全文获取类型
收费全文 | 616篇 |
免费 | 24篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 43篇 |
综合类 | 1篇 |
化学工业 | 184篇 |
金属工艺 | 21篇 |
机械仪表 | 36篇 |
建筑科学 | 5篇 |
能源动力 | 20篇 |
轻工业 | 53篇 |
水利工程 | 6篇 |
石油天然气 | 2篇 |
无线电 | 21篇 |
一般工业技术 | 128篇 |
冶金工业 | 33篇 |
原子能技术 | 27篇 |
自动化技术 | 61篇 |
出版年
2023年 | 3篇 |
2022年 | 7篇 |
2021年 | 20篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2018年 | 10篇 |
2017年 | 13篇 |
2016年 | 15篇 |
2015年 | 19篇 |
2014年 | 24篇 |
2013年 | 35篇 |
2012年 | 30篇 |
2011年 | 38篇 |
2010年 | 24篇 |
2009年 | 28篇 |
2008年 | 23篇 |
2007年 | 27篇 |
2006年 | 26篇 |
2005年 | 23篇 |
2004年 | 16篇 |
2003年 | 23篇 |
2002年 | 21篇 |
2001年 | 18篇 |
2000年 | 11篇 |
1999年 | 12篇 |
1998年 | 11篇 |
1997年 | 8篇 |
1996年 | 11篇 |
1995年 | 7篇 |
1994年 | 11篇 |
1993年 | 12篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 6篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 4篇 |
1986年 | 4篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1982年 | 8篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1973年 | 2篇 |
排序方式: 共有641条查询结果,搜索用时 15 毫秒
631.
Aiko Kawashima Ikuyo Tsukamoto Tomoko Koyabu Yasuko Murakami Takayo Kawakami Naoko Kakibuchi Kouichi Takaguchi Keiji Kita Misako Okita 《Lipids》2008,43(4):325-333
Eicosapentaenoic acid (EPA) (1.8 g/day) was administered to 12 chronic hepatitis C patients receiving combination therapy
of pegylated interferon (PEG-IFN) α-2b and ribavirin for 48 weeks (EPA group). Twelve patients were not administered EPA (control
group). All patients also received vitamin E and C (300, 600 mg/day, respectively) during the therapy. Serum alanine aminotransferase
improved to a normal level in 8 of 12 patients from the EPA group and 6 of 12 patients from the control group after 12 weeks.
Lymphocyte counts decreased significantly after 8 weeks in the control group, but not the EPA group. T-helper (Th) 1 decreased
after 4 weeks in the control group, but not in the EPA group (two-way ANOVA; P < 0.05). Th1/Th2 ratios were elevated in 9 of 12 patients in the EPA group, and 3 out of 12 in the control group (P < 0.05) after 8 weeks. After 12 weeks, the arachidonic acid/EPA molar ratio of erythrocyte membrane phospholipid correlated
negatively with the leukocyte count (n = 24, r = −0.439, P < 0.05) and the neutrophil count (n = 24, r = −0.671, P < 0.02). The hemoglobin level improved after 48 weeks compared with 24 weeks in only the EPA group. These findings suggest
that EPA supplementation may be useful in therapy for chronic hepatitis C. 相似文献
632.
Keiji Komatsu Tetsuo Sekiya Ayumu Toyama Yasuhiro Hasebe Atsushi Nakamura Masahiro Noguchi Yu Li Shigeo Ohshio Hiroki Akasaka Hiroyuki Muramatsu Hidetoshi Saitoh 《Journal of Thermal Spray Technology》2014,23(5):833-838
R2O3 (R = Y, Eu, Er) metal oxides were synthesized from metal–ethylenediaminetetraacetic acid (EDTA) complexes using a flame spray technique. As this technique enables high deposition rates, films with thickness of several tens of micrometers were obtained. Films of yttria, europia, and erbia phase were synthesized on stainless-steel substrates with reaction assistance by H2–O2 combustion gas. The oxide films consisted of the desired crystalline phase with micropores. The porosity of the films was in the range of 6–15%, varying with the metal used. These results suggest that the true density of the metal oxide obtained from metal–EDTA powder through the thermal reaction process plays an important role in achieving film with the desired porosity. 相似文献
633.
