全文获取类型
收费全文 | 2818篇 |
免费 | 3篇 |
专业分类
化学工业 | 17篇 |
建筑科学 | 1篇 |
能源动力 | 1篇 |
轻工业 | 12篇 |
石油天然气 | 1篇 |
无线电 | 20篇 |
一般工业技术 | 17篇 |
冶金工业 | 2748篇 |
自动化技术 | 4篇 |
出版年
2023年 | 1篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 3篇 |
2017年 | 2篇 |
2016年 | 2篇 |
2014年 | 1篇 |
2011年 | 3篇 |
2008年 | 2篇 |
2007年 | 2篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 5篇 |
2003年 | 7篇 |
2002年 | 2篇 |
2000年 | 1篇 |
1999年 | 79篇 |
1998年 | 823篇 |
1997年 | 475篇 |
1996年 | 294篇 |
1995年 | 163篇 |
1994年 | 145篇 |
1993年 | 183篇 |
1992年 | 21篇 |
1991年 | 35篇 |
1990年 | 45篇 |
1989年 | 45篇 |
1988年 | 41篇 |
1987年 | 34篇 |
1986年 | 23篇 |
1985年 | 24篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 11篇 |
1981年 | 15篇 |
1980年 | 32篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1977年 | 74篇 |
1976年 | 186篇 |
1975年 | 6篇 |
1972年 | 1篇 |
1967年 | 2篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1961年 | 1篇 |
1955年 | 2篇 |
排序方式: 共有2821条查询结果,搜索用时 12 毫秒
41.
Cholera in Portugal, 1974.I. Modes of transmission 总被引:4,自引:0,他引:4
PA Blake ML Rosenberg JB Costa PS Ferreira CL Guimaraes EJ Gangarosa 《Canadian Metallurgical Quarterly》1977,105(4):337-343
In April-November 1974, Portugal had a cholera epidemic caused by Vibrio cholerae El Tor Inaba with 2467 bacteriologically confirmed hospitalized cases and 48 deaths. Most of the country was affected, with 17 of the 18 districts reporting cases. V. cholerae was isolated from 42 per cent of shellfish tested during the epidemic, and an epidemiologic study found that a history of consumption of raw or poorly cooked cockles was significantly more common among cholera patients than among paired controls. Water from a spring and a brand of commercially bottled water were also found to be vehicles of transmission of cholera. Although night soil was sometimes used on gardens, consumption of raw fruits and vegetables was not associated with illness. 相似文献
42.
Thirty children seen between 1954 and 1970 with the diagnosis of anorexia nervosa were contacted between five and twenty years after initial treatment. Patients outcomes in terms of education, weight in adulthood, medical problems, marriage, psychiatric treatment, and recurrence of anorexia were surveyed. Results corroborate those of earlier studies suggesting that adjustment in adulthood is related to personality type. 相似文献
43.
44.
The formation of androgen-binding protein (ABP) by cultured Sertoli cells, prepared from testes of immature rats, is increased when androgens or follicle-stimulating hormone (FSH) are present in the medium. Testosterone and 5alpha-dihydrotestosterone are equally effective in stimulating the synthesis and secretion of ABP, but non-androgenic steroids examined (progesterone, 17beta-estradiol and corticosterone) are without influence. Maximal increases are observed when androgens are added at the time of cell plating. Cells maintained in culture medium devoid of hormones become progressively less sensitive to subsequent addition of testosterone or FSH. Data are discussed in relation to the sites of androgen requirements for spermatogenesis. 相似文献
45.
AA Hakim CB Papeleux JB Lane N Lifson ME Yablonski 《Canadian Metallurgical Quarterly》1977,233(5):E416-E421
The relationships between luminal hydrostatic pressure and fluid transport by dog jejunum in vivo studied as a sheet in the Wells clamp were compared with quantitative predictions from a model proposed for the mechanism of the secretion produced by elevated venous pressure. According to the model, the secretion produced by increasing venous pressure and the secretion produced by negative luminal pressure are both passive filtrates contingent on a transepithelial pressure of a few centimeters of H2O. We consider that the agreement between the observed and predicted responses to luminal pressure provides strong support for the model. In particular, a) the observations displayed a predicted gross asymmetry in rates of fluid transfer with isotonic fluids depending on whether the luminal pressure was positive or negative; b) the observed magnitude of the negative luminal pressure required for the onset of secretion agreed with predictions; and c) the secretion contained significant amounts of protein at about 25% of the plasma concentration. 相似文献
46.
