全文获取类型
收费全文 | 1530篇 |
免费 | 3篇 |
国内免费 | 2篇 |
专业分类
化学工业 | 10篇 |
金属工艺 | 1篇 |
机械仪表 | 5篇 |
建筑科学 | 2篇 |
轻工业 | 10篇 |
无线电 | 6篇 |
一般工业技术 | 12篇 |
冶金工业 | 1486篇 |
自动化技术 | 3篇 |
出版年
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 3篇 |
2011年 | 1篇 |
2009年 | 1篇 |
2008年 | 2篇 |
2007年 | 1篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2004年 | 3篇 |
2003年 | 6篇 |
2002年 | 2篇 |
2000年 | 1篇 |
1999年 | 44篇 |
1998年 | 422篇 |
1997年 | 269篇 |
1996年 | 183篇 |
1995年 | 95篇 |
1994年 | 83篇 |
1993年 | 95篇 |
1992年 | 11篇 |
1991年 | 24篇 |
1990年 | 23篇 |
1989年 | 10篇 |
1988年 | 15篇 |
1987年 | 12篇 |
1986年 | 16篇 |
1985年 | 19篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1982年 | 8篇 |
1981年 | 8篇 |
1980年 | 18篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 55篇 |
1976年 | 82篇 |
1975年 | 4篇 |
1974年 | 1篇 |
1965年 | 1篇 |
1955年 | 1篇 |
排序方式: 共有1535条查询结果,搜索用时 31 毫秒
991.
AA Amin BJ Baldwin A Gürlek MJ Miller SS Kroll GP Reece GR Evans GR Robb MA Schusterman 《Canadian Metallurgical Quarterly》1998,14(6):365-8; discussion 368-9
Over the past decade, free-tissue transfer has greatly improved the quality of oncology-related head and neck reconstruction. As this technique has developed, second free flaps have been performed for aesthetic improvement of the reconstructed site. This study evaluated the indications for and the success of second free flaps. Medical files for patients who underwent second free flaps for head and neck reconstruction at the University of Texas M.D. Anderson Cancer Center, from May 1, 1988 to November 30, 1996, were reviewed. The flaps were classified as being either immediate (done within 72 hr) or delayed (done within 2 years) reconstructions. Indications, risk factors, recipient vessels, outcome, and complications were analyzed. Of the 28 patients included in this study, 12 had immediate (nine as salvage after primary free flap failure, and three for reconstruction of a soft-tissue defect), and 16 had delayed second free flaps (two for reconstruction of a defect resulting from excision of recurrent tumors, and 14 for aesthetic improvement). Reconstruction sites included the oral cavity in 18 patients; the midface in six; the skull base in two; and the scalp in two. The success rate for the second free flaps was 96 percent. Five patients had significant wound complications. In a substantial number of cases, identical recipient vessels were used for both the first and second free flaps. The authors conclude that second free flaps can play an important role in salvaging or improving head and neck reconstruction in selected patients. In many cases, the same recipient vessels can be used for both the first and second flaps. 相似文献
992.
VM Aquino MM Mustafa L Vaickus R Wooley GR Buchanan 《Canadian Metallurgical Quarterly》1998,20(5):474-476
OBJECTIVE: To determine whether cardiac monitoring is required in children sustaining electric shock at Australian household voltage. METHODOLOGY: Records of patients admitted via the Emergency Department of Princess Margaret Hospital for Children, Perth, Australia, for the period 1968-96 were retrospectively reviewed. The initial ECG findings of patients with an electric shock were recorded, and the development of any arrhythmia. RESULTS: Forty-four patients were identified, 40 of whom had sustained a household electrical injury. One patient had an abnormal ECG on admission, none developed an arrhythmia and all survived. CONCLUSIONS: Routine cardiac monitoring is not required after exposure to Australian household electricity supply if the child is asymptomatic and has a normal ECG on presentation. 相似文献
993.
F Cardillo E de Paula GR Oliveira S Marangoni B Oliveira NC Meirelles 《Canadian Metallurgical Quarterly》1997,41(3):497-509
1) The Soret region absorption spectrum of erythrocruorin (ERC) obtained from Glossoscolex paulistus, shows that oxy-ERC has a maximum absorption peak at 416 nm while the deoxy-ERC from has a maximum at 427 nm. 2) In the presence of a specific antiserum (anti-ERC) and of anti-ERC immunoglobulin G raised in rabbits, there is a deviation to low wavelengths in the maximum absorption peak of deoxy-ERC while for the oxy form a red-shift is noticed. These shifts accompanied an increased affinity of the hemeprotein for oxygen, possibly because of changes in the overall macromolecular conformation. 3) A decrease in the oxygen affinity of erythrocruorin is observed when large amounts of non-specific serum are used. The same effect is observed in the presence of serum albumin, probably as a result of non-specific binding between the albumin and erythrocruorin. 4) The fluorimetric titration of erythrocruorin with anti-ERC Fab fragments results in a decrease in the intrinsic tryptophan fluorescence of the hemeprotein, a response indicative of a modification in the ERC's quaternary structure. 相似文献
994.
