全文获取类型
收费全文 | 4211篇 |
免费 | 110篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 31篇 |
综合类 | 8篇 |
化学工业 | 652篇 |
金属工艺 | 40篇 |
机械仪表 | 45篇 |
建筑科学 | 117篇 |
矿业工程 | 6篇 |
能源动力 | 69篇 |
轻工业 | 201篇 |
水利工程 | 20篇 |
石油天然气 | 8篇 |
无线电 | 182篇 |
一般工业技术 | 383篇 |
冶金工业 | 2183篇 |
原子能技术 | 20篇 |
自动化技术 | 361篇 |
出版年
2023年 | 27篇 |
2022年 | 35篇 |
2021年 | 44篇 |
2020年 | 35篇 |
2019年 | 46篇 |
2018年 | 52篇 |
2017年 | 52篇 |
2016年 | 72篇 |
2015年 | 68篇 |
2014年 | 83篇 |
2013年 | 119篇 |
2012年 | 102篇 |
2011年 | 146篇 |
2010年 | 106篇 |
2009年 | 96篇 |
2008年 | 113篇 |
2007年 | 103篇 |
2006年 | 78篇 |
2005年 | 79篇 |
2004年 | 59篇 |
2003年 | 71篇 |
2002年 | 50篇 |
2001年 | 37篇 |
2000年 | 34篇 |
1999年 | 119篇 |
1998年 | 709篇 |
1997年 | 387篇 |
1996年 | 260篇 |
1995年 | 174篇 |
1994年 | 142篇 |
1993年 | 140篇 |
1992年 | 33篇 |
1991年 | 36篇 |
1990年 | 35篇 |
1989年 | 42篇 |
1988年 | 31篇 |
1987年 | 37篇 |
1986年 | 39篇 |
1985年 | 41篇 |
1984年 | 18篇 |
1983年 | 15篇 |
1982年 | 16篇 |
1981年 | 26篇 |
1980年 | 26篇 |
1979年 | 12篇 |
1978年 | 21篇 |
1977年 | 70篇 |
1976年 | 108篇 |
1975年 | 11篇 |
1974年 | 12篇 |
排序方式: 共有4326条查询结果,搜索用时 15 毫秒
21.
22.
S Hunt Gerardo DM Citron MC Claros EJ Goldstein 《Canadian Metallurgical Quarterly》1996,40(10):2413-2415
When the Etest was compared to broth microdilution for susceptibility testing of Streptococcus pneumoniae, levofloxacin, erythromycin, and penicillin results correlated for both methods; azithromycin and clarithromycin showed discrepancies of > or = 2 dilutions for 95.8% and 31.5% of the isolates, respectively. Levofloxacin was active against 141 of 142 isolates (< or = 2.0 micrograms/ml), making it a potentially useful new fluoroquinolone. 相似文献
23.
Although European treatises were translated and available to American doctors interested in neurology during the 19th century, the early American neurologic textbooks were distinctive in their comprehensive integration of basic and clinical science. William A. Hammond, in 1871, published the first comprehensive American textbook of neurology, preceding the manuals by Gowers (1886) and Oppenheim (1894) by more than a decade. Four other American adult neurologic textbooks expanded on Hammond's model and incorporated other important topics, including neurologic anatomy, the formal examination, neurochemistry, and complete bibliographies. Bernard Sachs' 1895 textbook was the first pediatric neurologic textbook published in America and made significant contributions to the organization of childhood neurologic disorders. These works functioned as centralized resources for neurologic information, were influential educational tools, and helped foster a growing appreciation of the American neurologic school both nationally and internationally. 相似文献
24.
25.
