全文获取类型
收费全文 | 582篇 |
免费 | 143篇 |
国内免费 | 16篇 |
专业分类
741篇 |
出版年
2024年 | 5篇 |
2023年 | 16篇 |
2022年 | 24篇 |
2021年 | 35篇 |
2020年 | 37篇 |
2019年 | 31篇 |
2018年 | 29篇 |
2017年 | 35篇 |
2016年 | 38篇 |
2015年 | 37篇 |
2014年 | 59篇 |
2013年 | 53篇 |
2012年 | 45篇 |
2011年 | 46篇 |
2010年 | 39篇 |
2009年 | 19篇 |
2008年 | 21篇 |
2007年 | 25篇 |
2006年 | 20篇 |
2005年 | 23篇 |
2004年 | 9篇 |
2003年 | 17篇 |
2002年 | 7篇 |
2001年 | 2篇 |
2000年 | 3篇 |
1999年 | 8篇 |
1998年 | 4篇 |
1997年 | 8篇 |
1996年 | 6篇 |
1995年 | 2篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 2篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1979年 | 3篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有741条查询结果,搜索用时 12 毫秒
721.
快速液体衰减反转回复序列在颅脑肿瘤诊断中的应用价值 总被引:6,自引:0,他引:6
126例颅脑肿瘤同时行快速液体反转回复序列成像和常规FSET2W成像。通过比较分析两者显示病变的能力,探讨FLIAR对颅脑肿瘤的诊断价值。结果显示示FLAIR序列MRI较T2WI有更高的对比度,在显示病变的部位,大小,轮廓,范围和数目方面具有更好的敏感性。 相似文献
722.
Detection of porin antigen in serum for early diagnosis of mouse infections with Salmonella typhimurium 总被引:3,自引:0,他引:3
Abstract The monoclonal antibodies to porin, an outer membrane protein isolated from Salmonella typhimurium and sandwich enzyme linked immunosorbent assay (ELISA) has made possible the detection of porin from sera of S. typhimurium -infected mice. The specificity of the monoclonal antibodies was ascertained based on their cross-reactivity with porins isolated from S. typhi, Shigella flexneri and Escherichia coli and lipopolysaccharide (LPS) of S. typhimurium and E. coli . Serum samples were found to be positive for porin as early as 3 days after intravenous and 5 days after oral infection. In addition, a positive correlation was observed between the bacterial load and the concentration of porin detected in the sera. On the other hand, analysis of sera for anti-porin antibody showed diametrically opposite time kinetics with antigenaemia. These results indicate that porin accumulates in the serum of infected mice much earlier than the appearance of antibodies to porin. Thus detection of porin holds promise for early diagnosis of typhoid. 相似文献
723.
724.
L. H. M. de Miranda L. P. Quintella I. B. dos Santos R. C. Menezes F. B. Figueiredo I. D. F. Gremião T. Okamoto R. V. C. de Oliveira S. A. Pereira R. Tortelly T. M. P. Schubach 《Mycopathologia》2009,168(2):79-87
The present study reports the histopathological findings of 86 skin lesions of dogs with sporotrichosis from Rio de Janeiro.
Suppurative granulomatous inflammation was the predominant finding and was observed in 76 (88.37%) cases. Plasma cells surrounding
the suppurative granulomas were detected in 68 (89.5%) cases and an inflammatory infiltrate at the periphery of these granulomatous
lesions was observed in 63 (82.9%). Fungus-specific staining revealed yeast cells compatible with Sporothrix schenckii in 36 cases. These fungal elements were only detected in lesions characterized by suppurative granulomatous inflammation.
Thus, specific staining of serial sections is recommended in the case of dogs with skin lesions whose histopathological presentation
is consistent with sporotrichosis. However, due to the generally small number of yeast cells in lesions, the hypothesis of
sporotrichosis should not be ruled out even if the result is negative, especially in epidemic areas where correlation with
epidemiological data is particularly useful. 相似文献
725.
Cell culture plays an important role in virology. It provides a platform for the detection and isolation of viruses as well as for the biochemistry and molecular biology based studies of viruses. In the present work, a new system that could permits multiple (different) cell lines to be simultaneously cultured in one dish was developed. In the system, each cell line was cultured in an isolated zone in the same dish or well and the system is therefore called an isolated co-culture system. The usefulness of this novel approach for virus isolation was demonstrated using a model system based on adenovirus. 相似文献
726.
Background Menkes disease is an X-linked recessive neurodevelopmental disorder resulting from mutation in a copper-transporting ATPase
gene. Menkes disease can be detected by relatively high concentrations of dopamine (DA) and its metabolites compared to norepinephrine
(NE) and its metabolites, presumably because dopamine-beta-hydroxylase (DBH) requires copper as a co-factor. The relative
diagnostic efficiencies of levels of catechol analytes, alone or in combination, in neonates at genetic risk of Menkes disease
have been unknown. Methods Plasma from 44 at-risk neonates less than 30 days old were assayed for DA, NE, and other catechols. Of the 44, 19 were diagnosed
subsequently with Menkes disease, and 25 were unaffected. Results Compared to unaffected at-risk infants, those with Menkes disease had high plasma DA (P < 10−6) and low NE (P < 10−6) levels. Considered alone, neither DA nor NE levels had perfect sensitivity, whereas the ratio of DA:NE was higher in all
affected than in all unaffected subjects (P = 2 × 10−8). Analogously, levels of the DA metabolite, dihydroxyphenylacetic acid (DOPAC), and the NE metabolite, dihydroxyphenylglycol
(DHPG), were imperfectly sensitive, whereas the DOPAC:DHPG ratio was higher in all affected than in all unaffected subjects
(P = 2 × 10−4). Plasma dihydroxyphenylalanine (DOPA) and the ratio of epinephrine (EPI):NE levels were higher in affected than in unaffected
neonates (P = 0.0015; P = 0.013). Conclusions Plasma DA:NE and DOPAC:DHPG ratios are remarkably sensitive and specific for diagnosing Menkes disease in at-risk newborns.
