全文获取类型
收费全文 | 1664篇 |
免费 | 12篇 |
专业分类
电工技术 | 12篇 |
化学工业 | 53篇 |
机械仪表 | 15篇 |
建筑科学 | 15篇 |
能源动力 | 3篇 |
轻工业 | 45篇 |
石油天然气 | 2篇 |
无线电 | 24篇 |
一般工业技术 | 24篇 |
冶金工业 | 1429篇 |
原子能技术 | 2篇 |
自动化技术 | 52篇 |
出版年
2019年 | 3篇 |
2017年 | 11篇 |
2016年 | 5篇 |
2013年 | 10篇 |
2012年 | 7篇 |
2011年 | 6篇 |
2010年 | 7篇 |
2009年 | 7篇 |
2008年 | 18篇 |
2007年 | 13篇 |
2006年 | 9篇 |
2005年 | 6篇 |
2004年 | 12篇 |
2003年 | 6篇 |
2002年 | 6篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 43篇 |
1998年 | 436篇 |
1997年 | 256篇 |
1996年 | 146篇 |
1995年 | 96篇 |
1994年 | 70篇 |
1993年 | 103篇 |
1992年 | 10篇 |
1991年 | 30篇 |
1990年 | 29篇 |
1989年 | 19篇 |
1988年 | 21篇 |
1987年 | 24篇 |
1986年 | 13篇 |
1985年 | 13篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 7篇 |
1981年 | 10篇 |
1980年 | 12篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1977年 | 35篇 |
1976年 | 89篇 |
1975年 | 5篇 |
1973年 | 4篇 |
1971年 | 3篇 |
1970年 | 6篇 |
1963年 | 3篇 |
1962年 | 2篇 |
1961年 | 2篇 |
1959年 | 3篇 |
1955年 | 3篇 |
排序方式: 共有1676条查询结果,搜索用时 15 毫秒
61.
The isolation of Actinomyces viscosus from two patients is described. One was a case of multiple myeloma, the organism being found on blood culture; the other was a patient with a submandibular abscess. These are believed to be the first such isolations of A. viscosus in this country. 相似文献
62.
We have reported our experience with splenectomy in fifty patients less than fourteen years old. The indications, results, and complications were enumerated. These data were then correlated with the recent literature regarding pediatric splenctomy. Of special note is the problem of immunologic incompetency associated with splenectomy in the patients less than five years old. 相似文献
63.
64.
W Pawlik LL Tague BL Tepperman TA Miller ED Jacobson 《Canadian Metallurgical Quarterly》1977,233(3):E219-E224
Studies were conducted in anesthetized dogs to determine whether the mesenteric vasodilator response to histamine is mediated by H1 receptors alone or whether H2 receptors are also involved in the response. Evidence favoring a role for both receptors included: 1) the vasodilator response to histamine was inhibited by either the H1-receptor antagonist, tripelennamine, or the H2-receptor antagonist, metiamide; 2) both the H1 agonist, 2-methylhistamine, and the H2 agonist, 4-methylhistamine, induced dilator responses in the mesenteric circulation; and 3) two temporal patterns of vasodilation could be distinguished, namely a transient spike and subsequent fade of blood flow (seen with either the H1 agonist or with histamine after H2-receptor blockade) and a sustained and stable increase in flow (seen with either the H2 agonist or with histamine after H1 blockade). Metiamide appeared to be a potent inhibitor of the mesenteric vasodilator response to histamine at least equal to tripelennamine. 相似文献
65.
This study investigates the writing stylechange of two Turkish authors, Çetin Altanand Yaar Kemal, in their old and newworks using respectively their newspapercolumns and novels. The style markers are thefrequencies of word lengths in both text andvocabulary, and the rate of usage of mostfrequent words. For both authors, t-tests andlogistic regressions show that the length ofthe words in new works is significantly longerthan that of the old. The principal componentanalyses graphically illustrate the separationbetween old and new texts. The works arecorrectly categorized as old or new with 75 to100% accuracy and 92% average accuracy usingdiscriminant analysis-based cross validation. The results imply higher time gap may havepositive impact in separation andcategorization. For Altan a regressionanalysis demonstrates a decrease in averageword length as the age of his column increases. One interesting observation is that for oneword each author has similar preference changesover time. 相似文献
66.
67.
Twenty-one cases of mammary tuberculosis are reported and the attendant clinical and histological difficulties described. It is probable that contemporary clinicians would now make the clinical diagnosis of breast abscess or carcinoma. Furthermore, the histological features (without demonstration or culture of the organism) may be confused with those granulomatous epithelloid reactions seen in mammary duct ectasia (comedo cell mastitis, plasma cell mastitis) and in traumatic fat necrosis. 相似文献
68.
Building useful software relies on understanding users, their goals, and their problems, and on determining the software that will help them reach those goals and solve those problems. User centricity isn't just caring about users or asking them what they want. It's understanding them and collaborating effectively with them to help make informed choices about what software to build. 相似文献
69.
Daunorubicin‐Loaded DNA Origami Nanostructures Circumvent Drug‐Resistance Mechanisms in a Leukemia Model
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Patrick D. Halley Christopher R. Lucas Emily M. McWilliams Matthew J. Webber Randy A. Patton Comert. Kural David M. Lucas John C. Byrd Carlos E. Castro 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(3):308-320
Many cancers show primary or acquired drug resistance due to the overexpression of efflux pumps. A novel mechanism to circumvent this is to integrate drugs, such as anthracycline antibiotics, with nanoparticle delivery vehicles that can bypass intrinsic tumor drug‐resistance mechanisms. DNA nanoparticles serve as an efficient binding platform for intercalating drugs (e.g., anthracyclines doxorubicin and daunorubicin, which are widely used to treat acute leukemias) and enable precise structure design and chemical modifications, for example, for incorporating targeting capabilities. Here, DNA nanostructures are utilized to circumvent daunorubicin drug resistance at clinically relevant doses in a leukemia cell line model. The fabrication of a rod‐like DNA origami drug carrier is reported that can be controllably loaded with daunorubicin. It is further directly verified that nanostructure‐mediated daunorubicin delivery leads to increased drug entry and retention in cells relative to free daunorubicin at equal concentrations, which yields significantly enhanced drug efficacy. Our results indicate that DNA origami nanostructures can circumvent efflux‐pump‐mediated drug resistance in leukemia cells at clinically relevant drug concentrations and provide a robust DNA nanostructure design that could be implemented in a wide range of cellular applications due to its remarkably fast self‐assembly (≈5 min) and excellent stability in cell culture conditions. 相似文献
70.
A new parametric observer-based approach for robust fault detection in multivariable linear systems with unknown disturbances is proposed. The residual is generated through utilizing a Luenberger function observer. By using a parametric solution to a class of generalized Sylvester matrix equations, a parametrization is proposed for the residual generator on the basis of a Luenberger function observer. By further properly constraining the design parameters provided in the Luenberger observer design, the effect of the unknown disturbance is decoupled from the residual signal. The proposed approach provides all the degrees of freedom and is demonstrated to be simple and effective. 相似文献