全文获取类型
收费全文 | 634篇 |
免费 | 31篇 |
专业分类
电工技术 | 33篇 |
化学工业 | 117篇 |
金属工艺 | 11篇 |
机械仪表 | 15篇 |
建筑科学 | 6篇 |
矿业工程 | 1篇 |
能源动力 | 15篇 |
轻工业 | 68篇 |
水利工程 | 4篇 |
无线电 | 64篇 |
一般工业技术 | 85篇 |
冶金工业 | 184篇 |
原子能技术 | 4篇 |
自动化技术 | 58篇 |
出版年
2023年 | 4篇 |
2022年 | 13篇 |
2021年 | 18篇 |
2020年 | 15篇 |
2019年 | 7篇 |
2018年 | 14篇 |
2017年 | 8篇 |
2016年 | 10篇 |
2015年 | 12篇 |
2014年 | 9篇 |
2013年 | 14篇 |
2012年 | 15篇 |
2011年 | 27篇 |
2010年 | 20篇 |
2009年 | 39篇 |
2008年 | 29篇 |
2007年 | 21篇 |
2006年 | 22篇 |
2005年 | 25篇 |
2004年 | 16篇 |
2003年 | 12篇 |
2002年 | 15篇 |
2001年 | 13篇 |
2000年 | 11篇 |
1999年 | 13篇 |
1998年 | 80篇 |
1997年 | 38篇 |
1996年 | 31篇 |
1995年 | 16篇 |
1994年 | 13篇 |
1993年 | 13篇 |
1992年 | 6篇 |
1991年 | 4篇 |
1990年 | 5篇 |
1989年 | 8篇 |
1988年 | 7篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1981年 | 4篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
排序方式: 共有665条查询结果,搜索用时 15 毫秒
151.
152.
Szapocznik José; Rio Arturo; Murray Edward; Cohen Raquel; Scopetta Mercedes; Rivas-Vazquez Ana; Hervis Olga; Posada Vivian; Kurtines William 《Canadian Metallurgical Quarterly》1989,57(5):571
Structural family therapy, psychodynamic child therapy, and a recreational control condition were compared for 69 six-to-twelve-year-old Hispanic boys who presented with behavioral and emotional problems. The results suggest that the control condition was significantly less effective in retaining cases than the two treatment conditions, which were apparently equivalent in reducing behavioral and emotional problems as well as in improving psychodynamic ratings of child functioning. Structural family therapy was more effective than psychodynamic child therapy in protecting the integrity of the family at 1-year follow-up. Finally, the results did not support basic assumptions of structural family systems therapy regarding the mechanisms mediating symptom reduction. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
153.
Treatment of HIV and related malignancies with pharmacologic and biologic agents has not appreciably modified the course of disease. Immunologic impairment remains the critical factor in response. We report the long-term results of a single session of low-flow (0.3 L/min) extracorporeal perfusion hyperthermia on 29 men and 2 women with disseminated Kaposi's sarcoma and profound immunologic impairment. Any antiretroviral drug employed by the patient was stopped 72 hours prior to treatment and withheld during the period of follow-up. Core temperature was raised to 42 degrees C and held for 1 hour with extracorporeal perfusion and ex vivo blood heating to 49 degrees C as the means of temperature control. Of 31 patients, 2 died of complications secondary to treatment (cardiac arrhythmia; CNS bleed). There were two cases of intravascular coagulopathy. Pressure point skin damage may occur despite adequate cushioning. At 30 days posttreatment complete or partial regressions were seen in 20/29 of those treated, with regressions persisting in 14/29 of those treated by 120 days posttreatment. At 360 days, 4/29 maintain tumor regressions with 1 in complete remission (at 26 months). The patient in complete remission remains culture-negative and PCR-negative for HIV. CD4+ counts rose from around 250 to, and remain around, 800 in this man. Selected healed lesions were biopsied to demonstrate tumor absence. Patients were selected for treatment if pretreatment testing of the tumor showed regression in vitro with heat exposure. Analysis of the early and midterm failures showed little sustained rise of the CD4+ cells if presenting total CD4+ counts were below 50 and had been at such low levels for extended periods, although other surrogate markers of HIV activity declined (semiquantitative PCR) during this period and is felt to support the hypothesis of apoptosis proposed in this illness. Analysis of the tumors of the few men not responding demonstrated elevated levels of IL-6 as compared to responders (12 vs < 1 pg/ml). At 120 days 29/31 patients remained alive (expected, 20). At 360 days, 21/31 remained alive (expected, 11). In no patient was HIV activity stimulated with heat exposure. CMV retinitis did clear in some patients treated (both techniques), but treatment alone did not prevent later development of retinopathy. EBV parameters were markedly altered in the short term with heat exposure in some patients. Few patients showed herpes simplex activation. Varicella-zoster virus remitted in some patients. There is utility in the use of systemic hyperthermia to control HIV and related malignancy.(ABSTRACT TRUNCATED AT 400 WORDS) 相似文献
154.
This cross-sectional study was undertaken to investigate the association of electrocardiographic (ECG) ischemic abnormalities with ischemic heart disease (IHD) risk factors in a Japanese population. Resting ECGs of 1201 subjects (572 men and 629 women, aged 30 to 89 years), were coded independently by two coders according to the Minnesota Code. Blood pressure (BP) was recorded using a standard sphygmomanometer, and non-fasting serum total cholesterol and high-density lipoprotein cholesterol were measured. Codes 1.1 and 1.2 were classified as myocardial infarction and codes 1.3, 4.1-4.4, 5.1-5.3 and 7.1 were classified as ischemia. Prevalence of ECG with evidence of IHD (IHD ECG) was defined as myocardial infarction and ischemia together. Levels of risk factors were compared between subjects with IHD ECGs and those without IHD ECGs. Multiple logistic regression analysis was used to ascertain the associations between IHD ECG and risk factors. The prevalence of myocardial infarction in the total population was 1.5% and 0.7% in men and women, respectively and the prevalence of IHD ECGs was 10% and 11.3% in men and women, respectively. Systolic blood pressure (SBP) was consistently higher in subjects with IHD ECGs in the total population of both sexes (P < 0.001, P = 0.001 for men and women respectively). Diastolic blood pressure (DBP) was higher only in men with IHD ECGs (P = 0.002). In middle-aged men (aged 30-59 years), total cholesterol was considerably higher in subjects with IHD ECGs, although this relationship was statistically not significant. In multiple logistic regression analysis, SBP was independently associated with IHD ECGs in both sexes (P = 0.001). Associations between IHD ECGs with total cholesterol, alcohol intake and smoking were not statistically significant. This study showed that electro-cardiographic IHD evidences in Japanese are predominantly associated with blood pressure level in both sexes. 相似文献
155.
156.
157.
Kuwabara T. Shibuya A. Furuta H. Kita E. Mitsuhashi K. 《Energy Conversion, IEEE Transaction on》1996,11(2):376-384
At 400 MW, the world's largest adjustable speed pumped storage unit for Ohkawachi Power Station, the Kansai Electric Power Co., Inc., Japan, was commissioned on Dec. 3, 1993. It can change power in steps of at least 32 MW in the generate mode and at least 80 MW in the pump mode, within 0.2 s. This paper describes principal design considerations for the control systems of the machine and presents actual performance of the machine with reference to some typical oscillograph charts 相似文献
158.
159.
160.
T Kita 《Canadian Metallurgical Quarterly》1997,86(3):439-443