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   867篇
  免费   39篇
电工技术   13篇
化学工业   181篇
金属工艺   13篇
机械仪表   17篇
建筑科学   34篇
矿业工程   1篇
能源动力   37篇
轻工业   55篇
水利工程   3篇
石油天然气   2篇
无线电   143篇
一般工业技术   150篇
冶金工业   121篇
原子能技术   4篇
自动化技术   132篇
  2023年   10篇
  2022年   5篇
  2021年   28篇
  2020年   16篇
  2019年   14篇
  2018年   20篇
  2017年   18篇
  2016年   31篇
  2015年   32篇
  2014年   44篇
  2013年   56篇
  2012年   40篇
  2011年   58篇
  2010年   41篇
  2009年   39篇
  2008年   48篇
  2007年   45篇
  2006年   37篇
  2005年   26篇
  2004年   34篇
  2003年   32篇
  2002年   17篇
  2001年   17篇
  2000年   12篇
  1999年   8篇
  1998年   30篇
  1997年   25篇
  1996年   10篇
  1995年   10篇
  1994年   5篇
  1993年   14篇
  1992年   3篇
  1991年   5篇
  1990年   8篇
  1989年   4篇
  1988年   6篇
  1987年   4篇
  1986年   5篇
  1985年   4篇
  1984年   2篇
  1983年   3篇
  1982年   3篇
  1980年   4篇
  1979年   2篇
  1977年   4篇
  1976年   15篇
  1975年   3篇
  1973年   2篇
  1972年   2篇
  1968年   1篇
排序方式: 共有906条查询结果,搜索用时 171 毫秒
91.
Arnaud  J.A. 《Electronics letters》1972,8(22):541-542
A confusion is sometimes made in the literature between the mass-carrying momentum of a photon, which is inversely proportional to the refractive index of the medium in which it propagates, and the momentum taken up by an absorber located in a fluid, which is directly proportional to the refractive index of the fluid. The distinction between these two momenta is clarified by considering an artificial dielectric.  相似文献   
92.
Numerical results on polymer surrounded by an air micro-ring coupled to waveguides are presented. The FDTD method predicts a filter width of 1.4 nm and an extraction efficiency of almost 80% for a gap of 0.15 /spl mu/m.  相似文献   
93.
94.
Filters with 100 GHz free spectral range (FSR) and finesse up to 16 are demonstrated over the 1525 to 1583 nm band. The photoinduced birefringence results in a polarisation-dependent spectral response. Finesse and FSR uniformity are addressed  相似文献   
95.
Legal suits against visceral surgeons have increased since the advent of laparoscopic surgery. The duties of physicians have not however changed with the development of laparoscopic techniques. Since the decree promulgated in 1936, physicians have a legal commitment to provide the means required for patient care. This obligation has been recalled in different court judgements and in the new deontology code. In addition, jurisprudence tends more and more towards responsibility without risk. Laparoscopic cholecystectomy is not risk-free. Although morbidity and mortality have not risen with laparoscopic procedures, the types of complications encountered have changed. Reported accidents have become more frequent. The number of suits against surgeons has also increased. Surgeons must therefore be highly prudent and diligent. Precautions concerning personnel management, the choice of material and its upkeep. Special care must be given to the peroperative pneumoperitoneum and the use of monopolar electrocoagulation. A peroperative cholangiogram should be obtained. A careful operative report is very important. The surgeon must be able to justify his competence. Finally, the surgical community should publish more results concerning the rate of complications in order to establish reference material for experts.  相似文献   
96.
97.
The spectrum, Sp(), of a sentence is the set of cardinalities of finite structures which satisfy . We prove that any set of integers which is in Func1, i.e. in the class of spectra of first-order sentences of type containing only unary function symbols, is also in BIN1, i.e. in the class of spectra of first-order sentences of type involving only a single binary relation.

We give similar results for generalized spectra and some corollaries: in particular, from the fact that the large complexity class cNTIMERAM(cn) is included in Func1 for unary languages (n denotes the input integer), we deduce that the set of primes and many “natural” sets belong to BIN1.

We also give some consequences for the image of spectra under polynomials of .  相似文献   

98.
The production, survival and function of monocytes and macrophages are regulated by the macrophage colony-stimulating factor (M-CSF or CSF-1) through its tyrosine kinase receptor Fms. Binding of M-CSF results in Fms autophosphorylation on specific tyrosines that act as docking sites for intracellular signaling molecules containing SH2 domains. Using a yeast two-hybrid screen, we cloned a novel adaptor protein which we called 'Mona' for monocytic adaptor. Mona contains one SH2 domain and two SH3 domains related to the Grb2 adaptor. Accordingly, Mona interacts with activated Fms on phosphorylated Tyr697, which is also the Grb2-binding site. Furthermore, Mona contains a unique proline-rich region located between the SH2 domain and the C-terminal SH3 domain, and is apparently devoid of any catalytic domain. Mona expression is restricted to two hematopoietic tissues: the spleen and the peripheral blood mononuclear cells, and is induced rapidly during monocytic differentiation of the myeloid NFS-60 cell line in response to M-CSF. Strikingly, overexpression of Mona in bone marrow cells results in strong reduction of M-CSF-dependent macrophage production in vitro. Taken together, our results suggest an important role for Mona in the regulation of monocyte/macrophage development as controlled by M-CSF.  相似文献   
99.
We analyzed the influence of clinical and psychological factors on the long-term efficacy of botulinum toxin A (BTX) injections in 45 patients with blepharospasm and 66 patients with hemifacial spasm. Injections efficacy (respectively 94.3% and 95.7%) and duration of relief (respectively 14.8 and 18.7 weeks) remained stable over seven successive injections. Clinical improvement was not influenced by patients' sex, age, or disease duration but by psychological background (p < 0.001). Patients who failed to respond after repetitive injections had lower inter-injections intervals (p < 0.05). This data shows: (1) the importance of psychological contexte in subjective evaluation of treatment efficacy with BTX, (2) emphasizes the necessity of avoiding close injections.  相似文献   
100.
Most of the available industrial schedulers are based on a simulation approach using dispatching rules. These rules are often dedicated to the satisfaction of a single performance criterion, and are used whatever the characteristics of the workshop or of the set of jobs. An approach which allows one to bring in compromises between rules is set out in this paper. These compromises can be parametered in accordance with the objectives of the workshop and the characteristics of the jobs in order to introduce some reactivity in the decision system. Three ways to set up the parameters are compared: experimental design, fuzzy expert system and neural network. The method allowing one to define compromises can be implemented on each scheduler that uses a simulation approach. Tests have been made with an industrial scheduler called SIPAPLUS, the results of which are developed in this paper.  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