The design and calibration of thin-film Zr transmission filters for the Cosmic Hot Interstellar Plasma Spectrometer (CHIPS) spaceborne astronomical telescope is presented. The transmission of a 1,000-A-thick Zr filter is measured for wavelengths from 45 to 1,304 A as well as its variability with respect to expected space-flight enviromental extremes of temperature, vibration, and atomic O bombardment. For the CHIPS spectral band of 90-260 A, the transmission of the Zr fiter is deemed useful between 90 and 200 A and is stable with respect to expected temperature and vibrational changes. The maximum atomic O bombardment decreases the filter transmission between 90 and 130 A by approximately 20% and does not appreciably affect the rest of the CHIPS bandpass. These results make Zr an acceptable filter candidate for CHIPS. 相似文献
47.
JB Tebbetts 《Canadian Metallurgical Quarterly》1998,102(5):1690-1697
Numerous complications and increased operating times were reported with ultrasonically assisted lipoplasty in the first several months after introduction of the technology in the United States. The purpose of this study was to review early reported complications and management regimens, evaluate possible causes of problems, and apply indications and techniques to attempt to minimize complications during an initial experience with this technique beginning in January of 1997. Seven specific indications and modifications of existing techniques were developed and applied to an initial clinical series of 70 consecutive patients who underwent ultrasound-assisted suction lipoplasty between January 10, 1997, and August 1, 1997. Follow-up ranged from 1 to 7 months. No perioperative or postoperative complication occurred in any patient in this series. In this series of ultrasound-assisted lipoplasty cases, application of the following criteria resulted in a series of 70 patients with 1 to 7-month follow-up without complications: (1) selecting patients with well localized fat deposits who were no more than 20 percent above their ideal body weight; (2) infusing a solution of Ringer's Lactate containing 1 cc of 1:1000 epinephrine per 1000 cc into the area of fat removal, stopping infusion when the tissues first become firm, not infusing to marked tissue turgor or skin induration; (3) restricting the level of energy application to a minimum of 1 cm from the undersurface of the dermis; (4) limiting ultrasonic energy application in each area to approximately 1 minute per estimated 100 cc of total aspirate in a wet to superwet environment; (5) not performing ultrasound-assisted lipoplasty in the same area as another procedure that could potentially compromise tissue vascularity; (6) using a Lysonix 2000 generator and 5-mm golf tee tip probe at a power setting of 8 to apply ultrasonic energy to the area of fat removal, ceasing energy application when tissue resistance to the passage of the probe decreases and moving the cannula as rapidly as tissue resistance allows; and (7) using a standard elastic garment without adherent foam or other materials for 2 weeks postoperatively, encouraging all normal activity immediately, and restricting aerobic activities for 2 weeks. 相似文献
48.
49.
JM Mariner JB McMahon BR O'Keefe K Nagashima MR Boyd 《Canadian Metallurgical Quarterly》1998,248(3):841-845
Concentrations of the potent, HIV(human immunodeficiency virus) inactivating protein, cyanovirin-N (CV-N), which completely inhibit HIV-1 infectivity, do not block the binding of soluble CD4-receptor (sCD4) to HIV-1 lysates nor the attachment of intact HIV-1 virions to several target T-cell lines. Furthermore, in contrast to the known disassociative effects of sCD4 on viral envelope glycoproteins, treatment of HIVRF with high concentrations of CV-N results in complete viral inactivation but without apparent shedding of gp120 or other ultrastructural changes. These results are consistent with the view that the virucidal effects of CV-N result from interference with step(s) in the fusion process subsequent to the initial binding of the virus to target cells. 相似文献
50.
BACKGROUND: We determined the effect of oral ingestion of sucrose polyester, which was approved as a fat replacer in the United States, on gallbladder motility and on the release of cholecystokinin, the hormone that mediates gallbladder emptying. OBJECTIVE: Our objective was to measure effects of sucrose polyester on gallbladder emptying and cholecystokinin release. DESIGN: Eight healthy volunteers (3 men and 5 women) drank 60 mL sucrose polyester, digestible fat, or saline solution in a balanced crossover design on 3 separate days. RESULTS: Mean (+/-SEM) gallbladder emptying, when integrated over time, was low in response to both sucrose polyester (-150 +/- 214 mL x 120 min) and saline solution (-89 +/- 123 mL x 120 min). In contrast, there was marked emptying in response to digestible fat (1069 +/- 253 mL x 120 min). Sucrose polyester did not affect plasma cholecystokinin concentrations (-9.3 +/- 15.0 pmol x 120 min/L), whereas digestible fat resulted in a significant increase (89.5 +/- 44.8 pmol x 120 min/L, P = 0.014) compared with saline solution (-3.0 +/- 13.8 pmol x 120 min/L). CONCLUSIONS: Ingestion of sucrose polyester, in contrast with digestible fat, did not stimulate gallbladder emptying or release of cholecystokinin. 相似文献