全文获取类型
收费全文 | 6872篇 |
免费 | 490篇 |
出版年
2021年 | 36篇 |
2020年 | 38篇 |
2018年 | 90篇 |
2017年 | 96篇 |
2016年 | 152篇 |
2015年 | 241篇 |
2014年 | 301篇 |
2013年 | 305篇 |
2012年 | 419篇 |
2011年 | 442篇 |
2010年 | 275篇 |
2009年 | 184篇 |
2008年 | 343篇 |
2007年 | 311篇 |
2006年 | 284篇 |
2005年 | 296篇 |
2004年 | 270篇 |
2003年 | 249篇 |
2002年 | 252篇 |
2001年 | 206篇 |
2000年 | 264篇 |
1999年 | 175篇 |
1998年 | 72篇 |
1997年 | 51篇 |
1996年 | 62篇 |
1995年 | 50篇 |
1994年 | 53篇 |
1993年 | 43篇 |
1992年 | 118篇 |
1991年 | 121篇 |
1990年 | 113篇 |
1989年 | 69篇 |
1988年 | 102篇 |
1987年 | 84篇 |
1986年 | 76篇 |
1985年 | 81篇 |
1984年 | 76篇 |
1983年 | 56篇 |
1982年 | 54篇 |
1981年 | 47篇 |
1980年 | 37篇 |
1979年 | 68篇 |
1978年 | 39篇 |
1977年 | 54篇 |
1975年 | 48篇 |
1973年 | 46篇 |
1972年 | 37篇 |
1971年 | 42篇 |
1969年 | 35篇 |
1968年 | 35篇 |
排序方式: 共有7362条查询结果,搜索用时 31 毫秒
991.
S Jacobs C Schilf F Fliegert S Koling Y Weber A Schürmann H G Joost 《FEBS letters》1999,456(3):384-388
The novel ARF-like GTPase ARL7 is a close relative of ARL4 and ARL6 (71% and 59%) identical amino acids). A striking characteristic of these GTPases is their basic C-terminus which, when fused to the C-terminus of green fluorescent protein (GFP), targets the constructs to the nucleus of transfected COS-7 cells. Full length ARL4 was detected in both nuclear and extranuclear compartments, whereas a construct of ARL4 lacking its C-terminus was excluded from the nucleus. Nucleotide exchange rates of recombinant ARL4, ARL6 and ARL7 were similar and appeared considerably higher than those of other members of the ARF family (ARF1, ARP). It is concluded that ARL4, ARL6 and ARL7 form a subgroup within the ARF family with similar, possibly nuclear, function. 相似文献
992.
Cristina Risi Luisa U. Schäfer Betty Belknap Ian Pepper Howard D. White Gunnar F. Schröder Vitold E. Galkin 《Structure (London, England : 1993)》2021,29(1):50-60.e4
- Download : Download high-res image (513KB)
- Download : Download full-size image
993.
994.
995.
H Sch?fer W Clauss H H?rnicke 《Comparative biochemistry and physiology. A, Comparative physiology》1984,79(3):387-392
The distal rabbit colon was used as a model to investigate the influence of the cationophore Salinomycin in vivo with a single-pass perfusion, and in vitro with a modified Ussing chamber technique. For in vivo experiments with labelled 14C-PEG as a volume marker in the perfusate, a dose of 10E-4 mol/l Salinomycin was used. Net water (53 microliters/h/cm), net chloride (3 mumol/h/cm) and net sodium (3.6 mumol/h/cm) absorption was not significantly influenced, but net potassium secretion (-3 mumol/h/cm) was decreased to zero and transepithelial potential (PD) reduced from -45 mV to -33 mV. 10E-4 mol/l Salinomycin, applied in vitro on the muscosal side, decreased PD in 80 min and 10E-3 mol/l in 30 min from 18 mV to zero. Both concentrations decreased the short-circuit current (Isc = 77 microA/cm2) in 60 min, respectively 30 min to 40 microA/cm2. After 60 min mucosal 10E-4 mol/l Salinomycin the Isc increased, resulting from a transepithelial conductance (Gt) increase from 3 to 40 mS/cm2. A dose-related effect was present on PD, Isc and Gt at concentrations between 10E-7 and 10E-6 mol/l. The unidirectional 22Na fluxes were increased to 20 times the control values and net Na transport disappeared. We conclude that Salinomycin when applied in usual doses (10E-4 mol/l) as a coccidiostatic feed additive, profoundly affects colonic electrolyte transport. 相似文献
996.
Zusammenfassung Die proximalen Kollateralen der dorsalen Riesenfasern des Regenwurms wurden in Serienschnitten vom Soma bis zum Eintritt in die Riesenfaser verfolgt und im Hinblick auf ihre Feinstruktur und ihre synaptischen Kontakte Untersucht. Es finden sich sowohl chemische als auch elektrische Synapsen. Ihre Feinstruktur wird mit der bekannter Synapsen anderer Wirbellosen und Wirbeltiere verglichen. In beiden Riesenfasersystemen kommen efferente chemische Synapsen mit feinen postsynaptischen Verzweigungen vor, die anscheinend von Bauchmark-Motoneuronen stammen. Das Axon der medianen Riesenfaser weist darüber hinaus nur noch eine elektrische Synapse mit den Rieseninterneuronen auf. Demgegenüber erhalten die Kollateralen der lateralen Riesenfasern zahlreiche Afferenzen, die zum Teil als sensorische Fasern der Epidermis, multisegmentale Fasern der Hauptfaserzüge und Rieseninterneurone identifiziert werden konnten. Weitere Afferenzen stammen vermutlich von unisegmentalen Interneuronen her. Beide lateralen Riesenzellaxone bilden außerdem miteinander eine elektrische Chiasma-Synapse mit besonderen Membraneinfaltungen.
Ultrastructure of the dorsal giant fibre system in the ventral nerve cord of the earthwormII. Synaptic connections of the proximal collaterals of the giant fibres
Summary The proximal collaterals of the dorsal giant fibres of the earthworm were traced through serial sections from the cell bodies to the giant axons. Their structure and synaptic connections were examined. There are chemical as well as electrical synapses. Their fine structure is compared to that of other known invertebrate and vertebrate synapses. Both giant fibre systems have efferent chemical connections with thin postsynaptic arborizations which probably belong to ventral cord motoneurons. Moreover the median giant axon is connected by an electrical synapse with the giant interneurons. The lateral giant collaterals on the contrary receive many afferences through chemical synapses which were partly identified as sensory fibers from the epidermis, multisegmental axons from the main fibre bundles or giant interneurones. Other afferences probably come from unisegmental interneurones. In addition both lateral giant axons form an electrical chiasma synapse with special membrane folds.
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft Gu 117/1. 相似文献
997.
998.
999.
1000.
The C-terminal non-collagenous domain of the surfactant glycoprotein SP-A was shown to be essential for its correct folding and assembly, as judged by the secretion of various deletion mutants transiently expressed in COS cells. A deletion mutant coding for this domain was successfully secreted while the expression of the collagenous domain only did not lead to any detectable secretion. Deletion mutants lacking small parts of the non-collagenous domain interfered more or less with the correct folding and assembly of the molecule, thus either reducing or inhibiting the secretion. These data suggest that three prefolded non-collagenous domains register and act as a nucleation center for the folding of the collagenous triple helix which proceeds in a zipper-like fashion towards the N-terminus. 相似文献