全文获取类型
收费全文 | 24896篇 |
免费 | 1284篇 |
国内免费 | 38篇 |
专业分类
电工技术 | 166篇 |
综合类 | 26篇 |
化学工业 | 6083篇 |
金属工艺 | 475篇 |
机械仪表 | 465篇 |
建筑科学 | 828篇 |
矿业工程 | 45篇 |
能源动力 | 980篇 |
轻工业 | 4694篇 |
水利工程 | 214篇 |
石油天然气 | 138篇 |
武器工业 | 2篇 |
无线电 | 1055篇 |
一般工业技术 | 3436篇 |
冶金工业 | 4047篇 |
原子能技术 | 191篇 |
自动化技术 | 3373篇 |
出版年
2024年 | 48篇 |
2023年 | 201篇 |
2022年 | 645篇 |
2021年 | 824篇 |
2020年 | 492篇 |
2019年 | 599篇 |
2018年 | 710篇 |
2017年 | 721篇 |
2016年 | 796篇 |
2015年 | 673篇 |
2014年 | 911篇 |
2013年 | 1714篇 |
2012年 | 1335篇 |
2011年 | 1712篇 |
2010年 | 1305篇 |
2009年 | 1312篇 |
2008年 | 1132篇 |
2007年 | 994篇 |
2006年 | 825篇 |
2005年 | 709篇 |
2004年 | 664篇 |
2003年 | 596篇 |
2002年 | 532篇 |
2001年 | 374篇 |
2000年 | 374篇 |
1999年 | 406篇 |
1998年 | 1436篇 |
1997年 | 915篇 |
1996年 | 674篇 |
1995年 | 370篇 |
1994年 | 327篇 |
1993年 | 318篇 |
1992年 | 121篇 |
1991年 | 115篇 |
1990年 | 84篇 |
1989年 | 111篇 |
1988年 | 90篇 |
1987年 | 82篇 |
1986年 | 65篇 |
1985年 | 101篇 |
1984年 | 65篇 |
1983年 | 52篇 |
1982年 | 54篇 |
1981年 | 56篇 |
1980年 | 59篇 |
1979年 | 33篇 |
1977年 | 94篇 |
1976年 | 185篇 |
1975年 | 29篇 |
1973年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
141.
The authors suggest that academic institutions build business-oriented policies and practices into the development of any nurse-run clinic to set the stage for financial independence when special or development funding ends. One university-affiliated program that provides 4,000 to 5,000 annual visits drastically changed its strategies when threatened with closure after free rent and other subsidies were withdrawn. The growing emphasis on ambulatory care roles for nurses at all levels makes such clinics critical to the success of the broad-based curricula of nursing education programs, as well as the clinic's value to communities they serve. Funding difficulties frequently threaten the existence of such nurse-run clinics once the initial grant funding is no longer available. This has caused a new emphasis on running such clinics in a business-wise manner. Among the strategies initiated were: direct full-pay at the time of service; a realistic business management plan; aggressive planned marketing; contracts and agreements with other agencies; obtaining provider status with selected HMOs. 相似文献
142.
J Sánchez A Torres J Serrano J Román C Martín L Pérula F Martínez P Gómez 《Canadian Metallurgical Quarterly》1997,20(5):403-408
BACKGROUND: Locally advanced thyroid cancer invading the tracheal cartilage represents a difficult treatment dilemma during thyroidectomy. METHODS: A retrospective chart review was performed to determine the results of laryngotracheal resection or tracheal cartilage shave with adjuvant radiotherapy in patients with locally advanced thyroid cancer invading the upper airway. RESULTS: Of 597 patients undergoing thyroidectomy for thyroid cancer, 40 were found to have laryngotracheal invasion. Thirty-five patients with superficial invasion underwent cartilage shave procedures with adjuvant radiotherapy; five with full-thickness invasion underwent radical resection, including tracheal sleeve resection (n = 3) or total laryngectomy (n = 2). Histologic subtypes included papillary (n = 32), follicular (n = 2), Hurthle cell (n = 1), medullary (n = 3), and anaplastic (n = 2). Of the cartilage shave group, 25 are currently alive with no evidence of disease at a mean follow-up of 81 months (range 1-290). Six developed isolated local/regional recurrence and were managed with total laryngectomy (n = 1), tracheal resection (n = 1), cervical lymphadenectomy (n = 1), or repeat radiotherapy (n = 3). All six patients remain free of disease at a mean follow-up of 5 years. Of those who underwent initial laryngotracheal resection, four remain free of disease at a mean follow-up of 5 years. The rates of 10-year disease-free survival and overall survival for all patients were 47.9% (95% confidence interval [CI] 24.8, 71.0) and 83.9% (95% CI 70.3, 97.5), respectively. CONCLUSIONS: These data suggest that adequate management of thyroid cancer with laryngotracheal invasion can be achieved with a more conservative surgical approach and adjuvant radiotherapy, reserving more radical resections for extensive primary lesions or locally recurrent disease. 相似文献
143.
