全文获取类型
收费全文 | 1944篇 |
免费 | 10篇 |
专业分类
电工技术 | 7篇 |
化学工业 | 71篇 |
金属工艺 | 14篇 |
机械仪表 | 3篇 |
建筑科学 | 16篇 |
能源动力 | 20篇 |
轻工业 | 33篇 |
石油天然气 | 1篇 |
无线电 | 22篇 |
一般工业技术 | 55篇 |
冶金工业 | 1677篇 |
原子能技术 | 4篇 |
自动化技术 | 31篇 |
出版年
2022年 | 6篇 |
2021年 | 8篇 |
2020年 | 4篇 |
2019年 | 11篇 |
2018年 | 8篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2014年 | 6篇 |
2013年 | 20篇 |
2012年 | 19篇 |
2011年 | 15篇 |
2010年 | 4篇 |
2009年 | 7篇 |
2008年 | 20篇 |
2007年 | 7篇 |
2006年 | 10篇 |
2005年 | 19篇 |
2004年 | 3篇 |
2003年 | 14篇 |
2002年 | 6篇 |
2001年 | 7篇 |
2000年 | 10篇 |
1999年 | 55篇 |
1998年 | 576篇 |
1997年 | 300篇 |
1996年 | 187篇 |
1995年 | 105篇 |
1994年 | 89篇 |
1993年 | 125篇 |
1992年 | 18篇 |
1991年 | 20篇 |
1990年 | 20篇 |
1989年 | 20篇 |
1988年 | 20篇 |
1987年 | 14篇 |
1986年 | 13篇 |
1985年 | 16篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 9篇 |
1979年 | 3篇 |
1977年 | 37篇 |
1976年 | 59篇 |
1975年 | 4篇 |
1974年 | 3篇 |
1973年 | 5篇 |
1970年 | 3篇 |
1969年 | 2篇 |
排序方式: 共有1954条查询结果,搜索用时 15 毫秒
51.
WC Parris BW Johnson MK Croghan MR Moore A Khojasteh RF Reder RF Kaiko BJ Buckley 《Canadian Metallurgical Quarterly》1998,16(4):205-211
1. We have studied the effects of muscarinic cholinoceptor agonists and subtype-preferring antagonists on the isometric contraction of smooth muscle strips from dog prostate. 2. Acetylcholine and carbachol induced contraction of prostate strips from the peripheral zone, ('the capsule'). Bethanechol contracted the tissue but not at lower doses. McN-A-343 and oxotremorine-M showed the same effects. 3. Blocking alpha- and beta-adrenoceptors with phentolamine and propranolol, respectively, did not modify carbachol-induced contractions. 4. The nicotinic receptor blocker, hexamethonium (10(-6)-10(-4) M) did not affect the contractile response evoked by a single dose of carbachol (10(-5) M), whilst the muscarinic receptor antagonist, atropine (10(-11)-10(-9) M), inhibited it in a competitive manner. 5. The muscarinic M1 (pirenzepine), M2 [AF-DX 116, himbacine (M2/M4) and methoctramine], M3 (HHSID and f-F-HHSID), and putative M4 (tropicamide) antagonists reduced significantly the carbachol-induced contractions. The pIC50 values were: atropine (10.01) > himbacine (8.3) > methoctramine (7.85) > AF-DX 116 (7.60) > HHSID (7.21) > p-F-HHSID (7.10) > pirenzepine (7.30) > tropicamide (7.00). 6. The antagonist profile indicates that an predominant M2 receptor subtype could mediate the muscarinic contraction in the canine prostate. 相似文献
52.
53.
54.
Residual glutaraldehyde (GA) in collagenous cardiovascular tissue prostheses after multiple saline rinses remains in the prostheses and accounts for adsorption and conjugation of a variety of plasma proteins. This may account for later beneficial or adverse effects. Human serum albumin (SA), gamma globulin (GG), and fibrinogen (FB) were iodinated with 125I using the iodogen-transfer technique. Bovine pericardium (PC) was fixed with 0.5% GA for 24 hr and rinsed to remove excess GA. Fresh and GA-fixed PC (FRPC, GAPC: 1 x 1 cm2), in triplicate, were incubated with 0.5-1.0 microCi of tracers in human, porcine, or bovine blood (2 ml) for a period of 0.5, 1, 2, and 3 hr and washed (5x) with saline. Maximum adsorbed proteins per unit weight of collagen (pmol/mg of PC, mean +/- SD) at 3 hr on FRPC and GAPC were quantified with a gamma counter. Fixed PC absorbed significantly more plasma proteins from blood than fresh PC. These conjugated plasma proteins are tightly bound to fixed PC. The adsorbed and conjugated plasma proteins for GAPC and FRPC have the same sequence: SA > GG > FB vs SA > GG > FB. Protein conjugation may affect the remodeling of collagenous cardiovascular tissue prostheses post implantation. 相似文献
55.
