全文获取类型
收费全文 | 198篇 |
免费 | 2篇 |
专业分类
化学工业 | 4篇 |
轻工业 | 6篇 |
石油天然气 | 2篇 |
一般工业技术 | 2篇 |
冶金工业 | 186篇 |
出版年
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2013年 | 1篇 |
2011年 | 1篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2007年 | 1篇 |
2004年 | 2篇 |
1999年 | 3篇 |
1998年 | 48篇 |
1997年 | 23篇 |
1996年 | 28篇 |
1995年 | 13篇 |
1994年 | 9篇 |
1993年 | 16篇 |
1992年 | 3篇 |
1991年 | 4篇 |
1990年 | 6篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1980年 | 3篇 |
1977年 | 5篇 |
1976年 | 12篇 |
排序方式: 共有200条查询结果,搜索用时 24 毫秒
1.
2.
3.
A study was carried out to determine the prevalence of cervical intra-epithelial neoplasia (CIN) among women referred to Harare Hospital Colposcopy Clinic with a history of an abnormal smear. During the period, 132 patients were seen and 79 (60 pc) had colposcopic findings suggestive of CIN and 17 (13 pc) had inflammatory changes and 36 (27 pc) had normal findings. Electrocautery was used to treat low grade CIN lesions, cone biopsy was performed for higher grades of CIN and a selected group underwent hysterectomy. 相似文献
4.
The conformation of two Vicia villosa lectins specific for mannose and N-acetylgalactosamine, respectively, was studied by circular dichroism. Both showed a broad negative CD band around 220 nm and a positive one above 190 nm. CD data analysis indicated that they were rich in beta-sheet. However, they differed in conformational stability against extreme pH, at elevated temperature, and in guanidine hydrochloride and sodium dodecyl sulfate solutions. The unusual feature was that the conformation of N-acetylgalactosamine-specific lectin was virtually unaltered in 6 M guanidine hydrochloride and 7.5 mM surfactant. 相似文献
5.
6.
Phage Mu transposase (A-protein) is primarily responsible for transposition of the Mu genome. The protein binds to six att sites, three at each end of Mu DNA. At most att sites interaction of a protein monomer with DNA is seen to occur over three minor and two consecutive major grooves and to result in bending up to about 90 degrees. To probe the directionality and locus of these A-protein-induced bends, we have used the antitumor antibiotic (+)-CC-1065 as a structural probe. As a consequence of binding within the minor groove, (+)-CC-1065 is able to alkylate N3 of adenine in a sequence selective manner. This selectivity is partially determined by conformational flexibility of the DNA sequence, and the covalent adduct has a bent DNA structure in which narrowing of the minor groove has occurred. Using this drug in experiments in which either gel retardation or DNA strand breakage are used to monitor the stability of the A-protein--DNA complex or the (+)-CC-1065 alkylation sites on DNA (att site L3), we have demonstrated that of the three minor grooves implicated in the interaction with A-protein, the peripheral two are 'open' or accessible to drug bonding following protein binding. These drug-bonding sites very likely represent binding at at least two A-protein-induced bending sites. Significantly, the locus of bending at these sites is spaced approximately two helical turns apart, and the bending is proposed to occur by narrowing of the minor groove of DNA. The intervening minor groove between these two peripheral sites is protected from (+)-CC-1065 alkylation. The results are discussed in reference to a proposed model for overall DNA bending in the A-protein att L3 site complex. This study illustrates the utility of (+)-CC-1065 as a probe for protein-induced bending of DNA, as well as for interactions of minor groove DNA bending proteins with DNA which may be masked in hydroxyl radical footprinting experiments. 相似文献
7.
J Rhodes A Dave MC Pulling RL Geggel GR Marx DR Fulton ZM Hijazi 《Canadian Metallurgical Quarterly》1998,81(10):1217-1219
Data from exercise tests, echocardiograms, and lung perfusion scans were analyzed to determine whether the excessive minute ventilation (VE) often encountered among patients with tetralogy of Fallot is due to ventilation-perfusion mismatch secondary to branch pulmonary artery stenoses. Patients with branch PA stenoses had lower peak oxygen consumptions and higher VE during exercise than did patients without stenoses, and a strong correlation existed between the degree of pulmonary blood flow maldistribution on lung perfusion scan and the amount of excessive VE during exercise. 相似文献
8.
OBJECTIVES: This study assessed the effectiveness of a family planning intervention with and without husband's participation in reducing pregnancy and abortion rates in Shanghai, China. METHODS: In this 3-arm randomized trial among 1800 nonsterilized married women, educational interventions targeting both spouses and targeting the wife only were compared with usual family planning care. RESULTS: Among women not using intrauterine devices (IUDs), the intervention with husband's participation had an effect in reducing pregnancy rates (adjusted odds ratio [OR] = 0.36, 95% confidence interval [CI] = 0.12, 1.1) and abortion rates (adjusted OR = 0.29, CI = 0.09, 0.94) compared with control subjects, and a significant effect in reducing pregnancy rates (adjusted OR = 0.29, CI = 0.10, 0.85) and abortion rates (adjusted OR = 0.24, CI = 0.07, 0.77) compared with wife-only subjects. CONCLUSIONS: Family planning interventions involving husbands may reduce pregnancy and abortion rates among non-IUD users. 相似文献
9.
M Suzuki N Ohte ZM Wang DL Williams WC Little CP Cheng 《Canadian Metallurgical Quarterly》1998,39(3):589-599
Retrograde transport from the Golgi to the ER is an essential process. Resident ER proteins that escape the ER and proteins that cycle between the Golgi and the ER must be retrieved. The interdependence of anterograde and retrograde vesicle trafficking makes the dissection of both processes difficult in vivo. We have developed an in vitro system that measures the retrieval of a soluble reporter protein, the precursor of the yeast pheromone alpha-factor fused to a retrieval signal (HDEL) at its COOH terminus (Dean, N., and H.R.B Pelham. 1990. J. Cell Biol. 111:369-377). Retrieval depends on the HDEL sequence; the alpha-factor precursor, naturally lacking this sequence, is not retrieved. A full cycle of anterograde and retrograde transport requires a simple set of purified cytosolic proteins, including Sec18p, the Lma1p complex, Uso1p, coatomer, and Arf1p. Among the membrane-bound v-SNAP receptor (v-SNARE) proteins, Bos1p is required only for forward transport, Sec22p only for retrograde trafficking, and Bet1p is implicated in both avenues of transport. Putative retrograde carriers (COPI vesicles) generated from Golgi-enriched membranes contain v-SNAREs as well as Emp47p as cargo. 相似文献
10.
CD Carroll H Patel TO Johnson T Guo M Orlowski ZM He CL Cavallaro J Guo A Oksman IY Gluzman J Connelly D Chelsky DE Goldberg RE Dolle 《Canadian Metallurgical Quarterly》1998,8(17):2315-2320
An encoded 13,020-member combinatorial library was synthesized containing a statine core. Evaluation of this library with plasmepsin II, an aspartyl protease required for hemoglobin metabolism in the malaria parasite, led to the identification of potent and selective inhibitors as well as novel structure-activity relationships. 相似文献