全文获取类型
收费全文 | 1327篇 |
免费 | 0篇 |
专业分类
化学工业 | 5篇 |
轻工业 | 2篇 |
无线电 | 3篇 |
冶金工业 | 1317篇 |
出版年
2021年 | 1篇 |
2010年 | 1篇 |
2006年 | 1篇 |
2004年 | 1篇 |
2003年 | 5篇 |
2000年 | 2篇 |
1999年 | 47篇 |
1998年 | 444篇 |
1997年 | 214篇 |
1996年 | 154篇 |
1995年 | 97篇 |
1994年 | 66篇 |
1993年 | 78篇 |
1992年 | 9篇 |
1991年 | 7篇 |
1990年 | 13篇 |
1989年 | 15篇 |
1988年 | 8篇 |
1987年 | 20篇 |
1986年 | 11篇 |
1985年 | 8篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 7篇 |
1980年 | 13篇 |
1978年 | 2篇 |
1977年 | 33篇 |
1976年 | 59篇 |
1975年 | 3篇 |
排序方式: 共有1327条查询结果,搜索用时 15 毫秒
61.
The effects of transdermal nicotine-assisted smoking cessation on digital perfusion and health-related quality of life were assessed in 10 chronic smokers. Components of digital blood flow were evaluated by digital temperature and laser Doppler fluxmetry before, during, and after a standardized cold challenge. Nutritional flow was measured by vital capillaroscopy; a quantitative perfusion profile was obtained by laser Doppler perfusion imaging. A battery of validated measures were used to evaluate health-related quality of life. The microvascular response of smokers was evaluated before smoking cessation and at 2 and 7 days after smoking cessation and was compared with the response of nonsmoking controls. Results demonstrated that a (1) cutaneous microvascular perfusion was lower in smokers than nonsmokers, (2) the acute administration of transdermal nicotine did not decrease cutaneous perfusion, (3) smoking cessation and transdermal nicotine normalized digital microvascular perfusion by 7 days, and (4) transdermal nicotine and smoking cessation did not negatively impact health-related quality of life. 相似文献
62.
CA Arndt AG Nascimento G Schroeder PJ Schomberg JP Neglia SF Sencer TL Silberman CL Moertel JK Tillisch JS Miser 《Canadian Metallurgical Quarterly》1998,34(8):1224-1229
Over 50% of patients with newly diagnosed rhabdomyosarcoma (RMS) are in the 'intermediate risk' group with a 3-year progression-free survival of approximately 65%. This group consists of stage 1, group III, non-orbit tumours; stage 2, group II and III; and all stage 3 patients utilising the Intergroup Rhabdomyosarcoma Study (IRS) staging system. The role of doxorubicin in the treatment of RMS has been controversial. Ifosfamide, both alone and in combination with etoposide, has significant activity in patients with RMS. The aim of this pilot study was to examine the efficacy and toxicity of a chemotherapy regimen of alternating cycles of vincristine/doxorubicin/cyclophosphamide and etoposide/ifosfamide for intermediate risk RMS. 30 patients with intermediate risk RMS or undifferentiated sarcoma (US) were treated with alternating cycles of vincristine/doxorubicin/cyclophosphamide (VDC) and etoposide/ifosfamide (EI) at planned intervals of 3 weeks. Local treatment of the tumour in most cases was performed after four cycles of chemotherapy, followed by an additional 10 cycles of chemotherapy. At a median follow-up of 37.5 months, the Kaplan-Meier estimate of 3-year event-free survival was 85% (95% confidence interval 72-99%). The overall survival at 3 years was 91% (95% confidence interval 80-100%). No patient died from toxicity. The most common toxicity was febrile neutropenia in 35% of VDC and 26% of EI cycles. No nephrotoxicity or cardiac toxicity was seen. No patient progressed prior to week 12 local therapy. Alternating cycles of VDC and EI are an effective treatment for patients with intermediate risk RMS and US. Toxicity is tolerable. Delaying local treatment until week 12 does not compromise outcome. 相似文献
63.
Time-resolved absorption difference spectra of membrane suspensions of bovine rhodopsin at pH 5, 6, 7, 8, 9, and 10 were collected in the time range from 1 micro s to 200 ms after laser photolysis with 7-ns pulses of 477-nm light. The data were analyzed using singular value decomposition (SVD) and global exponential fitting. At pH 7 the data agree well with previously obtained data (Thorgeirsson et al. (1993) Biochemistry 32, 13861-13872) with fits improved at all pH's by inclusion of a small component due to an absorbance change caused by rotational diffusion which is detectable even at magic angle polarization. A "square scheme" suggested to best explain the previous data, which involves two branches following decay of the lumi intermediate with pathways (1) lumi --> MI480 right harpoon over left harpoon MII and (2) lumi right harpoon over left harpoon MI380 --> MII, could be confirmed throughout the entire pH range. However, to account for the increased rate of the MII --> MI480 reaction in path 1 for rising pH values, we propose that the MII in the square scheme consists of deprotonated MII and protonated MIIH+ forms in rapid equilibrium with each other, resulting in an extended square scheme and increasing the number of 380-nm products from two to three. In addition to the kinetic processes described by the extended square scheme, above pH 8 fast ( approximately 10 micro s) and slow ( approximately 50 ms) components were found. The fast component was assigned to the decay of a blue-shifted lumi intermediate, and the slow component, resolvable only at pH 10, was assigned to formation of a 450 nm absorbing photoproduct. 相似文献
64.
