全文获取类型
收费全文 | 802篇 |
免费 | 3篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 26篇 |
金属工艺 | 13篇 |
机械仪表 | 3篇 |
建筑科学 | 7篇 |
矿业工程 | 1篇 |
能源动力 | 1篇 |
轻工业 | 7篇 |
水利工程 | 2篇 |
无线电 | 17篇 |
一般工业技术 | 36篇 |
冶金工业 | 672篇 |
自动化技术 | 19篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 2篇 |
2020年 | 4篇 |
2019年 | 4篇 |
2017年 | 1篇 |
2016年 | 2篇 |
2015年 | 4篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 7篇 |
2011年 | 6篇 |
2010年 | 5篇 |
2009年 | 9篇 |
2008年 | 7篇 |
2007年 | 8篇 |
2006年 | 7篇 |
2005年 | 11篇 |
2004年 | 4篇 |
2003年 | 7篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 22篇 |
1998年 | 186篇 |
1997年 | 118篇 |
1996年 | 79篇 |
1995年 | 53篇 |
1994年 | 30篇 |
1993年 | 37篇 |
1992年 | 6篇 |
1991年 | 7篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 4篇 |
1986年 | 6篇 |
1985年 | 5篇 |
1984年 | 1篇 |
1982年 | 7篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1978年 | 2篇 |
1977年 | 21篇 |
1976年 | 62篇 |
1975年 | 3篇 |
1956年 | 2篇 |
排序方式: 共有805条查询结果,搜索用时 0 毫秒
21.
To evaluate the utility of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) as a cancer therapeutic, we created leucine zipper (LZ) forms of human (hu) and murine (mu) TRAIL to promote and stabilize the formation of trimers. Both were biologically active, inducing apoptosis of both human and murine target cells in vitro with similar specific activities. In contrast to the fulminant hepatotoxicity of LZ-huCD95L in vivo, administration of either LZ-huTRAIL or LZ-muTRAIL did not seem toxic to normal tissues of mice. Finally, repeated treatments with LZ-huTRAIL actively suppressed growth of the TRAIL-sensitive human mammary adenocarcinoma cell line MDA-231 in CB.17 (SCID) mice, and histologic examination of tumors from SCID mice treated with LZ-huTRAIL demonstrated clear areas of apoptotic necrosis within 9-12 hours of injection. 相似文献
22.
23.
This research derives and tests hypotheses from two alternative conceptual models: the modified extended family model, and the changing family constraints model, which takes into account recent changes in work and family life. The hypotheses address social class differences in geographic distance and contact frequency between middle-aged children and their parents over time. Simultaneous probit models are used to analyze distance and contact as jointly determined outcomes with data from the USC Longitudinal Study of Generations and Mental Health. Results from these analyses indicate that children's 1971 educational aspirations and social class positions predict 1991 distance and contact between generations. Parents who have lower 1991 incomes, however, live farther from children and talk with them on the telephone less frequently than higher-income parents. Thus, the effects of early social class position support the modified extended family model, whereas the effects of current social class position support the changing family constraints model. 相似文献
24.
25.
OBJECTIVE: Cholelithiasis is a common problem in hospitals of the Peruvian Andes; however, its prevalence in Andean communities is unknown. To estimate the prevalence of gallstone disease in this locale, we conducted a cross-sectional community study in three high-altitude Peruvian rural villages (i.e., > 3000 m above sea level). METHODS: We examined 911 volunteers > 15 yr of age from three villages for gallstone disease by history and ultrasonography. Risk factors for gallstone disease were examined in 382 volunteers from one village. RESULTS: The age-adjusted prevalence of gallstone disease ranged from 4-10% in men and from 18-20% in women. Women had significantly higher age-adjusted prevalence rates than did men. The prevalence of gallstone disease increased significantly with age and decreased significantly with alcohol consumption. Although not statistically significant, we found a positive association between gallstone disease and body mass index. CONCLUSION: The results of this study indicate that gallstone disease, commonly perceived as a disease of the developed world, is also a common problem in high-altitude Peruvian communities. 相似文献
26.
