全文获取类型
收费全文 | 691篇 |
免费 | 0篇 |
专业分类
综合类 | 2篇 |
化学工业 | 12篇 |
轻工业 | 4篇 |
无线电 | 2篇 |
一般工业技术 | 7篇 |
冶金工业 | 656篇 |
原子能技术 | 5篇 |
自动化技术 | 3篇 |
出版年
2016年 | 1篇 |
2015年 | 1篇 |
2013年 | 5篇 |
2012年 | 1篇 |
2010年 | 2篇 |
2009年 | 3篇 |
2008年 | 2篇 |
2005年 | 1篇 |
2004年 | 4篇 |
2003年 | 4篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 23篇 |
1998年 | 202篇 |
1997年 | 116篇 |
1996年 | 79篇 |
1995年 | 48篇 |
1994年 | 31篇 |
1993年 | 35篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 6篇 |
1989年 | 6篇 |
1988年 | 8篇 |
1987年 | 5篇 |
1986年 | 12篇 |
1985年 | 7篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 2篇 |
1978年 | 3篇 |
1977年 | 15篇 |
1976年 | 33篇 |
1975年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有691条查询结果,搜索用时 62 毫秒
91.
P Hanutsaha DR Guyer LA Yannuzzi A Naing JS Slakter JS Sorenson RF Spaide KB Freund M Feinsod DA Orlock 《Canadian Metallurgical Quarterly》1998,105(9):1632-1636
OBJECTIVE: Recent studies have shown that indocyanine-green videoangiography (ICG-V) is useful to image occult choroidal neovascularization. The authors studied the ICG-V findings in fellow drusen eyes of patients with unilateral exudative age-related macular degeneration (AMD). The authors also studied the occurrence of exudative changes to determine whether ICG-V is useful in predicting future exudative changes in these eyes with only drusen. DESIGN: Cohort study. PARTICIPANTS: The authors studied 432 consecutive patients diagnosed with unilateral exudative AMD in whom the fellow eye had only drusen by clinical fundus examination and fluorescein angiography. All of these eyes had ICG-V performed. Follow-up data were obtained in all eyes with abnormal indocyanine-green (ICG) angiograms and randomly sampled ICG angiograms of normal eyes. MAIN OUTCOME MEASURES: The initial ICG findings were classified as showing normal or abnormal hyperfluorescence. Abnormal hyperfluorescence eyes were subdivided into focal spots (focal areas of hyperfluorescence < 1 disc area in size) and plaques (areas of hyperfluorescence > 1 disc area). The development of exudative changes in eyes with normal and abnormal hyperfluorescence was compared. RESULTS: Of the 432 fellow eyes, 386 (89%) eyes with drusen had a normal ICG-V study, whereas 46 (10 focal spots and 36 plaques) (11%) eyes had an abnormal ICG-V. Exudative changes occurred in 6 (10%) of 58 normal ICG eyes and 9 (24%) of 38 eyes with abnormal ICG findings during a mean follow-up period of 21.7 months. The difference between drusen eyes with normal ICG angiograms and those with plaques on ICG-V regarding future exudative changes (10% vs. 27%, respectively) was statistically significant (P = 0.038). CONCLUSIONS: Abnormal ICG findings were found in 11% of eyes with clinically and fluorescein angiographically nonsuspicious drusen. The subgroup of patients with plaques on ICG-V had a higher chance of having exudative changes develop. Indocyanine-green videoangiography may be a predictive indicator of future exudative changes in eyes with drusen. A much larger prospective study seems justified. 相似文献
92.
DJ Dairaghi KS Soo ER Oldham BA Premack T Kitamura KB Bacon TJ Schall 《Canadian Metallurgical Quarterly》1998,160(1):426-433
The chemokine RANTES induces a unique biphasic cytoplasmic Ca2+ signal in T cells. The first phase of this signal, similar to that of other chemokines, is G-protein mediated and chemotaxis associated. The second phase of this signal, unique to RANTES and evident at concentrations greater than 100 nM, is tyrosine kinase linked and results in a spectrum of responses similar to those seen with antigenic stimulation of T cells. We show here that certain jurkat T cells responded to RANTES solely through this latter pathway. A direct correlation between the RANTES-induced second phase response and CD3 expression was demonstrated in these cells. Sorting the Jurkat cells into CD3(high) and CD3(low) populations revealed that only the CD3(high) cells were responsive to RANTES. Furthermore, stimulation of these Jurkat cells with anti-CD3 mAb significantly depresses their subsequent response to RANTES. While a RANTES-specific chemokine receptor is expressed at a low level on these Jurkat cells, the RANTES-induced activation is dependent on the presence of the TCR. Thus, stimulation through TCR may partially account for RANTES' unique pattern of signaling in T cells. 相似文献
93.
