全文获取类型
收费全文 | 5544篇 |
免费 | 440篇 |
国内免费 | 100篇 |
专业分类
耳鼻咽喉 | 47篇 |
儿科学 | 150篇 |
妇产科学 | 141篇 |
基础医学 | 649篇 |
口腔科学 | 139篇 |
临床医学 | 539篇 |
内科学 | 1139篇 |
皮肤病学 | 139篇 |
神经病学 | 324篇 |
特种医学 | 167篇 |
外科学 | 767篇 |
综合类 | 451篇 |
预防医学 | 529篇 |
眼科学 | 77篇 |
药学 | 373篇 |
5篇 | |
中国医学 | 196篇 |
肿瘤学 | 252篇 |
出版年
2023年 | 39篇 |
2022年 | 108篇 |
2021年 | 170篇 |
2020年 | 122篇 |
2019年 | 144篇 |
2018年 | 135篇 |
2017年 | 156篇 |
2016年 | 101篇 |
2015年 | 145篇 |
2014年 | 218篇 |
2013年 | 301篇 |
2012年 | 350篇 |
2011年 | 337篇 |
2010年 | 263篇 |
2009年 | 256篇 |
2008年 | 279篇 |
2007年 | 313篇 |
2006年 | 330篇 |
2005年 | 245篇 |
2004年 | 209篇 |
2003年 | 213篇 |
2002年 | 163篇 |
2001年 | 143篇 |
2000年 | 163篇 |
1999年 | 117篇 |
1998年 | 54篇 |
1997年 | 39篇 |
1996年 | 34篇 |
1995年 | 36篇 |
1994年 | 23篇 |
1993年 | 34篇 |
1992年 | 84篇 |
1991年 | 66篇 |
1990年 | 64篇 |
1989年 | 61篇 |
1988年 | 54篇 |
1987年 | 62篇 |
1986年 | 39篇 |
1985年 | 46篇 |
1984年 | 38篇 |
1983年 | 48篇 |
1982年 | 25篇 |
1981年 | 23篇 |
1980年 | 16篇 |
1979年 | 27篇 |
1978年 | 19篇 |
1976年 | 24篇 |
1974年 | 21篇 |
1973年 | 16篇 |
1971年 | 15篇 |
排序方式: 共有6084条查询结果,搜索用时 15 毫秒
41.
Gutiérrez-Puente Y Tari AM Ford RJ Tamez-Guerra R Mercado-Hernandez R Santoyo-Stephano M Lopez-Berestein G 《Leukemia & lymphoma》2003,44(11):1979-1985
A P-ethoxy oligonucleotide (oligo), 20 bases long and specific for the translation initiation site of human Bcl-2 mRNA, was incorporated into liposomes to increase its intracellular delivery. This oligo selectively inhibited Bcl-2 protein expression and induced growth inhibition in t(14;18)-positive transformed follicular lymphoma (FL) cell lines. We studied the inhibitory effects of shorter liposomal P-ethoxy oligos (7, 9, 11 or 15 mer) in order to determine the activity of different oligo chain lengths targeted to the same Bcl-2 mRNA. At 12 μM, all the oligos inhibited the growth of a FL cell line. We compared the 7-mer oligo with the 20-mer oligo. The two oligos inhibited Bcl-2 protein expression similarly: 66% and 60% for the 7- and 20-mer, respectively. The uptake and retention of both oligos were also very similar. Our results indicate that the Bcl-2 inhibitory activity is maintained with P-ethoxy antisense oligos ranging from 7 to 20 bases. 相似文献
42.
43.
Jesús Porcayo Caldern Jos Luis Reyes Barragn Jesús Israel Barraza Fierro Hctor Cruz Mejía Cinthya Dinorah Arrieta Gonzlez Víctor Ravelero Vzquez Kevin Piedad Snchez María Teresa Torres-Mancera Rogel Fernando Retes-Mantilla Roberto Ademar Rodríguez-Díaz 《Materials》2022,15(12)
Aluminum-based alloys have been considered candidate materials for cathodic protection anodes. However, the Al-based alloys can form a layer of alumina, which is a drawback in a sacrificial anode. The anodes must exhibit uniform corrosion to achieve better performance. Aluminum can be alloyed with Zn to improve their performance. In this sense, in the present research, the electrochemical corrosion performance of Al-xZn alloys (x = 1.5, 3.5, and 5 at.% Zn) exposed to 3.5 wt.% NaCl for 24 h was evaluated. Polarization curves, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) were used to identify the electrochemical behavior. The microstructure of the samples before the corrosion assessment was characterized by means of X-ray diffraction analyses (XRD) and scanning electron microscopy (SEM). In addition, microstructures of the corroded surfaces were characterized using X-ray mappings via SEM. Polarization curves indicated that Zn additions changed the pseudo-passivation behavior from what pure Al exhibited in a uniform dissolution regime. Furthermore, the addition of Zn shifted the corrosion potential to the active side and increased the corrosion rate. This behavior was consistent with the proportional decrease in polarization resistance (Rp) and charge transfer resistance (Rct) in the EIS. The analysis of EIS was done using a mathematical model related to an adsorption electrochemical mechanism. The adsorption of chloride at the Al-Zn alloy surface formed aluminum chloride intermediates, which controlled the rate of the process. The rate constants of the reactions of a proposed chemical mechanism were evaluated. 相似文献
44.
