全文获取类型
收费全文 | 25823篇 |
免费 | 1415篇 |
国内免费 | 157篇 |
专业分类
耳鼻咽喉 | 319篇 |
儿科学 | 657篇 |
妇产科学 | 586篇 |
基础医学 | 3175篇 |
口腔科学 | 604篇 |
临床医学 | 1942篇 |
内科学 | 7399篇 |
皮肤病学 | 811篇 |
神经病学 | 2050篇 |
特种医学 | 652篇 |
外科学 | 3596篇 |
综合类 | 137篇 |
一般理论 | 10篇 |
预防医学 | 1820篇 |
眼科学 | 447篇 |
药学 | 1382篇 |
中国医学 | 85篇 |
肿瘤学 | 1723篇 |
出版年
2023年 | 191篇 |
2022年 | 435篇 |
2021年 | 987篇 |
2020年 | 429篇 |
2019年 | 871篇 |
2018年 | 1011篇 |
2017年 | 578篇 |
2016年 | 580篇 |
2015年 | 665篇 |
2014年 | 1070篇 |
2013年 | 1232篇 |
2012年 | 1933篇 |
2011年 | 1985篇 |
2010年 | 1075篇 |
2009年 | 1027篇 |
2008年 | 1519篇 |
2007年 | 1558篇 |
2006年 | 1400篇 |
2005年 | 1370篇 |
2004年 | 1308篇 |
2003年 | 1157篇 |
2002年 | 1143篇 |
2001年 | 427篇 |
2000年 | 450篇 |
1999年 | 387篇 |
1998年 | 185篇 |
1997年 | 160篇 |
1996年 | 144篇 |
1995年 | 102篇 |
1994年 | 95篇 |
1993年 | 87篇 |
1992年 | 199篇 |
1991年 | 166篇 |
1990年 | 164篇 |
1989年 | 146篇 |
1988年 | 140篇 |
1987年 | 119篇 |
1986年 | 107篇 |
1985年 | 92篇 |
1984年 | 84篇 |
1983年 | 50篇 |
1982年 | 34篇 |
1981年 | 31篇 |
1980年 | 29篇 |
1979年 | 57篇 |
1976年 | 31篇 |
1975年 | 48篇 |
1974年 | 44篇 |
1972年 | 30篇 |
1969年 | 27篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Jo JA Blasi A Valladares EM Juarez R Baydur A Khoo MC 《Annals of biomedical engineering》2007,35(8):1425-1443
Using the Volterra–Wiener approach, we employed a minimal model to quantitatively characterize the linear and nonlinear effects
of respiration (RCC) and arterial blood pressure (ABR) on heart rate variability (HRV) in normal controls and subjects with
moderate-to-severe obstructive sleep apnea syndrome (OSAS). Respiration, R–R interval (RRI), blood pressure (BP) and other
polysomnographic variables were recorded in eight normal controls and nine OSAS subjects in wakefulness, Stage 2 and rapid
eye-movement sleep. To increase respiratory and cardiovascular variability, a preprogrammed ventilator delivered randomly
timed inspiratory pressures that were superimposed on a baseline continuous positive airway pressure. Except for lower resting
RRI in OSAS subjects, summary statistical measures of RRI and BP and their variabilities were similar in controls and OSAS.
In contrast, RCC and ABR gains were significantly lower in OSAS. Nonlinear ABR gain and the interaction between respiration
and blood pressure in modulating RRI were substantially reduced in OSAS. ABR gain increased during sleep in controls but remained
unchanged in OSAS. These findings suggest that normotensive OSAS subjects have impaired daytime parasympathetic and sympathetic
function. Nonlinear minimal modeling of HRV provides a useful, insightful, and comprehensive approach for the detection and
assessment of abnormal autonomic function in OSAS.
Supported by NIH Grants HL-58725, EB-001978, and M01 RR-43 相似文献
992.
