首页 | 官方网站   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   677篇
  免费   27篇
  国内免费   2篇
工业技术   706篇
  2023年   6篇
  2021年   5篇
  2020年   6篇
  2019年   6篇
  2018年   10篇
  2017年   11篇
  2016年   10篇
  2015年   10篇
  2014年   15篇
  2013年   20篇
  2012年   13篇
  2011年   24篇
  2010年   19篇
  2009年   23篇
  2008年   24篇
  2007年   17篇
  2006年   21篇
  2005年   14篇
  2004年   22篇
  2003年   25篇
  2002年   16篇
  2001年   18篇
  2000年   18篇
  1999年   29篇
  1998年   78篇
  1997年   46篇
  1996年   33篇
  1995年   29篇
  1994年   20篇
  1993年   19篇
  1992年   15篇
  1991年   6篇
  1990年   4篇
  1989年   5篇
  1988年   3篇
  1987年   7篇
  1986年   6篇
  1985年   5篇
  1984年   5篇
  1983年   7篇
  1982年   9篇
  1980年   2篇
  1979年   3篇
  1978年   4篇
  1977年   5篇
  1976年   5篇
  1973年   1篇
  1972年   2篇
  1968年   1篇
  1962年   1篇
排序方式: 共有706条查询结果,搜索用时 15 毫秒
51.
A patient with malignant cardiac pheochromocytoma with bone metastases is described. The primary tumor was located between the pulmonary trunk and the left atrium, while metastatic lesions were found in the iliac bones. Treatments with antihypertensive agents, alpha-methylparatyrosine, and combination chemotherapy with cyclophosphamide, vincristine, and dacarbazine partially improved the patient's symptoms, catecholamine levels, and the metastatic lesion of the iliac bones. However, the primary tumor in the heart progressively increased in size and the patient died of disseminated intravascular coagulation and other various complications about 4 years after the diagnosis of the disease.  相似文献   
52.
The deformation mechanism in high-strain-rate superplastic P/M7475 before and after continuous dynamic recrystallization (CDRX) was investigated. The recrystallization process in P/M7475 differed from that in conventional superplastic material, I/M7475. In I/M7475, the fine-grained microstructure was obtained by static recrystallization before deformation. On the other hand, the substructure in P/M7475 evolved into fine grains during deformation by CDRX. The percentage of high-angle and random boundaries was low at an initial stage of deformation. However, it increased with strain in P/M7475. The microstructural change in P/M7475 influenced a deformation mechanism and affected grain boundary sliding (GBS). The ratio of contribution of GBS to total elongation was low at an early stage of deformation in P/M7475. However, it increased with deformation progressed. It is suggested that the deformation behavior in P/M7475 changed from dislocation creep to superplasticity as the dominant deformation mechanism changed to GBS. The activation energy for superplastic flow in P/M7475 was close to that for lattice self-diffusion in pure aluminum. It is therefore concluded that the dominant deformation mechanism after CDRX in P/M7475 is GBS accommodated by dislocation movement controlled by lattice self-diffusion, similar to that in I/M7475.  相似文献   
53.
A 44-year-old premenopausal woman having local recurrence and pleural and bone metastases of breast cancer was treated with aromatization inhibition in combination with Luteinizing Hormone-releasing Hormone (LH-RH) agonist. The dominant site of metastasis was a painful local lesion invading the chest wall. A partial response by reducing the size of the local lesion was attained 3 months after initiation of treatment. This result suggested that treatment using aromatization inhibition in combination with LH-RH agonist would be effective in premenopausal breast cancer. To confirm the effectiveness of this treatment, comparative study between aromatization inhibition in combination with LH-RH agonist aromatization inhibition alone and anti-estrogen in combination with LH-RH agonist are needed.  相似文献   
54.
