全文获取类型
收费全文 | 10527篇 |
免费 | 479篇 |
国内免费 | 46篇 |
专业分类
耳鼻咽喉 | 214篇 |
儿科学 | 804篇 |
妇产科学 | 396篇 |
基础医学 | 1006篇 |
口腔科学 | 360篇 |
临床医学 | 991篇 |
内科学 | 2019篇 |
皮肤病学 | 512篇 |
神经病学 | 491篇 |
特种医学 | 258篇 |
外科学 | 1489篇 |
综合类 | 381篇 |
一般理论 | 6篇 |
预防医学 | 931篇 |
眼科学 | 174篇 |
药学 | 630篇 |
1篇 | |
中国医学 | 15篇 |
肿瘤学 | 374篇 |
出版年
2017年 | 87篇 |
2016年 | 63篇 |
2015年 | 92篇 |
2014年 | 104篇 |
2013年 | 189篇 |
2012年 | 206篇 |
2011年 | 247篇 |
2010年 | 172篇 |
2009年 | 214篇 |
2008年 | 176篇 |
2007年 | 174篇 |
2006年 | 212篇 |
2005年 | 160篇 |
2004年 | 123篇 |
2003年 | 94篇 |
2002年 | 106篇 |
2001年 | 110篇 |
2000年 | 82篇 |
1999年 | 131篇 |
1998年 | 182篇 |
1997年 | 212篇 |
1996年 | 236篇 |
1995年 | 177篇 |
1994年 | 171篇 |
1993年 | 178篇 |
1992年 | 163篇 |
1991年 | 175篇 |
1990年 | 163篇 |
1989年 | 166篇 |
1988年 | 135篇 |
1987年 | 139篇 |
1986年 | 125篇 |
1985年 | 102篇 |
1984年 | 98篇 |
1983年 | 81篇 |
1982年 | 79篇 |
1981年 | 85篇 |
1980年 | 54篇 |
1979年 | 79篇 |
1978年 | 50篇 |
1977年 | 65篇 |
1976年 | 52篇 |
1959年 | 344篇 |
1958年 | 759篇 |
1957年 | 870篇 |
1956年 | 771篇 |
1955年 | 804篇 |
1954年 | 780篇 |
1949年 | 182篇 |
1948年 | 125篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
B R Broxup V E Valli G L Losos D H Percy E Farber I McMillan 《Toxicologic pathology》1988,16(4):401-417
Classification of rat hepatocellular proliferative lesions can vary between pathologists as the many qualitative histologic criteria have not been satisfactorily evaluated and ranked for prognostic value. Computer-assisted morphometry offers an objective method to evaluate certain cellular features. The Solt-Farber resistant hepatocyte model was used in this study to produce populations of rats with a full range of hepatocellular proliferative lesions. Cellular features within the lesions were then measured morphometrically and the data were analyzed by animal age and by subjective lesion diagnosis. The nuclear/cytoplasmic ratio followed by the cell area and nuclear area were found to be the most important parameters for separating microscopic foci and islands of cellular alteration, an early hyperplastic lesion, from other hepatocellular proliferative lesions. The coefficient of variation, as a relative measure of heterogeneity, increased in a linear manner for cell, nuclear and nucleolar areas as the animals aged and was significantly higher for cell and nuclear area in hepatocellular carcinoma compared to other hepatocellular proliferative lesions. Hepatocyte nodules (representing primarily late hyperplastic lesions) and persistent hepatocyte nodules (lesions with similarities to hepatocellular adenoma) could not be satisfactorily separated within the limits of this study. As these borderline lesions show a continuum of cytologic change, other features, such as architectural change, are necessary to satisfactorily classify them on a subjective basis. An alternative approach is to use discriminant functions derived from morphometric studies. 相似文献
102.
M VAN GRIENSVEN E C BERGIJK J J BAELDE E DE HEER J A BRUIJN 《Clinical and experimental immunology》1997,107(2):254-260
In patients with systemic lupus erythematosus, the female-to-male ratio is as high as 10:1. Sex hormones are thought to play a role in this difference in susceptibility. In a previous study, we demonstrated a high susceptibility of female mice to the development of glomerulonephritis after induction of chronic graft-versus-host disease (GVHD), compared with male mice. In order to unravel further this gender-related difference (C57Bl/10*DBA/2)F1 hybrid mice were either castrated or ovariectomized and treated with 17β-ethinyloestradiol or testosterone-decanoate preceding the induction of chronic GVHD. Testosterone-decanoate reduced significantly the development of albuminuria in females. In contrast, proteinuria of 17β-ethinyloestradiol-treated female mice was in the same range as that of sham-operated mice. Autoantibody levels against glomerular basement membrane, renal tubular epithelium, dsDNA and ssDNA, as determined by ELISA, were higher in 17β-ethinyloestradiol-treated female mice than in all other groups. Immunofluorescence studies showed the presence of immunoglobulin and complement deposits in glomeruli of all animals, without significant differences between the experimental groups. Our findings confirm earlier observations, in that testosterone-decanoate is shown to be an inhibitory compound, whereas 17β-ethinyloestradiol has stimulating properties in autoimmunity. Moreover, our results show for the first time differential hormonal effects on autoantibody levels and proteinuria in experimental lupus nephritis. 相似文献
103.
