全文获取类型
收费全文 | 6712篇 |
免费 | 136篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 68篇 |
综合类 | 4篇 |
化学工业 | 810篇 |
金属工艺 | 117篇 |
机械仪表 | 122篇 |
建筑科学 | 181篇 |
矿业工程 | 11篇 |
能源动力 | 100篇 |
轻工业 | 528篇 |
水利工程 | 41篇 |
石油天然气 | 20篇 |
无线电 | 652篇 |
一般工业技术 | 794篇 |
冶金工业 | 2834篇 |
原子能技术 | 64篇 |
自动化技术 | 505篇 |
出版年
2022年 | 26篇 |
2021年 | 40篇 |
2020年 | 46篇 |
2019年 | 51篇 |
2018年 | 56篇 |
2017年 | 61篇 |
2016年 | 76篇 |
2015年 | 49篇 |
2014年 | 64篇 |
2013年 | 248篇 |
2012年 | 108篇 |
2011年 | 174篇 |
2010年 | 123篇 |
2009年 | 133篇 |
2008年 | 157篇 |
2007年 | 150篇 |
2006年 | 135篇 |
2005年 | 121篇 |
2004年 | 155篇 |
2003年 | 145篇 |
2002年 | 125篇 |
2001年 | 125篇 |
2000年 | 113篇 |
1999年 | 177篇 |
1998年 | 850篇 |
1997年 | 494篇 |
1996年 | 328篇 |
1995年 | 210篇 |
1994年 | 233篇 |
1993年 | 215篇 |
1992年 | 100篇 |
1991年 | 105篇 |
1990年 | 100篇 |
1989年 | 91篇 |
1988年 | 80篇 |
1987年 | 89篇 |
1986年 | 87篇 |
1985年 | 95篇 |
1984年 | 65篇 |
1983年 | 76篇 |
1982年 | 77篇 |
1981年 | 69篇 |
1980年 | 58篇 |
1979年 | 55篇 |
1978年 | 57篇 |
1977年 | 97篇 |
1976年 | 208篇 |
1975年 | 49篇 |
1974年 | 42篇 |
1973年 | 37篇 |
排序方式: 共有6851条查询结果,搜索用时 0 毫秒
21.
Cigarette smoking continues to be the single, most preventable cause of death and disability in the United States. For individuals who have cancer, continuing to smoke negatively impacts their treatment, survival, and risk for second primary tumors. This review of behavioral and pharmacological approaches to smoking cessation focuses on the recent comprehensive review of cessation interventions by the Agency for Health Care Policy and Research (AHCPR), as well as on new developments in the field. An intervention model is outlined that provides oncologists with a brief and easily implemented method of systematically treating patients who smoke. By assessing patient smoking status, advising smoking patients to quit, and proactively assisting their patients in quitting, oncologists can significantly influence patient health and fulfill their professional and ethical responsibility to address this life-threatening behavior. 相似文献
22.
23.
Chromium metabolism of lactating women was evaluated by measuring diet, breast milk, urine, and serum chromium in 17 subjects 60 d postpartum. Breast milk chromium concentration was similar for the 3 d of collection with a mean +/- SE concentration of 3.54 +/- 0.40 nmol/L (0.18 ng/mL). Dietary intake and urinary chromium values were also similar for each of the 3 collection days. Total chromium intake of lactating mothers (0.79 +/- 0.08 mumol/d) was greater than that of reference female subjects (0.48 +/- 0.02). There was a significant correlation (r = 0.84) between serum chromium and urinary chromium excretion. If a breast milk volume of 715 mL is assumed, chromium intake of exclusively breast-fed infants is < 2% of the estimated safe and adequate daily intake of 10 micrograms. In summary, breast milk chromium content is independent of dietary chromium intake and serum or urinary chromium values. Chromium intake also did not correlate with serum or urine chromium but there was a significant relationship between serum and urinary chromium concentrations. 相似文献
24.
CB Verchere DA D'Alessio S Wang S Andrikopoulos SE Kahn 《Canadian Metallurgical Quarterly》1997,29(6):311-316
Islet amyloid polypeptide forms islet amyloid deposits in non-insulin-dependent diabetes mellitus. We have generated transgenic mice which express human islet amyloid polypeptide in their pancreatic beta cells yet do not develop islet amyloid deposits despite producing levels of the amyloidogenic human peptide 2 - 3 fold higher than the native (mouse) peptide. To determine whether marked overproduction of islet amyloid polypeptide is a potential cause of islet amyloid formation, we increased expression of this transgene by producing homozygous transgenic animals and by making heterozygous mice experimentally insulin resistant with nicotinic acid. Pancreatic content of islet amyloid polypeptide-like immunoreactivity in homozygous and nicotinic acid-treated mice was 2-fold (25 +/- 7 fmol/microg; n = 6) and 3.5-fold (47 +/- 20 fmol/microg; n = 3) higher, respectively, than that of untreated heterozygous animals (13+/-2 fmol/microg; n = 11; both p < 0.05). Despite this marked increase in production of islet amyloid polypeptide, neither group of mice developed gross islet amyloid deposits even after 16 months of age. We conclude that overproduction of islet amyloid polypeptide, even as produced by extreme insulin resistance, is not in itself sufficient for islet amyloid formation. 相似文献
25.
26.
