全文获取类型
收费全文 | 1420篇 |
免费 | 10篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 12篇 |
综合类 | 1篇 |
化学工业 | 62篇 |
金属工艺 | 7篇 |
机械仪表 | 19篇 |
建筑科学 | 29篇 |
矿业工程 | 1篇 |
能源动力 | 13篇 |
轻工业 | 33篇 |
水利工程 | 4篇 |
石油天然气 | 1篇 |
无线电 | 153篇 |
一般工业技术 | 94篇 |
冶金工业 | 942篇 |
原子能技术 | 2篇 |
自动化技术 | 58篇 |
出版年
2022年 | 5篇 |
2021年 | 7篇 |
2018年 | 7篇 |
2017年 | 9篇 |
2016年 | 9篇 |
2014年 | 13篇 |
2013年 | 23篇 |
2012年 | 18篇 |
2011年 | 27篇 |
2010年 | 19篇 |
2009年 | 19篇 |
2008年 | 33篇 |
2007年 | 20篇 |
2006年 | 28篇 |
2005年 | 20篇 |
2004年 | 26篇 |
2003年 | 11篇 |
2002年 | 22篇 |
2001年 | 24篇 |
2000年 | 14篇 |
1999年 | 53篇 |
1998年 | 282篇 |
1997年 | 147篇 |
1996年 | 118篇 |
1995年 | 76篇 |
1994年 | 52篇 |
1993年 | 55篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1990年 | 13篇 |
1989年 | 21篇 |
1988年 | 11篇 |
1987年 | 10篇 |
1986年 | 14篇 |
1985年 | 10篇 |
1984年 | 7篇 |
1983年 | 6篇 |
1982年 | 12篇 |
1981年 | 14篇 |
1980年 | 14篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 24篇 |
1976年 | 53篇 |
1975年 | 6篇 |
1974年 | 9篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1971年 | 4篇 |
1966年 | 5篇 |
排序方式: 共有1431条查询结果,搜索用时 15 毫秒
61.
Blends of alcohol ethoxysulfates (AES) and alcohol ethoxylates (AE) at high active matter content (90%) have been prepared.
These blends contain no solvents other than water and have sufficiently low viscosities enabling the pumping of them from
storage vessels to mix tanks. In addition, they may be diluted into aqueous solutions with less gel formation tendencies than
shown by AE or AES alone. Specific AE/AES blend ratios, alkyl and polyoxyethylene chain lengths are important selection parameters
for achieving desired rheological properties.
This paper was presented at the 79th American Oil Chemists’ Society Annual Meeting, May 1988, Phoenix, Arizona. 相似文献
62.
Dynameomics: design of a computational lab workflow and scientific data repository for protein simulations 总被引:1,自引:0,他引:1
Simms AM Toofanny RD Kehl C Benson NC Daggett V 《Protein engineering, design & selection : PEDS》2008,21(6):369-377
Dynameomics is a project to investigate and catalog the native-state dynamics and thermal unfolding pathways of representatives of all protein folds using solvated molecular dynamics simulations, as described in the preceding paper. Here we introduce the design of the molecular dynamics data warehouse, a scalable, reliable repository that houses simulation data that vastly simplifies management and access. In the succeeding paper, we describe the development of a complementary multidimensional database. A single protein unfolding or native-state simulation can take weeks to months to complete, and produces gigabytes of coordinate and analysis data. Mining information from over 3000 completed simulations is complicated and time-consuming. Even the simplest queries involve writing intricate programs that must be built from low-level file system access primitives and include significant logic to correctly locate and parse data of interest. As a result, programs to answer questions that require data from hundreds of simulations are very difficult to write. Thus, organization and access to simulation data have been major obstacles to the discovery of new knowledge in the Dynameomics project. This repository is used internally and is the foundation of the Dynameomics portal site http://www.dynameomics.org. By organizing simulation data into a scalable, manageable and accessible form, we can begin to address substantial questions that move us closer to solving biomedical and bioengineering problems. 相似文献
63.
64.
E. P. G. Smith E. A. Patten P. M. Goetz G. M. Venzor J. A. Roth B. Z. Nosho J. D. Benson A. J. Stoltz J. B. Varesi J. E. Jensen S. M. Johnson W. A. Radford 《Journal of Electronic Materials》2006,35(6):1145-1152
High-performance 20-μm unit-cell two-color detectors using an n-p+-n HgCdTe triple-layer heterojunction (TLHJ) device architecture grown by molecular beam epitaxy (MBE) on (211)-oriented CdZnTe
substrates with midwavelength (MW) infrared and long wavelength (LW) infrared spectral bands have been demonstrated. Detectors
with nominal MW and LW cut-off wavelengths of 5.5 μm and 10.5 μm, respectively, exhibit 78 K LW performance with >70 % quantum
efficiency, reverse bias dark currents below 300 pA, and RA products (zero field of view, 150-mV bias) in excess of 1×103 Ωcm2. Temperature-dependent current-voltage (I–V) detector measurements show diffusion-limited LW dark current performance extending
to temperatures below 70 K with good operating bias stability (150 mV ± 50 mV). These results reflect the successful implementation
of MBE-grown TLHJ detector designs and the introduction of advanced photolithography techniques with inductively coupled plasma
(ICP) etching to achieve high aspect ratio mesa delineation of individual detector elements with benefits to detector performance.