A Roepstorff O Nilsson A Oksanen B Gjerde SH Richter E Ortenberg D Christensson KB Martinsson PC Bartlett P Nansen L Eriksen O Helle S Nikander K Larsen 《Canadian Metallurgical Quarterly》1998,76(4):305-319
In Denmark (DK), Finland (FIN), Iceland (I), Norway (N), and Sweden (S), 516 swine herds were randomly selected in 1986-1988. Individual faecal analyses (mean: 27.9 per herd) from eight age categories of swine showed that Ascaris suum, Oesophagostomum spp., Isospora suis, and Eimeria spp. were common, while Trichuris suis and Strongyloides ransomi-like eggs occurred sporadically. Large fatteners and gilts were most frequently infected with A. suum with maximum prevalences of 25-35% in DK, N and S, 13% in I and 5% in FIN. With the exception of the remarkably low A. suum prevalence rates in FIN, no clear national differences were observed. Oesophagostomum spp. were most prevalent in adult pigs in the southern regions (21-43% in DK and southern S), less common in the northern regions (4-17% adult pigs infected), and not recorded in I. I. suis was common in piglets in DK, I, and S (20-32%), while < 1% and 5% were infected in N and FIN, respectively. Eimeria spp. had the highest prevalences in adult pigs (max. 9%) without clear geographical differences. I. suis and Eimeria spp. were recorded for the first time in I, and I. suis for the first time in N. 相似文献
94.
JH Pruett KB Temeyer WF Fisher PK Beetham SE Kunz 《Canadian Metallurgical Quarterly》1998,35(5):861-871
In this study potential vaccine candidate immunogens were identified and evaluated in a vaccine challenge trial. Calves vaccinated with a partially purified fraction of Psoroptes ovis-soluble proteins had 8 of 14 calves free of palpable lesions 8 wk after a challenge infestation. A self-grooming behavioral response elicited by a pruritic immediate-type allergic reaction was believed to be an effector in protecting the vaccinated calves from a clinical P. ovis infestation. 相似文献
95.
For all teens, the process of moving from childhood to adulthood is challenging. For young people with disabilities, transitioning to independence presents even more challenges. Barriers to successful transition for young people with disabilities include low expectations by parents and other significant people in the community, lack of knowledge of existing career and vocational education services, and lack of self-advocacy skills. This article provides an overview of issues related to transitioning to adult independence and offers suggestions for assessment, planning, and intervention that can help nurses be effective partners with families and other caregivers in transition efforts. Nurses caring for children with disabilities can help families see strengths in their children and develop realistic, developmentally-appropriate expectations for skill development, attitudes, and behaviors that will promote self-sufficiency in adulthood. Nurses can help families think about possibilities for independence and refer families to community resources that can help young people with disabilities pursue postsecondary education, obtain and maintain jobs, and live independently. 相似文献
96.
AM Mayer PB Jacobson W Fenical RS Jacobs KB Glaser 《Canadian Metallurgical Quarterly》1998,62(26):PL401-PL407
Pseudopterosin E (PSE), a C-10 linked fucose glycoside and pseudopterosin A (PSA), a C-9 xylose glycoside isolated from the marine gorgonian Pseudopterogorgia elisabethae were both effective in reducing PMA-induced mouse ear edema when administered topically (ED50 (microg/ear) PSE(38), PSA(8)) or systemically (ED50 (mg/kg, i.p.) PSE (14), PSA (32)). Both compounds exhibited in vivo analgesic activity in phenyl-p-benzoquinone-induced writhing (ED50 (mg/kg, i.p.) PSE(14), PSA(4). PSE inhibited zymosan-induced writhing (ED50 = 6 mg/kg, i.p.), with a concomitant dose-dependent inhibition of peritoneal exudate 6-keto-prostaglandin F1alpha (ED50 = 24 mg/kg) and leukotriene C4 (ED50 = 24 mg/kg). In vitro, the pseudopterosins were inactive as inhibitors of phospholipase A2, cyclooxygenase, cytokine release, or as regulators of adhesion molecule expression. PSA inhibited prostaglandin E2 and leukotriene C4 production in zymosan-stimulated murine peritoneal macrophages (IC50 = 4 microM and 1 microM, respectively); however, PSE was much less effective. These data suggest that the pseudopterosins may mediate their anti-inflammatory effects by inhibiting eicosanoid release from inflammatory cells in a concentration and dose-dependent manner. 相似文献
97.