L Pal L Leykin JL Schifren KB Isaacson YC Chang N Nikruil Z Chen TL Toth 《Canadian Metallurgical Quarterly》1998,13(7):1837-1840
A case series of eight cycles of in-vitro fertilization (IVF) in five women diagnosed with malignant disorders is presented. These patients chose to defer definitive treatment for a chance for preservation of potential fertility. The response of these patients to ovarian stimulation, and the outcome, was compared with 17 IVF cycles in 12 age-matched patients with isolated tubal infertility. An apparent adverse influence of malignant disease on the quality and behaviour of oocytes was observed. Despite a comparable total number of oocytes per cycle in the two groups, a significantly reduced percentage of mature oocytes was retrieved per cycle from patients with malignant diseases. The oocytes from patients with malignant disorders were of a poorer quality and exhibited a significantly impaired fertilization rate compared to the controls. We propose that neoplastic processes, irrespective of the site or cell of origin, may have a detrimental impact on the biology of oocytes, an effect akin to that seen on spermatozoa in men with certain malignancies. 相似文献
65.
KR Beutner SK Tyring KF Trofatter JM Douglas S Spruance ML Owens TL Fox AJ Hougham KA Schmitt 《Canadian Metallurgical Quarterly》1998,42(4):789-794
Genital human papillomavirus infection is one of the most common sexually transmitted diseases. Imiquimod is a new agent, an immune-response modifier, that has been demonstrated to have potent in vivo antiviral and antitumor effects in animal models. The present prospective, multicenter, double-blind, randomized, vehicle-controlled trial evaluated the efficacy and safety of daily patient-applied imiquimod for up to 16 weeks for the treatment of external genital warts. Wart recurrence was investigated during a 12-week treatment-free follow-up period. In the intent-to-treat analysis, baseline warts cleared from 49 of 94 (52%) patients treated with 5% imiquimod cream, 13 of 90 (14%) patients treated with 1% imiquimod cream, and 3 of 95 (4%) vehicle-treated patients; the differences between the groups treated with vehicle and imiquimod were significant (P < 0.0001). For subjects who completed the follow-up period, recurrence rates after a complete response were 19% (9 of 48 patients) in the 5% imiquimod cream group, 17% (2 of 12) in the 1% imiquimod cream group, and 0% (0 of 3) in the vehicle-treated group. There were no systemic reactions, although local skin reactions (generally of mild or moderate severity) were common, particularly in the 5% imiquimod cream group. Local reactions caused two patients to discontinue treatment. The most frequently reported local skin reactions were erythema, excoriation or flaking, and erosion. Patient-applied 5% imiquimod cream is effective for the treatment of external genital warts and has a favorable safety profile. 相似文献
66.
Bulimia nervosa is characterized by binge eating and inappropriate compensatory behaviors, such as vomiting, fasting, excessive exercise and the misuse of diuretics, laxatives or enemas. Although the etiology of this disorder is unknown, genetic and neurochemical factors have been implicated. Bulimia nervosa is 10 times more common in females than in males and affects up to 3 percent of young women. The condition usually becomes symptomatic between the ages of 13 and 20 years, and it has a chronic, sometimes episodic course. The long-term outcome has not been clarified. Other psychiatric conditions, including substance abuse, are frequently associated with bulimia nervosa and may compromise its diagnosis and treatment. Serious medical complications of bulimia nervosa are uncommon, but patients may suffer from dental erosion, swollen salivary glands, oral and hand trauma, gastrointestinal irritation and electrolyte imbalances (especially of potassium, calcium, sodium and hydrogen chloride). Treatment strategies are based on medication, psychotherapy or a combination of these modalities. 相似文献
67.
The aim of this work was to develop sustained local release systems for radioiodinated iodo-2'-deoxyuridine (125IUdR) from biodegradable polymeric microspheres to facilitate the controlled delivery of 125IUdR to brain tumours. The selective uptake of IUdR into the cell nucleus results in cell disruption over the short range of the low energy Auger electrons. The biodegradable microspheres can be precisely implanted in the brain by stereotactic techniques and the IUdR within the microspheres is protected from degradation and thus a sustained source of radiolabelled IUdR is available in the vicinity of the residual tumour cells. Poly(lactic-co-glycolic acid), PLGA (85:15), microspheres containing cold IUdR and the Auger-electron emitter 125I, as 125IUdR were prepared using the O/W, O/O and W/O/W emulsion-solvent evaporation methods. The W/O/W emulsion method was most effective in achieving good drug loading with the use of bovine plasma in the internal water phase. Also effective in improving the drug loading was the use of 20% acetone in the dichloromethane and the presence of Span 40 in the organic phase. Electrolytes (NaCl and IUdR) in the external aqueous phase also improved drug loading. After an initial rapid release from the microspheres, a sustained release was observed over 15 days for the 'cold' IUdR. The sustained release portions of the release curves showed Higuchi (t1/2), diffusion controlled release kinetics. The radiolabelled IUdR microspheres showed a burst release effect of 30-40% followed by a sustained release over 35 days. 相似文献
68.