We are presenting the first quantum chemical molecular dynamics (QM/MD) model simulations for iron catalyzed single-walled carbon nanotube (SWNT) growth based on the density functional tight binding (DFTB) quantum chemical potential. As model systems, open-ended (10,10) armchair tube fragments were selected with 0, 10, and 20 Fe atoms attached in 1,4-positions on the open rims, and ensembles of randomly oriented C2 molecules were included to simulate carbon plasma feedstock molecules. Isokinetic trajectories at 1500 K to 3000 K show that divalent Fe increases the number of coordination partners with carbon and/or Fe, depending on the Fe concentration. Fe/C interactions weaken the tube sidewall due to electron transfer from Fe into antibonding carbon orbitals, and C2 addition occurs mainly in an Fe-C2-Fe bridge addition mechanism, while growth of polyyne chains characteristic for high-temperature carbon systems is suppressed in the presence of Fe on the rims of the growing SWNT. Our findings are the first quantum chemical evidence for the importance of intermetallic interactions during SWNT growth. 相似文献
634.
Mesangial expansion and glomerular basement membrane (GBM) thickening were not different between normoalbuminuric (NA) and microalbuminuric (MA) type 2 diabetic patients. The quick-freezing and deep-etching (QF-DE) method allows us to examine three-dimensional ultrastructures of human renal glomeruli in vivo at high resolution. In the present study, the QF-DE method was applied to the renal biopsy from 6 type 2 diabetic patients without definable renal diseases other than diabetic nephropathy. Four patients were NA and the other two were MA. Three control specimens were normal parts in surgically resected kidneys of renal cell carcinoma. Replica membranes were prepared by the QF-DE method as previously described. By the QF-DE method, both GBM middle layer and mesangial matrix (MM) were composed of polygonal meshwork structures. The mesh pores of GBM and MM were more enlarged in size and irregular in shape in NA diabetic patients than those of the controls, and these ultrastructural changes became more obvious in MA patients. The diameters of mesh pores in the diabetic patients were significantly larger than those in the control subjects. In conclusion, the QF-DE method could be applied to needle renal biopsy and the present study has firstly clarified the difference of ultrastructural changes between NA and MA type 2 diabetic patients, which had not been disclosed by the conventional electron microscopy, were revealed by the QF-DE method. 相似文献
635.
Regional groundwater prediction model using automatic parameter calibration SCE method for a coastal plain of Seto Inland Sea 总被引:2,自引:0,他引:2
Operational groundwater prediction models vary in complexity, but most of them have parameters for which values must be estimated.
In the present study, the proposed regional groundwater prediction model was based on a nonlinear water balance model, which
is very easy to be used once its parameters were determined. The traditional procedure of the model calibration was done manually
using a trial and error process of parameter adjustments. In this case, the goodness-of-fit of the calibrated model is based
on a visual judgment by comparing the simulated and the observed data. It requires considerable training or experience and
is also typically laborious and time consuming. Thus, this paper proposed an approach, which considered the possibilities
of using a nonlinear optimization technique -- the Shuffled Complex Evolution (SCE) method to calibrate the groundwater model.
The applicability of this technique was demonstrated with a case study for a coastal plain in Japan. The performance of the
groundwater model with SCE method was evaluated by comparing the measured and predicted data. 相似文献
636.
Although the number of cheese manufacturing units in Hokkaido had increased every year and exceeds 60, many of these units are small-scale processors. We examined the cheese produced in Hokkaido for the presence of Staphylococcus aureus for 3 years after 2002. During the study period, S. aureus was isolated from 38 cheese samples: 3.6 to 9.2% of the total cheese samples examined and 13.0 to 20.0% of the total mozzarella-type cheese samples. The largest population of S. aureus was 2.0 x 10(4) CFU/g. The isolated S. aureus strains were subjected to PCR analysis to look for seven se genes. Of the 38 isolates, 20 did not possess the se gene, but the remaining 13 isolates had seg and sei genes. No enterotoxins were detected in the cheese samples analyzed with a commercial kit. 相似文献
637.
