全文获取类型
收费全文 | 2684篇 |
免费 | 15篇 |
国内免费 | 6篇 |
学科分类
工业技术 | 2705篇 |
出版年
2023年 | 8篇 |
2022年 | 10篇 |
2021年 | 9篇 |
2020年 | 12篇 |
2019年 | 12篇 |
2018年 | 11篇 |
2017年 | 9篇 |
2016年 | 17篇 |
2015年 | 13篇 |
2014年 | 22篇 |
2013年 | 56篇 |
2012年 | 34篇 |
2011年 | 59篇 |
2010年 | 38篇 |
2009年 | 41篇 |
2008年 | 46篇 |
2007年 | 41篇 |
2006年 | 32篇 |
2005年 | 26篇 |
2004年 | 30篇 |
2003年 | 42篇 |
2002年 | 29篇 |
2001年 | 19篇 |
2000年 | 27篇 |
1999年 | 66篇 |
1998年 | 547篇 |
1997年 | 312篇 |
1996年 | 230篇 |
1995年 | 115篇 |
1994年 | 105篇 |
1993年 | 122篇 |
1992年 | 27篇 |
1991年 | 36篇 |
1990年 | 28篇 |
1989年 | 30篇 |
1988年 | 32篇 |
1987年 | 55篇 |
1986年 | 36篇 |
1985年 | 38篇 |
1984年 | 16篇 |
1983年 | 8篇 |
1982年 | 16篇 |
1981年 | 15篇 |
1980年 | 16篇 |
1979年 | 8篇 |
1978年 | 7篇 |
1977年 | 34篇 |
1976年 | 76篇 |
1941年 | 6篇 |
1935年 | 5篇 |
排序方式: 共有2705条查询结果,搜索用时 0 毫秒
61.
证券内幕交易是证券市场中经常发生的、危害极大的一种经济犯罪行为。本文主要论述了内幕交易的犯罪构成,从内幕信息、内幕信息知情人员的范围、内幕交易的主观方面、客观方面等环节重新梳理内幕交易罪。 相似文献
62.
Optimal shape design using numerical techniques is an increasingly useful engineering tool. Generalized or layout optimal design where the topology of the object is not fixed is one of the emerging applications. These problems are numerically difficult to solve due to the large number of design variables and equality/inequality constraints. Solutions have focused primarily on compliance based minimization under a fixed volume. A more usual engineering approach would be one of minimizing the volume under a stress or deflection constraint. This, however, can lead to problems as stress is a local quantity and volume minimization of multiple load cases under stress constraints may not result in the stiffest design for the remaining material. The approach adopted here is based on a differential rate equation governed by a local operator that defines the state of each element at each time step. This algorithm forms the optimality criteria for the problem. To satisfy the global stress constraints, a feedback derivative is used, analogous to a Lagrange multiplier. The original method for a single load case developed by these authors is extended to deal with multiple load cases. Additionally, a discussion of the global behaviour is included. 相似文献
63.
The popularity of digital microscopy and tissue microarrays allow the use of high-throughput imaging for pathology research. To coordinate with this new technique, it is essential to automate the process of extracting information from such high amount of images. In this paper, we present a new model called the Subspace Mumford-Shah model for texture segmentation of microscopic endometrial images. The model incorporates subspace clustering techniques into a Mumford-Shah model to solve texture segmentation problems. The method first uses a supervised procedure to determine several optimal subspaces. These subspaces are then embedded into a Mumford-Shah objective function so that each segment of the optimal partition is homogeneous in its own subspace. The method outperforms a widely used method in bioimaging community called k-means segmentation since it can separate textures which are less separated in the full feature space, which confirm the usefulness of subspace clustering in texture segmentation. Experimental results also show that the proposed method is well performed on diagnosing premalignant endometrial disease and is very practical for segmenting image set sharing similar properties. 相似文献
64.
