全文获取类型
收费全文 | 672篇 |
免费 | 39篇 |
国内免费 | 31篇 |
专业分类
儿科学 | 36篇 |
妇产科学 | 9篇 |
基础医学 | 201篇 |
口腔科学 | 15篇 |
临床医学 | 77篇 |
内科学 | 143篇 |
皮肤病学 | 6篇 |
神经病学 | 30篇 |
特种医学 | 59篇 |
外科学 | 37篇 |
综合类 | 21篇 |
预防医学 | 25篇 |
眼科学 | 8篇 |
药学 | 56篇 |
中国医学 | 1篇 |
肿瘤学 | 18篇 |
出版年
2022年 | 8篇 |
2021年 | 6篇 |
2018年 | 10篇 |
2017年 | 6篇 |
2015年 | 7篇 |
2014年 | 13篇 |
2013年 | 17篇 |
2012年 | 16篇 |
2011年 | 16篇 |
2010年 | 18篇 |
2009年 | 25篇 |
2008年 | 23篇 |
2007年 | 32篇 |
2006年 | 19篇 |
2005年 | 18篇 |
2004年 | 16篇 |
2003年 | 16篇 |
2002年 | 14篇 |
2001年 | 23篇 |
2000年 | 15篇 |
1999年 | 20篇 |
1998年 | 16篇 |
1997年 | 20篇 |
1996年 | 19篇 |
1995年 | 15篇 |
1994年 | 22篇 |
1993年 | 19篇 |
1992年 | 18篇 |
1991年 | 20篇 |
1990年 | 12篇 |
1989年 | 18篇 |
1988年 | 15篇 |
1987年 | 16篇 |
1986年 | 8篇 |
1985年 | 15篇 |
1984年 | 13篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 18篇 |
1980年 | 9篇 |
1979年 | 13篇 |
1978年 | 11篇 |
1977年 | 10篇 |
1976年 | 6篇 |
1975年 | 9篇 |
1974年 | 6篇 |
1972年 | 12篇 |
1971年 | 6篇 |
1969年 | 6篇 |
1968年 | 5篇 |
排序方式: 共有742条查询结果,搜索用时 15 毫秒
1.
Montalescot et al.1 recently demonstrated that patients withSTEMI and NSTEMI have similar in-hospital and long-term prognosesas well as similar independent correlates of outcome, despite 相似文献
2.
3.
4.
Neuroimaging in Pineal Tumors 总被引:4,自引:0,他引:4
F Reis MD AV Faria MD PhD VA Zanardi MD PhD JR Menezes MD F Cendes MD PhD LS Queiroz MD PhD 《Journal of neuroimaging》2006,16(1):52-58
BACKGROUND AND PURPOSE: The authors report radiological findings in 11 tumors in the pineal region, which were histologically diagnosed as germinomas, pineocytomas pineoblastomas, ependymomas, teratomas, and astrocytomas. METHODS: Computed tomography (CT) was performed in seven patients and magnetic resonance imaging (MRI) was performed in all patients. RESULTS: CT showed a solid or solid/cystic mass with variable contrast enhancement. MRI showed a heterogeneous mass, with hypointense signal on T1 and iso/hyperintense signal on T2-weighted images (WI) and gadolinium enhancement. Extension to adjacent structures occurred in five patients and spread through the cerebral spinal fluid (CSF) in two. CONCLUSIONS: Pineal region tumors have no pathognomonic imaging pattern. MRI and CT are complementary in diagnosis and are important to determine localization, extension, and meningeal spread. 相似文献
5.
6.
7.