目的 探讨自闭症谱系障碍(autism spectrum disorder,ASD)儿童与正常发育(typically developing,TD)儿童的脑功能网络拓扑结构差异。材料与方法 从国际自闭症脑成像交换数据库的4个站点中提取符合纳入标准的65例ASD儿童(ASD组)及65例TD儿童(TD组)的脑部静息态功能磁共振成像及T1加权结构像数据。应用图论分析研究大脑网络的拓扑结构,包括全局和局部拓扑参数。结果 在阈值范围内,ASD在聚类系数(clustering coefficient,Cp)和特征路径长度(characteristic path length,Lp)低于TD组(P<0.05);两组在全局效率(global efficiency,Eglob)、局部效率(local efficiency,Eloc)等指标的差异无统计学意义。ASD组和TD组的脑功能连接网络满足标准化的聚类系数(γ)>1和标准化的特征路径长度(λ)≈1,具有小世界网络属性,但两组间的γ和λ值差异无统计学意义。节点水平分析结果显示ASD组在双侧前扣带回、双侧尾状核、双侧海马、右侧顶下小叶等脑区的... 相似文献
45.
46.
Maria Carmen S.Tan Mary Stephanie S.Carranza Virgilio C.Linis Raymond S.Malabed Yves Ira A.Reyes Francisco C.FrancoJr Glenn G.Oyong 《Asian Pacific Journal of Tropical Biomedicine》2021,(10):460-468
Objective: To evaluate antioxidant, cytotoxic, and anti-venom capacity of crude bark extracts of Alstonia parvifolia Merr. Methods: Gas chromatography-mass spec... 相似文献
47.
María Verónica Reyes Francisco Vanaclocha Sebastián 《Seminarios de la Fundación Espa?ola de Reumatología》2012,13(3):77-84
Lupus erythematosus (LE) is an autoimmune inflammatory disease that includes a broad spectrum of manifestations, ranging from systemic disease (systemic lupus erythematosus [SLE]) to purely cutaneous forms (cutaneous lupus erythematosus [CLE]).Cutaneous involvement occurs in 90% of patients with SLE.Based on morphological and histopathological features, CLE can be divided into three categories: chronic CLE, subacute CLE and acute CLE.The precise etiology of LE is not fully understood, but the disease occurs when environmental factors, drugs and infectious agents trigger an abnormal immune response in an individual with predisposing genetic factors.To assess cutaneous involvement, several scores have been developed over the years. A recent study, called CLASI (Cutaneous Lupus Erythematosus Disease Area and Severity Index), staged mucocutaneous damage and disease activity separately, allowing assessment of therapeutic response to be standardized.The management of CLE is challenging. Although treatment traditionally consists of photoprotection, topical steroids and antimalarial agents, these measures are sometimes ineffective in subgroup of patients, giving rise to what is called resistant CLE.This article reviews the topical and systemic treatment options, both the classical and new treatment alternatives currently available. 相似文献
48.
William D. Lopez Louis F. Graham Caitlin Reardon Armando Matiz Reyes Angela Reyes Mark Padilla 《Journal of Men's Health》2012,9(4):255-260
BackgroundLatinos comprise 14% of the United States (U.S.) population, and approximately 75% of Latinos in the U.S. are immigrants or children of immigrants. Urban Latino men face a distinct set of structural barriers that may influence their health and well-being. The collapse of the automobile industry in Detroit, Michigan, contributed to increased rates of racially stratified unemployment.MethodThrough semi-structured interviews and ethnography, we present a case study of nine Latino men who face decreasing opportunities for formal employment and navigate the constant threat of violence and deportation in the face of Detroit's rapid deindustrialization.ResultsIn light of scarce work opportunities, participants sought income from the informal labor sector. This work was often illegal or dangerous, such as drug dealing, and perpetuated a cycle of violence. The threat of violence and deportation limited mobility and contact with authorities, especially among undocumented participants.ConclusionIn order to promote the health of urban Latino men, a careful consideration of the structural factors that shape their lives is essential. Interventions should work to leverage an extensive skill set and drive to work into meaningful formal employment, and consider the overarching effects of documentation on social mobility. 相似文献
49.
R. Reyes H. Merchant-Larios A. Ortega-Hernández N. M. Delgado 《Systems biology in reproductive medicine》2013,59(6):443-449
At present there is no accepted method for the regulation of male fertility. The most appropriate form of contraception would undoubtedly be to develop from traditional plant-derived folk drugs a contraceptive male method. Hypoosmotic shock is used for validate plasma membrane function and its fertilizing capacity of human sperm. Such effect is induced in human sperm in the presence of a purified fraction from Echeveria gibbiflora (PFEG) aqueous crude extract. The hypotonic-like effect included a distension of the plasma membrane over the acrosome region and in some occasions around the sperm middle piece. An enhanced activity of the immobilizing and agglutination effects was induced instantaneously after the addition of PEFG versus aqueous crude extract activity (OBACE). Using electron microscopy it was possible to observe a deposit of a ''sticky'' dense material intercalated along the plasma membrane. The membrane was sealed making it impossible to measure the viability or metabolic activity of the treated sperm by the fluorescence (FDA-IP) technique. It was also possible to corroborate the dispersion of the acrosomal content and the disappearance of the acrosomal and nuclear membrane. Results that makes PFEG hypotonic-like effect a serious candidate to conduct a study to determine the predicting capacity of this compound in human infertility and suggest that the plant may yield a compound suitable for use as male contraceptive agent. 相似文献
50.