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   705篇
  免费   32篇
  国内免费   2篇
电工技术   3篇
综合类   1篇
化学工业   188篇
金属工艺   30篇
机械仪表   41篇
建筑科学   58篇
矿业工程   2篇
能源动力   9篇
轻工业   74篇
水利工程   7篇
石油天然气   1篇
无线电   28篇
一般工业技术   158篇
冶金工业   46篇
原子能技术   5篇
自动化技术   88篇
  2023年   10篇
  2022年   17篇
  2021年   12篇
  2020年   7篇
  2019年   18篇
  2018年   14篇
  2017年   14篇
  2016年   16篇
  2015年   20篇
  2014年   22篇
  2013年   36篇
  2012年   32篇
  2011年   52篇
  2010年   44篇
  2009年   44篇
  2008年   35篇
  2007年   37篇
  2006年   35篇
  2005年   30篇
  2004年   28篇
  2003年   16篇
  2002年   27篇
  2001年   8篇
  2000年   12篇
  1999年   12篇
  1998年   17篇
  1997年   14篇
  1996年   8篇
  1995年   5篇
  1994年   3篇
  1993年   10篇
  1992年   7篇
  1990年   8篇
  1989年   6篇
  1988年   8篇
  1986年   6篇
  1985年   6篇
  1984年   4篇
  1982年   3篇
  1981年   4篇
  1980年   2篇
  1979年   2篇
  1978年   5篇
  1977年   6篇
  1976年   3篇
  1972年   4篇
  1971年   2篇
  1966年   1篇
  1960年   1篇
  1956年   1篇
排序方式: 共有739条查询结果,搜索用时 15 毫秒
81.
The protein encoded by the pancreatic colipase (CLPS) gene is an essential cofactor needed by pancreatic triglyceride lipase (PNLIP) for efficient dietary lipid hydrolysis. Since the inhibition of lipase activity was shown to reduce the incidence of type 2 diabetes mellitus, we tested the hypothesis that genetic variations in the CLPS and PNLIP genes are associated with type 2 diabetes; 47 unrelated subjects were screened for polymorphisms of the CLPS and PNLIP genes. A nested-case control study of 192 incident type 2 diabetes subjects and 384 sex- and age-matched controls taken from the European Prospective Investigation into Cancer and Nutrition Potsdam Cohort (EPIC) was employed for association studies. The Metabolic Intervention Cohort Kiel (MICK) consisting of 716 males was used for verification. A novel putative functional polymorphism (Arg109Cys) was identified in the CLPS gene. The frequencies of the Arg/Cys genotype were 2.6% in EPIC and 2.2% in MICK study subjects. No homozygotes for the Cys/Cys genotype were found in either study population. Logistic regression analysis showed a statistically significant association of the Arg/Cys genotype with an increased risk of type 2 diabetes. The odds ratios estimated by the model were 3.75 (95%CI = 1.13-12.49, p = 0.03) in EPIC and 4.86 (95%CI = 1.13-20.95, p = 0.03) in MICK. No comparable associations were found with other traits of the insulin-resistance syndrome (e. g.; body mass index, waist to hip ratio). In conclusion, we obtained evidence in two German Caucasian study populations that the variant of the rare CLPS Arg109Cys polymorphism might contribute to increased susceptibility of type 2 diabetes.  相似文献   
82.
The paper reports a study of a videoconference-based environment in decentralized university education and factors contributing to the success of teaching and learning in the environment. The focus of the paper is on the role of a person having the formal responsibilities of a technician. An ethnographic study conducted over the course of a year revealed that the contribution of this person far exceeded the scope of formal responsibilities. The person, who was acting in the setting as a facilitator, was found to possess expertise, which was critically important for supporting interaction between remote participants at several levels, such as attention management, time management, acquisition of setting-specific skills, and coordination within a larger institutional context. The findings suggest that supra-situational activities can be important factors for the successful functioning and development of emerging learning environments.This revised version was published online in March 2005 with corrections to the cover date  相似文献   
83.
By throwing TAT pictures on a screen in varying degrees of light intensity, precognitive defence organization was used to screen 412 aviation cadets. Ss drew pictures of what they saw. Protocols were rated. Validity varied by rater. The DMT is likely to increase the validity of the total test battery. (16 ref.) (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
84.
Enrichment procedures for trace metal analysis by atomic absorption spectrophotometry have been investigated. The detection limits are primarily determined by the enrichment factor and the accuracies have been found to be roughly the same within the same absorption ranges independent of the method used. One of 28 papers presented at the Symposium, “Metal-Catalyzed Lipid Oxidation,” ISF-AOCS World Congress, Chicago, September 1970.  相似文献   
85.
86.
Light up galectin: Photoprobes based on thiodigalactoside were prepared for galectin‐3, a lectin linked to cancer. The probes contained either benzophenone or acetophenone moieties as the photolabel for covalent attachment to the protein. One particular probe labeled galectin‐3 selectively, even in the presence of cell lysate.

  相似文献   

87.
88.
Mathematical modelling has proven to be very useful in process design, operation and optimisation. A recent trend in WWTP modelling is to include the different subunits in so-called plant-wide models rather than focusing on parts of the entire process. One example of a typical plant-wide model is the coupling of an upstream activated sludge plant (including primary settler, and secondary clarifier) to an anaerobic digester for sludge digestion. One of the key challenges when coupling these processes has been the definition of an interface between the well accepted activated sludge model (ASM1) and anaerobic digestion model (ADM1). Current characterisation and interface models have key limitations, the most critical of which is the over-use of Xc (or lumped complex) variable as a main input to the ADM1. Over-use of Xc does not allow for variation of degradability, carbon oxidation state or nitrogen content. In addition, achieving a target influent pH through the proper definition of the ionic system can be difficult. In this paper, we define an interface and characterisation model that maps degradable components directly to carbohydrates, proteins and lipids (and their soluble analogues), as well as organic acids, rather than using Xc. While this interface has been designed for use with the Benchmark Simulation Model No. 2 (BSM2), it is widely applicable to ADM1 input characterisation in general. We have demonstrated the model both hypothetically (BSM2), and practically on a full-scale anaerobic digester treating sewage sludge.  相似文献   
89.
90.
The distribution of different iron (Fe) species in soils, sediments, and surface waters has a large influence on the mobility and availability of Fe, other nutrients, and potentially toxic trace elements. However, the knowledge about the specific forms of Fe that occurs in these systems is limited, especially regarding associations of Fe with natural organic matter (NOM). In this study, extended X-ray absorption fine structure (EXAFS) spectroscopy was used to characterize Fe(III) in organic soils (pH 4.6-6.0) with varying natural Fe content. The EXAFS data were subjected to wavelet transform analysis, to facilitate the identification of the nature of backscattering atoms, and to conventional EXAFS data fitting. The collective results showed the existence of two pools of iron: mononuclear Fe(III)-NOM complexes and precipitated Fe(III) (hydr)oxides. In the soil with lowest pH (4.6) and Fe content mononuclear organic complexes were the completely dominating fraction whereas in soils with higher pH and Fe content increasing amounts of Fe (hydr)oxides were detected. These results are of environmental importance, as the different iron pools most likely have markedly different reactivities.  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