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   1310篇
  免费   94篇
电工技术   4篇
综合类   4篇
化学工业   332篇
金属工艺   4篇
机械仪表   18篇
建筑科学   57篇
矿业工程   4篇
能源动力   17篇
轻工业   175篇
水利工程   20篇
石油天然气   2篇
武器工业   1篇
无线电   87篇
一般工业技术   182篇
冶金工业   345篇
原子能技术   1篇
自动化技术   151篇
  2023年   15篇
  2022年   56篇
  2021年   73篇
  2020年   28篇
  2019年   35篇
  2018年   37篇
  2017年   31篇
  2016年   56篇
  2015年   42篇
  2014年   55篇
  2013年   67篇
  2012年   66篇
  2011年   111篇
  2010年   92篇
  2009年   74篇
  2008年   70篇
  2007年   84篇
  2006年   48篇
  2005年   52篇
  2004年   50篇
  2003年   27篇
  2002年   26篇
  2001年   20篇
  2000年   18篇
  1999年   13篇
  1998年   12篇
  1997年   18篇
  1996年   12篇
  1995年   13篇
  1994年   13篇
  1993年   9篇
  1992年   5篇
  1991年   2篇
  1990年   7篇
  1989年   7篇
  1988年   9篇
  1987年   8篇
  1986年   6篇
  1985年   5篇
  1984年   4篇
  1983年   6篇
  1982年   2篇
  1981年   3篇
  1979年   3篇
  1975年   4篇
  1973年   2篇
  1964年   1篇
  1961年   1篇
  1960年   1篇
  1958年   1篇
排序方式: 共有1404条查询结果,搜索用时 31 毫秒
1.
2.
Literature suggests that a complex and often hostile relationship exists between the science and practice of clinical psychology. Contributors to this conflict of viewpoints are reconsidered within the proposition that there are different roads to discovery and that there may be good reasons to keep the science and practice of clinical psychology somewhat separate. Results of a national survey of 325 psychologists are reviewed that support the view that psychological practitioners value research and consider their practices to be augmented by scientific findings. However, they are in need of vehicles of communication that will help them translate scientific findings into practice. Results suggest that practitioners do more to understand scientific findings than scientists do to understand the problems that face clinical practitioners. Ways to facilitate communication between and among these groups are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
3.
Workplace studies have made a major contribution to the field of CSCW, drawing attention to subtle practices that enable effective collaboration. However, workplace studies typically focus on a single setting, making it difficult to assess the generalisability of the findings. Through a multi-site workplace study, we explore a specific collaborative process, that of the handover which occurs when a patient is transferred from one hospital or ward to another. The study demonstrates that the term ??handover?? captures a variety of collaborative practices that vary in both their form and content, reflecting aspects of the setting in which they occur. Multi-site workplace studies are shown to be essential for CSCW, not only generating findings that have relevance beyond a single setting but also focusing attention on aspects of work practice that may otherwise go unnoticed.  相似文献   
4.
Infant rats exhibit sensitive-period odor learning characterized by olfactory bulb neural changes and odor preference acquisitions critical for survival. This sensitive period is coincident with low endogenous corticosterone (CORT) levels and stress hyporesponsivity. The authors hypothesized that low corticosterone levels modulate sensitive-period learning. They assessed the effects of manipulating CORT levels by increasing and removing CORT during (Postnatal Day 8) and after (Postnatal Day 12) the sensitive period. Results show that (a) exogenous CORT prematurely ends sensitive-period odor-shock-induced preferences; (b) adrenalectomy developmentally extends the sensitive period as indicated by odor-shock-induced odor-preference learning in older pups, whereas CORT replacement can reinstate fear learning; and (c) CORT manipulation modulates olfactory bulb correlates of sensitive-period odor learning in a manner consistent with behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
5.
Erythropoietin (Epo) is a crucial hormone regulating red blood cell number and consequently the hematocrit. Epo is mainly produced in the kidney by interstitial fibroblast-like cells. Previously, we have shown that in cultures of the immortalized mouse renal fibroblast-like cell line FAIK F3-5, sphingosine 1-phosphate (S1P), by activating S1P1 and S1P3 receptors, can stabilize hypoxia-inducible factor (HIF)-2α and upregulate Epo mRNA and protein synthesis. In this study, we have addressed the role of intracellular iS1P derived from sphingosine kinases (Sphk) 1 and 2 on Epo synthesis in F3-5 cells and in mouse primary cultures of renal fibroblasts. We show that stable knockdown of Sphk2 in F3-5 cells increases HIF-2α protein and Epo mRNA and protein levels, while Sphk1 knockdown leads to a reduction of hypoxia-stimulated HIF-2α and Epo protein. A similar effect was obtained using primary cultures of renal fibroblasts isolated from wildtype mice, Sphk1−/−, or Sphk2−/− mice. Furthermore, selective Sphk2 inhibitors mimicked the effect of genetic Sphk2 depletion and also upregulated HIF-2α and Epo protein levels. The combined blockade of Sphk1 and Sphk2, using Sphk2−/− renal fibroblasts treated with the Sphk1 inhibitor PF543, resulted in reduced HIF-2α and Epo compared to the untreated Sphk2−/− cells. Exogenous sphingosine (Sph) enhanced HIF-2α and Epo, and this was abolished by the combined treatment with the selective S1P1 and S1P3 antagonists NIBR-0213 and TY52156, suggesting that Sph was taken up by cells and converted to iS1P and exported to then act in an autocrine manner through S1P1 and S1P3. The upregulation of HIF-2α and Epo synthesis by Sphk2 knockdown was confirmed in the human hepatoma cell line Hep3B, which is well-established to upregulate Epo production under hypoxia. In summary, these data show that sphingolipids have diverse effects on Epo synthesis. While accumulation of intracellular Sph reduces Epo synthesis, iS1P will be exported to act through S1P1+3 to enhance Epo synthesis. Furthermore, these data suggest that selective inhibition of Sphk2 is an attractive new option to enhance Epo synthesis and thereby to reduce anemia development in chronic kidney disease.  相似文献   
6.
