全文获取类型
收费全文 | 4395篇 |
免费 | 252篇 |
国内免费 | 11篇 |
专业分类
耳鼻咽喉 | 22篇 |
儿科学 | 89篇 |
妇产科学 | 52篇 |
基础医学 | 633篇 |
口腔科学 | 135篇 |
临床医学 | 407篇 |
内科学 | 1009篇 |
皮肤病学 | 41篇 |
神经病学 | 642篇 |
特种医学 | 151篇 |
外科学 | 545篇 |
综合类 | 87篇 |
一般理论 | 1篇 |
预防医学 | 221篇 |
眼科学 | 18篇 |
药学 | 256篇 |
中国医学 | 23篇 |
肿瘤学 | 326篇 |
出版年
2020年 | 33篇 |
2019年 | 37篇 |
2018年 | 45篇 |
2017年 | 36篇 |
2016年 | 54篇 |
2015年 | 67篇 |
2014年 | 62篇 |
2013年 | 123篇 |
2012年 | 131篇 |
2011年 | 175篇 |
2010年 | 102篇 |
2009年 | 119篇 |
2008年 | 163篇 |
2007年 | 165篇 |
2006年 | 149篇 |
2005年 | 180篇 |
2004年 | 186篇 |
2003年 | 179篇 |
2002年 | 162篇 |
2001年 | 165篇 |
2000年 | 156篇 |
1999年 | 161篇 |
1998年 | 78篇 |
1997年 | 58篇 |
1996年 | 75篇 |
1995年 | 51篇 |
1994年 | 36篇 |
1993年 | 47篇 |
1992年 | 93篇 |
1991年 | 117篇 |
1990年 | 109篇 |
1989年 | 91篇 |
1988年 | 97篇 |
1987年 | 106篇 |
1986年 | 89篇 |
1985年 | 85篇 |
1984年 | 74篇 |
1983年 | 66篇 |
1982年 | 51篇 |
1981年 | 34篇 |
1980年 | 33篇 |
1979年 | 59篇 |
1978年 | 55篇 |
1977年 | 46篇 |
1976年 | 43篇 |
1975年 | 46篇 |
1974年 | 57篇 |
1973年 | 42篇 |
1972年 | 46篇 |
1971年 | 52篇 |
排序方式: 共有4658条查询结果,搜索用时 15 毫秒
21.
Swartling J Pålsson S Platonov P Olsson SB Andersson-Engels S 《Medical & biological engineering & computing》2003,41(4):403-409
The optical properties of pig heart tissue were measured after in vivo ablation therapy had been performed during open-heart
surgery. In vitro samples of normal and ablated tissue were subjected to measurements with an optically integrating sphere
set-up in the region 470–900 nm. Three independent measurements were made: total transmittance, total reflectance and collimated
transmittance, which made it possible to extract the absorption and scattering coefficients and the scattering anisotropy
factor g, using an inverse Monte Carlo model. Between 470 and 700 nm, only the reduced scattering coefficient and absorption
could be evaluated. The absorption spectra were fitted to known tissue chromophore spectra, so that the concentrations of
haemoglobin and myoglobin could be estimated. The reduced scattering coefficient was compared with Mie computations to provide
Mie equivalent average radii. Most of the absorption was from myoglobin, whereas haemoglobin absorption was negligible. Metmyoglobin
was formed in the ablated tissue, which could yield a spectral signature to distinguish the ablated tissue with a simple optical
probe to monitor the ablation therapy. The reduced scattering coefficient increased by, on average, 50% in the ablated tissue,
which corresponded to a slight decrease in the Mie equivalent radius. 相似文献
22.
Radiation dose measurements with alanine/agarose gel and thin alanine films around a 192Ir brachytherapy source,using ESR spectroscopy 总被引:6,自引:0,他引:6
Olsson S Bergstrand ES Carlsson AK Hole EO Lund E 《Physics in medicine and biology》2002,47(8):1333-1356
Alanine/agarose gel and alanine films in stacks have been used for measurements of absorbed dose around an HDR 192Ir source in a vaginal cylinder-applicator, with and without a 180 degrees tungsten shield. The gel and the films were analysed by means of ESR spectroscopy and calibrated against an ion chamber in a 4 MV photon beam to obtain absolute dose values. The gel serves as both dosimeter and phantom material, and the thin (130 microm) films are used to achieve an improved spatial resolution in the dose estimations. Experimental values were compared with Monte Carlo simulations using two different codes. Results from the measurements generally agree with the simulations to within 5%, for both the alanine/agarose gel and the alanine films. 相似文献
23.
The effects of ageing and of chronic antidepressant treatment upon 5-HT transporter sites ([3H]paroxetine binding) in the rat hippocampus was examined. [3H]paroxetine binding to transporter sites was decreased with ageing in the hippocampus of control rats (38% decrease in dentate gyrus and CA4). Amitriptyline (10 mg/kg, i.p.) had no significant effect on [3H]paroxetine binding in 10 months old rats, but increased binding sites in 24 months rats in all hippocampal subregions (greatest increase of 109% in CA1 compared to saline controls). These data indicate an age-related decrease in hippocampal serotonin transporter sites and upregulation of these sites following 10 weeks of amitriptyline. The observed increase in transporter sites following amitriptyline may contribute to the general lower effectiveness of tricyclic antidepressants with ageing. 相似文献
24.
