首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2277篇
  免费   19篇
  国内免费   2篇
电工技术   5篇
化学工业   98篇
金属工艺   17篇
机械仪表   36篇
建筑科学   25篇
矿业工程   1篇
能源动力   32篇
轻工业   24篇
水利工程   8篇
石油天然气   4篇
无线电   47篇
一般工业技术   90篇
冶金工业   1797篇
原子能技术   3篇
自动化技术   111篇
  2023年   10篇
  2022年   17篇
  2021年   27篇
  2020年   24篇
  2019年   24篇
  2018年   29篇
  2017年   16篇
  2016年   40篇
  2015年   20篇
  2014年   18篇
  2013年   39篇
  2012年   43篇
  2011年   43篇
  2010年   28篇
  2009年   27篇
  2008年   20篇
  2007年   8篇
  2006年   12篇
  2005年   10篇
  2004年   8篇
  2003年   11篇
  2002年   5篇
  2001年   2篇
  2000年   5篇
  1999年   75篇
  1998年   602篇
  1997年   301篇
  1996年   204篇
  1995年   126篇
  1994年   110篇
  1993年   104篇
  1992年   6篇
  1991年   17篇
  1990年   26篇
  1989年   12篇
  1988年   20篇
  1987年   8篇
  1986年   15篇
  1985年   9篇
  1983年   2篇
  1982年   12篇
  1981年   12篇
  1980年   10篇
  1979年   4篇
  1978年   5篇
  1977年   42篇
  1976年   83篇
  1975年   3篇
  1971年   1篇
  1959年   1篇
排序方式: 共有2298条查询结果,搜索用时 31 毫秒
71.
This paper explores how land-based financing mechanisms are currently used in Ho Chi Minh City as a public-private funding strategy. The Land-for-Infrastructure (LFI) mechanism appears as a solution to produce infrastructures. We found that the implementation of the LFI mechanism remains difficult, but eventually can lead to success. By ‘trial-error-transcend,’ the City managed to build two essential roads while the developers received attractive investment opportunities in urban development. This mechanism cannot, however, be seen as a panacea for the local authorities due to constraints to replicate it and potential undesired ‘side effects.’  相似文献   
72.
The Journal of Supercomputing - The networking infrastructure of a software-defined network (SDN) requires further study to achieve continuity and high availability of data transactions for cloud...  相似文献   
73.
The magnetoelectric sensor based on (Fe80Co20)78Si12B10/PZT laminates is designed, fabricated and characterized for determining dc and ac magnetic-field strengths as well as field orientations. At low dc magnetic-fields, a ME-voltage response (dVME/dH) as high as 2 mV/Oe is achieved. The linear relation VME(hac) with a slope of dVME/dhac of 17 mV/Oe shows a great ability to self-powered detecting low ac magnetic-fields. The field orientation can be detected by using the sinusoidal dependence of the magnetoelectric voltage. The sensor is promising not only for microtesla magnetic-field sensing but also for magnetic biosensor applications.  相似文献   
74.
Microglial interaction with amyloid fibrils in the brains of Alzheimer's and prion disease patients results in the inflammatory activation of these cells. We observed that primary microglial cultures and the THP-1 monocytic cell line are stimulated by fibrillar beta-amyloid and prion peptides to activate identical tyrosine kinase-dependent inflammatory signal transduction cascades. The tyrosine kinases Lyn and Syk are activated by the fibrillar peptides and initiate a signaling cascade resulting in a transient release of intracellular calcium that results in the activation of classical PKC and the recently described calcium-sensitive tyrosine kinase PYK2. Activation of the MAP kinases ERK1 and ERK2 follows as a subsequent downstream signaling event. We demonstrate that PYK2 is positioned downstream of Lyn, Syk, and PKC. PKC is a necessary intermediate required for ERK activation. Importantly, the signaling response elicited by beta-amyloid and prion fibrils leads to the production of neurotoxic products. We have demonstrated in a tissue culture model that conditioned media from beta-amyloid- and prion-stimulated microglia or from THP-1 monocytes are neurotoxic to mouse cortical neurons. This toxicity can be ameliorated by treating THP-1 cells with specific enzyme inhibitors that target various components of the signal transduction pathway linked to the inflammatory responses.  相似文献   
75.
