全文获取类型
收费全文 | 6046篇 |
免费 | 38篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 13篇 |
综合类 | 1篇 |
化学工业 | 263篇 |
金属工艺 | 23篇 |
机械仪表 | 45篇 |
建筑科学 | 93篇 |
矿业工程 | 6篇 |
能源动力 | 55篇 |
轻工业 | 201篇 |
水利工程 | 14篇 |
石油天然气 | 4篇 |
无线电 | 213篇 |
一般工业技术 | 274篇 |
冶金工业 | 4680篇 |
原子能技术 | 26篇 |
自动化技术 | 180篇 |
出版年
2023年 | 16篇 |
2022年 | 19篇 |
2021年 | 26篇 |
2020年 | 27篇 |
2019年 | 31篇 |
2018年 | 22篇 |
2017年 | 22篇 |
2016年 | 35篇 |
2015年 | 17篇 |
2014年 | 35篇 |
2013年 | 75篇 |
2012年 | 55篇 |
2011年 | 78篇 |
2010年 | 55篇 |
2009年 | 37篇 |
2008年 | 57篇 |
2007年 | 72篇 |
2006年 | 63篇 |
2005年 | 55篇 |
2004年 | 44篇 |
2003年 | 54篇 |
2002年 | 49篇 |
2001年 | 46篇 |
2000年 | 36篇 |
1999年 | 176篇 |
1998年 | 1522篇 |
1997年 | 881篇 |
1996年 | 529篇 |
1995年 | 313篇 |
1994年 | 272篇 |
1993年 | 264篇 |
1992年 | 51篇 |
1991年 | 74篇 |
1990年 | 58篇 |
1989年 | 54篇 |
1988年 | 68篇 |
1987年 | 60篇 |
1986年 | 57篇 |
1985年 | 69篇 |
1984年 | 28篇 |
1983年 | 20篇 |
1982年 | 29篇 |
1981年 | 39篇 |
1980年 | 55篇 |
1979年 | 15篇 |
1978年 | 21篇 |
1977年 | 113篇 |
1976年 | 175篇 |
1975年 | 17篇 |
1974年 | 18篇 |
排序方式: 共有6091条查询结果,搜索用时 0 毫秒
41.
42.
43.
44.
45.
C Kanthou SM Kanse P Newman VV Kakkar O Benzakour 《Canadian Metallurgical Quarterly》1995,6(8):753-760
alpha-Thrombin, a key enzyme of the coagulation cascade, is also a potent mitogen for many cell types. In the present study, the responsiveness to alpha-thrombin of cultured human vascular smooth muscle cells (HVSMC) derived from either vein or normal and atherosclerotic arteries was investigated. All HVSMC populations examined responded mitogenically to alpha-thrombin. However, the extent of this response varied between different cell populations. No significant differences were observed between HVSMC derived from vein versus artery or atherosclerotic versus normal tissues. The responsiveness of a specific HVSMC culture to alpha-thrombin was not affected by cell density and remained constant over several passages. Unlike platelet-derived growth factor BB (PDGF-BB), alpha-thrombin did not exhibit any significant chemotactic effects on HVSMC or induce their anchorage independent growth in semi-solid medium. The hypothesis that the observed variability in HVSMC responsiveness to alpha-thrombin is due to the heterogeneity of cultured HVSMC is raised and discussed. 相似文献
46.
47.
PA Smanik KY Ryu KS Theil EL Mazzaferri SM Jhiang 《Canadian Metallurgical Quarterly》1997,138(8):3555-3558
The active iodide uptake of the thyroid gland in humans is mediated by the human sodium iodide symporter (hNIS). In this report, we show that hNIS expression was detected primarily in thyroid tissue, but also in breast, colon, and ovary tissues. Expression of hNIS is greatly reduced in thyroid tumors compared to normal thyroid tissue. Among tumor tissues, hNIS expression appears to be variable, consistent with the variable response to radioiodide treatment observed for thyroid carcinomas. The coding region of hNIS is interrupted by 14 introns, and the nucleotide sequence of each exon-intron junction is reported. Using this information, an alternatively spliced form of hNIS was identified. Finally, the chromosome location of the hNIS gene was mapped to chromosome 19p. 相似文献
48.
49.
DL Newton S Walbridge SM Mikulski W Ardelt K Shogen SJ Ackerman SM Rybak RJ Youle 《Canadian Metallurgical Quarterly》1994,14(2):538-544
Purkinje cell toxicity is one of the characteristic features of the Gordon phenomenon, a syndrome manifested by ataxia, muscular rigidity, paralysis, and tremor that may lead to death (Gordon, 1933). Two members of the RNase superfamily found in humans, EDN (eosinophil-derived neurotoxin) and ECP (eosinophil cationic protein), cause the Gordon phenomenon when injected intraventricularly into guinea pigs or rabbits. We have found that another member of the RNase superfamily, an antitumor protein called onconase, isolated from Rana pipiens oocytes and early embryos, will also cause the Gordon phenomenon when injected into the cerebrospinal fluid of guinea pigs at a dose similar to that of EDN (LD50, 3-4 micrograms). Neurologic abnormalities of onconase-treated animals were indistinguishable from those of EDN-treated animals, and histology showed dramatic Purkinje cell loss in the brains of onconase-treated animals. The neurotoxic activity of onconase correlates with ribonuclease activity. Onconase modified by iodoacetic acid to eliminate 70% and 98% of the ribonuclease activity of the native enzyme displays a similar decrease in ability to cause the Gordon phenomenon. In contrast, the homologous bovine pancreatic RNase A injected intraventricularly at a dose 5000 times greater than the LD50 dose of EDN or onconase is not toxic and does not cause the Gordon phenomenon. A comparison of the RNase activities of EDN, onconase, and bovine pancreatic RNase A using three pancreatic RNA substrates demonstrates that onconase is orders of magnitude less active enzymatically than EDN and RNase A. Thus, another member of the RNase superfamily in addition to EDN and ECP can cause the Gordon phenomenon.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
50.
Ockene Judith K.; Kristeller Jean; Pbert Lori; Hebert James R.; Luippold Rose; Goldberg Robert J.; Landon Joan; Kalan Kathryn 《Canadian Metallurgical Quarterly》1994,13(3):278
Patterns of smoking cessation using 6- and 12-mo follow-up data are reported for 1,261 primary care patients randomized to 3 physician-delivered smoking interventions: advice only (AO), counseling (CI), and counseling plus availability of nicotine-containing gum (CI?+?NCG). One-week point-prevalence cessation rates at 12 mo did not differ among the interventions: AO (15.2%), CI (12.9%) and CI?+?NCG (16.7%). However, maintained cessation rates (abstinent at both 6 and 12 mo) increased with intervention intensity: AO (6.0%), CI (7.8%), and CI?+?NCG (10.0%): Test of trend χ–2?=?5.06, p?=?.02. CI?+?NCG was significantly higher than AO (p?=?.02). The findings support the following conclusions: Brief physician delivered intervention with availability of nicotine-containing gum can have a beneficial long-term effect on smoking cessation, and cohort data as well as point-prevalence rates are important when assessing the long-term impact of lifestyle interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献