全文获取类型
收费全文 | 687篇 |
免费 | 16篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 20篇 |
金属工艺 | 1篇 |
机械仪表 | 7篇 |
建筑科学 | 5篇 |
能源动力 | 3篇 |
轻工业 | 50篇 |
石油天然气 | 1篇 |
无线电 | 20篇 |
一般工业技术 | 58篇 |
冶金工业 | 512篇 |
原子能技术 | 3篇 |
自动化技术 | 20篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 9篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 2篇 |
2014年 | 12篇 |
2013年 | 22篇 |
2012年 | 14篇 |
2011年 | 6篇 |
2010年 | 9篇 |
2009年 | 7篇 |
2008年 | 5篇 |
2007年 | 6篇 |
2006年 | 9篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 4篇 |
1999年 | 9篇 |
1998年 | 147篇 |
1997年 | 89篇 |
1996年 | 75篇 |
1995年 | 44篇 |
1994年 | 29篇 |
1993年 | 25篇 |
1992年 | 8篇 |
1991年 | 6篇 |
1990年 | 10篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 10篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 25篇 |
1976年 | 39篇 |
1975年 | 5篇 |
1972年 | 1篇 |
1954年 | 1篇 |
1948年 | 2篇 |
排序方式: 共有703条查询结果,搜索用时 14 毫秒
11.
12.
13.
Laura Vázquez‐Araújo Edgar Chambers IV Panat Cherdchu 《Journal of food science》2012,77(10):S384-S389
Abstract: Because sorghum grain has important characteristics (for example, great antioxidant profile) for introduction into the regular human diet, producers and industry aim to develop successful products using sorghum as the base. The 1st step in developing products attractive for consumers is understanding consumer needs and expectations. Conjoint analysis determines attributes which may be important or unimportant for one product. In this study, focus groups and conjoint analysis were used to establish which attributes are helpful for promoting purchase intent of sorghum grain products. Once those characteristics were chosen, a national survey was conducted to confirm the selection. During the focus groups, the heath aspects of grain products seemed to be the most appealing for consumers, whereas conjoint analysis showed that sensory attributes were the principal drivers for purchase intent. Practical Application: The data presented in this study are essential for industry as a starting point for developing sorghum grain based food products. It is necessary to address consumers’ demands to ensure new products’ success in the market, and the present study clearly shows this consumers’ input. 相似文献
14.
Literature data are reviewed concerning morphological and morphogenetic features of stomach ulcer, vascular alterations in both the ulcer zone and other regions of the stomach. Stages in ulcer formation, its healing and prognostic criteria are described. Further study of ulcerogenesis regarding histotopographic features of different regions of gastro-intestinal tract is recommended. 相似文献
15.
16.
OBJECTIVES: As the incidence of prostate cancer in the United States exceeds 330,000 in 1997, increasingly more men are faced with treatment choices for which there is no clear approach. At every stage of disease, these treatment choices may involve clinically equivalent modalities that differ in side effects and impact upon quality of life (QOL). Comprehensive, yet efficient, questionnaires are needed to measure QOL in patients with prostate cancer. METHODS: Developed as a disease-specific adjunct to the Functional Assessment of Cancer Therapy (FACT) measurement system, a 12-item prostate cancer subscale (PCS) was developed and tested in three independent samples: a subscale development sample (n = 43), validity sample 1 (n = 34), and validity sample 2 (n = 96). The 12 items ask about symptoms and problems specific to prostate cancer. These questions are added to the general (FACT-G) instrument, thereby comprising a 47-item questionnaire. RESULTS: Internal consistency of the PCS ranged from 0.65 to 0.69, with coefficients for FACT-G subscales and aggregated scores ranging from 0.61 to 0.90. Concurrent validity was confirmed by the ability to discriminate patients by disease stage, performance status, and baseline prostate-specific antigen (PSA) level. Sensitivity to change in performance status and PSA score over a 2-month period suggested that some subscales of the FACT-Prostate (P) (including the PCS) are sensitive to meaningful clinical change. CONCLUSIONS: Our findings support use of the FACT-P as a meaningful component of QOL evaluation in men undergoing therapy for prostate cancer. 相似文献
17.