The purpose of this study was to demonstrate the presence of vinculin and alpha2 integrin in chondrocytes in situ and epithelial cells. We also determined that the appropriate fixation and extraction protocols for immunohistochemistry and laser scanning confocal microscopy for an integral membrane protein and an actin-associated protein in cultured cells and whole tissue was different. Cultured epithelial cells, whole mount human cornea and avian cartilage were fixed and prepared using a number of standard procedures used for indirect fluorescence immunohistochemistry. The distribution of vinculin was cell-type and fixation-specific. Chondrocytes and cultured epithelial cells demonstrated vinculin in areas that appear to be associated with filamentous actin. Vinculin was associated with cell membranes in human cornea. The expression of alpha2 integrin observed in chondrocytes fixed with methanol, paraformaldehyde, or formaldehyde is consistent with its role in cell-substrate interaction, but may also suggest a role in dividing and differentiating cells. The localization of alpha2 integrin in human corneal epithelia supports its role as a cell-cell adhesion molecule. The cytoplasmic distribution of vinculin and alpha2 integrin in tissues fixed without detergent extraction suggests that the fixation step may be sufficient for antibody penetration and antigen extraction. These studies are the first report of vinculin and alpha2 integrin in embryonic chondrocytes. In addition we have shown that confocal laser scanning microscopy combined with proper fixation and extraction protocols may optimize the localization of antigens in cultured and whole mount cells. 相似文献
65.
Y Kawano Y Takaue P Law T Watanabe T Abe Y Okamoto A Makimoto J Sato R Nakagawa T Kajiume A Hirao A Watanabe Y Kuroda 《Canadian Metallurgical Quarterly》1998,22(10):1011-1017
The quality of population-based cancer registries has been measured by the indices of the proportion of total incident cases (DCO%) registered by death certificate only (DCO), and the ratio of incidence to mortality (I/D ratio). Recently it has been recommended that DCO% should be used as an index for the reliability of diagnosing cancers and that the proportion of cases first notified via death certificate (DCN, DCN%) be used as an index for the completeness of registration. Parkin introduced a method to estimate the registration rate, the estimated proportion of the "true incidence" that are registered in population-based registries. We recommend a modified method for estimating the registration rate for cancer registries where DCN% is relatively high, as it is in Japan, as Parkin's method may overestimate the registration rate. The method is as follows: the registration rate = (1-DCN% x 1/D ratio)/(1-DCN%). The registration rates at the Osaka Cancer Registry between 1966 and 1992 were estimated using our method. During this period, the yearly registration rate was 74.6-78.4% for males and 69.1-73.3% for females. When the cancer cases were looked at according to site, the yearly registration rate was 74.2-81.6% for stomach cancer, 81.2-89.3% for lung cancer, and 71.3-76.9% for uterine cancer. These results show that the registration rate is high for cancers that have an unfavorable prognosis and low for cancers that have a favorable prognosis. We recommend that all cancer registries in Japan calculate the completeness of registration by utilizing DCN defined as the sum of DCO plus cases not reported as cancer but with supportive clinical information of such obtained through survey of the registry for DCN. 相似文献
66.
Hua-Li Jian Sandnes F.E. Yo-Ping Huang Li Cai Law K.M.Y. 《Education, IEEE Transactions on》2008,51(2):157-165
Course work plagiarism among university students is often attributed to ignorance about plagiarism or an assignment's level of difficulty. Students submit other people's work when they are unable to solve an assignment themselves. This study, based on 233 student responses from four cultural regions, investigates three aspects of academic dishonesty. First, the study identifies students' preferred strategies for managing perceptually too difficult course work. Second, students' preferences for responding to help from fellow students are investigated. Finally, the study measures students' preferences for choosing side in ethical conflicts. Seven strategies for managing difficult course work, six strategies for responding to requests for help, and five key parties in ethical conflicts are studied using a pair-wise comparison method. The results show that students prefer to collaborate and use the Internet. The impact of the teacher is smaller than expected. Factors including cultural origin, gender, level of study, and field of study have limited impact. 相似文献
67.
68.
69.
70.