全文获取类型
收费全文 | 4657篇 |
免费 | 363篇 |
国内免费 | 3篇 |
出版年
2023年 | 12篇 |
2022年 | 42篇 |
2021年 | 79篇 |
2020年 | 48篇 |
2019年 | 60篇 |
2018年 | 62篇 |
2017年 | 73篇 |
2016年 | 131篇 |
2015年 | 212篇 |
2014年 | 217篇 |
2013年 | 301篇 |
2012年 | 384篇 |
2011年 | 379篇 |
2010年 | 258篇 |
2009年 | 230篇 |
2008年 | 295篇 |
2007年 | 323篇 |
2006年 | 298篇 |
2005年 | 250篇 |
2004年 | 266篇 |
2003年 | 236篇 |
2002年 | 216篇 |
2001年 | 45篇 |
2000年 | 40篇 |
1999年 | 56篇 |
1998年 | 69篇 |
1997年 | 45篇 |
1996年 | 40篇 |
1995年 | 47篇 |
1994年 | 39篇 |
1993年 | 35篇 |
1992年 | 28篇 |
1991年 | 27篇 |
1990年 | 27篇 |
1989年 | 19篇 |
1988年 | 14篇 |
1987年 | 13篇 |
1986年 | 12篇 |
1985年 | 20篇 |
1984年 | 9篇 |
1983年 | 4篇 |
1982年 | 8篇 |
1981年 | 10篇 |
1980年 | 5篇 |
1979年 | 5篇 |
1978年 | 5篇 |
1974年 | 3篇 |
1972年 | 5篇 |
1971年 | 3篇 |
1966年 | 4篇 |
排序方式: 共有5023条查询结果,搜索用时 281 毫秒
991.
An Essential Role for CD44 Variant Isoforms in Epidermal Langerhans Cell and Blood Dendritic Cell Function 总被引:13,自引:0,他引:13
下载免费PDF全文
![点击此处可从《The Journal of cell biology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Johannes M. Weiss Jonathan Sleeman Andreas C. Renkl Henning Dittmar Christian C. Termeer Sabine Taxis Norma Howells Martin Hofmann Gabriele Khler Erwin Schpf Helmut Ponta Peter Herrlich Jan C. Simon 《The Journal of cell biology》1997,137(5):1137-1147
Upon antigen contact, epidermal Langerhans cells (LC) and dendritic cells (DC) leave peripheral organs and home to lymph nodes via the afferent lymphatic vessels and then assemble in the paracortical T cell zone and present antigen to T lymphocytes. Since splice variants of CD44 promote metastasis of certain tumors to lymph nodes, we explored the expression of CD44 proteins on migrating LC and DC. We show that upon antigen contact, LC and DC upregulate pan CD44 epitopes and epitopes encoded by variant exons v4, v5, v6, and v9. Antibodies against CD44 epitopes inhibit the emigration of LC from the epidermis, prevent binding of activated LC and DC to the T cell zones of lymph nodes, and severely inhibit their capacity to induce a delayed type hypersensitivity reaction to a skin hapten in vivo. Our results demonstrate that CD44 splice variant expression is obligatory for the migration and function of LC and DC. 相似文献
992.
Sabine Münch-Garthoff Jean-Marc Neuhaus Thomas Boller Birgit Kemmerling Karl-Heinz Kogel 《Planta》1997,201(2):235-244
993.
We isolated the gene encoding lysine-ketoglutarate reductase (LKR, EC 1.5.1.8) and saccharopine dehydrogenase (SDH, ED 1.5.1.9) from an Arabidopsis thaliana genomic DNA library based on the homology between the yeast biosynthetic genes encoding SDH (lysine-forming) or SDH (glutamate-forming) and Arabidopsis expressed sequence tags. A corresponding cDNA was isolated from total Arabidopsis RNA using RT-PCR and 5 and 3 Race. DNA sequencing revealed that the gene encodes a bifunctional protein with an amino domain homologous to SDH (lysine-forming), thus corresponding to LKR, and a carboxy domain homologous to SDH (glutamate-forming). Sequence comparison between the plant gene product and the yeast lysine-forming and glutamate-forming SDHs showed 25% and 37% sequence identity, respectively. No intracellular targeting sequence was found at the N-terminal or C-terminal of the protein. The gene is interrupted by 24 introns ranging in size from 68 to 352 bp and is present in Arabidopsis in a single copy. 5 sequence analysis revealed several conserved promoter sequence motifs, but did not reveal sequence homologies to either an Opaque 2 binding site or a Sph box. The 3-flanking region does not contain a polyadenylation signal resembling the consensus sequence AATAAA. The plant SDH was expressed in Escherichia coli and exhibited similar biochemical characteristics to those reported for the purified enzyme from maize. This is the first report of the molecular cloning of a plant LKR-SDH genomic and cDNA sequence. 相似文献
994.
