全文获取类型
收费全文 | 3601篇 |
免费 | 126篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 51篇 |
综合类 | 1篇 |
化学工业 | 692篇 |
金属工艺 | 221篇 |
机械仪表 | 55篇 |
建筑科学 | 162篇 |
矿业工程 | 5篇 |
能源动力 | 105篇 |
轻工业 | 303篇 |
水利工程 | 40篇 |
石油天然气 | 40篇 |
无线电 | 291篇 |
一般工业技术 | 509篇 |
冶金工业 | 773篇 |
原子能技术 | 30篇 |
自动化技术 | 458篇 |
出版年
2023年 | 21篇 |
2022年 | 38篇 |
2021年 | 64篇 |
2020年 | 51篇 |
2019年 | 59篇 |
2018年 | 63篇 |
2017年 | 58篇 |
2016年 | 84篇 |
2015年 | 73篇 |
2014年 | 72篇 |
2013年 | 208篇 |
2012年 | 141篇 |
2011年 | 165篇 |
2010年 | 116篇 |
2009年 | 133篇 |
2008年 | 161篇 |
2007年 | 145篇 |
2006年 | 106篇 |
2005年 | 119篇 |
2004年 | 119篇 |
2003年 | 103篇 |
2002年 | 77篇 |
2001年 | 61篇 |
2000年 | 60篇 |
1999年 | 70篇 |
1998年 | 118篇 |
1997年 | 80篇 |
1996年 | 76篇 |
1995年 | 71篇 |
1994年 | 62篇 |
1993年 | 71篇 |
1992年 | 60篇 |
1991年 | 44篇 |
1990年 | 57篇 |
1989年 | 47篇 |
1988年 | 50篇 |
1987年 | 52篇 |
1986年 | 42篇 |
1985年 | 45篇 |
1984年 | 52篇 |
1983年 | 47篇 |
1982年 | 41篇 |
1981年 | 34篇 |
1980年 | 45篇 |
1979年 | 45篇 |
1978年 | 32篇 |
1977年 | 25篇 |
1976年 | 34篇 |
1975年 | 28篇 |
1974年 | 21篇 |
排序方式: 共有3736条查询结果,搜索用时 11 毫秒
1.
Dr. Li Di Prof. Per Artursson Dr. Alex Avdeef Prof. Leslie Z. Benet Prof. J. Brian Houston Dr. Manfred Kansy Edward H. Kerns Prof. Hans Lennernäs Dr. Dennis A. Smith Prof. Kiyohiko Sugano 《ChemMedChem》2020,15(20):1862-1874
Passive permeability is a key property in drug disposition and delivery. It is critical for gastrointestinal absorption, brain penetration, renal reabsorption, defining clearance mechanisms and drug-drug interactions. Passive diffusion rate is translatable across tissues and animal species, while the extent of absorption is dependent on drug properties, as well as in vivo physiology/pathophysiology. Design principles have been developed to guide medicinal chemistry to enhance absorption, which combine the balance of aqueous solubility, permeability and the sometimes unfavorable compound characteristic demanded by the target. Permeability assays have been implemented that enable rapid development of structure-permeability relationships for absorption improvement. Future advances in assay development to reduce nonspecific binding and improve mass balance will enable more accurately measurement of passive permeability. Design principles that integrate potency, selectivity, passive permeability and other ADMET properties facilitate rapid advancement of successful drug candidates to patients. 相似文献
2.
Using an integrated process of data and modeling in HRA 总被引:1,自引:0,他引:1
John Wreathall Dennis Bley Emilie Roth Jordan Multer Thomas Raslear 《Reliability Engineering & System Safety》2004,83(2):221
The paper describes an approach taken to estimate the probabilities of failure associated with various railroad tasks to prevent accidents (principally collisions and derailments). These probabilities were estimated using an expert elicitation process that used partially relevant data available from a variety of databases and that were filtered and scaled to make them more directly relevant to the analyses being performed. Extensive qualitative studies were performed prior to the elicitation process to identify relevant contexts under which the tasks can be performed. 相似文献
3.
4.
Lasers containing a nanopatterned active layer demonstrating excellent threshold characteristics are presented. The nanopatterned active layer is fabricated using high-resolution electron beam lithography and selective-area metal organic chemical vapour deposition crystal growth. Results demonstrating an order of magnitude improvement over previous results are reported. 相似文献
5.
