全文获取类型
收费全文 | 4373篇 |
免费 | 50篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 12篇 |
综合类 | 3篇 |
化学工业 | 318篇 |
金属工艺 | 93篇 |
机械仪表 | 64篇 |
建筑科学 | 104篇 |
矿业工程 | 10篇 |
能源动力 | 50篇 |
轻工业 | 172篇 |
水利工程 | 19篇 |
石油天然气 | 11篇 |
无线电 | 134篇 |
一般工业技术 | 341篇 |
冶金工业 | 2811篇 |
原子能技术 | 13篇 |
自动化技术 | 271篇 |
出版年
2022年 | 14篇 |
2021年 | 16篇 |
2020年 | 11篇 |
2018年 | 25篇 |
2017年 | 20篇 |
2016年 | 29篇 |
2015年 | 24篇 |
2014年 | 27篇 |
2013年 | 91篇 |
2012年 | 61篇 |
2011年 | 83篇 |
2010年 | 61篇 |
2009年 | 53篇 |
2008年 | 66篇 |
2007年 | 79篇 |
2006年 | 80篇 |
2005年 | 56篇 |
2004年 | 64篇 |
2003年 | 70篇 |
2002年 | 74篇 |
2001年 | 45篇 |
2000年 | 51篇 |
1999年 | 124篇 |
1998年 | 818篇 |
1997年 | 476篇 |
1996年 | 307篇 |
1995年 | 188篇 |
1994年 | 157篇 |
1993年 | 180篇 |
1992年 | 55篇 |
1991年 | 47篇 |
1990年 | 60篇 |
1989年 | 45篇 |
1988年 | 56篇 |
1987年 | 58篇 |
1986年 | 55篇 |
1985年 | 47篇 |
1984年 | 37篇 |
1983年 | 38篇 |
1982年 | 41篇 |
1981年 | 47篇 |
1980年 | 31篇 |
1979年 | 23篇 |
1978年 | 32篇 |
1977年 | 78篇 |
1976年 | 152篇 |
1975年 | 23篇 |
1974年 | 17篇 |
1973年 | 20篇 |
1972年 | 19篇 |
排序方式: 共有4426条查询结果,搜索用时 46 毫秒
991.
MC Courrèges F Benencia CE Coto EJ Massouh FC Coulombié 《Canadian Metallurgical Quarterly》1994,43(2):135-140
The first reported case of cerebellar metastasis from primary clear cell adenocarcinoma of the fallopian tube is presented. Initially diagnosed as stage Ia, the patient underwent total abdominal hysterectomy, bilateral salpingo-oophorectomy and omentectomy, followed by cisplatin-based chemotherapy and whole pelvic irradiation. Thirty six months later multiple pulmonary metastases were detected that did not respond to chemotherapy. Later the patient presented with cerebellar metastasis. She received whole brain radiotherapy and steroids. The brain lesion partially responded and the patient's neurologic symptoms improved. Throughout there was no evidence of local recurrence. This case suggests that with the prolonged survival achieved by aggressive treatment occult brain metastases might become apparent. 相似文献
992.
The behaviour of a plate strip with local as well as global imperfections is investigated in this paper. The function used to describe the deformation of the plate was based on a previously conducted experimental investigation. The behaviour of the plate well into the large-deflection post-buckling range has been considered. It is shown that various buckling modes are possible and the effects of the imperfections on the buckling and post-buckling behaviour are presented. 相似文献
993.
994.
CE Ford NP Skiba H Bae Y Daaka E Reuveny LR Shekter R Rosal G Weng CS Yang R Iyengar RJ Miller LY Jan RJ Lefkowitz HE Hamm 《Canadian Metallurgical Quarterly》1998,280(5367):1271-1274
Both the alpha and betagamma subunits of heterotrimeric guanine nucleotide-binding proteins (G proteins) communicate signals from receptors to effectors. Gbetagamma subunits can regulate a diverse array of effectors, including ion channels and enzymes. Galpha subunits bound to guanine diphosphate (Galpha-GDP) inhibit signal transduction through Gbetagamma subunits, suggesting a common interface on Gbetagamma subunits for Galpha binding and effector interaction. The molecular basis for interaction of Gbetagamma with effectors was characterized by mutational analysis of Gbeta residues that make contact with Galpha-GDP. Analysis of the ability of these mutants to regulate the activity of calcium and potassium channels, adenylyl cyclase 2, phospholipase C-beta2, and beta-adrenergic receptor kinase revealed the Gbeta residues required for activation of each effector and provides evidence for partially overlapping domains on Gbeta for regulation of these effectors. This organization of interaction regions on Gbeta for different effectors and Galpha explains why subunit dissociation is crucial for signal transmission through Gbetagamma subunits. 相似文献
995.
