全文获取类型
收费全文 | 1582篇 |
免费 | 90篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 15篇 |
综合类 | 1篇 |
化学工业 | 391篇 |
金属工艺 | 34篇 |
机械仪表 | 50篇 |
建筑科学 | 37篇 |
矿业工程 | 4篇 |
能源动力 | 23篇 |
轻工业 | 219篇 |
水利工程 | 12篇 |
石油天然气 | 11篇 |
无线电 | 64篇 |
一般工业技术 | 282篇 |
冶金工业 | 392篇 |
原子能技术 | 11篇 |
自动化技术 | 128篇 |
出版年
2024年 | 4篇 |
2023年 | 20篇 |
2022年 | 40篇 |
2021年 | 67篇 |
2020年 | 30篇 |
2019年 | 44篇 |
2018年 | 51篇 |
2017年 | 62篇 |
2016年 | 60篇 |
2015年 | 30篇 |
2014年 | 44篇 |
2013年 | 97篇 |
2012年 | 78篇 |
2011年 | 71篇 |
2010年 | 69篇 |
2009年 | 66篇 |
2008年 | 55篇 |
2007年 | 54篇 |
2006年 | 46篇 |
2005年 | 32篇 |
2004年 | 30篇 |
2003年 | 28篇 |
2002年 | 43篇 |
2001年 | 24篇 |
2000年 | 17篇 |
1999年 | 30篇 |
1998年 | 133篇 |
1997年 | 93篇 |
1996年 | 59篇 |
1995年 | 49篇 |
1994年 | 29篇 |
1993年 | 29篇 |
1992年 | 7篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1978年 | 4篇 |
1977年 | 6篇 |
1976年 | 21篇 |
1975年 | 2篇 |
排序方式: 共有1674条查询结果,搜索用时 0 毫秒
1.
In a prospective study of layered versus mass closure of abdominal incisions in infants and children, 34 cases underwent wound closure by layered and mass closure technique on an alternate basis. All the patients were assessed for their nutritional status and haemoglobin level pre-operatively, and wound complications were compared with respect to closure technique, nutritional status and normal haemoglobin level. Presence of protein energy malnutrition and anaemia did not increase the risk of wound complications with either of the technique. 相似文献
2.
VC Jordan 《Canadian Metallurgical Quarterly》1997,6(3):257-259
INTRODUCTION: Parvovirus B19 infection is frequent. Primary infection leads to diverse skin manifestations including the recently described gloves-and-socks papulopurpura. CASE REPORT: A patient presented with a papulopurpuric eruption on the nose, hands, feet and perineum with cheilitis and high-grade fever. Parvovirus B19 serology showed characteristic IgG on the 15th day after the initial eruption demonstrating the seroconversion. Cold agglutinins were positive during the eruption and negative after regression. DISCUSSION: The gloves-and-socks papulopurpura syndrome was initially described in 1990. Since that time 20 cases have been reported. In 7 cases, primary parvovirus B19 infection was proven and viral infections were suspected in the others (measles, coxsackie B6, hepatitis B, Epstein-Barr virus). Our case evidenced here to undescribed skin manifestations and the development of cold agglutinins. The presence of cold agglutinins at eruption could explain the acral localizations observed in this syndrome. 相似文献
3.
Talita Moreira de Oliveira Nilda de Fátima Ferreira Soares Rodrigo Magela Pereira Kátia de Freitas Fraga 《Packaging Technology and Science》2007,20(2):147-153
Conservation of food products depends on product quality and packaging suitability. The objective of this work was to develop and evaluate the antimicrobial efficiency of natamycin‐incorporated film in the production process of Gorgonzola cheese. It aims to optimize the production process and increase shelf‐life and food safety for the consumer. Films with different concentrations of natamycin were produced and tested in Gorgonzola cheeses to evaluate its efficiency against Penicillium roqueforti on the cheese surface. Films with 2 and 4% natamycin presented satisfactory results for fungus inhibition and the amount of natamycin released to the cheese was below that allowed by the legislation. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
4.