We identified a 4.7kb cryptic plasmid in all ctxAB+ Vibrio cholerae strains we tested. An isolate of the V. cholerae classical biotype strain 0395 that harbours the cryptic plasmid at high copy number was found. Hybridization analysis demonstrated that sequences highly related or identical to this plasmid exist in all toxigenic strains of V. cholerae but were notably absent in all non-toxigenic environmental isolates that lacked the genes for toxin-co-regulated pili and the filamentous CTX prophage. Accordingly, we have named the cryptic plasmid pTLC for toxin-linked cryptic. The complete nucleotide sequence of pTLC from the high-copy-number isolate was determined. The largest open reading frame in the plasmid is predicted to encode a protein similar to the replication initiation protein (pII) of Escherichia coli F-specific filamentous phages. The nucleotide sequence of pTLC also facilitated the structural characterization of the DNA homologous to pTLC in other strains of V. cholerae. pTLC-related DNA exists in these strains as both low-copy-number, covalently closed circular DNA and tandemly duplicated, chromosomally integrated DNA. Remarkably, the chromosomally integrated form of pTLC is adjacent to the CTX prophage. The strain distribution, chromosomal location and DNA sequence of pTLC suggests that it may be a genetic element that plays some role in the biology of CTXphi, perhaps facilitating either its acquisition or its replication. 相似文献
56.
57.
58.
Contamination of enteral diets may play an essential role in formula tolerance and safety for patients. Contaminated enteral formula commonly support microbiological growth. Commercially sterile liquid formulas received from the manufacturer are required by the Food & Drug Administration (FDA) to be shelf-stable and free from enteric pathogens. This study examined the use of large volume, closed system containers in a typical nursing home. Large volume (1500 mL) containers with unique pierceable caps and piercing spikes were studied to determine their ability to reduce the incidence of microbiological contamination due to their design and ability to decrease handling requirements. This study took place in a room of a typical nursing home. In this clinical setting, 211 containers and administration spike sets were evaluated following a 36-h hangtime. Contamination was virtually nondetectable. Nursing staff in a clinical facility can effectively utilize a large volume, prefilled, ready-to-use feeding system to achieve delivery of noncontaminated product for up to 36 h hangtime. 相似文献
59.
Declan C. Nolan Chris M. Tierney Cecil G. Armstrong Trevor T. Robinson Jonathan E. Makem 《Engineering with Computers》2014,30(4):689-701
The creation of idealised, dimensionally reduced meshes for preliminary design and optimisation remains a time-consuming, manual task. A dimensionally reduced model is ideal for assessing design changes through modification of element properties without the need to create a new geometry or mesh. In this paper, a novel approach for automating the creation of mixed dimensional meshes is presented. The input to the process is a solid model which has been decomposed into a non-manifold assembly of smaller volumes with different meshing significance. Associativity between the original solid model and the dimensionally reduced equivalent is maintained. The approach is validated by means of a free-free modal analysis on an output mesh of a gas turbine engine component of industrial complexity. Extensions and enhancements to this work are also discussed. 相似文献
60.
Mamballykalathil N. Menon Ho T. Fang David C. Wu Michael G. Jenkins Mattison K. Ferber Karren L. More Camden R. Hubbard Theodore A. Nolan 《Journal of the American Ceramic Society》1994,77(5):1217-1227
Cylindrical buttuohead specimens of an advanced silicon nitride were tested in uniaxial tension at temperatures between 1422 and 1673 K. In the range 1477 to 1673 K, creep deformation was reliably measured using high-temperature contact probe extensometry. Extensive scanning and transmission electron microscopy has revealed the formation of lenticular cavities at two-grain junctions at all temperatures (1422–1673 K) and extensive triple-junction cavitation occurring at the higher temperatures (1644–1673 K). Cavitation is believed to be part of the net creep process. The stress rupture data show stratification of the Monkman–Grant lines with respect to temperature. Failure strain increased with increase in rupture time or temperature, or decrease in stress. Fractography showed that final failure occurred by subcritical crack growth in all specimens. 相似文献