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   797篇
  免费   33篇
  国内免费   1篇
工业技术   831篇
  2023年   5篇
  2022年   7篇
  2021年   28篇
  2020年   10篇
  2019年   16篇
  2018年   14篇
  2017年   17篇
  2016年   32篇
  2015年   24篇
  2014年   27篇
  2013年   39篇
  2012年   36篇
  2011年   50篇
  2010年   30篇
  2009年   33篇
  2008年   42篇
  2007年   52篇
  2006年   39篇
  2005年   14篇
  2004年   16篇
  2003年   17篇
  2002年   16篇
  2001年   9篇
  2000年   10篇
  1999年   24篇
  1998年   10篇
  1997年   16篇
  1996年   9篇
  1995年   12篇
  1994年   14篇
  1993年   8篇
  1992年   13篇
  1991年   12篇
  1990年   11篇
  1989年   12篇
  1988年   10篇
  1987年   9篇
  1986年   9篇
  1985年   6篇
  1984年   4篇
  1983年   6篇
  1982年   6篇
  1981年   5篇
  1980年   4篇
  1979年   6篇
  1978年   11篇
  1977年   7篇
  1975年   3篇
  1973年   4篇
  1901年   2篇
排序方式: 共有831条查询结果,搜索用时 62 毫秒
91.
92.
Zusammenfassung  Bie Bundesregierung will die Vorratsdatenspeicherung nach der EG-Richtlinie 2006/24/EG vom 15. M?rz 2006 durch einen neu geschaffenen § 113 a TKG umsetzen. Die Regelung ist erheblichen verfassungsrechtlichen Bedenken ausgesetzt, weil sie zu einer anlasslosen Massenspeicherung von Verkehrsdaten zu unbestimmten Zwecken führt. Sie führt zu einem Paradigmenwechsel im Verh?ltnis zwischen Bürger und Staat. Nicht die Einschr?nkung der Freiheit wird begründungspflichtig, sondern im Gegenteil die Ausübung der bürgerlichen Grundfreiheiten der elektronischen Kommunikation. Dr. Johann Bizer Stellvertretender Landesbeauftragter für den Datenschutz Schleswig-Holstein, Unabh?ngiges Landeszentrum für Datenschutz (ULD).  相似文献   
93.
Transplantation represents a breaching of the bodily integrity of the patient, and can lead to anxiety, depression and an identity problem. In the post-transplantation phase also, the patient undergoes further stress associated with check examinations and treatment. Standardized surveys show that the fear of graft rejection remains with the patient for the rest of his/her life. The new situation also has an influence on partnership, family and the overall psychosocial setting. All this adds up to a need for psychosomatic care, support and, where indicated, appropriate treatment in every transplantation patient. The broad spectrum of possible measures available in this connection is discussed.  相似文献   
94.
95.
The aim of this study was to elucidate whether and to what extent fresh produce from Germany plays a role as a carrier and reservoir of antibiotic resistant bacteria. For this purpose, 1001 vegetables (fruit, root, bulbous vegetables, salads and cereals) were collected from 13 farms and 11 supermarkets in Germany and examined bacteriologically. Phenotypic resistance of Enterobacter cloacae (n = 172); Enterobacter gergoviae (n = 92); Pantoea agglomerans (n = 96); Pseudomonas aeruginosa (n = 295); Pseudomonas putida (n = 106) and Enterococcus faecalis (n = 100) against up to 30 antibiotics was determined by using the microdilution method. Resistance to ß-lactams was most frequently expressed by P. agglomerans and E. gergoviae against cefaclor (41% and 29%). Relatively high resistance rates were also observed for doxycycline (23%), erythromycin (21%) and rifampicin (65%) in E. faecalis, for spectinomycin (28%) and mezlocillin (12%) in E. cloacae, as well as for streptomycin (19%) in P. putida. In P. aeruginosa, relatively low resistance rates were observed for the aminoglycosides amikacin, apramicin, gentamicin, neomycin, netilmicin and tobramycin (< 4%); 11% was resistant to streptomycin. No glycopeptide-resistant enterococci were observed. Resistance rates of bacteria isolated from farm samples were higher than those of the retail markets whenever significant differences were observed. This suggests that expressing resistance is at the expense of bacterial viability, since vegetables purchased directly at the farm are probably fresher than at the supermarket, and they have not been exposed to stress factors. However, this should not keep the customer from buying directly at the farm, since the overall resistance rates were not higher than observed in bacteria from human or animal origin. Instead, peeling or washing vegetables before eating them raw is highly recommended, since it reduces not only the risk of contact with pathogens, but also that of ingesting and spreading antibiotic resistant bacteria.  相似文献   
96.
Improving analytical precision is a major goal in quantitative differential proteomics as high precision ensures low numbers of outliers, a source of false positives with regard to quantification. In addition, higher precision increases statistical power, i.e., the probability to detect significant differences. With chemical labeling using isobaric tags for relative and absolute quantitation (iTRAQ) or tandem mass tag (TMT) reagents, quantification is based on the extraction of reporter ions from tandem mass spectrometry (MS/MS) spectra. We compared the performance of two versions of the LTQ Orbitrap higher energy collisional dissociation (HCD) cell with and without an axial electric field with regard to reporter ion quantification. The HCD cell with the axial electric field was designed to push fragment ions into the C-trap and this version is mounted in current Orbitrap XL ETD and Orbitrap Velos instruments. Our goal was to evaluate whether the purported improvement in ion transmission had a measurable impact on the precision of MS/MS based quantification using peptide labeling with isobaric tags. We show that the axial electric field led to an increased percentage of HCD spectra in which the complete set of reporter ions was detected and, even more important, to a reduction in overall variance, i.e., improved analytical precision of the acquired data. Notably, adequate precision of HCD-based quantification was maintained even for low precursor ion intensities of a complex biological sample. These findings may help researchers in their design of quantitative proteomics studies using isobaric tags and establish HCD-based quantification on the LTQ Orbitrap as a highly precise approach in quantitative proteomics.  相似文献   
97.
In order to account for complex interactions between humans climate and the water cycle, the research consortium GLOWA-Danube (www.glowa-danube.de) has developed the simulation system DANUBIA which consists of 17 coupled models. DANUBIA was applied to investigate various impacts of global-change between 2011 and 2060 in the Upper Danube Catchment. This article describes part 2 of an article series with investigations of socio-economic aspects, while part 1 (Barthel et al. in Grundwasser 16(4), doi:10.1007/s007-011-01794, 2011) deals with natural-spatial aspects. The principles of socio-economic actor-modeling and interactions between socio-economic and natural science model components are described here. We present selected simulations that show impacts on groundwater from changes in agriculture, tourism, economy, domestic water users and water supply. Despite decreases in water consumption, the scenario simulations show significant decreases in groundwater quantity. On the other hand, groundwater quality will likely be influenced more severely by land use changes compared to direct climatic causes. However, overall changes will not be dramatic.  相似文献   
98.
99.
100.
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