全文获取类型
收费全文 | 970篇 |
免费 | 1篇 |
专业分类
电工技术 | 1篇 |
化学工业 | 47篇 |
金属工艺 | 9篇 |
机械仪表 | 1篇 |
轻工业 | 5篇 |
水利工程 | 2篇 |
石油天然气 | 15篇 |
无线电 | 7篇 |
一般工业技术 | 19篇 |
冶金工业 | 861篇 |
原子能技术 | 1篇 |
自动化技术 | 3篇 |
出版年
2022年 | 5篇 |
2021年 | 12篇 |
2020年 | 2篇 |
2018年 | 5篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 2篇 |
2012年 | 3篇 |
2011年 | 3篇 |
2010年 | 2篇 |
2009年 | 5篇 |
2008年 | 1篇 |
2007年 | 6篇 |
2006年 | 8篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 4篇 |
2002年 | 1篇 |
2001年 | 1篇 |
2000年 | 2篇 |
1999年 | 8篇 |
1998年 | 268篇 |
1997年 | 143篇 |
1996年 | 112篇 |
1995年 | 69篇 |
1994年 | 48篇 |
1993年 | 55篇 |
1992年 | 12篇 |
1991年 | 22篇 |
1990年 | 17篇 |
1989年 | 10篇 |
1988年 | 7篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1982年 | 10篇 |
1981年 | 6篇 |
1980年 | 8篇 |
1978年 | 5篇 |
1977年 | 27篇 |
1976年 | 42篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1970年 | 1篇 |
1967年 | 2篇 |
1965年 | 1篇 |
排序方式: 共有971条查询结果,搜索用时 0 毫秒
81.
The maximum watts factor (WFmax) is often used to characterize detrusor contractility. It was recently shown that the WFmax may increase in some patients with chronic outlet obstruction. It is, however, unclear whether this increase reflects a dependence of the WFmax on the degree of outlet obstruction or whether it represents a true increase in detrusor contractility secondary to chronic outlet obstruction. Therefore, this study was performed to investigate this issue using a canine model of acute outlet obstruction. Urodynamic studies were performed on adult canines with surgically exposed lower urinary tracts. Pressure transducers were used to measure the intravesical and the distal urethral pressures, whereas an ultrasonic flow meter was used to obtain a simultaneous measure of the urinary flow rate. Detrusor contractions were induced by electrically stimulating the pelvic nerves bilaterally. Varying degrees of outlet obstruction were created using an inflatable sphincter cuff secured around the bladder outlet. The WFmax, the detrusor pressure at voiding terminus (Pdet.clos), and the passive urethral resistance (R) were computed from measured pressure-flow rate data at each degree of outlet obstruction. The WFmax was not significantly correlated to either the sphincter cuff volume (r = 0.025, p = 0.871), the Pdet.clos (r = 0.286, p = 0.073) or the R (r = 0.110, p = 0.509). The WFmax was not significantly different among mild, moderate, and severe degrees of outlet obstruction (p = 0.176). Our results suggest that the WFmax is independent of the degree of acute outlet obstruction (defined in terms of the sphincter cuff volume, Pdet.clos and R). This validates the current practice of using the WFmax to evaluate detrusor function in patients with voiding dysfunction regardless of outlet resistance. Further, since the WFmax is independent of outlet obstruction acutely, it is reasonable that it would also be independent of outlet obstruction under chronic conditions. Our results, therefore, also imply that the increase in the WFmax with chronic outlet obstruction may represent a true increase in detrusor contractility and not a WFmax dependence on outlet resistance. 相似文献
82.
CE Cox S Pendas NN Ku DS Reintgen HS Greenberg SV Nicosia 《Canadian Metallurgical Quarterly》1998,64(6):533-7; discussion 537-8
Successful breast conservation therapy with optimal cosmesis requires adequate tumor excision and negative tumor margins. Therefore, more sensitive techniques are being developed to identify lumpectomy margins intraoperatively with greater accuracy. Unidentified microscopic disease is seemingly responsible for a local recurrence rate of up to 25 per cent 3 to 5 years after lumpectomy and radiotherapy for breast cancer patients. As a result, Moffitt Cancer Center has routinely used an intraoperative touch preparation cytology (TPC) protocol to evaluate the entire resected surface of all lumpectomies. In addition, resection margins were also evaluated by gross examination and by standard histology. In rare instances frozen sections were used to evaluate tumor margins. In this study 701 consecutive lumpectomy specimens were evaluated by TPC during the period of 9 years with a mean follow-up of 3.5 years. Local cancer recurrence was 2.7 per cent (mean recurrence, 2.53 years), in women whose lumpectomy margins were evaluated by TPC. Of interest, a local recurrence rate of 14.6 per cent was observed in patients who had referral lumpectomies evaluated by conventional histopathology. This study suggests that accurate margin assessment with TPC plays an important role in the control of local recurrence after breast conservation therapy. Therefore, we conclude the routine use of intraoperative TPC provides rapid, reliable, topographically accurate identification of residual microscopic disease at lumpectomy margins. 相似文献
83.
We examined the localization of phosphotyrosine (p-Tyr)-modified proteins in the normal corneal epithelium using affinity-purified rabbit anti-p-Tyr antibody. Normal rat cornea was fixed and semi-thin and ultra-thin frozen sections were prepared. Immunofluorescence microscopy showed that p-Tyr was distributed along the cell membrane of the corneal epithelium. Immunogold electron microscopy revealed that the labeling is exclusively localized in the desmosomes and hemidesmosomes. A fraction enriched with desmosomes was extracted from the bovine corneal epithelium and examined by Western blotting. Immunoblotting for p-Tyr showed eight prominent bands (290, 200, 190, 115, 85, 62, 50, and 47 kD) in the desmosomal fraction. The enrichment of p-Tyr in desmosomes and hemidesmosomes of the corneal epithelium suggests that these cell-to-cell and cell-to-substrate junctions are involved in signal transduction. 相似文献
84.
85.
86.
S Milberger J Biederman SV Faraone T Wilens MP Chu 《Canadian Metallurgical Quarterly》1997,6(4):318-329
This article investigates the relationship between attention-deficit/hyperactivity disorder (ADHD) and psychoactive substance use disorders (PSUD) in siblings of ADHD and normal-control probands and addresses issues of psychiatric comorbidity and gender. Using DSM-III-R structured diagnostic interviews and blind raters, the authors conducted a 4-year follow-up of siblings. ADHD and male gender predicted higher rates and an earlier onset of PSUD after adjusting for high-risk status, other psychiatric disorders, and age. Risk was particularly high if the siblings had ADHD plus conduct disorder. This study's findings confirms the authors' prior report high-lighting the importance of drug and alcohol prevention and cessation programs aimed at ADHD youth and their siblings, particularly those with comorbid conduct disorder. 相似文献
87.
Setting up a puppy training program is one of the most important services veterinarians can offer. Puppy socialization classes aim not only to socialize the puppies so that they learn to interact well with children, adults, and other dogs, but also to teach basic obedience exercises. The classes build a strong bond between puppy, owner, and veterinary clinic. This article covers the techniques used, the structure of the classes, and outlines benefits for the dog, owner, veterinarian, and community. 相似文献
88.
89.
90.