全文获取类型
收费全文 | 1199篇 |
免费 | 1篇 |
专业分类
化学工业 | 2篇 |
矿业工程 | 1篇 |
一般工业技术 | 1篇 |
冶金工业 | 1191篇 |
自动化技术 | 5篇 |
出版年
2017年 | 1篇 |
2007年 | 1篇 |
2006年 | 1篇 |
2003年 | 1篇 |
2000年 | 1篇 |
1999年 | 27篇 |
1998年 | 377篇 |
1997年 | 219篇 |
1996年 | 109篇 |
1995年 | 79篇 |
1994年 | 50篇 |
1993年 | 72篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 15篇 |
1989年 | 14篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 15篇 |
1985年 | 7篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 15篇 |
1978年 | 1篇 |
1977年 | 31篇 |
1976年 | 113篇 |
1975年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有1200条查询结果,搜索用时 31 毫秒
81.
Breeding animal transports between parts of our institute were used assessing effects of age of animals, of breed, of their functional state and of individual specificity of reaction patterns using peripheral venous blood samples. Increased mean values of Hb, Hk, body temperature, total protein, albumin, FT4, T4, FT3, T3, cortisol, adrenaline and decreased ones of body weight, Pa, Fe, noradrenaline were found after transport stress. Comparing age matched groups of DSB and HF breed higher concentrations of total protein, creatinine, lactate, cortisol, FT4, T3 and FT3 and lower ones of albumin, blood urea and Fe could be observed in animals of DSB breed before and after transport. Strong correlations existed on 14 variables within animals before and after transport stress meaning there could be individual specificity of some blood parameters. 相似文献
82.
Systemic lupus erythematosus (SLE) is an inflammatory systemic disease that causes organ damage by the deposition of autoantibodies and complement activating immune complexes or by vascular occlusion due to procoagulant states associated with antiphospholipid antibodies. The vast majority of cases occur in women of childbearing age. SLE is diagnosed on the basis of its clinical manifestations and the demonstration of characteristic immunological phenomena, especially anti-nuclear antibodies. The prognosis in SLE has shown a distinct improvement over recent decades, the 5-year survival rate now approaching or exceeding 90%. The 15-year survival rate of 63 to 79%, on the other hand, underscores the need for further advances in diagnosis and treatment of the disease. Management of the disease includes regular monitoring of disease activity, avoidance of predisposing factors and close supervision of therapy. Drug therapy is guided by the activity and severity of the leading organ manifestations and ranges from nonsteroidal antirheumatic drugs to intensive treatment with cytotoxic agents. Corticosteroids remain irreplaceable for the control of acute flares. Antimalarials and azathioprine are important long term drugs for treating mild or moderate disease activity. Intravenous pulse cyclophosphamide is safer than other regimens and at least as effective as oral cyclophosphamide for severe lupus nephritis. It is also effective in the treatment of central nervous disease and of other organ-threatening manifestations. Recently, an intensified protocol which included cyclophosphamide induced long term treatment-free remission in 60% of patients. The toxicity of cyclophosphamide is considerable, but can be ameliorated by various measures. The value of several new immunosuppressants and other compounds remains to be determined. 相似文献
83.
Gastrointestinal carcinoid tumor is often considered the most common neuroendocrine tumor of the small intestine. The overall incidence of 1% in the general population is quite low. Extraadrenal paragangliomas are rarer still, and the incidence of both of these tumors in the malignant state is exceedingly rare. This article describes the case of a patient who had both a malignant carcinoid tumor as well as a malignant retroperitoneal paraganglioma occurring synchronously. A review of the literature concerning these tumors is also presented. 相似文献
84.
