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81.
82.
Prem P. Jauhar 《Genetica》1968,39(1):360-370
Meiosis in the interspecific hybrid betweenPennisetum typhoides (2n=14; genomeAA) andP. purpureum (2n=28; genomesA′A′BB) has been studied with particular reference to allosyndetic and autosyndetic pairing of chromosomes. Although up to nine
bivalents occurred in the hybrid, never more than five were observed to be (heteromorphic)AA′ bivalents (range 1–5). It has been concluded thatA andA′ genomes are onlypartially homologous. It has further been inferred that the two genomes are evolutionarily related and could have arisen from a common progenitor
withx=5 chromosomes or from related species withx=5 chromosomes.
Autosyndetic pairing of chromosomes within thetyphoides complement (A genome) and within theA′ genome ofpurpureum have been reported here for the first time. Intra-haploid pairing to a probable maximum of two bivalents within each of the
three genomes of the hybrid, viz.,A, A′ andB, further suggestsx=5 as the phyletically basic number in the genusPennisetum. It has been inferred thatx=7 is a secondarily basic number, having been derived fromx=5. The occurrence of a species withn=5 inPennisetum, viz.,P. ramosum, substantiates this view. Further support in favour of this conclusion comes from the secondary association of bivalents
in dipoidP. typhoides. Thus, the apparently diploid species,Pennisetum typhoides with2n=14 chromosomes is considered to be a “secondary diploid” having a secondarily balanced number ofx=7.
On the basis of the results obtained by the author is conjunction with the available evidence from the literature, it is suggested
thatx=5 may be the original basic number for the entire grass family and seven, the most preponderant number in it, and other higher
numbers derived from it subsequently during the course of evolution. 相似文献
83.
Wan-Hsing Cheng Prem S. Chourey 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1999,98(3-4):485-495
Cell wall-bound invertase (CWI) is spatially and temporally the first enzyme which metabolizes the incoming sucrose in developing
seed of maize (Zea mays). Our previous studies have shown that the cell wall-bound invertase-2 (INCW2) isozyme encoded by the wild-type gene of the
Miniature1 (Mn1) seed locus plays a critical role in seed development. Null mutations of the gene, such as the mn1 seed mutant which lacks invertase activity, are associated with a loss of ∼70–80% of the normal seed weight. We show here
that under in vitro kernel culture conditions the hexose-based medium was similar to the sucrose-based medium in promoting
the normal development of kernels of the Mn1, but not of the mutant mn1, genotype. Anatomical, biochemical, and immunohistological data showed that the mn1 kernels retain their mutant phenotype regardless of the presence of sucrose or hexoses in the culture media. The most drastic
changes in the mn1 seed mutant were associated with a significant reduction in the size of the endosperm, but not in the pattern or the level
of starch localization. Because Mn1 expression was temporally coincident with the endosperm cell divisions, INCW2 must play a critical role in providing hexose
sugars for mitotic division, and only a minor role in generating carbon skeletal substrates for starch biosynthesis in the
early stages of endosperm development. Furthermore, a lack of the wild-type seed phenotype of the mn1 mutant in hexose media suggests that a metabolic release of hexoses catalyzed by INCW2, rather than an exogenous source,
is critical for both generating appropriate sugar-sensing signals for gene expression and for normal endosperm development.
Received: 8 April 1998 / Accepted: 14 August 1998 相似文献
84.
Gayoor Ali A. Arif Ibrahim Prem Shankar Srivastava Muhammad Iqbal 《Journal of Plant Biology》1999,42(3):222-225
Various concentrations of salt (NaCI) were shown to have an influence on the differentiation of tissues in the root and stem
ofBacopa monniera (L) Wettst. Higher concentrations induced drastic changes in roots grown on salt-supplemented media; epidermal and cortical
cells experienced changes in shape, size, and orientation and/or were got disintegrated. A low concentration of salt induced
a profuse development of root hairs which gradually disappeared at higher concentrations. Air spaces in the stem cortex were
enlarged and xylem cell walls in the vascular ring were thickened. 相似文献
85.
Sharad Porwal Suman Gupta Prem M.S. Chauhan 《Bioorganic & medicinal chemistry letters》2017,27(20):4643-4646
In this communication we report a serendipitously discovered hybrid molecule 1, combining fragment of 3 (an in vivo active antileishmanial molecule) with H2S donor moiety (known for bimodal behavior of cytoprotection and apoptosis), as antileishmanial agent. Compound 1 suppresses 99.82% parasitemia of L. donovani infected macrophages at 12.5 μg/ml without even deforming them (CC50 > 100 μg/ml). This compound appears cytotoxic for intracellular amastigotes while cytoprotective to host macrophages. The concept can be utilized to develop high therapeutic index NCE (New Chemical Entities) for other macrophage mediated diseases like tuberculosis and cancer. 相似文献
86.
