全文获取类型
收费全文 | 11889篇 |
免费 | 968篇 |
国内免费 | 37篇 |
专业分类
耳鼻咽喉 | 191篇 |
儿科学 | 266篇 |
妇产科学 | 189篇 |
基础医学 | 1622篇 |
口腔科学 | 164篇 |
临床医学 | 1287篇 |
内科学 | 2460篇 |
皮肤病学 | 161篇 |
神经病学 | 1138篇 |
特种医学 | 418篇 |
外科学 | 1860篇 |
综合类 | 164篇 |
一般理论 | 27篇 |
预防医学 | 1037篇 |
眼科学 | 181篇 |
药学 | 823篇 |
3篇 | |
中国医学 | 7篇 |
肿瘤学 | 896篇 |
出版年
2024年 | 46篇 |
2023年 | 131篇 |
2022年 | 179篇 |
2021年 | 421篇 |
2020年 | 245篇 |
2019年 | 398篇 |
2018年 | 522篇 |
2017年 | 367篇 |
2016年 | 355篇 |
2015年 | 376篇 |
2014年 | 530篇 |
2013年 | 574篇 |
2012年 | 997篇 |
2011年 | 977篇 |
2010年 | 572篇 |
2009年 | 493篇 |
2008年 | 799篇 |
2007年 | 790篇 |
2006年 | 739篇 |
2005年 | 733篇 |
2004年 | 683篇 |
2003年 | 506篇 |
2002年 | 514篇 |
2001年 | 88篇 |
2000年 | 61篇 |
1999年 | 83篇 |
1998年 | 89篇 |
1997年 | 74篇 |
1996年 | 63篇 |
1995年 | 49篇 |
1994年 | 53篇 |
1993年 | 41篇 |
1992年 | 27篇 |
1991年 | 29篇 |
1990年 | 33篇 |
1989年 | 32篇 |
1988年 | 27篇 |
1987年 | 25篇 |
1986年 | 25篇 |
1985年 | 24篇 |
1984年 | 16篇 |
1983年 | 17篇 |
1982年 | 11篇 |
1981年 | 16篇 |
1980年 | 9篇 |
1976年 | 6篇 |
1972年 | 4篇 |
1970年 | 4篇 |
1969年 | 6篇 |
1966年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 28 毫秒
21.
Beth Broussard Jeremy B. Radkins Michael T. Compton 《Community mental health journal》2014,50(6):629-636
Schizophrenia presents particular challenges to health literacy, partly due to associated neurocognitive deficits. In order to develop engaging, recovery-oriented, visually based psychoeducational tools pertaining to psychotic disorders, thirty-nine individuals, consisting of mental health service users with serious mental illnesses, family members, and mental health professionals, participated in informal discussions. Using suggestions from these groups, the first two psychoeducational booklets of a planned series were developed in collaboration with a graphic designer and visual artist. Content of the booklets was developed addressing four components: knowledge, self-efficacy/self-management, incorporating a workbook format, and planning/contracting. In a follow-up discussion group, mental health service users provided positive feedback on the completed booklets. The finished booklets are practical, accessible, engaging, and low-literacy. These and other innovative approaches are needed to enhance mental health care, promote self-efficacy/empowerment, and encourage communication between service users, family members, and providers, especially in light of limited health literacy, illness-related neurocognitive impairments, and stigma. 相似文献
22.
23.
24.
25.
26.
Wendy R. Galpern Christopher S. Coffey Alberto Albanese Ken Cheung Cynthia L. Comella Dixie J. Ecklund Stanley Fahn Joseph Jankovic Karl Kieburtz Anthony E. Lang Michael P. McDermott Jeremy M. Shefner Jan K. Teller John L. P. Thompson Sharon D. Yeatts H. A. Jinnah 《Neurotherapeutics》2014,11(1):117-127
With advances in the understanding of the pathophysiology of dystonia, novel therapeutics are being developed. Such therapies will require clinical investigation ranging from exploratory studies to examine safety, tolerability, dosage selection, and preliminary efficacy to confirmatory studies to evaluate efficacy definitively. As dystonia is a rare and complex disorder with clinical and etiological heterogeneity, clinical trials will require careful consideration of the trial design, including enrollment criteria, concomitant medication use, and outcome measures. Given the complexities of designing and implementing efficient clinical trials, it is important for clinicians and statisticians to collaborate closely throughout the clinical development process and that each has a basic understanding of both the clinical and statistical issues that must be addressed. To facilitate designing appropriate clinical trials in this field, we review important general clinical trial and regulatory principles, and discuss the critical components of trials with an emphasis on considerations specific to dystonia. Additionally, we discuss designs used in early exploratory, late exploratory, and confirmatory phases, including adaptive designs. 相似文献
27.
28.
29.
30.
