全文获取类型
收费全文 | 1027篇 |
免费 | 3篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 25篇 |
机械仪表 | 4篇 |
建筑科学 | 3篇 |
能源动力 | 8篇 |
轻工业 | 5篇 |
无线电 | 41篇 |
一般工业技术 | 10篇 |
冶金工业 | 915篇 |
原子能技术 | 2篇 |
自动化技术 | 14篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 5篇 |
2019年 | 5篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 4篇 |
2015年 | 4篇 |
2014年 | 4篇 |
2013年 | 3篇 |
2012年 | 9篇 |
2011年 | 8篇 |
2010年 | 4篇 |
2009年 | 3篇 |
2008年 | 4篇 |
2007年 | 5篇 |
2006年 | 8篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 3篇 |
1999年 | 26篇 |
1998年 | 256篇 |
1997年 | 158篇 |
1996年 | 104篇 |
1995年 | 58篇 |
1994年 | 48篇 |
1993年 | 53篇 |
1992年 | 6篇 |
1991年 | 11篇 |
1990年 | 19篇 |
1989年 | 12篇 |
1988年 | 14篇 |
1987年 | 15篇 |
1986年 | 11篇 |
1985年 | 14篇 |
1983年 | 6篇 |
1982年 | 5篇 |
1981年 | 11篇 |
1980年 | 11篇 |
1978年 | 6篇 |
1977年 | 24篇 |
1976年 | 64篇 |
1974年 | 1篇 |
1955年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1030条查询结果,搜索用时 15 毫秒
991.
BE Cavallaro WP Madigan MA O'Hara KK Kramer WC Bauman 《Canadian Metallurgical Quarterly》1998,35(5):254-263
PURPOSE: The authors report on the efficacy of intraocular lens implantation during pediatric cataract surgery and the results of a consecutive series of intraocular lens implantation in children. METHODS: Twenty-one children underwent implantation of intraocular lenses in 23 eyes. Twenty-one surgeries were primary implantation immediately following anterior lensectomy. Two surgeries were secondary implantations. Primary posterior capsulectomy was performed in 18 of 21 primary implantations. All but two eyes underwent a primary anterior vitrectomy. Topical prednisolone acetate was administered in all cases. Oral prednisone was administered in 17 of 23 cases. Pre- and postoperative visual acuity, cycloplegic refraction, and postoperative complications related to inflammation such as intraocular lens (IOL) capture, IOL decentration, and posterior capsule opacification were examined. RESULTS: Eighteen of 23 eyes have achieved a visual acuity of 20/40 or better. None of the cases in which oral prednisone was used developed complications related to postoperative inflammation. One of the six cases (17%) in which oral prednisone was not used developed such complications. CONCLUSION: Intracular lens implantation accompanied by primary posterior capsulectomy, anterior vitrectomy, and management of postoperative inflammation appears to provide appropriate and safe optical rehabilitation in children. 相似文献
992.
The influence of lipopolysaccharide (LPS) expression on the sensitivity of Neisseria meningitidis to serum bactericidal activity was investigated by using a series of variants that expressed different LPS determinants. For each of two different strains, a series of three LPS variants that expressed L3,7, L8, or both were analyzed. LPS variants were identified and monitored by colony blotting with murine monoclonal antibodies specific for the L8 or the L3,7,9 immunotype determinants. Differences in LPS expression were verified by analysis of proteinase K lysates of whole cells by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and then by silver staining or immunoblotting. The variants were used as test strains in bactericidal assays with human sera and with murine sera and monoclonal antibodies. Expression of the L8 LPS epitope was correlated with increased sensitivity to serum bactericidal activity. The geometric mean bactericidal titers of 12 to 16 sets of pre- and postvaccination sera were determined for each variant. Mean serum titers increased progressively with increased expression of L8 on the target strain. The bactericidal titers of anti-outer membrane protein monoclonal antibodies also increased with increased L8 expression. 相似文献
993.
994.
995.