996.
997.
998.
Insulin-like growth factor II blocks apoptosis of N-myc2-expressing woodchuck liver epithelial cells
N-myc2 and insulin-like growth factor II (IGF-II) are coordinately overexpressed in the great majority of altered hepatic foci, which are the earliest precancerous lesions observed in the liver of woodchuck hepatitis virus carrier woodchucks, and these genes continue to be overexpressed in hepatocellular carcinomas (HCCs). We have investigated the function of these genes in woodchuck hepatocarcinogenesis by using a woodchuck liver epithelial cell line (WC-3). WC-3 cells react positively with a monoclonal antibody (12.8.5) against woodchuck oval cells, suggesting a lineage relationship with oval cells. Overexpression of N-myc2 in three WC-3 cell lines caused their morphological transformation and increased their growth rate and saturation density in medium containing 10% serum. Removal of serum from the medium increased cell death of the N-myc2-expressing lines, whereas cell death in control lines was minimal. The death of N-myc2-expressing WC-3 cells was accompanied by nucleosomal fragmentation of cellular DNA, and DAPI (4',6-diamidino-2-phenylindole) staining revealed condensation and fragmentation of the nuclei, suggesting that N-myc2-expressing WC-3 cells undergo apoptosis in the absence of serum. In colony regression assays, conducted in the absence of serum, control colonies were stable, while N-myc2-expressing colonies regressed to various degrees. Addition of recombinant human IGF-II to the serum-free medium blocked both cell death and colony regression in all the N-myc2-expressing lines. Therefore, coordinate overexpression of N-myc2 and IGF-II in woodchuck altered hepatic foci may allow cells which otherwise might die to survive and progress to hepatocellular carcinoma. 相似文献
999.
Scores on three measures of dissociation were compared between 48 African American and 48 Caucasian men being treated for substance abuse at a VA Medical Center. The three assessment instruments included the Dissociative Experience Scale, the Questionnaire of Experiences of Dissociation, and the North Carolina Index of Dissociation. Groups were matched with respect to age, education, marital status, number of previous treatments, IQ, employment status, history of childhood abuse, and psychological discomfort. In each case, the African-American group scored higher, with statistical significance being achieved on two of the three instruments. Potential implications of these findings were discussed and future research was suggested. 相似文献
1000.
G Kent R Iles CE Bear LJ Huan U Griesenbach C McKerlie H Frndova C Ackerley D Gosselin D Radzioch H O'Brodovich LC Tsui M Buchwald AK Tanswell 《Canadian Metallurgical Quarterly》1997,100(12):3060-3069
The leading cause of mortality and morbidity in humans with cystic fibrosis is lung disease. Advances in our understanding of the pathogenesis of the lung disease of cystic fibrosis, as well as development of innovative therapeutic interventions, have been compromised by the lack of a natural animal model. The utility of the CFTR-knockout mouse in studying the pathogenesis of cystic fibrosis has been limited because of their failure, despite the presence of severe intestinal disease, to develop lung disease. Herein, we describe the phenotype of an inbred congenic strain of CFTR-knockout mouse that develops spontaneous and progressive lung disease of early onset. The major features of the lung disease include failure of effective mucociliary transport, postbronchiolar over inflation of alveoli and parenchymal interstitial thickening, with evidence of fibrosis and inflammatory cell recruitment. We speculate that the basis for development of lung disease in the congenic CFTR-knockout mice is their observed lack of a non-CFTR chloride channel normally found in CFTR-knockout mice of mixed genetic background. 相似文献