全文获取类型
收费全文 | 7622篇 |
免费 | 562篇 |
国内免费 | 220篇 |
专业分类
电工技术 | 436篇 |
技术理论 | 1篇 |
综合类 | 496篇 |
化学工业 | 1291篇 |
金属工艺 | 304篇 |
机械仪表 | 402篇 |
建筑科学 | 493篇 |
矿业工程 | 209篇 |
能源动力 | 208篇 |
轻工业 | 711篇 |
水利工程 | 130篇 |
石油天然气 | 470篇 |
武器工业 | 52篇 |
无线电 | 671篇 |
一般工业技术 | 907篇 |
冶金工业 | 635篇 |
原子能技术 | 53篇 |
自动化技术 | 935篇 |
出版年
2024年 | 28篇 |
2023年 | 114篇 |
2022年 | 193篇 |
2021年 | 282篇 |
2020年 | 200篇 |
2019年 | 183篇 |
2018年 | 231篇 |
2017年 | 249篇 |
2016年 | 226篇 |
2015年 | 271篇 |
2014年 | 378篇 |
2013年 | 483篇 |
2012年 | 485篇 |
2011年 | 527篇 |
2010年 | 434篇 |
2009年 | 404篇 |
2008年 | 420篇 |
2007年 | 392篇 |
2006年 | 406篇 |
2005年 | 303篇 |
2004年 | 227篇 |
2003年 | 207篇 |
2002年 | 184篇 |
2001年 | 201篇 |
2000年 | 165篇 |
1999年 | 182篇 |
1998年 | 253篇 |
1997年 | 178篇 |
1996年 | 125篇 |
1995年 | 104篇 |
1994年 | 87篇 |
1993年 | 62篇 |
1992年 | 35篇 |
1991年 | 26篇 |
1990年 | 21篇 |
1989年 | 20篇 |
1988年 | 21篇 |
1987年 | 12篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 5篇 |
1983年 | 10篇 |
1982年 | 10篇 |
1980年 | 3篇 |
1979年 | 5篇 |
1978年 | 3篇 |
1977年 | 10篇 |
1976年 | 11篇 |
1975年 | 2篇 |
1974年 | 3篇 |
排序方式: 共有8404条查询结果,搜索用时 15 毫秒
991.
M Kogan S Rojas P Gómez F Suárez J F Mu?oz C Alister 《Water science and technology》2007,56(2):169-178
A field study was performed to evaluate the accuracy of six pesticide screening leaching indexes for herbicide movement. Adsorption, dissipation and soil movement were studied in a vineyard in a sandy loam soil during 2005 season. Simazine, diuron, pendimethalin, oxyfluorfen and flumioxazin were applied to bare soil at rates commonly used, and their soil concentrations throughout soil profile were determined at 0, 10, 20, 40 and 90 days after application (DAA). Herbicides were subjected to two pluviometric regimens, natural field condition and modified conditions (plus natural rainfall 180 mm). Leaching indexes utilized were: Briggs's Rf, Hamaker's Rf, LEACH, LPI, GUS and LIX. Simazine reached 120 cm, diuron 90 cm, flumioxazin 30 cm soil depth respectively. Pendimethalin and oxyfluorfen were retained up to 5 cm. None of the herbicides leaching was affected by rainfall regimen. Only flumioxazin field dissipation was clearly affected by pluviometric condition. The best representation of the herbicide soil depth movement and leaching below 15 cm soil depth were: Hamaker's Rf < Briggs's Rf < GUS < LPI, < LEACH < LIX. Field results showed a good correlation between herbicides K(d) and their soil depth movement and mass leached below 15 cm soil depth. 相似文献
992.
Formestane is a new aromatase inhibitor used as second-line endocrine treatment for postmenopausal women with advanced breast cancer. The most frequent side effects are local reactions. Here we report the development of immune thrombocytopenia coinciding with administration of this drug. 相似文献
993.
994.
D. Zavrtanik F. Sever M. Pleško M. Mušič G. Kernel N.W. Tanner E.G. Michaelis A. Stanovnik 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1984,227(2):237-241
A long liquid Cherenkov counter has been used to measure the proportion of muons in positive and negative pion beams in the momentum range between 300 and 460 MeV/c. A nine-parameter function fits all the spectra well. The data show a smooth dependence on incident momenta and agree with calculations of pion and muon pulse heights. 相似文献
995.