25.
26.
Cardiovascular purinoceptors 总被引:45,自引:0,他引:45
27.
Polyethylene tubings, 2-mm inner diameter and the length of 1 m, untreated or furnished with a covalently bonded heparin surface layer, were inserted as arteriovenous shunts bilaterally in dogs. By compressing the middle part, the initial blood flow was adjusted to 10 or 40 mL/min. The thrombogenicity of the tubings was assessed by the patency of the shunts and by assaying the generation of fibrinopeptide A (FPA) in arterial blood and in blood after its passage through the shunts. In untreated shunts clotting rapidly occurred preceded by high FPA generation in blood passing through the shunts. The blood flow in heparinized shunts remained unchanged throughout the test period. At the low flow rate a certain degree of FPA generation in the shunts occurred. At the high flow rate no changes in FPA levels occurred. The function of the heparin surface is thus flow rate dependent. Systematic heparinization and subsequent neutralization with protamine or administration of protamine alone did not interfere with the function of the heparin surface. 相似文献
28.
Kronqvist M Johansson E Whitley P Olsson S Gafvelin G Scheynius A van Hage-Hamsten M 《International archives of allergy and immunology》2001,126(1):41-49
BACKGROUND: The major allergen of the dust mite Lepidoglyphus destructor, Lep d 2, has been produced as a recombinant allergen (rLep d 2) with IgE reactivity both in vivo and in vitro. A modified form of rLep d 2 (rLep d 2.6Cys) obtained by site-directed mutagenesis has been shown to have a reduced IgE reactivity in vitro. In this study we have compared the ability of rLep d 2 and rLep d 2.6Cys to elicit positive skin prick tests and cellular responses among L. destructor-sensitized subjects. METHODS: Seventeen subjects were skin prick-tested with rLep d 2, rLep d 2.6Cys, histamine and negative controls and 17-20 h later skin biopsy specimens were taken from the skin prick-tested sites. The biopsy specimens were stained immunohistochemically for EG2+, CD3+, CD1a+, mast cell tryptase+, and IgE+ cells. Dermal cell infiltrates were judged in hematoxylin and eosin staining. Total IgE and allergen-specific IgE were determined by CAP-RAST. RESULTS: Compared to rLep d 2, rLep d 2.6Cys induced significantly smaller and fewer skin prick test reactions (p < 0.001) and dermal cell infiltrates (p < 0.05). Further, rLep d 2.6Cys induced fewer EG2+ cells (p < 0.001) but more tryptase+ cells (p < 0.05) than rLep d 2. A positive RAST to rLep d 2 was obtained for 88.2% of the subjects, while only 35.2% displayed a positive RAST to rLep d 2.6Cys. CONCLUSION: This study demonstrates that rLep d 2.6Cys is less able to evoke IgE-mediated reactions and cellular responses, as measured both in skin and in serum, than rLep d 2. In the future this hypoallergenic derivative may be a promising candidate molecule for immunotherapy of L. destructor-allergic patients. 相似文献
29.
A Kierkegaard L Norgren C G Olsson J Castenfors G Persson S Persson 《Acta medica Scandinavica》1987,222(5):409-414
In order to detect deep vein thrombosis (DVT), 101 patients with acute medical or infectious disorders were examined with the 125I-fibrinogen uptake test. All patients were bedridden on admission and were scanned daily from the second to the eighth day. Thirteen patients developed a positive fibrinogen uptake test. Thus, if a positive test is interpreted as DVT, the incidence of DVT was 13% in our bedridden patients. Of the patients admitted because of heart disease or pneumonia 20% had DVT, but only 4% of those admitted with other diagnoses. Other clinical "risk factors" studied, could not identify patients who developed DVT. 相似文献
30.
G Fredrikson S Nilsson H Olsson L Bj?rck B Akerstr?m P Belfrage 《Journal of immunological methods》1987,97(1):65-70
The newly described immunoglobulin G-binding streptococcal surface protein, protein G, was used to prepare and characterize rabbit antibodies. The antibodies were directed against rat hormone-sensitive lipase, the rate-limiting enzyme in the hydrolysis of the triacylglycerols stored in adipose tissue. Antiserum was obtained after two injections with 20 micrograms enzyme protein, and the immunoglobulin fraction was obtained using a protein G-based solid-phase radioimmunoassay. The hydrolysis of acylglycerols by the enzyme was inhibited by the antibodies, and the enzyme could be efficiently removed from a solution using the antibodies and heat-killed streptococci expressing surface protein G. By Western blot and detection with 125I-protein G, the antibodies were found to selectively bind to hormone-sensitive lipase and to a smaller extent to two minor contaminants, possibly proteolytic fragments of the lipase. The amount of 125I-labelled protein G bound to the lipase on the blot was quantitatively related to the amount of enzyme protein down to the detection limit 10 ng. 相似文献