全文获取类型
收费全文 | 614篇 |
免费 | 82篇 |
专业分类
696篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 22篇 |
2020年 | 17篇 |
2019年 | 23篇 |
2018年 | 21篇 |
2017年 | 25篇 |
2016年 | 19篇 |
2015年 | 41篇 |
2014年 | 36篇 |
2013年 | 44篇 |
2012年 | 55篇 |
2011年 | 35篇 |
2010年 | 29篇 |
2009年 | 18篇 |
2008年 | 31篇 |
2007年 | 18篇 |
2006年 | 25篇 |
2005年 | 23篇 |
2004年 | 15篇 |
2003年 | 13篇 |
2002年 | 19篇 |
2001年 | 15篇 |
2000年 | 10篇 |
1999年 | 13篇 |
1998年 | 3篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 5篇 |
1993年 | 6篇 |
1992年 | 10篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1985年 | 3篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1976年 | 3篇 |
1974年 | 3篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1971年 | 3篇 |
1969年 | 6篇 |
1967年 | 6篇 |
1966年 | 2篇 |
1965年 | 2篇 |
排序方式: 共有696条查询结果,搜索用时 15 毫秒
681.
A system for an electrified enclosure designed for baboons is described. Live wires were alternated with grounded wires in order to increase the likelihood of electric shock if an animal tried to escape. A sinusoidal current of 50-Hz frequency, 650-V voltage, and 10 mA was used and proved to be quite efficient and not dangerous. In order to make the apparatus more reliable the electric main sources were connected to an automatic control system which monitored irregularities in the supply and switches to an emergency circuit if necessary. 相似文献
682.
Daniel C Hatton Qi Yue Justin Chapman Hong Xue Jacqueline Dierickx Chantal Roullet Sarah Coste Jean Baptiste Roullet David A McCarron 《Journal of applied physiology》2002,92(1):13-17
Ground studies indicate that spaceflight may diminish vascular contraction. To examine that possibility, vascular function was measured in spontaneously hypertensive rats immediately after an 18-day shuttle flight. Isolated mesenteric resistance arterial responses to cumulative additions of norepinephrine, acetylcholine, and sodium nitroprusside were measured using wire myography within 17 h of landing. After flight, maximal contraction to norepinephrine was attenuated (P < 0.001) as was relaxation to acetylcholine (P < 0.001) and sodium nitroprusside (P < 0.05). At high concentrations, acetylcholine caused vascular contraction in vessels from flight animals but not in vessels from vivarium control animals (P < 0.05). The results are consistent with data from ground studies and indicate that spaceflight causes both endothelial-dependent and endothelial-independent alterations in vascular function. The resulting decrement in vascular function may contribute to orthostatic intolerance after spaceflight. 相似文献
683.
684.
685.
Two endocrinologically active octapeptide analogues (BIM-23014 C and BIM-23034) of somatostatin (SRIF) containing either an N- or C-terminal 3-(2-naphthyl)-D-Ala residue were examined for their ability to inhibit the in vitro receptor binding, clonal growth, and vasoactive intestinal peptide (VIP)-stimulated cyclic AMP formation in human small cell lung cancer cell (SCLC) line NCI-H345. Both SRIF peptides inhibited [125I]SRIF(Tyr11)-14 binding with IC50 values in the low nM range. Colony formation in the in vitro SCLC growth assay was also inhibited in the same concentration range, as was VIP-stimulated cyclic AMP formation. Therefore, octapeptide analogues of SRIF function as SCLC SRIF receptor agonists. 相似文献
686.
687.
Summary In Saccharomyces cerevisiae, three different DNA polymerase complexes, POLI, POLII and POLIII, are known to be involved in DNA replication. The catalytic subunit of POLIII is encoded by the essential CDC2 gene. The existence of different thermosensitive non-complementing mutants of CDC2 offers the possibility of using a genetic approach to investigate the involvement of POLIII in induced gene conversion. When cdc2 heteroallelic cells were irradiated and incubated under restrictive conditions, almost no induction of thermoresistant cells could be detected, suggesting an essential role for POLIII in mitotic gene conversion events. 相似文献
688.
J F Ygout G Fabre F Leterrier P Cazin J Saint-Blancard 《Revue fran?aise de transfusion et immuno-hématologie》1983,26(3):253-265
Apparent stationary viscosity, viscoelasticity and thixotropy measured with a Couette viscosimeter have been determined on blood samples stored in eight anticoagulant and/or preservative solutions. All the results as well as those obtained in a previous morphological study show clearly the advantages of the SAG or PAGGS storage processes. It is observed that the rheological parameters of RBC stored in protein poor media are, between the 30 th and 35 th days, identical on CPD at the first week and with that measured in CPD concentrates between second and third week (for a same hematocrit value). We want to emphasize that the erythrocytes stored in these new media retain for a long time their ability to circulate in the capillary system. 相似文献
689.
J Lecompte M Angue J P Baechle Y Neveux Y Clerc G Fabre M Joussemet 《Revue fran?aise de transfusion et immuno-hématologie》1985,28(1):69-89
We report the comparison of the fonctionnal platelet criteria's evolution studied in vitro by aggregation with different agents, by osmotic stress, ATP total amount and platelet volume distribution for six days of storage in two different PVC bags. The results indicate that: platelet's evolution appears more appreciable when tested by aggregation with an important amount of collagen, by hypotonic stress and volume distribution. The difference between the two different bags is shown as early as the thirs day of storage; for quality control, we can choose some criteria despite the absence of their clear correlation with transfusion efficiency. 相似文献
690.
Jacqueline Gunther Baptiste Jayet Adam Jacobs Ray Burke Jana M. Kainerstorfer Stefan Andersson-Engels 《Journal of biophotonics》2021,14(9):e202000486
About a third of babies are delivered by Cesarean section. There has been an increase in maternal deaths during labor due to complications with subsequent births after a C-section. Therefore, there is a clinical motivation to reduce the C-section rate. Current techniques are, however, inefficient at determining fetal distress leading to a high false positive rate for complications and ultimately a C-section. For the current study, Monte Carlo simulations were used to calculate the amount of signal received on a model of a pregnant mother, as well as, the percent of the signal that comes from the fetal layer. Models with and without a 1 mm amniotic fluid were compared and showed differing trends. 相似文献