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排序方式: 共有1101条查询结果,搜索用时 15 毫秒
1.
2.
G. Giacomo Consalez Carol L. Stayton Nelson B. Freimer Ponmani Goonewardena W. Ted Brown T. Conrad Gilliam Stephen T. Warren 《Genomics》1992,12(4):710-714
Human Xq28 is highly gene dense with over 27 loci. Because most of these genes have been mapped by linkage to polymorphic loci, only one of which (DXS52) is informative in most families, a search was conducted for new, highly polymorphic Xq28 markers. From a cosmid library constructed using a somatic cell hybrid containing human Xq27.3----qter as the sole human DNA, a human-insert cosmid (c346) was identified and found to reveal variation on Southern blot analyses with female DNA digested with any of several different restriction endonucleases. Two subclones of c346, p346.8 and p346.T, that respectively identify a multiallelic VNTR locus and a frequent two-allele TaqI polymorphism were isolated. Examination of 21 unrelated females showed heterozygosity of 76 and 57%, respectively. These two markers appeared to be in linkage equilibrium, and a combined analysis revealed heterozygosity in 91% of unrelated females. Families segregating the fragile X syndrome with key Xq28 crossovers position this locus (designated DXS455) between the proximal Xq28 locus DXS296 (VK21) and the more distal locus DXS374 (1A1), which is proximal to DXS52. DXS455 is therefore the most polymorphic locus identified in Xq28 and will be useful in the genetic analysis of this gene dense region, including the diagnosis of nearby genetic disease loci by linkage. 相似文献
3.
Isolation of the calmodulin-dependent protein kinase system from rabbit skeletal muscle sarcoplasmic reticulum 总被引:2,自引:0,他引:2
A calmodulin-dependent protein kinase system from the sarcoplasmic reticulum was dissolved in Nonidet P40, adsorbed to a CaM affinity column in the presence of Ca2+ and eluted in the presence of EGTA. The purified fraction contained major proteins of 60 and 20 kDa and minor components of 89 and 34 kDa, all of which were phosphorylated with dependencies on Ca2+, CaM, ATP and pH similar to those observed in the sarcoplasmic reticulum. Differences in the phosphopeptides produced by partial proteolysis of the individual phosphoproteins indicated that they are distinct entities. 125I-CaM labeled only the 60 kDa protein, suggesting that it is a kinase. 相似文献
4.
Leandro Medrano Giacomo Bernardi Jérome Couturier Bernard Dutrillaux Giorgio Bernardi 《Chromosoma》1988,97(2):178-183
The diploid chromosome number of the Chinese raccoon dog varies from 54 (no B chromosomes) to 58 (4 B chromosomes). The B chromosomes are totally heterochromatic. An electron microscopic study was made of the synaptonemal complexes (SC) in spermatocytes of these animals. The SC karyotype consists of 27 regular chromosome pairs (autosomes and the sex chromosomes) plus the B chromosomes. The Bs pair effectively with one another at pachytene, but the SC axes of the B chromosomes are much denser than those of the A chromosomes. Depending on the number of Bs, both bivalents and multivalents have been observed. When three B chromosomes are present in a cell, parallel alignment of all three SCs can be seen. Formation of multivalents indicates high homology among these supernumerary heterochromatic chromosomes. Fusiform bulges are found along unpaired regions of all chromosomes which are particularly pronounced in diplotene. 相似文献
5.
Derek G. Smyth Frederick C. Battaglia Giacomo Meschia 《The Journal of general physiology》1961,44(5):889-898
A simple method is described for the measurement of pH changes in hemoglobin solutions on oxygenation and reduction. Data are presented establishing the absence of a Bohr effect in p-chloromercuribenzoate [PCMB] treated hemoglobin. The influence of a number of sulfhydryl inhibitors on the Bohr effect of a hemoglobin solution is reported and an interpretation based on steric factors in the protein is proposed. 相似文献
6.
