全文获取类型
收费全文 | 1579篇 |
免费 | 2篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 24篇 |
金属工艺 | 7篇 |
机械仪表 | 8篇 |
建筑科学 | 3篇 |
矿业工程 | 3篇 |
轻工业 | 7篇 |
水利工程 | 20篇 |
石油天然气 | 21篇 |
无线电 | 66篇 |
一般工业技术 | 161篇 |
冶金工业 | 1214篇 |
原子能技术 | 44篇 |
自动化技术 | 2篇 |
出版年
2021年 | 6篇 |
2019年 | 11篇 |
2018年 | 23篇 |
2017年 | 6篇 |
2016年 | 18篇 |
2015年 | 11篇 |
2014年 | 13篇 |
2013年 | 11篇 |
2012年 | 19篇 |
2011年 | 18篇 |
2010年 | 17篇 |
2009年 | 7篇 |
2008年 | 17篇 |
2007年 | 5篇 |
2006年 | 8篇 |
2005年 | 8篇 |
2004年 | 7篇 |
2002年 | 4篇 |
2001年 | 5篇 |
1999年 | 39篇 |
1998年 | 329篇 |
1997年 | 229篇 |
1996年 | 156篇 |
1995年 | 106篇 |
1994年 | 62篇 |
1993年 | 74篇 |
1992年 | 10篇 |
1991年 | 24篇 |
1990年 | 10篇 |
1989年 | 8篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 8篇 |
1981年 | 13篇 |
1980年 | 16篇 |
1979年 | 5篇 |
1978年 | 18篇 |
1977年 | 54篇 |
1976年 | 100篇 |
1975年 | 6篇 |
1974年 | 7篇 |
1973年 | 7篇 |
1972年 | 6篇 |
1970年 | 6篇 |
1967年 | 4篇 |
1957年 | 7篇 |
排序方式: 共有1582条查询结果,搜索用时 625 毫秒
61.
The aim of the study was TPS diagnostic value determination in the serum of women with breast cancer as compared with MCA and CA 15-3. The relationship between the serum concentration of these antigens and patient age, clinical stage, histological grade, presence of metastases to lymph nodes and histological type of neoplasm was evaluated. Studies were conducted on the sera of 139 women before surgical procedure aged 28-81, treated in the Clinic of Oncology, at Karol Marcinkowski University of Medical Sciences in Poznań. The TPS concentration was determined using the "BEKI Diagnostics" immunoenzymatic method, MCA - by the "Roche" test and CA 15-3 concentration was determined by the "Abbott" immunofluorescent test. The study showed significantly higher levels of TPS, CA 15-3 and MCA in women with cancer, compared with values in healthy women and women with mastopathy. The highest median of concentration and frequency of occurrence was obtained for TPS. A correlation between enhancement of TPS and CA 15-3 concentration with clinical stage was observed. A similar connection was noted in women with metastases to the lymph nodes. Serum MCA concentration results did not demonstrate the above effects. The study suggests, that in estimating the clinical condition of women with breast cancer, the simultaneous determination of TPS with CA 15-3 seems to be a more useful prognostic factor than TPS or CA 15-3 with MCA. 相似文献
62.
Personal clinical observations during the recent years allow the authors to confirm the indisputable value of surgical experience got during the Great Patriotic War (1941-1945) and in particular, the "fourfold" scheme proposed by V. I. Voiachek for the diagnosis and treatment of blind gunshot wounds to the skull base. Computed tomography considerably increases the probability of detection of the exact localization of foreign bodies in complex anatomical structures of the skull and thus facilitates choosing the most rational surgical management. The use of the electro-optical transducer for the extraction of foreign bodies from almost inaccessible areas of the skull base decreases the risk of operation. 相似文献
63.
During a six-month period 2,221 haemocultures obtained from patients hospitalized in the Faculty Hospital Olomouc were examined. In all 304 isolated bacteria the sensitivity was assessed by the standard dilution micromethod and moreover all positive haemocultures were examined the "direct" disc method. Agreement between the results of the two methods was proved in 84% of pairs of tests and within a range from 67 to 100%, depending on the type of antimicrobial preparation. Based on these findings it may be stated that assessment of the sensitivity by the "direct" method agrees significantly with assessment of the sensitivity according to minimal inhibitory concentrations (MIC). In patients with septicaemia this procedure makes it possible to change empirical antibiotherapy by 24 hours sooner to aimed therapy. 相似文献
64.
