全文获取类型
收费全文 | 5878篇 |
免费 | 8篇 |
国内免费 | 1篇 |
专业分类
综合类 | 1篇 |
化学工业 | 30篇 |
金属工艺 | 3篇 |
机械仪表 | 2篇 |
建筑科学 | 1篇 |
矿业工程 | 3篇 |
能源动力 | 1篇 |
轻工业 | 18篇 |
无线电 | 3篇 |
一般工业技术 | 11篇 |
冶金工业 | 5808篇 |
原子能技术 | 2篇 |
自动化技术 | 4篇 |
出版年
2020年 | 4篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 4篇 |
2013年 | 3篇 |
2012年 | 3篇 |
2011年 | 3篇 |
2010年 | 4篇 |
2009年 | 1篇 |
2008年 | 3篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2004年 | 6篇 |
2003年 | 12篇 |
2002年 | 1篇 |
2000年 | 2篇 |
1999年 | 184篇 |
1998年 | 1915篇 |
1997年 | 1096篇 |
1996年 | 701篇 |
1995年 | 377篇 |
1994年 | 276篇 |
1993年 | 357篇 |
1992年 | 42篇 |
1991年 | 42篇 |
1990年 | 53篇 |
1989年 | 44篇 |
1988年 | 36篇 |
1987年 | 38篇 |
1986年 | 35篇 |
1985年 | 44篇 |
1984年 | 1篇 |
1983年 | 10篇 |
1982年 | 19篇 |
1981年 | 37篇 |
1980年 | 53篇 |
1979年 | 2篇 |
1978年 | 14篇 |
1977年 | 130篇 |
1976年 | 291篇 |
1975年 | 13篇 |
1974年 | 1篇 |
1973年 | 2篇 |
1972年 | 1篇 |
1965年 | 1篇 |
1963年 | 1篇 |
1955年 | 4篇 |
排序方式: 共有5887条查询结果,搜索用时 15 毫秒
151.
152.
153.
J van Ark-Otte MA Kedde WJ van der Vijgh AM Dingemans WJ Jansen HM Pinedo E Boven G Giaccone 《Canadian Metallurgical Quarterly》1998,77(12):2171-2176
Irinotecan (CPT-11) is a semisynthetic camptothecin derivative with a broad spectrum of anti-tumour activity. Carboxylesterase (CE) catalyses the conversion of CPT-11 to SN-38 (7-ethyl-10-hydroxycamptothecin), the active form of CPT-11. The antiproliferative effects of CPT-11 and SN-38, CE-activity and topoisomerase I protein expression were investigated in five human small-cell lung cancer (SCLC) cell lines and four human non-small-cell lung cancer (NSCLC) cell lines. Antiproliferative activity, expressed as IC50 values, was determined using the MTT assay. CPT-11 was significantly more active in SCLC than in NSCLC cell lines (P = 0.0036), whereas no significant difference between histological types was observed with SN-38. A significant correlation (r2 = 0.52, P = 0.028) was observed between CE activity and chemosensitivity to CPT-11 but not to SN-38, and significantly higher CE activity was observed in SCLC compared with NSCLC cell lines (P = 0.025). Western blotting experiments showed topoisomerase I protein expressions within a factor of 2, and a granular nuclear staining was detectable in all cell lines by immunocytochemistry of cytospins. No correlation was observed between protein expression and sensitivity to CPT-11 or SN-38. Cellular and medium concentrations of CPT-11 and SN-38 were measured by high-performance liquid chromatography (HPLC) in one SCLC cell line with high CE activity and high sensitivity to CPT-11, and one NSCLC cell line with low sensitivity to CPT-11 and CE activity. Intracellular concentrations of CPT-11 and SN-38 were higher in the SCLC cell line, and this was associated with an increase in cellular uptake of CPT-11 compared with the medium, and an increased intracellular formation of SN-38. In conclusion, CE activity appears to be associated with higher sensitivity to CPT-11 in human lung cancer cell lines and may partly explain the difference in the in vitro sensitivity to CPT-11 between SCLC and NSCLC cells. The assessment of CE activity in clinical material of lung cancer patients undergoing treatment with CPT-11 may be warranted. However, other mechanisms may influence sensitivity to CPT-11, possibly including drug transport. 相似文献
154.