Roberto Bovara Giacomo Carrea Sergio Riva Francesco Secundo 《Biotechnology letters》1996,18(3):305-308
Summary Cholic acid (3,7,12-trihydroxy-5-cholanoic acid) was completely and selectively transformed into 12-ketoursodeoxycholic acid (3,7-dihydroxy-12-oxo-5-cholanoic acid) by means of two consecutive enzymatic steps catalyzed, the first, by 7- and 12-hydroxysteroid dehydrogenase and, the second, by 7-hydroxysteroid dehydrogenase. Coenzyme regeneration was carried out with -ketoglutarate-glutamate dehydrogenase and glucose-glucose dehydrogenase, respectively. 相似文献
7.
Vita Peri Boris Ajdukovic Paul Holland Balwant S. Tuana 《Molecular and cellular biochemistry》1994,130(1):57-65
Dystrophin is a high molecular weight protein present at low abundance in skeletal, cardiac and smooth muscle and in trace amounts in brain. In skeletal muscle, dystrophin is uniformly distributed along the inner surface of the plasma membrane. Biochemical fractionation studies have shown that all detectable skeletal muscle dystrophin is tightly associated with a complex of wheat germ agglutinin (WGA)-binding and concanavalin A (Con A) binding sarcolemmal glycoproteins. Absence of dystrophin is the primary biochemical defect in patients with Duchenne muscular dystrophy and leads to segmental necrosis of their skeletal myofibers. Although present in similar amounts in normal cardiac and skeletal muscle, the absence of dystrophin from cardiac muscle has less severe effects on the survival of cardiac cells. We have therefore examined whether there are differences in the properties of cardiac and skeletal dystrophin. We report that in contrast to skeletal muscle, cardiac dystrophin is distributed between distinct pools: a soluble cytoplasmic pool, a membrane-bound pool not associated with WGA-binding glycoproteins and a membrane-bound pool associated with WGA-binding glycoproteins. Cardiac dystrophin was not associated with any Con A binding glycoproteins. Immunohistochemical localization studies in isolated ventricular myocytes reveal a distinct punctate staining pattern for dystrophin, approximating to the level of the transverse tubule/Z-line and contrasting with the uniform sarcolemmal staining reported for skeletal muscle fibers. The distinct properties of cardiac dystrophin suggest unique roles for this protein in cardiac versus skeletal muscle function.Abbreviations Dys
Dystrophin
- T-tubule
Transverse tubule
- SDS-PAGE
Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis
- WGA
Wheat Germ Agglutinin
- Con A
Concanavalin A
- DHP
Dihydropyridine receptor
- FITC
Fluorescein Isothiocyanate Conjugate
- NAG
N-Acetyl-D-Glucosamine
- NP-40
NONIDET P-40
- PBS
Phosphate-Buffered Saline
- TBST
Tris Buffered Saline-Tween 相似文献
8.
Summary The neuro-endocrine cells of fish skin and respiratory surfaces, and their bioactive secretion as far as is known, are reviewed, and compared with similar elements in tetrapods, particularly amphibians. In the skin of teleost fish, immunohistochemistry has shown that Merkel cells react for serotonin, neuron-specific enolase and enkephalins. The pharmacology is not established in dipnoans or lampreys. In some teleosts, neuromasts react for substance P and leu-enkephalins; substance P is also reported from some ampullary organs (electroreceptors). Taste buds of teleosts may react for enkephalin and substance P. Basal cells of taste buds react for serotonin and neuron-specific enolase. Some unicellular skin glands of teleosts express bioactive compounds, including serotonin and some peptides; this ectopic expression is paralleled in amphibian skin glands. The dipnoan Protopterus has innervated pulmonary neuro-endocrine cells in the pneumatic duct region with dense-cored vesicles. In Polypterus and Amia the lungs have serotonin-positive neuro-endocrine cells that are apparently not innervated. In fish gills, a closed type of neuro-endocrine cell reacts for serotonin, an open type for enkephalins and some calcium-binding proteins (calbindin, calmodulin and S-100 protein). The functions of neuro-endocrine cells in fishes await investigation, but it is assumed they are regulatory. 相似文献
9.
