全文获取类型
收费全文 | 188370篇 |
免费 | 1853篇 |
国内免费 | 35篇 |
专业分类
耳鼻咽喉 | 1239篇 |
儿科学 | 7138篇 |
妇产科学 | 3239篇 |
基础医学 | 18106篇 |
口腔科学 | 1722篇 |
临床医学 | 13773篇 |
内科学 | 33141篇 |
皮肤病学 | 862篇 |
神经病学 | 17698篇 |
特种医学 | 9300篇 |
外国民族医学 | 2篇 |
外科学 | 30607篇 |
综合类 | 2645篇 |
一般理论 | 13篇 |
预防医学 | 19180篇 |
眼科学 | 3347篇 |
药学 | 10503篇 |
中国医学 | 647篇 |
肿瘤学 | 17096篇 |
出版年
2023年 | 61篇 |
2022年 | 124篇 |
2021年 | 391篇 |
2020年 | 237篇 |
2019年 | 356篇 |
2018年 | 22280篇 |
2017年 | 17627篇 |
2016年 | 19784篇 |
2015年 | 1268篇 |
2014年 | 1271篇 |
2013年 | 1464篇 |
2012年 | 7930篇 |
2011年 | 21912篇 |
2010年 | 19341篇 |
2009年 | 11980篇 |
2008年 | 20164篇 |
2007年 | 22485篇 |
2006年 | 1280篇 |
2005年 | 2916篇 |
2004年 | 4044篇 |
2003年 | 4973篇 |
2002年 | 3040篇 |
2001年 | 426篇 |
2000年 | 560篇 |
1999年 | 325篇 |
1998年 | 375篇 |
1997年 | 334篇 |
1996年 | 179篇 |
1995年 | 201篇 |
1994年 | 208篇 |
1993年 | 137篇 |
1992年 | 155篇 |
1991年 | 176篇 |
1990年 | 214篇 |
1989年 | 173篇 |
1988年 | 134篇 |
1987年 | 103篇 |
1986年 | 89篇 |
1985年 | 96篇 |
1984年 | 93篇 |
1983年 | 81篇 |
1982年 | 115篇 |
1981年 | 69篇 |
1980年 | 105篇 |
1979年 | 64篇 |
1978年 | 62篇 |
1974年 | 46篇 |
1938年 | 65篇 |
1932年 | 56篇 |
1930年 | 48篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
1.
2.
There is a sharp difference in how one views TCR structure–function–behaviour dependent on whether its recognition of major histocompatibility complex‐encoded restriction elements (R) is germline selected or somatically generated. The generally accepted or Standard model is built on the assumption that recognition of R is by the V regions of the αβ TCR, which is not driven by allele specificity, whereas the competing model posits that recognition of R is allele‐specific. The establishing of allele‐specific recognition of R by the TCR would rule out the Standard model and clear the road to a consideration of a competing construct, the Tritope model. Here, the case for allele‐specific recognition (germline selected) is detailed making it obvious that the Standard model is untenable. 相似文献
3.
Seyed Mehdi BagheriMofidi Majid Pouladian Seyed Behnamedin Jameie Ali Abbaspour Tehrani-Fard 《Australasian physical & engineering sciences in medicine / supported by the Australasian College of Physical Scientists in Medicine and the Australasian Association of Physical Sciences in Medicine》2016,39(3):717-726
Magnetic field generated by neuronal activity could alter magnetic resonance imaging (MRI) signals but detection of such signal is under debate. Previous researches proposed that magnitude signal change is below current detectable level, but phase signal change (PSC) may be measurable with current MRI systems. Optimal imaging parameters like echo time, voxel size and external field direction, could increase the probability of detection of this small signal change. We simulate a voxel of cortical column to determine effect of such parameters on PSC signal. We extended a laminar network model for somatosensory cortex to find neuronal current in each segment of pyramidal neurons (PN). 60,000 PNs of simulated network were positioned randomly in a voxel. Biot–savart law applied to calculate neuronal magnetic field and additional phase. The procedure repeated for eleven neuronal arrangements in the voxel. PSC signal variation with the echo time and voxel size was assessed. The simulated results show that PSC signal increases with echo time, especially 100/80 ms after stimulus for gradient echo/spin echo sequence. It can be up to 0.1 mrad for echo time = 175 ms and voxel size = 1.48 × 1.48 × 2.18 mm3. With echo time less than 25 ms after stimulus, it was just acquired effects of physiological noise on PSC signal. The absolute value of the signal increased with decrease of voxel size, but its components had complex variation. External field orthogonal to local surface of cortex maximizes the signal. Expected PSC signal for tactile detection in the somatosensory cortex increase with echo time and have no oscillation. 相似文献
4.
