全文获取类型
收费全文 | 1878篇 |
免费 | 5篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 3篇 |
化学工业 | 41篇 |
金属工艺 | 7篇 |
机械仪表 | 5篇 |
建筑科学 | 5篇 |
能源动力 | 6篇 |
轻工业 | 42篇 |
水利工程 | 1篇 |
石油天然气 | 1篇 |
无线电 | 6篇 |
一般工业技术 | 38篇 |
冶金工业 | 1719篇 |
原子能技术 | 3篇 |
自动化技术 | 9篇 |
出版年
2021年 | 4篇 |
2019年 | 4篇 |
2018年 | 2篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 5篇 |
2011年 | 7篇 |
2010年 | 5篇 |
2009年 | 6篇 |
2008年 | 8篇 |
2007年 | 9篇 |
2006年 | 6篇 |
2005年 | 5篇 |
2004年 | 6篇 |
2003年 | 8篇 |
2002年 | 6篇 |
2001年 | 4篇 |
1999年 | 50篇 |
1998年 | 506篇 |
1997年 | 285篇 |
1996年 | 202篇 |
1995年 | 105篇 |
1994年 | 107篇 |
1993年 | 105篇 |
1992年 | 20篇 |
1991年 | 31篇 |
1990年 | 31篇 |
1989年 | 22篇 |
1988年 | 26篇 |
1987年 | 27篇 |
1986年 | 24篇 |
1985年 | 23篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 12篇 |
1981年 | 17篇 |
1980年 | 16篇 |
1979年 | 2篇 |
1978年 | 7篇 |
1977年 | 34篇 |
1976年 | 94篇 |
1975年 | 7篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1972年 | 3篇 |
1964年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1886条查询结果,搜索用时 15 毫秒
991.
The purpose of this investigation was to compare outcomes in the immediate posttransplant period for hemodialysis (HD) and peritoneal (PD) dialysis patients who received cadaveric renal transplantation. Data were obtained from the United Network of Organ Sharing on all cadaveric graft recipients who were dialysis-dependent at the time of transplantation between April 1994 and December 1995. Baseline characteristics were compared between groups, and multivariate logistic regression was performed with outcome measures including urine production in the first 24 h posttransplantation (U24), requirement for dialysis in the first week posttransplant (FWDIAL), and treatment for acute rejection during the initial hospitalization. The odds of oliguria (not producing urine in the first 24 h) were 1.49 (1.28 to 1.74) times higher in HD versus PD patients. After adjustment for other comorbid conditions including age, gender, race, HLA mismatch, time on dialysis, panel-reactive antibodies, and cold and warm ischemia time, the odds of oliguria were 1.60 (1.14 to 2.25) times higher in black HD patients compared with PD patients and 1.29 (1.06 to 1.57) times higher in white HD patients. In a similar manner, after adjustment for significant comorbid conditions, the odds of requiring dialysis in the first week were 1.56 (1.22 to 2.0) times higher in black HD patients versus PD patients and 1.40 (1.21 to 1.60) times higher in white HD patients. The rate of acute rejection was similar during the first hospitalization. These results suggest that there is an association between hemodialysis and delayed graft function. Differences in biocompatibility between the two modalities could potentially be responsible. 相似文献
992.
SL Stewart KC Swallen SL Glaser PL Horn-Ross DW West 《Canadian Metallurgical Quarterly》1998,54(2):774-781
Although ethnic population counts measured by the United States Census are based on self-identification, the same is not necessarily true of cases reported to cancer registries. The use of different ethnic classification methods for numerators and denominators may therefore lead to biased estimates of cancer incidence rates. The extent of such misclassification may be assessed by conducting an ethnicity survey of cancer patients and estimating the proportion misclassified using double sampling models that account for sample stratification. For two ethnic categories, logistic regression may be used to model self-identified ethnicity as a function of demographic variables and the fallible classification method. Incidence rates then may be adjusted for misclassification using regression results to estimate the number of cancer cases of a given age, sex, and site in each self-identified ethnic group. An example is given using this method to estimate ethnic misclassification of San Francisco Bay area Hispanic cancer patients diagnosed in 1990. Results suggest that the number of cancer cases reported as Hispanic is an underestimate of the number of cases self-identified as Hispanic, resulting in an underestimate of Hispanic cancer rates. 相似文献
993.
PL Calvo J Kansopon K Sra S Quan R DiNello R Guaschino G Calabrese F Danielle MR Brunetto F Bonino AL Massaro A Polito M Houghton AJ Weiner 《Canadian Metallurgical Quarterly》1998,36(1):227-233
Recently, some empirical studies have shown an effect of body mass on take-off ability in birds, supporting the theory that birds with increased fat loads face a greater predation risk. Small wintering birds accumulate fat reserves of about 10% of their fat-free body mass during the day to survive long, cold, winter nights. Theoretically, mass-dependent predation risk could be an important factor affecting their daily foraging routines. I studied the take-off ability of wintering willow tits, Parus montanus, in relation to their fat load. Willow tits were on average 7.7% heavier at dusk than at dawn but there was no measurable effect of body mass on take-off ability. The results indicate that the relatively small fat loads accumulated during a day by willow tits do not increase the risk of predation as a consequence of reduced take-off ability. Copyright 1998 The Association for the Study of Animal Behaviour. 相似文献
994.
