全文获取类型
收费全文 | 7439篇 |
免费 | 467篇 |
国内免费 | 273篇 |
专业分类
8179篇 |
出版年
2023年 | 120篇 |
2022年 | 180篇 |
2021年 | 235篇 |
2020年 | 223篇 |
2019年 | 302篇 |
2018年 | 286篇 |
2017年 | 217篇 |
2016年 | 178篇 |
2015年 | 229篇 |
2014年 | 401篇 |
2013年 | 510篇 |
2012年 | 258篇 |
2011年 | 314篇 |
2010年 | 236篇 |
2009年 | 262篇 |
2008年 | 292篇 |
2007年 | 342篇 |
2006年 | 311篇 |
2005年 | 253篇 |
2004年 | 224篇 |
2003年 | 231篇 |
2002年 | 245篇 |
2001年 | 164篇 |
2000年 | 148篇 |
1999年 | 123篇 |
1998年 | 110篇 |
1997年 | 107篇 |
1996年 | 113篇 |
1995年 | 109篇 |
1994年 | 132篇 |
1993年 | 102篇 |
1992年 | 125篇 |
1991年 | 109篇 |
1990年 | 97篇 |
1989年 | 78篇 |
1988年 | 91篇 |
1987年 | 85篇 |
1986年 | 52篇 |
1985年 | 88篇 |
1984年 | 76篇 |
1983年 | 55篇 |
1982年 | 57篇 |
1981年 | 62篇 |
1980年 | 42篇 |
1979年 | 36篇 |
1978年 | 27篇 |
1977年 | 27篇 |
1976年 | 36篇 |
1973年 | 18篇 |
1972年 | 18篇 |
排序方式: 共有8179条查询结果,搜索用时 0 毫秒
81.
目的:建立检测人胎盘组织液氨基氮含量的方法,为产品质量控制和生产工艺稳定性提供判断手段。方法:加入福尔马林溶液后,以麝香草酚蓝为指示剂,用NaOH滴定液滴定。结果:当福尔马林溶液为中性、NaOH滴定液浓度为0.04mol/L时,甲醛滴定氨基氮的方法可靠。结论:本方法回收率高,操作简便,可以作为检测人胎盘组织液氨基氮含量的方法。 相似文献
82.
Milad Radiom Yong He Juan Peng-Wang Armelle Baeza-Squiban Jean-François Berret Yong Chen 《Biotechnology and bioengineering》2020,117(9):2827-2841
We report on the development of a new model of alveolar air–tissue interface on a chip. The model consists of an array of suspended hexagonal monolayers of gelatin nanofibers supported by microframes and a microfluidic device for the patch integration. The suspended monolayers are deformed to a central displacement of 40–80 µm at the air–liquid interface by application of air pressure in the range of 200–1,000 Pa. With respect to the diameter of the monolayers, that is, 500 µm, this displacement corresponds to a linear strain of 2–10% in agreement with the physiological strain range in the lung alveoli. The culture of A549 cells on the monolayers for an incubation time of 1–3 days showed viability in the model. We exerted a periodic strain of 5% at a frequency of 0.2 Hz for 1 hr to the cells. We found that the cells were strongly coupled to the nanofibers, but the strain reduced the coupling and induced remodeling of the actin cytoskeleton, which led to a better tissue formation. Our model can serve as a versatile tool in lung investigations such as in inhalation toxicology and therapy. 相似文献
83.
84.
Summary Presented here are techniques developed to culture and analyze three-dimensional (3-D) adipose-like tissues as a means to
bridge the gap between current liminations in culturing preadipocytes (PAs) and that of providing clinically relevant volumes
of adipose tissue useful for soft tissue engineering stratgies in reconstructive surgery. Pilot studies were performed to
determine techniques to visualize and analyze 3-D PA-like tissues as well as to develop successful strategies to culture 3T3-L1
cells in a high aspect ratio vessel rotating-wall bioreactor both with and without microcarriers. Next, a series of cultures
were accessed to verify these techniques as well as to compare the culture of the cells with and without microcarriers. Finally,
a perfused rotating-wall bioreactor was used to further investigate the nature of the aggregates or tissues being generated.
The aggregates that formed in the perfused system were analyzed via histology and in vivo animal studies. PA-like tissues
as large as 4–5 mm in diameter without microcarriers that were capable of lipid-loading and composed of viable cells were
achieved. We have successfully demonstrated that large tissue aggregates can be grown in bioreactor culture systems. 相似文献
85.
