全文获取类型
收费全文 | 2581篇 |
免费 | 6篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 30篇 |
金属工艺 | 3篇 |
机械仪表 | 4篇 |
建筑科学 | 15篇 |
矿业工程 | 1篇 |
能源动力 | 6篇 |
轻工业 | 34篇 |
水利工程 | 2篇 |
无线电 | 10篇 |
一般工业技术 | 29篇 |
冶金工业 | 2421篇 |
原子能技术 | 2篇 |
自动化技术 | 30篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 4篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2017年 | 7篇 |
2016年 | 5篇 |
2015年 | 4篇 |
2014年 | 3篇 |
2013年 | 20篇 |
2012年 | 5篇 |
2011年 | 11篇 |
2010年 | 4篇 |
2009年 | 6篇 |
2008年 | 10篇 |
2007年 | 4篇 |
2006年 | 5篇 |
2005年 | 7篇 |
2004年 | 3篇 |
2003年 | 8篇 |
2000年 | 2篇 |
1999年 | 79篇 |
1998年 | 714篇 |
1997年 | 445篇 |
1996年 | 280篇 |
1995年 | 152篇 |
1994年 | 132篇 |
1993年 | 150篇 |
1992年 | 14篇 |
1991年 | 24篇 |
1990年 | 31篇 |
1989年 | 25篇 |
1988年 | 24篇 |
1987年 | 19篇 |
1986年 | 15篇 |
1985年 | 20篇 |
1983年 | 9篇 |
1982年 | 15篇 |
1981年 | 9篇 |
1980年 | 28篇 |
1979年 | 7篇 |
1978年 | 10篇 |
1977年 | 64篇 |
1976年 | 159篇 |
1975年 | 6篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1970年 | 3篇 |
1969年 | 2篇 |
1959年 | 2篇 |
排序方式: 共有2588条查询结果,搜索用时 15 毫秒
91.
M Garofalo R Borioni A Penta Peppo GM Actis Dato P Tempesta L Chiariello 《Canadian Metallurgical Quarterly》1995,37(4):202-203
Femoral artery lesions may occur after cardiac catheterization or percutaneous transluminal coronary angioplasty (PTCA). The incidence of pseudoaneurysm following transfemoral catheterization ranges from 0.21 to 6.25%. Among 3162 cardiac catheterization procedures thirteen (0.41%) patients presented a femoral pseudoaneurysm requiring surgical repair. The Authors reported their technical consideration about the utility of extraperitoneal iliac control during surgical repair of femoral artery pseudoaneurysm due to cardiac catheterization. 相似文献
92.
93.
CW Critchlow CM Surawicz KK Holmes J Kuypers JR Daling SE Hawes GM Goldbaum J Sayer C Hurt C Dunphy 《Canadian Metallurgical Quarterly》1995,9(11):1255-1262
OBJECTIVE: To determine the risk of developing high grade anal squamous intraepithelial neoplasia (HG-AIN) in relation to HIV infection and immunosuppression, after controlling for the effects of human papillomavirus (HPV) infection. DESIGN: Prospective cohort study of 158 HIV-seropositive and 147 HIV-seronegative homosexual men presenting to a community-based clinic with initially negative anal cytologic and colposcopic findings. METHODS: Subjects completed self-administered questionnaires, underwent cytologic screening, and standardized unaided and colposcopic examination of the proximal anal canal for presence of abnormalities suggestive of AIN. Anal specimens were screened for HPV DNA. RESULTS: HG-AIN developed in eight (5.4%) and 24 (15.2%) HIV-seronegative and -seropositive men, respectively. Risk of HG-AIN among HIV-seronegative men was associated with detection of anal HPV types 16 or 18 by Southern transfer hybridization (STH), detection of HPV 16 or 18 at the lower levels by polymerase chain reaction but not by STH, and with number of positive HPV tests; HG-AIN risk among HIV-seropositive men was associated with detection of HPV 16 or 18 only by STH, detection of HPV types other than 16 or 18, CD4 count < or = 500 x 10(6)/l, and number of positive HPV tests. HIV-induced immunosuppression remained an independent predictor of HG-AIN after adjusting for type and level of detection of HPV; HIV infection predicted HG-AIN risk after adjustment for number of positive HPV tests. CONCLUSIONS: The association of HG-AIN with HIV, independent of HPV type, level of HPV detection and number of positive HPV tests, suggests that this increased risk cannot be entirely explained by an effect of HIV on HPV detection. Future studies focusing on factors more specific to the local microenvironment in the anal canal should help clarify these issues. 相似文献
94.
The airway functions in pregnancy have been widely studied but reports obtained from Western and Indian population show divergence. While the Indian populations show significant changes in total and timed vital capacity (FVC and FEV1), the Western counterparts dismiss such changes as insignificant. Our results show insignificant alteration in airway function and support the results reported for Western population. 相似文献
95.
96.
97.
When subjects track with the eyes an arm-attached target, eye latency is shorter than when tracking an external target. This improved synchrony could result from either a common command addressed to the two systems or from an influence of the arm command on eye motion initiation. According to the first hypothesis, the eyes should start moving long before the arm, because of the difference in dynamics. We recorded arm and eye motion together with biceps muscle activity in controls and a deafferented subject. Data support the second hypothesis. Moreover, the deafferented subject showed a lesser correlation between arm and eye motions than controls, suggesting a role for arm proprioception in the calibration of the temporal relationship between arm and eye movements. 相似文献
98.
OBJECT: A current hypothesis for the genesis of muscular complaints in the shoulder/neck region postulates that short periods with a completely relaxed muscle are essential to avoid complaints. Another hypothesis is that these disorders are related to psychosocial conditions at work. In order to test these hypotheses, 23 medical secretaries were investigated. METHODS: The load pattern during work in the upper trapezius muscle bilaterally was assessed with electromyographic (EMG) technique and exposure variation analysis (EVA). In addition, pressure pain threshold (PPT) was measured on the trapezius muscle bilaterally and on the sternum. Psychosocial conditions at work were assessed with a questionnaire. RESULTS: The medical secretaries with complaints had significantly fewer episodes with totally or close to totally relaxed muscle compared with the healthy group. The group with complaints tended to have a more monotonous load pattern at low levels (approx. 1%-5% maximum voluntary contraction) while the healthy group had more frequent pauses but also somewhat more frequent short load peaks. The group with complaints showed lower PPT readings compared with the healthy group. However, the whole group had considerably lower PPTs than is usually reported in the literature. Of the 12 questions in the psychosocial questionnaire only one regarding work task satisfaction showed a significant difference between the two groups. CONCLUSION: Support is found for hypothesis that secretaries without complaints have more frequent episodes with totally relaxed muscle. A significant difference is found regarding work task satisfaction. 相似文献
99.
100.