In this pilot study, 99Tcm-labelled human immunoglobulin G (99Tcm-HIG) was evaluated as a lymphoscintigraphic agent in five rabbits. It was injected intradermally into the web space of the hind legs of the rabbits (37 MBq/0.1 ml). Sequential scintigrams were obtained using a gamma camera for 120 min. The injection site and the hind legs were massaged post-injection. Blood samples were obtained at 5, 15, 30, 60, 90 and 120 min. Two of the rabbits were killed after 2 h. Their organs were weighed and tissue specimens were obtained, weighed and counted against a standard using a gamma counter. The lymph channels and the lymph nodes were well visualized on the scintigrams. The background activity was very low, making interpretation easier. About 30% of the injected dose migrated from the injection site by 2 h. The mean popliteal lymph node uptake was 5.71 +/- 4.62% per gram of tissue. The lymph node to other tissue concentration ratios were very high, ranging from 63:1 for the kidneys to 1099:1 for the heart. We conclude that 99Tcm-HIG is a promising new agent for the visualization of the lymphatic system due to its easy labelling procedure, the stability of the label, its widespread availability and good image quality. It may potentially be useful in detecting and evaluating inflammatory lymph nodes. 相似文献
995.
Phase II trial of 96-hour paclitaxel plus oral estramustine phosphate in metastatic hormone-refractory prostate cancer 总被引:1,自引:0,他引:1
GR Hudes F Nathan C Khater N Haas M Cornfield B Giantonio R Greenberg L Gomella S Litwin E Ross S Roethke C McAleer 《Canadian Metallurgical Quarterly》1997,15(9):3156-3163
PURPOSE: To evaluate the antitumor activity of 96-hour paclitaxel and daily oral estramustine phosphate (EMP) in patients with metastatic hormone-refractory prostate cancer (HRPC). PATIENTS AND METHODS: Thirty-four patients with adenocarcinoma of the prostate that progressed after one or more hormonal therapies and a trial of antiandrogen withdrawal were enrolled onto this phase II trial. Patients received paclitaxel 120 mg/m2 by 96-hour intravenous (i.v.) infusion on days 1 through 4 of each 21-day cycle, together with daily oral EMP 600 mg/m2/d, continuously. RESULTS: Four of nine patients with measurable disease had objective responses (one complete response [CR] and three partial responses [PRs]) in liver (two patients) or nodes (two patients) of 2, 6, 8, and 20 months' duration. Of 25 assessable patients with metastases limited to bone, 14 had a > or = 50% decline in pretreatment prostate-specific antigen (PSA) level sustained for at least 6 weeks and seven had a > or = 80% decline. Overall, 17 of 32 patients (53.1%) with elevated pretreatment PSA levels had a > or = 50% decline of PSA and nine (28.1%) had a > or = 80% decrease. The main toxicities (> or = grade 2) were nausea, fluid retention, and fatigue, which occurred in 33%, 33%, and 24.2% of patients. Median time to progression, based on increasing PSA level and other clinical criteria, was 22.5 weeks. The estimated median overall survival time is 69 weeks. CONCLUSION: The combination of EMP and 96-hour paclitaxel is an active regimen for patients with HRPC. These results further support the therapeutic strategy of combining agents that impair microtubule function by complementary mechanisms. 相似文献
996.
JC Wright M Chambers GR Mullen LJ Swango GH D'Andrea AJ Boyce 《Canadian Metallurgical Quarterly》1997,31(1-2):127-131
A random sample of private small-animal practices in Alabama submitted sera from dogs with known tick contact. A total of 579 samples from the three geographic regions of the state were collected (58% of the targeted sample size). Sera were screened for antibodies to Borrelia burgdorferi using an indirect fluorescent antibody (IFA) test which had a sensitivity and specificity of greater than 90%. Anti-B burgdorferi titers of > or = 1:64 were considered to be positive, based on results from B. burgdorferi-inoculated dogs. Ten of the 579 samples (1.7%) were positive, and titers ranged from 1:64 to 1:512. Seropositive dogs were found throughbout the state, and there was no significant difference in seroprevalence by region (Mantel-Haenszel chi 2, P = 0.85). These results indicate that the seroprevalence for canine Lyme disease in Alabama is low and that use of the canine Lyme disease vaccine is not justified. 相似文献
997.
