全文获取类型
收费全文 | 370篇 |
免费 | 18篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 115篇 |
金属工艺 | 6篇 |
机械仪表 | 8篇 |
建筑科学 | 9篇 |
矿业工程 | 1篇 |
能源动力 | 10篇 |
轻工业 | 33篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 24篇 |
一般工业技术 | 57篇 |
冶金工业 | 80篇 |
原子能技术 | 4篇 |
自动化技术 | 36篇 |
出版年
2023年 | 2篇 |
2022年 | 4篇 |
2021年 | 11篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 6篇 |
2017年 | 6篇 |
2016年 | 12篇 |
2015年 | 11篇 |
2014年 | 9篇 |
2013年 | 16篇 |
2012年 | 10篇 |
2011年 | 21篇 |
2010年 | 23篇 |
2009年 | 15篇 |
2008年 | 12篇 |
2007年 | 9篇 |
2006年 | 6篇 |
2005年 | 15篇 |
2004年 | 9篇 |
2003年 | 3篇 |
2002年 | 11篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 8篇 |
1998年 | 22篇 |
1997年 | 19篇 |
1996年 | 12篇 |
1995年 | 4篇 |
1994年 | 11篇 |
1993年 | 7篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 9篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 7篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1973年 | 3篇 |
1972年 | 4篇 |
1969年 | 2篇 |
排序方式: 共有388条查询结果,搜索用时 31 毫秒
31.
Ivan Rehor Jitka Slegerova Jan Kucka Vladimir Proks Vladimira Petrakova Marie‐Pierre Adam François Treussart Stuart Turner Sara Bals Pavel Sacha Miroslav Ledvina Amy M. Wen Nicole F. Steinmetz Petr Cigler 《Small (Weinheim an der Bergstrasse, Germany)》2014,10(6):1106-1115
High pressure high temperature (HPHT) nanodiamonds (NDs) represent extremely promising materials for construction of fluorescent nanoprobes and nanosensors. However, some properties of bare NDs limit their direct use in these applications: they precipitate in biological solutions, only a limited set of bio‐orthogonal conjugation techniques is available and the accessible material is greatly polydisperse in shape. In this work, we encapsulate bright 30‐nm fluorescent nanodiamonds (FNDs) in 10–20‐nm thick translucent (i.e., not altering FND fluorescence) silica shells, yielding monodisperse near‐spherical particles of mean diameter 66 nm. High yield modification of the shells with PEG chains stabilizes the particles in ionic solutions, making them applicable in biological environments. We further modify the opposite ends of PEG chains with fluorescent dyes or vectoring peptide using click chemistry. High conversion of this bio‐orthogonal coupling yielded circa 2000 dye or peptide molecules on a single FND. We demonstrate the superior properties of these particles by in vitro interaction with human prostate cancer cells: while bare nanodiamonds strongly aggregate in the buffer and adsorb onto the cell membrane, the shell encapsulated NDs do not adsorb nonspecifically and they penetrate inside the cells. 相似文献
32.
Laurène Legrand Sylvain Patinet Jean-Baptiste Leblond Joël Frelat Véronique Lazarus Damien Vandembroucq 《International Journal of Fracture》2011,170(1):67-82
Several groups have studied experimentally the deformation of the front of mode I cracks propagating quasistatically along
the interface between bonded plates. The theoretical interpretation of such experiments has always been based up to now on
a formula of Rice (ASME J Appl Mech 52:571–579, 1985); this formula provides the first-order variation of the local mode I stress intensity factor resulting from some small,
but otherwise arbitrary coplanar perturbation of the front of a semi-infinite crack in an infinite body. To be applicable
to bonded plates, this formula requires that the characteristic distance of variation of this perturbation in the direction
of the crack front be small compared to all other characteristic dimensions of the problem, and first of all the thickness
of the plates. This condition is unfortunately frequently violated in practice. The purpose of this paper is therefore to
provide a more exact formula for the variation of the local stress intensity factor, for the specific cracked geometry and
boundary conditions used in experiments; this should allow for more accurate theoretical interpretations. This is done in
two steps. The first one consists in adapting Rice’s (ASME J Appl Mech 52:571–579, 1985) treatment, applicable to the extreme case of plates of infinite thickness, to the other extreme one of plates of infinitesimal
thickness, using the standard Love-Kirchhoff plate theory. An interesting outcome of the analysis is that the distance from
the crack front to the boundary of the plate acts as a “cutoff length”, in the sense that when the distance between two points
on the crack front gets larger than it, the influence of the crack advance at the first point upon the stress intensity factor
at the second diminishes quickly; the plate thickness, however, plays no similar role. The second step consists in supplementing
the theoretical expressions applicable to extreme values of the plate thickness with finite element computations providing
results for intermediate values. These computations lead to the definition of a simple, approximate but accurate “interpolation
formula” for the variation of the local stress intensity factor, applicable to plates of arbitrary thickness. 相似文献
33.
