全文获取类型
收费全文 | 712篇 |
免费 | 55篇 |
专业分类
767篇 |
出版年
2023年 | 3篇 |
2021年 | 5篇 |
2020年 | 2篇 |
2018年 | 3篇 |
2017年 | 5篇 |
2016年 | 15篇 |
2015年 | 24篇 |
2014年 | 26篇 |
2013年 | 32篇 |
2012年 | 44篇 |
2011年 | 46篇 |
2010年 | 32篇 |
2009年 | 33篇 |
2008年 | 50篇 |
2007年 | 43篇 |
2006年 | 51篇 |
2005年 | 53篇 |
2004年 | 46篇 |
2003年 | 37篇 |
2002年 | 40篇 |
2001年 | 4篇 |
2000年 | 8篇 |
1999年 | 12篇 |
1998年 | 11篇 |
1997年 | 10篇 |
1996年 | 13篇 |
1995年 | 4篇 |
1994年 | 11篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1989年 | 7篇 |
1988年 | 3篇 |
1987年 | 6篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1978年 | 8篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 4篇 |
1956年 | 1篇 |
1954年 | 1篇 |
1953年 | 1篇 |
1943年 | 1篇 |
排序方式: 共有767条查询结果,搜索用时 11 毫秒
21.
Albertini AA Clapier CR Wernimont AK Schoehn G Weissenhorn W Ruigrok RW 《Journal of structural biology》2007,158(1):129-133
In order to study the packaging of rabies virus RNA inside the viral nucleocapsid, rabies nucleoprotein was expressed in insect cells. In the cells, it binds to cellular RNA to form long, helical or short circular complexes, depending on the length of the bound RNA. The circular complexes contained from 9 up to 13 N-protomers per ring. Separation of the rings into defined size classes was impossible through regular column chromatographies or gradient centrifugation. The size classes could be separated by native polyacrylamide gel electrophoresis. A large-scale separation was achieved with a 4% native gel using a preparative electrophoresis apparatus. Crystallization trials were set up with N-RNA rings from three size classes and crystals were obtained in all cases. The best diffracting crystals, diffracting up to 6A, contained rings with 11 N-protomers plus an RNA molecule of 99 nucleotides. The diffraction limit was improved to 3.5A by air dehydration prior to flash freezing. 相似文献
22.
Sabine Lederer Erik Lattwein Merle Hanke Karen Sonnenberg Winfried Stoecker ?ke Lundkvist Antti Vaheri Olli Vapalahti Paul K. S. Chan Heinz Feldmann Daryl Dick Jonas Schmidt-Chanasit Paula Padula Pablo A. Vial Raluca Panculescu-Gatej Cornelia Ceianu Paul Heyman Tatjana Av?i?-?upanc Matthias Niedrig 《PLoS neglected tropical diseases》2013,7(4)
In order to detect serum antibodies against clinically important Old and New World hantaviruses simultaneously, multiparametric indirect immunofluorescence assays (IFAs) based on biochip mosaics were developed. Each of the mosaic substrates consisted of cells infected with one of the virus types Hantaan (HTNV), Puumala (PUUV), Seoul (SEOV), Saaremaa (SAAV), Dobrava (DOBV), Sin Nombre (SNV) or Andes (ANDV). For assay evaluation, serum IgG and IgM antibodies were analyzed using 184 laboratory-confirmed hantavirus-positive sera collected at six diagnostic centers from patients actively or previously infected with the following hantavirus serotypes: PUUV (Finland, n = 97); SEOV (China, n = 5); DOBV (Romania, n = 7); SNV (Canada, n = 23); ANDV (Argentina and Chile, n = 52). The control panel comprised 89 sera from healthy blood donors. According to the reference tests, all 184 patient samples were seropositive for hantavirus-specific IgG (n = 177; 96%) and/or IgM (n = 131; 72%), while all control samples were tested negative. In the multiparametric IFA applied in this study, 183 (99%) of the patient sera were IgG and 131 (71%) IgM positive (accordance with the reference tests: IgG, 96%; IgM, 93%). Overall IFA sensitivity for combined IgG and IgM analysis amounted to 100% for all serotypes, except for SNV (96%). Of the 89 control sera, 2 (2%) showed IgG reactivity against the HTNV substrate, but not against any other hantavirus. Due to the high cross-reactivity of hantaviral nucleocapsid proteins, endpoint titrations were conducted, allowing serotype determination in >90% of PUUV- and ANDV-infected patients. Thus, multiparametric IFA enables highly sensitive and specific serological diagnosis of hantavirus infections and can be used to differentiate PUUV and ANDV infection from infections with Murinae-borne hantaviruses (e.g. DOBV and SEOV). 相似文献
23.
