全文获取类型
收费全文 | 357篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 26篇 |
化学工业 | 63篇 |
金属工艺 | 12篇 |
机械仪表 | 6篇 |
能源动力 | 25篇 |
轻工业 | 19篇 |
无线电 | 36篇 |
一般工业技术 | 78篇 |
冶金工业 | 67篇 |
原子能技术 | 13篇 |
自动化技术 | 19篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 9篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 10篇 |
2015年 | 5篇 |
2014年 | 7篇 |
2013年 | 19篇 |
2012年 | 9篇 |
2011年 | 16篇 |
2010年 | 10篇 |
2009年 | 18篇 |
2008年 | 19篇 |
2007年 | 11篇 |
2006年 | 8篇 |
2005年 | 3篇 |
2004年 | 9篇 |
2003年 | 13篇 |
2002年 | 8篇 |
2001年 | 6篇 |
2000年 | 7篇 |
1999年 | 13篇 |
1998年 | 27篇 |
1997年 | 25篇 |
1996年 | 12篇 |
1995年 | 6篇 |
1994年 | 7篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 6篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 6篇 |
1978年 | 1篇 |
1977年 | 3篇 |
1976年 | 3篇 |
1974年 | 1篇 |
排序方式: 共有364条查询结果,搜索用时 644 毫秒
81.
The prevalence of diseases associated with obesity, such as cardiovascular disease and diabetes mellitus, is higher in the spinal cord injury (SCI) population. Specifically, the mortality rate for cardiovascular disease is 228% higher in the SCI population. In addition, 100% of SCI individuals have osteoporosis in the paralysed extremities. These diseases are related to physical activity level, the level of the spinal cord lesion, and time post injury. Physically active SCI men and women have above-average fat mass (16 to 24% and 24 to 32%, respectively, compared with 15% for able-bodied men and 23% for able-bodied women), while sedentary SCI individuals have 'at-risk' levels of body fat (above 25% and 32%, respectively). The proportions and densities of the 3 main constituents comprising the fat-free body (mineral, protein and water) are altered following SCI. Bone mineral content decreases by 25 to 50%, and the magnitude of reduction is dependent on the level, completeness and duration of SCI. Because of denervation resulting in skeletal muscle atrophy, total body protein reduces by 30%, and total body water relative to bodyweight decreases by 15% following SCI. Indirect methods based on 2-component body composition models assume constant proportions and densities of mineral, protein, and water in the fat-free body. As a result, prediction equations based on 2-component models yield invalid estimates of fat and fat-free mass in the SCI population. Therefore, future research needs to directly quantify the proportions and densities of the constituents of the fat-free body in the SCI population relative to age, sex, physical activity level, level of the spinal cord lesion and time post injury, and to develop equations based on multicomponent body composition models. 相似文献
82.
This paper proposes a numerical computer method for formal linearization of nonlinear systems by using the discrete Fourier expansion. A nonlinear system is described by a system of nonlinear ordinary differential equations. A linearizing function is given by a sequence of trigonometric functions. The nonlinear terms of the differential equations are expanded into finite sums of trigonometric functions by the method of the discrete Fourier expansion. As a result, a formal linear system is derived from the given nonlinear system. A computer algorithm of the linearization is acquired and numerical computation is easily carried out with the aid of computers. Further, as the application of the linearization, both a nonlinear observer and a nonlinear filter are synthesized in this paper. Examples show that the accuracy of the method is improved as the order of the trigonometric functions increases. 相似文献
83.
84.
New materials for a transparent conducting oxide film are demonstrated. Highly transparent Zn2In2O5 films with a resistivity of 3.9 × 10−4 Ω cm were prepared on substrates at room temperature using a pseudobinary compound powder target composed of ZnO (50 mol.%) and In2O3 (50 mol.%) by r.f. magnetron sputtering. MgIn2O4---Zn2In2O5 films were prepared using MgIn2O4 targets with a ZnO content of 0–100 wt.%. The resistivity of the deposited films gradually decreased from 2 × 10−3 to 3.9 × 10−4 Ω cm as the Zn/(Mg + Zn) atomic ratio introduced into the films was increased. The greatest transparency was obtained in a MgIn2O4 film. The optical absorption edge of the films decreased as the Zn/(Mg + Zn) atomic ratio was increased, corresponding to the bandgap energy of their materials. It was found that the resistance of the undoped Zn2In2O5 films was more stable than either the undoped MgIn2O4, ZnO or In2O3 films in oxidizing environments at high temperatures. 相似文献
85.
Skin permeation of amino acids through excised rat skin was measured at various pH values. The permeabilities varied with the donor pH and amino acid, indicating that each ionic species of amino acid may have a different permeability. The permeability coefficient of each ion was estimated from the permeability-pH profiles using the dissociation constants. The estimated values for mono-cation and uncharged zwitterion were not dependent on the lipophilicity but on the size of the amino acid, suggesting a porous mechanism of transport. The permeability coefficient was highest for di-cation, followed by mono-cation, positively charged, uncharged and negatively charged zwitterions. The electrical potential difference across the skin was too small to affect the permeation of ions. The permselective property of skin thus seems to be determined by the difference of diffusivity in aqueous pores of skin due to the hydration of ions and other factors. 相似文献
86.
