全文获取类型
收费全文 | 3406篇 |
免费 | 69篇 |
国内免费 | 10篇 |
专业分类
电工技术 | 42篇 |
综合类 | 7篇 |
化学工业 | 385篇 |
金属工艺 | 36篇 |
机械仪表 | 74篇 |
建筑科学 | 155篇 |
矿业工程 | 15篇 |
能源动力 | 92篇 |
轻工业 | 271篇 |
水利工程 | 32篇 |
石油天然气 | 14篇 |
无线电 | 472篇 |
一般工业技术 | 468篇 |
冶金工业 | 1137篇 |
原子能技术 | 36篇 |
自动化技术 | 249篇 |
出版年
2021年 | 33篇 |
2020年 | 21篇 |
2019年 | 34篇 |
2018年 | 31篇 |
2017年 | 32篇 |
2016年 | 37篇 |
2015年 | 29篇 |
2014年 | 44篇 |
2013年 | 161篇 |
2012年 | 97篇 |
2011年 | 123篇 |
2010年 | 94篇 |
2009年 | 93篇 |
2008年 | 108篇 |
2007年 | 102篇 |
2006年 | 104篇 |
2005年 | 79篇 |
2004年 | 84篇 |
2003年 | 74篇 |
2002年 | 73篇 |
2001年 | 82篇 |
2000年 | 58篇 |
1999年 | 86篇 |
1998年 | 309篇 |
1997年 | 181篇 |
1996年 | 152篇 |
1995年 | 87篇 |
1994年 | 70篇 |
1993年 | 80篇 |
1992年 | 46篇 |
1991年 | 42篇 |
1990年 | 41篇 |
1989年 | 40篇 |
1988年 | 34篇 |
1987年 | 44篇 |
1986年 | 56篇 |
1985年 | 58篇 |
1984年 | 59篇 |
1983年 | 38篇 |
1982年 | 39篇 |
1981年 | 33篇 |
1980年 | 34篇 |
1979年 | 22篇 |
1978年 | 28篇 |
1977年 | 45篇 |
1976年 | 74篇 |
1975年 | 21篇 |
1973年 | 28篇 |
1971年 | 15篇 |
1970年 | 13篇 |
排序方式: 共有3485条查询结果,搜索用时 31 毫秒
111.
Christopher D. Sinigalliano Jared S. Ervin Laurie C. Van De Werfhorst Brian D. Badgley Elisenda Ballesté Jakob Bartkowiak Alexandria B. Boehm Muruleedhara Byappanahalli Kelly D. Goodwin Michèle Gourmelon John Griffith Patricia A. Holden Jenny Jay Blythe Layton Cheonghoon Lee Jiyoung Lee Wim G. Meijer Rachel Noble Meredith Raith Hodon Ryu Michael J. Sadowsky Alexander Schriewer Dan Wang David Wanless Richard Whitman Stefan Wuertz Jorge W. Santo Domingo 《Water research》2013
Here we report results from a multi-laboratory (n = 11) evaluation of four different PCR methods targeting the 16S rRNA gene of Catellicoccus marimammalium originally developed to detect gull fecal contamination in coastal environments. The methods included a conventional end-point PCR method, a SYBR® Green qPCR method, and two TaqMan® qPCR methods. Different techniques for data normalization and analysis were tested. Data analysis methods had a pronounced impact on assay sensitivity and specificity calculations. Across-laboratory standardization of metrics including the lower limit of quantification (LLOQ), target detected but not quantifiable (DNQ), and target not detected (ND) significantly improved results compared to results submitted by individual laboratories prior to definition standardization. The unit of measure used for data normalization also had a pronounced effect on measured assay performance. Data normalization to DNA mass improved quantitative method performance as compared to enterococcus normalization. The MST methods tested here were originally designed for gulls but were found in this study to also detect feces from other birds, particularly feces composited from pigeons. Sequencing efforts showed that some pigeon feces from California contained sequences similar to C. marimammalium found in gull feces. These data suggest that the prevalence, geographic scope, and ecology of C. marimammalium in host birds other than gulls require further investigation. This study represents an important first step in the multi-laboratory assessment of these methods and highlights the need to broaden and standardize additional evaluations, including environmentally relevant target concentrations in ambient waters from diverse geographic regions. 相似文献
112.
Innovation is invariably accepted as a central component of construction sector competitiveness. Yet, there remains a paucity of empirical research, which explores the gap between the way innovation is promoted in the policy discourse and how it is interpreted in practice. We follow the “narrative turn” in organization studies to explore the ways in which senior executives in the UK construction sector ascribe themselves with informal roles while advocating the cause of innovation. Empirical data is derived from narrative interviews with 32 senior executives who self-identify as “innovation champions”. When talking about innovation, the respondents were found to oscillate between performative narratives of innovation and more personalized stories derived from their own experience. The narratives were invariably pre-rehearsed often to the point of being monotonous. In contrast, the personalized stories tended to be engaging and emotionally laden. The tendency for senior executives to oscillate between narratives and stories is seen as an important means through which they search for meaning while at the same time legitimizing their self-identities as “innovation champions”. Of particular note is the way in which senior managers self-ascribe themselves with informal roles which are notably at odds with those described in more formalized narratives. 相似文献
113.
114.
