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   939篇
  免费   54篇
  国内免费   1篇
电工技术   20篇
化学工业   307篇
金属工艺   9篇
机械仪表   8篇
建筑科学   39篇
矿业工程   1篇
能源动力   19篇
轻工业   170篇
水利工程   15篇
石油天然气   8篇
无线电   50篇
一般工业技术   109篇
冶金工业   153篇
原子能技术   9篇
自动化技术   77篇
  2023年   14篇
  2022年   36篇
  2021年   52篇
  2020年   21篇
  2019年   21篇
  2018年   36篇
  2017年   27篇
  2016年   28篇
  2015年   26篇
  2014年   26篇
  2013年   48篇
  2012年   47篇
  2011年   68篇
  2010年   43篇
  2009年   42篇
  2008年   45篇
  2007年   38篇
  2006年   40篇
  2005年   24篇
  2004年   26篇
  2003年   32篇
  2002年   16篇
  2001年   10篇
  2000年   7篇
  1999年   15篇
  1998年   21篇
  1997年   17篇
  1996年   11篇
  1995年   15篇
  1994年   17篇
  1993年   7篇
  1992年   10篇
  1991年   3篇
  1990年   4篇
  1989年   11篇
  1988年   3篇
  1986年   4篇
  1985年   9篇
  1983年   3篇
  1982年   5篇
  1981年   7篇
  1980年   10篇
  1979年   4篇
  1976年   5篇
  1975年   5篇
  1973年   5篇
  1969年   2篇
  1959年   2篇
  1947年   2篇
  1946年   2篇
排序方式: 共有994条查询结果,搜索用时 15 毫秒
91.
Particulate matter (PM) 2.5 pollution is a prevalent environmental and public health issue that has raised serious global concerns. Because standard heating, ventilation, and air conditioning filters are incapable of filtering out PM 2.5 particles efficiently, different methods of PM 2.5 filtration, such as physical filtration and electrostatic filtration, are under investigation to develop a filter with a high filtration efficiency and a low pressure drop. According to various studies, pressure drop has a significant influence on the filtration efficiency. An equation for the theoretical trend was generated based on the composite data gathered from similar filtration studies and was used to evaluate the relationship between pressure drop and filtration efficiency. Here, the theoretical equation indicated that the filtration efficiency increased as the pressure drop on a filter increased until 0.01 psi where the efficiency remained near constant at approximately 99.9%. In this study, we introduce a graphite oxide (GO) and polyaniline (PANi) composite hybrid filter in order to create a low-pressure (1.2 psi) drop filter. By adding GO flakes to the PANi matrix, we not only produced a highly permeable filter while allowing continuous gas flow, but also achieved a remarkable and highly effective PM 2.5 filter with a filtration efficiency of 99.7 ± 0.08%.  相似文献   
92.
X-chromosomal retinitis pigmentosa (RP) frequently is caused by mutations in the retinitis pigmentosa GTPase regulator (RPGR) gene. We evaluated the potential of PTC124 (Ataluren, TranslamaTM) treatment to promote ribosomal read-through of premature termination codons (PTC) in RPGR. Expression constructs in HEK293T cells showed that the efficacy of read-through reagents is higher for UGA than UAA PTCs. We identified the novel hemizygous nonsense mutation c.1154T > A, p.Leu385* (NM_000328.3) causing a UAA PTC in RPGR and generated patient-derived fibroblasts. Immunocytochemistry of serum-starved control fibroblasts showed the RPGR protein in a dot-like expression pattern along the primary cilium. In contrast, RPGR was no longer detectable at the primary cilium in patient-derived cells. Applying PTC124 restored RPGR at the cilium in approximately 8% of patient-derived cells. RT-PCR and Western blot assays verified the pathogenic mechanisms underlying the nonsense variant. Immunofluorescence stainings confirmed the successful PTC124 treatment. Our results showed for the first time that PTC124 induces read-through of PTCs in RPGR and restores the localization of the RPGR protein at the primary cilium in patient-derived cells. These results may provide a promising new treatment option for patients suffering from nonsense mutations in RPGR or other genetic diseases.  相似文献   
93.
In cancer therapy, the application of (fractionated) harsh radiation treatment is state of the art for many types of tumors. However, ionizing radiation is a “double-edged sword”—it can kill the tumor but can also promote the selection of radioresistant tumor cell clones or even initiate carcinogenesis in the normal irradiated tissue. Individualized radiotherapy would reduce these risks and boost the treatment, but its development requires a deep understanding of DNA damage and repair processes and the corresponding control mechanisms. DNA double strand breaks (DSBs) and their repair play a critical role in the cellular response to radiation. In previous years, it has become apparent that, beyond genetic and epigenetic determinants, the structural aspects of damaged chromatin (i.e., not only of DSBs themselves but also of the whole damage-surrounding chromatin domains) form another layer of complex DSB regulation. In the present article, we summarize the application of super-resolution single molecule localization microscopy (SMLM) for investigations of these structural aspects with emphasis on the relationship between the nano-architecture of radiation-induced repair foci (IRIFs), represented here by γH2AX foci, and their chromatin environment. Using irradiated HeLa cell cultures as an example, we show repair-dependent rearrangements of damaged chromatin and analyze the architecture of γH2AX repair clusters according to topological similarities. Although HeLa cells are known to have highly aberrant genomes, the topological similarity of γH2AX was high, indicating a functional, presumptively genome type-independent relevance of structural aspects in DSB repair. Remarkably, nano-scaled chromatin rearrangements during repair depended both on the chromatin domain type and the treatment. Based on these results, we demonstrate how the nano-architecture and topology of IRIFs and chromatin can be determined, point to the methodological relevance of SMLM, and discuss the consequences of the observed phenomena for the DSB repair network regulation or, for instance, radiation treatment outcomes.  相似文献   
94.