998.
Extracellular ATP (ATPo) elicits a robust change in the concentration of intracellular Ca2+ ([Ca2+]i) in fura-2-loaded mouse thymocytes. Most thymocytes (60%) exposed to ATPo exhibited a biphasic rise in [Ca2+]i; [Ca2+]i rose slowly at first to a mean value of 260 nM after 163 s and then increased rapidly to a peak level of 735 nM. In many cells, a declining plateau, which lasted for more than 10 min, followed the crest in [Ca2+]i. Experiments performed in the absence of extracellular [Ca2+]o abolished the rise in thymocyte [Ca2+]i, indicating that Ca2+ influx, rather than the release of stored Ca2+, is stimulated by ATPo. ATPo- mediated Ca2+ influx was potentiated as the [Mg2+]o was reduced, confirming that ATP4- is the active agonist form. In the absence of Mg2+o, 3'-O-(4-benzoyl)benzoyl-ATP (BzATP) proved to be the most effective agonist of those tested. The rank order of potency for adenine nucleotides was BzATP4->ATP4->MgATP2->ADP3-, suggesting purinoreceptors of the P2X7/P2Z class mediate the ATPo response. Phenotyping experiments illustrate that both immature (CD4-CD8-, CD4+CD8+) and mature (CD4+CD8-, CD4-CD8+) thymocyte populations respond to ATP. Further separation of the double-positive population by size revealed that the ATPo-mediated [Ca2+]i response was much more pronounced in large (actively dividing) than in small (terminally differentiated) CD4+CD8+ thymocytes. We conclude that thymocytes vary in sensitivity to ATPo depending upon the degree of maturation and suggest that ATPo may be involved in processes that control cellular differentiation within the thymus. 相似文献
999.
MJ Nirenberg J Chan RA Vaughan GR Uhl MJ Kuhar VM Pickel 《Canadian Metallurgical Quarterly》1997,17(14):5255-5262
The dopamine transporter (DAT) plays an important role in the plasmalemmal reuptake of dopamine and, thus, in the termination of normal dopaminergic neurotransmission. DAT is also a major binding site for cocaine and other stimulants, the psychoactive effects of which are associated primarily with the inhibition of dopamine reuptake within mesocorticolimbic dopaminergic neurons. We used electron microscopy with an anti-peptide antiserum directed against the N-terminal domain of DAT to determine the subcellular localization of this transporter in the rat ventral tegmental area (VTA), the region that contains the cell bodies and dendrites of these dopaminergic neurons. We show that in the VTA, almost 95% of the DAT immunogold-labeled profiles are neuronal perikarya and dendrites, and the remainder are unmyelinated axons. Within perikarya and large proximal dendrites, almost all of the DAT immunogold particles are associated with intracellular membranes, including saccules of Golgi and cytoplasmic tubulovesicles. In contrast, within medium- to small-diameter dendrites and unmyelinated axons, most of the DAT gold particles are located on plasma membranes. In dually labeled tissue, peroxidase reaction product for the catecholamine-synthesizing enzyme tyrosine hydroxylase is present in DAT-immunoreactive profiles. These findings suggest that intermediate and distal dendrites are both the primary sites of dopamine reuptake and the principal targets of cocaine and related psychostimulants within dopaminergic neurons in the VTA. 相似文献
1000.
MA Rubin A Jurach GR Zanolla RL Boemo DO Souza CF de Mello 《Canadian Metallurgical Quarterly》1997,8(17):3713-3716
Guanidino compounds play specific physiological and pathological roles in the central nervous system. We investigated the effect of an intrahippocampal infusion of GMP (a guanidino compound) administered immediately post-training on the inhibitory avoidance learning paradigm in rats. Bilateral intrahippocampal micro-injection of GMP (0-30 nmol) caused a dose-dependent increase in test step-down latencies which was completely reversed by intrahippocampal co-administration of muscimol or baclofen (GABA agonists) or preadministration (15 min pre-training, i.p.) of MK-801 (an NMDA antagonist). These results provide evidence for a participation of GABA and NMDA receptors in the GMP-induced increase in the test step-down latencies. 相似文献