全文获取类型
收费全文 | 1240篇 |
免费 | 1篇 |
专业分类
化学工业 | 15篇 |
机械仪表 | 3篇 |
建筑科学 | 4篇 |
能源动力 | 4篇 |
轻工业 | 13篇 |
无线电 | 8篇 |
一般工业技术 | 3篇 |
冶金工业 | 1186篇 |
自动化技术 | 5篇 |
出版年
2021年 | 2篇 |
2020年 | 1篇 |
2019年 | 1篇 |
2015年 | 1篇 |
2014年 | 2篇 |
2013年 | 3篇 |
2012年 | 8篇 |
2011年 | 4篇 |
2010年 | 2篇 |
2009年 | 3篇 |
2008年 | 3篇 |
2007年 | 4篇 |
2006年 | 2篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 4篇 |
1999年 | 38篇 |
1998年 | 387篇 |
1997年 | 198篇 |
1996年 | 116篇 |
1995年 | 82篇 |
1994年 | 59篇 |
1993年 | 78篇 |
1992年 | 13篇 |
1991年 | 15篇 |
1990年 | 13篇 |
1989年 | 23篇 |
1988年 | 14篇 |
1987年 | 17篇 |
1986年 | 14篇 |
1985年 | 10篇 |
1983年 | 4篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 13篇 |
1977年 | 34篇 |
1976年 | 56篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有1241条查询结果,搜索用时 15 毫秒
61.
62.
63.
Font R Del Río-Celestino M Vélez D De Haro-Bailón A Montoro R 《Analytical chemistry》2004,76(14):3893-3898
The potential of near-infrared spectroscopy (NIRS) for screening the inorganic arsenic (i-As) content in the red crayfish (Procambarus clarkii Girard 1852) was assessed. Sixty-two samples belonging to this species were freeze-dried and scanned by NIRS. The i-As contents of the samples were obtained by acid digestion-solvent extraction followed by hydride generation atomic absorption spectrometry and were regressed against different spectral transformations by modified partial least-squares (MPLS) regression. Second derivative transformation equations of the raw optical data, previously standardized by applying standard normal variate and de-trending algorithms, resulted in a coefficient of determination in the cross-validation (1-VR) of 0.84, indicative of equations of good quantitative information. The standard error of cross-validation to standard deviation ratio, shown by the second derivative equation, was similar to those obtained for other trace metal calibrations reported in NIRS reflectance. Spectral information related to chromophores and lipids of the red crayfish tissues, and also the plant matter contained in their stomachs, were the main organic components used by MPLS for modeling the selected prediction equation. This pioneering use of NIRS to predict the i-As content in red crayfish represents an important savings in time and cost of analysis. 相似文献
64.
65.
66.
67.
The phosphorylation state of three identified neural-specific protein kinase C substrates (RC3, GAP-43/B-50, and MARCKS) was monitored in hippocampal slices of mice lacking the gamma-subtype of protein kinase C and wild-type controls by quantitative immunoprecipitation following 32Pi labeling. Depolarization with potassium, activation of glutamate receptors with glutamate, or direct stimulation of protein kinase C with a phorbol ester increased RC3 phosphorylation in wild-type animals but failed to affect RC3 phosphorylation in mice lacking the gamma-subtype of protein kinase C. Our results suggests the following biochemical pathway: activation of a postsynaptic (metabotropic) glutamate receptor stimulates the gamma-subtype of protein kinase C, which in turn phosphorylates RC3. The inability to increase RC3 phosphorylation in mice lacking the gamma-subtype of protein kinase C by membrane depolarization or glutamate receptor activation may contribute to the spatial learning deficits and impaired hippocampal LTP observed in these mice. 相似文献
68.
PURPOSE: We identified the incidence and types of genital and urinary anomalies, and established a plan for evaluating the urinary system in the CHARGE association. MATERIALS AND METHODS: We retrospectively reviewed the charts of 32 patients in whom the CHARGE association was diagnosed. RESULTS: Of the 32 patients identified 22 (69%) had genitourinary abnormalities. Genital anomalies, including micropenis, penile agenesis, hypospadias, chordee, cryptorchidism, a bifid scrotum, atresia of the uterus, cervix and vagina, and hypoplastic labia majora, labia minora and clitoris, were present in 18 patients (56%). Of the 24 patients who underwent renal ultrasound 10 (42%) were diagnosed with urinary tract anomalies including a solitary kidney, hydronephrosis, renal hypoplasia and duplex kidneys. Further evaluation revealed vesicoureteral reflux, neurogenic bladder secondary to spinal dysraphism, nephrolithiasis, ureteropelvic junction obstruction and a nonfunctioning upper pole in both duplex kidneys. CONCLUSIONS: There is a high incidence of genitourinary anomalies in the CHARGE association. Because of this high incidence of anomalies, patients with this condition should undergo a careful genitourinary evaluation, including renal and bladder ultrasound, and voiding cystourethrography screening. 相似文献
69.
DD Roman SH Kubo S Ormaza GS Francis AJ Bank SJ Shumway 《Canadian Metallurgical Quarterly》1997,19(5):692-697
Seventeen patients with severe cardiomyopathy underwent neuropsychological evaluation prior to and at least 1 year after successful heart transplantation. Study candidates were screened, and individuals with a history of stroke, cardiac arrest, or medical and neurological conditions which might affect brain function were excluded. Pre-transplant testing revealed normal intelligence and normal attentional, language, and executive abilities but impaired recent memory. Following heart transplant, memory functioning improved significantly, reaching normal levels. Other cognitive abilities remained unchanged. Results suggest that cardiomyopathy is associated with mesial temporal dysfunction, possibly attributable to inadequate or reduced cerebral blood flow and related hypometabolism. This cerebral dysfunction is potentially reversible following successful transplantation, which restores cardiac output and cerebrovascular perfusion. 相似文献
70.