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91.
Andreas Kandelbauer Angelika Erlacher Artur Cavaco-Paulo 《Biocatalysis and Biotransformation》2013,31(5-6):331-339
The kinetics of laccase-catalyzed transformation of the azo-dye Diamond Black PV 200 (CI Mordant Black 9) and various related synthesized derivatives were analyzed for dependence on pH and substrate structure. The reaction mixture of Diamond Black PV 200 was analyzed by HPLC/MS–MS and it was shown that upon laccase oxidation, reactive chinoid fragments of lower molecular weight were formed. These may further oligomerize as indicated by the appearance of a number of compounds with increased molecular weight. The pH optimum for the decolorization was pH 5 for Diamond Black PV 200 which did not change significantly when the substitution pattern of its basic structure was varied. Biodegradability, however, was strongly dependent on the structure of the dyes. 相似文献
92.
93.
Rosentreter A Hofmann A Xavier CP Stumpf M Noegel AA Clemen CS 《Experimental cell research》2007,313(5):878-895
The actin interaction of coronin 3 has been mainly documented by in vitro experiments. Here, we discuss coronin 3 properties in the light of new structural information and focus on assays that reflect in vivo roles of coronin 3 and its impact on F-actin-associated functions. Using GFP-tagged coronin 3 fusion proteins and RNAi silencing we show that coronin 3 has roles in wound healing, protrusion formation, cell proliferation, cytokinesis, endocytosis, axonal growth, and secretion. During formation of cell protrusions actin accumulation precedes the focal enrichment of coronin 3 suggesting a role for coronin 3 in events that follow the initial F-actin assembly. Moreover, we show that coronin 3 similar to other coronins interacts with the Arp2/3-complex and cofilin indicating that this family in general is involved in regulating Arp2/3-mediated events. 相似文献
94.
The Tat (twin-arginine translocation) system from Escherichia coli transports folded proteins with N-terminal twin-arginine signal peptides across the cytoplasmic membrane. The influence of general chaperones on Tat substrate targeting has not been clarified so far. Here we show that the chaperones SlyD and DnaK bind to a broad range of different Tat signal sequences in vitro and in vivo. Initially, SlyD and GroEL were purified from DnaK-deficient extracts by their affinity to various Tat signal sequences. Of these, only SlyD bound Tat signal sequences also in the presence of DnaK. SlyD and DnaK also co-purified with Tat substrate precursors, demonstrating the binding to Tat signal sequences in vivo. Deletion of dnaK completely abolished Tat-dependent translocation of CueO, but not of DmsA, YcdB, or HiPIP, indicating that DnaK has an essential role specifically for CueO. DnaK was not required for stability of the CueO precursor and thus served in some essential step after folding. A CueO signal sequence fusion to HiPIP was Tat-dependently transported without the need of DnaK, indicating that the mature domain of CueO is responsible for the DnaK dependence. The overall results suggest that SlyD and DnaK are in the set of chaperones that can serve as general Tat signal-binding proteins. DnaK has additional functions that are indispensable for the targeting of CueO. 相似文献
95.
Thomas?R.?R?thel Jürgen?F.?Leikert Angelika?M.?Vollmar Verena?M.?DirschEmail author 《Biological procedures online》2003,5(1):136-142
Here we describe in more depth the previously published application of the fluorescent probe 4,5-diaminofluorescein (DAF-2)
in order to reliably measure low levels of nitric oxide (NO) as released from human endothelial cells invitro. The used approach is based on the following considerations a) use low concentrations of DAF-2 (0.1 μM) in order to reduce
the contribution of DAF-2 auto-fluorescence to the measured total fluorescence, and b) subtract the DAF-2 auto-fluorescence
from the measured total fluorescence. The advantage of this method is the reliable quantification of NO in a biological system
in the nanomolar range once thoroughly validated. Here we focus in addition to the previous publication (Leikertet al.,FEBS Lett 2001, 506:131–134) on aspects of validation procedures as well as limitations and pitfalls of this method.
Published: June 2, 2003 相似文献
96.