SA Whitmore C Settasatian J Crawford KM Lower B McCallum R Seshadri CJ Cornelisse EW Moerland AM Cleton-Jansen AJ Tipping CG Mathew M Savnio A Savoia P Verlander AD Auerbach C Van Berkel JC Pronk NA Doggett DF Callen 《Canadian Metallurgical Quarterly》1998,52(3):325-331
BACKGROUND: Both fibroblast-mediated cytokine gene therapy and bone marrow transplantation (BMT) have proven to be efficient protocols for the recovery of bone marrow depression. In this report, the effects of fibroblast-mediated interleukin (IL)-6 gene therapy, in combination with BMT, on the recovery of irradiation-induced bone marrow depression were investigated. METHODS: NIH3T3 fibroblast cells engineered to secrete IL-6 (NIH3T3-IL-6) or NIH3T3 cells transduced with the neomycin gene (NIH3T3-Neo), in combination with 10(7), 10(6), or 10(5) syngeneic bone marrow cells, were implanted into irradiated mice. RESULTS: The platelets and white blood cells in the peripheral blood of the irradiated mice increased greatly 12 days after implantation of NIH3T3-IL-6 cells and BMT, the white blood cell counts were restored to a normal level 32 days after the combined therapy, and the platelet number was obviously higher than that in mice implanted with NIH3T3-Neo and BMT. Twenty and 25 days after the combined therapy, the mice showed accelerated recovery of colony-forming unit (CFU)-granulocyte/macrophages and CFU-megakaryocytes when compared with the mice implanted with NIH3T3-Neo cells and BMT. Ten days after lethal irradiation with gamma rays, the spleens formed more CFU-spleen in mice implanted with NIH3T3-IL-6 cells and BMT than in mice injected with phosphate-buffered saline or NIH3T3-Neo cells. Combined therapy with NIH3T3-IL-6 cell implantation and BMT delayed the survival period of the hematopoietic-depressed mice significantly when compared with therapy with NIH3T3-Neo cell implantation and BMT. CONCLUSIONS: These data demonstrated that the combined therapy of fibroblast-mediated IL-6 gene therapy and BMT could significantly promote the recovery of irradiation-induced hematopoietic depression. 相似文献
155.
MH Mullerworth P Angelopoulos MA Couyant AM Horton SM Robinson OU Petring PJ Mitchell JJ Presneill 《Canadian Metallurgical Quarterly》1998,66(4):1242-1245
The use of PCR to amplify a specific virA gene fragment serves as a highly specific and sensitive method to detect virulent bacteria of the genus Shigella and enteroinvasive Escherichia coli. Amplification of a 215-bp DNA band was obtained by using isolated genomic DNA of Shigella, individual cells of Shigella dysenteriae, and mayonnaise contaminated with S. dysenteriae. Moreover, a multiplex PCR with specific (virA) and bacterium-restricted (16S ribosomal DNA) primers generated an amplification product of approximately 755 bp for all bacteria tested and an additional 215-bp product for Shigella and enteroinvasive E. coli. 相似文献
156.
157.
A G protein gamma subunit-like domain shared between RGS11 and other RGS proteins specifies binding to Gbeta5 subunits 总被引:1,自引:0,他引:1
BE Snow AM Krumins GM Brothers SF Lee MA Wall S Chung J Mangion S Arya AG Gilman DP Siderovski 《Canadian Metallurgical Quarterly》1998,95(22):13307-13312
Regulators of G protein signaling (RGS) proteins act as GTPase-activating proteins (GAPs) toward the alpha subunits of heterotrimeric, signal-transducing G proteins. RGS11 contains a G protein gamma subunit-like (GGL) domain between its Dishevelled/Egl-10/Pleckstrin and RGS domains. GGL domains are also found in RGS6, RGS7, RGS9, and the Caenorhabditis elegans protein EGL-10. Coexpression of RGS11 with different Gbeta subunits reveals specific interaction between RGS11 and Gbeta5. The expression of mRNA for RGS11 and Gbeta5 in human tissues overlaps. The Gbeta5/RGS11 heterodimer acts as a GAP on Galphao, apparently selectively. RGS proteins that contain GGL domains appear to act as GAPs for Galpha proteins and form complexes with specific Gbeta subunits, adding to the combinatorial complexity of G protein-mediated signaling pathways. 相似文献
158.
