全文获取类型
收费全文 | 1385篇 |
免费 | 67篇 |
国内免费 | 7篇 |
专业分类
耳鼻咽喉 | 24篇 |
儿科学 | 45篇 |
妇产科学 | 13篇 |
基础医学 | 139篇 |
口腔科学 | 41篇 |
临床医学 | 137篇 |
内科学 | 345篇 |
皮肤病学 | 21篇 |
神经病学 | 50篇 |
特种医学 | 244篇 |
外科学 | 117篇 |
综合类 | 19篇 |
一般理论 | 2篇 |
预防医学 | 72篇 |
眼科学 | 24篇 |
药学 | 78篇 |
中国医学 | 2篇 |
肿瘤学 | 86篇 |
出版年
2022年 | 5篇 |
2021年 | 22篇 |
2020年 | 7篇 |
2019年 | 28篇 |
2018年 | 32篇 |
2017年 | 19篇 |
2016年 | 18篇 |
2015年 | 24篇 |
2014年 | 35篇 |
2013年 | 46篇 |
2012年 | 55篇 |
2011年 | 48篇 |
2010年 | 48篇 |
2009年 | 49篇 |
2008年 | 42篇 |
2007年 | 51篇 |
2006年 | 35篇 |
2005年 | 32篇 |
2004年 | 49篇 |
2003年 | 26篇 |
2002年 | 27篇 |
2001年 | 14篇 |
2000年 | 26篇 |
1999年 | 24篇 |
1998年 | 53篇 |
1997年 | 63篇 |
1996年 | 56篇 |
1995年 | 52篇 |
1994年 | 48篇 |
1993年 | 33篇 |
1992年 | 22篇 |
1991年 | 17篇 |
1990年 | 21篇 |
1989年 | 24篇 |
1988年 | 40篇 |
1987年 | 20篇 |
1986年 | 47篇 |
1985年 | 35篇 |
1984年 | 18篇 |
1983年 | 27篇 |
1982年 | 22篇 |
1981年 | 13篇 |
1980年 | 10篇 |
1979年 | 6篇 |
1978年 | 8篇 |
1977年 | 12篇 |
1976年 | 16篇 |
1975年 | 11篇 |
1969年 | 3篇 |
1968年 | 4篇 |
排序方式: 共有1459条查询结果,搜索用时 15 毫秒
1.
G Steinitz M C Martín N Gazit-Yaari M L Quesada J de la Nuez R Casillas U Malik Z B Begin 《Applied radiation and isotopes》2006,64(4):520-524
Multi-day signals, generally with duration of 2-10 days, are a prominent temporal variation type of radon (Rn) in geogas in the unsaturated zone. Rare multi-day Rn signals have been found which are characterized by: (a) a declining limb lasting up to 10 days which conforms to the radioactive decay of Rn, (b) recurs at the same location and (c) is recorded in diverse situations-volcanic and seismogenic. It suggested that a Rn blob is injected at a lower level on a steady upward flow of geogas whereby the rise and final fall of the signal are attributed to the edges of the blob while the central Rn-decay segment records the passing of the decaying blob itself. Rn-decay signals are a small subset of multi-day Rn signals which are considered as highly irregular and unusable for the understanding of geophysical processes. In difference, it is concluded that multi-day Rn signals are probably proxies of subtle geodynamic processes at upper crustal levels and are therefore significant for studying such processes. 相似文献
2.
3.
Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography 总被引:2,自引:0,他引:2
The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study. 相似文献
4.
5.
J. Belchi-Hernandez S. Moreno-Grau F. Sánchez-Gascón J. Bayo B. Elvira Rendueles B. Bartolomé J. M. Moreno J. Martinez Quesada R. Palacios Peláez 《Allergy》1998,53(3):241-248
Zygophyllum fahago is a herbaceous plant found widely in the Mediterranean area. There are no previous reports of its allergenicity. An aerobiologic and clinical survey was conducted in Murcia, southern Spain, to determine the quantity of airborne pollen and establish the possible role of this pollen as a cause of allergic symptoms. With a Hirst volumetric trap, we determined the atmospheric concentrations of this pollen in 1993, 1994,1995, and 1996. Of 1180 patients tested, 181 (15,34%) had a positive skin test. To determine its allergenicity, we divided 47 patients into three groups: in group 1, all the patients had symptoms of rhinoconjunctivitis plus asthma; in groups 2 and 3, rhinoconjunctivitis. In group 1, we performed a bronchial provocation test (BPT): in groups 2 and 3, we performed nasal provocation (NPT) and conjunctival provocation (CPT) tests, respectively, SDS-PAGE was used to characterize the antigenic fractions and RAST inhibition to determine cross-reactivity with other pollens. The pollen dispersion period is from May to September (445 grains/m3 ), BPT was positive in 13 of 15 patients, NPT in 14 of 16 patients, and CPT in 13 of 16 patients. RAST inhibition revealed cross-reactivity with Mercurialis, Ricinus, Olea. and Betula. SDS-PAGE identified 25 IgE antibody-binding components, five of which (60, 65, 41, 38, and 15.5/14,7 kDa) were recognized by 40% of the sera. By SDS-PAGE immunoblotting with sunflower antiprofilin rabbit serum and affinity chromatography we established that the Z. fahago extract has profilin. This study shows that this pollen becomes airborne and elicits an IgE response which triggers respiratory symptoms in allergic subjects. 相似文献
6.
7.
8.
The literature on this rare tumour has been reviewed and three cases of nasal plasmacytoma are described. Immunohistochemistry demonstrated cytoplasmic IgA and Kappa determinants in all cases. Two patients are disease-free at the present time, the third developed an IgG-k multiple myeloma, previously not described in the literature. 相似文献
9.
J R Quesada 《Immunobiology》1986,172(3-5):250-254
10.
Ralls PW; Johnson MB; Kanel G; Dobalian DM; Colletti PM; Boswell WD Jr; Radin DR; Halls JM 《Radiology》1986,161(2):451-454
FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease. 相似文献