A variety of initiation procedures have been used to develop oral ethanol consumption. Using the sucrose-substitution procedure, oral self-administration of ethanol-water solutions with ethanol concentrations as high as 40% can be initiated in food- and fluid-sated rats. An important question for these models is the relationship between ethanol concentration and self-administration patterns after initiation. This study examined the differential patterns of ethanol self-administration maintained by a range of ethanol solutions (10 to 30%) over a 5-week period, compared with rats maintained on 10% ethanol for 5 weeks. In 43 male Long Evans rats, the sucrose-substitution procedure was used to initiate responding maintained by 10% ethanol on a Fixed Ratio 4 schedule of reinforcement. The ethanol concentration presented was then increased to 30% in stepwise fashion and then returned to 10% [Ethanol Concentration Manipulation (ECM) group, n = 32], or 10% ethanol was maintained as the reinforcer for 5 weeks [Control (Con) group, n = 11]. Significant increases in ethanol intake and decreases in responding were associated with increased ethanol concentration. Although no overall differences in total session responding were observed in either group between week 1 and week 5 (10E vs. 10E), examination of changes in initial low responders of the ECM group revealed significant increases in responding that were not observed in the initial low responders of the Con group. Significant increases in momentary response rates were observed on both the ECM and Con groups, independent of the ethanol concentration presented. Increases in response rate in the ECM group were the result of increases in initial low rate and high rate responders; however, the increased response rates in the Con group were the result of increases only in the initial low rate responders. These data suggest that the ECM procedure can aid in the initiation of ethanol self-administration and may be particularly useful in rats of heterogeneous stock. 相似文献
85.
86.
JB Helms D Helms-Brons B Brügger I Gkantiragas H Eberle W Nickel B Nürnberg HH Gerdes FT Wieland 《Canadian Metallurgical Quarterly》1998,273(24):15203-15208
Heterotrimeric G proteins have been implicated in the regulation of intracellular protein transport, but their mechanism of action remains unclear. In vivo, secretion of chromogranin B, tagged with the green fluorescent protein, was inhibited by the addition of a general activator of trimeric G proteins (AlF4-) to stably transfected Vero cells and resulted in an accumulation of the tagged protein in the Golgi apparatus. In an in vitro assay that reconstitutes intra-Golgi protein transport, we find that a membrane-bound and AlF4--sensitive factor is involved in the fusion reaction. To determine whether this effect is mediated by a heterotrimeric G protein localized to COPI-coated transport vesicles, we determined the presence of G proteins on these vesicles and found that they were segregated relative to the donor membranes. Because G proteins do not have an obvious sorting, retention, or retrieval signal, we considered the possibility that other interactions might be responsible for this segregation. In agreement with this, we found that trimeric G proteins from isolated Golgi membranes were partially insoluble in Triton X-100. Identification of the proteins that interact with the heterotrimeric G proteins in the Golgi-derived detergent-insoluble complex might help to reveal the regulation of protein secretion mediated by heterotrimeric G proteins. 相似文献
87.
C Schmid M Deng D Hammel M Weyand HM Loick HH Scheld 《Canadian Metallurgical Quarterly》1998,17(10):1024-1028
BACKGROUND: The risk and outcome in patients undergoing left ventricular assist device (LVAD) implantation on an emergency basis is still unclear. METHODS: Since April 1993, 40 patients received a Novacor and 8 patients a Heartmate LVAD in our institution. Patients with emergency LVAD placement were compared with the remainder in a retrospective manner. Parameters studied included underlying heart disease, preimplantation dysfunction of kidney, liver, lung, and cerebrum, interval of mechanical support, outcome, and complications. RESULTS: Patients with emergency LVAD placement predominantly were seen with postcardiotomy heart failure (47%) or acute myocarditis (20%) (group A) whereas elective and urgent candidates for LVAD implantation mainly had dilative cardiomyopathy (67%) or ischemic heart disease (30%) (group B). The incidence of secondary organ failure was significantly higher for all organs in group A patients (p < .01). Mean support interval in patients who underwent emergency LVAD implantation was lower (74+/-79 days vs 115+/-80 days), and fewer patients could be forwarded to heart transplantation in this group (22% vs 78%, p < .01). Moreover, bleeding complications were increased in group A (66% vs 30%, p < .01), but not thromboembolism and infection. CONCLUSION: In conclusion, the overall success rate after emergency LVAD implantation was lower, with bleeding being the most frequent complication. To achieve acceptable outcomes in disastrous situations, LVADs should be placed as early as possible. 相似文献
88.
