全文获取类型
收费全文 | 4758篇 |
免费 | 48篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 40篇 |
综合类 | 1篇 |
化学工业 | 390篇 |
金属工艺 | 53篇 |
机械仪表 | 47篇 |
建筑科学 | 89篇 |
矿业工程 | 7篇 |
能源动力 | 39篇 |
轻工业 | 330篇 |
水利工程 | 18篇 |
石油天然气 | 7篇 |
无线电 | 212篇 |
一般工业技术 | 366篇 |
冶金工业 | 2791篇 |
原子能技术 | 17篇 |
自动化技术 | 403篇 |
出版年
2024年 | 13篇 |
2022年 | 19篇 |
2021年 | 34篇 |
2020年 | 37篇 |
2019年 | 40篇 |
2018年 | 40篇 |
2017年 | 36篇 |
2016年 | 35篇 |
2015年 | 32篇 |
2014年 | 48篇 |
2013年 | 123篇 |
2012年 | 80篇 |
2011年 | 111篇 |
2010年 | 88篇 |
2009年 | 78篇 |
2008年 | 102篇 |
2007年 | 110篇 |
2006年 | 94篇 |
2005年 | 67篇 |
2004年 | 69篇 |
2003年 | 70篇 |
2002年 | 68篇 |
2001年 | 45篇 |
2000年 | 55篇 |
1999年 | 141篇 |
1998年 | 849篇 |
1997年 | 499篇 |
1996年 | 314篇 |
1995年 | 184篇 |
1994年 | 137篇 |
1993年 | 197篇 |
1992年 | 49篇 |
1991年 | 40篇 |
1990年 | 42篇 |
1989年 | 54篇 |
1988年 | 38篇 |
1987年 | 38篇 |
1986年 | 37篇 |
1985年 | 45篇 |
1984年 | 26篇 |
1983年 | 34篇 |
1982年 | 46篇 |
1981年 | 40篇 |
1980年 | 52篇 |
1979年 | 25篇 |
1978年 | 25篇 |
1977年 | 51篇 |
1976年 | 119篇 |
1975年 | 26篇 |
1963年 | 13篇 |
排序方式: 共有4810条查询结果,搜索用时 15 毫秒
971.
972.
973.
MP García-Hernández A García-Ayala MT Elbal B Agulleiro 《Canadian Metallurgical Quarterly》1996,28(5):577-585
The adenohypophysis (ADH) of the Mediterranean yellowtail was studied using the peroxidase-antiperoxidase technique. Human corticotropin (ACTH) (1-24)-immunoreactive (ir) cells were found bordering the neurohypophysis (NH) and salmon prolactin (PRL)-ir cells were arranged in thick cords, both in the rostral pars distalis (RPD). Gonadotropin (GTH)-, thyrotropin (TSH)- and growth hormone (GH)-ir cells were observed in the proximal pars distalis (PPD). Anti-chum salmon GTH I and anti-chum salmon GTH II immunostained the same cells in the outermost part of the ADH at the level of the PPD and the PI. In addition to these cells, some cells grouped in the inner areas of the posterior PPD were revealed by catfish alpha, beta-GTH antiserum. Human beta-TSH-ir cells formed small groups and discontinuous strands in the PPD often in contact with the NH. Tilapia GH-ir cells formed cords mainly surrounding the NH in the central PPD, while cod somatolactin- and alpha MSH-ir cells mainly surrounded the NH branches in the PI. 相似文献
974.
975.
976.
CN Bialik B Wolf EL Rachofsky JB Ross WR Laws 《Canadian Metallurgical Quarterly》1998,75(5):2564-2573
Many biological systems have multiple fluorophores that experience multiple depolarizing motions, requiring multiple lifetimes and correlation times to define the fluorescence intensity and anisotropy decays, respectively. To simplify analyses, an assumption often made is that all fluorophores experience all depolarizing motions. However, this assumption usually is invalid, because each lifetime is not necessarily associated with each correlation time. To help establish the correct associations and recover accurate kinetic parameters, a general kinetic scheme that can examine all possible associations is presented. Using synthetic data sets, the ability of the scheme to discriminate among all nine association models possible for two lifetimes and two correlation times has been evaluated. Correct determination of the association model, and accurate recovery of the decay parameters, required the global analysis of related data sets. This general kinetic scheme was then used for global analyses of liver alcohol dehydrogenase anisotropy data sets. The results indicate that only one of the two tryptophan residues in each subunit is depolarized by process(es) independent of the enzyme's rotations. By applying the proper kinetic scheme and appropriate analysis procedures to time-resolved fluorescence anisotropy data, it is therefore possible to examine the dynamics of specific portions of a macromolecule in solution. 相似文献
977.
E Cubo MT Andrés A Rojo A Guerrero DG Urra R Méndez 《Canadian Metallurgical Quarterly》1998,26(153):774-776
INTRODUCTION: Sustained hypoglycemia causes serious cerebral damage. The cortex, hippocampus and basal ganglia are particularly vulnerable to this. Exceptionally, there have been communications regarding neuroimaging visualization of cerebral lesions attributable to hypoglycemia only. We present the case of a woman who suffered hypoglycemic coma with permanent neurological damage. Lesions were seen on magnetic resonance (MR) and cranial computerized tomography (CT). CLINICAL CASE: A 22 year old woman with no vascular risk factors was admitted to hospital in hypoglycemic coma, after attempting suicide with oral antidiabetic drugs. The duration of the coma was unknown. On admission the glycaemia was 28 mg/dl. Cranial CT scan was normal during the first 24 hours. Cerebral MR scan one week late showed hyperintense lesions in T2, basal ganglia and left hippocampus. The cranial CT scan one year later showed diffuse atrophy, with bilateral lesions of low attenuation in the basal ganglia and dilatation of the ventricular system. CONCLUSIONS: It is unusual to see lesions secondary to hypoglycemia on neuroimaging investigations. The etiopathogenic mechanism is still unknown and it has generally been described in diabetic patients. In our case these lesions can only be attributed to hypoglycemia. MR is more sensitive than cranial CT scan for the detection of these lesions during the acute phase. 相似文献
978.
BG Bylsma S Abachi P Baringer De Bonte R D Koltick FJ Loeffler EH Low RL McIlwain DH Miller CR Ng LK Rangan EI Shibata M Derrick KK Gan P Kooijman JS Loos B Musgrave LE Price J Repond K Sugano D Blockus B Brabson J Brom C Jung H Ogren HW Paik DR Rust C Akerlof J Chapman D Errede MT Ken DI Meyer D Nitz R Thun R Tschirhart B Cork 《Canadian Metallurgical Quarterly》1987,35(7):2269-2271
979.
980.
The Monadic Phases Coding System (MP) and the Maximally Discriminative Facial Movement Coding System (MAX) are both widely used to define and quantify categories of infant affective behavior. To evaluate the validity of extrapolating research findings from one system to another, we used both systems to code videotapes of 12 four-month-old infants engaged in mother–infant interaction. Interobserver agreement was higher with MP; interobserver reliability was equivalent. Point estimates for the percentages of negative and positive, but not interest, expressions were equivalent. MP and MAX generally agreed about the type of expression presented. Intersystem correlations supported the concurrent, but not discriminant, validity of MP and MAX categories. Interest expressions were not orthogonal to negative and positive affect. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献