Joanna J. Kaylor Jeremy D. Cook Jacob Makshanoff Nicholas Bischoff Jennifer Yong Gabriel H. Travis 《Proceedings of the National Academy of Sciences of the United States of America》2014,111(20):7302-7307
Absorption of a photon by a rhodopsin or cone-opsin pigment isomerizes its 11-cis-retinaldehyde (11-cis-RAL) chromophore to all-trans-retinaldehyde (all-trans-RAL), which dissociates after a brief period of activation. Light sensitivity is restored to the resulting apo-opsin when it recombines with another 11-cis-RAL. Conversion of all-trans-RAL to 11-cis-RAL is carried out by an enzyme pathway called the visual cycle in cells of the retinal pigment epithelium. A second visual cycle is present in Müller cells of the retina. The retinol isomerase for this noncanonical pathway is dihydroceramide desaturase (DES1), which catalyzes equilibrium isomerization of retinol. Because 11-cis-retinol (11-cis-ROL) constitutes only a small fraction of total retinols in an equilibrium mixture, a subsequent step involving selective removal of 11-cis-ROL is required to drive synthesis of 11-cis-retinoids for production of visual chromophore. Selective esterification of 11-cis-ROL is one possibility. Crude homogenates of chicken retinas rapidly convert all-trans-ROL to 11-cis-retinyl esters (11-cis-REs) with minimal formation of other retinyl-ester isomers. This enzymatic activity implies the existence of an 11-cis-specific retinyl-ester synthase in Müller cells. Here, we evaluated multifunctional O-acyltransferase (MFAT) as a candidate for this 11-cis-RE-synthase. MFAT exhibited much higher catalytic efficiency as a synthase of 11-cis-REs versus other retinyl-ester isomers. Further, we show that MFAT is expressed in Müller cells. Finally, homogenates of cells coexpressing DES1 and MFAT catalyzed the conversion of all-trans-ROL to 11-cis-RP, similar to what we observed with chicken-retina homogenates. MFAT is therefore an excellent candidate for the retinyl-ester synthase that cooperates with DES1 to drive synthesis of 11-cis-retinoids by mass action.Light perception begins with the absorption of a photon by an opsin pigment in the membranous outer segment (OS) of a rod or cone photoreceptor cell. The light-absorbing chromophore in most vertebrate opsins is 11-cis-retinaldehyde (11-cis-RAL). Photon capture isomerizes the 11-cis-RAL to all-trans-retinaldehyde (all-trans-RAL), inducing conformational changes in the protein that lead to its active meta-II state. After a brief period of signaling through the transduction cascade, meta II decays to yield apo-opsin and free all-trans-RAL. Light sensitivity is restored to the apo-opsin when it combines with 11-cis-RAL to regenerate the pigment. Conversion of all-trans-RAL to 11-cis-RAL is carried out by a multistep enzyme pathway called the visual cycle, located in cells of the retinal pigment epithelium (RPE) (1, 2). The retinoid isomerase in this pathway is Rpe65, which converts an all-trans-retinyl ester (all-trans-RE), such as all-trans-retinyl palmitate (all-trans-RP), to 11-cis-retinol (11-cis-ROL) and a free fatty acid (3–5). Retinyl esters are synthesized in RPE cells by lecithin:retinol acyl transferase (LRAT), which transfers a fatty acid from phosphatidylcholine to retinol (6, 7). LRAT converts both all-trans-ROL and 11-cis-ROL to their cognate esters with similar catalytic efficiency (8).A second visual cycle is present in Müller cells of the retina, providing 11-cis-ROL to cones (9–11). Cones, but not rods, can use 11-cis-ROL as a chromophore precursor to regenerate bleached opsin pigments (10, 12, 13). The isomerase in the noncanonical pathway is dihydroceramide desaturase (DES1) (11). DES1 catalyzes rapid equilibrium isomerization of retinol (11). At equilibrium, 11-cis-ROL is much less abundant than all-trans-ROL, due to the 4.1 kcal/mole difference in free energy between these isomers (14). Accordingly, a secondary source of energy is required to drive the conversion of all-trans-ROL to 11-cis-ROL by DES1. Retinas from cone-dominant species contain 11-cis-retinyl esters (11-cis-REs), whereas retinyl esters are much less abundant in retinas from rod-dominant species (11, 13, 15). Homogenates from cone-dominant chicken and ground-squirrel retinas convert all-trans-ROL predominantly to 11-cis-REs in the presence of palmitoyl CoA (palm CoA) (13, 16, 17). These observations suggest that selective esterification of 11-cis-ROL may be the driving force for 11-cis-retinoid formation. In the current work, we sought to identify the protein responsible for the 11-cis-RE-synthase activity in Müller cells. We evaluated multifunctional O-acyltransferase (MFAT) as a candidate for this synthase. MFAT, also called acyl-CoA wax-alcohol acyltransferase-2 (AWAT2), catalyzes palm CoA-dependent synthesis of triglycerides, wax monoesters, and retinyl esters (18). It is present in the endoplasmic reticulum and predominantly expressed in skin (18). The retinol-isomer specificity of MFAT, and its expression in ocular tissues, has not been studied. 相似文献