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1.
Regulation of Protein Synthesis during Photomorphogenesis of Gametophytes of the Fern Onoclea sensibilis 下载免费PDF全文
Gametophytes of the fern Onoclea sensibilis grow as filaments in the dark and in red light and become planar in blue light. Pulse-labeling 4-day-old gametophytes with [35S]methionine at different times after transfer to dark, red, and blue light environments revealed higher rates of amino acid uptake and protein synthesis in blue light than in red light or in the dark. Characterization of the extant and newly synthesized soluble proteins by one- and two-dimensional gel electrophoresis showed that the patterns of protein accumulation and synthesis in gametophytes exposed to short periods of red or blue light were qualitatively indistinguishable from those of gametophytes maintained in the dark. However, some striking increases and decreases in the levels of certain polypeptides were noted and these changes were accentuated during continued growth of gametophytes in the different environments. The results show that photomorphogenesis of gametophytes of O. sensibilis is associated with quantitative rather than qualitative changes in the population of mRNAs available for translation. 相似文献
2.
A J Grant P J Russell D Raghavan 《Biochemical and biophysical research communications》1989,162(1):308-315
Elastase activities in intact human bladder cancer cell lines, established from three patients, were measured using a fluorogenic substrate highly specific for elastase, under conditions of physiological pH and ionic strength. This method allowed separation of cell-associated from secreted enzyme activity. As secreted elastase accounted for only 8% of the total, we concluded that the elastases were present at the cell surface. Inhibition studies using extracts of cell-surface elastases showed them to be serine proteinases which were also inhibited by alpha 1-antitrypsin. Partially purified fractions showing the highest specific activity towards the fluorogenic substrate hydrolysed insoluble elastin thus confirming the presence of elastases. This is the first time that elastase activity has been demonstrated in human bladder cancer cells and may represent a mechanism involved in tumour invasion. 相似文献
3.
C D Warren J Alroy B Bugge P F Daniel S S Raghavan E H Kolodny J J Lamar R W Jeanloz 《FEBS letters》1986,195(1-2):247-252
High-pressure liquid chromatography analysis of oligosaccharides from placentas allowed the diagnosis of alpha-mannosidosis in three litters of kittens. The chromatography also afforded a detailed comparison of the oligosaccharide pattern and levels in placenta, liver, brain, urine and ocular fluid of the affected animals. In all cases, two series of compounds were observed, with one or two residues of N-acetylglucosamine at the reducing terminus, respectively, and between two and nine mannose residues. This pattern is unlike that of human mannosidosis, and resembles that of ruminants, except that the major oligosaccharide contains three mannose residues instead of two. 相似文献
4.
E E Grebner D A Mansfield S S Raghavan E H Kolodny A d'Azzo E F Neufeld L G Jackson 《American journal of human genetics》1986,38(4):505-514
Two abnormalities of beta-hexosaminidase A (HEX A) activity are described. One, found in two unrelated Jewish children, was characterized by the complete absence of HEX A activity in serum, but low levels of activity in leukocytes and fibroblasts using artificial substrate. The other, found in a non-Jewish man, was characterized by uniformly low levels of HEX A activity in leukocytes, fibroblasts, and serum against artificial substrate. In all cases, the pH optimum of HEX A was normal, there was no increased lability at 37 degrees C, and no inhibitor was detected to account for the deficiency of activity. Cultured fibroblasts of these individuals were capable of synthesizing and processing alpha- and beta-subunits of HEX A and capable of cleaving GM2 ganglioside. The patients, ranging in age from 6 to 30 years, are clinically normal. They are probably genetic compounds carrying the classical Tay-Sachs gene and a differently mutated allele that imparts the anomalous phenotypic features observed. 相似文献
5.
Brian C. Varnum Srinivasa T. Reddy Raymond A. Koski Harvey R. Herschman 《Journal of cellular physiology》1994,158(1):205-213
Murine TIS7 and TIS21 cDNAs were cloned from phorbol ester-induced Swiss 3T3 cells. The cognate rat cDNAs. PC4 and PC3, were cloned from nerve growth factor (NGF)-treated PC12 pheochromocytoma cells. The TIS7/PC4 and TIS21/PC3 primary response genes are rapidly and transiently induced in response to serum, phorbol esters, and polypeptide growth factors in quiescent Swiss 3T3 cells and by NGF and other ligands in PC12 cells. In both 3T3 and PC12 cells the appearance of the TIS21/PC3 message precedes that of TIS7/PC4 message following ligand stimulation, suggesting that the TIS21/PC3 protein is likely to be synthesized more rapidly than the TIS7/PC4 protein. Using antisera prepared against recombinant TIS21 and TIS7 proteins, we find that the TIS21/PC3 protein is, indeed, synthesized more rapidly than the TIS7/PC4 protein following stimulation in both 3T3 and PC12 cells. In addition, “pulse-chase” experiments demonstrate that the TIS21/PC3 protein is degraded much more rapidly than the TIS7/PC4 protein. The sequences of the predicted PC3 and PC4 proteins have lead to the speculation that these two proteins may both be secreted from cells following stimulation. The PC4 protein is reported to have some sequence similarity to interferons. The TIS21/PC3 protein contains a presumptive leader sequence. Using our antisera to the recombinant proteins, however, we cannot detect secretion of radiolabelled TIS7/PC4 or TIS21/PC3 protein. Immunohistochemical and subcellular fractionation experiments suggest that the TIS7 protein is a membrane associated, non-nuclear intracellular protein. The TIS21 protein, in contrast, is' a non-nuclear, soluble intracellular protein. © 1994 Wiley-Liss, Inc. 相似文献
6.
