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61.
AHMED S.I.-U. 《科学通报(英文版)》2009,54(10):1648-1654
Some insects and animals, such as bugs, grasshoppers and tree frogs, realize their efficient adhesion mechanism to glass surface,
wall and ceiling by injecting a wetting liquid thin film into the pad-substrate contact area. Their ability to control adhesion
(attaching or detaching from a surface) is in many cases connected to the contact geometry and surface patterns of their attachment
pads. This paper focuses on the dependence of the capillary adhesion (wet adhesion) on the micro patterns of the bio-adhesive
pads. The objective is to reveal the possible mechanism for a bio-adhesive pad to control capillary force through adjusting
its micro-scale surface pattern and topography. A capillary adhesion force model is built up taking account of the combined
role of micro-dimple geometry as well as the wetting behavior of the confined liquid thin film. Calculated results of the
apparent contact angle on the regularly micro-dimpled surfaces are compared with and in good agreement with the experimental
measurements. Simulation of the capillary adhesion force reveals that it is controllable in a large magnitude by adjusting
a dimensionless surface pattern parameter k defined as a/(a+b), where a is the diameter of micro dimple, and (a+b) is the side length of one pattern cell. When adjusting the parameter k more than 0.75, the capillary adhesion force could
be switchable from attractive to repulsive. This effect of micro patterns on the interfacial capillary force is proved to
be dominant when the pad-substrate clearance decreases to the nano/micrometer scale. These results indicate that a controllable
and switchable capillary adhesive mechanism might be utilized by a living insect or animal to realize its stable adhesion
and quick releasing movement through adjusting the micro-pattern topography of its bio-adhesive pad.
Supported by the National Natural Science Foundation of China (Grant Nos. 50575123, 50730007), PPP Project from CSC and DAAD,
and German Research Foundation (DFG) (Grant No. SFB622) (Y.H. Liu and S.I.-U. Ahmed) 相似文献
62.
The present paper reports on a systematic study of the influence of Zn alloying on the
structural and optical properties of Cd1 xZnxS thin films. X-ray diffraction study for structural
analysis reveals that the two binary compounds have been completely transformed into ternary
compound with hexagonal (wurtzite) structure with preferred orientation along c-direction with
(002) planes. The optical properties such as optical constants and band gap energy of the films were
examined by using spectroscopic ellipsometer and Photospectrometery. It was found that the
optical constants (n and k) decrease with the addition of Zn content in the alloy. It was also
confirmed that the band gap increases with increasing Zn amount in the alloy and is attributed to
quantum size effect in the grain size. Raman spectroscopy analysis shows one dominant phonon
band at 326 cm 1, the so-called longitudinal optical (LO) mode for all the alloy composition (x).
The appearance of a single phonon band in the Raman spectra established the formation of single
phase hexagonal structured Cd1 xZnxS thin film. The LO band is asymmetrically broaden and high
frequency shifted due to potential fluctuation caused by the dopant material. The AFM results
showed that the surface roughness was decreased with increasing Zn content. 相似文献
63.
Indomethacin and inhibition of protein kinase reactions 总被引:3,自引:0,他引:3
Indomethacin, an inhibitor of prostaglandin biosynthesis, is useful in studies aimed at understanding the metabolism and physiological function of prostaglandins. A recent report showing that indomethacin at 10(-7) M potently inhibits the cyclic AMP-dependent protein kinases (cAMP-PrK) from ileal mucosa in the presence or absence of cyclic AMP, suggests how indomethacin may antagonize prostaglandin action on ileal mucosa. It also suggests that indomethacin might be useful in studying the properties and functions of protein kinase reactions. Inhibitors of prostaglandin biosynthesis, such as sodium salicylate and acetylsalicylate, at concentrations near 10(-2) M, have been shown to inhibit bovine diaphragm protein kinase only in the presence of cAMP, while stimulating it in the absence of cAMP. We report here that complete inhibition of cAMP-PrKs by indomethacin requires a concentration of 10(-3) M and is not tissue-specific, and that the effect of indomethacin is concentration dependent above 2 x 10(-4) M for the cAMP-dependent, and above 10(-3) M for cAMP-independent PrKs. These results contrast previous ones. 相似文献
64.
Sub-zero temperatures can be used to trap intermediates in enzyme-catalysed reactions using suitable cryosolvents. The feasibility of obtaining such intermediates in the crystalline state for X-ray diffraction studies has been demonstrated with several proteases, using specific substrates and optimal pH. 相似文献
65.
Dominant and recessive deafness caused by mutations of a novel gene, TMC1, required for cochlear hair-cell function 总被引:15,自引:0,他引:15
Kurima K Peters LM Yang Y Riazuddin S Ahmed ZM Naz S Arnaud D Drury S Mo J Makishima T Ghosh M Menon PS Deshmukh D Oddoux C Ostrer H Khan S Riazuddin S Deininger PL Hampton LL Sullivan SL Battey JF Keats BJ Wilcox ER Friedman TB Griffith AJ 《Nature genetics》2002,30(3):277-284
Positional cloning of hereditary deafness genes is a direct approach to identify molecules and mechanisms underlying auditory function. Here we report a locus for dominant deafness, DFNA36, which maps to human chromosome 9q13-21 in a region overlapping the DFNB7/B11 locus for recessive deafness. We identified eight mutations in a new gene, transmembrane cochlear-expressed gene 1 (TMC1), in a DFNA36 family and eleven DFNB7/B11 families. We detected a 1.6-kb genomic deletion encompassing exon 14 of Tmc1 in the recessive deafness (dn) mouse mutant, which lacks auditory responses and has hair-cell degeneration. TMC1 and TMC2 on chromosome 20p13 are members of a gene family predicted to encode transmembrane proteins. Tmc1 mRNA is expressed in hair cells of the postnatal mouse cochlea and vestibular end organs and is required for normal function of cochlear hair cells. 相似文献
66.
