全文获取类型
收费全文 | 1257篇 |
免费 | 1篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 20篇 |
金属工艺 | 4篇 |
机械仪表 | 2篇 |
建筑科学 | 21篇 |
能源动力 | 3篇 |
轻工业 | 4篇 |
水利工程 | 2篇 |
石油天然气 | 4篇 |
无线电 | 2篇 |
一般工业技术 | 24篇 |
冶金工业 | 1157篇 |
原子能技术 | 2篇 |
自动化技术 | 11篇 |
出版年
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 6篇 |
2012年 | 2篇 |
2011年 | 8篇 |
2010年 | 7篇 |
2009年 | 6篇 |
2008年 | 12篇 |
2007年 | 6篇 |
2006年 | 4篇 |
2005年 | 6篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 7篇 |
2001年 | 3篇 |
2000年 | 6篇 |
1999年 | 44篇 |
1998年 | 330篇 |
1997年 | 216篇 |
1996年 | 122篇 |
1995年 | 53篇 |
1994年 | 64篇 |
1993年 | 69篇 |
1992年 | 17篇 |
1991年 | 8篇 |
1990年 | 17篇 |
1989年 | 15篇 |
1988年 | 19篇 |
1987年 | 22篇 |
1986年 | 7篇 |
1985年 | 14篇 |
1984年 | 4篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 11篇 |
1979年 | 1篇 |
1978年 | 6篇 |
1977年 | 29篇 |
1976年 | 78篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1969年 | 2篇 |
1968年 | 2篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1965年 | 2篇 |
1964年 | 1篇 |
1960年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1258条查询结果,搜索用时 562 毫秒
91.
92.
93.
The authors examined relations between the Big Five personality traits and academic outcomes, specifically SAT scores and grade-point average (GPA). Openness was the strongest predictor of SAT verbal scores, and Conscientiousness was the strongest predictor of both high school and college GPA. These relations replicated across 4 independent samples and across 4 different personality inventories. Further analyses showed that Conscientiousness predicted college GPA, even after controlling for high school GPA and SAT scores, and that the relation between Conscientiousness and college GPA was mediated, both concurrently and longitudinally, by increased academic effort and higher levels of perceived academic ability. The relation between Openness and SAT verbal scores was independent of academic achievement and was mediated, both concurrently and longitudinally, by perceived verbal intelligence. Together, these findings show that personality traits have independent and incremental effects on academic outcomes, even after controlling for traditional predictors of those outcomes. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
94.
95.
JH Tuerlings MJ Ligtenberg JA Kremer M Siers EJ Meuleman DD Braat LH Hoefsloot HM Merkus HG Brunner 《Canadian Metallurgical Quarterly》1998,13(8):2098-2101
Follicle stimulating hormone (FSH) is considered to be essential for spermatogenesis. Therefore, genetic abnormalities of FSH signalling on testicular Sertoli cells would be expected to affect sperm production negatively in males. Inactivating FSH receptor mutations have been reported earlier in both males and females. All affected males had elevated FSH serum concentrations and abnormal sperm parameters. We postulated that inactivating FSH receptor mutations might be a cause of oligozoospermia or azoospermia and reviewed the clinical data of 151 male intracytoplasmic sperm injection (ICSI) candidates with special attention to FSH serum concentrations. The exclusion criteria for mutation screening of the FSH receptor gene were: a history of operative sterilization or testicular malignancy, congenital abnormality other than cryptorchidism, and a chromosomal aberration or a Y-chromosome microdeletion. The inclusion criteria were: male (ICSI candidate) with azoospermia or oligoasthenoteratozoospermia (OAT) and elevated FSH serum concentrations. In total, 23 males with OAT and five males with azoospermia were tested for mutations of the coding sequences and the intron-exon boundaries of the FSH receptor gene by polymerase chain reaction (PCR) followed by single strand conformation polymorphism analysis (SSCP). Neutral polymorphisms were readily detected using this technique in both probands and controls. None of the 28 selected patients showed a pathogenic FSH receptor mutation. Mutations in the FSH receptor gene are not a common cause of infertility in ICSI candidates. 相似文献
96.
DM Panicek LH Schwartz DD Dershaw MC Ercolani RA Castellino 《Canadian Metallurgical Quarterly》1998,170(3):577-581
In light of the recently described experimental technique of in vivo bone reconstitution with biotechnologic methods (from bone marrow stromal cells) and the prefabrication flap procedures, the possibility to obtain autologous bone growth in a myocutaneous flap, thus creating a composite osteomyocutaneous preformed flap, is postulated. Human bone marrow stromal cells were delivered into the latissimus dorsi of athymic mice by a porous hydroxyapatite ceramic model. Eight weeks after the implantation, histologic examination revealed the presence of spongious bone tissue. A simple myocutaneous flap was thus transformed into a composite osteomyocutaneous flap. This flap is called the biotechnologic prefabricated flap, because it was the result of ex vivo expanded osteogenic precursor cells and in vivo bone tissue neoformation. The shape of the bone flap was exactly the same as the shape of the ceramic model used. A possible clinical application may be the correction of skeletal defects. The advantages of this procedure are simple surgical execution, the possibility of preshaping the graft to the exact characteristics of the defect, and the availability of autogenous donor tissue without donor site morbidity. 相似文献
97.