995.
Haase Hannelore Bartel Sabine Karczewski Peter Morano Ingo Krause Ernst-Georg 《Molecular and cellular biochemistry》1996,163(1):99-106
In canine myocardium, the -subunit of the L-type Ca2+ channel is phosphorylated by cAMP dependent protein kinase in vitro as well as in vivo (Haase et al. FEBS Lett 335: 217–222, 1993). We have assessed the identity of the -subunit as well as its in vivo phosphorylation in representative experimental groups of catecholamine-challenged canine hearts. Adrenergic stimulation by high doses of both noradrenaline and isoprenaline induced rapid (within 20 sec) and nearly complete phosphorylation of the Ca2+ channel -subunit. Phosphorylation in vivo was about 4-fold higher as compared to untreated controls. When related to catecholamine-depleted (reserpine-treated) hearts noradrenaline and isoprenaline increased the in vivo phosphorylation of the -subunit even 8-fold. This phosphorylation correlated positively with tissue levels of cAMP, endogenous particulated cAMP-dependent protein kinase (PKA) and the rate of contractile force development dP/dtmax. The results imply the involvement of a PKA-mediated phosphorylation of the Ca2+ channel -subunit in the adrenergic stimulation of intact canine myocardium. 相似文献
996.
Bartel Sabine Karczewski Peter Krause Ernst-Georg 《Molecular and cellular biochemistry》1996,163(1):31-38
The postnatal alterations of the composition of a subunit isoforms (Gic, G i3 Go, and Gq of G proteins, the adenylyl cyclase activity as well as of cAMP-regulated phosphoproteins e.g. troponin and phospholamban were investigated in the ventricular tissue of 1, 7, 30 days old rats. Quantitative immunodetection revealed a 5.7-fold decrease in Gi3 at 30th postnatal day compared with the postnatal day 1 and up to 15-fold at 4 months. The amounts of Gq and G as well as the G subunits were found to be higher in the earlier life period compared to the adult. In contrast, the content of Gs was uneffected by the developmental state. Basal adenylyl cyclase activity (pmoles cAMP/min × mg protein) increased from 30.9 ± 5.0, 36.8 ± 5.0 to 63.9 ± 5.9 at 1st, 7th and 30th postnatal day, respectively. Isoprenaline (100 M) enhanced the activity of adenylyl cyclase from day 1, 7–30 from 46.2 ± 7.0, 79.1 ± 9.2 to 120.5 ± 7.2, respectively. The effects of forskolin and NaF on adenylyl cyclase activity was found to be not influenced within the first postnatal month. Furthermore, a developmentally controlled expression of cardiac troponin I was observed (6-fold from the first to the 28th postnatal day) whereas the level of phospholamban was found to be age-independent.In conclusion, there is an increase in the efficiency of the -adrenergic signal transfer mainly caused by a reduction of the inhibitiory G proteins and a dominance of the Gs-linked pathway in the postnatal rat heart. Furthermore the developmentally controlled expression of troponin I might be of functional importance in the cAMP-supported relaxation. Additionally, altered Gq, Go and G pattern of the developing rat ventricle may play a role in the observed change of -adrenerg-mediated heart contractility as well as in cardiac differentiation and growth processes. 相似文献
997.
998.
Christine Fischer Sabine Schweigert Cord Spreckelsen Friedrich Vogel 《Human genetics》1996,97(2):129-137
We present an overview of the variety of databases and programs that offer substantial aid to medical and molecular geneticists. Databases and expert systems for genetic diseases and birth defects, programs for segregation and linkage analysis, certain DNA and protein sequence databases, and information resources in general for molecular biology are addressed. These systems cannot be used effectively without the newly developed techniques of information exchange based on international computer networks. A short introduction is given to the Internet and to European institutions and organizations that offer help with the aquisition and use of bioinformatic resources. 相似文献
999.
Ingrid Handig Erna Dams Franco Taroni Sabine Van Laere Thierry de Barsy Patrick J. Willems 《Human genetics》1996,97(3):291-293
Deficiency of carnitine palmitoyltransferase type II (CPT II) is a clinically heterogeneous autosomal recessive disorder of lipid metabolism. The most common mutation in the CPT 11 gene is the S113L mutation, which substitutes leucine for serine at amino acid position 113. We studied an inbred family with three affected cousins with CPT II deficiency and found the S113L mutation to be present in a homozygous state in all three patients. Pedigree analysis traced the S 113L mutation back to one common ancestor. Although the patients in this family have an identical genotype at the CPT II locus, their clinical picture ranges from asymptomatic to lethal. 相似文献
1000.