首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1542篇
  免费   5篇
  国内免费   1篇
电工技术   2篇
化学工业   76篇
金属工艺   4篇
机械仪表   13篇
建筑科学   36篇
能源动力   5篇
轻工业   48篇
水利工程   11篇
无线电   77篇
一般工业技术   147篇
冶金工业   1059篇
原子能技术   4篇
自动化技术   66篇
  2021年   6篇
  2019年   3篇
  2017年   3篇
  2016年   3篇
  2015年   4篇
  2014年   13篇
  2013年   21篇
  2012年   12篇
  2011年   21篇
  2010年   15篇
  2009年   17篇
  2008年   25篇
  2007年   23篇
  2006年   30篇
  2005年   20篇
  2004年   19篇
  2003年   19篇
  2002年   11篇
  2001年   17篇
  2000年   18篇
  1999年   41篇
  1998年   287篇
  1997年   155篇
  1996年   114篇
  1995年   101篇
  1994年   71篇
  1993年   62篇
  1992年   20篇
  1991年   21篇
  1990年   18篇
  1989年   22篇
  1988年   15篇
  1987年   20篇
  1986年   14篇
  1985年   29篇
  1984年   7篇
  1983年   9篇
  1982年   13篇
  1981年   11篇
  1980年   16篇
  1979年   9篇
  1978年   15篇
  1977年   44篇
  1976年   95篇
  1975年   6篇
  1973年   7篇
  1965年   3篇
  1963年   3篇
  1958年   2篇
  1955年   3篇
排序方式: 共有1548条查询结果,搜索用时 17 毫秒
131.
Results are reported for the moisture absorption characteristics of bisphenol epoxy adhesives containing between 8 and 12% rubber particles by weight. The maximum moisture content and the initial rate of absorption were determined for specimens maintained at temperatures of 23 and 60° C in atmospheres with relative humidities of 12, 76 and 100%. The swelling of samples immersed in water was also determined. Unlike many other epoxy systems, the maximum moisture content was found to vary appreciably with temperature, as well as with relative humidity, and the initial rate of absorption was found to decrease substantially with increasing relative humidity, especially at higher temperatures. While the maximum moisture content was essentially independent of rubber content and cure treatment, the initial rate of absorption was found to be sensitive to both factors.  相似文献   
132.
133.
The vast majority of outcome studies examining the effects of marital and family treatments focus exclusively on indicators of and changes in familial functioning and individual members' psychosocial adjustment, but fail to measure, report, or analyze treatment costs, benefits, cost-benefit ratio, or cost-effectiveness. Because of growing concerns about spiraling health care costs, clinical and economic outcomes constitute equally important and complementary aspects of any evaluation of marital and family treatments. The twofold purpose of this article is to define different components of cost analyses of health-related interventions, including marital and family treatments, and to describe methods for calculating and integrating clinical and cost outcome information when evaluating marital and family treatments. There are significant opportunities to promote the use of such treatments by conducting and reporting the results of cost analyses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
134.
OBJECTIVE: To provide recommendations for the treatment of acquired immunodeficiency syndrome-related cytomegalovirus (CMV) end-organ diseases, including retinitis, colitis, pneumonitis, and neurologic diseases. PARTICIPANTS: A 17-member panel of physicians with expertise in clinical and virological research and inpatient care in the field of CMV diseases. EVIDENCE: Available clinical and virological study results. Recommendations are rated according to the quality and strength of available evidence. Recommendations were limited to the treatment of CMV diseases; prophylaxis recommendations are not included. PROCESS: The panel was convened in February 1997 and met regularly through November 1997. Subgroups of the panel summarized and presented available information on specific topics to the full panel; recommendations and ratings were determined by group consensus. CONCLUSIONS: Although the epidemiological features of CMV diseases are changing in the setting of potent, combination antiretroviral therapy, continued attention must be paid to CMV diseases in patients infected with the human immunodeficiency virus to prevent irreversible endorgan dysfunction. The initial and maintenance treatment of CMV retinitis must be individualized based on the characteristics of the lesions, including location and extent, specific patient factors, and characteristics of available therapies among others. Management of relapse or refractory retinitis must be likewise individualized. Ophthalmologic screening for patients at high risk for retinitis or who have a prior diagnosis of extraretinal disease is recommended. Recommendations for gastrointestinal, pulmonary, and neurologic manifestations are included.  相似文献   
135.
FX!32 a profile-directed binary translator   总被引:3,自引:0,他引:3  
A new innovation from Digital allows most x86 Windows applications to run on Alpha platforms with good performance  相似文献   
136.
