全文获取类型
收费全文 | 4146篇 |
免费 | 242篇 |
国内免费 | 4篇 |
专业分类
电工技术 | 61篇 |
综合类 | 1篇 |
化学工业 | 985篇 |
金属工艺 | 141篇 |
机械仪表 | 82篇 |
建筑科学 | 90篇 |
矿业工程 | 14篇 |
能源动力 | 150篇 |
轻工业 | 504篇 |
水利工程 | 13篇 |
石油天然气 | 11篇 |
无线电 | 107篇 |
一般工业技术 | 691篇 |
冶金工业 | 1066篇 |
原子能技术 | 26篇 |
自动化技术 | 450篇 |
出版年
2023年 | 29篇 |
2022年 | 79篇 |
2021年 | 126篇 |
2020年 | 98篇 |
2019年 | 85篇 |
2018年 | 168篇 |
2017年 | 160篇 |
2016年 | 176篇 |
2015年 | 137篇 |
2014年 | 168篇 |
2013年 | 281篇 |
2012年 | 199篇 |
2011年 | 243篇 |
2010年 | 168篇 |
2009年 | 142篇 |
2008年 | 128篇 |
2007年 | 134篇 |
2006年 | 87篇 |
2005年 | 63篇 |
2004年 | 61篇 |
2003年 | 53篇 |
2002年 | 53篇 |
2001年 | 28篇 |
2000年 | 19篇 |
1999年 | 21篇 |
1998年 | 176篇 |
1997年 | 198篇 |
1996年 | 137篇 |
1995年 | 90篇 |
1994年 | 47篇 |
1993年 | 64篇 |
1992年 | 18篇 |
1991年 | 9篇 |
1990年 | 19篇 |
1989年 | 14篇 |
1988年 | 14篇 |
1987年 | 11篇 |
1986年 | 10篇 |
1985年 | 15篇 |
1984年 | 32篇 |
1983年 | 19篇 |
1982年 | 39篇 |
1981年 | 45篇 |
1980年 | 55篇 |
1979年 | 27篇 |
1978年 | 37篇 |
1977年 | 110篇 |
1976年 | 234篇 |
1975年 | 13篇 |
1973年 | 12篇 |
排序方式: 共有4392条查询结果,搜索用时 23 毫秒
31.
The coincidence of neuronal stress induced by intoxication and an overexpression of amyloid precursor protein (APP) in the brains of children was examined. Brains of ten children accidentally intoxicated by poisonous mushroom were studied by means of immunohistochemical methods using monoclonal antibodies generated against different domains of APP and glial cell markers. Overexpression of APP was found in the brain neurons of all intoxicated children. Neurons were immunopositive with the antibodies generated against the middle (amyloid beta protein) domain of APP. No extracellular deposits were found in the tissue. Our results provided, for the first time, the evidence that overexpression of APP concomitant with the neuronal stress is age-independent phenomenon appearing not only in the brain of adults but in very young individuals as well. 相似文献
32.
MG Niemia?towski FN Toka E Malicka Gieryńska I Spohr de Faundez A Schollenberger 《Canadian Metallurgical Quarterly》1996,44(5-6):373-378
An 11-year global WHO campaign for eradication of smallpox finished in October 1977 as the result of Edward Jenner's primary success in 1796, who for the first time applied human vaccination against variola virus (VARV). The 200th anniversary of this happening is a good occasion to summarize the current status of the knowledge about the role of B and T lymphocytes in the control of orthopoxvirus infections. This short review concentrates on general characteristics of orthopoxviruses and the immune response to infection, mainly by vaccinia virus (VV) and ectromelia virus (EV). 相似文献
33.
J G?uszek B Raszeja-Wanic I Stachowiak F Banaszak L Szcze?niak D Musialik T Kosicka A Tykarski A Boruczkowska A Sko?uda A Ma?aczyńska A Wichrowska K Rutz-Danielczak B Krasińska 《Canadian Metallurgical Quarterly》1996,96(6):570-576
Two groups of hypertensive patients: 137 responsive (on one or two drugs) and 162 resistant on antihypertensive treatment in the similar age were compared. Resistant patients (on three or more drugs) characterize by significantly higher body weight and BMI, longer history of hypertension, more frequent hypertension prevalance in family members and lower education. Level of triglycerides in resistant on antihypertensive treatment patients was significantly higher than in responsive patients. Insulin level in blood in 31 patients with essential hypertension was significantly higher than in 36 healthy persons and 20 patients with renovascular hypertension and resistant on antihypertensive therapy. In 14 patients with essential hypertension resistant to treatment insulin level one hour after oral glucose load was significantly (p < 0.01) higher than in 16 patients with essential hypertension responsive to antihypertensive treatment. 相似文献
34.
