全文获取类型
收费全文 | 486篇 |
免费 | 1篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 173篇 |
金属工艺 | 58篇 |
机械仪表 | 2篇 |
建筑科学 | 1篇 |
矿业工程 | 8篇 |
能源动力 | 1篇 |
轻工业 | 15篇 |
水利工程 | 1篇 |
石油天然气 | 3篇 |
无线电 | 20篇 |
一般工业技术 | 57篇 |
冶金工业 | 113篇 |
原子能技术 | 4篇 |
自动化技术 | 27篇 |
出版年
2013年 | 16篇 |
2011年 | 6篇 |
2010年 | 4篇 |
2009年 | 7篇 |
2008年 | 8篇 |
2007年 | 5篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2003年 | 6篇 |
2002年 | 16篇 |
2001年 | 4篇 |
2000年 | 10篇 |
1999年 | 4篇 |
1998年 | 28篇 |
1997年 | 20篇 |
1996年 | 21篇 |
1995年 | 9篇 |
1994年 | 7篇 |
1993年 | 12篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 9篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1982年 | 7篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1978年 | 9篇 |
1977年 | 15篇 |
1976年 | 24篇 |
1975年 | 14篇 |
1974年 | 17篇 |
1973年 | 21篇 |
1972年 | 15篇 |
1971年 | 14篇 |
1970年 | 7篇 |
1969年 | 7篇 |
1968年 | 6篇 |
1967年 | 6篇 |
1966年 | 5篇 |
1965年 | 3篇 |
1964年 | 3篇 |
1963年 | 3篇 |
1926年 | 3篇 |
1921年 | 5篇 |
排序方式: 共有487条查询结果,搜索用时 15 毫秒
1.
In January 1990, a well-established heart transplant program added a psychosocial evaluation procedure to its medical evaluation of potential transplant recipients. To determine the predictive value of psychosocial evaluation for decisions to list patients for a transplant and for ultimate clinical outcomes, we reviewed records of 191 patients who underwent psychosocial evaluation in the subsequent 3 years. Informal prescreening for obvious psychopathology and other disqualifiers almost certainly restricted the ranges of psychosocial factors observed in the sample. Of 120 patients listed, 61 actually received transplants. Psychosocial factors were little used in deciding whether to list the patients and were not predictive of recipients' medical outcome or compliance, but were moderately predictive of complication rates and difficulty of managing patients after transplantation. Although psychosocial evaluation of prescreened potential transplant recipients has little value in predicting medical outcome, it may be useful for planning and scheduling care after transplantation. 相似文献
2.
Investigated the ways in which patient and therapist gender influence the nature of patients' internalized representations of their therapist and the therapeutic relationship. A sample of 66 patients (29 males) completed the Therapist Representation Inventory (J. D. Geller et al, 1982), a self-report instrument designed to assess discrete properties of evoked representations. Results indicated widespread similarities between male and female patients in terms of the forms with which representations are evoked and the themes embodied in these representations. The differences that emerged suggest that women are more likely to keep their therapists in mind (and for longer periods of time) when working on their problems outside of therapy and that women with male therapists are especially likely to daydream about therapy and acknowledge missing their therapist in between sessions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
3.
4.
A. L. Geller A. V. Kharchenko E. D. Kachura S. V. Kovalenko V. T. Alekseenko 《Metal Science and Heat Treatment》1995,37(5):187-191
Large-sin parts are usually produced from steels with high hardenability. Intermediate-carbon improved chromium-nickel steels containing 1–3% Ni are used successfully for this purpose in Ukraine and in foreign countries. However, nickel is an expensive and scarce alloying element. The present work is devoted to steels with different compositions with the aim of choosing the most suitable one for large-size parts. The effect of alloying elements on the hardenability and mechanical properties of steels is investigated. A mathematical model is obtained.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 13–17, May, 1995. 相似文献
5.
Ahmed Fadl Zongqin Zhang Sebastian Geller Jonas Tölke Manfred Krafczyk Donna Meyer 《Microsystem Technologies》2009,15(9):1379-1387
The efficiency of the valve-less rectification micropump depends primarily on the microfluidic diodicity (the ratio of the
backward pressure drop to the forward pressure drop). In this study, different rectifying structures, including the conventional
structures (nozzle/diffuser and Tesla structures), were investigated at very low Reynolds numbers (between 0.2 and 60). The
rectifying structures were characterized with respect to their design, and a numerical approach was illustrated to calculate
the diodicity for the rectifying structures. In this study, the microfluidic diodicity was evaluated numerically for different
rectifying structures including half circle, semicircle, heart, triangle, bifurcation, nozzle/diffuser, and Tesla structures.