NN Ninkina EM Privalova LG Pin?n AM Davies VL Buchman 《Canadian Metallurgical Quarterly》1999,246(2):308-311
Synucleins constitute a group of unique, evolutionarily conserved proteins that are expressed predominantly in neurons of the central and peripheral nervous system. Although the normal cellular functions of synucleins are not clear, these proteins have been implicated in various neurodegenerative conditions in humans. We found that persyn, a recently characterized member of the synuclein family, is expressed not only in the nervous system but also in the stratum granulosum of the epidermis of neonatal and adult mice. This finding together with our recent observations that persyn influences neurofilament network integrity in sensory neurons raises the possibility that persyn in skin could be involved in modulation of the keratin network. 相似文献
27.
SG Willis KS Smith VL Dunn LA Gapter KH Riviere GR Riviere 《Canadian Metallurgical Quarterly》1999,37(3):867-869
Species-specific nested PCR was used to detect Treponema amylovorum, Treponema denticola, Treponema maltophilum, Treponema medium, Treponema pectinovorum, Treponema socranskii, and Treponema vincentii in dental plaque. Subjects with periodontitis harbored all species, but T. pectinovorum and T. vincentii were not found in plaque from disease-free subjects. 相似文献
28.
Bernhard C. Lippold B rbel H. Lippold Beat K. Sutter Wolfgang Gunder 《Drug development and industrial pharmacy》1990,16(11):1725-1747
Plasticized aqueous ethyl cellulose (EC) dispersions (AquacoatR ECD-30) are incompatible with concentrated electrolytes but stable with nonelectrolytes. The minimum film formation temperature (MFT) decreases with increasing plasticizer content, from 81°C to about 30°C with 20% dibutyl sebacate (DBS) in the resulting film. The plasticiser has to penetrate completely into the EC particles before film formation to obtain optimal plastification, the lowest film formation temperature and high permeability of the resulting film. This takes more than 5 hours with 20% DBS. Films prepared from plasticized dispersion with short standing times show craters of former plasticizer droplets. With increasing plasticizer content the sticking point of the films decreases. The plasticizer induce a high water absorption of the films: more than 30% with 23-26% DBS or diethyl phthalate (DEP). DBS is hardly released from the films within 5 hours, in contrast to DEP. Thus, the absorbed water is completely swelling water in case of DBS and partially also substitution water in case of DEP. The films squeeze out cetylalcohol (CA) and also sodium lauryl sulfate (NaLS) during storage, this may change the permeability of the films. EC contains a small amount of carboxylic groups which explains the pH dependent release of drugs from pellets coated with aqueous EC dispersions. 相似文献
29.
In this paper we examine the validity of Lotka's law and Zipf'slaw for research output in 15 top journals of economics in
the period 1977to 1997. Our data for individual authors satisfy a general form of Lotka'slaw. We find increasing competition
over time among economists on the individuallevel. However, publications in top journals are concentrated heavily whenthe
institutional level is under consideration. Research output of institutionscan be fit adequately by Zipf's law.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
30.
Paul R. Hollis Robert J. Mobley Jyoti Bhuju Amy N. Abell Carrie Hayes Sutter Thomas R. Sutter 《International journal of molecular sciences》2022,23(17)
Cytochrome P4501B1 (CYP1B1) is elevated in breast cancer. Studies indicate a relationship between CYP1B1 and aggressive cancer phenotypes. Here, we report on in vitro studies in triple-negative breast cancer cell lines, where knockdown (KD) of CYP1B1 was used to determine the influence of its expression on invasive cell phenotypes. CYP1B1 KD in MDA-MB-231 cells resulted in the loss of mesenchymal morphology, altered expression of epithelial–mesenchymal genes, and increased claudin (CLDN) RNA and protein. CYP1B1 KD cells had increased cell-to-cell contact and paracellular barrier function, a reduced rate of cell proliferation, abrogation of migratory and invasive activity, and diminished spheroid formation. Analysis of clinical breast cancer tumor samples revealed an association between tumors exhibiting higher CYP1B1 RNA levels and diminished overall and disease-free survival. Tumor expression of CYP1B1 was inversely associated with CLDN7 expression, and CYP1B1HI/CLDN7LOW identified patients with lower median survival. Cells with CYP1B1 KD had an enhanced chemosensitivity to paclitaxel, 5-fluorouracil, and cisplatin. Our findings that CYP1B1 KD can increase chemosensitivity points to therapeutic targeting of this enzyme. CYP1B1 inhibitors in combination with chemotherapeutic drugs may provide a novel targeted and effective approach to adjuvant or neoadjuvant therapy against certain forms of highly metastatic breast cancer. 相似文献