Platinum catalyst supported on a medium surface area -SiC was successfully used for the catalytic combustion of model carbon particles and compared to a catalyst supported on a low surface area -SiC. The -SiC-based catalyst showed no deactivation as a function of cycling tests while a strong deactivation was observed on the -SiC-based catalyst. This deactivation was attributed to the progressive encapsulation of the platinum particles by a layer of silica which built up during the combustion cycle. These results render possible the use of Pt/-SiC catalyst as a diesel carbon particle catalytic filter with continuous regeneration.  相似文献   
95.
96.
Within the medical domain there are clear expectations as to how a patient should respond to treatments administered. When these responses are not observed it can be challenging for clinicians to understand the anomalous responses. The work reported here describes a tool which can detect anomalous patient responses to treatment and further suggest hypotheses to explain the anomaly. In order to develop this tool, we have undertaken a study to determine how Intensive Care Unit (ICU) clinicians identify anomalous patient responses; we then asked further clinicians to provide potential explanations for such anomalies. The high level reasoning deployed by the clinicians has been captured and generalised to form the procedural component of the ontology-driven tool. An evaluation has shown that the tool successfully reproduced the clinician’s hypotheses in the majority of cases. Finally, the paper concludes by describing planned extensions to this work.  相似文献   
97.
Objective: The aim of this study was to assess an aspect of metamemory never examined before in patients with temporal lobe epilepsy (TLE): the ability to upgrade the accuracy of one's memory predictions after study. Method: Four lists of different levels of difficulty and relatedness were presented to 15 TLE patients and 15 control participants, who were asked to predict their subsequent recall both before and after studying each list. Results: The results showed clear impairment in recall in TLE patients. However, both TLE patients and controls showed an improvement in accuracy in their poststudy predictions compared with their prestudy predictions, showing that both groups were able to upgrade their metamemory predictions. Unexpectedly, prediction accuracy was overall higher in TLE patients than in controls. Moreover, study time was allocated in both groups taking into account the characteristics of the list. Conclusion: These results confirm and extend findings of Howard et al. (2010) of intact metamemory in TLE patients, and provide further support to the dissociation between memory and metamemory in this clinical population. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
98.
Glass transition of thermo‐molded biomaterials made from wheat gluten and its main protein classes is studied by dynamic mechanical analysis (DMA). The materials are plasticized with variable contents of glycerol (30–40 wt %) and water (0–20 wt %). For all materials, three successive relaxation phases are systematically detected. Their positions shift to lower temperature as the plasticizer content of materials increases. Composition in gluten, glycerol and water of each relaxation phase is estimated using the Couchman‐Karasz model. Irrespective of the plasticizer content or composition, the relaxation phases shows rather constant plasticizer volume fractions. The low‐, middle‐, and high relaxation phases include respectively around 30, 60 and 80 vol % of gluten protein. These relaxations are assigned to the segmental motion of the surface amino‐acid side groups, to the collective motion of packed gluten proteins, and to the gain in protein conformational mobility as a 2D network of interacting plasticizer molecules forms. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43254.  相似文献   
99.
Compared initial and 3-yr follow-up peer ratings of 19 boys, who were in Grades 1–3 at the beginning of the study, who had attention deficit disorder with hyperactivity (ADDH). When the entire group was considered, nominations on the Aggression and Likability factors of a pupil evaluation inventory improved. Subgroups were created using teacher ratings on an aggression scale. Peer ratings of Aggression improved for Ss whom teachers rated below the median on the aggression scale but not for Ss rated above the median. Subgroups reflecting other teacher and peer ratings were less effective in predicting differential change in peer ratings of ADDH Ss. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
100.
The impact on Canadian professional psychological treatment practices of the American Psychological Association""s Division 12 (Clinical Psychology) Task Force""s development of criteria and listings for empirically supported psychological treatments, along with other industrial efforts to standardize the identification of treatments with established efficacy is described in the article by J. Hunsley et al (see record 1999-01869-001). Here Hunsley et al extend their previous discussion and reply to other commentaries (see records 1999-01869-002, 1999-01869-003, 1999-01869-004, 1999-01869-005, 1999-01869-006) by viewing the current emphases in the Canadian health care system on accountability and empirically supported treatment (ESTs) as an unparalleled opportunity for professional psychology to deliver on its birthright. The generalizability of US experiences to Canadian contexts is discussed. Clinical practice guidelines should and will become the norm for providing evidence-based services in psychology, yet it would be impossible to develop such a guideline without empirical evidence proving that there are "best" interventions for a given problem. Canadian research issues in this light are discussed along with future challenges to professional psychology in Canada. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  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