24.
Oluyomi Stephen Adeyemi Nthatisi Innocentia Molefe-Nyembe Abiodun Omokehinde Eseola Winfried Plass Oluwatosin Kudirat Shittu Ibrahim Olatunji Yunusa Olubunmi Atolani Ikponmwosa Owen Evbuomwan Oluwakemi J. Awakan Keisuke Suganuma Kentaro Kato 《The Yale journal of biology and medicine》2021,94(2):199
The Trypanosoma spp. cause animal and human trypanosomiasis characterized with appreciable health and economic burden mostly in developing nations. There is currently no effective therapy for this parasitic disease, due to poor drug efficacy, drug resistance, and unwanted toxicity, etc. Therefore, new anti-Trypanosoma agents are urgently needed. This study explored new series of imidazoles for anti-Trypanosoma properties in vitro and in vivo. The imidazoles showed moderate to strong and specific action against growth of T. congolense. For example, the efficacy of the imidazole compounds to restrict Trypanosoma growth in vitro was ≥ 12-fold specific towards T. congolense relative to the mammalian cells. Additionally, the in vivo study revealed that the imidazoles exhibited promising anti-Trypanosoma efficacy corroborating the in vitro anti-parasite capacity. In particular, three imidazole compounds (C1, C6, and C8) not only cleared the systemic parasite burden but cured infected rats after no death was recorded. On the other hand, the remaining five imidazole compounds (C2, C3, C4, C5, and C7) drastically reduced the systemic parasite load while extending survival time of the infected rats by 14 days as compared with control. Untreated control died 3 days post-infection, while the rats treated with diminazene aceturate were cured comparable to the results obtained for C1, C6, and C8. In conclusion, this is the first study demonstrating the potential of these new series of imidazoles to clear the systemic parasite burden in infected rats. Furthermore, a high selectivity index of imidazoles towards T. congolense in vitro and the oral LD50 in rats support anti-parasite specific action. Together, findings support the anti-parasitic prospects of the new series of imidazole derivatives. 相似文献
25.
Jabari S da Silveira AB de Oliveira EC Neto SG Quint K Neuhuber W Brehmer A 《Histochemistry and cell biology》2011,135(1):47-57
One frequent chronic syndrome of Chagas’ disease is megacolon, an irreversible dilation of a colonic segment. Extensive enteric
neuron loss in the affected segment is regarded as key factor for deficient motility. Here, we assessed the quantitative balance
between cholinergic and nitrergic neurons representing the main limbs of excitatory and inhibitory colonic motor innervation,
respectively. From surgically removed megacolonic segments of four patients, each three myenteric wholemounts (from non-dilated
oral, megacolonic and non-dilated anal parts) was immunohistochemically triple-stained for choline acetyltransferase, neuronal
nitric oxide synthase (NOS) and the panneuronal human neuronal protein Hu C/D. Degenerative changes were most pronounced in
the megacolonic and anal regions, e.g. bulked, honeycomb-like ganglia with few neurons which were partly enlarged or atrophic
or vacuolated. Neuron counts from each 15 ganglia of 12 megacolonic wholemounts were compared with those of 12 age- and region-matched
controls. Extensive neuron loss, mainly in megacolonic and anal wholemounts, was obvious. In all three regions derived from
megacolonic samples, the proportion of NOS-positive neurons (control: 55%) was significantly increased: in non-dilated oral
parts to 61% (p = 0.003), in megacolonic regions to 72% (p < 0.001) and in non-dilated anal regions to 78% (p < 0.001). We suggest the chronic dilation of megacolonic specimens to be due to the preponderance of the nitrergic, inhibitory
input to the intestinal muscle. However, the observed neuronal imbalance was not restricted to the dilated regions: the non-dilated
anal parts may be innervated by ascending, cholinergic axons emerging from less affected, more anally located regions. 相似文献
26.
