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1.
Changes in DNA supertwist as a response of Bacillus subtilis towards different kinds of stress 总被引:1,自引:0,他引:1
Abstract The silent parD ( kis/kid ) stability operon of plasmid R1 is normally repressed by the co-ordinated action of the Kis and Kid proteins. In this report it is shown that a mutation in repA , the gene of the plasmid replication protein, that reduces two-fold the copy number of the plasmid, leads to the derepression of the parD system. This derepression can be prevented by a suppressor mutation in copB, a copy number control gene of plasmid R1, that increases the efficiency of replication of the repA mutant. Derepression of the wild-type parD system leads to high plasmid stability. These data show the activation of a plasmid stability operon by a mutation that reduces the efficiency of wild-type plasmid replication. 相似文献
2.
Rudolf Werner Todd Miller Roobik Azarnia Gerhard Dahl 《The Journal of membrane biology》1985,87(3):253-268
Summary mRNA from estrogen-stimulated rat myometrium, a tissue known to upregulate cell-cell channels in response to this hormone, was microinjected intoXenopus laevis oocytes. The oocytes had been freed from covering layers of follicle cells and vitelline to allow direct cell membrane interactions when paired. About 4 hours after the mRNA injection, paired oocytes become electrically coupled. This coupling was due to the presence of typical cell-cell channels characterized by size-limited intercellular tracer flux, the presence of gap junctions at the oocyte-oocyte interface, and the reversible uncoupling that occurred in the presence of carbon dioxide. The induction of new cell-cell channels in the oocyte membrane was observed against a zero background or a low level of endogenous coupling, depending on the maturation stage of the oocytes. The time course of development of cell-cell coupling after the microinjection of mRNA was determined. The mRNA capable of inducing cell-cell coupling was confined to an intermediate size class when fractionated on a sucrose gradient. 相似文献
3.
Hansen T Arnfors L Ladenstein R Schönheit P 《Extremophiles : life under extreme conditions》2007,11(1):105-114
Recently, unusual non-regulated ATP-dependent 6-phosphofructokinases (PFK) that belong to the PFK-B family have been described
for the hyperthermophilic archaea Desulfurococcus amylolyticus and Aeropyrum pernix. Putative homologues were found in genomes of several archaea including the hyperthermophilic archaeon Methanocaldococcus jannaschii. In this organism, open reading frame MJ0406 had been annotated as a PFK-B sugar kinase. The gene encoding MJ0406 was cloned
and functionally expressed in Escherichia coli. The purified recombinant enzyme is a homodimer with an apparent molecular mass of 68 kDa composed of 34 kDa subunits. With
a temperature optimum of 85°C and a melting temperature of 90°C, the M. jannaschii nucleotide kinase represents one of the most thermoactive and thermostable members of the PFK-B family described so far.
The recombinant enzyme was characterized as a functional nucleoside kinase rather than a 6-PFK. Inosine, guanosine, and cytidine
were the most effective phosphoryl acceptors. Besides, adenosine, thymidine, uridin and xanthosine were less efficient. Extremely
low activity was found with fructose-6-phosphate. Further, the substrate specificity of closely related PFK-Bs from D. amylolyticus and A. pernix were reanalysed. 相似文献
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Background
The gold standard for the diagnosis of schistosomiasis is the detection of the parasite''s characteristic eggs in urine, stool, or rectal and bladder biopsy specimens. Direct detection of eggs is difficult and not always possible in patients with low egg-shedding rates. Confocal laser scanning microscopy (CLSM) permits non-invasive cell imaging in vivo and is an established way of obtaining high-resolution images and 3-dimensional reconstructions. Recently, CLSM was shown to be a suitable method to visualize Schistosoma mansoni eggs within the mucosa of dissected mouse gut. In this case, we evaluated the suitability of CLSM to detect eggs of Schistosoma haematobium in a patient with urinary schistosomiasis and low egg-shedding rates.Methodology/Principal Findings
The confocal laser scanning microscope used in this study was based on a scanning laser system for imaging the retina of a living eye, the Heidelberg Retina Tomograph II, in combination with a lens system (image modality). Standard light cystoscopy was performed using a rigid cystoscope under general anaesthesia. The CLSM endoscope was then passed through the working channel of the rigid cystoscope. The mucosal tissue of the bladder was scanned using CLSM. Schistoma haematobium eggs appeared as bright structures, with the characteristic egg shape and typical terminal spine.Conclusion/Significance
We were able to detect schistosomal eggs in the urothelium of a patient with urinary schistosomiasis. Thus, CLSM may be a suitable tool for the diagnosis of schistosomiasis in humans, especially in cases where standard diagnostic tools are not suitable. 相似文献9.
Maria Guadalupe Vizoso Pinto Josefina Maria Villegas Jan Peter Rudolf Haase Jürgen Haas Amelie Sophia Lotz Ania Carolina Muntau Armin Baiker 《Proteomics》2009,9(23):5303-5308
The GC content is highly variable among the genomes of different organisms. It has been shown that recombinant gene expression in mammalian cells is much more efficient when GC‐rich coding sequences of a certain protein are used. In order to study protein–protein interactions in Varicella zoster virus, a GC‐low herpesvirus, we have developed a novel luminescence‐based maltose‐binding protein pull‐down interaction screening system (LuMPIS) that is able to overcome the impaired protein expression levels of GC‐low ORFs in mammalian expression systems. 相似文献
10.
Mingels AM Joosen IA Versteylen MO Laufer EM Winkens MH Wildberger JE Van Dieijen-Visser MP Hofstra L 《PloS one》2012,7(4):e35059