全文获取类型
收费全文 | 7375篇 |
免费 | 222篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 94篇 |
综合类 | 1篇 |
化学工业 | 1217篇 |
金属工艺 | 120篇 |
机械仪表 | 214篇 |
建筑科学 | 276篇 |
矿业工程 | 20篇 |
能源动力 | 289篇 |
轻工业 | 598篇 |
水利工程 | 95篇 |
石油天然气 | 30篇 |
武器工业 | 2篇 |
无线电 | 571篇 |
一般工业技术 | 1229篇 |
冶金工业 | 1881篇 |
原子能技术 | 45篇 |
自动化技术 | 921篇 |
出版年
2022年 | 59篇 |
2021年 | 91篇 |
2020年 | 78篇 |
2019年 | 95篇 |
2018年 | 98篇 |
2017年 | 100篇 |
2016年 | 121篇 |
2015年 | 101篇 |
2014年 | 140篇 |
2013年 | 335篇 |
2012年 | 281篇 |
2011年 | 468篇 |
2010年 | 366篇 |
2009年 | 281篇 |
2008年 | 386篇 |
2007年 | 377篇 |
2006年 | 320篇 |
2005年 | 300篇 |
2004年 | 243篇 |
2003年 | 241篇 |
2002年 | 253篇 |
2001年 | 139篇 |
2000年 | 130篇 |
1999年 | 137篇 |
1998年 | 320篇 |
1997年 | 227篇 |
1996年 | 184篇 |
1995年 | 153篇 |
1994年 | 139篇 |
1993年 | 132篇 |
1992年 | 92篇 |
1991年 | 59篇 |
1990年 | 78篇 |
1989年 | 71篇 |
1988年 | 64篇 |
1987年 | 56篇 |
1986年 | 88篇 |
1985年 | 68篇 |
1984年 | 58篇 |
1983年 | 53篇 |
1982年 | 49篇 |
1981年 | 45篇 |
1980年 | 45篇 |
1979年 | 37篇 |
1978年 | 44篇 |
1977年 | 66篇 |
1976年 | 69篇 |
1975年 | 40篇 |
1974年 | 32篇 |
1972年 | 31篇 |
排序方式: 共有7603条查询结果,搜索用时 15 毫秒
11.
DL Scott 《Canadian Metallurgical Quarterly》1993,20(3):582-584
Changes in clinical and laboratory measures of disease activity were studied prospectively in 12 European centers. Altogether 282 rheumatoid patients were evaluated during 6 months of therapy with slow-acting drugs. Patients' global assessment was taken to indicate overall response. The number of swollen joints and number of tender joints correlated highly with this. The erythrocyte sedimentation rate (ESR) correlated less well but was more uniform across centers. Grip strength, C-reactive protein and hemoglobin performed poorly between centers. There were cultural and linguistic difficulties using the Health Assessment Questionnaire in a European setting. Physician's global assessments were similar to the patient's global assessments and provided redundant information. The best measures are: the number of swollen joints, the number of tender joints, the ESR, and the patient's global assessment. It may also help to measure articular pain. 相似文献
12.
L.D. Bozano B.W. Kean M. Beinhoff K.R. Carter P.M. Rice J.C. Scott 《Advanced functional materials》2005,15(12):1933-1939
Non‐volatile solid‐state memory cells based on composites of metal nanoparticles and polymers are embedded in organic semiconducting host materials. This paper presents data from a wide range of materials and device structures and shows that the switching phenomenon is commonly observed. 相似文献
13.
Howard George S.; Maxwell Scott E.; Berra Susan M.; Sternitzke Mary E. 《Canadian Metallurgical Quarterly》1985,70(1):233
Updated the report of W. M. Cox and V. Catt (see record 1978-21651-001) by determining the 40 top contributing institutions to the Journal of Applied Psychology, 1976–1982, and assessed the generalizability of productivity rankings based solely on contributions to this journal. A number of industrial and organizational psychologists were asked to indicate all the journals in which psychologists in the field were likely to publish. Five journals suggested by these nominators were used for comparison in the review. A list of the 40 most productive graduate programs based on these 5 journals is included. Results show the inadequacy of Cox and Catt's decision to base productivity ratings solely on contributions to 1 journal. Using 5 journals, 4 programs were catapulted into the top 10 rankings, while 7 programs dropped from top rankings in the Cox study (1970–1975) to below the 65th rank in the present study. Using only the Journal of Applied Psychology contributions, 2 of these programs ranked in the top 10, 1976–1982. (5 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
14.