NS Loginova AS Kinzirski? OV Parshina EE Mirskaia FI Ershov 《Canadian Metallurgical Quarterly》1996,59(3):28-33
The in vitro study on an isolated system of myocardial contractile proteins determined optimal concentrations of the positive inotropic action and biological activity ranges of beta-methyldigoxin (beta-MD), strophanthin K, K-strophantozide, beta-acetyldigoxin (beta-AD), milrinone, and amrinone. Optimal concentrations of the beta-MD and strophanthin K (10(-2) and 10(-6) M, respectively) significantly increased qualitatively and quantitatively the economy and thermodynamic efficiency, altered the energy transformation in the contractile protein system under the isometric contraction, whereas the beta-AD produced only the quantitative effect. However, the beta-MD and strophanthin K at concentrations exceeding the optimal one by one order lost the ability to produce the qualitative effect, retaining only the quantitative one in the actomyosin ensemble. The strophanthin K significantly increased the economy of a single actomyosin ensemble in the force generation phase and the beta-MD in the tension maintenance phase. Unlike the strophanthin K, the beta-MD did not slow down (did not worsen) the relaxation process. This provides grounds to conclude that the beta-MD produces most favorable effect on the energy transformation by myocardial contractile proteins. 相似文献
996.
KA McGarvey AP Zis EE Brown GG Nomikos HC Fibiger 《Canadian Metallurgical Quarterly》1993,34(3):152-157
BACKGROUND AND OBJECTIVES: The detection of asymptomatic urethritis using a leukocyte esterase (LE) strip may have a role in primary care screening to select men who need diagnostic testing for Chlamydia trachomatis and Neisseria gonorrhoeae. STUDY DESIGN: Eight-hundred and eighty-two men, 16 to 35 years of age were studied when they attended their family physician or university health clinic for nongenitourinary complaints. First void urine (FVU) was tested by an LE strip (Chemstrip 2 LN, Boehringer Mannheim Corp., Indianapolis, IN), Chlamydiazyme (Abbott Laboratories, N. Chicago, IL) enzyme immunoassay with confirmatory blocking and polymerase chain reaction (PCR) with chlamydial plasmid primers. RESULTS: Forty-five men (5.1%) were positive (> trace) by LE strip. Of the LE-positive urines, 9 (20.0%) were positive by EIA or PCR, and none of the LE-negatives were positive by EIA or PCR. Twenty-three LE positives (5 EIA/PCR-positive; 1 PCR-positive; 17 EIA/PCR-negative) were able to be followed with a second urine and 2 urethral swabs. All of the 6 chlamydia-positives who had follow-up tests were positive by both immunoassay and PCR on urine. Based on the FVU results, the prevalence of asymptomatic chlamydial infection was 1.0% (9/88) (95% CL, 0.5 to 1.9) for which the LE urine strip was 100% (9/9) sensitive and 95.9% (837/873) specific. Analyses based on screening 1,000 men, 16 to 25 years of age, showed that the cost per case detected was $192.00 using the LE strip (> 1+) to select urine specimens for EIA testing, compared to $1,326.00 using the EIA to test all urine specimens. CONCLUSION: In this low prevalence, primary care setting, the LE urine strip was an accurate screening test, which if used to preselect urine specimens for subsequent chlamydial testing, would be less costly per case detected than assaying each specimen for chlamydia. 相似文献
997.
A water-mediated hydrogen bond network coordinated by glutamate 60(58) appears to play an important role in the thymidylate synthase (TS) reaction mechanism. We have addressed the role of glutamate 60(58) in the TS reaction by cocrystalizing the Escherichia coli TS mutant E60(58)Q with dUMP and the cofactor analog CB3717 and have determined the X-ray crystal structure to 2.5 A resolution with a final R factor of 15.2% (Rfree = 24.0%). Using difference Fourier analysis, we analyzed directly the changes that occur between wild-type and mutant structures. The structure of the mutant enzyme suggests that E60(58) is not required to properly position the ligands in the active site and that the coordinated hydrogen bond network has been disrupted in the mutant, providing an atomic resolution explanation for the impairment of the TS reaction by the E60(58)Q mutant and confirming the proposal that E60(58) coordinates this conserved hydrogen bond network. The structure also provides insight into the role of specific waters in the active site which have been suggested to be important in the TS reaction. Finally, the structure shows a unique conformation for the cofactor analog, CB3717, which has implications for structure-based drug design and sheds light on the controversy surrounding the previously observed enzymatic nonidentity between the chemically identical monomers of the TS dimer. 相似文献
998.
