全文获取类型
收费全文 | 973篇 |
免费 | 79篇 |
国内免费 | 3篇 |
专业分类
耳鼻咽喉 | 5篇 |
儿科学 | 15篇 |
妇产科学 | 10篇 |
基础医学 | 133篇 |
口腔科学 | 53篇 |
临床医学 | 88篇 |
内科学 | 211篇 |
皮肤病学 | 6篇 |
神经病学 | 72篇 |
特种医学 | 16篇 |
外科学 | 74篇 |
综合类 | 10篇 |
预防医学 | 170篇 |
眼科学 | 33篇 |
药学 | 113篇 |
中国医学 | 2篇 |
肿瘤学 | 44篇 |
出版年
2023年 | 13篇 |
2022年 | 21篇 |
2021年 | 31篇 |
2020年 | 34篇 |
2019年 | 18篇 |
2018年 | 38篇 |
2017年 | 23篇 |
2016年 | 23篇 |
2015年 | 32篇 |
2014年 | 34篇 |
2013年 | 61篇 |
2012年 | 89篇 |
2011年 | 104篇 |
2010年 | 54篇 |
2009年 | 56篇 |
2008年 | 56篇 |
2007年 | 67篇 |
2006年 | 55篇 |
2005年 | 26篇 |
2004年 | 26篇 |
2003年 | 27篇 |
2002年 | 38篇 |
2001年 | 6篇 |
2000年 | 5篇 |
1999年 | 6篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 2篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 6篇 |
1988年 | 5篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 11篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 3篇 |
1966年 | 5篇 |
排序方式: 共有1055条查询结果,搜索用时 15 毫秒
1.
2.
3.
In this issue of Immunity, Anderson et al. provide another clue to the riddle that is Aire--why do human beings and mice lacking Aire develop diffuse and pathogenic autoimmunity? They find that Aire influences central tolerance not only by promoting the expression of peripheral self-proteins in thymic medullary epithelial cells (MECs) but also by furnishing these cells with the apparatus for effective antigen presentation (). 相似文献
4.
Mallikarjuna Rao GN Hussain T Geetha Devi N Jain S Chandak GR Ananda Raj MP 《Indian journal of medical sciences》2003,57(1):1-6
66 unrelated patients from Southern India with Duchenne Muscular Dystrophy (DMD) were studied for intragenic deletion in 18 exons and Pm region of the DMD gene using multiplex PCR. Of these 41 (62.1%) showed intragenic deletions. 78% of the deletions were located at the distal hotspot region (44-55 exons) and 22% of the deletions were located at the proximal region (exon 2-19). Exon 50 is most frequently deleted. Deletions in isolated cases were significantly more compared to familial cases. The lower incidence reported from South India compared to North India, is suggestive of variations in the Southern and Northern population. 相似文献
5.
Peter Molenaar Grant A. McPherson Errol Malta Colin Raper 《Naunyn-Schmiedeberg's archives of pharmacology》1985,331(2-3):240-246
Summary The affinity and efficacy of a number of sympathomimetic amines structurally related to prenalterol and the selective 1-adrenoceptor agonist RO 363 were determined using a combination of radioligand binding and organ bath techniques. Affinity of the molecules (pK
D) was calculated from their ability to displace the radioligand [125I]iodocyanopindolol ([125I]CYP) from -adrenoceptor sites in left atrial (1) and uterine (2) membrane homogenates. These pK
D values were used to calculate efficacy from the positive inotropic and uterine relaxant responses elicited by the drugs in organ bath experiments. The drugs studied were either arylethanolamines i.e., (–)-isoprenaline (ISO), p-hydroxyisoprenaline (pOH-ISO), compounds XIV and XVI or aryloxypropanolamine-derivatives, i.e., oxymethylene-isoprenaline (OM-ISO), prenalterol and Compound XI which possessed ap-phenol or catechol ring and an isopropyl or a homoveratryl amine substituent. Only ISO, OM-ISO, pOH-ISO and Compound XVI were active as agonists in both tissue preparations. These drugs were partial agonists which exhibited a wide range of pD2 values and did not display any marked selectivity for either -adrenoceptor subtype. Compound XI and prenalterol were inactive as agonists and together with the partial agonists behaved as competitive antagonists to ISO in the two preparations. All drugs tested displaced [125I]CYP from -adrenoceptor sites, however, there was also a wide range of potency amongst the drugs.Analysis of the structure-affinity and structure-efficacy relationships indicated that removal of the 3-hydroxyl group from the catechol ring reduces both affinity and efficacy without altering the selectivity of the drug for either -adrenoceptor subtype. While aryloxypropanolamine derivatives have generally higher affinities than arylethanol-amines, especially at -adrenoceptor sites, their efficacies are generally reduced at both -adrenoceptors. The presence of a homoveratryl group in aryloxypropanolamines enhances slightly the affinity for 1- and reduces affinity for 2-adrenoceptors. With this amine group, efficacy is markedly reduced at 2- as opposed to 2-adrenoceptor sites.Thus for prenalterol, the small degree of cardioselectivity can be attributed to the oxymethylene group whilst its lack of agonist activity (i.e., efficacy) reflects a combined action of this group and the absence of the 3-hydroxyl group on the phenyl ring. In RO363 it can be deduced that the oxymethylene group, together with the homoveratryl substituent are responsible for the observed selective affinity of the drug for 1- as opposed to 2-adrenoceptors. 相似文献
6.