Prashant Digpal S. Gour Prem P. Dubey Anubhav Jain Subhash C. Gupta Balwinder K. Joshi Dinesh Kumar 《Journal of applied genetics》2008,49(4):379-381
Sex determination in domestic animals is of potential value to livestock breeding programs. The aim of this study was to develop a simple and accurate PCR-based sex determination protocol, which can be applicable to 6 major domesticated species of the family Bovidae,viz. Bos frontalis, B. grunniens, B. indicus, Bubalus bubalis, Capra hircus, andOvis aries. In silico analysis was done to identify conserved DNA sequence in the HMG box region of the sex-determining region of the Y-chromosome (SRY gene) across the bovids. Duplex PCR assay, including theSRY gene and theGAPDH housekeeping gene, was optimized by using genomic DNA extracted from blood samples of known sex. It was possible to identify the sex of animals by amplifying both gender-specific (SRY) and autosomal (GAPDH) genes simultaneously in the duplex reaction, with the male yielding two bands and the female one band. The protocol was subjected to a blind test that showed a 100 percent specificity and accuracy, thus it can be used in sex determination in livestock breeding programs. 相似文献
87.
88.
Atrial natriuretic factor receptor guanylate cyclase signaling: new ATP-regulated transduction motif
Teresa Duda Shashank Bharill Ireneusz Wojtas Prem Yadav Ignacy Gryczynski Zygmunt Gryczynski Rameshwar K. Sharma 《Molecular and cellular biochemistry》2009,324(1-2):39-53
ANF-RGC membrane guanylate cyclase is the receptor for the hypotensive peptide hormones, atrial natriuretic factor (ANF) and type B natriuretic peptide (BNP). It is a single transmembrane spanning protein. Binding the hormone to the extracellular domain activates its intracellular catalytic domain. This results in accelerated production of cyclic GMP, a second messenger in controlling blood pressure, cardiac vasculature, and fluid secretion. ATP is the obligatory transducer of the ANF signal. It works through its ATP regulated module, ARM, which is juxtaposed to the C-terminal side of the transmembrane domain. Upon interaction, ATP induces a cascade of temporal and spatial changes in the ARM, which, finally, result in activation of the catalytic module. Although the exact nature and the details of these changes are not known, some of these have been stereographed in the simulated three-dimensional model of the ARM and validated biochemically. Through comprehensive techniques of steady state, time-resolved tryptophan fluorescence and Forster Resonance Energy Transfer (FRET), site-directed and deletion-mutagenesis, and reconstitution, the present study validates and explains the mechanism of the model-based predicted transduction role of the ARM’s structural motif, 669WTAPELL675. This motif is critical in the ATP-dependent ANF signaling. Molecular modeling shows that ATP binding exposes the 669WTAPELL675 motif, the exposure, in turn, facilitates its interaction and activation of the catalytic module. These principles of the model have been experimentally validated. This knowledge brings us a step closer to our understanding of the mechanism by which the ATP-dependent spatial changes within the ARM cause ANF signaling of ANF-RGC. 相似文献
89.
90.
Nagendra Singh Ramasamy Prem Kumar Sanjit Kumar Sujata Sharma Rafia Mir Punit Kaur Alagiri Srinivasan Tej P. Singh 《Journal of molecular recognition : JMR》2009,22(6):437-445
A novel ligand‐binding site with functional implications has been identified in phospholipase A2 (PLA2). The binding of non‐steroidal anti‐inflammatory agent indomethacin at this site blocks both catalytic and anti‐coagulant actions of PLA2. A group IIA PLA2 has been isolated from Daboia russelli pulchella (Russell's viper) which is enzymatically active as well as induces a strong anti‐coagulant action. The binding studies have shown that indomethacin reduces the effects of both anti‐coagulant and pro‐inflammatory actions of PLA2. A group IIA PLA2 was co‐crystallized with indomethacin and the structure of the complex has been determined at 1.4 Å resolution. The structure determination has revealed the presence of an indomethacin molecule in the structure of PLA2 at a site which is distinct from the conventional substrate‐binding site. One of the carboxylic group oxygen atoms of indomethacin interacts with Asp 49 and His 48 through the catalytically important water molecule OW 18 while the second carboxylic oxygen atom forms an ionic interaction with the side chain of Lys 69. It is well known that the residues, His 48 and Asp 49 are essential for catalysis while Lys 69 is a part of the anti‐coagulant loop (residues, 54–77). Indomethacin binds in such a manner that it blocks the access to both, it works as a dual inhibitor for catalytic and anti‐coagulant actions of PLA2. This new binding site in PLA2 has been observed for the first time and indomethacin is the first compound that has been shown to bind at this novel site resulting in the prevention of anti‐coagulation and inflammation. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献