全文获取类型
收费全文 | 4394篇 |
免费 | 315篇 |
国内免费 | 1篇 |
出版年
2022年 | 16篇 |
2021年 | 39篇 |
2020年 | 19篇 |
2019年 | 18篇 |
2018年 | 27篇 |
2017年 | 26篇 |
2016年 | 58篇 |
2015年 | 87篇 |
2014年 | 105篇 |
2013年 | 301篇 |
2012年 | 165篇 |
2011年 | 193篇 |
2010年 | 135篇 |
2009年 | 144篇 |
2008年 | 219篇 |
2007年 | 235篇 |
2006年 | 247篇 |
2005年 | 244篇 |
2004年 | 248篇 |
2003年 | 252篇 |
2002年 | 231篇 |
2001年 | 151篇 |
2000年 | 153篇 |
1999年 | 126篇 |
1998年 | 59篇 |
1997年 | 42篇 |
1996年 | 59篇 |
1995年 | 58篇 |
1994年 | 53篇 |
1993年 | 47篇 |
1992年 | 85篇 |
1991年 | 76篇 |
1990年 | 63篇 |
1989年 | 60篇 |
1988年 | 60篇 |
1987年 | 53篇 |
1986年 | 63篇 |
1985年 | 42篇 |
1984年 | 35篇 |
1983年 | 46篇 |
1982年 | 47篇 |
1981年 | 29篇 |
1980年 | 31篇 |
1979年 | 31篇 |
1978年 | 28篇 |
1977年 | 27篇 |
1976年 | 16篇 |
1975年 | 25篇 |
1974年 | 18篇 |
1969年 | 22篇 |
排序方式: 共有4710条查询结果,搜索用时 31 毫秒
61.
Kinetic aspects of the interaction of horse heart cytochrome c with sodium dodecyl sulfate 总被引:1,自引:0,他引:1
The sodium dodecyl sulfate (SDS) concentration dependence of spectral changes in circular dichroism (CD) and in absorbance of cytochrome c were examined in the far-ultraviolet region, aromatic region, and the Soret band. The Soret peak obtained in 0.60 mM SDS was nine times greater than that of the native state. (The critical micelle concentration, CMC, of SDS was 2.2 mM in the phosphate buffer used.) The results indicated that the drastic change at the Soret band did not accompany the corresponding large-scale change in secondary structure of the protein. In the stopped-flow measurements, two and three processes were followed at 406 nm below and above the CMC, respectively. At 289 nm only one process was observed, and this corresponded to the second process at 406 nm. Therefore, the second process at 406 nm was considered to be a change in tertiary structure around the heme group. The first process and the third process seemed to reflect a change in the heme environment; the former appeared to be due to a solvent effect and the latter due to a binding effect of a large number of dodecyl sulfate ions. 相似文献
62.
Central alpha-activation by clonidine reduces plasma level of beta-endorphin in patients with essential hypertension 总被引:1,自引:0,他引:1
K Yasunari Y Kanayama M Kohno K Murakawa T Kawarabayashi T Takeda N Kotsugai K Sato 《Life sciences》1985,37(16):1461-1467
Whether peripheral beta-endorphin contributes to the antihypertensive action of clonidine was examined by measuring plasma levels of beta-endorphin-like immunoreactivity (beta EpLI) after acute administration of clonidine in patients with essential hypertension. Administration of clonidine (0.225 mg) in one dose significantly lowered blood pressure, decreased heart rate and reduced the plasma level of beta EpLI and ACTH, while the placebo had no effect on blood pressure, heart rate or plasma level of beta EpLI suggesting that peripheral beta-endorphin does not play a major role in the antihypertensive action of acute clonidine administration. 相似文献
63.
Bile acid metabolism in partially hepatectomized rats 总被引:2,自引:0,他引:2
The bile flow and the bile acid secretion, calculated on liver weight basis, increased 12 H and 24 H after 60-70% hepatectomy and returned to the initial levels thereafter. The biliary phospholipid secretion much more increased than bile acids, but the cholesterol secretion decreased. Bile acid composition changed with an increase of the cholic acid group and a decrease of the chenodeoxycholic acid group in both bile and feces. These changes almost disappeared on Day 14. The pool size of bile acid decreased maximally on Day 4 to about 40% of the initial, but the distribution of bile acids in the enterohepatic circulation was not changed. The fecal cholesterol and coprostanol markedly decreased on Day 2 but gradually returned to the initial levels according to the recovery of diet intake. The fecal bile acids decreased on Day 2, increased on Day 4, and returned to the normal range after Day 7. In conclusion, the regenerating liver secretes more bile, bile acids and phospholipids, and less cholesterol than the normal liver. Cholic acid predominates in the bile acids. These changes restored to the initial levels by about one week after the operation. 相似文献
64.
65.
