全文获取类型
收费全文 | 1143篇 |
免费 | 12篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 34篇 |
化学工业 | 145篇 |
金属工艺 | 15篇 |
机械仪表 | 15篇 |
建筑科学 | 7篇 |
能源动力 | 48篇 |
轻工业 | 98篇 |
水利工程 | 1篇 |
无线电 | 134篇 |
一般工业技术 | 208篇 |
冶金工业 | 368篇 |
原子能技术 | 19篇 |
自动化技术 | 64篇 |
出版年
2022年 | 7篇 |
2021年 | 4篇 |
2019年 | 5篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 6篇 |
2015年 | 3篇 |
2014年 | 8篇 |
2013年 | 31篇 |
2012年 | 33篇 |
2011年 | 32篇 |
2010年 | 26篇 |
2009年 | 22篇 |
2008年 | 27篇 |
2007年 | 35篇 |
2006年 | 30篇 |
2005年 | 27篇 |
2004年 | 28篇 |
2003年 | 39篇 |
2002年 | 23篇 |
2001年 | 37篇 |
2000年 | 27篇 |
1999年 | 26篇 |
1998年 | 134篇 |
1997年 | 71篇 |
1996年 | 66篇 |
1995年 | 41篇 |
1994年 | 36篇 |
1993年 | 44篇 |
1992年 | 22篇 |
1991年 | 22篇 |
1990年 | 20篇 |
1989年 | 14篇 |
1988年 | 17篇 |
1987年 | 11篇 |
1986年 | 18篇 |
1985年 | 19篇 |
1984年 | 15篇 |
1983年 | 15篇 |
1982年 | 16篇 |
1981年 | 14篇 |
1980年 | 6篇 |
1979年 | 5篇 |
1978年 | 10篇 |
1977年 | 15篇 |
1976年 | 16篇 |
1975年 | 3篇 |
1974年 | 5篇 |
1972年 | 3篇 |
1967年 | 2篇 |
排序方式: 共有1156条查询结果,搜索用时 78 毫秒
61.
62.
Remnants of chylomicron and very low density lipoprotein impair endothelium-dependent vasorelaxation
H Doi K Kugiyama M Ohgushi S Sugiyama T Matsumura Y Ohta T Nakano K Nakajima H Yasue 《Canadian Metallurgical Quarterly》1998,137(2):341-349
Given the multiple impairments in host defense that occur during HIV infection, patients with AIDS are at risk for a variety of pleural infections and neoplasms. Of infectious causes, bacterial parapneumonic effusions and empyemas and tuberculous pleurisy occur more frequently than effusions caused by P. carinii. In each case, therapy is directed at eradication of the causative organisms. In the setting of systemic Kaposi's sarcoma, pleural involvement is common, although diagnosis is difficult and therapeutic options are limited. Pleural effusions caused by non-Hodgkin's lymphoma often occur in the setting of pulmonary parenchymal disease and can be diagnosed cytologically. The recently described entity of primary effusion lymphoma occurs in the absence of solid-organ involvement. The development of a spontaneous pneumothorax in a HIV-infected individual should prompt a search for P. carinii infection. Although these pneumothoraces often recur and are difficult to manage, recent series suggest that surgical approaches to bronchopleural fistulas are reasonable in selected patients. 相似文献
63.
In order to investigate the relationship between various temporomandibular joint (TMJ) pain levels and the detection of high signal intensity (joint effusion) on T2 weighted magnetic resonance imaging (MRI), 19 consecutive patients who complained of unilateral painful TMJ hypomobility (closed locking) were involved in this study. All patients were clinically examined in a routine manner, and all patients rated their pain levels by a visual analogue scale and eight pain questionnaire prior MRI study. T1 and T2 weighted MRI was taken in sagittal section at unilateral affected joint side. The presence or absence of a high signal intensity spot within the TMJ compartment were judged by three examiners. The high signal intensity was detected in 10 joints, but not in 9 joints. In between these two groups, the pain ratio was calculated and compared. The data showed that there was no significant statistical correlation between pain levels and the presence of high signals. This study disclosed that the MRI detection of high signal intensity in the closed locking TMJ did not directly relate to the presence of TMJ pain nor the increased pain level. These indicate the need of further larger studies. 相似文献
64.
65.
