全文获取类型
收费全文 | 4948篇 |
免费 | 52篇 |
国内免费 | 3篇 |
学科分类
工业技术 | 5003篇 |
出版年
2021年 | 15篇 |
2020年 | 16篇 |
2019年 | 22篇 |
2018年 | 25篇 |
2017年 | 37篇 |
2016年 | 28篇 |
2015年 | 18篇 |
2014年 | 32篇 |
2013年 | 129篇 |
2012年 | 57篇 |
2011年 | 102篇 |
2010年 | 77篇 |
2009年 | 85篇 |
2008年 | 103篇 |
2007年 | 101篇 |
2006年 | 89篇 |
2005年 | 96篇 |
2004年 | 79篇 |
2003年 | 76篇 |
2002年 | 86篇 |
2001年 | 59篇 |
2000年 | 61篇 |
1999年 | 135篇 |
1998年 | 725篇 |
1997年 | 476篇 |
1996年 | 288篇 |
1995年 | 201篇 |
1994年 | 183篇 |
1993年 | 196篇 |
1992年 | 68篇 |
1991年 | 56篇 |
1990年 | 72篇 |
1989年 | 70篇 |
1988年 | 60篇 |
1987年 | 59篇 |
1986年 | 59篇 |
1985年 | 79篇 |
1984年 | 66篇 |
1983年 | 42篇 |
1982年 | 37篇 |
1981年 | 57篇 |
1980年 | 51篇 |
1979年 | 32篇 |
1978年 | 34篇 |
1977年 | 108篇 |
1976年 | 206篇 |
1975年 | 28篇 |
1974年 | 26篇 |
1973年 | 18篇 |
1972年 | 22篇 |
排序方式: 共有5003条查询结果,搜索用时 15 毫秒
1.
The smooth muscle of the normal bladder wall must have some specific properties. It must be very compliant and able to reorganise itself during filling and emptying to accommodate the change in volume without generating any intravesical pressure, but whilst maintaining the normal shape of the bladder. It must be capable of synchronous activation to generate intravesical pressure at any length to allow voiding. The cells achieve this through spontaneous electrical activity combined with poor electrical coupling between cells, and a dense excitatory innervation. In the diseased state, alterations of the smooth muscle may lead to failure to store or failure to empty properly. The diseased states discussed are bladder instability and diabetic neuropathy. Bladder instability is characterised urodynamically by uninhibitable rises in pressure during filling, and is seen idiopathically and in association with bladder outflow obstruction and neuropathy. In diabetic neuropathy, many of the smooth muscle changes are a consequence of diuresis, but there is evidence for alterations in the sensory arm of the micturition reflex. In the unstable bladder, additional alterations of the smooth muscle are seen, which are probably caused by the patchy denervation that occurs. The causes of this denervation are not fully established. Nonsurgical treatment of instability is not yet satisfactory; neuromodulation has some promise, but is expensive, and the mechanisms poorly understood. Pharmacological treatment is largely through muscarinic receptor blockade. Drugs to reduce the excitability of the smooth muscle are being sought, since they may represent a better pharmacological option. 相似文献
2.
Coarse filters for shape matching 总被引:3,自引:0,他引:3
Corney J. Rea H. Clark D. Pritchard J. Breaks M. Macleod R. 《Computer Graphics and Applications, IEEE》2002,22(3):65-74
This article describes the coarse shape filters that support the 3D, Internet-based search engine ShapeSifter, which aims to locate parts already in production that have a shape similar to a desired new part. The search engine analyzes the target model's shape characteristics and performs a similarity match on the database's contents. Our main challenge is identifying shape metrics that produce effective characterizations of 3D models for similarity comparison. We focus on using three novel convex hull-based indices to carry out a preliminary coarse filtering of candidates prior to more detailed analysis. We also describe the crucial role played by two databases of benchmark objects. Unlike other shape-matching systems, we chose ShapeSifter's architecture (multistep query), 3D representation (triangulated mesh), and implementation (Java3D) to allow deployment online once it matures 相似文献
3.
Model-driven development - Guest editor's introduction 总被引:1,自引:0,他引:1
4.
Graduates of clinical training programs were surveyed to determine the degree to which they have found various graduate school experiences useful in their professional work. Samples of academic clinical psychologists and practicing clinical psychologists reported time allocation and preference for various professional activities, perceived usefulness of various theoretical orientations, and the influence on their current professional work of 19 different graduate training topics. Results suggest that where differences exist, academic clinical psychologists are generally more satisfied with Boulder-model-inspired scientific training than are clinical practitioners. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
The consumer health plan value survey: round two 总被引:2,自引:0,他引:2
6.
Lichen sclerosus is a chronic skin condition with a predilection for the genital area. In the present study, 35 male patients with lichen sclerosus were interviewed and examined. Blood screens were performed and histology was requested if not already performed. The findings indicate that lichen sclerosus in males exists as a spectrum of disease, ranging from a mild form with white plaques and few symptoms to a severe form with inflammation, atrophy and scarring with possible urological consequences. In many areas it differs from the condition in females; the association with autoimmune disease is weaker and there is less perianal and extragenital involvement. The association with malignancy in males is of lesser significance than initially believed. 相似文献
7.
EJ Clark 《Canadian Metallurgical Quarterly》1997,5(4):252-254
A method has been developed for the simultaneous analysis of the isomeric N-acetyl-S-(dichlorophenyl)cysteines (also known as dichlorophenylmercapturic acids, DCPMAs) in urine. This procedure allows the determination of 2,3- and 3,4-DCPMAs at the concentrations expected in the urine samples of employees occupationally exposed to 1,2-dichlorobenzene (1,2-DCB). The results of a 1,2-DCB exposure study under standardized conditions show a first-order kinetic for the excretion of DCPMAs, as well as acceptable linear correlations between the urinary concentrations of DCPMAs and the amount of inhaled 1,2-DCB. It therefore seems it would be possible to derive a biological tolerance value for 1,2-DCB based on isomeric DCPMAs as analytical parameters. 相似文献
8.
We have studied the inhibitory action of long- and short-chain fatty acids on hepatic glucose utilization in hepatocytes isolated from fasted rats. The rates of hepatic glucose phosphorylation and glycolysis were determined from the tritiated products of [2-3H] and [6-3H]glucose metabolism, respectively. The difference between these was taken as an estimate of the 'cycling' between glucose and glucose-6-phosphate. In the presence of 40 mM glucose this cycling was estimated at 0.68 mumol/min/g wet wt. Glucose phosphorylation was unaffected during palmitate and hexanoate oxidation to ketone bodies but glycolysis was inhibited. The rate of glucose cycling was increased during this phase to 1.25 mumol/min/g. Following the complete metabolism of the fatty acids, glycolysis was reinstated and cycling rates returned to control levels. Hepatic glucose cycling appears to be an important component of the glucose/fatty acid cycle. 相似文献
9.
10.
We study the topological rigidity of affine semigroups of algebraic actions. In the first part of the paper we given an algebraic condition for rigidity that unifies previous rigidity results and we settle an old question of Walters. In the second part we study a generalized notion of the rigidity of hyperbolic actions. 相似文献