Jessica D. Leuchter Adam T. Green Julian Gilyard Cecilia G. Rambarat Samuel S. Cho 《Israel journal of chemistry》2014,54(8-9):1152-1164
Although the main features of the protein folding problem are coming into clearer focus, the microscopic viewpoint of nucleic acid folding mechanisms is only just beginning to be addressed. Experiments, theory, and simulations are pointing to complex thermodynamic and kinetic mechanisms. As is the case for proteins, molecular dynamics (MD) simulations continue to be indispensable tools for providing a molecular basis for nucleic acid folding mechanisms. In this review, we provide an overview of biomolecular folding mechanisms focusing on nucleic acids. We outline the important interactions that are likely to be the main determinants of nucleic acid folding energy landscapes. We discuss recent MD simulation studies of empirical force field and Go-type MD simulations of RNA and DNA folding mechanisms to outline recent successes and the theoretical and computational challenges that lie ahead. 相似文献
115.
Ziv Hameiri Arman Mahboubi Soufiani Mattias K. Juhl Liangcong Jiang Fuzhi Huang Yi‐Bing Cheng Henner Kampwerth Juergen W. Weber Martin A. Green Thorsten Trupke 《Progress in Photovoltaics: Research and Applications》2015,23(12):1697-1705
Fast camera‐based luminescence‐imaging measurements on perovskite solar cells are presented. The fundamental correlation between the luminescence intensity and the open circuit voltage predicted by the generalised Planck law is confirmed, enabling various quantitative methods for the detection of efficiency‐limiting defects to be applied to this new cell structure. Interstinegly, it is found that this fundamental correlation is valid only for light‐soaked devices. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
116.
Eugenia Z. Poh Courtney Green Luca Agostinelli Marissa Penrose-Menz Ann-Kathrin Karl Alan R. Harvey Jennifer Rodger 《International journal of molecular sciences》2022,23(5)
Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique that has the potential to treat a variety of neurologic and psychiatric disorders. The extent of rTMS-induced neuroplasticity may be dependent on a subject’s brain state at the time of stimulation. Chronic low intensity rTMS (LI-rTMS) has previously been shown to induce beneficial structural and functional reorganisation within the abnormal visual circuits of ephrin-A2A5-/- mice in ambient lighting. Here, we administered chronic LI-rTMS in adult ephrin-A2A5-/- mice either in a dark environment or concurrently with voluntary locomotion. One day after the last stimulation session, optokinetic responses were assessed and fluorescent tracers were injected to map corticotectal and geniculocortical projections. We found that LI-rTMS in either treatment condition refined the geniculocortical map. Corticotectal projections were improved in locomotion+LI-rTMS subjects, but not in dark + LI-rTMS and sham groups. Visuomotor behaviour was not improved in any condition. Our results suggest that the beneficial reorganisation of abnormal visual circuits by rTMS can be significantly influenced by simultaneous, ambient visual input and is enhanced by concomitant physical exercise. Furthermore, the observed pathway-specific effects suggest that regional molecular changes and/or the relative proximity of terminals to the induced electric fields influence the outcomes of LI-rTMS on abnormal circuitry. 相似文献
117.
A Minipaster apparatus, based on a Haake Rotary Viscometer, was developed to investigate thermal pasting of aqueous starch suspensions, and to study the effects of varying heating rate, holding time and holding temperature, and of varying starch concentration. Comparison has been made with a Brabender Visco-amylograph. Attention is drawn to the marked serial dependence of the simple pasting parameters, peak viscosity temperature, peak viscosity, breakdown viscosity and setback viscosity. Relative breakdown and setback, and various ratios of pasting parameters are not markedly superior to the simple parameters as discriminants between starches. 相似文献
118.
QiLiang Chen Dae Ik Yi Josiah Nathan Joco Perez Monica Liu Steven D. Chang Meredith J. Barad Michael Lim Xiang Qian 《International journal of molecular sciences》2022,23(7)
Trigeminal neuralgia (TN) is a complex orofacial pain syndrome characterized by the paroxysmal onset of pain attacks in the trigeminal distribution. The underlying mechanism for this debilitating condition is still not clearly understood. Decades of basic and clinical evidence support the demyelination hypothesis, where demyelination along the trigeminal afferent pathway is a major driver for TN pathogenesis and pathophysiology. Such pathological demyelination can be triggered by physical compression of the trigeminal ganglion or another primary demyelinating disease, such as multiple sclerosis. Further examination of TN patients and animal models has revealed significant molecular changes, channelopathies, and electrophysiological abnormalities in the affected trigeminal nerve. Interestingly, recent electrophysiological recordings and advanced functional neuroimaging data have shed new light on the global structural changes and the altered connectivity in the central pain-related circuits in TN patients. The current article aims to review the latest findings on the pathophysiology of TN and cross-examining them with the current surgical and pharmacologic management for TN patients. Understanding the underlying biology of TN could help scientists and clinicians to identify novel targets and improve treatments for this complex, debilitating disease. 相似文献
119.
Jianhua Zhao Aihua Wang M. A. Green 《Progress in Photovoltaics: Research and Applications》1993,1(3):193-202
Emitter diffusions for conventional high-efficiency silicon solar cells have commonly been designed to be very shallow to improve the short-wavelength response of the cells. This first part of a two-part paper has a substantial tutorial content and analyses the effect of the emitter design on cell performance with different cell surface passivation conditions. the analysis shows that shallow emitters are only necessary for cells with poor surface passivation. In contrast, high-efficiency cells with good surface passivation do not necessarily need shallow emitters. the application of these design insights into recent generations of high-efficiency passivated emitter solar cells is also discussed. 相似文献
120.
M. L. H. Green 《Polymer International》1996,41(1):98-98