Summary The rate of unstimulated influx of Ca2+ into rat aorta smooth muscle, measured as uptake of 45Ca, was inhibited in the presence of endothelium as compared to influx in the absence of endothelium. Efflux of 45Ca from unstimulated prelabelled tissues was also reduced in the presence of endothelium. In normal physiological solution the rate of influx and efflux of Ca2+ stimulated by B-HT 920 (1 and 10 M), but not that stimulated by phenylephrine (30 nM and 1 M), was also reduced in the presence of endothelium. In the presence of the calcium entry blocker flunarizine (3 M), phenylephrine (1 M) stimulated efflux of Ca2+ was inhibited by the presence of endothelium. A correlation between inhibition of Ca2+ influx and modulation of -adrenoceptor agonist-induced contractions by endothelium could not be demonstrated, and methylene blue, an antagonist of endothelium mediated inhibition of B-HT 920 contractions, did not affect Ca2+ influx stimulated by the agonist. The effects of endothelium on Ca2+ influx and efflux are unlikely to be due to alterations by endothelium of diffusion of 45Ca or the agonists in the vessel. The results demonstrate that an endothelial derived factor or factors can reduce calcium influx into smooth muscle cells and also modulate the release of calcium from cells, perhaps by affecting intracellular calcium pumping mechanisms. A reduction of calcium influx cannot be the sole explanation for the modulatory effect of endothelium on -adrenoceptor agonist-induced contractions but an effect on intracellular calcium metabolism may be important. 相似文献
7.
Irina Maljkovic Berry Melanie C. Melendrez Simon Pollett Katherine Figueroa Darunee Buddhari Chonticha Klungthong Ananda Nisalak Michael Panciera Butsaya Thaisomboonsuk Tao Li Tyghe G. Vallard Louis Macareo In-Kyu Yoon Stephen J. Thomas Timothy Endy Richard G. Jarman 《Emerging infectious diseases》2021,27(6):1637
Dengue control approaches are best informed by granular spatial epidemiology of these viruses, yet reconstruction of inter- and intra-household transmissions is limited when analyzing case count, serologic, or genomic consensus sequence data. To determine viral spread on a finer spatial scale, we extended phylogenomic discrete trait analyses to reconstructions of house-to-house transmissions within a prospective cluster study in Kamphaeng Phet, Thailand. For additional resolution and transmission confirmation, we mapped dengue intra-host single nucleotide variants on the taxa of these time-scaled phylogenies. This approach confirmed 19 household transmissions and revealed that dengue disperses an average of 70 m per day between households in these communities. We describe an evolutionary biology framework for the resolution of dengue transmissions that cannot be differentiated based on epidemiologic and consensus genome data alone. This framework can be used as a public health tool to inform control approaches and enable precise tracing of dengue transmissions. 相似文献
8.
Beatriz Togoro Ferreira da Silva Livia Tosi Trevelin Ananda Carolina Schroeter Amanda Endres Willers Paulo Francisco Cesar Adriana Bona Matos 《European journal of oral sciences》2021,129(1):e12754
This study investigated the effect of irradiation with an erbium‐doped yttrium aluminium garnet (Er:YAG) laser and coating with silica on the surface characteristics, bond strength, and flexural strength of dental zirconia. Three hundred and forty‐three standard zirconia specimens were created, and 49 were assigned to each of seven surface treatment groups: (i) no treatment; Er:YAG laser (80 mJ/2 Hz) with pulse widths of 50 μs (ii), 100 μs (iii), 300 μs (iv), or 600 μs (v); or tribochemical silica coating at the partially sintered stage (vi) or after sintering was complete (vii). All specimens were sintered after the surface treatments, except for the group in which specimens were sintered before treatment. The study outcomes were roughness, surface loss, microshear bond strength (μSBS), and biaxial flexural strength (BFS). Mean roughness and surface loss values were significantly higher in specimens from irradiated groups than in those from silica‐coated groups. Regarding μSBS, after aging, specimens from all experimental groups presented very low and similar μSBS values, irrespective of the surface treatment. Silica coating after sintering yielded the highest BFS (1149.5 ± 167.6 MPa), while coating partially sintered specimens with silica resulted a BFS (826.9 ± 60.9 MPa) similar to that of the untreated control group (794.9 ± 101.7 MPa). Laser treatments, irrespective of pulse width used, significantly decreased the BFS. In the group treated with laser at 300 μs pulse width, specimens exhibited the lowest BFS value (514.1 ± 71.5 MPa). Adhesion to zirconia was not stable after aging, regardless of the surface treatment implemented. 相似文献
9.
10.
Alice Song Edson Abdala Daniel Waisberg Rodrigo Bronze Martino Ho Yeh Li Luiz Marcelo Sa Malbouisson Ryan Yukimatsu Tanigawa Amaro Duarte Neto Guilherme Marques Andrade Liliana Ducatti Andre Mario Doi João Renato Rebello Pinho Michele Gomes‐Gouvea Fernanda Malta Lecio Figueira Pinto Bruno Fukelmann Guedes Luciana Haddad Venancio Avancini F. Alves Luiz Augusto D. Albuquerque 《The Brazilian journal of infectious diseases》2018