全文获取类型
收费全文 | 510994篇 |
免费 | 7411篇 |
国内免费 | 1630篇 |
专业分类
电工技术 | 9483篇 |
综合类 | 741篇 |
化学工业 | 76277篇 |
金属工艺 | 16923篇 |
机械仪表 | 14541篇 |
建筑科学 | 13583篇 |
矿业工程 | 1318篇 |
能源动力 | 14540篇 |
轻工业 | 52565篇 |
水利工程 | 4191篇 |
石油天然气 | 5315篇 |
武器工业 | 13篇 |
无线电 | 65372篇 |
一般工业技术 | 94633篇 |
冶金工业 | 96253篇 |
原子能技术 | 7881篇 |
自动化技术 | 46406篇 |
出版年
2021年 | 3709篇 |
2020年 | 2790篇 |
2019年 | 3487篇 |
2018年 | 5641篇 |
2017年 | 5523篇 |
2016年 | 5933篇 |
2015年 | 4344篇 |
2014年 | 7407篇 |
2013年 | 24082篇 |
2012年 | 12761篇 |
2011年 | 17988篇 |
2010年 | 14010篇 |
2009年 | 15988篇 |
2008年 | 16823篇 |
2007年 | 16829篇 |
2006年 | 15177篇 |
2005年 | 13859篇 |
2004年 | 13518篇 |
2003年 | 13197篇 |
2002年 | 12603篇 |
2001年 | 13059篇 |
2000年 | 12156篇 |
1999年 | 13066篇 |
1998年 | 31229篇 |
1997年 | 22121篇 |
1996年 | 17064篇 |
1995年 | 13143篇 |
1994年 | 11711篇 |
1993年 | 11409篇 |
1992年 | 8339篇 |
1991年 | 7950篇 |
1990年 | 7659篇 |
1989年 | 7392篇 |
1988年 | 7171篇 |
1987年 | 5933篇 |
1986年 | 5940篇 |
1985年 | 7146篇 |
1984年 | 6429篇 |
1983年 | 5986篇 |
1982年 | 5430篇 |
1981年 | 5607篇 |
1980年 | 5193篇 |
1979年 | 4981篇 |
1978年 | 4639篇 |
1977年 | 5546篇 |
1976年 | 7097篇 |
1975年 | 3974篇 |
1974年 | 3761篇 |
1973年 | 3829篇 |
1972年 | 3051篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
973.
Lash Steven J.; Stephens Robert S.; Burden Jennifer L.; Grambow Steven C.; DeMarce Josephine M.; Jones Mark E.; Lozano Brian E.; Jeffreys Amy S.; Fearer Stephanie A.; Horner Ronnie D. 《Canadian Metallurgical Quarterly》2007,21(3):387
Although continuing care is strongly related to positive treatment outcomes for substance use disorder (SUD), participation rates are low and few effective interventions are available. In a randomized clinical trial with 150 participants (97% men), 75 graduates of a residential Veterans Affairs Medical Center SUD program who received an aftercare contract, attendance prompts, and reinforcers (CPR) were compared to 75 graduates who received standard treatment (STX). Among CPR participants, 55% completed at least 3 months of aftercare, compared to 36% in STX. Similarly, CPR participants remained in treatment longer than those in STX (5.5 vs. 4.4 months). Additionally, CPR participants were more likely to be abstinent compared to STX (57% vs. 37%) after 1 year. The CPR intervention offers a practical means to improve adherence among individuals in SUD treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
974.
In its policy rationale for evidence-based practice in psychology (EBPP), the APA Presidential Task Force on Evidence-Based Practice (see record 2006-05893-001) claims to have constituted itself with "scientists and practitioners from a wide range of perspectives and traditions, reflecting the diverse perspectives within the field" (p. 273). We applaud this attention to diversity but contend that an entire perspective of the debate was omitted in the Task Force's newly approved policy and its underlying report. The failure to consider a philosophy of science perspective led the Task Force to make a number of epistemological assumptions that are not based on evidence or rationale and that thus violate the very spirit of evidence-based decision making. In this comment, we reveal a few of these assumptions and discuss their detrimental consequences. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
975.
Presents an obituary for Douglas W. Bray, the inventor of the modern-day assessment center, a method used by thousands of organizations around the world to identify the best people for critical roles and to guide individuals in optimizing their talents. Bray's death in Englewood, New Jersey, on May 9, 2006, ended the extraordinary career of a pioneer in industrial/organizational (I/O) psychology who optimized the interplay of research and application. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
976.
The vicissitudes of the Israeli-Palestinian peace process since 1967 are analyzed using attitudes and related concepts where relevant. The 1967 war returned the two peoples' zero-sum conflict around national identity to its origin as a conflict within the land both peoples claim. Gradually, new attitudes evolved regarding the necessity and possibility of negotiations toward a two-state solution based on mutual recognition, which became the building stones of the 1993 Oslo agreement. Lacking a commitment to a final outcome, the Oslo-based peace process was hampered by reserve options, which increased avoidance at the expense of approach tendencies as the parties moved toward a final agreement. The resulting breakdown of the process in 2000 produced clashing narratives, reflecting different anchors for judgment and classical mirror images. Public support for violence increased, even as public opinion continued to favor a negotiated two-state solution. Reviving the peace process requires mutual reassurance about the availability of a partner for negotiating a principled peace based on a historic compromise that meets the basic needs and validates the identities of both peoples. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
977.
978.
This paper investigates the effect of chelating agents on the bioavailability of Fe and Cu during anaerobic digestion. The results on metal speciation and methane production in anaerobic serum bottles showed that biomass was able to grow in the presence of citrate 1?mM and nitrilotriacetic acid (NTA) 1?mM, suggesting that the binding sites at the cell surface competed efficiently for the metals with the chelating agents added. The presence of free ethylenediaminetetraacetic acid 1?mM inhibited methanogenesis, and this seemed to be related to a loss in metal uptake capacity. Although the addition of soluble microbial products (SMP) did not change metal distribution in anaerobic systems, it caused an increase in the rate of methane production, and it is believed that direct uptake of Cu-SMP complexes was responsible for this increase. The best protection against Cu toxicity occurred when stoichiometric amounts of NTA, which should complex and solubilize most of the Cu, was added, and it is likely that NTA prevented lethal concentrations of Cu from being adsorbed onto the cell and hence internalized. 相似文献
979.
Catherine J. Harrison Yann A. Le Gouellec Robert C. Cheng Amy E. Childress 《Canadian Metallurgical Quarterly》2007,133(11):1004-1014
A dual-staged nanofiltration process is being evaluated as an alternative to reverse osmosis for seawater desalination. The primary goal of this system is to reduce energy consumption while producing potable water at an acceptable recovery rate. Investigation of this system at the bench-scale level focused on membrane surface characterization, ion rejection (including boron, bromide, and iodide rejection), and flux decline. Results from this study showed that two commercially available nanofiltration membranes can effectively desalinate seawater. Although fouling was apparent—and resulted in approximately 20% flux decline over 3 days—a critical flux was not identifiable. Operation of the system at different cross-flow velocities revealed the significance of hydrodynamic conditions on the polarization modulus, and hence on membrane performance. 相似文献
980.