全文获取类型
收费全文 | 6706篇 |
免费 | 5篇 |
专业分类
电工技术 | 6篇 |
化学工业 | 66篇 |
金属工艺 | 8篇 |
机械仪表 | 4篇 |
建筑科学 | 10篇 |
能源动力 | 13篇 |
轻工业 | 48篇 |
石油天然气 | 3篇 |
无线电 | 36篇 |
一般工业技术 | 46篇 |
冶金工业 | 6412篇 |
原子能技术 | 4篇 |
自动化技术 | 55篇 |
出版年
2022年 | 5篇 |
2017年 | 3篇 |
2016年 | 2篇 |
2015年 | 5篇 |
2014年 | 8篇 |
2013年 | 10篇 |
2012年 | 9篇 |
2011年 | 8篇 |
2010年 | 14篇 |
2009年 | 15篇 |
2008年 | 8篇 |
2007年 | 10篇 |
2006年 | 13篇 |
2005年 | 23篇 |
2004年 | 14篇 |
2003年 | 13篇 |
2002年 | 7篇 |
2001年 | 9篇 |
2000年 | 5篇 |
1999年 | 191篇 |
1998年 | 2056篇 |
1997年 | 1145篇 |
1996年 | 732篇 |
1995年 | 377篇 |
1994年 | 329篇 |
1993年 | 391篇 |
1992年 | 43篇 |
1991年 | 93篇 |
1990年 | 69篇 |
1989年 | 81篇 |
1988年 | 79篇 |
1987年 | 85篇 |
1986年 | 75篇 |
1985年 | 71篇 |
1984年 | 4篇 |
1983年 | 12篇 |
1982年 | 34篇 |
1981年 | 44篇 |
1980年 | 40篇 |
1979年 | 7篇 |
1978年 | 22篇 |
1977年 | 163篇 |
1976年 | 325篇 |
1975年 | 16篇 |
1955年 | 7篇 |
1943年 | 3篇 |
1941年 | 3篇 |
1940年 | 8篇 |
1939年 | 3篇 |
1938年 | 5篇 |
排序方式: 共有6711条查询结果,搜索用时 437 毫秒
31.
32.
33.
AL Benabid JC Persat JF Piquard M Barge JP Chirossel 《Canadian Metallurgical Quarterly》1976,34(1-4):287-294
The authors present a four electrode rheographic technique for simiquantitative continuous measurement of CBV, by examining changes in cerebral tissue impedance induced by changes in blood content of the brain parenchyma. Correlation between the data obtained and ICP measurements permits conclusions regarding the behaviour of the cerebral blood bed. pCO2 regulates CBV, and the phenomenon is reversible according to a hystereris shaped time course in acute experiments. The rebound of ICP after sudden injections of CSF into the cisterna magna is of a vasogenic nature. Changes in CSF volume induce contrary changes in CBV. Pharmacological effects can be studied. The validity of the method is discussed. 相似文献
34.
JL Beaumont V Beaumont F Jan JC Buxtorf 《Canadian Metallurgical Quarterly》1976,98(44):7057-8, 7061-4, 7067-8
In this review, the clinical reality, the statistical risk, and the frequency of thromboembolism in pill users are evaluated, 6 cases described, and premonitory signs, treatment, and etiology are discussed. Clinically these thromboembolisms appear in unlikely subjects and unusual bodily locations such as the mesenteric veins, without warning. The risks are 8-11 times higher for pulmonary thrombosis, 3-6 times higher for myocardial infarction, based on previously used higher dosed pills. The frequency is about .5-1/1000, or 500-1000/year in France. Some of the cases described used pills with less than .05 mg estrogen, some were heavy smokers, 1 woman died, 1 had a lower extremity amputation, and 1 woman had demonstrated IgG lamda antibodies against ethinyl estradiol. Premonitory signs are rare, and unsually ignored. The immediate action is to stop the pill and start anticoagulants. The cause of these disorders is not known in detail, but is presumed to be estrogens, therefore, low-dose pills, i.e., those with .05 or .03 mg ethinyl estradiol, should be used if possible. Other risk factors are surgery, age, immobilization, history of vein disorders, smoking, hyperlipidemia, hypertension, especially since the pill potentiates hypertension, hyperlipidemia, and hypercoagulation. Some mechanisms proposed are hyperlipidemia, disturbed blood coagulation factors, decreased fibrinolysis, alterations in the blood vessel endothelium and immunity against the estrogen in the pill. 相似文献
35.
36.
JC Allen 《Canadian Metallurgical Quarterly》1976,82(2):316-317
Fifth patients had bilateral intracapsular cataract extractions with a peripheral iridectomy in one eye and a sector iridectomy in the opposite eye. There was no difference in photophobia between the two eyes in 78% of patients. Twelve percent of the patients had greater photophobia in the eye with the peripheral iridectomy, and 10% had greater photophobia in the eye with the sector iridectomy. 相似文献
37.
Pulmonary effects of chronic exposure to airborne cadmium 总被引:1,自引:0,他引:1
In haemoglobinometry grave errors are still being made even though an internationally accepted standardized method is available for the determination of the haemoglobin content of blood. Up to the present only haemiglobincyanide reference solutions have been available on a wide scale to check the measuring stage of the standardized haemiglobincyanide method. These reference solutions are shown to remain stable, under proper storage conditions, for more than 10 years. Concentrated haemoglobin solutions have become available recently, offering the possibility to control the dilution and conversion steps of the haemiglobincyanide method. Such a solution is shown to remain stable, under proper storage conditions, for at least a year. Using both haemiglobincyanide reference solutions and concentrated haemoglobin solutions, as well as having the possibility of checking the cyanide content of the reagent used, an acceptable intra-laboratory control program may now be set up. 相似文献
38.
The cheating and intention of a partner as determinants of evaluative decisions among juvenile offenders 总被引:1,自引:0,他引:1
A 17 year-old male, who was mentally and bodily retarded from the age of 7 years. At the age of 16 years, several neurological signs appeared. Pathologically, there was widespread myelin loss and tissue sponginess in the white matter of the cerebrum and cerebellum, bilaterally and symmetrically. A great many Alzheimer type II glia and Opalski glia were widely distributed in the cerebral cortex and the basal ganglia. Despite severe destruction of the white matter, mesenchymal and gliofibre proliferation were not noticed. In the liver, Laennec's cirrhosis and a great many copper granules in the cytoplasm of the parenchymal cells were identified. From the above mentioned findings the present case, being a new type, could be called "Demyelinating type of Wilson's disease". 相似文献
39.
40.
Antigenic analysis of Chlamydia psittaci, C. trachomatis, and Lymphogranuloma venereum (LGV) revealed basic physicochemical differences among the three chlamydial strains. These were manifested in structural, isoelectric points, absorption spectra, and in the characteristics of the chromophobe-containing proteins. The effective period of sonication for C. psittaci and C. trachomatis is around 60 min during which the linkages most susceptible to external sonication forces were broken, releasing all attainable cellular components. Denaturation studies demonstrated that less than 50% of protein content of C. psittaci was denatured after 1 h of sonication, only 5% in the case of C. trachomatis. The protein and carbohydrate content of the most reactive fractions in macrophage-spreading inhibition test were different for LGV and C. trachomatis. The structural differences appear to determine the antigenic properties observed among the chlamydial strains as well as the specificity and probably the mechanisms (s) of cellular immune reactivity to Chlamydiae. This in turn may explain the failure of chlamydial vaccines, prepared from stock strains, to protect immunized children against 'wild' chlamydial strains. 相似文献