Solitary endobronchial papillomas in adults are rare neoplasms. Only sporadic cases have been documented. The histologic classification of these tumors remains problematic, and little is known about their clinical behavior. The clinical and pathologic features of 13 endobronchial papillomas and a single endobronchiolar papilloma were reviewed. In situ hybridization for human papillomavirus (HPV) types 6/11, 16/18, and 31/33/51 was performed on seven cases. Twenty-seven additional well-documented cases were identified in a literature review. Human papillomavirus studies were performed in four of the previously reported cases. The 41 neoplasms combined from the Armed Forces Institute of Pathology and literature review were divided into three groups according to their histologic features. Thirty-one of 41 (76%) patients were men. The ages of the patients ranged from 26 to 74 years (median, 57 years). Three morphologically distinct histologic types were recognized; 27 squamous cell papillomas, 7 glandular papillomas, and 7 mixed squamous and glandular papillomas. Squamous papillomas: 23 of 27 (85%) patients were men, and the median age was 54 years. Six of eleven (55%) of these patients smoked. Twenty-six lesions were exophytic and a single lesion had an inverted pattern. Seven of 24 (29%) lesions featured cytologic atypia and 5 of 24 (14%) had viral cytopathic effect. Five of seven (71%) cases examined for HPV DNA were positive. Three of 18 (17%) recurred. Glandular papillomas: Four of seven (57%) patients were women. The mean age was 67 years. One of five (20%) patients smoked. Five lesions were central, and two were peripheral. Four lesions had columnar epithelium, and three had ciliated epithelium. One of six (17%) lesions recurred. Mixed papillomas: five of seven (71%) patients were men. The median age was 64 years. Three of five (60%) patients smoked. Three of seven (43%) lesions featured cytologic atypia. Four of five lesions were examined for HPV DNA and all were negative. No lesions recurred. This study demonstrates that solitary endobronchial papillomas can be separated into three distinct morphologic categories. Squamous cell and mixed papillomas are predominantly lesions of male smokers in their 6th decade. Although cytologic atypia is observed in many cases, the rarity of these tumors and difficulty in separating papillomas from endobronchial papillary squamous carcinomas make generalizations regarding the risk of progression to carcinoma tenuous at best. Human papillomavirus appears to play a pathogenetic role in some squamous cell papillomas, but not in mixed papillomas, yet its presence in the squamous lesions does not correlate with recurrence or malignancy. The first report of an inverted squamous cell papilloma indicates clinical features similar to the more common exophytic squamous cell papillomas. Glandular papillomas, the rarest of all endobronchial papillomas, are found in an older age group than squamous and mixed papillomas, and most-patients are nonsmokers. Based on these findings, all endobronchial papillomas should be completely excised.  相似文献   
137.
PURPOSE: To attempt to safely escalate the dose of radiation for patients with intrahepatic cancer, we designed a protocol in which each patient received the maximum possible dose while being subjected to a 10% risk of radiation-induced liver disease (RILD, or radiation hepatitis) based on a normal tissue complication probability (NTCP) model. We had two hypotheses: H1; with this approach, we could safely deliver higher doses of radiation than we would have prescribed based on our previous protocol, and H2; the model would predict the observed complication probability (10%). PATIENTS AND METHODS: Patients with either primary hepatobiliary cancer or colorectal cancer metastatic to the liver and normal liver function were eligible. We used an NTCP model with parameters calculated from our previous patient data to prescribe a dose that subjected each patient to a 10% complication risk within the model. Treatment was delivered with concurrent hepatic arterial fluorodeoxyuridine (HA FUdR). Patients were evaluated for RILD 2 and 4 months after the completion of treatment. RESULTS: Twenty-one patients completed treatment and were followed up for at least 3 months. The mean dose delivered by the current protocol was 56.6 +/- 2.31 Gy (range, 40.5 to 81 Gy). This dose was significantly greater than the dose that would have been prescribed by the previous protocol (46.0 +/- 1.65 Gy; range, 33 to 66 Gy; P < .01). These data are consistent with H1. One of 21 patients developed RILD. The complication rate of 4.8% (95% confidence interval, 0% to 23.8%) did not differ significantly from the predicted 8.8% NTCP (based on dose delivered) and excluded a 25% true incidence rate (P < .05). This finding supports H2. CONCLUSION: Our results suggest that an NTCP model can be used prospectively to safely deliver far greater doses of radiation for patients with intrahepatic cancer than with previous approaches. Although the observed complication probability is within the confidence intervals of our model, it is possible that this model overestimates the risk of complication and that further dose escalation will be possible. Additional follow-up and accrual will be required to determine if these higher doses produce further improvements in response and survival.  相似文献   
138.
The first known case of an intravascular catheter-related primary cutaneous mucormycosis in a heart transplant patient is reported. The patient had corticosteroid-induced hyperglycemia and experienced an acute tissue rejection episode. A necrotic lesion appeared around the insertion site of a peripheral venous catheter. A biopsy revealed typical mucorales hyphae. The lesion continued to spread during the following 24 hours and necessitated amputation of the forearm. The organism was identified as a Mucor species.  相似文献   
139.
Posterior lenticonus is a protrusion of the posterior capsule and cortex into the vitreous. The etiology is widely debated because of the rare nature of the condition. Lenticonus can present with concurrent ocular conditions, which can disrupt normal visual development. Currently, the only treatment option for posterior lenticonus is lensectomy, which may still have a reduced chance of visual success secondary to the associated disease. Although strabismus and amblyopia are commonly associated, keratoconus has not previously been reported with unilateral posterior lenticonus. Considering treatment of the associated condition may allow the patient to delay or forego surgical intervention.  相似文献   
140.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号