全文获取类型
收费全文 | 2520篇 |
免费 | 32篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 38篇 |
化学工业 | 316篇 |
金属工艺 | 20篇 |
机械仪表 | 27篇 |
建筑科学 | 10篇 |
矿业工程 | 1篇 |
能源动力 | 21篇 |
轻工业 | 66篇 |
无线电 | 91篇 |
一般工业技术 | 269篇 |
冶金工业 | 1554篇 |
原子能技术 | 64篇 |
自动化技术 | 77篇 |
出版年
2023年 | 3篇 |
2022年 | 21篇 |
2021年 | 20篇 |
2020年 | 20篇 |
2019年 | 17篇 |
2018年 | 17篇 |
2017年 | 16篇 |
2016年 | 27篇 |
2015年 | 11篇 |
2014年 | 16篇 |
2013年 | 56篇 |
2012年 | 42篇 |
2011年 | 65篇 |
2010年 | 30篇 |
2009年 | 42篇 |
2008年 | 38篇 |
2007年 | 47篇 |
2006年 | 48篇 |
2005年 | 42篇 |
2004年 | 36篇 |
2003年 | 34篇 |
2002年 | 27篇 |
2001年 | 25篇 |
2000年 | 30篇 |
1999年 | 77篇 |
1998年 | 518篇 |
1997年 | 282篇 |
1996年 | 204篇 |
1995年 | 104篇 |
1994年 | 103篇 |
1993年 | 106篇 |
1992年 | 20篇 |
1991年 | 35篇 |
1990年 | 30篇 |
1989年 | 28篇 |
1988年 | 39篇 |
1987年 | 30篇 |
1986年 | 25篇 |
1985年 | 20篇 |
1984年 | 11篇 |
1983年 | 7篇 |
1982年 | 10篇 |
1981年 | 20篇 |
1980年 | 23篇 |
1979年 | 8篇 |
1978年 | 13篇 |
1977年 | 28篇 |
1976年 | 76篇 |
1975年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有2554条查询结果,搜索用时 15 毫秒
31.
32.
CG Moertel TR Fleming JS Macdonald DG Haller JA Laurie 《Canadian Metallurgical Quarterly》1993,11(12):2386-2390
PURPOSE: To determine the frequency and nature of hepatic toxicity associated with fluorouracil (5-FU) plus levamisole adjuvant therapy. PATIENTS AND METHODS: All patients had resection of stage II or stage III colon cancer and were randomized to receive observation only, levamisole alone, or 5-FU plus levamisole. Serial liver function studies were documented in 1,025 patients who did not develop recurrence during the year of therapy. RESULTS: One hundred forty-nine (39.6%) of 376 patients treated with 5-FU plus levamisole showed laboratory abnormalities consistent with hepatic toxicity, compared with 16.3% of 251 patients treated with levamisole alone and 16.1% of 398 untreated controls. Most common was elevation of alkaline phosphatase, frequently accompanied by elevations of transaminase or serum bilirubin. Characteristically, these changes were mild, not associated with symptoms, and resolved when therapy was stopped. In some instances, they were associated with elevated carcinoembryonic antigen (CEA) tests or with fatty liver seen on computed tomographic (CT) scan or liver biopsy. CONCLUSION: Mild and reversible hepatotoxicity is a common consequence of 5-FU plus levamisole adjuvant therapy, but this is only rarely symptomatic. However, the oncologist should be alert to this phenomenon, since the associated laboratory and imaging findings may simulate those associated with hepatic metastasis. 相似文献
33.
TR Smyth 《Canadian Metallurgical Quarterly》1994,20(1):27-36
The distribution of type I interleukin-1 receptor (IL-1R1) mRNA in the rat brain was examined by in situ hybridization technique. IL-1R1 mRNA was expressed in several brain regions including the anterior olfactory nucleus, medial thalamic nucleus, posterior thalamic nucleus, basolateral amygdaloid nucleus, ventromedial hypothalamic nucleus, arcuate nucleus, median eminence, mesencephalic trigeminal nucleus, motor trigeminal nucleus, facial nucleus and Purkinje cells of the cerebellum. Furthermore, we identified neuronal expression of IL-1R1 mRNA using simultaneous detection (double in situ hybridization) of IL-1R1 mRNA with neuron specific enolase mRNA. In addition to the expression in neuronal cells, IL-1R1 mRNA was also expressed on the vascular walls and the epithelial cells of the choroid plexus and the ventricles. These findings suggest the possibility that IL-1 produces its multiple effects on the central nervous system through the actions not only on neuronal cells but also on endothelial and epithelial cells. 相似文献
34.
TR Tripi 《Canadian Metallurgical Quarterly》1997,46(11):609-614
The case of a girl with Binder syndrome (maxillonasal-dysplasia) is reported. The girl has a peculiar face due to severely depressed nasal bridge, the nasofrontal angle is absent and the nose is hypoplastic with flattened alae and nasal tip; the upper lip has a convex contour with poorly developed philtrum. The premaxillary is hypoplastic. Lateral and postero-anterior cephalometric findings are presented. 相似文献
35.