Koji?Matsuura Kuan-Hung?Chen Cheng-Han?Tsai Wenqian?Li Yuka?Asano Keiji?Naruse Chao-Min?ChengEmail author 《Microfluidics and nanofluidics》2014,16(5):857-867
Male infertility, which amounts to half of all infertility cases, is a serious problem worldwide. The percentage of fertility-related patients in sub-Saharan African countries is higher than that for the developed countries. In low-resource countries, examination of sperm characteristics for male infertility cannot be undertaken because of poor clinical access. To evaluate male fertility in assisted reproductive medicine laboratories, the numbers of motile human sperm, the degree of sperm motility, and sperm morphology have been commonly analyzed using a microscope. It is challenging to monitor the health status of human sperm in resource-limited or remote settings for two primary reasons: (1) high capital cost (equipment for currently accepted procedural standard), and (2) complexity of the currently accepted procedural standard used to simultaneously measure human sperm concentration and motility by skillful embryologists. Determining the health status of human sperm in order to evaluate fertilization capacity using various types of low-cost, easy-to-use, and rapid devices (or systems) is a longstanding but interesting biotechnologically relevant issue in various scientific communities such as male reproduction. Furthering such efforts will inherently influence birth rate in both developed and developing nations. We have demonstrated an inexpensive but robust and easy-to-handle device for monitoring the health status of human sperm made by patterning a piece of paper and measuring the activity of a specific enzyme—a simple and elegant solution. After applying semen to the hydrophilic center circle of our patterned paper, a thiazine assay can be used to suggest sperm concentration in semen, and a tetrazolium-based colorimetric assay (MTT assay) data can be used to help estimate the percentage of motile human sperm (sperm motility) in semen based on the character that motile human sperm moved in and on the paper. Using this paper-based device, we can evaluate fertility levels without consulting doctors and use our assay to compare results with World Health Organization (WHO) reference values for sperm concentration (>2×107) and motility (>50 %). The duration and cost of one entire test are 30 min and 0.1 USD, respectively. We believe that this paper-based assay system would be useful for fertility checks based on WHO references, without need of a microscope, at home. Using this assay method, males in developed or developing countries who are reluctant or unable to consult assisted reproductive technologies clinics can self-analyze their sperm characteristics. We further note that our approach adheres to WHO regulations, especially in regard to in vitro diagnostic device performance with an associated diagnostic algorithm to enhance diagnostic accuracy (compared with just one diagnostic output), and we wish to emphasize that our research could significantly advance a broad range of diagnostic developments including paper-based diagnostic devices, in vitro diagnostic devices, and diagnosis of other diseases in various divisions of translational medicine. These results, we believe, will be of interest to a wide scientific audience working in materials science (biomaterials), chemistry (analytical and clinical), lab-on-a-chip technologies (the development of diagnostic tools), reproductive medicine, bioengineering, and translational medicine. 相似文献
638.
Hajime Yamashina Susumu Okumura Keiji Kimura 《Journal of Intelligent Manufacturing》1993,4(4):259-267
This paper describes the development of a non-destructive inspection method for cracks in a trolley conveyor chain, using a high-frequency electric current heater and an infrared radiation camera. This method is based on the idea that cracks affect heat conduction in the chain. When the chain is heated properly with the heater, variations in the heat conduction can be detected by monitoring the surface temperature of the chain with the infrared camera. The effectiveness of the proposed method is shown by a numerical analysis of the heat conduction in the chain. It is confirmed that the method is applicable to the chain which consists of portions with high and low emissivity, and that it is not affected by oil mixed with wear debris on the chain surface or by the operation speed of the conveyor. 相似文献
639.
At present, there is a growing demand for energy saving to prevent global warming. Thus, the railway industry is also focusing on energy saving methods. Power consumption of running trains has a large variation of approximately 20% caused by drivers’ operation. Therefore, improving the running profile can considerably reduce energy consumption. Numerous algorithms for generating energy saving running profiles have been researched and developed. To adapt energy saving operation to various environments, we developed a technology that maintains punctuality without reducing the energy efficiency when temporary differences occur in driving conditions. We propose a method that determines the re-creation command point to complete the re-creation at the switching point of the driving operation in the existing energy-saving target pattern, to achieve both punctuality and ride comfort. As a result of verifying the effect of the proposed method on the conventional method via a simulation, it was confirmed that the proposed method can prevent the increase in the number of operation changes when the driving conditions change, whereas the conventional method increases the number of operation changes. 相似文献
640.
Keiji Saiki Toshihiro Ishikawa 《International Journal of Applied Ceramic Technology》2023,20(3):1388-1397
Silica–titania mixed oxides have excellent properties, such as a low thermal expansion coefficient and a refractive index that can be adjusted by changing the Ti content. However, when the Ti content increases, silica and titania phases in silica–titania mixed oxides can separate. This phase separation leads to the precipitation of the titania component as rutile or anatase crystals. When silica–titania mixed oxides undergo phase separation, their properties become unstable; for example, the refractive index of the particles becomes non-uniform. Therefore, it is preferable to synthesize silica–titania mixed oxides in an amorphous state without causing phase separation. Based on our previous studies on particle size control in silica synthesis, we employed a dry process using organosilicon compounds to synthesize silica–titania mixed oxides. In this study, spherical amorphous silica–titania mixed oxide particles were obtained via flame synthesis using organosilicon and organotitanium compounds. The purpose of this study was to characterize the obtained powder and explore the possibility of controlling particle size during synthesis. By studying the dry process synthesis of spherical silica–titania mixed oxide particles, we confirmed the relationships: between the Si/Ti molar ratio and the obtained crystal structure and between the adiabatic flame temperature and the particle size. 相似文献