Maurizio Grimaldi Giacomo Pozzoli Pierluigi Navarra Paolo Preziosi Gennaro Schettini 《Journal of neurochemistry》1994,63(1):344-350
Abstract: In this study we analyzed the involvement of the cyclic AMP (cAMP)-protein kinase A system in the regulation of interleukin 6 production by cultured cortical astrocytes. Vasoactive intestinal peptide strongly increased, in a dose-dependent manner, interleukin 6 production. This effect was reduced when protein kinase A was blocked by KT-5720; it was not affected by calphostin C, a protein kinase C inhibitor. Forskolin caused a concentration-dependent increase in interleukin 6 release that was also inhibited by KT-5720. Because prostaglandins are believed to play a role in interleukin 6 production, we tried to determine whether the stimulatory effects of vasoactive intestinal peptide and forskolin on cytokine release might be mediated by stimulation of prostaglandin production in cortical astrocytes. Vasoactive intestinal peptide did not increase the production of either prostaglandin E2 or F2α. Conversely, forskolin concentration-dependently stimulated the production of both prostaglandins, an effect that was blocked by indomethacin. Indomethacin did not affect either vasoactive intestinal peptide- or forskolin-stimulated interleukin 6 production. To exclude the possibility that prostaglandins participate in interleukin 6 production induced by forskolin, we tested prostaglandins E2 and F2α. The former was completely ineffective in eliciting the cytokine production, whereas prostaglandin F2α slightly increased interleukin 6 production only at the highest concentrations. 8-Bromo-cAMP and dibutyryl-cAMP stimulated interleukin 6 production to a lesser extent than vasoactive intestinal peptide and forskolin. In conclusion, we provide evidence that vasoactive intestinal peptide increases interleukin 6 production by astrocytes through the stimulation of the cAMP-protein kinase A pathway, an effect that is reproduced by cAMP analogues. In addition, we point out that prostaglandins are not involved in vasoactive intestinal peptide- and forskolin-mediated induction of interleukin 6 production in cultured astrocytes. 相似文献
10.
Homing to a more or less permanent scar after each foragingexcursion is a common movement pattern among intertidal gastropodsand chitons; however, details of the timing and spacing of foragingactivity have been investigated only in a few species. The presentstudy analyzes the short-term behavior of the limpet Patellarustica along the Tyrrhenian coast, Italy, using a motographictechnique to assess the fine organization of its foraging duringfavorable periods of sea roughness. P. rustica becomes activeonce the upper midlittoral is well splashed. It alternates foragingexcursions and resting at home with a periodicity slightly longerthan 12 h, suggesting a tidal-diel pattern. However, periodogramanalysis of the sea level oscillations during the study periodsrevealed no such rhythmicity because tidal oscillations werehidden by irregular variations caused by waves. As a resultof this time partitioning, limpets move, on average, less than50% of their potential activity time. Time partitioning maybe highly adaptive in reducing potential risks. Nevertheless,in the absence of clear external driving cues, the significanceof a very regular and apparently tidal pattern, fairly synchronousamong the different specimens, remains to be explained. Theactivity of P. rustica during each excursion is organized intothree parts: the outgoing journey during which grazing activityprogressively increases, a central part characterized by intensegrazing, and the return characterized by fast displacement anda more or less consistent trail following. Limpets head forrandom directions to reach foraging grounds in successive excursions,showing only a slight avoidance of the direction taken duringthe previous outward journey. This pattern produces a spatialscattering of grazing activity, allowing efficient exploitationof grazing areas distributed radially around home during subsequentexcursions. 相似文献