全文获取类型
收费全文 | 2066篇 |
免费 | 42篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 2篇 |
综合类 | 12篇 |
化学工业 | 24篇 |
金属工艺 | 13篇 |
机械仪表 | 10篇 |
建筑科学 | 7篇 |
矿业工程 | 3篇 |
能源动力 | 9篇 |
轻工业 | 16篇 |
水利工程 | 32篇 |
石油天然气 | 1篇 |
无线电 | 29篇 |
一般工业技术 | 30篇 |
冶金工业 | 1877篇 |
原子能技术 | 2篇 |
自动化技术 | 46篇 |
出版年
2022年 | 3篇 |
2021年 | 2篇 |
2020年 | 9篇 |
2019年 | 7篇 |
2018年 | 12篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 11篇 |
2014年 | 14篇 |
2013年 | 22篇 |
2012年 | 3篇 |
2011年 | 11篇 |
2010年 | 9篇 |
2009年 | 6篇 |
2008年 | 8篇 |
2007年 | 3篇 |
2006年 | 5篇 |
2005年 | 19篇 |
2004年 | 9篇 |
2003年 | 9篇 |
2002年 | 16篇 |
2001年 | 10篇 |
2000年 | 5篇 |
1999年 | 59篇 |
1998年 | 613篇 |
1997年 | 375篇 |
1996年 | 220篇 |
1995年 | 108篇 |
1994年 | 89篇 |
1993年 | 99篇 |
1992年 | 15篇 |
1991年 | 23篇 |
1990年 | 16篇 |
1989年 | 25篇 |
1988年 | 31篇 |
1987年 | 19篇 |
1986年 | 16篇 |
1985年 | 14篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 15篇 |
1978年 | 2篇 |
1977年 | 44篇 |
1976年 | 99篇 |
1975年 | 3篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1955年 | 4篇 |
排序方式: 共有2113条查询结果,搜索用时 0 毫秒
71.
Giant-cell interstitial Pneumonia (GIP) is a very uncommon respiratory disease. The majority of cases of GIP are caused by exposure to cobalt, tungsten and other hard metals. In this report, we describe GIP in a patient who worked in gas station and dealt in propane gas vessels. He presented with clinical features of chronic interstitial lung disease and underwent an open lung biopsy that showed DIP-like reaction with large numbers of intra-alveolar macrophages and numerous large, multinucleated histiocytes which were admixed with the macrophages. Analysis of lung tissue for hard metals was done. Cobalt was the main component of detected hard metals. Corticosteroid therapy was started and he recovered fully. 相似文献
72.
CH Brenner 《Canadian Metallurgical Quarterly》1998,62(6):1558-60; author reply 1560-1
73.
Iron is required for cell proliferation of all living species. Moreover, iron excess may be involved in the development of hepatocellular carcinoma. In this study we analyzed the effects of deferoxamine, an iron chelator, on normal porcine hepatocyte proliferation. We confirmed that hepatocytes isolated from young pigs proliferate in the presence of insulin and fetal calf serum as shown by [3H] methyl-thymidine incorporation, presence of mitotic figures and increase in cell number. This was paralleled by nuclear expression of p34cdc2 and its associated histone H1 kinase activity. In the presence of deferoxamine, [3H] methyl-thymidine incorporation, expression of nuclear proteins (p34cdc2 and PCNA) and H1 kinase activity were drastically reduced. In addition, in contrast with control cultures, cells in S-phase were not detected by flow cytometry. These data suggest that iron chelation by deferoxamine can arrest the progression of porcine hepatocytes in the G1 phase of the cell cycle. 相似文献
74.
75.
Exercise has a noted effect on skin blood flow and temperature. We aimed to characterize the normal skin temperature response to exercise by thermographic imaging. A study was conducted on ten healthy and active subjects (age=25.8+/-0.7 years) who were exposed to graded exercise for determination of maximal oxygen consumption (VO2 max), and subsequently to constant loads corresponding to 50%, 70%, and 90% of VO2 max. The skin temperature response during 20 min of constant load exercise is characterized by an initial descending limb, an ascending limb and a quasi-steady-state period. For 50% VO2 max, the temperature decrease rate was - 0.0075+/-0.001 degrees C/s during a time interval of 390+/-47 s and the temperature increase rate was 0.0055+/-0.0031 degrees C/s during a time interval of 484+/-99 s. The level of load did not influence the temperature decrease and increase rates. In contrast, during graded load exercise, a continuous temperature decrease of -0.0049+/-0.0032 degrees C/s was observed throughout the test. In summary, the thermographic skin response to exercise is characterized by a specific pattern which reflects the dynamic balance between hemodynamic and thermoregulatory processes. 相似文献
76.