The abrasion characteristics of Tencel fabrics were evaluated by Martindale abrasion and laundering, and the breakdown mechanism of fibers was surveyed by scanning electron microscopy. The fabric was subjected to pad‐dry‐cure treatment with two different types of modified dimethyloldihydroxyethylene urea resins (Reaktant DH and Reaktant FC). Although the degree of dry abrasion varied with different resins, the damage exhibited by individual fibers differed little from untreated to resin‐treated; the major mechanism of abrasion was through friction, and the mechanism of fiber failure was multiple splitting and transverse cracking. In untreated Tencel, the characteristic feature of wet abrasion was massive fibrillation, and in crosslinked fabrics, the wet abrasion mechanism was through fiber slippage and slicing action, although in the Reaktant FC‐treated fabric, the wet abrasion mechanism was more through slicing than through fiber splitting. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1391–1398, 2006 相似文献
27.
Integrating heterogeneous distributed COTS discrete-event simulation packages: an emerging standards-based approach 总被引:2,自引:0,他引:2
Taylor S.J.E. Xiaoguang Wang Turner S.J. Low M.Y.H. 《IEEE transactions on systems, man, and cybernetics. Part A, Systems and humans : a publication of the IEEE Systems, Man, and Cybernetics Society》2006,36(1):109-122
This paper reports on the progress made toward the emergence of standards to support the integration of heterogeneous discrete-event simulations (DESs) created in specialist support tools called commercial-off-the-shelf (COTS) discrete-event simulation packages (CSPs). The general standard for heterogeneous integration in this area has been developed from research in distributed simulation and is the IEEE 1516 standard The High Level Architecture (HLA). However, the specific needs of heterogeneous CSP integration require that the HLA is augmented by additional complementary standards. These are the suite of CSP interoperability (CSPI) standards being developed under the Simulation Interoperability Standards Organization (SISO-http://www.sisostds.org) by the CSPI Product Development Group (CSPI-PDG). The suite consists of several interoperability reference models (IRMs) that outline different integration needs of CSPI, interoperability frameworks (IFs) that define the HLA-based solution to each IRM, appropriate data exchange representations to specify the data exchanged in an IF, and benchmarks termed CSP emulators (CSPEs). This paper contributes to the development of the Type I IF that is intended to represent the HLA-based solution to the problem outlined by the Type I IRM (asynchronous entity passing) by developing the entity transfer specification (ETS) data exchange representation. The use of the ETS in an illustrative case study implemented using a prototype CSPE is shown. This case study also allows us to highlight the importance of event granularity and lookahead in the performance and development of the Type I IF, and to discuss possible methods to automate the capture of appropriate values of lookahead. 相似文献
28.
Using the Internet, “public” computing grids can be assembled using “volunteered” PCs. To achieve this, volunteers download and install a software application capable of sensing periods of low local processor activity. During such times, this program on the local PC downloads and processes a subset of the project's data. At the completion of processing, the results are uploaded to the project and the cycle repeats. 相似文献
29.
RM Bionta G Blewitt CB Bratton D Casper A Ciocio R Claus M Crouch ST Dye S Errede GW Foster W Gajewski KS Ganezer M Goldhaber TJ Haines TW Jones D Kielczewska WR Kropp JG Learned JM LoSecco J Matthews HS Park LR Price F Reines J Schulz S Seidel E Shumard D Sinclair HW Sobel JL Stone L Sulak R Svoboda G Thornton van der Velde JC C Wuest 《Canadian Metallurgical Quarterly》1987,36(1):30-36
30.
Makris Angela P.; Rush Craig R.; Frederich Robert C.; Taylor Alisia C.; Kelly Thomas H. 《Canadian Metallurgical Quarterly》2007,15(2):123
Modafinil is indicated for the management of excessive daytime sleepiness; however, recent studies have examined a broad range of potential uses. Given that clinical uses of modafinil may be expanding, this study compared modafinil and d-amphetamine effects on subjective and performance measures. Across 11 sessions, 11 healthy adults were tested after oral doses of placebo (5 sessions), modafinil (1.75 mg/kg, 3.50 mg/kg, or 7.00 mg/kg), and d-amphetamine (0.035 mg/kg, 0.070 mg/kg, 0.140 mg/kg) under double-blind, randomized conditions. Assessments of cognitive performance and subjective effects were completed before drug administration, 30 min after drug administration, and at hourly intervals after drug administration for 5 hr. Modafinil increased ratings on the Amphetamine and Morphine Benzedrine Group scales of the Addiction Research Center Inventory (ARCI) and increased ratings on the Vigor and Total Positive scales of the Profile of Mood States. d-Amphetamine increased visual analog ratings of feeling stimulated and liking the drug and increased ratings on the Morphine Benzedrine Group scale of the ARCI. Both medications significantly reduced visual analog scale ratings of feeling sleepy, and modafinil decreased ratings on the ARCI Pentobarbital-Chlorpromazine-Alcohol Group scale. Both medications sustained performance that deteriorated across time on the Sternberg Number Recognition Test. Modafinil also enhanced performance rate on the Digit-Symbol Substitution Task above baseline levels and increased response rate on the Repeated Acquisition of Response Sequences Task. These results suggest that modafinil engenders alerting effects and increases performance in healthy non-sleep-deprived individuals comparable with that of d-amphetamine. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献