SHAN SHAN GUO YI ZHONG WANG XIU KUN WANG YING JIE GAO YA HONG JIN DE FENG LI GUI DONG YUAN YI ZHANG GUI ZHEN ZONG YE ZHAO XIAO LAN CUI Institute of Chinese Meteria Medica China Academy of Chinese Medical Sciences Beijing P. R. China Aerospace Central Hospital Beijing P. R. China 《中华微生物学和免疫学杂志(英文版)》2006,4(4):272-277
To observe the effect of Gardenia extract ZG on the adsorption quantity of herpes simplex virus type 1 (HSV-1) so as to explore the mechanism of its antiviral activity, fluorescein isothiocyanate (FITC) was used as the fluorescent probe to label viruses and heparin sodium was used as control. Meanwhile , the effect of Gardenia extract ZG on the adsorption quantity on the surface of Hep-2 cells was determined by flow cytometry. It was demonstrated that adsorption of HSV-1 on the surface of Hep-2 cells exhibited the character of saturation and specificity and heparin sodium could prevent attachment of viruses on these cells. These results are in accord with those reported previously. It was also proved that the manner of drug-use prior to adsorption or simultaneous use of drug and adsorption was better than adsorption prior to drug-use, and the inhibition rates of the former and latter manner were 84. 76% and 82.92% respectively. Three manners of drug-use with Gardenia extract ZG were all effective to reduce the adsorption quantity of viruses, especially the manner of simultaneous use of drug and adsorption with an adsorption inhibition rate of 68.46% . From the above observation, it is apparent that the mechanism of anti-viral activity of Gardenia extract ZG may be via several steps involved in the HSV-1 adsorption. 相似文献
104.
JUAN C. DE LA TORRE MARGARET MALLORY MICHELLE BROT LISA GOLD GEORGE KOOB MICHAEL B. A. OLDSTONE ELIEZER MASLIAH 《Virology》1996,220(2):508
Neurons have a restricted expression of MHC heavy chain molecules which prevents presentation of antigens of infecting viruses. As a result, such infected cells escape immune surveillance and allow the establishment of noncytolytic persistent infection. Here we show that a chronic noncytolytic viral infection bothin vitroandin vivoselectively perturbed the expression of GAP-43, a protein that plays a central role in neuronal plasticity processes accompanying learning and memory. GAP-43 expression was greatly decreased in the hippocampus, an area of heightened viral replication, while synaptic density was preserved. Concurrently, the ability to learn tasks was significantly impaired in these persistently infected mice. Yet, infected neurons remained free from structural injury. 相似文献
105.
106.
Permeation of human ovarian tissue with cryoprotective agents in preparation for cryopreservation 总被引:18,自引:10,他引:18
Newton H; Fisher J; Arnold JR; Pegg DE; Faddy MJ; Gosden RG 《Human reproduction (Oxford, England)》1998,13(2):376-380
The recent improvements in the treatment of cancer by chemo- and
radiotherapy have led to a significant increase in the survival rates of
patients with malignant disease, but at the expense of distressing side
effects. One major problem, especially for younger patients, is that
aggressive therapy destroys a significant proportion of the follicular
population, which can result in either temporary or permanent infertility.
Freeze-banking pieces of ovarian cortex prior to treatment is one strategy
for preserving fecundity. When the patient is in remission, fertility
could, theoretically, be restored by autografting the thawed tissue at the
orthotopic site or by growing isolated follicles to maturity in vitro.
Recent studies have found good follicular survival in frozen-thawed human
ovarian tissue but to optimize the process an effective cryopreservation
method needs to be developed. An essential part of such a technique is to
permeate the tissue with a cryoprotectant to minimize ice formation and the
extent of this equilibration is an important determinant of post-thaw
cellular survival. In the current study, we have investigated the diffusion
of four cryoprotective agents into human tissue at both 4 degrees C and 37
degrees C. We have also studied the effect of adding different
concentrations of the non penetrating cryoprotective agent, sucrose, to the
freezing media using the release of lactate dehydrogenase as a measure of
its protective effect. At 4 degrees C propylene glycol and glycerol
penetrated the tissue significantly slower than either ethylene glycol or
dimethyl sulphoxide. At the higher temperature of 37 degrees C all four
cryoprotectants penetrated at a faster rate, however concern about enhanced
toxicity prevents the use of these conditions in practice. Thus, the
results suggest that the best method of preparing tissue for freezing is
exposure for 30 min to 1.5 M solutions of ethylene glycol or dimethyl
sulphoxide at 4 degrees C; this achieved a mean tissue concentration that
was almost 80% that of the bathing solution. We also report that the
addition of low concentrations of sucrose to the freezing medium does not
have a significant protective effect against freezing injury.
相似文献
107.
108.
109.
110.