The best prosthetic material is one which provides the best mechanical resistance with the best biological tolerance. In order to assess the mechanical and histological properties of abdominal wall prostheses, we performed experimental tests in animal models comparing four materials: polypropylene, dacron, polyglactine 910 and a dacron-polyglactine 910 composite. One hundred thirty rabbits were used including 10 controls and 120 test animals. A medial laparotomy was closed with an antemuscular aponevrotic prosthesis in the test animals. Animals were sacrificed at one, two and three months after the operation. Abdominal wall and prosthesis samples were tested to determine resistance to pressure and extension, deformability and elasticity. Histology tests were also done to determine resistance quality and biological tolerance. Dacron was tolerated best and was less resistant than polypropylene, though resistance was satisfactory. There was no advantage with polyglactine compared with non-resorbable prostheses; its only indication would be a septic site. The composite material tested had a resistance comparable with that of dacron but was less well tolerated. 相似文献
159.
AM Pollock 《Canadian Metallurgical Quarterly》1995,310(6994):1580-1584
The Association of Metropolitan Authorities has recently proposed that responsibility for the NHS should pass from health authorities to local authorities. One of the fiercest debates at the outset of the NHS was whether the hospitals should be run by local authorities. In the end the minister for health, Aneurin Bevan, decided against local democracy and in favour of a national health service. His arguments included the fact that equality of treatment could not be guaranteed if facilities varied with local finances and that even the largest authorities were not big enough to pool risks and expertise. All these arguments still apply today, and the recent changes in community care provide an insight into how a market model of local authority control might work. The changes have been accompanied by a shift from public to private sector provision and the introduction of charges for services that the NHS once provided free. As important, the willingness and ability of local authorities to raise extra revenue from local taxes and charges affect the service they can provide, so leading to inequalities of provision. Local authorities have yet to make the case that they can preserve the fundamental principles and benefits of the NHS, including its reliance on central taxation and unified funding formulas. 相似文献
160.
P Laharrague D Larrouy AM Fontanilles N Truel A Campfield R Tenenbaum J Galitzky JX Corberand L Pénicaud L Casteilla 《Canadian Metallurgical Quarterly》1998,12(9):747-752
Inhaled nitric oxide (iNO) has been shown to improve oxygenation in severe persistent pulmonary hypertension of the newborn (PPHN). However, PPHN is often associated with various lung diseases. Thus, response to iNO may depend upon the aetiology of neonatal acute respiratory failure. A total of 150 (29 preterm and 121 term) newborns with PPHN were prospectively enrolled on the basis of oxygenation index (OI) higher than 30 and 40, respectively. NO dosage was stepwise increased (10-80 ppm) during conventional mechanical or high-frequency oscillatory ventilation while monitoring the oxygenation. Effective dosages ranged from 5 to 20 ppm in the responders, whereas iNO levels were unsuccessfully increased up to 80 ppm in the nonresponders. Within 30 min of iNO therapy, OI was significantly reduced in either preterm neonates (51+/-21 vs 23+/-17, P < .0001) or term infants with idiopathic or acute respiratory distress syndrome (45+/-20 vs 20+/-17, P < .0001), 'idiopathic' PPHN (39+/-14 vs 14+/-9, P < .0001), and sepsis (55+/-25 vs 26+/-20, P < .0001) provided there was no associated refractory shock. Improvement in oxygenation was less significant and sustained (OI=41+/-16 vs 28+/-18, P < .001) in term neonates with meconium aspiration syndrome and much less (OI=58+/-25 vs 46+/-32, P < .01) in those with congenital diaphragmatic hernia. Only 21 of the 129 term newborns (16%) required extracorporeal membrane oxygenation (57% survival). Survival was significantly associated with the magnitude in the reduction in OI at 30 min of iNO therapy, a gestational age > or =34 weeks, and associated diagnosis other than congenital diaphragmatic hernia. Conclusion, iNO improves the oxygenation in most newborns with severe hypoxaemic respiratory failure including preterm neonates. However, response to iNO is disease-specific. Furthermore, iNO when combined with adequate alveolar recruitment and limited barotrauma using exogenous surfactant and HFOV may obviate the need for extracorporeal membrane oxygenation in many term infants. 相似文献