35.
Anna Michalska Alicja Ceglińska Henryk Zieliński 《European Food Research and Technology》2007,225(3-4):545-551
Rye flours with extraction rate of 100% (wholemeal flour), 95% (brown flour), 90% (brown flour) and 70% (light flour) were
prepared in order to study the relation between flour extraction rates and content of bioactive compounds. The following compounds
were analysed: total phenolic compounds (TPC), total flavonoids (TF), inositol hexaphosphate (IP6), reduced (GSH) and oxidized
(GSSG) glutathione, tocopherols (T) and tocotrienols (T3). The reduced/oxidized glutathione status (GSH/GSSG) of the flours
was examined as a potential index of flour resistance against oxidative stress. The following observations were made in relation
to the flour extraction rates and bioactive compounds contents: (a) milling process caused decrease in content in TPC, TF,
IP6, GSH and GSSG, T and T3, (b) the most resistant against oxidation processes were suggested a brown flours, then light
and finally wholemeal flour, (c) the ratio of tocotrienols to tocopherols (T3/T) was the highest in rye flours with extraction
rate of 100–90% whereas light flour was the poorest source of tocopherols and tocotrienols. The provided data support current
trend to increase number of rye products from wholemeal or brown flours. 相似文献
36.
37.
Generalized adaptive notch filters with frequency debiasing for tracking of polynomial phase systems
Generalized adaptive notch filters are used for identification/tracking of quasi-periodically varying dynamic systems and can be considered an extension, to the system case, of classical adaptive notch filters. For general patterns of frequency variation the generalized adaptive notch filtering algorithms yield biased frequency estimates. We show that when system frequencies change slowly in a smooth way, the estimation bias can be substantially reduced by means of post-filtering of the frequency estimates. The modified (debiased) algorithm has better tracking capabilities than the original algorithm. 相似文献
38.
39.
A grid (or a mesh) is a two-dimensional permutation: an m× n-grid of size mn is an m× n-matrix where the entries run through the elements {1,2, …, mn}. We prove that if δ1 and δ2 are any two linear orders on {1,2, …, N}, then they can be simultaneously embedded (in a well defined sense) into a unique grid having the smallest size. 相似文献
40.
E Szczepańska-Sadowska P Paczwa S Loń D Ganten 《Canadian Metallurgical Quarterly》1998,16(10):1505-1514
OBJECTIVE: Renin transgenic hypertensive rats [TGR(mRen2)27] have increased contents of angiotensin II and arginine vasopressin (AVP) in the cardiovascular brain regions. The aim of the present study was to evaluate the effects of centrally released AVP on the regulation of baseline blood pressure in TGR(mRen2)27 rats and to determine the interaction between AVP and angiotensin II in the central control of blood pressure in this model of hypertension. DESIGN: Three basic series of experiments were performed on 20 TGR(mRen2)27 and 20 Hannover Sprague-Dawley conscious rats, chronically instrumented with lateral cerebral ventricle (LCV) cannulae and femoral artery catheters. In series 1, blood pressure and heart rate were recorded during an LCV infusion of artificial cerebrospinal fluid before and after LCV administration of angiotensin II. In series 2, the effects of an LCV administration of angiotensin 11 (100 ng) on mean arterial pressure and the heart rate were determined during LCV infusion of a selective AVP receptor (V1) antagonist [1-(1-mercapto-4-methylcyclohexaneacetic acid)-8-arginine vasopressin (MeCAAVP) and d(CH2)5[Tyr(Me)2,Ala-NH2(9)]AVP] or a selective angiotensin II type 1 (AT1) receptor antagonist (losartan) or both. In series 3, mean arterial pressure and the heart rate were determined after an LCV injection of either AVP (10 ng) or AVP together with angiotensin II. RESULTS: The LCV infusions of antagonists to V1 and AT1 receptors caused significant comparable decreases in baseline MAP in TGR(mRen2)27 but not in Sprague-Dawley rats. Angiotensin II elicited significant pressor responses, both in TGR(mRen2)27 and in Sprague-Dawley rats. Blockade of V1 receptors significantly reduced the duration and the maximum amplitude of the central pressor response to angiotensin II in TGR(mRen2)27 rats, whereas in Sprague-Dawley rats the maximum pressor effect was not significantly altered. In both strains, the pressor response to angiotensin II was abolished by blockade of AT1 receptors. CONCLUSIONS: The results indicate that the elevated blood pressure in TGR(mRen2)27 rats is partly caused by increased function of the brain angiotensinergic AT1 and vasopressinergic V1 systems. Centrally released AVP is involved in mediation of the pressor effect exerted by centrally applied angiotensin II in TGR(mRen2)27 rats. 相似文献