SAM domain-based protein oligomerization observed by live-cell fluorescence fluctuation spectroscopy
Sterile-alpha-motif (SAM) domains are common protein interaction motifs observed in organisms as diverse as yeast and human. They play a role in protein homo- and hetero-interactions in processes ranging from signal transduction to RNA binding. In addition, mutations in SAM domain and SAM-mediated oligomers have been linked to several diseases. To date, the observation of heterogeneous SAM-mediated oligomers in vivo has been elusive, which represents a common challenge in dissecting cellular biochemistry in live-cell systems. In this study, we report the oligomerization and binding stoichiometry of high-order, multi-component complexes of (SAM) domain proteins Ste11 and Ste50 in live yeast cells using fluorescence fluctuation methods. Fluorescence cross-correlation spectroscopy (FCCS) and 1-dimensional photon counting histogram (1dPCH) confirm the SAM-mediated interaction and oligomerization of Ste11 and Ste50. Two-dimensional PCH (2dPCH), with endogenously expressed proteins tagged with GFP or mCherry, uniquely indicates that Ste11 and Ste50 form a heterogeneous complex in the yeast cytosol comprised of a dimer of Ste11 and a monomer of Ste50. In addition, Ste50 also exists as a high order oligomer that does not interact with Ste11, and the size of this oligomer decreases in response to signals that activate the MAP kinase cascade. Surprisingly, a SAM domain mutant of Ste50 disrupted not only the Ste50 oligomers but also Ste11 dimerization. These results establish an in vivo model of Ste50 and Ste11 homo- and hetero-oligomerization and highlight the usefulness of 2dPCH for quantitative dissection of complex molecular interactions in genetic model organisms such as yeast. 相似文献
27.
28.
Marjolein Glas H. Bart van den Berg van Saparoea Stephen H. McLaughlin Winfried Roseboom Fan Liu Gregory M. Koningstein Alexander Fish Tanneke den Blaauwen Albert J. R. Heck Luitzen de Jong Wilbert Bitter Iwan J. P. de Esch Joen Luirink 《The Journal of biological chemistry》2015,290(35):21498-21509
Cell division in Escherichia coli involves a set of essential proteins that assembles at midcell to form the so-called divisome. The divisome regulates the invagination of the inner membrane, cell wall synthesis, and inward growth of the outer membrane. One of the divisome proteins, FtsQ, plays a central but enigmatic role in cell division. This protein associates with FtsB and FtsL, which, like FtsQ, are bitopic inner membrane proteins with a large periplasmic domain (denoted FtsQp, FtsBp, and FtsLp) that is indispensable for the function of each protein. Considering the vital nature and accessible location of the FtsQBL complex, it is an attractive target for protein-protein interaction inhibitors intended to block bacterial cell division. In this study, we expressed FtsQp, FtsBp, and FtsLp individually and in combination. Upon co-expression, FtsQp was co-purified with FtsBp and FtsLp from E. coli extracts as a stable trimeric complex. FtsBp was also shown to interact with FtsQp in the absence of FtsLp albeit with lower affinity. Interactions were mapped at the C terminus of the respective domains by site-specific cross-linking. The binding affinity and 1:1:1 stoichiometry of the FtsQpBpLp complex and the FtsQpBp subcomplex were determined in complementary surface plasmon resonance, analytical ultracentrifugation, and native mass spectrometry experiments. 相似文献
29.