Amanda Alliband Daniel W. Lenz Laura E. Stevenson Travis Whitmer Rex Cash Dennis Burns Sarah Hall William T.K. Stevenson 《Progress in Organic Coatings》2008
A model has been proposed to explain the failure of the original BMS10-39 epoxy paint on upper vertical surfaces in B-52 fuel tanks. The model involves interaction of the paint with DIEGME, a fuel system ice inhibitor (FSII) in jet fuel, that is distilled from the liquid fuel. In this communication, distillation experiments used to support the model are refined to better match the mass transfer of vapor from fuel in a B-52 fuel tank at close to room temperature. The interaction of these lower temperature distillates with the paint affirms the earlier model. On the basis of these experiments it is proposed that paint failure may be controlled or eliminated by reducing the level of DIEGME in the fuel. Proposed changes in military jet fuel composition are detailed. 相似文献
6.
Halo effects in rating specific pieces of work, as in educational grading, have received little attention. Grades awarded by 2 independent graders to undergraduate projects were analyzed with a correlated uniqueness model. Grades showed substantial halo despite being awarded by expert assessors at the time of reading the work. There was greater halo between different grades applying to the same section of the project than between grades applying to different sections. Supervisors who had regular contact with the student whose work they were grading showed no more halo than other graders. More reliable graders showed less within-section halo than graders of lower reliability but equal between-sections halo. The halo effects observed cannot be entirely attributable to a unitary general impression. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
In its policy rationale for evidence-based practice in psychology (EBPP), the APA Presidential Task Force on Evidence-Based Practice (see record 2006-05893-001) claims to have constituted itself with "scientists and practitioners from a wide range of perspectives and traditions, reflecting the diverse perspectives within the field" (p. 273). We applaud this attention to diversity but contend that an entire perspective of the debate was omitted in the Task Force's newly approved policy and its underlying report. The failure to consider a philosophy of science perspective led the Task Force to make a number of epistemological assumptions that are not based on evidence or rationale and that thus violate the very spirit of evidence-based decision making. In this comment, we reveal a few of these assumptions and discuss their detrimental consequences. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
8.
This paper presents a semianalytical method for the prediction of interlaminar stresses and displacements near the free edges and ply cracks in general angle-ply laminates subjected to biaxial extensions and/or in plane shear deformation. The method is based on a state space representation of the three-dimensional equations of elasticity. Numerical solutions are obtained by using layer refinement in the through thickness direction and Fourier series expansion in the other directions. By this approach, an angle-ply laminate may be composed of an arbitrary number of monoclinic layers and each layer may have different material property and thickness. This method guarantees continuous fields of all interlaminar stresses across interfaces between material layers. Numerical results are compared with those obtained from other methods. It is found that the theory provides a satisfactory approximation to the stress singularities near the free edges and ply cracks. Numerical solutions for antisymmetric laminates under extension and general laminates under shearing are new in the literature and can be used as benchmarks for validating new models. 相似文献
9.
Hitsman Brian; Borrelli Belinda; McChargue Dennis E.; Spring Bonnie; Niaura Raymond 《Canadian Metallurgical Quarterly》2003,71(4):657
The authors conducted a meta-analysis of published studies to (a) evaluate the premise that a history of major depression is associated with failure to quit smoking and (b) identify factors that moderate the relationship between history of depression and cessation outcome. Fifteen studies met the selection requirements and were coded for various study methodology and treatment characteristics. DSTAT was used to calculate individual study effect sizes, determine the mean effect size across studies. and test for moderator effects. No differences in either short-term (≤ 3 months) or long-term abstinence rates (≥ 6 months) were observed between smokers positive versus negative for history of depression. Lifetime history of major depression does not appear to be an independent risk factor for cessation failure in smoking cessation treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
OBJECTIVE: The aim of this study was to evaluate both the importance of the screening strategy and the familial aggregation characteristics of families with hypercholesterolemic children. PATIENTS AND METHODS: Ninety-one families (369 subjects) with one hypercholesterolemic child were studied. In addition to clinical and general biochemical evaluation, lipids including apo A-I and B-100 were examined. LDL was quantified under ultracentrifugation. RESULTS: Among the 91 children studied, 10 (10.99%) suffered heterozygous hypercholesterolemia, while 81 (89.01%) suffered polygenic hypercholesterolemia. Following a diet, polygenic children exhibited normal lipid parameters. In heterozygous children a decrease of 19% for total cholesterol, 19.9% for LDL-cholesterol and 16.3% for apo B were observed. When starting the study, 77.5% of the family members thought that they had normal serum lipid values. At the end of the study it was confirmed that only 28% were really normolipemic, indicating that 49.4% of the individual did not know that they were suffering dyslipemia. The study also showed that fathers exhibited the highest incidence of hypercholesterolemia (80.2%) followed by brothers (65.6%) and mothers (61.5%). Therefore, 69.4% of the individuals studied exhibited dyslipemia. CONCLUSIONS: The screening strategy allows one to diagnose a high percentage (almost 50%) of individuals suffering hypercholesterolemia in families with a child previously diagnosed of this pathology. Moreover, in these families there is a high degree of familiar aggregation of dyslipemia. 相似文献