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   601篇
  免费   41篇
  国内免费   15篇
电工技术   12篇
综合类   33篇
化学工业   52篇
金属工艺   32篇
机械仪表   32篇
建筑科学   33篇
矿业工程   7篇
能源动力   4篇
轻工业   73篇
水利工程   3篇
石油天然气   7篇
武器工业   3篇
无线电   28篇
一般工业技术   29篇
冶金工业   238篇
原子能技术   15篇
自动化技术   56篇
  2024年   2篇
  2023年   4篇
  2022年   9篇
  2021年   7篇
  2020年   19篇
  2019年   1篇
  2018年   9篇
  2017年   6篇
  2016年   1篇
  2015年   8篇
  2014年   16篇
  2013年   30篇
  2012年   23篇
  2011年   44篇
  2010年   21篇
  2009年   37篇
  2008年   31篇
  2007年   43篇
  2006年   15篇
  2005年   29篇
  2004年   11篇
  2003年   5篇
  2002年   17篇
  2001年   12篇
  2000年   6篇
  1999年   6篇
  1998年   67篇
  1997年   37篇
  1996年   36篇
  1995年   26篇
  1994年   6篇
  1993年   19篇
  1992年   4篇
  1991年   5篇
  1990年   3篇
  1989年   5篇
  1988年   2篇
  1987年   2篇
  1986年   1篇
  1985年   1篇
  1983年   4篇
  1982年   1篇
  1981年   6篇
  1980年   1篇
  1977年   4篇
  1976年   9篇
  1975年   1篇
  1970年   1篇
  1962年   1篇
  1961年   3篇
排序方式: 共有657条查询结果,搜索用时 15 毫秒
101.
The role of ceramide in cell signaling   总被引:1,自引:0,他引:1  
  相似文献   
102.
103.
37 acute schizophrenic inpatients were studied in respect to the therapeutic effect of the body-centered group psychotherapy (k?rperzentrierte Gruppenpsychotherapie). The evaluation was made by the rating of ego functions (Bellak et al., 1973). The acute schizophrenic patients with somatic disturbances (functional ones, body illusions and halluzinations, depersonalisation) turned out to make significantly better progress in ego functions (p less than 0.05) than the control sample.  相似文献   
104.
105.
Electrically heated filaments are frequently used to study catalytic processes. In this respect the phenomenon of propagation of nonlinear thermal waves which separate regions of different temperatures on an iron filament heated by an electrical current in H2 atmosphere has been theoretically and experimentally studied. It has been shown that the character of wave propagation is dependent on the condition of feeding the current. The waves are propagated with constant velocity when the feeding takes place from a stabilized current source, while the velocity is variable when a stabilized voltage source is used. In both cases the formation of non-uniform stable steady states (structures) is possible. In the first case they exist for a unique value of the parameter (current) while for the second case, stable structures are observed for a certain interval of values of the parameter (voltage).  相似文献   
106.
107.
The available nuclear structure information for all nuclei with mass number A=185 is presented. Various decay and reaction data are evaluated and compared. Adopted data, levels, spin, parity, and configuration assignments are given.  相似文献   
108.
A variety of adrenal imaging agents have been used in nuclear medicine, but no agent has been developed for magnetic resonance (MR) imaging. The authors have previously observed accumulation of aminated macromolecules in adrenal glands. They now report the synthesis of a model polymeric aminated contrast agent for enhanced MR imaging of the adrenal glands. The model agent consisted of a poly-L-lysine conjugate (molecular weight, 245 kd) that had 70% free epsilon amino groups and 30% diethylenetriaminepentaacetic acid (DTPA)-derivatized amino groups to bind indium-111 or gadolinium. One hour after intravenous administration of this compound, adrenal uptake was 10.1% +/- 0.7 of injected dose per gram of tissue. When all free epsilon amino groups of the polylysine were completely substituted with DTPA, adrenal uptake was 3.4 times lower, indicating the importance of free amino groups for adrenal uptake. MR imaging in rats showed that a dose of 0.08 mmol of gadolinium per kilogram of the agent was sufficient to enhance the signal intensity of adrenal glands. There hours after intravenous administration of the agent, signal intensity of the adrenal glands was 186% of precontrast values (liver, 165%; kidney, 91%). Fluorescence microscopy showed that the agent accumulated primarily in the cortical zona glomerulosa and in the adrenal medulla. These initial studies demonstrate the feasibility of designing contrast agents for MR imaging of the adrenal glands.  相似文献   
109.
The purpose of this work was two-fold. In the first instance, 1H NMR spectra of the ultracentrifuged lipoprotein fractions (VLDL, LDL and HDL) from six volunteers with different clinical conditions were measured. The methylene regions of the experimental spectra were modelled in the frequency domain using non-linear lineshape fitting analyses. In this way the resolvable Lorentzian component structures of the methylene regions of these lipoprotein fraction spectra could be determined. Second, the lipoprotein fraction analyses were used to construct simplified component structures, which interpreted the lipoprotein fraction spectra well, and were feasible to use in the total plasma spectra analyses. The considerable overlap problem of the resonances was properly handled in this way. The NMR-based relative amounts of the lipoproteins (relative integrated intensities of the lipoprotein model signals) obtained were compared to the biochemically resolved relative molar percentages of the lipoprotein fractions and also of the lipid contents between the lipoprotein complexes. It was noticed that nearly all correlations were extremely good. Thus, it is suggested that the developed methodology could be used as a fast method to predict the relative amounts of the lipoproteins and also possibly the relative lipid contents between the major lipoprotein categories directly from the proton NMR spectrum of a total blood plasma sample. Furthermore, if internal or external reference for the integrated intensities of the proton NMR resonances were used, it should also be possible to obtain the absolute amounts of these quantities.  相似文献   
110.
Nedocromil sodium, a topical antiinflammatory agent recommended as a prophylactic regimen for asthma, is known to inhibit both allergic and nonallergic inflammatory processes in which an essential role for T cells has been implicated. Therefore the direct effects of this drug on several aspects of T-cell activity were analyzed in the present study. By using murine lymphocytes we found that NS at concentrations of 10(-8) to 10(-6) mol/L inhibited the mitogen- or antigen-induced proliferative responses of these cells. It is interesting to note that higher concentrations were ineffective. Preincubation of immune lymph node cells from contact sensitized mice with the drug abrogated their ability to transfer contact sensitivity to naive recipients, an effect that was found to be specific for the treated cells. Nedocromil sodium also interfered with the mitogen-induced interleukin-2 and tumor necrosis factor production by T cells and with their ability to adhere to the bound protein components of the extracellular matrix laminin and fibronectin. All these effects may be attributed to the inhibition of the increase of cytosolic calcium, which accompanies the early phase of T-cell activation and which is an essential step in inducing the aforementioned phenomena.  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