AA Filaretov LP Filaretova AI Bogdanov FN Makarov EE Granstrem IuI Levkovich NA Mal'tsev 《Canadian Metallurgical Quarterly》1996,82(3):141-150
The influence of stress-induced corticosteroid production on gastric ulceration, blood flow velocity in gastric microvessels and blood pressure was studied in rats. The role of plasma corticosteroids was investigated by means of blockade of the pituitary-adrenocortical system (PACS) and following corticosterone replacement therapy (400 mu/100 g b.w.). The blockade which was induced by Fi. hydrocortisone administration (7 days before stress, 30 mg/100 g b. w.) resulted in an insufficient corticosteroid production. To evaluate the influence of corticosteroids on blood flow velocity in gastric microvessels of muscular, submucosal and mucosal coats it was used intravital microfilming by means of a dark-field contact epiobjective. Stress (water immersion + restraint) induces an ulceration, a decrease in the systemic arterial blood pressure (3 h after stress onset) and a decrease in blood flow velocity in the gastric microvessels (3 h after stress onset). In rats with insufficient corticosteroid production stress-induced ulceration, a decrease in blood pressure and gastric blood velocity were more greater than in rats with intact PACS. Replacement corticosterone therapy corrected all parameters. The results revealed that antiulcerogenic effect of stress-induced glucocorticoid production is realised owing to normalisation of gastric blood supply which is provided by an increase in systemic blood pressure. 相似文献
999.
Pharyngeal lipoma with cartilaginous metaplasia (chondrolipoma): a case report and literature review
OG Nwaorgu EE Akang BM Ahmad FN Nwachokor AN Olu-Eddo 《Canadian Metallurgical Quarterly》1997,111(7):656-658
We report two cases of vasospastic angina associated with anaphylactic reaction caused by nonsteroidal anti-inflammatory drugs (NSAIDs). Both patients exhibited anaphylactic manifestations, such as general rash and urticaria, along with angina pectoris with electrocardiographic ST-segment elevations after suppository administration of diclofenac sodium or indomethacin, the most commonly used NSAIDs. Although these patients had normal coronary arteriograms, intracoronary administration of ergonovine or acetylcholine provoked diffuse coronary artery spasms accompanied by chest pain and ischemic ST-segment changes. It is therefore suggested that an allergic mechanism may be involved as a causative factor of the coronary artery spasm induced by NSAIDs. 相似文献
1000.
Yersinia was isolated from imported raw meat and fowl products by HeLa cell treatment and conventional KOH-treatment, to obtain information on the origin of pathogenic Yersinia in Japan. Forty-one strains of Yersinia enterocolitica and one strain of Yersinia pseudotuberculosis, serotype 4b were isolated from 38 (3.0%) of 1278 samples of pork, two (0.3%) of 612 samples of beef and two (0.3%) of 615 samples of chicken. Y. enterocolitica isolates belonged to B:4/O:3 (biotype/serotype, 15 strains), B:3/O:3 (two strains) and B:3 variant/O:3 (17 strains) and B:3/O:5.27 (seven strains). The B:4/O:3 which is globally prevalent among humans and animals was isolated from pork samples from Denmark and the US and from beef samples from Australia, the B:3/O:3 from pork samples from Canada, the B:3 variant/O:3 from pork samples from Taiwan and from chicken samples from Thailand, the B:3/O:5.27 from pork samples from the US and Taiwan and Y. pseudotuberculosis, serotype 4b from pork samples from Canada. These findings suggest that pathogenic Y. enterocolitica strains can be introduced into Japan by the import of pork from pig producing countries. The HeLa cell treatment was found to be superior to the conventional method. 相似文献