全文获取类型
收费全文 | 792篇 |
免费 | 36篇 |
出版年
2023年 | 4篇 |
2022年 | 5篇 |
2021年 | 9篇 |
2020年 | 7篇 |
2019年 | 4篇 |
2018年 | 17篇 |
2017年 | 12篇 |
2016年 | 24篇 |
2015年 | 27篇 |
2014年 | 28篇 |
2013年 | 50篇 |
2012年 | 38篇 |
2011年 | 69篇 |
2010年 | 34篇 |
2009年 | 31篇 |
2008年 | 47篇 |
2007年 | 53篇 |
2006年 | 48篇 |
2005年 | 49篇 |
2004年 | 39篇 |
2003年 | 45篇 |
2002年 | 42篇 |
2001年 | 5篇 |
2000年 | 12篇 |
1999年 | 7篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 5篇 |
1993年 | 10篇 |
1992年 | 6篇 |
1991年 | 13篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1975年 | 4篇 |
1966年 | 1篇 |
排序方式: 共有828条查询结果,搜索用时 218 毫秒
61.
62.
Violetta Skrzypulec-Plinta Agnieszka Drosdzol Krzysztof Nowosielski Ryszard Plinta 《Reproductive biology and endocrinology : RB&E》2010,8(1):141
Background
Premenstrual dysphoric disorder has multiple determinants in the biological, psychological and socio-cultural domains. The aim of the study was to evaluate the risk factors for premenstrual dysphoric disorder in Polish women, considering their reproductive history, socio-economic factors, as well as lifestyle and health-related factors. 相似文献63.
64.
Kubiński K Domańska K Sajnaga E Mazur E Zieliński R Szyszka R 《Molecular and cellular biochemistry》2007,295(1-2):229-236
Protein kinase CK2 is a highly conserved Ser/Thr protein kinase that is ubiquitous among eucaryotic organisms and appears
to play an important role in many cellular functions. This enzyme in yeast has a tetrameric structure composed of two catalytic
(α and/or α′) subunits and two regulatory β and β′ subunits. Previously, we have reported isolation from yeast cells four
active forms of CK2, composed of αα′ββ′, α2ββ′, α′2ββ′ and a free α′-catalytic subunit. Now, we report that in Saccharomyces cerevisiae CK2 holoenzyme regulatory β subunit cannot substitute other β′ subunit and only both of them can form fully active enzymatic
unit. We have examined the subunit composition of tetrameric complexes of yeast CK2 by transformation of yeast strains containing
single deletion of the β or β′ regulatory subunits with vectors carrying lacking CKB1 or CKB2 genes. CK2 holoenzyme activity was restored only in cases when both of them were present in the cell. Additional, co-immunoprecypitation
experiments show that polyadenylation factor Fip1 interacts with catalytic α subunits of CK2 and interaction with beta subunits
in the holoenzyme decreases CK2 activity towards this protein substrate. These data may help to elucidate the role of yeast
protein kinase CK2β/β′ subunits in the regulation of holoenzyme assembly and phosphotransferase activity. 相似文献
65.
Chemosensory proteins in the honey bee: Insights from the annotated genome, comparative analyses and expressional profiling 总被引:5,自引:0,他引:5
Small chemosensory proteins (CSPs) belong to a conserved, but poorly understood protein family that has been implicated in transporting chemical stimuli within insect sensilla. However, their expression patterns suggest that these molecules are also critical for other functions including early development. Here we used both bioinformatics and experimental approaches to characterize the CSP gene family in a social insect, the Western honey bee Apis mellifera, and then compared its members to CSPs in other arthropods. The number of CSPs in the honey bee genome (six) is similar to that found in the sequenced dipteran species (four-seven), but is much lower than the number of CSPs in the moth or in the beetle (around 20 each). These differences seem to be the result of lineage specific expansions. Our analysis of CSPs in a number of arthropods reveals a conserved gene family found in both Mandibulates and Chelicerates. Expressional profiling in diverse tissues and throughout development reveals broader than expected patterns of expression with none of the CSPs restricted to the antennae and one found only in the queen ovaries and in embryos. We conclude that CSPs are multifunctional context-dependent proteins involved in diverse cellular processes ranging from embryonic development to chemosensory signal transduction. Some CSPs may function in cuticle synthesis, consistent with their evolutionary origins in the arthropods. 相似文献
66.
Paluchowska MH Bugno R Duszyńska B Tatarczyńska E Nikiforuk A Lenda T Chojnacka-Wójcik E 《Bioorganic & medicinal chemistry》2007,15(22):7116-7125
New, flexible (7, 9, 11 and 13) and rigid (8, 10, 12 and 14) imides with a 1-(m-trifluorophenyl)piperazine fragment and a tetramethylene or a 1e,4e-cyclohexylene spacer, respectively, showed very high affinity (K(i)=0.3-34 nM) and agonistic in vivo activity for 5-HT(1A) receptors. Flexible new compounds and the previously described 5 also bound to 5-HT(7) receptors (K(i)=21-134 nM). Selected glutarimide derivatives, that is, the most potent postsynaptic 5-HT(1A) receptor agonist rigid compound 8 and its flexible analogue 7, as well as the previously described full agonist-rigid compound 6 and the partial agonist-its flexible counterpart 5 exhibited moderate affinity for alpha(1)-adrenoceptors (K(i)=85 - 268 nM), but were practically devoid of any affinity for dopamine D(2) sites. Those glutarimides demonstrated anxiolytic- (5 and 7) and antidepressant-like (5, 6 and 8) activity in the four-plate and the swim tests in mice, respectively; at the same time, however, they inhibited the locomotor activity of mice. The antidepressant-like effect of 8 was significantly stronger than that induced by imipramine used as a reference antidepressant. 相似文献
67.