The tumor gene survivin is highly expressed in adult renal tubular cells: implications for a pathophysiological role in the kidney 下载免费PDF全文
Lechler P Wu X Bernhardt W Campean V Gastiger S Hackenbeck T Klanke B Weidemann A Warnecke C Amann K Engehausen D Willam C Eckardt KU Rödel F Wiesener MS 《The American journal of pathology》2007,171(5):1483-1498
The inhibitor of apoptosis protein survivin is of critical importance for regulation of cellular division and survival. Published data point to a restricted function of survivin in embryonic development and cancer; thus survivin has been broadly proposed as an ideal molecular target for specific anti-cancer therapy. In contrast to this paradigm, we report here broad expression of survivin in adult differentiated tissues, as demonstrated at the mRNA and protein levels. Focusing on the kidney, survivin is strongly expressed in proximal tubuli, particularly at the apical membrane, which can be verified in rat, mouse, and human kidneys. In the latter, survivin expression seems to be even stronger in proximal tubuli than in adjacent cancerous tissue. Primary and immortalized human renal tubular cells also showed high levels of survivin protein expression, and RNA interference resulted in a partial G(2)/M arrest of the cell cycle and increased rate of apoptosis. In conclusion, survivin may be of importance for renal pathophysiology and pathology. The predominant apical expression of survivin may indicate a further, yet unknown, function. Interventional strategies to inhibit survivin's function in malignancy need to be carefully (re)evaluated for renal side effects, as well as for other possible organ dysfunctions. 相似文献
993.
994.
Posner MR Hershock DM Blajman CR Mickiewicz E Winquist E Gorbounova V Tjulandin S Shin DM Cullen K Ervin TJ Murphy BA Raez LE Cohen RB Spaulding M Tishler RB Roth B Viroglio Rdel C Venkatesan V Romanov I Agarwala S Harter KW Dugan M Cmelak A Markoe AM Read PW Steinbrenner L Colevas AD Norris CM Haddad RI;TAX Study Group 《The New England journal of medicine》2007,357(17):1705-1715
995.
López-Cano M Rodríguez-Navarro J Rodríguez-Baeza A Armengol-Carrasco M Susín A 《Computers in biology and medicine》2007,37(9):1321-1326
A suitable dynamic 3D model that allows the simulation of the inguinal region with real-time performance on a personal computer was developed. A geometric model adjusted to real data was created by means of semiautomatic contour segmentation of anatomic units from the visible human project and data generated from classical anatomic information. A dynamic model included converting muscular units from their continuous geometric representation into a set of voxels and then real-time interaction and performance. The current implementation enables deformation of the realistic model associated with pushing and stretching interaction, allowing immersion in the anatomy of the inguinal structures. The model does not allow simulation of surgical interventions. 相似文献
996.
Maria Isabel Mas-Fuster Amelia Ramon-Lopez Javier Lacueva Patricio Más-Serrano Ricardo Nalda-Molina 《Journal of pharmaceutical sciences》2018,107(2):764-769
The purpose of this study was to evaluate the area under the concentration-time curve (AUC) ratio as an optimal indicator of the pharmacokinetic advantage during hyperthermic intraperitoneal perioperative chemotherapy. The impact on the AUC ratio on the variables related to the calculation of systemic drug exposure, instillation time, and peripheral drug distribution was evaluated through simulations as well as through a retrospective analysis of studies published in the literature. Both model simulations and the retrospective analysis showed that the 3 variables evaluated had an impact on the AUC ratio value if the complete systemic exposure was not fully considered. However, when that complete systemic exposure was considered, none of these variables affected the AUC ratio value. AUC ratio is not a characteristic parameter of a drug if the calculated systemic drug exposure is not complete. Thus, AUC ratio is not valid for comparing the pharmacokinetic advantage of 2 drugs, and it should not be employed to prove whether a drug can be used in hyperthermic intraperitoneal perioperative chemotherapy safely with regard to toxicity. As an alternative, the study of the absorption rate constant and the bioavailability are proposed as the true and independent parameters that reflect the amount of drug absorbed. 相似文献
997.