C Belloc H Lu C Soria R Fridman Y Legrand S Menashi 《Canadian Metallurgical Quarterly》1995,60(3):413-417
Interaction of tumor cells with platelets facilitates metastasis of tumor cells. It has been proposed that platelets protect tumor cells against the host's immune defense and enhance tumor-cell extravasation. In the present work we show that platelets increase the invasiveness of 3 mammalian cell lines (MCF-7, ZR-51 and MDA-MB231) through extracellular matrix, and propose this as an additional mechanism by which platelets facilitate metastasis. Since gelatinase and urokinase have both been implicated in degradation of the extracellular matrix and cell migration, and therefore in tumor invasion, we have also analyzed whether the interaction of platelets with tumor cells can modify the secretion of these proteases by tumor cells. MDA-MB231, which was the most invasive cell line among the 3 tested and was the most potent in inducing platelet aggregation, secreted the highest level of urokinase and was the only one in which gelatinase was detected. While platelets had no significant effect on the urokinase activity expressed by these cells, they induced in MDA-MB231 an important increase in the secretion of gelatinase, which can be reproduced by both platelet membrane and platelet releasate of activated platelets. This increase in gelatinase could be responsible, at least in part, for the increased invasiveness of these cells, since added TIMP-1 significantly reduced the number of cells which traversed matrigel. 相似文献
34.
R Hakenbeck A K?nig I Kern M van der Linden W Keck D Billot-Klein R Legrand B Schoot L Gutmann 《Canadian Metallurgical Quarterly》1998,180(7):1831-1840
Penicillin-resistant isolates of Streptococcus pneumoniae generally contain mosaic genes encoding the low-affinity penicillin-binding proteins (PBPs) PBP2x, PBP2b, and PBP1a. We now present evidence that PBP2a and PBP1b also appear to be low-affinity variants and are encoded by distinct alleles in beta-lactam-resistant transformants of S. pneumoniae obtained with chromosomal donor DNA from a Streptococcus mitis isolate. Different lineages of beta-lactam-resistant pneumococcal transformants were analyzed, and transformants with low-affinity variants of all high-molecular-mass PBPs, PBP2x, -2a, -2b, -1a, and -1b, were isolated. The MICs of benzyl-penicillin, oxacillin, and cefotaxime for these transformants were up to 40, 100, and 50 microg/ml, respectively, close to the MICs for the S. mitis donor strain. Recruitment of low-affinity PBPs was accompanied by a decrease in cross-linked muropeptides as revealed by high-performance liquid chromatography of muramidase-digested cell walls, but no qualitative changes in muropeptide chemistry were detected. The growth rates of all transformants were identical to that of the parental S. pneumoniae strain. The results stress the potential for the acquisition by S. pneumoniae of high-level beta-lactam resistance by interspecies gene transfer. 相似文献
35.
36.
37.
38.
39.
C Vénien-Bryan PF Lenne C Zakri A Renault A Brisson JF Legrand B Berge 《Canadian Metallurgical Quarterly》1998,74(5):2649-2657
We present here some sensitive optical and mechanical experiments for monitoring the process of formation and growth of two-dimensional (2D) crystals of proteins on a lipid monolayer at an air-water interface. The adsorption of proteins on the lipid monolayer was monitored by ellipsometry measurements. An instrument was developed to measure the shear elastic constant (in plane rigidity) of the monolayer. These experiments have been done using cholera toxin B subunit (CTB) and annexin V as model proteins interacting with a monosialoganglioside (GM1) and dioleoylphosphatidylserine (DOPS), respectively. Electron microscopy observations of the protein-lipid layer transferred to grids were systematically used as a control. We found a good correlation between the measured in-plane rigidity of the monolayer and the presence of large crystalline domains observed by electron microscopy grids. Our interpretation of these data is that the crystallization process of proteins on a lipid monolayer passes through at least three successive stages: 1) molecular recognition between protein and lipid-ligand, i.e., adsorption of the protein on the lipid layer; 2) nucleation and growth of crystalline patches whose percolation is detected by the appearance of a non-zero in-plane rigidity; and 3) annealing of the layer producing a slower increase of the lateral or in-plane rigidity. 相似文献
40.