木质素单体合成的过程中涉及了许多酶的参与,而肉桂酰辅酶A还原酶(cinnamoyl-CoA reductase,CCR)是该过程中的一个关键酶。综述了CCR基因在植物体内的克隆、基因功能及在植物组织中的表达情况,并介绍了该基因在植物的抗病虫害和抗逆性研究、饲草和能源上的应用潜力,为进一步研究CCR基因生物学功能和利用奠定了基础。 相似文献
86.
Promoting extracellular matrix remodeling via ascorbic acid enhances the survival of primary ovarian follicles encapsulated in alginate hydrogels 下载免费PDF全文
87.
Guevara-Lora I 《Neurochemistry international》2012,61(1):72-78
The mediatory role of kinins in both acute and chronic inflammation within nervous tissues has been widely described. Bradykinin, the major representative of these bioactive peptides, is one of a few mediators of inflammation that directly stimulates afferent nerves due to the broad expression of specific kinin receptors in cell types in these tissues. Moreover, kinins may be delivered to a site of injury not only after their production at the endothelium surface but also following their local production through the enzymatic degradation of kininogens at the surface of nerve cells. A strong correlation between inflammatory processes and neurodegeneration has been established. The activation of nerve cells, particularly microglia, in response to injury, trauma or infection initiates a number of reactions in the neuronal neighborhood that can lead to cell death after the prolonged action of inflammatory substances. In recent years, there has been a growing interest in the effects of kinins on neuronal destruction. In these studies, the overexpression of proteins involved in kinin generation or of kinin receptors has been observed in several neurologic disorders including neurodegenerative diseases such Alzheimer's disease and multiple sclerosis as well as disorders associated with a deficiency in cell communication such as epilepsy. This review is focused on recent findings that provide reliable evidence of the mediatory role of kinins in the inflammatory responses associated with different neurological disorders. A deeper understanding of the role of kinins in neurodegenerative diseases is likely to promote the future development of new therapeutic strategies for the control of these disorders. An example of this could be the prospective use of kinin receptor antagonists. 相似文献
88.
89.
Burbaeva GSh Boksha IS Tereshkina EB Savushkina OK Starodubtseva LI Turishcheva MS Mukaetova-Ladinska E 《Neurochemical research》2007,32(9):1434-1444
We have used a systemic approach to establish a relationship between enzyme measures of glial glutamate and energy metabolism
(glutamine synthetase and glutamine synthetase-like protein, glutamate dehydrogenase isoenzymes, brain isoform creatine phosphokinase)
and two major glial proteins (glial fibrillary acidic protein and myelin basic protein) in autopsied brain samples taken from
patients with schizophrenia (SCH) and mentally healthy subjects (23 and 22 cases, respectively). These biochemical parameters
were measured in tissue extracts in three brain areas (prefrontal cortex, caudate nucleus, and cerebellum). Significant differences
in the level of at least one of the glutamate metabolizing enzymes were observed between two studied groups in all studied
brain areas. Different patterns of correlative links between the biochemical parameters were found in healthy and schizophrenic
brains. These findings give a new perspective to our understanding of the impaired regulation of enzyme levels in the brain
in SCH. 相似文献
90.
Ileana Manduteanu Dan Simionescu Agneta Simionescu Maya Simionescu 《Journal of cellular and molecular medicine》2021,25(20):9483-9495
Valve disease and particularly calcific aortic valve disease (CAVD) and diabetes (DM) are progressive diseases constituting a global health burden for all aging societies (Progress in Cardiovascular Diseases. 2014;56(6):565: Circulation Research. 2021;128(9):1344). Compared to non-diabetic individuals (The Lancet. 2008;371(9626):1800: The American Journal of Cardiology. 1983;51(3):403: Journal of the American College of Cardiology. 2017;69(12):1523), the diabetic patients have a significantly greater propensity for cardiovascular disorders and faster degeneration of implanted bioprosthetic aortic valves. Previously, using an original experimental model, the diabetic-hyperlipemic hamsters, we have shown that the earliest alterations induced by these conditions occur at the level of the aortic valves and, with time these changes lead to calcifications and CAVD. However, there are no pharmacological treatments available to reverse or retard the progression of aortic valve disease in diabetes, despite the significant advances in the field. Therefore, it is critical to uncover the mechanisms of valve disease progression, find biomarkers for diagnosis and new targets for therapies. This review aims at presenting an update on the basic research in CAVD in the context of diabetes. We provide an insight into the accumulated data including our results on diabetes-induced progressive cell and molecular alterations in the aortic valve, new potential biomarkers to assess the evolution and therapy of the disease, advancement in targeted nanotherapies, tissue engineering and the potential use of circulating endothelial progenitor cells in CAVD. 相似文献