The spectral response of p-n silicon solar cells is calculated as a generalisation of results for monochromatic light illumination. The total short-circuit current is calculated from the spectral response and used for I(V)plottings. 相似文献
996.
Mu?oz Ricardo F.; Hollon Steven D.; McGrath Ellen; Rehm Lynn P.; VandenBos Gary R. 《Canadian Metallurgical Quarterly》1994,49(1):42
The majority of cases of clinical depression go unrecognized and untreated, despite the fact that depression is an eminently treatable disorder. The Agency for Health Care Policy and Research (AHCPR) recently published a set of clinical practice guidelines focused on depression in primary care settings. The review of the literature on which the guidelines are based is thorough and appropriate and should enhance the detection of depression and the quality of pharmacotherapy for depression. However, the guidelines encourage primary care physicians to provide pharmacotherapy to their depressed patients as the 1st line of treatment. The wisdom of this recommendation is questioned and revisions to the guidelines are suggested. Specifically, patients should be informed of the broad array of treatment options available and provided with a more balanced presentation of the potential benefits of psychotherapy for depression. Patients should decide which treatment alternative they wish to undergo. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
997.
The inhibitory effects on HIV replication of megalomicin (MGM, an inhibitor of intra-Golgi vesicle transport, have been studied. In experiments at low multiplicity of infection on Jurkat and MT2 cell lines. MGM inhibited the production of p24 antigen, the formation of syncytia, and the induction of apoptosis at concentrations below 5 microM. Furthermore, PCR analysis of genomic DNA showed that, in the presence of MGM, HIV-1 had been eradicated from the culture. MGM also inhibited replication of primary isolates of HIV-1 in blood lymphoblasts and more importantly, at 1 microM, MGM inhibited depletion of CD4+ T cells in cultures of blood lymphocytes from seropositive patients. Finally, MGM inhibited the generation of infectious virions and the processing of the envelope protein precursor gp160 to its mature forms, resulting in the rapid degradation of gp 160. These data suggest that MGM induces a powerful inhibitory effect on HIV-1 replication at nontoxic concentrations by preventing the processing of HIV-1 gp160 envelope protein and the subsequent formation of infectious viral particles. 相似文献
998.
999.
R Lagos P Herrera A Sepúlveda A Mu?oz C Benavente I Bravo T Lamberg 《Canadian Metallurgical Quarterly》1996,124(10):1211-1218
BACKGROUND: Urinary tract infections in children are associated with functional and anatomical abnormalities of the urinary tract, they tend to recur and can cause permanent kidney damage. AIM: To study in children with urinary tract infections, microbiological factors associated to recurrence, functional and anatomical abnormalities of the urinary tract. PATIENTS AND METHODS: A prospective sample of children was incorporated into a follow-up protocol after their first episode of bacteriologically-demonstrated urinary tract infection. In all patients an abdominal ultrasound examination and a mictional urethrocystography were done and the presence of fimbriae was studied in isolated strains of Escherichia coli. RESULTS: Two hundred fifteen cases bad an adequate adherence to the study protocol, 190 caused by E coli. Fimbriated E coli strains were isolated with greater frequency from children with pyelonephritis than from those with a low urinary tract infection (50 and 28% respectively). The absence of fimbriae in E coli strains was associated with a higher risk of recurrent infections (odds ratio = 3, confidence intervals = 2-9.2) and an abnormal urethrocystography (odds ratio = 3, confidence intervals = 1.1-10.2). CONCLUSIONS: These data are consistent with foreign reports and support the need to study adhesins in E coli strains isolated from children with urinary tract infections. 相似文献
1000.
A Santamaría F Moya C Martinez R Martino J Martinez-Pérez E Mu?iz-Díaz 《Canadian Metallurgical Quarterly》1998,83(10):951-952
Transfusion-related acute lung injury (TRALI) is an infrequent complication of hemotherapy. Antigranulocyte antibodies, most of them present in donor's serum, have been implicated in its pathogenesis. We describe a case of TRALI, following red blood cell transfusion, associated with an antigranulocyte antibody with NA1 specificity in the patient's serum. 相似文献