Monoterpenes such as limonene and perillyl alcohol (PA) are currently under investigation for their chemotherapeutic properties which have been tied to their ability to affect protein isoprenylation. Because PA affects the synthesis of isoprenoids’ such as ubiquinone’ and cholesterol is the end product of the synthetic pathway from which this isoprenoid pathway branches’ we investigated the effects of this compound upon cholesterol metabolism in the colonic adenocarcinoma cell line SW480. PA (1 mM) inhibited incorporation of 14C-mevalonate into 21–26 kDa proteins by 25% in SW480 cells. Cholesterol (CH) biosynthesis was assessed by measuring the incorporation of 14C-acetate and 14C-mevalonate into 27-carbon-sterols. Cells treated with PA (1 mM) exhibited a fourfold increase in the incorporation of 14C-acetate but not 14C-mevalonate into cholesterol. Mevinolin (lovastatin)’ an inhibitor of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase’ at 2 μM concentration’ inhibited CH synthesis from 14C-acetate by 80%. Surprisingly’ concurrent addition of mevinolin and PA did not significantly alter the stimulatory effects of PA. As observed differences in 14C-acetate and 14C-mevalonate precursor labeling could indicate PA affects early pathway events’ the effects of this monoterpene on HMG-CoA reductase activity were evaluated. Unexpectedly’ 1 mM PA did not stimulate activity of this enzyme. Consistent with its action as a reversibly bound inhibitor’ in washed microsomes’ 2 μM mevinolin pretreatment increased reductase protein expression causing a 12.7 (±2.4)-fold compensatory HMG-CoA reductase activity increase; concurrent treatment with 1 mM PA attenuated this to a 5.3 (±0.03)-fold increase. Gas chromatographic analysis confirmed CH was the major lipid present in the measured thin-layer chromatography spot. Since 14C-acetate incorporation into free fatty acid and phospholipid pools was not significantly affected by PA treatment’ nonspecific changes in whole acetate pool sizes were not indicated. Because increases in endogenous CH synthesis should result in compensatory changes in exogenous sterol utilization’ the effects of PA upon low density lipoprotein (LDL) receptor activity were evaluated. Consistent with the observed increases in CH synthesis’ 1 mM PA decreased 125I-LDL internalization to 50% of the fetal bovine serum control; concurrent addition of 2 μM mevinolin attenuated this effect to a reduction of 80% of the control value. Data suggest that in certain colonic tumor cells PA strongly affects cholesterol metabolism via a mechanism of action that is insensitive to the HMG-CoA reductase inhibitor mevinolin. 相似文献
18.
The quantity, extraction efficiency, and molecular composition of non-volatile oligomeric species in SOA generated by the reaction of α-pinene with ozone were studied. Two different methods of determining the total particulate mass in the reaction chamber were compared and found to be in good agreement when changes in the partitioning of semi-volatile compounds to the particle phase during measurement were properly handled. Almost all of the non-volatile organic carbon formed by the reaction was collected and recovered by extraction with organic solvents; recoveries with water extraction were somewhat lower. The identities of compounds extracted by the various solvents were determined using electrospray ionization Fourier transform ion cyclotron resonance (ESI-FTICR) mass spectrometry. Over 80% of the peaks weighted by mass and intensity were the same in the spectra of samples obtained from different extraction solvents. Standard addition plots were used to determine the amounts of two commercially available monomer compounds in the SOA extracts. When the response factors for those compounds were applied to other monomers detected in the mass spectra, the weight percent of monomers was estimated to be slightly less than 50%, with the remaining mass (over 50%) assigned to oligomers. The oligomer content is sufficiently large that it should be taken into account when modeling the formation and properties of laboratory SOA. 相似文献
19.
Abstract The height equivalent to a theoretical stage (HETS) is estimated using one correlation to describe behavior for reciprocating speeds below the optimum point and a second expression to estimate HETS values for reciprocating speeds above it. These two equations are then combined to yield a generalized expression that is applicable in both regions and which can be used to predict the minimum HETS and the optimum reciprocating speed. The observed dependence on the operating parameters and the physical properties of the liquid/liquid system generally agree with those observed in HETS correlations for pulse columns. 相似文献
20.
The use of complex materials, such as composites, for fabrication of structural components exacts a price of increased complexity in design and analysis of these structures. In order to economically and efficiently facilitate complex structural design and analysis, computer-aided design techniques are being employed throughout the industrial community. This paper illustrates a system of computer-aided design techniques and software (CADOT) for the design and analysis of engineering structures and solids that are constructed of sheet molding, injection molding, and/or laminated composite technologies. 相似文献