Verônica M. Couto Maria J. Prieto Daniela E. Igartúa Daniela A. Feas Lígia N.M. Ribeiro Camila M.G. Silva Simone R. Castro Viviane A. Guilherme Darlene D. Dantzger Daisy Machado Silvia del V. Alonso Eneida de Paula 《Journal of pharmaceutical sciences》2018,107(9):2411-2419
Administration of local anesthetics is one of the most effective pain control techniques for postoperative analgesia. However, anesthetic agents easily diffuse into the injection site, limiting the time of anesthesia. One approach to prolong analgesia is to entrap local anesthetic agents in nanostructured carriers (e.g., liposomes). Here, we report that using an ammonium sulphate gradient was the best strategy to improve the encapsulation (62.6%) of dibucaine (DBC) into liposomes. Light scattering and nanotracking analyses were used to characterize vesicle properties, such as, size, polydispersity, zeta potentials, and number. In vitro kinetic experiments revealed the sustained release of DBC (50% in 7 h) from the liposomes. In addition, in vitro (3T3 cells in culture) and in vivo (zebrafish) toxicity assays revealed that ionic-gradient liposomes were able to reduce DBC cyto/cardiotoxicity and morphological changes in zebrafish larvae. Moreover, the anesthesia time attained after infiltrative administration in mice was longer with encapsulated DBC (27 h) than that with free DBC (11 h), at 320 μM (0.012%), confirming it as a promising long-acting liposome formulation for parenteral drug administration of DBC. 相似文献
998.
Adolfo Quiñones‐Lombraña G. Ekin Atilla‐Gokcumen Javier G. Blanco 《Biopharmaceutics & drug disposition》2018,39(6):315-318
Loxoprofen is an anti‐inflammatory drug that requires bioactivation into the trans‐OH metabolite to exert pharmacological activity. Evidence suggests that carbonyl reductase 1 (CBR1) is important during the bioactivation of loxoprofen. This study examined the impact of the functional single nucleotide polymorphism CBR1 rs9024 on the bioactivation of loxoprofen in a collection of human liver samples. The synthesis ratios of trans‐OH loxoprofen/cis‐OH loxoprofen were 33% higher in liver cytosols from donors homozygous for the CBR1 rs9024 G allele in comparison with the ratios in samples from donors with heterozygous GA genotypes. Complementary studies examined the impact of CBR1 rs9024 on the bioactivation of loxoprofen in lymphoblastoid cell lines. CBR1 rs9024 genotype status impacts the synthesis of the bioactive trans‐OH metabolite of loxoprofen in human liver. 相似文献
999.
Purpose
FCGRT encodes the alpha-chain component of the neonatal Fc receptor (FcRn). FcRn is critical for the trafficking of endogenous and exogenous IgG molecules and albumin in various tissues. Few regulators of FcRn expression have been identified. We investigated the epigenetic regulation of FcRn by two microRNAs (hsa-miR-3181 and hsa-miR-3136-3p) acting on FCGRT.Methods
The binding of candidate microRNAs to the 3′-untranslated region of FCGRT was evaluated using luciferase reporter constructs in CHO cells. The effect of microRNAs on FCGRT mRNA and FcRn protein expression was evaluated using specific microRNA mimics and inhibitor transfections in A549, HEK293 and HepG2 cells.Results
Hsa-miR-3181 mimic reduced luciferase reporter activity by 70.1% (10 nM, P <?0.0001). In A549, HEK293 and HepG2 cells, hsa-miR-3181 decreased FCGRT mRNA expression (48.6%, 51.3% and 43.5% respectively, 25 nM, P <?0.05). The hsa-miR-3181 mimic decreased the expression of FcRn protein by 40% after 48 h (25 nM, P <?0.001). The mature form of hsa-miR-3181 was detected in samples of human liver.Conclusions
These data suggest that hsa-miR-3181 is an epigenetic regulator of FCGRT expression. The identification of this regulator of FCGRT may provide insights into a potential determinant of interindividual variability in FcRn expression.1000.
Alejandro Pérez-Pitarch Rafael Ferriols-Lisart Gerardo Aguilar Carlos Ezquer-Garín F. Javier Belda Beatriz Guglieri-López 《International journal of antimicrobial agents》2018,51(1):115-121