全文获取类型
收费全文 | 84629篇 |
免费 | 4951篇 |
国内免费 | 14篇 |
出版年
2023年 | 483篇 |
2021年 | 1051篇 |
2020年 | 909篇 |
2019年 | 886篇 |
2018年 | 2267篇 |
2017年 | 2001篇 |
2016年 | 2746篇 |
2015年 | 3632篇 |
2014年 | 3725篇 |
2013年 | 4862篇 |
2012年 | 5743篇 |
2011年 | 5043篇 |
2010年 | 3302篇 |
2009年 | 2456篇 |
2008年 | 4087篇 |
2007年 | 3844篇 |
2006年 | 3823篇 |
2005年 | 3211篇 |
2004年 | 3179篇 |
2003年 | 2853篇 |
2002年 | 2602篇 |
2001年 | 2063篇 |
2000年 | 1915篇 |
1999年 | 1485篇 |
1998年 | 664篇 |
1996年 | 533篇 |
1995年 | 482篇 |
1992年 | 929篇 |
1991年 | 856篇 |
1990年 | 832篇 |
1989年 | 905篇 |
1988年 | 749篇 |
1987年 | 760篇 |
1986年 | 705篇 |
1985年 | 766篇 |
1984年 | 643篇 |
1983年 | 552篇 |
1982年 | 473篇 |
1979年 | 677篇 |
1978年 | 505篇 |
1977年 | 507篇 |
1975年 | 591篇 |
1974年 | 641篇 |
1973年 | 608篇 |
1972年 | 555篇 |
1971年 | 504篇 |
1970年 | 544篇 |
1969年 | 619篇 |
1968年 | 580篇 |
1967年 | 487篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
A Sólyom S Tóth I Holczinger J Vajda Z Tóth R Kálmánchey 《Applied neurophysiology》1985,48(1-6):222-225
Four thalamic and cortical recordings were carried out in 5 patients. The thalamic-evoked potentials were typical and revealed a triphasic complex, but their latencies showed a relatively high standard deviation. They could be divided into two groups according to their latencies, both of which had low SD. These data suggested that there could be two types of latency of thalamic SEP, because the 4 patients' body sizes were very similar. More detailed surface, cortical and depth recordings are needed to resolve these questions. 相似文献
52.
53.
Michael D. Jensen Ji?í Bajnárek Sang Yeoup Lee Soren Nielsen Christina Koutsari 《Journal of lipid research》2009,50(9):1863-1869
The relationship between overnight postabsorptive (fasting) respiratory exchange ratio (RER) and plasma FFA concentrations was addressed using data from three separate protocols, each of which involved careful control of the antecedent diet. Protocol 1 examined the relationship between fasting RER and the previous daytime RER. In Protocol 2 fasting, RER and plasma palmitate concentrations were measured in 29 women and 31 men (body mass index <30 kg·m−2). Protocol 3 analyzed data from Nielsen et al. (Nielsen, S., Z. K. Guo, J. B. Albu, S. Klein, P. C. O''Brien, M. D. Jensen. 2003. Energy expenditure, sex and endogenous fuel availability in humans. J. Clin. Invest. 111: 981-988.) to understand how fasting RER and palmitate concentrations relate within individuals during four consecutive measurements. The results were as follows: 1) Fasting RER was correlated (r = 0.74, P < 0.001) with the previous day''s average RER, and less so with RER variability. 2) Fasting RER was correlated (r = −0.39, P = 0.007) with fasting plasma palmitate concentrations. 3) The pattern of the RER/palmitate relationship was similar within individuals and between individuals; a negative slope was observed significantly more often than a positive slope (χ2 test; P < 0.001). Our findings suggest that, despite a fixed food quotient, the slight departures from energy equilibrium in a controlled General Clinical Research Center environment can effect plasma FFA concentrations. We suggest that including indirect calorimetry as part of FFA metabolism studies may aid in data interpretation. 相似文献
54.
55.
Effect of precursors on biosynthesis of monensins A and B 总被引:1,自引:0,他引:1
Precursors of monensins (acetate, propionate, butyrate, isobutyrate) affect the total production and the relative proportion of monensins A and B. Addition of propionate into the fermentation medium causes a prevalence of monensin B whereas butyrate and isobutyrate stimulate the production of monensin A and suppress the production of monensin B. 相似文献
56.
M Lebl E E Sugg G van Binst P Vander Elst D Tourwé J Slaninová V J Hruby 《International journal of peptide and protein research》1987,30(3):318-322
Analogs of deamino-oxytocin and deamino-oxypressin containing a CH2-NH group instead of an amide bond between positions 8 and 9 were synthesized. All tested compounds exhibit significantly lowered biological activities. 相似文献
57.
H. Štorchová 《Biologia Plantarum》1994,36(3):358-358
58.
59.
Jens Blechert Eva Naumann Julian Schmitz Beate M. Herbert Brunna Tuschen-Caffier 《PloS one》2014,9(1)
Many individuals restrict their food intake to prevent weight gain. This restriction has both homeostatic and hedonic effects but their relative contribution is currently unclear. To isolate hedonic effects of food restriction, we exposed regular chocolate eaters to one week of chocolate deprivation but otherwise regular eating. Before and after this hedonic deprivation, participants viewed images of chocolate and images of high-calorie but non-chocolate containing foods, while experiential, behavioral and eyeblink startle responses were measured. Compared to satiety, hedonic deprivation triggered increased chocolate wanting, liking, and chocolate consumption but also feelings of frustration and startle potentiation during the intertrial intervals. Deprivation was further characterized by startle inhibition during both chocolate and food images relative to the intertrial intervals. Individuals who responded with frustration to the manipulation and those who scored high on a questionnaire of impulsivity showed more relative startle inhibition. The results reveal the profound effects of hedonic deprivation on experiential, behavioral and attentional/appetitive response systems and underscore the role of individual differences and state variables for startle modulation. Implications for dieting research and practice as well as for eating and weight disorders are discussed. 相似文献
60.
Effect of pharmacological agents on the activity of the circular and longitudinal smooth muscle layers of human fallopian tube ampullar segments 总被引:1,自引:0,他引:1
The in vitro determination of the effects of some pharmacological agents on the outer diameter and axial tension of human Fallopian tube ampullar segments showed that some drugs may act on the circular and longitudinal smooth muscle layers relatively separately. PGF2 alpha elicited an excitatory response in both muscle layers while norepinephrine and isoproterenol decreased the activity. Oxytocin and indomethacin had relatively limited effects on the spontaneous motility of the ampullar segments. The calcium antagonist verapamil inhibited the spontaneous periodic activity. 相似文献