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   1973篇
  免费   4篇
综合类   4篇
化学工业   17篇
金属工艺   15篇
机械仪表   7篇
建筑科学   1篇
矿业工程   6篇
能源动力   5篇
轻工业   130篇
石油天然气   1篇
无线电   9篇
一般工业技术   24篇
冶金工业   1750篇
自动化技术   8篇
  2021年   3篇
  2019年   3篇
  2017年   3篇
  2016年   4篇
  2014年   6篇
  2013年   4篇
  2012年   4篇
  2011年   7篇
  2010年   7篇
  2009年   5篇
  2008年   9篇
  2007年   9篇
  2006年   3篇
  2005年   2篇
  2004年   6篇
  2003年   6篇
  2002年   2篇
  1999年   60篇
  1998年   619篇
  1997年   310篇
  1996年   179篇
  1995年   97篇
  1994年   83篇
  1993年   111篇
  1992年   17篇
  1991年   18篇
  1990年   25篇
  1989年   29篇
  1988年   20篇
  1987年   15篇
  1986年   27篇
  1985年   9篇
  1983年   3篇
  1982年   4篇
  1981年   16篇
  1980年   13篇
  1978年   5篇
  1977年   32篇
  1976年   74篇
  1967年   4篇
  1907年   6篇
  1906年   8篇
  1905年   15篇
  1904年   16篇
  1903年   14篇
  1902年   7篇
  1901年   14篇
  1900年   9篇
  1899年   12篇
  1898年   12篇
排序方式: 共有1977条查询结果,搜索用时 31 毫秒
81.
In Biomphalaria glabrata with a strong natural resistance, Schistosoma mansoni sporocysts are rapidly encapsulated by granulocytes and killed, mainly by the strong phagocytic activity of the cells. Irradiated Echinostoma paraensei sporocysts seem able to suppress the function of the granulocytes. Tissue reactions in snails with self-cure demonstrate: involvement of two types of cells, granulocytes and hyalinocyte-like cells; formation of amoeba-fibrous capsules; limited tendency of granulocytes to become attracted to the parasites; a slow process of parasite destruction; and a possible involvement of humoral factors. It seems that there is partial suppression of the granulocyte function in smails with self-cure.  相似文献   
82.
    
Ohne ZusammenfassungTeil einer Dissertationsarbeit vonR. Pires. Techn. Universität München.  相似文献   
83.
84.
This paper presents a simulation-based planning software for high complexity production settings which currently undergoes first real-data industry application tests in commercial vehicle assembly. The system will also be applicable in other industries with a sufficiently high number of products and variants. The solution enables the forecasting of required personnel and temporary additional workers (“floaters”) for every cycle at the production line. It periodically collects process times, sequence and feature data for the vehicles. The cumulated workload is calculated under consideration of flexibilities. A web-based user interface enables to set and change reference data, define process simulations and to compile diagrams and charts for the analysis of the results of the different simulation runs. Various filters as to time periods, vehicle types or feature variants allow the planner a target-oriented analysis and provide feedback for improving production line tacting. Finally, some qualitative results of a first industry test in commercial vehicle assembly give feedback about the usability of existing analytical features and desirable additional features.  相似文献   
85.
86.
The CTFA Evaluation of Alternatives Program is an evaluation of the relationship between data from the Draize primary eye irritation test and comparable data from a selection of promising in vitro eye irritation tests. In Phase III, data from the Draize test and 41 in vitro endpoints on 25 representative surfactant-based personal care formulations were compared. As in Phase I and Phase II, regression modelling of the relationship between maximum average Draize score (MAS) and in vitro endpoint was the primary approach adopted for evaluating in vitro assay performance. The degree of confidence in prediction of MAS for a given in vitro endpoint is quantified in terms of the relative widths of prediction intervals constructed about the fitted regression curve. Prediction intervals reflect not only the error attributed to the model but also the material-specific components of variation in both the Draize and the in vitro assays. Among the in vitro assays selected for regression modeling in Phase III, the relationship between MAS and in vitro score was relatively well defined. The prediction bounds on MAS were most narrow for materials at the lower or upper end of the effective irritation range (MAS = 0-45), where variability in MAS was smallest. This, the confidence with which the MAS of surfactant-based formulations is predicted is greatest when MAS approaches zero or when MAS approaches 45 (no comment is made on prediction of MAS > 45 since extrapolation beyond the range of observed data is not possible). No single in vitro endpoint was found to exhibit relative superiority with regard to prediction of MAS. Variability associated with Draize test outcome (e.g. in MAS values) must be considered in any future comparisons of in vivo and in vitro test results if the purpose is to predict in vivo response using in vitro data.  相似文献   
87.