M. J. Wilson Dr. J. M. McMillin U. S. Seal K. Ahmed 《Cellular and molecular life sciences : CMLS》1976,32(7):944-945
Summary Serum testosterone concentrations were measured in adult male Sprague-Dawley rats. A significant circadian testosterone rhythm (p<0.01) was found with peak values at 10.00 and 13.00 h.Supported in part by NIH, NCI Grant No. CA 15062 and NIH, NIAMDD Grant No. 5 RO1 AM11376.The authors would like to acknowledge the excellent technical assistance of Ms.Kris Strom. 相似文献
67.
Summary Pea embryos grown in the presence of 2.5 mM hydroxyurea from the beginning of imbibition showed a mitotic peak the height of which was considerably less than that of the control, material. Soon after the mitotic peak, there was a complete cessation of mitosis in the treated material. The extent of suppression of mitosis during the first post-dormancy cell cycle caused by hydroxyurea has been used to obtain an estimate of the relative proportion of 2C and 4C cells in the embryo. 相似文献
68.
Genome-wide association study identifies a common variant associated with risk of endometrial cancer
Spurdle AB Thompson DJ Ahmed S Ferguson K Healey CS O'Mara T Walker LC Montgomery SB Dermitzakis ET;Australian National Endometrial Cancer Study Group Fahey P Montgomery GW Webb PM Fasching PA Beckmann MW Ekici AB Hein A Lambrechts D Coenegrachts L Vergote I Amant F Salvesen HB Trovik J Njolstad TS Helland H Scott RJ Ashton K Proietto T Otton G;National Study of Endometrial Cancer Genetics Group Tomlinson I Gorman M Howarth K Hodgson S Garcia-Closas M Wentzensen N Yang H Chanock S Hall P 《Nature genetics》2011,43(5):451-454
Endometrial cancer is the most common malignancy of the female genital tract in developed countries. To identify genetic variants associated with endometrial cancer risk, we performed a genome-wide association study involving 1,265 individuals with endometrial cancer (cases) from Australia and the UK and 5,190 controls from the Wellcome Trust Case Control Consortium. We compared genotype frequencies in cases and controls for 519,655 SNPs. Forty seven SNPs that showed evidence of association with endometrial cancer in stage 1 were genotyped in 3,957 additional cases and 6,886 controls. We identified an endometrial cancer susceptibility locus close to HNF1B at 17q12 (rs4430796, P = 7.1 × 10(-10)) that is also associated with risk of prostate cancer and is inversely associated with risk of type 2 diabetes. 相似文献
69.
Neveen S. Gadallah Ahmed M. Soliman Usama M. Abu El-Ghiet Tarek Y. Elsheikh Hathal M. Al Dhafer 《Journal of Natural History》2018,52(31-32):2071-2096
The family Leucospidae (Hymenoptera: Chalcidoidea) from Saudi Arabia is reviewed. Specimens were mainly collected from the south-western region of the country – Raydah (Abha, Asir), Sajid (Farasan Islands, Jazan) and Wadi Tourabah (Mandaq, Al Baha); and from Egypt – Wadi Khoshb (Sinai Peninsula), as well as a specimen (Leucospis elegans Klug) deposited in the Efflatoun Bey collection, Cairo University, Egypt. The genus Micrapion Kriechbaumer is here recorded for the first time from the fauna of the Arabian Peninsula, with a single species, M. clavaforme. Leucospis arabica Gadallah and Soliman sp. nov. (dorsigera group) is described. Leucospis africana (elegans group) is also newly recorded from the Saudi Arabian fauna, in addition to L. elegans which has been previously recorded. An illustrated key and a list of all leucospid species recorded and expected to occur in Saudi Arabia are provided.
www.zoobank.org/lsid:Zoobank.org:pub:40BEF37F-0D92-4AEF-9990-30C1CFC3A7A7 相似文献
70.
Ghoussaini M Fletcher O Michailidou K Turnbull C Schmidt MK Dicks E Dennis J Wang Q Humphreys MK Luccarini C Baynes C Conroy D Maranian M Ahmed S Driver K Johnson N Orr N dos Santos Silva I Waisfisz Q Meijers-Heijboer H Uitterlinden AG Rivadeneira F;Netherlands Collaborative Group on Hereditary Breast Ovarian Cancer 《Nature genetics》2012,44(3):312-318
Breast cancer is the most common cancer among women. To date, 22 common breast cancer susceptibility loci have been identified accounting for ~8% of the heritability of the disease. We attempted to replicate 72 promising associations from two independent genome-wide association studies (GWAS) in ~70,000 cases and ~68,000 controls from 41 case-control studies and 9 breast cancer GWAS. We identified three new breast cancer risk loci at 12p11 (rs10771399; P = 2.7 × 10(-35)), 12q24 (rs1292011; P = 4.3 × 10(-19)) and 21q21 (rs2823093; P = 1.1 × 10(-12)). rs10771399 was associated with similar relative risks for both estrogen receptor (ER)-negative and ER-positive breast cancer, whereas the other two loci were associated only with ER-positive disease. Two of the loci lie in regions that contain strong plausible candidate genes: PTHLH (12p11) has a crucial role in mammary gland development and the establishment of bone metastasis in breast cancer, and NRIP1 (21q21) encodes an ER cofactor and has a role in the regulation of breast cancer cell growth. 相似文献