Rats experience anorexia and reduction or cessation in growth after being provided a zinc-deficient diet. While zinc deficient, intake levels may be reduced 50% or more compared to control rats. In the present report, diurnal food intake patterns of male Sprague-Dawley rats were measured during zinc deficiency. In Study 1, rats consuming a modified AIN-93 diet were tested during the dark phase using an automated food weighing system. In zinc-deficient animals (Zn-), the onset of the first meal of the dark phase was delayed compared to zinc-adequate rats (Zn+; 106+/-47 vs. 23+/-5 min; p<0.05) and the number of meals consumed during the dark phase was reduced in Zn- vs. Zn+ rats (3.9+/-0.5 vs 7.1+/-0.4; p<0.05). In Study 2, diurnal food intake patterns were tested using a three-choice macronutrient self-selection paradigm of carbohydrate-, protein-, and fat-containing diets made deficient or adequate in zinc (1 or 30 mg Zn/kg diet). Food intake was recorded in the early-, mid-, late-dark period (4 h each) and light period (12 h). Carbohydrate intake was 70% of total intake of both Zn+ and Zn- rats during the first 5 days, but decreased significantly to 50% in the Zn- group during the last 5 days. Fat intake increased significantly in the Zn- group during the last 5 days. This increase was the result of 4 of 15 Zn- rats increasing their intake of fat significantly. Results of this study indicate that zinc status alters dark phase and macronutrient selection patterns by delaying consumption of the initial meal of the dark phase, reducing the average meal number and by changing the dominant macronutrient preference of some Zn- rats. 相似文献
89.
R Ullmann A Schwendel H Klemen G Wolf I Petersen HH Popper 《Canadian Metallurgical Quarterly》1998,29(10):1145-1149
Typical and atypical carcinoids (TC, ATC) and small (SCLC) and large cell neuroendocrine carcinomas (LCNEC) constitute the spectrum of neuroendocrine lung tumors. Chromosomal aberrations have not been studied in LCNEC and only rarely in carcinoids. Only SCLCs have been investigated frequently for chromosomal aberrations. We compared three typical and four atypical carcinoids, one atypical carcinoid/SCLC mixed type, three SCLC, and three LCNEC for chromosomal gains and losses using comparative genomic hybridization. Typical carcinoids showed either no changes or only few chromosomal gains. Atypical carcinoids appeared genetically heterogeneous: One case had no aberrations, and three cases had few aberrations; two of them showed a deletion of 11q. SCLC and LCNEC were characterized by many gains and losses, especially similar changes of 3p, 5q, 5p, and 13q. Although ATC resemble LCNEC morphologically, there were no similarities at the genetic level. We have found a reciprocal relationship of prognosis and the amount of aberrations. TCs and ATCs with few chromosomal changes have the best prognosis, whereas SCLCs and LCNECs were generally characterized by a great amount of aberrations and worst prognosis. There was no unbalanced aberration common in all types of neuroendocrine tumors of the lung. 相似文献
90.
An actin-depolymerizing marine natural product, mycalolide B, and a related compound, kabiramide D, were labeled with biocytin, a biotin derivative, and used to specify target molecules in cultured rat 3Y1 fibroblasts. Mycalolide B exhibited the ability to bind to various intracellular proteins, probably through the Michael addition of a sulfhydryl group to C5 of mycalolide B. However, no intracellular proteins other than actin apparently reacted with biocytinylated kabiramide D, demonstrating that the binding of kabiramide D to actin was highly specific. Cells treated with biocytinylated kabiramide D followed by staining with fluorescein isothiocyanate-conjugated avidin showed that biocytinylated kabiramide D bound to stress fibers composed of F-actin, although the staining intensity was weaker than the fluorescent phalloidin staining. The assay for the binding of kabiramide D to actin, which had previously been treated with other actin-depolymerizing agents, showed that the actin-binding site for kabiramide D was the same as that for bistheonellide A, but not those for latrunculin A and cytochalasin D. 相似文献