7.
Gopinath Chattopadhyay Shahbaz Ahmed Nonavinakere Seetharam Srilatha Aparna Asok Raghavan Varadarajan 《Protein science : a publication of the Protein Society》2023,32(1):e4514
Regulation of biological processes by proteins often involves the formation of transient, multimeric complexes whose characterization is mechanistically important but challenging. The bacterial toxin CcdB binds and poisons DNA Gyrase. The corresponding antitoxin CcdA extracts CcdB from its complex with Gyrase through the formation of a transient ternary complex, thus rejuvenating Gyrase. We describe a high throughput methodology called Ter-Seq to stabilize probable ternary complexes and measure associated kinetics using the CcdA-CcdB-GyrA14 ternary complex as a model system. The method involves screening a yeast surface display (YSD) saturation mutagenesis library of one partner (CcdB) for mutants that show enhanced ternary complex formation. We also isolated CcdB mutants that were either resistant or sensitive to rejuvenation, and used surface plasmon resonance (SPR) with purified proteins to validate the kinetics measured using the surface display. Positions, where CcdB mutations lead to slower rejuvenation rates, are largely involved in CcdA-binding, though there were several notable exceptions suggesting allostery. Mutations at these positions reduce the affinity towards CcdA, thereby slowing down the rejuvenation process. Mutations at GyrA14-interacting positions significantly enhanced rejuvenation rates, either due to reduced affinity or complete loss of CcdB binding to GyrA14. We examined the effect of different parameters (CcdA affinity, GyrA14 affinity, surface accessibilities, evolutionary conservation) on the rate of rejuvenation. Finally, we further validated the Ter-Seq results by monitoring the kinetics of ternary complex formation for individual CcdB mutants in solution by fluorescence resonance energy transfer (FRET) studies. 相似文献
8.
V. Raghavan 《American journal of botany》1988,75(2):183-196
Investigations of the growth of anthers and ontogeny of pollen grains of Oryza sativa (rice) IR-30 were undertaken for the purpose of 1) providing a set of growth measurements and 2) describing stable cytological features of anther and pollen development. Correlations exist between elongation of the floret and growth parameters of the anther such as its length, width, fresh and dry weights and cytological stage of pollen development. In the early ontogeny of the anther, hypodermal archesporial initials divide periclinally to form primary parietal cells and primary sporogenous cells. Each of the latter divides twice mitotically to generate four microspore mother cells, which undergo meiosis. The anther wall is formed by anticlinal and periclinal divisions of the primary parietal cells as well as of cells surrounding the primary sporogenous cells. Subsequent cytological features in the development of anther and pollen grains of rice have much in common with anther and pollen developmental biology of other members of Gramineae. 相似文献
9.
M. Raghavan J. A. Lebrón J. L. Johnson P. J. Bjorkman 《Protein science : a publication of the Protein Society》1996,5(10):2080-2088
Recognition of self peptides bound to the class I major histocompatibility complex molecule HLA-B27 is thought to trigger proliferation of autoreactive T cells and result in autoimmune arthritic diseases. Previous work from other laboratories established that a predominant feature of endogenous peptides eluted from purified B27 is an arginine at position 2. We studied the binding of peptides containing both natural and unnatural amino acids by the subtype HLA-B*2702, with the goal of gaining insight into peptide binding by this B27 subtype that is associated with susceptibility to arthritic disease. A soluble from of B*2702 was depleted of endogenous peptides. We tested the binding of peptides substituted with cysteine, homocysteine, or an alpha-amino-epsilon-mercapto hexanoic acid side chain (Amh) instead of the naturally occurring arginine at position 2, to determine whether the peptide sulfhydryl residue could be covalently linked to cysteine 67 in the B*2702 binding cleft. Although none of the altered peptide sequences bound covalently to B*2702, the affinities of the homocysteine- and Amh-substituted peptides were close to that of the native peptide sequence. Substitutions at position 2 with other side chains, such as glutamine and methionine, also resulted in peptides that bound with only slightly reduced affinity. These results demonstrate that peptide side chains other than arginine at position 2 can be accomodated within the B*2702 peptide binding site with only minor reductions in affinity. This extended repertoire of permissible B27-binding peptides should be taken into account for a consideration of disease-associated peptide sequences. 相似文献
10.
Altered physicochemical characteristics of polyethylene glycol linked beet stem oxalate oxidase 总被引:1,自引:0,他引:1
Oxalate oxidase (EC 1.2.3.4), obtained from the beet stem, was covalently linked to polyethylene glycol (PEG). Compared with native enzyme, the modified oxalate oxidase exhibited decreased electrophoretic mobility, increased storage stability, higher thermal stability, and resistance to heavy metal inactivation and proteolytic digestion. The chemical modification of oxalate oxidase with PEG also brought about a marked shift in its optimal pH, from pH 4.5 to 6.5, without altering its Michaelis constant (K(m)) significantly. These acquired properties of the immobilized oxalate oxidase render it suitable for possible applications in clinical, nutritional, and medical fields. (c) 1995 John Wiley & Sons, Inc. 相似文献