全文获取类型
收费全文 | 7343篇 |
免费 | 563篇 |
国内免费 | 3篇 |
出版年
2023年 | 29篇 |
2022年 | 60篇 |
2021年 | 119篇 |
2020年 | 75篇 |
2019年 | 71篇 |
2018年 | 115篇 |
2017年 | 92篇 |
2016年 | 171篇 |
2015年 | 277篇 |
2014年 | 338篇 |
2013年 | 472篇 |
2012年 | 583篇 |
2011年 | 556篇 |
2010年 | 363篇 |
2009年 | 345篇 |
2008年 | 446篇 |
2007年 | 480篇 |
2006年 | 483篇 |
2005年 | 464篇 |
2004年 | 415篇 |
2003年 | 450篇 |
2002年 | 424篇 |
2001年 | 83篇 |
2000年 | 62篇 |
1999年 | 74篇 |
1998年 | 84篇 |
1997年 | 62篇 |
1996年 | 66篇 |
1995年 | 54篇 |
1994年 | 52篇 |
1993年 | 46篇 |
1992年 | 48篇 |
1991年 | 34篇 |
1990年 | 31篇 |
1989年 | 27篇 |
1988年 | 17篇 |
1987年 | 20篇 |
1986年 | 23篇 |
1985年 | 31篇 |
1984年 | 25篇 |
1983年 | 22篇 |
1982年 | 20篇 |
1981年 | 16篇 |
1980年 | 12篇 |
1979年 | 16篇 |
1977年 | 13篇 |
1976年 | 12篇 |
1974年 | 13篇 |
1973年 | 18篇 |
1969年 | 13篇 |
排序方式: 共有7909条查询结果,搜索用时 15 毫秒
31.
A Gyévai G Horváth E Bartha 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》1988,26(2):61-70
Studies have been performed on the relationship between PRL and GH production and the 45Ca2+ influx in high magnesium content in vitro. The obtained data show that an elevated magnesium concentration in Krebs-Ringer solution is capable of inhibiting some hormonal function of the pituitary gland. It has been found, that PRL and GH released into the media in normal KRB solution revealed nearly two times higher concentration than in the presence of high Mg2+. Instead the cellular iPRL and iGH did not show any significant differences in control and in treated cultures. The incorporation of 4.5-3H-leucine into the prolactin and growth hormone demonstrate a significant decrease in the presence of high Mg2+ indicating that the ion is able to inhibit the secretion of newly synthesized PRL an GH. High concentration of Mg2+ abolished either the stimulation effect of releasing hormones on calcium uptake. 相似文献
32.
33.
Mária Zsófia Koltai Peter Rösen Pál Hadházy Zoltán Aranyi György Ballagi-Pordány Gábor Pogátsa 《Molecular and cellular biochemistry》1992,109(2):189-196
The aim of this study was to clarify whether or not arachidonic acid metabolic disorders are caused by a substrate inavailability and whether such disorders might contribute to circulatory disturbances in the diabetic myocardium. Norepinephrine induced a decrease in the conductivity of both coronary arterial bed and myocardial microcirculation in alloxan-diabetic dogs. It was markedly (p < 0.05) attenuated both by indomethacin and acetylsalicylic acid pretreatments indicating an imbalance among the vasoactive prostanoids in diabetes. TXA2 release from the diabetic coronary rings was found to be elevated and could be normalized after the blockade of vascular adrenoceptors by phentolamine (p < 0.05). PGIZ synthesis was also enhanced by adrenergic blockade in the diabetic arterial rings. After pretreatment with l4C arachidonic acid, in order to measure substrate availability, the arachidonic acid metabolic rate was less in the diabetic coronary arteries than in healthy vessels (p < 0.05). Ten µmol/1 norepinephrine decreased arachidonic acid metabolism in the presence of prelabelled substrate in the diabetic animals, compared to an increase observed in metabolically healthy dogs. Therefore diabetes appears to diminish arachidonic acid metabolism and uptake independent of adrenoceptors and to induce an imbalance between vasoconstrictor and vasodilator cyclooxygenase products, resulting in elevated TXA2 release controlled by adrenergic mechanisms which may contribute to an impairment in myocardial microcirculation.Abbreviations 6-oxo-PGF1
6-oxo prostaglandin F1
- HPLC
High Pressure Liquid Chromatograph
- LAD
Left Anterior Descending (coronary artery)
- PGI2
Prostacyclin
- TXA2
Thromboxane 相似文献
34.
35.
Mapping of genes on the linear chromosome of the bacterium Borrelia burgdorferi: Possible locations for its origin of replication 总被引:13,自引:0,他引:13
Iain G. Old Jane MacDougall Isabelle Saint Girons Barrie E. Davidson 《FEMS microbiology letters》1992,99(2-3):245-250
Molecular clones of Borrelia burgdorferi, aetiologic agent of Lyme borreliosis, were isolated and analysed by DNA sequence determination. This procedure yielded B. burgdorferi homologues of gidA, gyrB, gyrA, ftsA and ftsZ. The genes were located on the physical map of the B. burgdorferi linear chromosome. Also mapped were the genes fla and p60 while dnaA was mapped using a heterologous probe. gyrA and gyrB were found to be in tandem and were mapped, along with dnaA at the centre of the chromosome. gidA was located close to the left hand extremity of the chromosome. Because gyrB, dnaA and gidA are normally located within 50 kb of the origin of replication (oriC), we propose two possible sites for oriC in the B. burgdorferi linear chromosome. 相似文献
36.
37.
38.
39.
Elisabetta Zappone Isabelle Dugast Panos Papadopoulos Kelly Theriault Veronique David Jean-Yves LeGall Kim Summers Lawrie Powell Jim Drysdale 《Human genetics》1991,86(6):557-561
Summary This paper addresses the question of whether abnormalities in ferritin expression in the iron storage disease hemochromatosis (HC) involve major deletions or alterations in regions containing the two ferritin H genes that lie near the disease locus on chromosome 6p. We present evidence from analyses of Southern blots that neither gene is deleted in hemochromatosis. We also describe a polymorphism in one of the genes that we have previously shown to be a processed pseudogene. This polymorphism does not correlate with the presence of HC. The PIC value for this polymorphism was calculated as 0.49. 相似文献
40.
Eveline De Mdicis Jean Paquette Jean-Jacques Gauthier Dennis Shapcott 《Applied microbiology》1986,52(3):567-573
Magnesium and manganese contents were measured by atomic absorption spectrophotometry in bacteria of several halophilic levels, in Vibrio costicola, a moderately halophilic eubacterium growing in 1 M NaCl, Halobacterium volcanii, a halophilic archaebacterium growing in 2.5 M NaCl, Halobacterium cutirubrum, an extremely halophilic archaebacterium growing in 4 M NaCl, and Escherichia coli, a nonhalophilic eubacterium growing in 0.17 M NaCl. Magnesium and manganese contents varied with the growth phase, being maximal at the early log phase. Magnesium and manganese molalities in cell water were shown to increase with the halophilic character of the logarithmically growing bacteria, from 30 mmol of Mg per kg of cell water and 0.37 mmol of Mn per kg of cell water for E. coli to 102 mmol of Mg per kg of cell water and 1.6 mmol of Mn per kg of cell water for H. cutirubrum. The intracellular concentrations of manganese were determined independently by a radioactive tracer technique in V. costicola and H. volcanii. The values obtained by 54Mn loading represented about 70% of the values obtained by atomic absorption. The increase of magnesium and manganese contents associated with the halophilic character of the bacteria suggests that manganese and magnesium play a role in haloadaptation. 相似文献