Bruce Robins 《Refocus》2006,7(3):162-39
Remote rural communities in developing countries are at a similar economic stage of development as was the developed world more than 100 years ago when electricity was used for more than 50 years for lighting and radio only. Not until people could afford refrigerators did electricity demand grow. Without direct capital subsidies by governments and cross subsidies by utilities the developed world would not be as developed as it currently is and certainly not those communities outside major cities and towns. Many rural areas in the developed world would be in a similar energy plight to those currently in the developing world! There currently is no technology that can meet a subsidy free energy supply anywhere in remote rural communities. The least cost option to meet the basic energy needs for the remote developing world is a properly designed solar system (systems designed up to an availability level not down to a price). To supply the one billion people without access to electricity would cost about US$112 billion (2005 $) in total subsidies using solar. But this will be less than the US$450 billion (2005) subsidy to meet their basic lighting needs using diesel energy.The user pays principle might work for McDonalds but 20 years working in developing countries has clearly demonstrated that there is something dramatically wrong with the current economic paradigms where basic infrastructure is required. It should not be the Private Sector that funds the development of remote rural lighting, they have demonstrated that they can only deliver too little too late, but the Public sector through their existing utilities with government direct subsidies if another generation is not to be lost to development. To demonstrate the need for a paradigm shift, over the past 20 years I have implemented and installed solar projects worth more than US$100million in many developing countries, but none with their utilities or energy departments. All the projects have been with rural development authorities that recognised the immediate need of their constituents and were not at all fussed by the concept of subsidisation. They actually know what it was like on the ground. Something that many energy authorities and utilities I fear have no idea about. 相似文献
98.
LH Greiner DA Snowdon 《Canadian Metallurgical Quarterly》1997,277(22):1757; author reply 1758-1757; author reply 1759
99.
JM Coll RJ Hickey EA Cronkey HY Jiang L Schnaper MY Lee L Uitto JE Syvaoja LH Malkas 《Canadian Metallurgical Quarterly》1997,9(11-12):629-639
We have previously described the isolation and characterization of an intact multiprotein complex for DNA replication, designated the DNA synthesome, from human breast cancer cells and biopsied human breast tumor tissue. The purified DNA synthesome was observed to fully support DNA replication in vitro. We had also proposed a model for the breast cell DNA synthesome, in which DNA polymerases alpha, delta, and epsilon, DNA primase, and replication factor C (RF-C) represent members of the core component, or tightly associated, proteins of the complex. This model was based on the observed fractionation, chromatographic, and sedimentation profiles for these proteins. We report here that poly(ADP-ribose)polymerase (PARP) and DNA ligase 1 are also members of the breast cell DNA synthesome core component. More importantly, in this report we present the results of coimmunoprecipitation studies that were designed to map the protein-protein interactions between several members of the core component of the DNA synthesome. Consistent with our proposed model for the breast cell DNA synthesome, our data indicate that DNA polymerases alpha and delta, DNA primase, RF-C, as well as proliferating cell nuclear antigen (PCNA), tightly associate with each other in the complex, whereas DNA polymerase epsilon, PARP, and several other components were found to interact with the synthesome via a direct contact with only PCNA or DNA polymerase alpha. The association of PARP with the synthesome core suggests that this protein may serve a regulatory function in the complex. Also, the coimmunoprecipitation studies suggest that the three DNA polymerases alpha, delta, and epsilon all participate in the replication of breast cell DNA. To our knowledge this is the first report ever to describe the close physical association of polypeptides constituting the intact human breast cell DNA replication apparatus. 相似文献
100.
EK Yeong R Mann LH Engrav M Goldberg V Cain B Costa M Moore D Nakamura J Lee 《Canadian Metallurgical Quarterly》1997,18(4):353-5; discussion 352
The subjective assessment of scar appearance is a widely used method in the evaluation of burn outcomes and the efficacy of treatment methods. The purpose of this study is to design a numeric scar-rating scale with better interrater reliability than has previously been reported. The rating scale assesses scar surface, thickness, border height, and color differences between a scar and the adjacent normal skin. Eight raters were trained with use of a standardized set of photographs that provide examples of the scores to be assigned to each level of severity of each scar characteristic. The raters then rated 10 photographs of different scars, referring to the teaching set of pictures for comparison. The intraclass correlation (interrater reliability) was 0.94, 0.95, 0.90, and 0.85 for scar surface, border height, thickness, and color, respectively. This rating system has proved to be a useful tool for the evaluation of scar surface, thickness, border height, and color. 相似文献