EJ Henriksen S Jacob DL Fogt EB Youngblood J G?dicke 《Canadian Metallurgical Quarterly》1997,30(6):1560-1565
The sympatholytic antihypertensive agent moxonidine, a centrally acting selective I1-imidazoline receptor modulator (putative agonist), may be beneficial in hypertensive patients with insulin resistance. In the present study, the effects of chronic in vivo moxonidine treatment of obese Zucker rats--a model of severe glucose intolerance, hyperinsulinemia and insulin resistance, and dyslipidemia--on whole-body glucose tolerance, plasma lipids, and insulin-stimulated skeletal muscle glucose transport activity (2-deoxyglucose uptake) were investigated. Moxonidine was administered by gavage for 21 consecutive days at 2, 6, or 10 mg/kg body weight. Body weights in control and moxonidine-treated groups were matched, except at the highest dose, at which final body weight was 17% lower in the moxonidine-treated animals compared with controls. The moxonidine-treated (6 and 10 mg/kg) obese animals had significantly lower fasting plasma levels of insulin (17% and 19%, respectively) and free fatty acids (36% and 28%, respectively), whereas plasma glucose was not altered. During an oral glucose tolerance test, the glucose response (area under the curve) was 47% and 67% lower, respectively, in the two highest moxonidine-treated obese groups. Moreover, glucose transport activity in the isolated epitrochlearis muscle stimulated by a maximally effective insulin dose (13.3 nmol/L) was 39% and 70% greater in the 6 and 10 mg/kg moxonidine-treated groups, respectively (P<.05 for all effects). No significant alterations in muscle glucose transport were elicited by 2 mg/kg moxonidine. These findings indicate that in the severely insulin-resistant and dyslipidemic obese Zucker rat, chronic in vivo treatment with moxonidine can significantly improve, in a dose-dependent manner, whole-body glucose tolerance, possibly as a result of enhanced insulin-stimulated skeletal muscle glucose transport activity and reduced circulating free fatty acids. 相似文献
26.
27.
Reliability aspects of microsensors and micromechatronic actuators for automotive applications 总被引:1,自引:0,他引:1
In modern cars microsensors and micromechatronic actuators play an essential and still increasingly important role as the interface between the vehicle with its complex functions of motor management, chassis systems, safety as well as comfort and convenience on the one hand and the respective electronic control units on the other hand. They have to fulfill their task in a harsh environment over the entire lifetime of an automobile. Therefore reliability aspects have moved more and more into the focus of engineering and research activities in microsystem technology. A methodical procedure is described that allows reliability issues to be approached efficiently. The implementation of the methodology is illustrated with real-life examples of reliability aspects of hot film mass air flow sensors, inertial sensors as well as piezoelectric actuators. 相似文献
28.
This paper is the first part of a work devoted to the setting-up of a methodology for the mechanical behaviour characterization of rubber-like materials, using a digital speckle extensometer. We present here the experimental approach, specific to large strain measurements. The proposed method is based on in-plane kinematics measurements using an optical extensometer. The whole two-dimensional field of in-plane displacements is obtained by a digital image processing. We discuss then the correlation calculations and how to achieve the optimal subset matching. Next, we specify how to derive the principal stretch ratios, and the accuracy on these components, issued from a subsequent numerical calibration.Finally, we present experimental data dealing with a carbon black, filled natural rubber, issued from uniaxial traction tests, pure shear tests, and tensile tests performed on double-edge notched tensile specimens. 相似文献
29.
The Wabash River Integrated Methanol and Power Production from Clean Coal Technologies (IMPPCCT) project is investigating an Early Entrance Coproduction Plant (EECP) concept to evaluate integrated electrical power generation and methanol production from coal and other carbonaceous feedstocks. Research, development and testing (RD&T) that is currently being conducted under the project is evaluating cost effective process systems for removing contaminants, particularly sulfur species, from the generated gas which contains mainly synthesis gas (syngas), CO2 and steam at concentrations acceptable for the methanol synthesis catalyst. The RD&T includes laboratory testing followed by bench-scale and field testing at the SG Solutions Gasification Plant located in West Terre Haute, Indiana. Actual synthesis gas produced by the plant was utilized at system pressure and temperature for bench-scale field testing. 相似文献
30.
Problems that arise from health-care management, rather than from a disease process, are now recognized as making a substantial contribution to patient morbidity and mortality and to the cost of health care. However, most classifications of these problems do not provide sufficient detail to allow comparisons or to develop better strategies for the prevention, detection and management of these problems. A 'Generic Occurrence Classification' was developed to record their salient features, place them in context and elicit any system or human error-based contributing factors. This was done by an iterative process in which 'natural categories', identified from over 2000 incidents and 800 adverse events, were placed in a hierarchical structure created using software written in Microsoft Visual Basic; data were stored in a Microsoft Access database. This was shown to be a valid and reliable way to compare incidents and accidents from different sources and to allow sufficient detail to be retrieved to develop preventive strategies. 相似文献