A right-handed 72-year-old man (I.K.) who complained of difficulty identifying familiar faces was investigated on a series of tests of face perception (face matching, recognition of age and sex, and meaning of facial expressions), facial identity (faces of families and famous persons as retrograde ones and his doctor's faces as anterograde ones) and other neuropsychological abilities. His scores of face perception tests were normal or mildly disturbed. His memory performances measured with WMS-R and Rey-Osterrieth figure were normal. But he could identify none of anterograde and retrograde faces and failed to experience any familiarity with those faces. In addition, he could not recognize none of voices of family members and a doctor, despite of being able to recognize about the age and sex of voice. On the other hand, he could describe personalities of his family members and doctors, but knew none of famous people. Memory for personal events in the recent and remote past was well preserved, while that for social events was severely disturbed in both past. In addition to impairment of identification of familiar faces, he had severe problems with identifying famous common buildings and animals. He also presented Gogi (word meaning) aphasia and impairment of semantic memory for some common objects. Tyrrell et al. reported a similar case and McNeil et al. examined the patient on covert recognition of face in detail. On their task, he showed no covert effects and they attributed the result to impairment of face recognition units themselves. Their way of thinking seems to give an explanation of I.K.'s disturbance of anterograde and retrograde memory for faces.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
55.
A 57 years old male consulted our hospital in complaining chest oppression and short of breath. Familial and dilated phase hypertrophic cardiomyopathy (HCM) was detected by ECG, echocardiography, left ventriculography and left ventricular endomyocardial biopsy. 201T1 SPECT showed regional increased accumulation in the ventricular septum, however, no myocardial accumulation of 123I-beta-methyl-p-iodophenylpentadecanoic acid (123I-BMIPP) was observed. We analyzed CD36 in this patient, and found he had type 1 CD36 deficiency. Myocardial uptake of long-chain fatty acids occurs via a specific transporter, which is homologous with human CD36. We hypothesize that CD36 deficiency, especially type 1 CD36 deficiency, might be one factor of no myocardial 123I-BMIPP uptake.  相似文献   
56.
The catalytic activities of Fe-MFI (88% exchange) and Cu-MFI (122% exchange) zeolite catalysts for the decomposition and mainly the selective reduction of nitrous oxide by propene have been studied in the temperature range from 523 to 773 K. In the presence of oxygen and water vapor, both materials reveal strong retardation of their activity. When propene is added as reductant, Fe-MFI showed very high activity even in the low-temperature region and at low propene concentrations, whereas Cu-MFI is strongly deactivated. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
57.
Stimulated Raman gain (SRG) spectroscopy using infrared pump pulses with narrow linewidth and a low-noise cw probe infrared laser was proposed. High-resolution Raman spectra of solutions were obtained. The SRG spectra of crystal GaP, benzene, and toluene were measured to confirm the spectral resolution and sensitivity over the terahertz (THz) region. We discuss the polarization dependence of the spectral measurement of carbon tetrachloride. Our system can detect organic molecules in aqueous solutions.  相似文献   
58.
This paper presents an efficient computational algorithm for selecting the optimal generation mix under uncertain circumstances. Subjective, experiential or linguistic uncertainties are selected from among various uncertainties, i.e., we treat fuzziness in generation expansion planning. The fuzziness can be divided into: (1) the fuzziness of decision making; and (2) the fuzziness of some planning parameters, such as load growth, fuel price, and so on. Both classes of fuzziness are integrated into a fuzzy decision based on fuzzy sets theory, and then the optimal generation mix can be determined by the Fuzzy Dynamic Programming (FDP) technique. The proposed method, which is based on the dynamic programming technique, is extended by using the Bellman-Zadeh maximizing decision. In the method, each generation technology and generation capacity are selected as a stage and state, respectively. The proposed method can easily accommodate not only the fuzziness but also many constraints of generation expansion planning, such as integer solutions of unit capacities, condition of existing units, and so on. Furthermore, the arbitrary shape of membership function can be used. The effectiveness and feasibility of the proposed method are demonstrated on a typical power system model.  相似文献   
59.
60.
Reconstitution of the biosynthetic machinery for fungal secondary metabolites in Aspergillus oryzae provides an opportunity both for stepwise determination of the biosynthetic pathways and the total biosynthesis of fungal natural products. However, to maximize the utility of the reconstitution system, a simple and rapid strategy for the introduction of heterologous genes into A. oryzae is required. In this study, we demonstrated an effective method for introducing multiple genes involved in the biosynthesis of fungal metabolites by using the expression vectors pUARA2 and pUSA2, each of which contains two cloning sites. The successful introduction of all the aflatrem biosynthetic genes (seven genes in total) after two rounds of transformation enabled the total biosynthesis of aflatrem. This rapid reconstitution strategy will facilitate the functional analysis of the biosynthetic machinery of fungal metabolites.  相似文献   
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-23

京公网安备 11010802026262号