JB Thomas MJ Fall JB Cooper RB Rothman SW Mascarella H Xu JS Partilla CM Dersch KB McCullough BE Cantrell DM Zimmerman FI Carroll 《Canadian Metallurgical Quarterly》1998,41(26):5188-5197
A three-component library of compounds was prepared in parallel using multiple simultaneous solution-phase synthetic methodology. The compounds were biased toward opioid receptor antagonist activity by incorporating (+)-(3R,4R)-dimethyl-4-(3-hydroxyphenyl)piperidine (a potent, nonselective opioid pure antagonist) as one of the monomers. The other two monomers, which included N-substituted or unsubstituted Boc-protected amino acids and a range of substituted aryl carboxylic acids, were selected to add chemical diversity. Screening of these compounds in competitive binding experiments with the kappa opioid receptor selective ligand [3H]U69,593 led to the discovery of a novel kappa opioid receptor selective ligand, N-?(2'S)-[3-(4-hydroxyphenyl)propanamido]-3'-methylbutyl?-(3R, 4R)-dimethyl-4-(3-hydroxyphenyl)piperidine (8, RTI-5989-29). Additional structure-activity relationship studies suggested that 8 possesses lipophilic and hydrogen-bonding sites that are important to its opioid receptor potency and selectivity. These sites appear to exist predominantly within the kappa receptor since the selectivity arises from a 530-fold loss of affinity of 8 for the mu receptor and an 18-fold increase in affinity for the kappa receptor relative to the mu-selective ligand, (+)-N-[trans-4-phenyl-2-butenyl]-(3R, 4R)-dimethyl-4-(3-hydroxyphenyl)piperidine (5a). The degree of selectivity observed in the radioligand binding experiments was not observed in the functional assay. According to its ability to inhibit agonist stimulated binding of [35S]GTPgammaS at all three opioid receptors, compound 8 behaves as a mu/kappa opioid receptor pure antagonist with negligible affinity for the delta receptor. 相似文献
98.
The cerebral cortex of anaesthetised 2- to 12-day-old rats was superfused with artificial cerebrospinal fluid containing 100 mM acetate substituted for chloride to condition the brain for spreading depression (SD). After such superfusion, the earliest SD-like events were found at day 9 and full blown SD at day 10, whereas in the unconditioned brain the first SD occurred between days 12 and 15. Acetate conditioning of the cerebral cortex may be used to unmask neuronal and glial properties that are hidden in early stages of development. 相似文献
99.
BACKGROUND: There is a need to evaluate the effectiveness of laryngeal fracture repair using rigid adaptation plates. METHODS: A retrospective chart review of patients undergoing open repair of laryngeal fractures using metal alloy plates, from 1987 to 1995, was performed. Postoperative airway, deglutition, and voice were assessed. Postoperative follow-up ranged from 1 to 58 months (median, 27 months). All 10 patients sustained blunt or penetrating laryngeal trauma. After patients were resuscitated according to the ABC principles recommended by the American College of Surgeons, each underwent open repair of laryngeal fractures using rigid adaptation plates. RESULTS: Outcome was measured by perceptual analysis of the postoperative airway, swallowing, and voice, as well as biocompatibility. Ten patients underwent repair and stabilization of the larynx using adaptation plates. Nine patients sustained blunt trauma, and one patient sustained penetrating trauma. Voice was subjectively graded as good if it resembled the preinjury status, fair if it differed, and poor if it represented aphonia, whisper, or unintelligible speech. Airway was graded as good if it resembled preinjury status, fair if mild exercise intolerance or aspiration existed, and poor if the patient could not be decannulated. Nine patients had a good airway following repair, and six of seven patients requiring tracheotomy were decannulated. All patients tolerated the plates well and suffered no surgical complications. CONCLUSION: Repair of the laryngeal framework using adaptation plates provides adequate, immediate stabilization with restoration of function and is an alternative to traditional methods of repair. 相似文献
100.
EE Mel'nikov KB Tsirul'nikov FS Rasulova LM Ginodman TV Rotanova 《Canadian Metallurgical Quarterly》1998,24(8):638-640
A new efficient substrate, Suc-Phe-Leu-Phe-SBzl, was proposed for studying the function of the Escherichia coli ATP-dependent Lon protease and its modified forms. The kinetic parameters of hydrolysis of the substrate were determined. The esterase activity of protease Lon was found to be nucleotide-regulated. 相似文献