Thus, in experimental L. donovani infection in the liver, TLR4 signaling upregulates and TLR2 signaling downregulates macrophage antileishmanial activity, making both receptors potential therapeutic targets in visceral leishmaniasis for engagement (TLR4) or blockade (TLR2). 相似文献
78.
Gupta Manisha Krishan Pawan Kaur Amarjot Arora Sandeep Trehanpati Nirupma Singh Thakur Gurjeet Bedi Onkar 《Inflammation research》2021,70(7):765-776
Inflammation Research - Non-alcoholic fatty liver disease (NAFLD) is a multifaceted disease allied with various metabolic disorders, obesity and dysbiosis. Gut microbiota plays an influential role... 相似文献
79.
Bo Zhang Yan Zhou Nan Lin Rebecca F. Lowdon Chibo Hong Raman P. Nagarajan Jeffrey B. Cheng Daofeng Li Michael Stevens Hyung Joo Lee Xiaoyun Xing Jia Zhou Vasavi Sundaram GiNell Elliott Junchen Gu Taoping Shi Philippe Gascard Mahvash Sigaroudinia Thea D. Tlsty Theresa Kadlecek Arthur Weiss Henriette O’Geen Peggy J. Farnham Cécile L. Maire Keith L. Ligon Pamela A.F. Madden Angela Tam Richard Moore Martin Hirst Marco A. Marra Baoxue Zhang Joseph F. Costello Ting Wang 《Genome research》2013,23(9):1522-1540
80.
Subramaniam Puvaneswary Hanumantha Rao Balaji Raghavendran Nurul Syuhada Ibrahim Malliga Raman Murali Azhar Mahmood Merican T. Kamarul 《International journal of medical sciences》2013,10(12):1608-1614
The objective of this study was to compare the morphological and chemical composition of bone graft (BG) and coral graft (CG) as well as their osteogenic differentiation potential using rabbit mesenchymal stem cells (rMSCs) in vitro. SEM analysis of BG and CG revealed that the pores in these grafts were interconnected, and their micro-CT confirmed pore sizes in the range of 107-315 µm and 103-514 µm with a total porosity of 92% and 94%, respectively. EDS analysis indicated that the level of calcium in CG was relatively higher than that in BG. FTIR of BG and CG confirmed the presence of functional groups corresponding to carbonyl, aromatic, alkyl, and alkane groups. XRD results revealed that the phase content of the inorganic layer comprised highly crystalline form of calcium carbonate and carbon. Atomic force microscopy analysis showed CG had better surface roughness compared to BG. In addition, significantly higher levels of osteogenic differentiation markers, namely, alkaline phosphatase (ALP), Osteocalcin (OC) levels, and Osteonectin and Runx2, Integrin gene expression were detected in the CG cultures, when compared with those in the BG cultures. In conclusion, our results demonstrate that the osteogenic differentiation of rMSCs is relatively superior in coral graft than in bone graft culture system. 相似文献