68.
To determine the effect of prenatal lead exposure on brain monoaminergic systems, pregnant rats were given tap water containing
250 ppm lead acetate, for the duration of pregnancy, while tap water without lead (Pb2+) was substituted at birth. Control rats were derived from dams that consumed tap water during pregnancy, and had no exposure
to lead afterwards. At 12 weeks after birth, Pb2+ content of brain cortex was increased 3- to 4-fold (P < 0.05). At this time the endogenous striatal levels of 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid were
19% lower in Pb2+ exposed rats (P < 0.05), while there was no change in the striatal level of dopamine (DA), noradrenaline, 3,4-dihydroxyphenylglycol, serotonin
(5-HT) and 5-hydroxyindoleacetic acid (HPLC/ED). Also there was no change in these monoamines and metabolites in the prefrontal
cortex of Pb2+ exposed rats. However, turnover of 5-HT in prefrontal cortex, as indicated by 5-hydroxytryptophan accumulation 30 min after
acute treatment with the decarboxylase inhibitor NSD-1015 (100 mg/kg IP), was lower in the Pb2+ exposed rats. In the striatum AMPH-induced (1 mg/kg IP) turnover of DA, evidenced as L-DOPA accumulation after NSD-1015,
was increased to a lesser extent in the Pb2+ exposed rats (P < 0.05). The nitric oxide synthase inhibitor 7-nitroindazole (10 mg/kg IP) attenuated the latter effect, indicating that
neuronal NO mediates this AMPH effect, at least in part. Moreover, DA D2 receptor sensitivity developed in Pb2+ exposed rats, as evidenced by enhanced quinpirole-induced yawning activity and enhanced quinpirole-induced locomotor activity
(each, P < 0.05). These findings indicate that ontogenetic exposure to lead can have consequences on monoaminergic neuronal function
at an adult stage of life, generally promoting accentuated behavioral effects of direct and indirect monoaminergic agonists,
and related to increased dopamine turnover in basal ganglia.
Special issue dedicated to Dr. Moussa Youdim. 相似文献
69.
Czerwińska E Marcinowska-Suchowierska E Walicka M Lisik W Wierzbicki Z 《Endokrynologia Polska》2007,58(2):130-138
INTRODUCTION: Obese patients may have abnormal calcium homeostasis because of unbalanced diet and decreased sun exposure. Bariatric surgery itself may lead to disturbances in calcium homeostasis (and in consequence changes in bone mass) or increase preexisting metabolic derangements. The aim of the study was: 1. To assess calcium homeostasis and biochemical markers of bone turnover in patients with morbid obesity. 2. To determine the impact of bariatric surgery on parameters mentioned above. 3. To establish recommendations for supplementation with calcium and vitamin D in morbidly obese patients after bariatric surgery. MATERIAL AND METHODS: Serum calcium, parathormone (PTH), vitamin D (25(OH)D), biochemical markers of bone turnover (beta-CrossLaps as a marker of bone resorption and osteocalcin as a marker of bone formation) and urine calcium as well as fat mass, lean mass and bone mineral content (by DXA) were measured before bariatric surgery of the stomach (VBG or GBP) in 57 morbidly obese patients (48 women, 9 men; mean age 35.9 y). The same procedures were repeated six months after operation in 28 of them (24 women, 4 men). Daily calcium intake was also determined based on food questionnaire. RESULTS: Biochemical findings in the group of patients before bariatric surgery were as follows: serum calcium, beta-CrossLaps and urine calcium were within normal range, PTH concentration was increased to 81.0 pg/ml and 25(OH)D as well as osteocalcin concentration decreased (4.9 ng/ml and 13.6 ng/ml, respectively). Six months after bariatric surgery there was no change in serum and urine calcium, PTH concentration decreased to normal level (46.8 pg/ml), 25(OH)D concentration increased to 6.5 ng/ml (not significant) and still remained below normal range. Markers of bone turnover--both resorption and formation--increased (beta-CrossLaps over normal range to 0.594 ng/ml, osteocalcin to normal range 26.8 ng/ml). Daily calcium intake was below RDA before and after bariatric procedure. CONCLUSIONS: 1. Patients with morbid obesity have secondary hyperparathyroidism and deficiency of vitamin D. 2. Abrupt weight loss after bariatric surgery is accompanied by the regression of secondary hyperparathyroidism, decrease of the deficiency of vitamin D and increase in bone turnover. 3. Supplementation with vitamin D and calcium is recommended for patients with morbid obesity after bariatric surgery. 相似文献
70.
Angel R Barchuk Alexandre S Cristino Robert Kucharski Luciano F Costa Zilá LP Simões Ryszard Maleszka 《BMC developmental biology》2007,7(1):70