全文获取类型
收费全文 | 1584篇 |
免费 | 134篇 |
国内免费 | 2篇 |
专业分类
1720篇 |
出版年
2023年 | 4篇 |
2022年 | 8篇 |
2021年 | 21篇 |
2020年 | 13篇 |
2019年 | 13篇 |
2018年 | 17篇 |
2017年 | 29篇 |
2016年 | 36篇 |
2015年 | 66篇 |
2014年 | 69篇 |
2013年 | 90篇 |
2012年 | 107篇 |
2011年 | 104篇 |
2010年 | 67篇 |
2009年 | 69篇 |
2008年 | 72篇 |
2007年 | 91篇 |
2006年 | 93篇 |
2005年 | 93篇 |
2004年 | 71篇 |
2003年 | 85篇 |
2002年 | 74篇 |
2001年 | 23篇 |
2000年 | 22篇 |
1999年 | 24篇 |
1998年 | 30篇 |
1997年 | 16篇 |
1996年 | 19篇 |
1995年 | 24篇 |
1994年 | 25篇 |
1993年 | 24篇 |
1992年 | 22篇 |
1991年 | 15篇 |
1990年 | 17篇 |
1989年 | 26篇 |
1988年 | 10篇 |
1987年 | 13篇 |
1986年 | 21篇 |
1985年 | 13篇 |
1984年 | 13篇 |
1983年 | 11篇 |
1982年 | 4篇 |
1981年 | 7篇 |
1980年 | 8篇 |
1979年 | 7篇 |
1978年 | 11篇 |
1977年 | 10篇 |
1976年 | 4篇 |
1974年 | 3篇 |
1970年 | 3篇 |
排序方式: 共有1720条查询结果,搜索用时 15 毫秒
1.
Herman van der Kooij Ron Jacobs Bart Koopman Henk Grootenboer 《Biological cybernetics》1999,80(5):299-308
A model is presented to study and quantify the contribution of all available sensory information to human standing based
on optimal estimation theory. In the model, delayed sensory information is integrated in such a way that a best estimate of
body orientation is obtained. The model approach agrees with the present theory of the goal of human balance control. The
model is not based on purely inverted pendulum body dynamics, but rather on a three-link segment model of a standing human
on a movable support base. In addition, the model is non-linear and explicitly addresses the problem of multisensory integration
and neural time delays. A predictive element is included in the controller to compensate for time delays, necessary to maintain
erect body orientation. Model results of sensory perturbations on total body sway closely resemble experimental results. Despite
internal and external perturbations, the controller is able to stabilise the model of an inherently unstable standing human
with neural time delays of 100 ms. It is concluded, that the model is capable of studying and quantifying multisensory integration
in human stance control. We aim to apply the model in (1) the design and development of prostheses and orthoses and (2) the
diagnosis of neurological balance disorders.
Received: 25 August 1997 / Accepted in revised form: 8 December 1998 相似文献
2.
Protein kinase C phosphorylates the neurone-specific protein B-50 at a single Ser41 residue, which is also the point for a major proteolytic cleavage in vitro, and probably in vivo, that produces a B-50 phosphorylation-inhibiting N-terminal fragment and a large C-terminal metabolite B-60 (B-50(41-226]. The intact purified protein will bind to calmodulin in the absence of calcium, but the interaction has an absolute requirement for dephospho-B-50. In an attempt to unify two aspects of B-50 biochemistry, we have examined the interaction of B-50 binding to calmodulin and B-50 proteolysis. HPLC- and affinity-purified B-50 bound to calmodulin, but purified B-60 did not. To ensure that this effect was not due to the phosphorylation state of pure, isolated B-60, the metabolite was generated in vitro using a Triton extract of synaptosomal plasma membranes, which contains the as yet uncharacterized B-50 protease. B-60 derived from dephospho-B-50 also failed to bind calmodulin. The results demonstrate a direct connection between B-50 binding to calmodulin and B-50 proteolysis. The position of the proposed calmodulin-binding domain within intact B-50 is discussed in light of the failure of calmodulin to bind B-60. 相似文献
3.