A.  M.  A.  M.  A.  M.  R. Mayrhofer 《Pervasive and Mobile Computing》2008,4(3):448-479
An integrated, autonomous stick-on computing platform is proposed, consisting of (i) the Peer-it stick-on, multi-sensor, multi-actuator computer hardware, (ii) the Peer-it component-based software framework, and (iii) the Peer-it profile markup language PeerML, supporting spontaneous interaction among such platforms. The platform implements Peer-to-Peer computing principles in a self-contained, miniaturized, universal and scalable way, giving raise for application scenarios where the real-world artefacts like e.g. machines, tools or appliances–literally every thing–equipped with Peer-it technology can operate in spontaneously interacting, goal-oriented ensembles.Technically, preferences (like capabilities and goals) and context (like time, geo-position, owner, environmental conditions, etc.) of peers are kept as a profile encoded in PeerML in the local memory of Peer-its, and carried along wherever they move in space. Once peers come into spatial proximity of each other, profiles are exchanged via wireless communication, and the “similarity” of preferences is analyzed. In the case of “matching” preferences, an associated application is notified on both peers.Besides a fully functional autonomous hardware platform integrating multiple sensors, actuator arrays and wireless communication technologies, the Peer-it stick-on computer, a low-memory footprint, OSGi compliant Peer-it software framework has been implemented. We demonstrate in a flexible manufacturing systems (FMS) scenario, how the Peer-it technology can improve over centralized FMSs with respect to fault tolerance, scalability, flexibility in reconfiguration, productivity and efficiency.  相似文献   
88.
As arthroscopy of the wrist moves into the second decade, the trend for more indications for both diagnostic and therapeutic procedures will continue. It is only a matter of time before arthroscopic fusions, soft-tissue repairs, and "ectomy" procedures of all kinds become more commonplace. Whereas the advantages of the early therapeutic techniques in preserving soft-tissue structures and shortening recovery are now obvious, we will have to wait and see if the same holds true for more complicated bony and soft-tissue procedures in the next decade.  相似文献   
89.
OBJECTIVE: To characterize the biochemical mechanisms of expression of the pyruvate dehydrogenase (PDH) E1alpha subunit exon 10 R302C missense mutation. BACKGROUND: Mutations in the X-linked E1alpha subunit gene are responsible for most cases of PDH deficiency, an important cause of neurodevelopmental defects and neurodegeneration with primary lactic acidemia. Although the disease shows extreme allelic heterogeneity, the R302C mutation has been defined in several unrelated cases. METHODS: Cell lines expressing selectively either the mutant or wild-type E1alpha alleles against identical genetic backgrounds were generated from the fibroblasts of a female heterozygous for the R302C mutation. Enzyme activity, mRNA, polypeptide expression, and turnover were studied in each. RESULTS: The residual PDH activity was below measurable levels in the cell line (B5) expressing only the mutant allele and normal in the wild-type polypeptide expressing (A10) cell line, confirming that the R302C mutation alone is sufficient to cause a severe PDH deficiency. The mutant polypeptide was less stable than the wild-type polypeptide, but the steady-state level of the mutant E1alpha protein was reduced only two- to threefold. CONCLUSIONS: The primary mechanism of expression of the R302C mutation must be limitation of catalytic efficiency. We speculate that catalysis may be inhibited in the mutant polypeptide because conformational changes are induced near serine 300, a residue that is particularly important as a regulatory phosphorylation site in the wild-type polypeptide.  相似文献   
90.
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