全文获取类型
收费全文 | 4411篇 |
免费 | 35篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 14篇 |
综合类 | 15篇 |
化学工业 | 116篇 |
金属工艺 | 28篇 |
机械仪表 | 43篇 |
建筑科学 | 38篇 |
矿业工程 | 15篇 |
能源动力 | 18篇 |
轻工业 | 103篇 |
水利工程 | 8篇 |
石油天然气 | 32篇 |
武器工业 | 1篇 |
无线电 | 71篇 |
一般工业技术 | 126篇 |
冶金工业 | 3738篇 |
原子能技术 | 15篇 |
自动化技术 | 77篇 |
出版年
2023年 | 7篇 |
2022年 | 22篇 |
2021年 | 28篇 |
2020年 | 17篇 |
2019年 | 17篇 |
2018年 | 24篇 |
2017年 | 22篇 |
2016年 | 28篇 |
2015年 | 26篇 |
2014年 | 25篇 |
2013年 | 51篇 |
2012年 | 40篇 |
2011年 | 50篇 |
2010年 | 44篇 |
2009年 | 37篇 |
2008年 | 43篇 |
2007年 | 31篇 |
2006年 | 31篇 |
2005年 | 33篇 |
2004年 | 21篇 |
2003年 | 16篇 |
2002年 | 16篇 |
2001年 | 9篇 |
2000年 | 16篇 |
1999年 | 117篇 |
1998年 | 1233篇 |
1997年 | 719篇 |
1996年 | 420篇 |
1995年 | 250篇 |
1994年 | 196篇 |
1993年 | 213篇 |
1992年 | 46篇 |
1991年 | 26篇 |
1990年 | 43篇 |
1989年 | 36篇 |
1988年 | 49篇 |
1987年 | 38篇 |
1986年 | 37篇 |
1985年 | 35篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 16篇 |
1981年 | 19篇 |
1980年 | 25篇 |
1978年 | 12篇 |
1977年 | 84篇 |
1976年 | 153篇 |
1975年 | 13篇 |
1973年 | 3篇 |
1955年 | 3篇 |
排序方式: 共有4458条查询结果,搜索用时 15 毫秒
81.
82.
83.
A carefully controlled comparative study showed miconazole nitrate 2% vaginal cream (Monistat) to be a highly effective agent in the treatment of vaginal candidiasis in pregnant subjects. Miconazole nitrate was significantly more effective than nystatin (Mycostatin) in the treatment of vaginal candidiasis in all three trimesters of pregnancy, and also more effective regardless of whether the candidal infection was primary or recurrent. Observations relating to the safety of this therapy during pregnancy were made and discussed. 相似文献
84.
Cryotherapy is used in treatment of chronic rhinitis and pharyngitis. The effect of cryotherapy on the qualitative and quantitative composition of the microflora was studied. Staphylococci prevailed in the rhinitis patients, streptococci, Clebsiella and Neisseria being registered more rarely. The staphlococcal isolates were highly sensitive to monomycin, neomycin, erythromycin and levomycetin. The results of the dynamic study showed that the flora composition did not significantly change during cryotherapy and the sensitivity level of the staphylococcal isolates to the antibodies remained unchanged. 相似文献
85.
SA Gelfand 《Canadian Metallurgical Quarterly》1977,83(5-6):480-487
The precision of the Rinne test at 128-2048 Hz was studied in 100 ears with confirmed conductive pathologies. The number of negative (diagnostic) Rinnes decreased significantly with fall in frequency. While there were significantly more negative than positive Rinnes at 128 and 256 Hz, there were significantly more positive results at higher frequencies; indicating that the Rinne is not reliably diagnostic above 256 Hz. However, the possibility of vibrotactile responses must be remembered with low frequency tuning forks. Also, conductive lesions manifested as high tone air-bone gaps will not be identified with low frequency Rinne tests. Air-bone gaps of 25 to 40 dB, depending on frequency, are necessary for the Rinne to identify the presence of conductive components in most cases. Gaps of 25-30 dB for 128 Hz; 35-40 dB for 256 Hz; 55-60 dB for 512 Hz; and 45-50 dB for 1024 Hz, are necessary for the Rinne to meet a 75% correct detection criterion. The 2o48 Hz Rinne does not attain even chance detection. The Rinne test cannot be validly employed as a criterion against which other measures can be evaluated. 相似文献
86.
87.
88.
89.
Aspergillus terreus infection limited to the L1-2 disk space and first and second lumbar vertebrae developed in a patient not predisposed to invasive aspergillosis. The observation of morphologically distinct secondary spores (aleuriospores) on microscopic examination of open biopsy specimens permitted a preliminary identification of A terreus, which was confirmed by culture. The infection was eradicated with amphotericin B in a total dose of 3 gm. Aspergillus terreus is usually a saprophyte. The present case and four others collected from the literature establish this species as an invasive pathogen. 相似文献
90.
AM Attallah H Ismail SA El Masry H Rizk A Handousa M El Bendary A Tabll F Ezzat 《Canadian Metallurgical Quarterly》1999,37(2):354-357
Schistosoma circulating antigens were used to indicate the infection intensity and to assess cure. An immunoglobulin G2a (IgG2a) mouse monoclonal antibody was used in a fast dot-enzyme-linked immunosorbent assay (ELISA; FDA) for rapid and simple diagnosis of schistosomiasis in the field. Seven hundred Egyptians were parasitologically examined for Schistosoma mansoni and other parasitic infections. A rectal biopsy was done as a "gold standard" for individuals showing no S. mansoni eggs in their feces. Egg counts were obtained by the Kato smear method for only 100 of 152 individuals with eggs in their feces. Specific anti-schistosome IgG antibodies were evaluated in sera by ELISA. Urine samples from the 700 individuals were tested by FDA for detection of the circulating antigen. The assay showed a sensitivity of 93% among 433 infected individuals and a specificity of 89% among 267 noninfected individuals. FDA showed the highest efficiency of antigen detection (91%) compared with the efficiency of antibody detection by ELISA (75%) and stool analysis (60%). In addition, FDA detected infected patients with 20 eggs/g of feces. Also, the sensitivity of FDA ranged from 90 to 94% among samples from patients with different clinical stages of schistosomiasis. All the assay steps can be completed within 30 min at room temperature for 96 urine samples. The monoclonal antibody identified a 74-kDa antigen in different antigenic extracts of S. mansoni and Schistosoma haematobium and in the urine of infected individuals. In addition, a 30-kDa degradation product was identified only in the urine samples. On the basis of these results, FDA should be used as a rapid tool for the sensitive and specific diagnosis of Schistosoma infection. 相似文献