Polycystic ovary syndrome (PCOS) is the most common endocrine and metabolic disorder in reproductive-aged women, and it typically involves elevated androgen levels. Recently, it has been reported that human bone marrow mesenchymal stem cells (hBM-MSCs) can regulate androgen synthesis pathways. However, the details of the mechanism are still unclear. hBM-MSC-derived secreted factors (the secretome) are promising sources of cell-based therapy as they consist of various types of proteins. It is thus important to know which proteins interact with disease-implicated biomolecules. This work aimed to investigate which secretome components contain the key factor that inhibits testosterone synthesis. In this study, we fractionated hBM-MSC-conditioned media into three fractions based on their molecular weights and found that, of the three fractions, one had the ability to inhibit the androgen-producing genes efficiently. We also analyzed the components of this fraction and established a protein profile of the hBM-MSC secretome, which was shown to inhibit androgen synthesis. Our study describes a set of protein components present in the hBM-MSC secretome that can be used therapeutically to treat PCOS by regulating androgen production for the first time.  相似文献   
7.
Similar to many other respiratory viruses, SARS-CoV-2 targets the ciliated cells of the respiratory epithelium and compromises mucociliary clearance, thereby facilitating spread to the lungs and paving the way for secondary infections. A detailed understanding of mechanism involved in ciliary loss and subsequent regeneration is crucial to assess the possible long-term consequences of COVID-19. The aim of this study was to characterize the sequence of histological and ultrastructural changes observed in the ciliated epithelium during and after SARS-CoV-2 infection in the golden Syrian hamster model. We show that acute infection induces a severe, transient loss of cilia, which is, at least in part, caused by cilia internalization. Internalized cilia colocalize with membrane invaginations, facilitating virus entry into the cell. Infection also results in a progressive decline in cells expressing the regulator of ciliogenesis FOXJ1, which persists beyond virus clearance and the termination of inflammatory changes. Ciliary loss triggers the mobilization of p73+ and CK14+ basal cells, which ceases after regeneration of the cilia. Although ciliation is restored after two weeks despite the lack of FOXJ1, an increased frequency of cilia with ultrastructural alterations indicative of secondary ciliary dyskinesia is observed. In summary, the work provides new insights into SARS-CoV-2 pathogenesis and expands our understanding of virally induced damage to defense mechanisms in the conducting airways.  相似文献   
8.
We examined whether personality judgments were present in texts of the diverse religious and philosophical traditions that emerged during the Great Transformation, an era spanning roughly 1000 BCE to 200 BCE. Some psychologists have suggested that the tendency of humans to judge personality has evolved; if some ancient societies failed to record personality judgments, it would be evidence against such an evolutionary position. In addition, learning about the prevalence and specifics of ancient personality judgments can help psychologists better understand the prehistory of personality psychology. Eight cultural traditions were studied: two each from China (Confucianism, Taoism), Greece (Classical and Hellenistic philosophy), India (Buddhism, Hinduism), and the Middle East (Judaism, Zoroastrianism). We found evidence that personality judgments were an important aspect of all of these traditions. Not only did people judge one another, but they also offered instructions on how to judge others. (PsycINFO Database Record (c) 2011 APA, all rights reserved)  相似文献   
9.
Contrary to polymer solar cells with bulk-heterojunction active layers, devices with planar-heterojunction active layers allow the decoupling of active layer phase separation from constituent crystallization, and their relative influence on device performance. We fabricated planar-heterojunction devices by first processing the electron donor and electron acceptor in isolation; they were subsequently laminated across the donor–acceptor interface to establish electrical contact. Thermal annealing was intentionally avoided after lamination to maintain the pristine charge transfer interface. Lamination thus obviates the need for solvent orthogonality; more importantly, it provides independent process tuning of individual organic semiconductor layers, ultimately allowing control over constituent structural development. We found the short-circuit current density of planar-heterojunction solar cells comprising poly(3-hexyl thiophene), P3HT, and [6,6]-phenyl-C61-butyric acid methyl ester, PCBM, as the electron donor and acceptor, respectively, to be generally independent of the annealing history of P3HT. On the contrary, thermal annealing PCBM prior to lamination mainly led to a reduction in short-circuit current density. This deterioration is correlated with the development of preferentially oriented PCBM crystals that hinders electron transport in the vertical direction.  相似文献   
10.
The highly conductive polymer PEDOT:PSS is a widely used hole transport layer and transparent electrode in organic electronic devices. To date, the mechanical and fracture properties of this conductive polymer layer are not well understood. Notably, the decohesion rate of the PEDOT:PSS layer and its sensitivity to moist environments has not been reported, which is central in determining the lifetimes of organic electronic devices. Here, it is demonstrated that the decohesion rate is highly sensitive to the ambient moisture content, temperature, and mechanical stress. The kinetic mechanisms are elucidated using atomistic bond rupture models and the decohesion process is shown to be facilitated by a chemical reaction between water molecules from the environment and strained hydrogen bonds. Hydrogen bonds are the predominant bonding mechanism between individual PEDOT:PSS grains within the layer and cause a significant loss in cohesion when they are broken. Understanding the decohesion kinetics and mechanisms in these films is essential for the mechanical integrity of devices containing PEDOT:PSS layers and yields general guidelines for the design of more reliable organic electronic devices.  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