The current, most frequently employed, commercial route to produce hydroxyapatite prosthetic coatings is plasma spraying. However, this has several important limitations especially for textured surfaces. Low temperature methods of coating fabrication such as cathodic electrodeposition are attractive alternatives. However, quantitative characterisation of the phase composition of thin electrodeposited coatings can be problematic. An X-ray diffraction method, which provides quantitative compositional information without reference to external or internal standards, is introduced and validated. The method can also be applied when Bragg peaks from the supporting substrate are apparent within the data and preferred orientation can be tolerated. This method has been used to examine in detail the microstructure of electrodeposited coatings which are compared directly with those formed by a commercial plasma spraying process.We show that, unlike the plasma sprayed coatings, the electrodeposited material consists of a single crystalline phase (hydroxyapatite) and a significantly reduced amorphous phase. The electrodeposited coatings also possess significantly more microstrain and a smaller crystallite size than the corresponding plasma sprayed material. 相似文献
15.
A 10.6 μm scan laser has been constructed and operated with an off-axis cathode ray tube, high reflectance multilayer thin-film structures, and a tapered plasma discharge tube. Equations are given for the switching time of a high-reflectance spot on the VO2 and for the relation of scan laser output power to cavity geometry, cavity losses, and the gain of the active CO2 medium. A scan capability of2.1 times 10^{3} easily resolvable directions was demonstrated, and sequential and randomly addressed spot rates of 105/s were achieved. The equations relating output power and cavity mode size were experimentally verified using a nonscanned beam. 相似文献
16.
17.
通神学是西方社会科学发展的产物.当科学和人们信仰的宗教产生冲突时,人们的精神该何去何从?最终,人们的精神从通神学那里获得了安宁.本文通过研究通神学的产生,以及它对艺术,包括建筑艺术的影响,探索当代建筑的本原和发展方向--表达情感、激起情感. 相似文献
18.
19.
In this report, we describe the nature of intermediate order in silicon as determined by recent measurements on thin films using transmission electron microscopy (TEM) and Raman scattering. The TEM images show in addition to the expected continuous random network (CRN), the presence of highly ordered quasi-one-dimensional “chain-like objects” (CLO's) that are 1–2 nm wide and tens of nm long that meander and show some evidence of cross-linking with each other. The presence of these objects correlate to a Raman feature centered at 490 cm−1 whose width is 35–40 cm−1, and is used to quantify the heterogeneity in terms of the CLO and CRN (=475 cm−1 scattering) concentrations. The 490 and 35 cm−1 values are consistent with bond angle deviations approaching 0°, and thus reinforces an association with the CLOs. We find that in reference quality a-Si:H (made using pure SiH4), the CLO concentration is about 5 vol%, while in state-of-the-art material using high H2 levels of dilution during processing, it increases to about 15%. Increased stability of such material to light-soaking is thus not mediated by a direct volumetric replacement of poor with high-quality components. Rather, an important characteristic of intermediate order in silicon is the low-dimensional aspect of its order, which allows it to influence more total volume than which it is itself composed. Consistent with these and other recent findings, we propose a tensegrity model of amorphous silicon. 相似文献
20.
Uses principles of latent trait theory to derive conditions under which mean differences on an observed variable are indicative of mean differences on an underlying construct, focusing on the logistic curve as a model for describing the relation between the observed variable and construct. In this situation, and with normally distributed scores on the construct, a t test comparing groups on the observed variable produces correct inferences at the construct level only if group variances on the construct are homogeneous or the difficulty level of the test equals the mean ability level of the examinees. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献