SM Riordan CJ McIver BM Walker VM Duncombe TD Bolin MC Thomas 《Canadian Metallurgical Quarterly》1996,91(9):1795-1803
OBJECTIVES: To i) document the sensitivity and specificity of a combined scintigraphic/lactulose breath hydrogen test for small intestinal bacterial overgrowth and ii) investigate the validity of currently accepted definitions of an abnormal lactulose breath hydrogen test based on "double peaks" in breath hydrogen concentrations. METHODS: Twenty-eight subjects were investigated with culture of proximal small intestinal aspirate and a 10-g lactulose breath hydrogen test combined with scintigraphy. Gastroduodenal pH, the presence or absence of gastric bacterial overgrowth, and the in vitro capability of overgrowth flora to ferment lactulose were determined. RESULTS: Sensitivity (16.7%) and specificity (70.0%) of the lactulose breath hydrogen test alone for small intestinal bacterial overgrowth were poor. Combination with scintigraphy resulted in 100% specificity, because double peaks in serial breath hydrogen concentrations may occur as a result of lactulose fermentation by cecal bacteria. Sensitivity increased to 38.9% with scintigraphy, because a single rise in breath hydrogen concentrations, commencing before the test meal reaches the cecum, may occur in this disorder. Sensitivity remained suboptimal irrespective of the definition of small intestinal bacterial overgrowth used, the nature of the overgrowth flora, favorable luminal pH, the presence of concurrent gastric bacterial overgrowth, or the in vitro ability of the overgrowth flora to ferment lactulose. CONCLUSIONS: Definitions of an abnormal lactulose breath hydrogen test based on the occurrence of double peaks in breath hydrogen concentrations are inappropriate. Not even the addition of scintigraphy renders this test a clinically useful alternative to culture of aspirate for diagnosing small intestinal bacterial overgrowth. 相似文献
65.
JR Bearder VM Frydman P Gaskin IK Hatton WE Harvey J McMillan BO Phinney 《Canadian Metallurgical Quarterly》1976,39(2):178-183
Angiotensin II (A II) and analogues were tested for their ability to restore electrical and mechanical activity to cardiac muscle preparations in which the fast Na+ channels had been inactivated by partial depolarization (22-27 mM K+) or by tetrodotoxin (TTX). The partially depolarized or TTX-blocked preparations were chosen because under these conditions electrical and mechanical responses are primarily Ca2+ -dependent. In depolarized rabbit right atria, A II restored spontaneous mechanical and electrical activity (measured by both intracellular and extracellular recording techniques). The frequency of action potential discharge was concentration-dependent; the threshold concentration of A II was 10(-10) M, the ED50 was 8 X 10(-9) M, and the maximum effect was observed at 5 X 10(-8) M. In contrast, depolarized guinea pig atria were insensitive to A II, Sar1-angiotensin II, and des-Asp1-angiotensin II, even at concentrations as high as 10(-5) M. Rabbit papillary muscle (TTX-blocked), embryonic (18-day) chick heart (partially depolarized) and chick heart reaggregates (TTX-blocked) responded similarly to rabbit atria in that A II (9.6 X 10(-7) M) restored both electrical and mechanical activity. We found that in these preparations the action of A II was unaffected by propranolol (5.0 X 10(-6) M to 5.0 X 10(-5) M) but was blocked by Mn2+ (10(-3) M), D-600 (1 X 10(-7) g/ml) and the specific A II antagonists Sar1-Ala8-angiotensin II (P-113) (5.0 X 10(-5) M) and Sar1-Ile8-angiotensin II (5.28 X 10(-5) M). We conclude that the positive inotropic effect of A II on the myocardium is due to its ability to increase transmembrane ion movements in or through the cell membrane. The ability of Mn2+ and D-600 to block this effect suggests that this ion movement is via the so-called "slow channels." 相似文献
66.
S. V. Bobashev N. P. Mende V. A. Sakharov D. M. Van Wie 《Technical Physics Letters》2004,30(8):635-637
Magnetohydrodynamic impact on a cold supersonic nitrogen flow with external magnetic field was realized in an experimental
complex based on the Big Shock Tube at the Ioffe Physicotechnical Institute. A pulsed supersonic flow with a Mach number of
M=4 and steady phase duration of about 1.5 ms was created by expansion of the shock-heated nitrogen flow from a supersonic
nozzle. The gas was ionized by pulsed discharge between two electrodes mounted on the nozzle wall so that an electric current
of up to ∼500 A passed in the direction perpendicular to the gas flow at the dielectric wall. External magnetic field ∼0.3
T was perpendicular to the gas flow and the current direction. It is established that the magnetic field significantly modifies
the shock wave structure in the flow. 相似文献
67.
68.
69.
70.
V. N. Chuvil’deev A. V. Nokhrin I. M. Makarov Yu. G. Lopatin N. V. Sakharov N. V. Melekhin A. V. Piskunov E. S. Smirnova V. I. Kopylov 《Russian Metallurgy (Metally)》2012,2012(5):415-427
The structure and the electrical and mechanical properties of Al-Mg-0.22 wt % Sc-0.15 wt % Zr alloys with various magnesium contents (0, 1.5, 4.5 wt %) are experimentally studied during the decomposition of the solid solution of scandium and zirconium in the states after solidification from a melt (cast ingots) and after subsequent multicycle equal-channel angular pressing (microcrystalline structure). The dependences of electrical resistivity ??, microhardness HV, macroelasticity limit ??0, and yield strength ??y on the annealing temperature and time are analyzed. 相似文献