T Murata Y Matsumoto T Suzuki K Naito I Takata K Tsuzurahara 《Canadian Metallurgical Quarterly》1997,46(7):576-584
We investigated the effect of betotastine besilate (betotastine) on the experimental allergic rhinitis. The oral administration of betotastine (1, 3 and 10 mg/kg) inhibited the increase in dye leakage during and after the nasal perfusion of antigen in actively sensitized rats. It also prevented the increase in intranasal pressure induced by topically applied histamine in non-sensitized guinea pigs. Cetirizine and terfenadine dose-dependently inhibited the increase in a similar manner. Ketotifen (0.01-0.3 mg/kg, p.o.) inhibited the increase more than 50% at 0.01 mg/kg. The ID50s of ketotifen, cetirizine, betotastine and terfenadine for this model were more than 0.01 mg/kg, 0.01 mg/kg, 0.03 mg/kg and 0.5 mg/kg, respectively. Furthermore, in actively sensitized guinea pigs, nasal airway resistance showed a biphasic increase after the topical antigen challenge to the nasal cavity; the first peak at 0.5 hr and a second peak at 4 hr. Both the responses of first and second peaks were significantly inhibited by orally administered betotastine besilate, and its inhibitory effect on the second peak was the strongest among drugs tested. Since betotastine showed significantly inhibitory effects in experimental allergic rhinitis models, it was suggested to show a good efficacy for the treatment of allergic rhinitis clinically. 相似文献
87.
H Tamada H Kanai Y Sakuma K Takata I Yoshida T Sakuma K Yamamoto 《Canadian Metallurgical Quarterly》1997,43(7):517-520
We report a case of testicular tumor detected by ultrasonography during the prenatal period. Ultrasonography performed at 32 weeks of gestation showed that one testis was larger than the other. The right testis was markedly enlarged at 38 weeks of gestation. The heterogeneous echo pattern of the right testis suggested a testicular tumor. Right high orchiectomy was performed 3 months after birth. Pathological findings of the tumor were teratoma with mature and immature components according to the histological classification of testicular tumor. In Japan, this is the second case diagnosed in the prenatal period using ultrasonography. 相似文献
88.
Y Segawa N Takigawa M Okahara Y Maeda I Takata M Fujii H Mogami K Mandai M Kataoka 《Canadian Metallurgical Quarterly》1996,35(9):728-731
A 60-year-old man was admitted to our hospital for productive cough. Chest roentgenography and CT scan disclosed a left hilar tumor invading the mediastinum, with mediastinal lymphadenopathy and diffuse micronodular shadows in both lung fields. A biopsied sample of the tumor revealed squamous cell carcinoma, while noncaseating epithelioid cell granulomas were observed in the samples obtained by transbronchial lung biopsy. The granulomas in the pulmonary parenchyma were determined to be sarcoid reactions secondary to lung cancer, since there was no evidence of sarcoidosis. Combination chemotherapy was effective for the tumor, and the granulomas disappeared after completion of the chemotherapy. These findings suggest the presence of a relationship between sarcoid reactions and lung cancer in this case. 相似文献
89.
N Kawai M Sato T Sonomura K Kishi M Terada K Tanaka H Tanaka M Nosaka H Takata H Nakanishi A Yoshikawa 《Canadian Metallurgical Quarterly》1998,58(7):366-368
Percutaneous ethanol injection therapy (PEIT) is widely used as a local treatment for hepatocellular carcinoma (HCC). However, because only a small amount of ethanol can be used in one PEIT session and because the antitumor effect is limited, this modality is indicated only when there are three or fewer tumors and when the tumor diameter is < or = 3 cm. To obtain a more potent and certain antitumor effect, we have devised a new treatment called percutaneous hot ethanol injection therapy (PHEIT), and developed a Continuous Heating Device with which ethanol can be heated and locally injected at a specified temperature. The continuous Heating Device is composed of three major components: a syringe heater, a needle thermocontroller, and a needle tip thermosensor. A disposable syringe filled with liquid is inserted into the syringe heater, which heats the liquid to a desired temperature by adjusting the voltage. The needle thermocontroller is a puncture guide needle to which a heating device has been attached. The needle-tip thermosensor constantly measures, displays and records the temperature of the liquid at the needle tip during injection. Also, because the Continuous Heating Device is a closed-circuit system, there is no risk of accidental a fire, which ensures procedural safety. It is also possible to use this device to safely heat and inject a variety of other liquids, such as physiological saline and anticancer agents and thus contribute to the widespread development of ultrasound-guided injection therapy. 相似文献
90.
To realize closed loop manufacturing, it is essential to design product life cycles and to plan life cycle processes property. Life cycle simulation has been recognized as an effective tool in this direction. In this paper, we present a life cycle simulation system developed as a general tool for life cycle design and management. The system includes functions for modelling and controlling each life cycle process in a flexible manner. The system maintains usage history of products and parts independently taking the reuse of parts into account. Examples of the simulation are shown for both a rapid life cycle scenario and for a part sharing scenario over the product generations. 相似文献