Affected newborns also have elevated DOPA and EPI:NE ratios, which decreased DBH activity alone cannot explain. 相似文献
727.
A promising serological field test for schistosomiasis could be developed by means of an immunohistoperoxidase procedure in the Defined Antigen Substrate Spheres (DASS) system. Sera of individuals with Schistosoma mansoni infections were examined with the DASS-system, using peroxidase labeled conjugates. The results were compared with those obtained with the Indirect Fluorescent Antibody (IFA) technique on frozen sections of the adult parasite. The DASS-system proved to give specific positive reactions at higher serum dilutions than the IFA-technique. The results of the test could readily be observed with the naked eye. 相似文献
728.
Feline immunodeficiency virus (FIV) is a common feline pathogen, with an overall infection prevalence of approximately 11% in cats worldwide. Most infected cats eventually succumb due to direct viral effects or, more commonly, to secondary infections resulting from virus-induced immunosuppression. FIV infection is considered lifelong, and diagnosis most often relies on detection of virus-specific antibodies. A currently available whole virus, adjuvanted, inactivated FIV vaccine induces antibodies in vaccinates that is indistinguishable from those induced by infection. As a result, currently available diagnostic tests cannot reliably distinguish vaccinated cats from infected cats, or from cats that are both vaccinated and infected. From both an epidemiologic and an individual cat perspective, it is impossible to determine whether use of this vaccination is more beneficial than it is harmful. 相似文献
729.
The prevalence of tinea capitis and the symptom-free colonisation of the scalp with dermatophytes were examined in 502 mentally
retarded participants who attended day care centers in the Tarsus district, Mersin, Turkey. Between December 2006 and May
2007, a screening study was conducted in three centers on a total of 316 (62.9%) male and 186 (37.1%) female participants
aged 12 ± 6.2 years. The examinations were carried out in parallel with the hairbrush, toothbrush, and cotton swab methods
by inoculation onto Sabouraud glucose agar. No participant was diagnosed with tinea capitis; however, we detected three carriers,
all of whom were boys aged 2–16 years. The total prevalence of carrier state was 0.6%. Of three boys, T. tonsurans was seen in two cases (66.7%), and in one case a zoophilic variant of T. mentagrophytes (33.3%) was isolated. The diagnosis was made via the hairbrush method in all three carriers. We also did a screening study
on ten households of the three asymptomatic carriers. T. mentagrophytes also was isolated in a 5-year-old sister of the boy with T. mentagrophytes colonisation. All the carriers were followed-up without any antimycotic treatment. In two of the participants, the carrier
state persisted at the 13th and 17th week follow-ups, and mycological clearance was documented at the 20th and 24th week for
these individuals. The third case and the household’s culture were found negative at the 7- and 12-week follow-ups. Despite
poor hygienic conditions and the participants’ difficulties in performing basic hygiene practices, asymptomatic carriage was
found to be surprisingly less prevalent among the mentally retarded individuals. 相似文献
730.
目的:观察乳腺良恶性病变的剪切波弹性成像(SWE)的典型表现,探讨SWE对乳腺良恶性病变的鉴别诊断价值。方法:选取2017年6月~2019年6月我院收治的162例行SWE检查的乳腺肿块患者,经组织活检或病理证实良性肿块105例(良性组)、恶性肿块57例(恶性组)。对比良、恶性组SWE的典型表现、SWE参数[最大值(Emax)、最小值(Emin)、平均值(Emean)、标准差(SD)、病灶与邻近脂肪弹性比值(SWE-Ratio)]的差异,分析SWE鉴别诊断乳腺良恶性病变的价值。结果:恶性组乳腺肿块"硬边征"检出率、Ⅲ型~Ⅴ型弹性图像检出率、Emax、Emean、SD、SWE-Ratio均高于良性组(P0.05),Emin低于良性组(P0.05)。Logistic多元回归分析结果显示,"硬边征"、Emax、Emean、SWE-Ratio与病理诊断乳腺肿块性质独立相关(P0.05)。受试者工作特征(ROC)曲线分析结果显示,"硬边征"、Emax、Emean、SWE-Ratio鉴别诊断乳腺良恶性病变的曲线下面积(AUC)分别为0.923、0.686、0.873、0.879。结论:SWE是诊断乳腺良恶性病变的有效影像手段,SWE的"硬边征"、SWE-Ratio、Emean对乳腺良恶性病变具有较高的鉴别价值。 相似文献