144.
145.
146.
E García R Calvo JM Rodríguez-Sasiaín R Jiménez IF Trocóniz E Suárez 《Canadian Metallurgical Quarterly》1995,39(8):1019-1023
The influence of altered protein binding on the neuromuscular effect of atracurium has been studied in rats with experimental inflammation induced by subcutaneous injection of turpentine oil. Doses of atracurium ranging from 0.45 to 1.5 mg.kg-1 were administered to control (n = 30) and to experimental inflammation induced rats (n = 30). Neuromuscular transmission was monitored by recording the twitch tension of the tibialis-anterior muscle elicited by stimulation of the sciatic nerve. Three effect parameters were recorded: (i) intensity of the effect, measured as percentage depression of baseline twitch tension, (ii) duration of drug action (min) and (iii) recovery time (min). The dose-intensity of the effect relationship was modelled using a sigmoid Emax model. The ED50 (effective dose eliciting 50% of the maximum effect) was significantly increased (P < 0.01) in the inflammation group as compared to the control group (0.94 vs. 0.68 mg.kg-1). This change was reflected in a shift of the dose-response curve to the right in the pretreated rats. For equipotent doses ED95 (defined as the effective dose eliciting 95% of maximum effect), no differences were found in recovery time and duration of action between the two groups of rats. Mucoproteins levels (index of alpha 1-acid glycoprotein (AAG) and protein binding were significantly increased in rats with experimental inflammation as compared to control rats. Based on these results, altered serum protein binding of atracurium appears to be responsible, at least in part, for the resistance to atracurium. 相似文献
147.
An analysis using maximum power-density criteria has been carried out for an endoreversible Carnot heat engine. The results have been compared with known results on maximum power analysis. The design parameters at maximum power density lead to smaller and more efficient endoreversible Carnot heat engines than those working at maximum power output. 相似文献
148.
Male Wistar rats given a single moderate dose (1.7 mg/kg, IP) of pentobarbital (PB), followed by six trials on the moving belt apparatus during the next hour, showed tolerance to the motor-impairing effects of a second dose of 17 mg/kg given 24 h later. A control group that received saline before the first test showed the usual initial sensitivity when tested with PB 24 h later. Three weeks later, the first group showed cross-tolerance to the effects of ethanol (1.7 g/kg, IP) on the same test, while the second group did not. These findings support the suggestion that rapid tolerance is closely similar to chronic tolerance and that the contribution of intoxicated practice results in a long-lasting component that applies to cross-tolerance to ethanol on the same test. 相似文献
149.
NV Zheleznova SL Mukomolov AB Zhebrun FS Noskov II Malkova EP Shargorodskaia AD Al'tshte?n VA Pliutnikova IN Lavrent'eva NN Ptichnikova 《Canadian Metallurgical Quarterly》1996,(5):49-53
The use of a recombinant poxvirus (RPV) strain, expressing HBsAg in the process of reproduction in different bioreactor systems under stationary and bioreactor conditions of cultivation, made it possible to obtain highly purified HBsAg. The identity and purity of HBsAg was confirmed by the analysis of its amino acid composition, SDS electrophoresis in polyacrylamide gel, electron microscopy and high-performance liquid chromatography. Good prospects of the use of RPV-expressed gene engineering HBsAg as the basis vaccines against hepatitis B was demonstrated in 10 experimental batches of vaccine. All batches of the preparation had pronounced immunogenicity and were safe and nontoxic in animal experiments. The ID50 of experimental batches did not exceed 211 ng/ml, which, according to the data of comparative experiments, was lower than, or equal to, corresponding values of analogous foreign commercial preparations, based on plasma or yeast HBsAg. 相似文献
150.
AJ Dorta M Ferra R Bu-Colfiu L García M Gil X Escobar G Martín NA Díaz OM Perez MT Interián 《Canadian Metallurgical Quarterly》1993,10(10):490-491
It is essential to know how the immune system acts in different neurological diseases, some of them non very well known or of unknown etiology at all. It was applied Reiber and Felgenhauer's formula in 56 patients with different diseases. IgA, IgM, IgG and albumin were quantified in sera and cerebrospinal fluid by simple immunodiffusion. It was observed more frequent IgG local synthesis and IgA in this sample. 相似文献