Kyrill S. Rogacev Gunnar H. Heine Günther Silbernagel Marcus E. Kleber Sarah Seiler Insa Emrich Simone Lennartz Christian Werner Adam M. Zawada Danilo Fliser Michael B?hm Winfried M?rz Hubert Scharnagl Ulrich Laufs 《PloS one》2016,11(1)
Background
Impaired renal function causes dyslipidemia that contributes to elevated cardiovascular risk in patients with chronic kidney disease (CKD). The proprotein convertase subtilisin/kexin type 9 (PCSK9) is a regulator of the LDL receptor and plasma cholesterol concentrations. Its relationship to kidney function and cardiovascular events in patients with reduced glomerular filtration rate (GFR) has not been explored.Methods
Lipid parameters including PCSK9 were measured in two independent cohorts. CARE FOR HOMe (Cardiovascular and Renal Outcome in CKD 2–4 Patients—The Forth Homburg evaluation) enrolled 443 patients with reduced GFR (between 90 and 15 ml/min/1.73 m2) referred for nephrological care that were prospectively followed for the occurrence of a composite cardiovascular endpoint. As a replication cohort, PCSK9 was quantitated in 1450 patients with GFR between 90 and 15 ml/min/1.73 m2 enrolled in the Ludwigshafen Risk and Cardiovascular Health Study (LURIC) that were prospectively followed for cardiovascular deaths.Results
PCSK9 concentrations did not correlate with baseline GFR (CARE FOR HOMe: r = -0.034; p = 0.479; LURIC: r = -0.017; p = 0.512). 91 patients in CARE FOR HOMe and 335 patients in LURIC reached an endpoint during a median follow-up of 3.0 [1.8–4.1] years and 10.0 [7.3–10.6] years, respectively. Kaplan-Meier analyses showed that PCSK9 concentrations did not predict cardiovascular events in either cohort [CARE FOR HOMe (p = 0.622); LURIC (p = 0.729)]. Sensitivity analyses according to statin intake yielded similar results.Conclusion
In two well characterized independent cohort studies, PCSK9 plasma levels did not correlate with kidney function. Furthermore, PCSK9 plasma concentrations were not associated with cardiovascular events in patients with reduced renal function. 相似文献30.
Uwe Scheuring Klaus Kollewe Winfried Haase Dieter Schubert 《The Journal of membrane biology》1986,90(2):123-135
Summary The anion transport protein of the human erythrocyte membrane, band 3, was solubilized and purified in solutions of the non-ionic detergent Triton X-100. It was incorporated into spherical lipid bilayers by the following procedure: (1) Dry phosphatidylcholine was suspended in the protein solution. Octylglucopyranoside was added until the milky suspension became clear. (2) The sample was dialyzed overnight against detergentfree buffer. (3) Residual Triton X-100 was removed from the opalescent vesicle suspension by sucrose density gradient centrifugation and subsequent dialysis. Sulfate efflux from the vesicles was studied, under exchange conditions, using a filtration method. Three vesicle subpopulations could be distinguished by analyzing the time course of the efflux. One was nearly impermeable to sulfate, and efflux from another was due to leaks. The largest subpopulation, however, showed transport characteristics very similar to those of the anion transport system of the intact erythrocyte membrane: transport numbers (at 30°C) close to 20 sulfate molecules per band 3 and min, an activation energy of approx. 140 kJ/mol, a pH maximum at pH 6.2, saturation of the sulfate flux at sulfate concentrations around 100mm, inhibition of the flux by H2DIDS and flufenamate (approx.K
l-values at 30°C: 0.1 and 0.7 m, respectively), and right-side-out orientation of the transport protein (as judged from the inhibition of sulfate efflux by up to 98% by externally added H2DIDS). Thus, the system represents, for the first time, a reconstitution of all the major properties of the sulfate transport across the erythrocyte membrane. 相似文献