F Zindy H Soares KH Herzog J Morgan CJ Sherr MF Roussel 《Canadian Metallurgical Quarterly》1997,8(11):1139-1150
In situ hybridization of mouse embryo sections demonstrated expression of mRNAs encoding two polypeptide inhibitors (p18INK4c and p19INK4d) of cyclin D-dependent kinase (CDK) 4 and CDK6 in the central nervous system. No expression of two other INK4 members, p16INK4a and p15INK4b, was observed. The p19INK4d and p18INK4c proteins formed complexes with either CDK4 or CDK6 in a temporal pattern consistent with the results of in situ hybridization. Expression of INK4c was observed at embryonic day 13.5 in neuroepithelial zones of the developing brain, being restricted to dividing neuroblasts but absent from differentiating postmitotic neurons. In the neocortex, p18INK4c was expressed precisely at those developmental stages when neuroblasts switch from a symmetric to an asymmetric pattern of cell division with concomitant increases in their G1 interval. INK4d RNA was detected from embryonic day 11.5 onward, at higher levels than INK4c and with a distinctly different spatial and temporal pattern. Marked INK4d expression was seen in dorsal root ganglia, spinal cord, and focally throughout the brain, but primarily in postmitotic neurons. Neural expression of INK4d continued postnatally into adulthood in postmitotic cells of the dentate gyrus, the pyramidal layer of the hippocampus, and in discrete regions of the cerebral cortex, cerebellum, thalamus, and brainstem. Downregulation of p19INK4d in the dentate gyrus after kainic acid-induced seizures indicated that its expression could also be modified in nondividing cells by excitotoxic stress. Therefore, p19INK4d may contribute to maintaining the quiescent state, acting as a buffer to prevent reactivation of cyclin D-dependent kinases in terminally differentiated cells. 相似文献
5.
OM Takayanagui AA Castro e Silva RC Santiago NS Odashima VC Terra AM Takayanagui 《Canadian Metallurgical Quarterly》1996,54(4):557-564
Cysticercosis is a severe public health problem in several regions of Asia, Africa and Latin America. Epidemiologic studies based on the frequency of cases observed in specialized neurology, neurosurgery and computed tomography services, at autopsy and in seroepidemiologic studies do not permit the determination of the true prevalence of the disease in the population. The objective of the present study was to investigate the prevalence of cysticercosis by compulsory notification. The coefficient of prevalence was 54 cases/100,000 inhabitants in the municipality of Ribeir?o Preto. The results also indicated that cysticercosis is not under control in our region since 21% of cases presented the active form of the disease. Compulsory notification proved to be a valuable resource for the epidemiologic study of cysticercosis, also permitting the mapping of more affected areas for a better direction of prevention strategies. 相似文献
6.
IS Han N Ramamurthy JH Yun U Schaller ME Meyerhoff VC Yang 《Canadian Metallurgical Quarterly》1996,10(14):1621-1626
A novel method to monitor specific peptidase activities in biological samples as complex as undiluted plasma/blood is described. The approach is based on the design of synthetic polypeptide substrates in which di- or triarginine sequences are linked to each other via one or more other amino acids recognized specifically by the peptidase to be determined. Detection of chymotrypsin and renin activities using synthetic substrates P4 (F-R-R-R-F-V-R-R-F-NH2) and P5 (R-R-R-L-L-R-R-L-L-R-R-R), respectively, serves to demonstrate the principles of this new assay system. A polyion-sensitive membrane electrode, prepared by doping polymer films with dinonylnaphthalene-sulfonate (DNNS), is shown to exhibit significant nonequilibrium electromotive force (EMF) responses toward these and other polycationic substrates at microgram/milliliter levels under physiological conditions. The same electrode, however, exhibits much smaller total EMF response toward the shorter fragments of the synthetic peptides generated by peptidase activity; hence, the addition of peptidase to a solution containing the synthetic substrate yields a change in electrode EMF response, the rate of which is proportional to the activity of peptidase present. Other synthetic polycationic peptides as well as natural polycationic peptides (e.g., protamine) that lack specific cleavage sites for chymotrypsin and renin, yet are detected by the DNNS-based membrane electrode, do not elicit any significant change in EMF response in the presence of the peptidases, confirming the feasibility and utility of the proposed bioanalytical method. 相似文献
7.