Protective immunity to Pasteurella multocida heat-labile toxin by intranasal immunization in rabbits
MA Suckow TL Bowersock K Nielsen CE Chrisp PL Frandsen EB Janovitz 《Canadian Metallurgical Quarterly》1995,45(5):526-532
The amyloidogenic peptides, amyloid-beta (A beta) and human amylin, are the major constituents of amyloid deposits found in patients with the chronic degenerative disorders Alzheimer's disease (AD) and type 2 diabetes, respectively. Recent studies have shown that a variety of inflammatory proteins such as cytokines are associated with the amyloid deposits of AD brain tissues. Therefore, in the present study, we sought to determine whether A beta and/or human amylin could modulate the various inflammatory activities of eosinophils. We observed that human amylin but not A beta peptides inhibited the in vitro interleukin-5 (IL-5)-mediated survival of cord blood-derived eosinophils (CBEs) in a concentration-dependent manner. By contrast, rat amylin, a nonamyloidogenic peptide that is highly homologous to human amylin, failed to affect the IL-5-mediated survival of CBEs. Similar inhibitory effects of human amylin were observed for peripheral blood eosinophils. Human amylin also enhanced the release of the cytokine granulocyte-macrophage colony-stimulating factor by CBEs that were stimulated with the calcium ionophore A23187 but was incapable of directly stimulating CBEs to release cytokines. In addition, the A23187-induced release of the inflammatory lipid mediator leukotriene C4 by CBEs was augmented by human amylin. These results suggest that the amyloidogenic peptide human amylin is capable of amplifying the various inflammatory activities of eosinophils. 相似文献
995.
Cross-linking of surface receptors results in altered receptor trafficking in the endocytic system. To better understand the cellular and molecular mechanisms by which receptor cross-linking affects the intracellular trafficking of both ligand and receptor, we studied the intracellular trafficking of the transferrin receptor (TfR) bound to multivalent-transferrin (Tf10) which was prepared by chemical cross-linking of transferrin (Tf). Tf10 was internalized about two times slower than Tf and was retained four times longer than Tf, without being degraded in CHO cells. The intracellular localization of Tf10 was investigated using fluorescence and electron microscopy. Tf10 was not delivered to the lysosomal pathway followed by low density lipoprotein but remained accessible to Tf in the pericentriolar endocytic recycling compartment for at least 60 min. The retained Tf10 was TfR-associated as demonstrated by a reduction in surface TfR number when cells were incubated with Tf10. The presence of Tf10 within the recycling compartment did not affect trafficking of subsequently endocytosed Tf. Retention of Tf10 within the recycling compartment did not require the cytoplasmic domain of the TfR since Tf10 exited cells with the same rate when bound to the wild-type TfR or a mutated receptor with only four amino acids in the cytoplasmic tail. Thus, cross-linking of surface receptors by a multivalent ligand acts as a lumenal retention signal within the recycling compartment. The data presented here show that the recycling compartment labeled by Tf10 is a long-lived organelle along the early endosome recycling pathway that remains fusion accessible to subsequently endocytosed Tf. 相似文献
996.
997.
P Bianciardi G Giordanengo EM Bortolani V Rampoldi A Rignano MC Marenghi A La Penna PL Giorgetti 《Canadian Metallurgical Quarterly》1993,41(11):501-510
There is an altered hemostatic balance in vascular-based diseases. The aim of this study was to compare a group (no. = 38) of vascular patients (aortic aneurysm, carotid obstructions arteriopathies of lower limbs) and a control group (no. = 40) and assess variations in the following endothelial factors: tPA, PAI1, vWf, fibronectin and dimer D, in differentiated degrees according to the type of pathology. These were the indicative signs of endothelial mobilization resulting in the renewed continuity of the stratum with the formation of a hemostatic plug. vWf was found to be particularly significant as a marker of an ongoing atheromasic process and its extension to various vascular districts. 相似文献
998.
999.
Irradiation of thymus with doses of 0.5 to 10 Gy and gonads with 10 Gy does not influence the growth of the tumor transplanted 10 days after irradiation and accelerates the growth of the tumor transplanted 11-12 months after exposure. Irradiation of hypophysis and hypothalamus with doses of 1 and 10 Gy accelerates the growth of the tumor transplanted 10 days and 11-12 months after exposure. In the latter case the effect was more pronounced. When thymus, hypothalamus and hypophysis were exposed simultaneously the effect was analogous to that observed after isolated exposure of hypothalamus/hypophysis but somewhat more pronounced. Irradiation of hypothalamus/hypophysis caused earlier and severer changes in the anti-tumor resistance than the exposure of thymus and gonads did. 相似文献
1000.