OBJECTIVE: To measure grocery chain pharmacists' work-related behaviors to assess the impact of a Pharmaceutical Care Certificate Program (PCCP) and other future interventions intended to alter pharmacists' practice behaviors. DESIGN: This study used multidimensional work sampling (MWS), a work measurement methodology that breaks "work" into three components: activity (what was done), contact (with whom the activity was performed), and function (the purpose or objective of the activity). Pharmacists were signaled at random intervals during the workday by a random signal generator. A selection was made from a list of items in each of the three dimensions of work to form an activity-contact-function combination code that described the work-related behavior at that point in time. SETTING AND PARTICIPANTS: Pharmacists in 15 grocery chain stores in the Indianapolis area; 20 pharmacists were enrolled in Purdue University's PCCP and 10 served as controls. Data were collected for a period of six weeks during April through June 1997 before the beginning of the PCCP program. MAIN OUTCOME MEASURES: Pharmacists' work-related behaviors. RESULTS: Writing/keyboarding was the most frequently recorded activity (22%), followed by one-to-one meetings (21.6%), and drug preparation (18%). Pharmacists spent most of their time working alone (62.9%), while a smaller but still substantial proportion of time was spent interacting with patients (17.9%). The most frequently recorded purpose (i.e., function) of pharmacists' activities was drug distribution (23.9%), followed by personal time (12.4%), receiving or transferring a medication order (10.2%), and patient counseling (6.6%). Out of a possible, 1,760 activity-contact-function combinations, 10 accounted for 46.3% of all reported observations, with "Prepare drug-Self-Drug distribution" representing the most frequently recorded activity-contact-function combination (15.7%). CONCLUSION: MWS is useful in helping grocery chain management better understand how pharmacy personnel are currently being utilized. This study provides a baseline for evaluating the impact of training programs or other alterations in the practice environment on pharmacists' work-related behaviors.  相似文献   
76.
Massage therapy is older than recorded time, and rubbing was the primary form of medicine until the pharmaceutical revolution of the 1940s. Popularized again as part of the alternative medicine movement, massage therapy has recently received empirical support for facilitating growth, reducing pain, increasing alertness, diminishing depression, and enhancing immune function. In this article studies are reviewed that document these effects, and models are proposed for potential underlying mechanisms.  相似文献   
77.
78.
BB-10010 is a variant of the human form of macrophage inflammatory protein-1alpha (MIP-1alpha), which has been shown in mice to block the entry of hematopoietic stem cells into S-phase and to increase their self-renewal capacity during recovery from cytotoxic damage. Its use may constitute a novel approach for protecting the quality of the stem cell population and its capacity to regenerate after periods of cytotoxic treatment. Thirty patients with locally advanced or metastatic breast cancer were entered into the first randomized, parallel group controlled phase II study. This was designed to evaluate the potential myeloprotective effects of a 7-day regimen of BB-10010 administered to patients receiving six cycles of 5-fluorouracil (5-FU), adriamycin, and cyclophosphamide (FAC) chemotherapy. Patients were randomized, 10 receiving 100 microgram/kg BB-10010, 11 receiving 30 microgram/kg BB-10010, and nine control patients receiving no BB-10010. BB-10010 was well-tolerated in all patients with no severe adverse events related to the drug. Episodes of febrile neutropenia complicated only 4% of the treatment cycles and there was no difference in incidence between the treated and nontreated groups. Studies to assess the generation of progenitor cells in long-term bone marrow cultures were performed immediately preceding chemotherapy and at the end of six dosing cycles in 18 patients. Circulating neutrophils, platelets, CD 34(+) cells, and granulocyte/macrophage colony-forming cell (GM-CFC) levels were determined at serial time points in cycles 1, 3, and 6. The results showed similar hemoglobin and platelet kinetics in all three groups. On completion of the six treatment cycles, the average pretreatment neutrophil levels were reduced from 5.3 to 1.7 x 10(9)/L in the control patients and from 4.3 to 1.9 and 4.5 to 2.5 x 10(9)/L in the 30/100 microgram/kg BB-10010 groups, respectively. Relative to their pretreatment values, 50% of the patients receiving BB-10010 completed the treatment with neutrophil values significantly higher than any of the controls (P = .02). Mobilization of GM-CFC was enhanced by BB-10010 with an additional fivefold increase over that generated by chemotherapy alone, giving a maximal 25-fold increase over pretreatment values. Bone marrow progenitor assays before and after this standard regimen of chemotherapy indicated little long-term cumulative impairment to recovery from chemotherapy. Despite the limited cumulative damage to the bone marrow, which may have minimized the protective value of BB-10010 during this regimen of chemotherapy, better recovery of neutrophils in the later treatment cycles with BB-10010 was indicated in a number of patients.  相似文献   
79.
80.
Effective Hamiltonian for the superconducting Cu oxides   总被引:1,自引:0,他引:1  
  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号