T Yamazaki T Kimoto K Higuchi Y Ohta S Kawato S Kominami 《Canadian Metallurgical Quarterly》1998,139(12):4765-4771
o-Nitrophenyl sulfenyl-modified ACTH (NPS-ACTH) stimulated steroidogenesis acutely in bovine fasciculata-reticularis cells without increase in cellular cAMP synthesis. Application of NPS-ACTH to the cultured cells induced Ca2+ signals in individual cells as detected by video-enhanced microscopic fluorescence measurements. The percentage of Ca2+ signaling cells corresponded well with the increase of steroidogenesis induced by NPS-ACTH below 1 nM. Treatment of the cells with nicardipine, a Ca2+ channel blocker, suppressed the Ca2+ signals except for the transient increase just after the addition of NPS-ACTH and also blocked completely the stimulative effect on the steroidogenesis of NPS-ACTH below 1 nM. At a dosage of NPS-ACTH higher than 10 nM, the stimulative effect of steroidogenesis was partly suppressed by nicardipine and also by AA-861, a lipoxygenase inhibitor. The action of NPS-ACTH might be mediated by both Ca2+ and lipoxygenase metabolite(s) of arachidonic acid as dual second messengers. The effect of ACTH in pM range on the steroidogenesis was suppressed completely by the treatment with nicardipine and AA-861 at the same time, indicating that the action was mediated by both Ca2+ and the lipoxygenase metabolite(s) but not by cAMP. cAMP plays a significant role as a second messenger for ACTH action only at ACTH concentrations greater than 10 pM. 相似文献
66.
K Ohta 《Canadian Metallurgical Quarterly》1996,54(11):2908-2913
It is important to determine what kind of antigen is involved in atopic asthma for appropriate management as well as diagnosis. We can measure total IgE and antigen specific IgE antibodies by means of RIA and EIA in vitro. Antigen specific IgE antibodies can be detected more sensitively by skin tests consisting of intradermal, prick and scratch tests, among which the intradermal test is most sensitive. To study if the antibody thus detected is functional, there are in vivo tests such as the provocation test and eye reaction with the corresponding antigen and in vitro tests such as the histamine release assay and CAST. In Japan we tend to prefer in vitro assays, while the skin test has been recommended more than in vitro assays in the United States. 相似文献
67.
The properties of high-field domains in GaxIn1-xSb Gunn diodes (0.4 < x < 0.82) have been studied by measuring the surface potential on the diodes. The domain velocities vary with the Ga composition x, 5.3?6.1×106 cm/s for0.8 > x > 0.55 and 10×106 cm/s for x = 0.4, but they are almost independent of the applied voltage, even if the electron concentration is increased by the impact ionisation in the domain at high applied voltages for the small-x samples. 相似文献
68.
Comparison between a petroleum energy system and a solar-hydrogen energy system is studied in the case where an industry is newly introduced to an isolated island. Assuming a hybrid energy system composed of petroleum, solar energy, hydrogen energy and electric energy, we investigate an optimum economy with the use of computer-aided LP (Linear Programming) and QP (Quadratic Programming) models taking account of the cost functions originated from the acquisition prices of the primary energy and the transport prices. Furthermore, the modified LP model makes it possible to take account of the uncertainties arising from the acquisition instability and environmental protection. Some conditions are clarified under which the introduction of a solar-hydrogen energy system is highly feasible. 相似文献
69.
Summary The chlorine in poly(epichlorohydrin) was found to be substituted by diethyldithiocarbamate (ETC) group by the reaction with NaETC in tetrahydrofuran at 60°C. The reaction product was analyzed by RI-UV dual-detector GPC. The composition i.e. the percentage of the chlorine replaced by the ETC group was found to be invariant with the elution count. This result might indicate the absence of polymer effect in the carbamation of poly(epichlorohydrin). 相似文献
70.
Koichi Hatada Tatsuki Kitayama Kinzo Fujikawa Koji Ohta Heimei Yuki 《Polymer Bulletin》1978,1(2):97-102
Summary Copolymer of methyl methacrylate-d8(M1) with a small amount of trityl methacrylate(M2) was radically prepared in tetrahydrofuran and converted into the copolymer of methyl methacrylate-d8 with a small amount of undeuterated methyl methacrylate by the selective hydrolysis of the trityl group and subsequent methylation with diazomethane. From the 1H NMR spectrum of the derived copolymer the assigned coisotactic parameters 12 and 21 were determined to be 0.14 and 0.61, respectively. This may be the first example of the unequivocal determination of assigned configurational parameters in cross propagation for copolymerization. 相似文献