These detector improvements complement the development of high operability large format 640×480 and 1280×720 two-color HgCdTe
infrared focal plane arrays (FPAs) to support third generation forward looking infrared (FLIR) systems. 相似文献
65.
66.
The severity of pulmonary fibrosis is the main prognostic factor for survival of patients with interstitial lung diseases (ILD). Unfortunately, lung biopsy, which is the best method to assess fibrosis quantitatively, is done only once during the evolution of the disease. In this study we analyzed the relationship between the degree of fibrosis and the exponential constant k, derived from the lung pressure-volume curve (LPVC) in 33 patients with chronic ILD, 19 with pigeon breeder's disease (PBD), and 14 with idiopathic pulmonary fibrosis (IPF). Pulmonary function tests, including the LPVC, were obtained before biopsy. A semiquantitative histologic assessment of the severity of fibrosis was performed on lung tissues. All patients showed a decrease of total lung capacity, residual volume, compliance, and Pao2. The mean value of the constant k was 0.08 +/- 0.06. When expressed as a percent of normal values, 25 patients exhibited values of k lower than 70% of predicted; of the remaining 8 patients whose values were above 70% of predicted, 7 had PBD and only one IPF. On morphologic analysis, 19 patients displayed more than 50% fibrosis. No significant correlations were found between the extent of the lesion or severity of lung fibrosis and the conventional pulmonary function tests. By contrast, a moderate but significant correlation was found between k and the severity of lung fibrosis (r = -0.38, p < 0.05). These findings show that the shape of the LPVC, represented by the constant k, predicts the degree of lung fibrosis and could be useful in the clinical assessment and follow-up of patients with ILD. 相似文献
67.
L Abbeduto K Short-Meyerson G Benson J Dolish M Weissman 《Canadian Metallurgical Quarterly》1998,41(6):1348-1362
Listeners interpret utterances against the common ground, or network of presuppositions shared with the speaker. The first purpose of the study was to determine whether individuals with mental retardation use the major sources of common ground (i.e., physical copresence, linguistic copresence, and community membership) to resolve referential ambiguity. The second purpose was to determine whether they seek confirmation of their referent choices in accordance with the certainty of interpretation afforded by the common ground. The third purpose was to determine whether they signal noncomprehension when faced with ambiguity and common ground that is not informative. The final purpose was to evaluate the relationship between within-group variability in common ground use and measures of nonverbal cognition, receptive and expressive language, and social cognition. Participants were school-age individuals with mental retardation and typically developing children matched to them on nonverbal MA. Common ground use was examined in a role-playing task in which the participant responded to ambiguous utterances. Common ground was manipulated within participants. We determined whether referent selections were appropriate for the common ground, whether they were accompanied by confirmation requests, and whether noncomprehension was signaled. Both groups used all sources of common ground to resolve referential ambiguity at better than chance levels but were less successful in using community membership. Both groups also requested confirmation of their referent choices most often when the common ground was based on community membership. Both groups signaled noncomprehension when the common ground was not informative. Different aspects of common ground use were related to different predictors for the group with mental retardation. 相似文献
68.
PJ Morrison S Macphail D Williams G McCusker P McKeever C Wright NC Nevin 《Canadian Metallurgical Quarterly》1998,18(9):963-967
Congenital atresia of the larynx is a rare abnormality. We describe three cases where prenatal diagnosis during the second trimester showed massive abdominal fetal ascites and at post-mortem, laryngeal atresia was identified in two cases, and severe laryngeal stenosis in the third. All were associated with pulmonary hyperplasia. No additional abnormalities were found in other systems. Overdistended lung tissue and ascites are resultant from aberrant laryngeal growth; laryngeal anomalies are a cause of isolated fetal ascites. The association of ascites and voluminous lungs should arouse suspicion of laryngeal atresia and should be an indication for careful pathological study of the fetal larynx. 相似文献
69.
SJ Benson BL Ruis AL Garbers AM Fadly KF Conklin 《Canadian Metallurgical Quarterly》1998,72(12):10301-10304
A new subgroup of avian leukosis virus (ALV) that includes a unique env gene, designated J, was identified recently in England. Sequence analysis of prototype English isolate HPRS-103 revealed several other unique genetic characteristics of this strain and provided information that it arose by recombination between exogenous and endogenous virus sequences. In the past several years, ALV J type viruses (ALV-J) have been isolated from broiler breeder flocks in the United States. We were interested in determining the relationship between the U.S. and English isolates of ALV-J. Based on sequence data from two independently derived U.S. field isolates, we conclude that the U.S. and English isolates of ALV-J derive from a common ancestor and are not the result of independent recombination events. 相似文献
70.
S Gupta DW Black S Arndt WC Hubbard NC Andreasen 《Canadian Metallurgical Quarterly》1998,49(10):1353-1355
This study explored the association between psychosocial variables and symptoms among patients with schizophrenia-spectrum disorders who have attempted suicide and those who have not attempted suicide. Of 336 patients with a DSM-III-R diagnosis of schizophrenia or schizoaffective disorder who were consecutively evaluated at a university-affiliated clinical research center, 98, or 29.2 percent, reported one or more suicide attempts. Compared with patients who had not attempted suicide, patients who had made an attempt had a greater number of lifetime depressive episodes, an earlier age of onset of their illness, and an earlier age at first hospitalization. 相似文献