We examined the mechanisms of norathyriol on the serotonin-induced increased permeability of rat heart endothelial cell monolayers. The present study showed that the activation of rat heart endothelial cell protein kinase C by phorbol myristate acetate led to the dose-dependent increase in endothelial permeability to albumin, an effect that was inhibited by staurosporine (a protein kinase inhibitor). Staurosporine also attenuated the serotonin-induced increase in permeability. Norathyriol abolished both serotonin- and phorbol myristate acetate-induced permeability. We investigated whether norathyriol, by inhibiting protein kinase C activation, attenuated the serotonin-induced permeability. Immunofluorescence studies demonstrated that norathyriol prevented the redistribution of protein kinase C isozymes following stimulation with serotonin. Western blot analysis showed that norathyriol significantly inhibited the serotonin-induced translocation of the alpha protein kinase C isozyme from the cytosolic to the particulate fraction. In conclusion, norathyriol attenuates the serotonin-induced permeability of rat heart endothelial cells to macromolecules in association with inhibition of protein kinase C activation. This decrease in endothelial cell permeability may be one of the mechanisms for the protective effects of norathyriol against edema formation in response to inflammatory agonists in vivo. 相似文献
77.
E Au PT Ang F Seow-Choen KC Soo CH Low HC Chng BK Ng 《Canadian Metallurgical Quarterly》1998,27(5):733-737
Carcinoma of the large bowel is the second leading cause of cancer mortality in Singapore. Although the great majority of patients are discovered at a stage where resection with curative intent is possible, almost half of the patients afflicted will die of it. The combination of 5-fluorouracil + levamisole used in patients with curatively resected high risk Dukes B2 and all Dukes' C colon cancers has been shown to reduce cancer recurrence rate and improve overall survival. Since 1990 adjuvant chemotherapy has been recommended for this group of patients. This report describes patients treated in Singapore, their toxicities and their outcome. A total of 341 patients were treated between 1990 and 1996. Treatment compliance was 71.8%. Toxicity was moderate with mainly grade 1-2 nausea and vomiting, diarrhoea, stomatitis, alopecia, and neutropenia. There was 1 treatment-related death. Median recurrence-free interval was 81 months and median survival was not reached at 90 months. This regimen is tolerable. Until further randomised reports comparing 5-fluorouracil + levamisole to other combinations are available, this combination chemotherapy is recommended to patients after surgical resection of the high risk Dukes' B2 and Dukes' C colon cancer to reduce cancer recurrence and improve overall survival. 相似文献
78.
79.
80.
Maung-Maung-Thwin P Gopalakrishnakone R Yuen CH Tan 《Canadian Metallurgical Quarterly》1996,34(2):183-199
Daboiatoxin (DbTx), the PLA2 neurotoxin from Daboia russelli siamensis venom, was shown to bind specifically and saturably to rat cerebrocortical synaptosomes and synaptic membrane fragments. Two families of binding sites were detected by equilibrium binding analysis in the presence and absence of Ca2+. Scatchard analysis of biphasic plateaus revealed Kdl 5 nM and Bmax1, 6 pmoles/mg protein, and Kd2 80 nM and Bmax2 20 pmoles/mg protein, respectively, for the high- and low-affinity binding sites. The binding of 125I-DbTx to synaptosomes did not show marked dependence on Ca2+, Mg2+, Co2+ and Sr2+. Native DbTx was the only strong competitor to 125I-DbTx synaptosomal binding (IC50 12.5 nM, KI 5.5 nM). Two other crotalid PLA2 neurotoxins, crotoxin CB and mojave toxin basic subunit, and nontoxic C. Atrox PLA2 enzyme, were relatively weaker inhibitors, while two viperid PLA2 neurotoxins, ammodytoxin A and VRV PL V, were very weak inhibitors. Crotoxin CA was a poor inhibitor even at microM concentrations, whereas no inhibitory effect at all was observed with crotoxin CACB, ammodytoxin C, VRV PL VIIIa, taipoxin, beta-bungarotoxin, or with PLA2 enzymes from N. naja venom, E. schistosa venom, bee venom and porcine pancreas. All other pharmacologically active ligands examined (epinephrine, norepinephrine, histamine, choline, dopamine, serotonin, GABA, naloxone, WB-4101, atropine, hexamethonium and alpha-bun-garotoxin) also failed to interfere with 125I-DbTx binding. As those competitors that showed partial inhibition were effective only at microM concentration range compared to the Kd (5 nM) of 125I-DbTx synaptosomal binding, DbTx could well recognize a different neuronal binding site. Rabbit anti-DbTx polyclonal antisera completely blocked the specific binding. When a range of Ca2+ and K+ channels modulators were examined, Ca2+ channel blockers (omega-conotoxins GVIA and MVIIC, taicatoxin, calciseptine and nitrendiprene) did not affect the binding even at high concentrations, while charybdotoxin was the only K+ channel effector that could partially displace 125I-DbTx synaptosomal binding amongst the K+ channel blockers tested (apamin, dendrotoxin-I, iberiotoxin, MCD-peptide, 4-aminopyridine and tetraethylammonium), suggesting that neither K+ nor Ca2+ channels are associated with DbTx binding sites. 相似文献