全文获取类型
收费全文 | 8117篇 |
免费 | 45篇 |
国内免费 | 2篇 |
学科分类
工业技术 | 8164篇 |
出版年
2020年 | 14篇 |
2019年 | 15篇 |
2018年 | 19篇 |
2017年 | 14篇 |
2016年 | 19篇 |
2015年 | 21篇 |
2014年 | 21篇 |
2013年 | 78篇 |
2012年 | 23篇 |
2011年 | 33篇 |
2010年 | 25篇 |
2009年 | 24篇 |
2008年 | 54篇 |
2007年 | 38篇 |
2006年 | 38篇 |
2005年 | 31篇 |
2004年 | 39篇 |
2003年 | 50篇 |
2002年 | 29篇 |
2001年 | 18篇 |
2000年 | 23篇 |
1999年 | 242篇 |
1998年 | 2423篇 |
1997年 | 1376篇 |
1996年 | 859篇 |
1995年 | 444篇 |
1994年 | 365篇 |
1993年 | 451篇 |
1992年 | 61篇 |
1991年 | 71篇 |
1990年 | 82篇 |
1989年 | 67篇 |
1988年 | 71篇 |
1987年 | 66篇 |
1986年 | 60篇 |
1985年 | 53篇 |
1984年 | 19篇 |
1983年 | 33篇 |
1982年 | 34篇 |
1981年 | 41篇 |
1980年 | 74篇 |
1979年 | 16篇 |
1978年 | 22篇 |
1977年 | 156篇 |
1976年 | 307篇 |
1975年 | 26篇 |
1974年 | 11篇 |
1973年 | 13篇 |
1970年 | 9篇 |
1966年 | 12篇 |
排序方式: 共有8164条查询结果,搜索用时 15 毫秒
61.
62.
Resisting care is defined as any patient behavior which prevents or interferes with the care provider performing or assisting with ADLs for the patient, including bathing, eating, toileting, dressing and grooming. Significant consequences of resisting care include malnutrition, skin breakdown, dehydration, constipation and weight loss. Creativity, flexibility and patience are key components of any intervention. Due to the lability of the person with cognitive impairment, a plan that works perfectly one day may never work again. 相似文献
63.
We present a case where a Wiktor intracoronary stent was inserted for 'poor angiographic result' following balloon angioplasty. Despite appropriate positioning and repeated dilation of the stent a suboptimal result was achieved because of plaque herniation through the stent. The case emphasizes that the choice of stent used is important and will become more so as the number of choices available increases. 相似文献
64.
65.
66.
Pulmonary surfactant is a complex mixture of lipids and proteins that functions to keep alveoli from collapsing at the end of expiration. Dipalmitoylphosphatidylcholine has been identified as the most important component for lowering surface tension at the air-liquid interface. Hydrophobic surfactant apoproteins, SP-B and SP-C, play essential roles in the biophysical functions of the surfactant phospholipids. Hydrophilic surfactant apoproteins (SP-A and SP-D) that are members of C-type lectin superfamily, interact with phospholipids and glycolipids and modulate host defense functions in the lung. SP-A also plays an important role in regulating phospholipid homeostasis in the alveolar spaces. Recent advances in genetics and molecular biology have clarified the structure-function relationship of surfactant apoproteins. 相似文献
67.
68.
Kreppner Jana M.; Rutter Michael; Beckett Celia; Castle Jenny; Colvert Emma; Groothues Christine; Hawkins Amanda; O'Connor Thomas G.; Stevens Suzanne; Sonuga-Barke Edmund J. S. 《Canadian Metallurgical Quarterly》2007,43(4):931
Longitudinal analyses on normal versus impaired functioning across 7 domains were conducted in children who had experienced profound institutional deprivation up to the age of 42 months and were adopted from Romania into U.K. families. Comparisons were made with noninstitutionalized children adopted from Romania and with nondeprived within-U.K. adoptees placed before the age of 6 months. Specifically, the validity of the assessment, the degree of continuity and change in levels of functioning from 6 to 11 years, and the factors in the pre- and postadoption environment accounting for heterogeneity in outcome were examined. Pervasive impairment was significantly raised in children experiencing institutional deprivation for ≥6 months of life, with a minority within this group showing no impairment. There was no additional significant effect of duration of deprivation beyond the 6-month cutoff, and few other predictors explained outcome. The pattern of normality/impairment was mainly established by 6 years of age, with considerable continuity at the individual level between 6 and 11 years. The findings are discussed in terms of the possibility of a sensitive period for development. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
69.
W Stevens 《Quality Assurance: Good Practice, Regulation, and Law》2003,10(2):83-89
There has been a significant increase in the number of clinical drug trials (particularly phase III) being conducted in developing countries for infectious diseases such as HIV, malaria, and tuberculosis. Laboratory results provided by medical testing laboratories in the region are critical to ensuring the safety of patients and the generation of good quality data. A number of well accepted Good Clinical Practice (GCP) and Good Laboratory Practice (GLP) guidelines govern the conduct of clinical trials internationally. Good Clinical Practice guidelines remain too vague with respect to sample analysis to ensure practical implementation in these laboratories. In their strictest sense, Good Laboratory Practice guidelines refer to the analysis of samples from non-clinical studies. A specific set of minimum standards or requirements for practical implementation of clinical trial requirements in medical testing laboratories in the developing world is urgently required. 相似文献
70.
The sex ratio produced by an individual may be a consequence of relative frequencies of genotypes amongst offspring, or may result directly from parental (maternal) control. We analyse the evolutionarily stable sex ratio for a hypothetical organism in which both forms of sex ratio expression can occur. We prove that the point of expression of sex ratio does not affect the evolutionarily stable sex ratio for diploid hosts in populations infected with cytoplasmically inherited sex ratio distorters. 相似文献