TL Tekirian TC Saido WR Markesbery MJ Russell DR Wekstein E Patel JW Geddes 《Canadian Metallurgical Quarterly》1998,57(1):76-94
The goals of this study were twofold: to determine whether species differences in Abeta N-terminal heterogeneity explain the absence of neuritic plaques in the aged dog and aged bear in contrast to the human; and to compare Abeta N-terminal isoforms in parenchymal vs cerebrovascular Abeta (CVA) deposits in each of the species, and in individuals with Alzheimer disease (AD) vs nondemented individuals. N-terminal heterogeneity can affect the aggregation, toxicity, and stability of Abeta. The human, polar bear, and dog brain share an identical Abeta amino acid sequence. Tissues were immunostained using affinity-purified polyclonal antibodies specific for the L-aspartate residue of Abeta at position one (AbetaN1[D]), D-aspartate at N1 (AbetaN1[rD]), and pyroglutamate at N3 (AbetaN3[pE]) and p3, a peptide beginning with leucine at N17 (AbetaN17[L]). The results demonstrate that each Abeta N-terminal isoform can be present in diffuse plaques and CVA deposits in AD brain, nondemented human, and the examined aged animal models. Though each Abeta N-terminal isoform was present in diffuse plaques, the average amyloid burden of each isoform was highest in AD vs polar bear and dog (beagle) brain. Moreover, the ratio of AbetaN3(pE) (an isoform that is resistant to degradation by most aminopeptidases) vs AbetaN17(L)-x (the potentially nonamyloidogenic p3 fragment) was greatest in the human brain when compared with aged dog or polar bear. Neuritic plaques in AD brain typically immunostained with antibodies against AbetaN1(D) and AbetaN3(pE), but not AbetaN17(L) or AbetaN1(rD). Neuritic deposits in nondemented individuals with atherosclerotic and vascular hypertensive changes could be identified with AbetaN1(D), AbetaN3(pE), and AbetaN1(rD). The presence of AbetaN1(rD) in neuritic plaques in nondemented individuals with atherosclerosis or hypertension, but not in AD, suggests a different evolution of the plaques in the two conditions. AbetaN1(rD) was usually absent in human CVA, except in AD cases with atherosclerotic and vascular hypertensive changes. Together, the results demonstrate that diffuse plaques, neuritic plaques, and CVA deposits are each associated with distinct profiles of Abeta N-terminal isoforms. 相似文献
69.
TS Yeh YY Jan LB Jeng TC Chen TL Hwang MF Chen 《Canadian Metallurgical Quarterly》1998,26(5):1224-1226
We performed a 17-year retrospective analysis of 10 cases of hepatocellular carcinoma presenting as pyogenic liver abscess. Spontaneous tumor necrosis and biliary obstruction caused by tumor thrombi, superimposed with bacterial infection, were the two major pathogeneses. Exact diagnosis of the underlying hepatocellular carcinoma was made for five of the 10 patients before management was attempted. Main clinical manifestations included fever, chills, right-upper-quadrant pain, malaise, anorexia, jaundice, and hepatomegaly. Characteristics such as middle age and male sex, seropositivity for hepatitis B and/or hepatitis C, chronic liver disease, unexplained anemia, marked weight loss, and a severely inversed albumin/globulin ratio raise suspicions about the underlying hepatocellular carcinoma. Management strategies included percutaneous drainage (n = 3), surgical drainage (n = 4), and hepatectomy (n = 3) in addition to administration of parenteral antibiotics in all cases. The prognosis was dismal, with a mean survival of 3.5 months (range, 8 days to 6 months). 相似文献
70.
RM Summers J Andrasko-Bourgeois IM Feuerstein SC Hill EC Jones MK Busse B Wise KE Bove BA Rishforth E Tucker TL Spray JM Hoeg 《Canadian Metallurgical Quarterly》1998,98(6):509-518
Hepatitis C chronically infects approximately 1.5% of Americans and is the most common clinical problem facing hepatologists. Since the virus was initially described in 1989, development of an effective therapy has been challenging. Although several different therapeutic agents have been used, no therapy has been shown to reliably eradicate the virus. Interferon-alpha, a cytokine with immunostimulatory and anti-viral properties, has become the therapy of choice for patients with chronic hepatitis C infection. Trials assessing the efficacy of interferon-alpha have characterized host and viral factors predictive of responses to treatment. A thorough understanding of these predictive factors is requisite to providing cost-effective therapeutic decisions for the patient with chronic hepatitis C infection. 相似文献