36.
TR Kosten R Schottenfeld D Ziedonis J Falcioni 《Canadian Metallurgical Quarterly》1993,181(6):358-364
Buprenorphine at 2 mg and 6 mg daily was compared with methadone at 35 mg and 65 mg during 24 weeks of maintenance among 125 opioid-dependent patients. As hypothesized, 6 mg of buprenorphine were superior to 2 mg of buprenorphine in reducing illicit opioid use, but higher dosage did not improve treatment retention. Self-reported illicit opioid use declined substantially in all groups, but by the third month, significantly more heroin abuse was reported at 2 mg than at 6 mg of buprenorphine or of methadone. From an initial average of $1860/month, month 3 usage dropped to $41 (methadone 65 mg), $73 (methadone 35 mg), $118 (buprenorphine 6 mg), and $351/month (buprenorphine 2 mg). Days of use also dropped from 29 days to 1.7 (methadone 65 mg), 2.8 (methadone 35 mg), 4.0 (buprenorphine 6 mg), and 6.6 days/month (buprenorphine 2 mg). This relatively low efficacy for 2 mg of buprenorphine persisted through month 6 of the trial, with 7.2 days/month and $235/month of use for buprenorphine at 2 mg versus 1.9 days/month and $65/month for the other three groups. Increased opioid abuse also was associated with significantly greater and persistent opioid withdrawal symptoms. Our secondary hypothesis, that buprenorphine would be equivalent to methadone in efficacy, was not supported. Treatment retention was significantly better on methadone (20 vs. 16 weeks), and methadone patients had significantly more opioid-free urines (51% vs. 26%). Abstinence for at least 3 weeks was also more common on methadone than buprenorphine (65% vs. 27%).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
37.
H Hanaue K Kanno M Mukai H Kubo K Tobita H Nakasaki T Tajima T Mitomi R Endo 《Canadian Metallurgical Quarterly》1993,18(1-2):1-4
Increased monoamine metabolism in experimental herpes simplex virus (HSV) encephalitis is well established. Both serotonin (5-HT) and dopamine (DA) systems are affected. HSV invades the raphe nuclei after its entry into the brain stem. However, no studies have been published concerning influences of HSV on the neurotransmitters in the raphe. In the present study, concentrations of 5-HT and DA and their metabolites in the raphe nuclei and related brain regions in rabbits with fulminant HSV encephalitis have been analyzed using high-pressure liquid chromatography. Encephalitis was induced by corneal inoculation with HSV. Homovanillic acid (HVA) and dihydroxyphenyl acetic acid (DOPAC) concentrations and HVA/DA ratios were increased in the raphe nuclei suggesting increased DA turnover. The most substantial changes were bilaterally decreased 5-HT and 5-hydroxyindoleacetic acid (5-HIAA) concentrations in the raphe nuclei. The decrease in the raphe 5-HT was reflected also to the projection areas in the hemispheres, where 5-HT concentrations were lower in HSV-inoculated rabbits than in controls. The changes strongly suggest a direct influence of HSV on serotoninergic neurons. Since the ventral parts of the limbic system have rich serotoninergic afferents from the raphe, this also suggests that HSV may reach hemispheres in HSV encephalitis from the brain stem via the ascending serotoninergic system. 相似文献
38.
39.
40.
VA Barnes FA Treiber H Davis TR Kelley WB Strong 《Canadian Metallurgical Quarterly》1998,22(11):1079-1083
OBJECTIVE: To examine the impact of central adiposity upon hemodynamic functioning at rest and during stress in adolescents. DESIGN: Cross-sectional, correlational study. SUBJECTS: 46 White and 49 Black normotensive adolescents with family histories of essential hypertension. MEASUREMENTS: Systolic and diastolic blood pressure (SBP, DBP), cardiac output and total peripheral resistance responses were assessed at rest, during postural change, video game challenge and forehead cold stimulation. Specific lower and higher waist-to-hip ratio (WHR) tertiles were created for each gender and then integrated for analyses. This resulted in a lower WHR tertile of 11 Whites and 21 Blacks and an upper WHR tertile of 15 Whites and 17 Blacks. RESULTS: No differences in age, gender or ethnicity proportions were found between tertile groups (all P > 0.21). The upper WHR group showed greater body weight, waist and hip circumferences, body mass index (BMI), triceps skinfold and body surface area (all P < 0.001). Controlling for peripheral (that is, triceps skinfold) and overall (that is, BMI) adiposity, the upper WHR group exhibited greater SBP (that is, peak response minus mean pre-stressor level) to all three stressors and greater DBP reactivity to postural change and cold pressor (all P < 0.05). CONCLUSION: Central adiposity appears to adversely influence hemodynamic functioning during adolescence. Underlying mechanisms responsible for these associations require exploration. 相似文献