全文获取类型
收费全文 | 6387篇 |
免费 | 1篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 28篇 |
能源动力 | 1篇 |
轻工业 | 5篇 |
石油天然气 | 3篇 |
无线电 | 3篇 |
一般工业技术 | 6篇 |
冶金工业 | 6332篇 |
自动化技术 | 8篇 |
出版年
2019年 | 1篇 |
2017年 | 1篇 |
2011年 | 1篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 4篇 |
2004年 | 7篇 |
2003年 | 2篇 |
1999年 | 179篇 |
1998年 | 2021篇 |
1997年 | 1130篇 |
1996年 | 726篇 |
1995年 | 370篇 |
1994年 | 327篇 |
1993年 | 385篇 |
1992年 | 41篇 |
1991年 | 93篇 |
1990年 | 68篇 |
1989年 | 77篇 |
1988年 | 76篇 |
1987年 | 84篇 |
1986年 | 72篇 |
1985年 | 69篇 |
1984年 | 3篇 |
1983年 | 12篇 |
1982年 | 34篇 |
1981年 | 44篇 |
1980年 | 38篇 |
1979年 | 2篇 |
1978年 | 17篇 |
1977年 | 158篇 |
1976年 | 317篇 |
1975年 | 13篇 |
1965年 | 1篇 |
1955年 | 7篇 |
排序方式: 共有6388条查询结果,搜索用时 0 毫秒
51.
52.
Purified Semliki forest virus in aerosols is inactivated rapidly at 40% and above 70% relative humidity. At all humidities tested the decay of virus infectivity runs parallel with the decrease in hemagglutination activity, whereas the biological integrity of the virus ribonucleic acid is preserved. Also, free infectious ribonucleic acid is stable after spraying at all relative humidities. Evidence is presented for the hypothesis that above 20% relative humidity, virus inactivation in aersols is mainly due to surface-dependent factors, damaging the virus coat. 相似文献
53.
Induction of labor by acupuncture electro-stimulation was carried out in 31 patients. This was successful in 21 cases. The pattern of uterine contractions induced in these patients was similar to that in normal labor. No serious fetal or maternal complications occurred. The delay between the commencement of stimulation and the onset of contractions suggests that a humoral mechanism may be involved. 相似文献
54.
JC Arbo 《Canadian Metallurgical Quarterly》1976,96(19-21):1075-1078
55.
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
56.
57.
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
58.
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
59.
60.
Colon atresia is a rare cause of intestinal obstruction in the neonate and requires early diagnosis and prompt surgical treatment. It is impossible in the neonate to differentiate colon atresia from other forms of obstruction at the time of initial presentation. The diagnosis is confirmed roentgenographically, including views of the abdomen and contrast barium enema series. Lesions proximal to the splenic flexure are treated with initial resection of the atretic segment and a primary anastomosis. Those lesions distal to the splentic flexure are managed initally with a diverting loop colostomy with subsequent staged resection and anastomosis. 相似文献