全文获取类型
收费全文 | 4530篇 |
免费 | 421篇 |
国内免费 | 1篇 |
出版年
2021年 | 68篇 |
2020年 | 33篇 |
2019年 | 48篇 |
2018年 | 50篇 |
2017年 | 43篇 |
2016年 | 88篇 |
2015年 | 179篇 |
2014年 | 187篇 |
2013年 | 233篇 |
2012年 | 298篇 |
2011年 | 318篇 |
2010年 | 220篇 |
2009年 | 182篇 |
2008年 | 239篇 |
2007年 | 237篇 |
2006年 | 213篇 |
2005年 | 199篇 |
2004年 | 190篇 |
2003年 | 198篇 |
2002年 | 211篇 |
2001年 | 128篇 |
2000年 | 113篇 |
1999年 | 80篇 |
1998年 | 57篇 |
1997年 | 34篇 |
1996年 | 37篇 |
1995年 | 32篇 |
1994年 | 27篇 |
1993年 | 44篇 |
1992年 | 69篇 |
1991年 | 50篇 |
1990年 | 47篇 |
1989年 | 65篇 |
1988年 | 59篇 |
1987年 | 50篇 |
1986年 | 43篇 |
1985年 | 38篇 |
1984年 | 37篇 |
1983年 | 29篇 |
1982年 | 23篇 |
1979年 | 33篇 |
1978年 | 32篇 |
1977年 | 29篇 |
1975年 | 32篇 |
1974年 | 33篇 |
1973年 | 38篇 |
1972年 | 28篇 |
1971年 | 22篇 |
1970年 | 21篇 |
1969年 | 25篇 |
排序方式: 共有4952条查询结果,搜索用时 0 毫秒
1.
2.
Pathogenic Neisseria use a variety of mechanisms to survive the bactericidal action of the complement system. Serum resistance is a crucial virulence factor for the development of severe meningococcal disease, meningococcal meningitis and disseminated gonococcal infection. Furthermore, local inflammation at the site of gonococcal infection exposes the bacteria to moderate concentrations of complement factors. We review current concepts of neisserial serum resistance with emphasis on porins and polysaccharides exposed on the neisserial surface and their interaction with components of normal human serum. 相似文献
3.
4.
5.
Summary The hybridization kinetics of DNA with labeled (18s+28s)rRNA from HeLa cells was determined in patients with trisomy 21, healthy probands with normal karyotype and in carriers of a t(DqGq) centric fusion. The results are in, accordance with the saturation values obtained earlier for these probands:Three patients with trisomy 21 showed an increased saturation level. In 2 of these patients the excess of rDNA exceeded the expected value considerably.Three of the investigated translocation carriers t(14q21q) showed significantly reduced saturation values, while results of a fourth proband with a dicentric chromosome t(15q21q) were found to be within the range of normal probands.The heterogeneous results were correlated with the cytogenetic characteristics of the acrocentric chromosomes. It is expected that these differences could be explained on the basis of family analysis.
Zusammenfassung Hybridisierungskinetiken der DNA mit markierter (18s+28s)rRNA aus HeLa-Zellen wurden ermittelt bei Patienten mit Trisomie 21, gesunden Probanden mit normalem Karyotyp und Trägern einer zentrischen Fusion t(DqGq). Die Ergebnisse bestätigen die bereits früher ermittelten Sättigungswerte von Hybridisierungen bei diesen Probanden:3 Patienten mit Trisomie 21 zeigten erhöhte Sättigungsniveaus. Bei 2 dieser Patienten übersteigt der Überschuß an rDNA den Erwartungswert erheblich.3 der untersuchten Translokationsträger t(14q21q) hatten signifikant erniedrigte Sättigungswerte, während die vierte Probandin mit dem dizentrischen Chromosom t(15q21q) im Normbereich lag.Die unterschiedlichen Befunde werden mit den cytogenetischen Eigenschaften der akrozentrischen Chromosomen in Zusammenhang gebracht. Es wird erwartet, daß diese Unterschiede sich durch Familienuntersuchungen aufklären lassen.相似文献
6.
7.
Nicolas Delaleu Heike Immervoll Janet Cornelius Roland Jonsson 《Arthritis research & therapy》2008,10(1):R22
Introduction
Sj?gren's syndrome (SS) is a systemic autoimmune disease that mainly targets the exocrine glands. The aim of this study was to investigate the involvement of 87 proteins measured in serum and 75 proteins analyzed in saliva in spontaneous experimental SS. In addition, we intended to compute a model of the immunological situation representing the overt disease stage of SS. 相似文献8.
A comparative study on steroid sulfatase and arylsulfatase C in fibroblast clones from 45,X/47,XXX and 69,XXY 总被引:2,自引:0,他引:2
Summary Steroid sulfatase (STS) and arylsulfatase C (ARSC) were studied in fibroblast clones from a 45,X/47,XXX mosaic and from a 69,XXY triploidy with one or two active X chromosomes. The comparison of the 47,XXX with 45,X clones showed an incomplete gene dosage effect (1.8 for STS and 2.0 for ARSC). This was not the case for the triploid clones with different X-inactivation patterns. These results confirm previous reports on the non-inactivation of the STS gene, and establish X linkage and non-inactivation for the ARSC gene as well. 相似文献
9.
10.
In 1983 a WHO collaborative study showed that the single radial immunodiffusion test provided a reliable system for the assay of the glycoprotein content of inactivated rabies vaccines. We have modified the method used in the collaborative study by using round plastic plates with wells arranged in a circle. Potency estimates were made by the multiple slope ratio method and not by single slope estimation procedures adjusted for a common intercept. We carried out a statistical evaluation of the accuracy and reliability of the precipitation area calculation. We confirmed that for the purpose of the potency estimation the area calculations were sufficiently precise in most instances. By analysing the sources of variation for round and for glass plates and by testing the variability of these methods we found that the round plates were as good as the glass plates. The advantage of the round plates was mainly in the ease of their handling: the agarose solution was poured in the plates without the need for a separate mould; an integral moist chamber with these plates was readily available; the precipitation zones were measured easily using a viewer which gave fourfold enlargements and the method required less antiglycoprotein. 相似文献