Piet J. van den Hout Theunis Piersma Anne Dekinga Suzanne K. Lubbe G. Henk Visser 《Journal of avian biology》2006,37(5):425-430
To cope with changes in the environment, organisms not only show behavioural but also phenotypic adjustments. This is well established for the digestive tract. Here we present a first case of birds adjusting their flight machinery in response to predation risk. In an indoor experiment, ruddy turnstones Arenaria interpres were subjected to an unpredictable daily appearance of either a raptor or a small gull (as a control). Ruddy turnstones experiencing threat induced by a flying raptor model, longer than after similar passage by the gull model, refrained from feeding after this disturbance. Pectoral muscle mass, but not lean mass, responded in a course of a few days to changes in the perceived threat of predation. Pectoral muscle mass increased after raptor scares. Taking the small increases in body mass into account, pectoral muscle mass was 3.6% higher than aerodynamically predicted for constant flight performance. This demonstrates that perceived risk factors may directly affect organ size. 相似文献
4.
5.
6.
Henk van der Werff 《Brittonia》1995,47(4):372-375
Aiouea opaca andBeilschmiedia hexanthera, recently collected in central French Guiana, are described and illustrated. 相似文献
7.
Bacterial cells have three phases of growth which are characterized respectively by: (1) balanced growth with a high yield of biomass; (2) balanced growth with lower biomass yield; and (3) unbalanced growth with lowest biomass yield. Phases 2 and 3 are associated with elevated concentrations of the regulatory nucleotides centered on guanosine-5′-diphosphate-3′-diphosphate. Maintenance of the correct growth phase is important in optimizing industrial product formation by bacterial populations. 相似文献
8.
Hellema H 《BMJ (Clinical research ed.)》1991,302(6783):984-985
9.
Henk K. Mienis 《Journal of human evolution》2011,60(4):341-342
10.
Henk Gude Aart Beekman Paul H. B. Van't Padje Linus H. W. Van Der Plas 《Plant Growth Regulation》1988,7(2):101-116
Incubation of potato tuber tissue discs on B5 medium supplemented with 1-naphtyl-acetic acid (NAA) led to callus formation, irrespective of the presence of kinetin; without NAA no callus formation occurred. Incubation in the presence of abscisic acid (ABA) reduced the increases in fresh weight and dry weight both in callus-forming and in non-callus-forming tissue. Mitochondrial respiration was lowered by ABA as well. The induction of the alternative, CN-resistant pathway was inhibited by the presence of ABA, especially in mitochondria from non-callus-forming tissue.The in vivo respiration of the callus-forming tissue was higher than that of the non-callus-forming tissue. Total respiration, cytochrome pathway activity and the capacity of the alternative pathway were all lowered in callus-forming tissue by treatment with ABA. The in vivo activity of the alternative pathway was low in all tissue types, especially after ABA-treatment. The slight stimulation by hydroxamates of the oxygen uptake of callus-forming tissue incubated on medium with NAA and ABA indicates the involvement of a hydroxamate-activated peroxidase in the oxygen uptake of this tissue; this peroxidase seemed not to participate in the oxygen uptake of the other tissues types.In non-callus-forming tissue the oxygen uptake of ABA-treated tissue was very low and almost completely resistant to the combined addition of inhibitors of both the cytochrome and the alternative pathway, indicating that the in vivo activity of the mitochondria in the oxygen uptake of the tissue was very low. The possible causes for this ABA-effect are discussed. In non-callus-forming tissue the treatment with ABA creates a situation which is comparable with that observed in intact potato tubers. This situation is characterized by a tissue respiration lower than that of the isolated mitochondria and an alternative pathway capacity that is low or absent. 相似文献