全文获取类型
收费全文 | 83750篇 |
免费 | 6563篇 |
国内免费 | 6022篇 |
出版年
2023年 | 1204篇 |
2022年 | 1235篇 |
2021年 | 2177篇 |
2020年 | 2629篇 |
2019年 | 3473篇 |
2018年 | 2930篇 |
2017年 | 2310篇 |
2016年 | 2299篇 |
2015年 | 2681篇 |
2014年 | 4484篇 |
2013年 | 5751篇 |
2012年 | 3726篇 |
2011年 | 4549篇 |
2010年 | 3626篇 |
2009年 | 4215篇 |
2008年 | 4569篇 |
2007年 | 4606篇 |
2006年 | 4270篇 |
2005年 | 3929篇 |
2004年 | 3554篇 |
2003年 | 3157篇 |
2002年 | 2807篇 |
2001年 | 2102篇 |
2000年 | 1738篇 |
1999年 | 1663篇 |
1998年 | 1380篇 |
1997年 | 1186篇 |
1996年 | 1140篇 |
1995年 | 1243篇 |
1994年 | 1209篇 |
1993年 | 906篇 |
1992年 | 846篇 |
1991年 | 722篇 |
1990年 | 566篇 |
1989年 | 497篇 |
1988年 | 448篇 |
1987年 | 442篇 |
1986年 | 354篇 |
1985年 | 552篇 |
1984年 | 828篇 |
1983年 | 636篇 |
1982年 | 663篇 |
1981年 | 508篇 |
1980年 | 481篇 |
1979年 | 393篇 |
1978年 | 301篇 |
1977年 | 275篇 |
1976年 | 270篇 |
1975年 | 223篇 |
1973年 | 195篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
3.
4.
5.
6.
L. Crispoltoni S. Porcellati A. M. Del Pino A. Orlacchio G. Coata S. Arnone E. Torlone B. Cappuccini G. C. Di Renzo A. Orlacchio 《Cell biochemistry and function》2014,32(1):87-95
Several epidemiological studies showed that gestational diabetes mellitus is the most frequent metabolic disorder of pregnancy, the pathogenesis of which has yet to be completely clarified. The aim of this study was to investigate the presence and processing of caspase 3 (Casp3) and poly(ADP‐ribose) polymerase 1 (PARP1) in cord blood lymphocytes as markers of apoptosis in relation to glycaemic control during intrauterine life. Our results showed a specific positive correlation between the levels of active Casp3 (17–19 kDa) and the inactive form of PARP1 (89 kDa) in lymphocytes isolated from newborn babies of diabetic women with unbalanced glycaemic control, with a direct correlation between the activation of casp3 and the inactivation of PARP1, that makes lymphocytes unresponsive towards lipopolysaccharide stimulation, highlighting an altered functional response. Besides more studies are required to fully correlate the activation of the apoptotic process during the intrauterine life with the foetal health later in life, our study indicates that a cord blood lymphocyte, an easily accessible source, is informative about the activation of apoptotic stimuli in circulating cells of newborn babies in relation to the glycaemic control reached by the mother during pregnancy. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
7.
In this article, we discuss molecular mechanisms involved in the evolution of amygdala kindling and the episodic loss of response
to pharmacological treatments during tolerance development. These phenomena allow us to consider how similar principles (in
different neurochemical systems) could account for illness progression, cyclicity, and drug tolerance in affective disorders.
We describe the phenomenon of amygdala-kindled seizures episodically breaking through effective daily pharmacotherapy with
carbamazepine and valproate, suggesting that these observations could reflect the balance of pathological vs compensatory
illness-induced changes in gene expression. Under certain circumstances, amygdala-kindled animals that were initially drug
responsive can develop highly individualized patterns of seizure breakthroughs progressing toward a complete loss of drug
efficacy. This initial drug efficacy may reflect the combination of drug-related exogenous neurochemical mechanisms and illness-induced
endogenous compensatory mechanisms. However, we postulate that when seizures are inhibited, the endogenous illness-induced
adaptations dissipate (the “time-off seizure” effect), leading to the re-emergence of seizures, a re-induction of a new, but
diminished, set of endogenous compensatory mechanisms, and a temporary period of renewed drug efficacy. As this pattern repeats,
an intermittent or cyclic response to the anticonvulsant treatment emerges, leading toward complete drug tolerance.
We also postulate that the cyclic pattern accelerates over time because of both the failure of robust illness-induced endogenous
adaptations to emerge and the progression in pathophysiological mechanisms (mediated by long-lasting changes in gene expression
and their downstream consequences) as a result of repeated occurrences of seizures. In this seizure model, this pattern can
be inhibited and drug responsivity can be temporarily reinstated by several manipulations, including lowering illness drive
(decreasing the stimulation current.), increasing drug dosage, switching to a new drug that does not show crosstolerance to
the original medication, or temporarily discontinuing treatment, allowing the illness to re-emerge in an unmedicated animal.
Each of these variables is discussed in relation to the potential relevance to the emergence, progression, and suppression
of individual patterns of episodic cyclicity in the recurrent affective disorders. A variety of clinical studies are outlined
that specifically test the hypotheses derived from this formulation. Data from animal studies suggest that illness cyclicity
can develop from the relative ratio between primary pathological processes and secondary endogenous adaptations (assisted
by exogenous medications). If this proposition is verified, it further suggests that illness cyclicity is inherent to the
neurobiological processes of episode emergence and amelioration, and one does not need to postulate a separate defect in the
biological clock. The formulation predicts that early and aggressive long-term interventions may be optimal in order to prevent
illness emergence and progression and its associated accumulating neurobiological, vulnerability factors. 相似文献
8.
Protein secretion in streptomycetes 总被引:1,自引:0,他引:1
9.
The actin cortex is a thin layer of actin, myosin and actin-binding proteins that underlies the membrane of most animal cells. It is highly dynamic and can undergo remodelling on timescales of tens of seconds, thanks to protein turnover and myosin-mediated contractions. The cortex enables cells to resist external mechanical stresses, controls cell shape and allows cells to exert forces on their neighbours. Thus, its mechanical properties are the key to its physiological function. Here, we give an overview of how cortex composition, structure and dynamics control cortex mechanics and cell shape. We use mitosis as an example to illustrate how global and local regulation of cortex mechanics gives rise to a complex series of cell shape changes. 相似文献
10.