The Lattice Boltzmann Method (LBM) was utilized as a numerical method to simulate the fluid flow in the microscale. The results
suggest that at very low Reynolds number flow, rectification and multifunction micropumping may be achievable by using a number
of the presented structures. The results for the conventional structures agree with the reported results. 相似文献
6.
Ashish Mehta James Geller Yehoshua Perl Erich Neuhold 《The VLDB Journal The International Journal on Very Large Data Bases》1998,7(1):25-47
A path-method is used as a mechanism in object-oriented databases (OODBs) to retrieve or to update information relevant to one class that
is not stored with that class but with some other class. A path-method is a method which traverses from one class through
a chain of connections between classes and accesses information at another class. However, it is a difficult task for a casual
user or even an application programmer to write path-methods to facilitate queries. This is because it might require comprehensive
knowledge of many classes of the conceptual schema that are not directly involved in the query, and therefore may not even
be included in a user's (incomplete) view about the contents of the database. We have developed a system, called path-method generator (PMG), which generates path-methods automatically according to a user's database-manipulating requests. The PMG offers the
user one of the possible path-methods and the user verifies from his knowledge of the intended purpose of the request whether
that path-method is the desired one. If the path method is rejected, then the user can utilize his now increased knowledge
about the database to request (with additional parameters given) another offer from the PMG. The PMG is based on access weights attached to the connections between classes and precomputed access relevance between every pair of classes of the OODB. Specific rules for access weight assignment and algorithms for computing access
relevance appeared in our previous papers [MGPF92, MGPF93, MGPF96]. In this paper, we present a variety of traversal algorithms
based on access weights and precomputed access relevance. Experiments identify some of these algorithms as very successful
in generating most desired path-methods. The PMG system utilizes these successful algorithms and is thus an efficient tool
for aiding the user with the difficult task of querying and updating a large OODB.
Received July 19, 1993 / Accepted May 16, 1997 相似文献
7.
8.
The interactions of the 936-species phages sk1, jj50, and 64 with the cell surface of Lactococcus lactis LM0230 were analyzed. Cell envelopes (walls + plasma membrane), cell wall, or plasma membrane from L. lactis ssp. lactis LM0230 each inactivated the phages in vitro. However, other 936-species phages kh and P008, which do not infect strain LM0230, were not inactivated by any of the subcellular fractions. Treating cell walls or plasma membrane with the cell wall hydrolase mutanolysin eliminated inactivation of phage sk1. This suggested that intact cell wall fragments were required for inactivation. A role for plasma membrane in phage sk1 inactivation was further investigated. Boiling, washing in 2 M KCl, 8 M urea, or 0.1 M Na(2)CO(3)/pH 11, or treating the plasma membrane with proteases did not reduce adsorption or inactivation of phage. Adding lipoteichoic acid or antibodies to lipoteichoic acid did not reduce inactivation of phage in a mixture with membrane, suggesting that lipoteichoic acid was not involved. Inactivation by envelopes or cell wall correlated with ejection of DNA from the phage sk1 capsid. Although calcium is required for plaque formation, it was not required for adsorption, inactivation, or ejection of phage DNA by envelopes or cell wall. The results suggest that at least for phages sk1, jj50, and 64, adsorption and phage DNA injection into the host does not require a host membrane protein or lipoteichoic acid, and that cell wall components are sufficient for these initial steps of phage infection. 相似文献
9.
In an attempt to establish a standardized rating system for CT of the paranasal sinuses, the Committee on Rhinology and Paranasal Sinus Disease of the American Academy of Otolaryngology-Head and Neck Surgery instituted a protocol for the review of sinus CT scans at six international sites. Fifty identical scans were rated by four otolaryngologists at each site according to five established sinus CT staging systems. Twenty of 24 reviewers repeated the rating session at least 1 week later to determine intrarater variability. The number of CT scans that could not be classified by a particular rating system ranged from 1.3% to 5.5%. The range of intrarater agreement (kappa = 0.39 to 0.74) exceeded that of interrater agreement (kappa = 0.18 to 0.49). A skewed distribution of CT scans resulted in a system with high rater agreement but poor ability to differentiate among disease states. The use of a numeric rating system to assign a score to each scan produced a comprehensive and disease-sensitive system, but one with low rater agreement. A precise definition of mucosal thickening in terms of millimeters appeared to enhance the raters' ability to assign stage and improve a system's comprehensiveness and reproducibility. On the basis of these findings, recommendations are made for the use of CT rating systems to study clinical outcomes in patients with chronic sinusitis. 相似文献
10.