Peracino B Wagner C Balest A Balbo A Pergolizzi B Noegel AA Steinert M Bozzaro S 《Traffic (Copenhagen, Denmark)》2006,7(1):22-38
Dictyostelium amoebae are professional phagocytes, which ingest bacteria as the principal source of food. We have cloned the Dictyostelium homologue of human natural resistance-associated membrane protein 1 (Nramp1) [solute carrier family 11 member 1 (Slc11a1)], an endo-lysosomal membrane protein that confers on macrophages resistance to infection by a variety of intracellular bacteria and protozoa. The Dictyostelium Nramp1 gene encodes a protein of 53 kDa with 11 putative transmembrane domains. The Nramp1 gene is transcribed during the growth-phase and downregulated to barely detectable levels upon starvation. To gain insights into their intracellular localization, we fused Nramp1 or the vatB subunit of the V-H(+)ATPase with green fluorescent protein and expressed in cells. Green fluorescent protein-vatB was inserted in membranes of all acidic compartments and the contractile vacuole network and decorated macropinosomes and phagosomes. Green fluorescent protein-Nramp1 decorated macropinosomes and phagosomes, in addition to intracellular vesicular compartments positive for endosomal SNARE protein Vti1 or vacuolin, a marker of the exocytic pathway. Nramp1 disruption generated mutants that were more permissive hosts than wild-type cells for intracellular growth of Legionella pneumophila and Micobacterium avium. Nramp1 overexpression protected cells from L. pneumophila infection. Evidence is provided that Nramp1 transports metal cations out of the phagolysosome in an ATP-dependent process and that L. pneumophila and M. avium use different mechanisms to neutralize Nramp1 activity. 相似文献
97.
Alex Soltermann Angelika Ernst Didier Leroy Rolf A. Stahel Susan M. Gasser 《Experimental cell research》1999,249(2):308
DNA topoisomerase II (topo II) is the target of many anticancer drugs and is often altered in drug-resistant cell lines. In some tumor cell lines truncated isoforms of topo IIα are localized to the cytoplasm. To study the localization and function of individual enzyme domains, we have epitope-tagged several fragments of human topo IIα and expressed them by retroviral infection of rodent and human cells. We find that fusion of the topo II fragments to the hydrophobic tail of human liver cytochrome b5 anchors the fusion protein to the outer face of cytoplasmic membranes, as determined by colocalization with calnexin and selective detergent permeabilization. Moreover, whereas the minimal ATPase domain (aa 1–266) is weakly and diffusely expressed, addition of the cytb5 anchor (1–266-b5) increases its steady-state level 16-fold with no apparent toxicity. Similar results are obtained with the complete ATPase domain (aa 1–426). A C-terminal domain (aa 1030–1504) of human topo IIα containing an intact dimerization motif is stably expressed and accumulates in the nucleus. Fusion to the cytb5 anchor counteracts the nuclear localization signal and relocalizes the protein to cytoplasmic membranes. In conclusion, we describe a technique that stabilizes and targets retrovirally expressed proteins such that they are exposed on the cytoplasmic surface of cellular membranes. This approach may be of general use for regulating the nuclear accumulation of drugs or proteins in living cells. 相似文献
98.
99.
The Perceived Temperature (PT) is an equivalent temperature based on a complete heat budget model of the human body. It has
proved its suitability for numerous applications across a wide variety of scales from micro to global and is successfully
used both in daily forecasts and climatological studies. PT is designed for staying outdoors and is defined as the air temperature
of a reference environment in which the thermal perception would be the same as in the actual environment. The calculation
is performed for a reference subject with an internal heat production of 135 W m−2 (who is walking at 4 km h−1 on flat ground). In the reference environment, the mean radiant temperature equals the air temperature and wind velocity
is reduced to a slight draught. The water vapour pressure remains unchanged. Under warm/humid conditions, however, it is implicitly
related to a relative humidity of 50%. Clothing is adapted in order to achieve thermal comfort. If this is impossible, cold
or heat stress will occur, respectively. The assessment of thermal perception by means of PT is based on Fanger’s Predicted
Mean Vote (PMV) together with additional model extensions taking account of stronger deviations from thermal neutrality. This
is performed using a parameterisation based on a two-node model. In the cold, it allows the mean skin temperature to drop
below the comfort value. In the heat, it assesses additionally the enthalpy of sweat-moistened skin and of wet clothes. PT
has the advantages of being self-explanatory due to its deviation from air temperature and being—via PMV—directly linked to
a thermo-physiologically-based scale of thermal perception that is widely used and has stood the test of time. This paper
explains in detail the basic equations of the human heat budget and the coefficients of the parameterisations. 相似文献
100.