I Thalmann K Machiki A Calabro VC Hascall R Thalmann 《Canadian Metallurgical Quarterly》1993,307(2):391-396
The use of growth hormone (GH) as an anabolic agent is limited by its tendency to cause hyperglycemia and by its inability to reverse nitrogen wasting in some catabolic conditions. In a previous study comparing the anabolic actions of GH and IGF-I (insulin-like growth factor I), we observed that intravenous infusions of IGF-I (12 micrograms/kg ideal body wt [IBW]/h) attenuated nitrogen wasting to a degree comparable to GH given subcutaneously at a standard dose of 0.05 mg/kg IBW per d. IGF-I, however, had a tendency to cause hypoglycemia. In the present study, we treated seven calorically restricted (20 kcal/kg IBW per d) normal volunteers with a combination of GH and IGF-I (using the same doses as in the previous study) and compared its effects on anabolism and carbohydrate metabolism to treatment with IGF-I alone. The GH/IGF-I combination caused significantly greater nitrogen retention (262 +/- 43 mmol/d, mean +/- SD) compared to IGF-I alone (108 +/- 29 mmol/d; P < 0.001). GH/IGF-I treatment resulted in substantial urinary potassium conservation (34 +/- 3 mmol/d, mean +/- SE; P < 0.001), suggesting that most protein accretion occurred in muscle and connective tissue. GH attenuated the hypoglycemia induced by IGF-I as indicated by fewer hypoglycemic episodes and higher capillary blood glucose concentrations on GH/IGF-I (4.3 +/- 1.0 mmol/liter, mean +/- SD) compared to IGF-I alone (3.8 +/- 0.8 mmol/liter; P < 0.001). IGF-I caused a marked decline in C-peptide (1,165 +/- 341 pmol/liter; mean +/- SD) compared to the GH/IGF-I combination (2,280 +/- 612 pmol/liter; P < 0.001), suggesting maintenance of normal carbohydrate metabolism with the latter regimen. GH/IGF-I produced higher serum IGF-I concentrations (1,854 +/- 708 micrograms/liter; mean +/- SD) compared to IGF-I only treatment (1,092 +/- 503 micrograms/liter; P < 0.001). This observation was associated with increased concentrations of IGF binding protein 3 and acid-labile subunit on GH/IGF-I treatment and decreased concentrations on IGF-I alone. These results suggest that the combination of GH and IGF-I treatment is substantially more anabolic than either IGF-I or GH alone. GH/IGF-I treatment also attenuates the hypoglycemia caused by IGF-I alone. GH/IGF-I treatment could have important applications in diseases associated with catabolism. 相似文献
8.
Cohen S.S. Soares A.M. Gleason E.F. Wyatt P.W. Raffel J.I. 《Electron Devices, IEEE Transactions on》1993,40(7):1277-1283
A metal-insulator-metal (MIM) capacitor structure has been developed for use in field-programmable gate arrays (FPGAs) as a voltage-programmable link (VPL). The structure relies on a combination of a refractory metal and aluminum as the lower electrode, and either a similar combination or aluminum alone as the top electrode. The insulator is prepared by means of plasma-enhanced chemical vapor deposition (PECVD). It comprises a sandwich of nearly stoichiometric silicon dioxide interposed between two like layers of silicon-rich silicon nitride. The structure has displayed characteristics desirable for use in emerging FPGA technology, including high density, low on-resistance, reduced capacitance, and low programming voltage 相似文献
9.
B. Herreros G. Lifante A. Kling J.C. Soares M.F. da Silva P.D. Townsend P.J. Chandler J. Olivares J.M. Cabrera 《Optical Materials》1996,6(4):281-286
We present a structural study of two Nd3+/MgO codoped LiNbO3 waveguides fabricated by two different methods: ion-implantation and proton-exchange. Rutherford backscattering spectrometry in combination with channelling was used to study the influence of the waveguide fabrication method on the possible modification of the LiNbO3 crystal structure within the waveguiding layer. The results show that the ion-implanted waveguide mainly maintains the same properties as the virgin crystal, apart from a deterioration of a thin surface layer, whilst the proton-exchanged waveguide exhibits a quite different behaviour, although its surface is less damaged. 相似文献
10.
GA Ateshian JW Ark MP Rosenwasser RJ Pawluk LJ Soslowsky VC Mow 《Canadian Metallurgical Quarterly》1995,13(3):450-458
The thumb carpometacarpal joint is a common site of osteoarthritis. It has been hypothesized that peaks of localized stress on the dorsoradial or volar-ulnar regions, or both, of the articular surfaces of the trapezium and metacarpal lead to erosion of cartilage and may be responsible for the progression of the disease. The objective of this study was to determine the contact areas in this joint under the functional position of lateral (key) pinch and in the extremes of range of motion of the joint. These contact areas were assessed relative to the observed sites of cartilage thinning. Eight hands from cadavers of women and five from cadavers of men were tested in vitro with the thumb under a 25 N load in the lateral pinch position, and under small muscle loads (0-5 N) with the thumb in flexion, extension, abduction, adduction, and neutral positions. Contact areas of articular surfaces of the thumb carpometacarpal joint were determined for these positions using a stereophotogrammetric technique. The lateral pinch position produced contact areas predominantly on the central, volar, and volar-ulnar regions of the trapezium and the metacarpal. In three specimens, contact areas were distinctly separated between the dorsoradial and volar-ulnar regions, and in one specimen, from a man, contact occurred exclusively on the dorsoradial region of the trapezium. Using stereophotogrammetry, maps of cartilage thickness also were determined for a subset of nine specimens. The volar-ulnar, ulnar, and dorsoradial regions of the trapezium were the most common sites of thin cartilage, and these may be sites of cartilage wear.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献