5.
6.
7.
Wai Man Mandy Chan Yik Weng Yew Thiam Seng Colin Theng Choon Fong Liew Hazel H Oon 《Singapore medical journal》2020,61(4):194
INTRODUCTIONPsoriasis is a chronic inflammatory condition that affects the skin and joints, and is associated with cardiovascular risk factors, including metabolic syndrome (MetS). We aimed to assess the prevalence of MetS in patients with psoriasis and determine whether there was a correlation between psoriasis severity and MetS in a Singapore population.METHODSThis was a cross-sectional study of patients with psoriasis, aged 18–69 years, who attended a tertiary dermatology referral centre in Singapore from October 2007 to February 2009. Fasting glucose, lipids, blood pressure, Psoriasis Area and Severity Index, and body mass index were measured. MetS was diagnosed in the presence of three or more criteria of the modified National Cholesterol Education Program Adult Treatment Panel III.RESULTSAmong 338 patients with psoriasis, there were 238 (70.4%) men and 100 (29.6%) women, who were Chinese (n = 228; 67.5%), Malay (n = 52; 15.4%) and Indian (n = 58; 17.2%). The prevalence of MetS was 45.1%. MetS was 44% more prevalent in patients older than 50 years (p = 0.02). Malay patients with psoriasis were significantly more likely to have hypertriglyceridaemia, elevated fasting plasma glucose and abdominal obesity. There was no significant correlation between psoriasis severity and risk of MetS.CONCLUSIONThe prevalence of MetS in patients with psoriasis in Singapore was 45.1%, or nearly threefold higher than the Singapore general population. Patients with psoriasis should be screened yearly for MetS and any modifiable cardiovascular risk factors should be actively controlled. 相似文献
8.
9.
N. S. Hari Narayana Moorthy Sergio F. Sousa Maria J. Ramos Pedro A. Fernandes 《Medicinal chemistry research》2016,25(7):1340-1357
Farnesyltransferase (FTase) is one of the prenyltransferase family enzymes that catalyse the transfer of 15-membered isoprenoid (farnesyl) moiety to the cysteine of CAAX motif-containing proteins including Rho and Ras family of G proteins. Inhibitors of FTase act as drugs for cancer, malaria, progeria and other diseases. In the present investigation, we have developed two structure-based pharmacophore models from protein–ligand complex (3E33 and 3E37) obtained from the protein data bank. Molecular dynamics (MD) simulations were performed on the complexes, and different conformers of the same complex were generated. These conformers were undergone protein–ligand interaction fingerprint (PLIF) analysis, and the fingerprint bits have been used for structure-based pharmacophore model development. The PLIF results showed that Lys164, Tyr166, TrpB106 and TyrB361 are the major interacting residues in both the complexes. The RMSD and RMSF analyses on the MD-simulated systems showed that the absence of FPP in the complex 3E37 has significant effect in the conformational changes of the ligands. During this conformational change, some interactions between the protein and the ligands are lost, but regained after some simulations (after 2 ns). The structure-based pharmacophore models showed that the hydrophobic and acceptor contours are predominantly present in the models. The pharmacophore models were validated using reference compounds, which significantly identified as HITs with smaller RMSD values. The developed structure-based pharmacophore models are significant, and the methodology used in this study is novel from the existing methods (the original X-ray crystallographic coordination of the ligands is used for the model building). In our study, along with the original coordination of the ligand, different conformers of the same complex (protein–ligand) are used. It concluded that the developed methodology is significant for the virtual screening of novel molecules on different targets. 相似文献
10.
Paul J. Devlin Brian W. McCrindle James K. Kirklin Eugene H. Blackstone William M. DeCampli Christopher A. Caldarone Ali Dodge-Khatami Pirooz Eghtesady James M. Meza Peter J. Gruber Kristine J. Guleserian Bahaaladin Alsoufi Linda M. Lambert James E. OBrien Erle H. Austin Jeffrey P. Jacobs Tara Karamlou 《The Journal of thoracic and cardiovascular surgery》2019,157(2):684-695.e8