Activation of influenza A viruses by trypsin treatment. 总被引:86,自引:0,他引:86
A comparative analysis has been carried out on the infectivity of virus of several influenza A strains grown in different host systems. Strains A/swine/Shope/31 (Hsw1N1), A/PR/8/34 (HON1), A/FM/1 (H1N1), A/Singapore/1/57 (H2N2), A/equine/Miami/1/63 (Heq2Neq2), and A/chick/Germany/49 (Hav2Neq1) exhibit host-dependent differences in infectivity. Virions grown in embryonated eggs and cultures of chorioallantoic membrane cells are highly infectious, whereas virions grown in cultures of chick embryo cells have a low infectivity that significantly increases after treatment in vitro with trypsin. In contrast, fowl plague viruses do not show host-dependent variations in infectivity. Virions grown in all host systems tested are highly infectious, and the infectivity of virions grown in chick embryo cells cannot be enhanced by trypsin treatment.The activation of virus particles appears to be based on the cleavage of hemagglutinin glycoprotein HA. This concept is supported by the following observations: (i) In virions of low infectivity only uncleaved glycoprotein HA can be detected. Virions of high infectivity exhibit complete or at least partial cleavage of the hemagglutinin. (ii) The activation of virions by trypsin treatment is always paralleled by cleavage of HA. (iii) Cleavage of HA is the only effect which can be detected after trypsin treatment. The neuraminidase is neither inactivated nor removed from the virion. (iv) Studies on recombinants of virus N and fowl plague virus (Rostock) show that host-dependent variation of infectivity and activation by trypsin, features specific for parent virus N, are found only with recombinant N(H)-FPV/Ro(N) but not with recombinant FPV/Ro(H)-N(N).Efficient plaque formation and serial passages are possible only if highly infectious particles are formed in a given host system. Thus, all strains analyzed undergo, in the absence of trypsin, successive growth cycles in eggs and chorioallantoic membrane cells and form plaques in chorioallantoic membrane cells. In contrast, in chick embryo cells only viruses containing the fowl plague virus hemagglutinin produce plaques and replicate under multiple cycle conditions without the addition of trypsin.The data show that cleavage of HA is not a precondition for virus assembly and hemagglutinating activity, but that it is necessary for infectivity. These findings are compatible with the hypothesis that, in addition to its role in adsorption, the hemagglutinin has another function in the infection process and cleavage is required for this function. 相似文献
8.
Biological functions of monospecific antibodies to envelope glycoproteins of Newcastle disease virus 总被引:2,自引:0,他引:2
Umino Y. Kohama T. Kohase M. Sugiura A. Klenk H. -D. Rott R. 《Archives of virology》1984,81(1-2):53-65
Summary Monospecific antisera to HN and F glycoproteins of Newcastle disease virus were prepared, and their effects on the biological activities of the virus were investigated. Anti-HN serum inhibited hemagglutinating and neuraminidase activity, as well as hemolysis. Anti-F serum had no effect on hemagglutination or neuraminidase but inhibited hemolysis and virus-induced cell fusion.Anti-HN serum was highly neutralizing, while neutralization by anti-F serum was very inefficient in conventional plaque reduction tests, although both sera were estimated to contain comparable amounts of antibody reacting with the virus as indicated by complement fixation and immunodiffusion tests. The neutralizing activity of anti-F serum was greatly enhanced by the addition of anti-IgG serum or fresh guinea pig serum, whereas that of anti-HN serum was little enhanced.Anti-HN serum incorporated in the agar overlay suppressed the development of plaques to some degree, while anti-F serum had little effect. The combination of anti-HN and anti-F sera resulted in a marked decrease in the number and size of plaques, demonstrating the synergistic effect of the two species of antibody in the containment of the spread of viral infection.With 8 Figures 相似文献
9.
Volcik KA Blanton SH Tyerman GH Jong ST Rott EJ Page TZ Romaine NK Northrup H 《American journal of medical genetics》2000,95(1):21-27
The C677T and A1298C mutations in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene are each associated with reduced MTHFR activity. The C677T mutation in the heterozygous and homozygous state correlates with increased enzyme thermolability, with homozygous mutant genotypes showing significantly elevated plasma homocysteine levels and decreased plasma folate levels. The A1298C mutation results in decreased MTHFR activity, but changes in neither homocysteine nor folate levels are associated with A1298C variant genotypes. Our study determined the frequencies of the C677T and A1298C MTHFR mutations for spina bifida (SB) cases, mothers and fathers of SB cases, and controls in Hispanics of Mexican-American descent. In addition, our subject population was further categorized as to whether the spina bifida lesion occurred as an upper or lower level defect, according to the Van Allen "multi-site closure" model. Hispanic SB cases with upper level defects and their mothers were homozygous for the C677T variant allele at a higher rate than their respective controls (OR = 1.5 [95% CI 0.8-2.9], P = 0.30; OR = 2.3 [1.1-4.8], P = 0.04, respectively), with statistically significant results seen only for the maternal homozygous genotype. Homozygosity for the A1298C mutation was seen at a higher rate only in Hispanic mothers of both upper and lower level SB cases when compared to controls, but these results were not statistically significant. Our study provides evidence that the maternal C677T MTHFR homozygous mutant genotype is a risk factor for upper level spina bifida defects in Hispanics. 相似文献
10.
H.-D. Rott 《Clinical genetics》1984,26(1):36-38
Dermatoglyphic investigation of palm prints in patients with Incontinentia pigmenti revealed in five of eight cases a partial ridge dissociation with lack of sweat gland pores. This disease can, therefore, be accepted as a second X-linked anhidrotic ectodermal dysplasia, which, however, is only segregated in the female. 相似文献