Tomoshiro Takeda Osamu Ueno Muneaki Samejima Takeshi Ohtani 《Journal of plant research》1985,98(4):393-411
Two hundred and twenty species of 38 genera in the Cyperaceae from Australia were examined for the possible occurrence of the C4 photosynthesis and the anatomical features of leaves and culms. The Kranz type of anatomy and the carbon isotope ratios typical of C4 plants were found in 84 species in the following six genera of four tribes belonging to subfamily Cyperoideae:Bulbostylis, Crosslandia, andFimbristylis (Fimbristylideae);Lipocarpha (Lipocarpheae);Cyperus (Cypereae);Rhynchospora (Rhynchosporeae). The anatomical observation revealed that the C4 species possessed any one of the three Kranz anatomical types found by previous investigators. It was suggested that in the Cyperaceae the C4 syndrome evolved independently within several taxa of the subfamily. The relative distribution of C3 and C4 species of the Cyperaceae in Australia was investigated by use of floristic data. It was recognized that the C4 species dominated in the northern part of the continent which was characterized by tropical and subtropical savannas and hot dry areas with summer rainfall, and the C3 species in the southern part, which contained temperate areas and mediterranean climatic areas with winter rainfall. 相似文献
66.
Akemichi Ueno Naokatu Arakaki Toshiya Oribe Yoshiro Takeda 《Molecular and cellular biochemistry》1986,70(2):121-130
Summary A two-chain polypeptide, which corresponds to amino acid residues 115–143 and 144–184(185) of bovine serum albumin, connected to each other by a disulfide bridge, potentiated the effects of insulin on glucose transport and glucose metabolism in isolated rat adipocytes. Although the peptide alone had little activity, it shifted the concentration-response curves of insulin-stimulated D-[I-14C]glucose oxidation, 2-deoxyglucose transport, and lipid synthesis from D-[U-14C]glucose to lower insulin concentrations. It also increased the maximal responses of these parameters to insulin. However, it did not affect insulin binding to adipocytes. The peptide protected insulin considerably from degradation, but this effect alone cannot account for its effect in increasing the maximal responses to the hormone, and even when degradation of a submaximal concentration of insulin was suppressed by bacitracin, the peptide still had an enhancing effect. These results suggest not only that the peptide influences a step distal to receptor-mediated insulin binding but also that inhibition of insulin degradation alone cannot explain its total effect.The peptide lost its insulin-stimulating activity completely when it was further digested with V8 or lysinespecific endopeptidase, or when it was reduced and then carboxamidomethylated or oxidized with performic acid. Similar active tryptic fragments were obtained from human and rat albumins.Insulin-stimulating peptides should be useful in studies on the mechanisms of insulin action including both the sensitivities and responsiveness of target cells to the hormone.Abbreviations ISP
insulin-stimulating peptide
- HEPES
N-(2-hydroxyethyl)piperazine-N-2-ethanesulfonic acid
- HPLC
high-performance liquid chromatography
- SDS
sodium dodecyl sulfate 相似文献
67.
68.
Number of hits necessary for complement-mediated hemolysis 总被引:1,自引:0,他引:1
J Takeda H Kozono Y Takata K Hong T Kinoshita K Sayama E Tanaka K Inoue 《Microbiology and immunology》1986,30(5):461-468
The number of hits necessary for the C8 and C9 steps of immune hemolysis was reexamined with a previously unemployed experimental design, in which various numbers of EAC1-7, excess of the supplementary component and a constant amount of the component tested were incubated in a constant volume (Inoue et al. 1976. Infect. Immun. 13: 337). Our results were consistent with previous findings; the steps of guinea pig C8 and C9, the human C8 each followed a one-hit mechanism, while that of human C9 showed ka multi-hit response. When lysis of sensitized erythrocytes (EA) by normal human serum was analysed in a similar way, one-hit curves were obtained. This result, taken together with the above results, suggests that immune hemolysis occurs by a single lesion including a single C8 and multiple C9 in the case of human complement and that normal human serum contains sufficient excess of C9. On the other hand, when C9-deficient human serum was used for lysis of EA, multiple-hit curves were obtained. The mechanism of lysis by C5b-8 may differ from that by C5b-9. 相似文献
69.
Isolation of virus causing hemorrhagic fever with renal syndrome (HFRS) through a cell culture system 总被引:4,自引:0,他引:4
T Kitamura C Morita T Komatsu K Sugiyama J Arikawa S Shiga H Takeda Y Akao K Imaizumi A Oya N Hashimoto S Urasawa 《Japanese journal of medical science & biology》1983,36(1):17-25
Twenty-three rat lung specimens collected in outbreaks of hemorrhagic fever with renal syndrome (HFRS) in three medical institutions were inoculated onto the VERO-E6 cell monolayers. After several blind passages, an agent growing serially in the cell cultures and reacting specifically with known HFRS-positive sera was isolated from two of these specimens. The two isolates were antigenically identical each other. The agent, named strain SR-11, was identified as the causative virus of HFRS by its antigenic identity with E6 cell-adapted HFRS virus, Hantaan 76-118 strain, and the specific reactions with sera from various HFRS cases. 相似文献
70.
Takeda Junko; Abe Shunnosuke; Morikawa Hiromichi; Senda Mitsugi 《Plant & cell physiology》1983,24(4):667-676
The electrophysiological properties of the membrane of Nicotianatabacum var. Sarnsun cultured cells were determined using amicroelectrode technique in standard medium containing 1 mMKC1, 1 mM NaCl and 1 mu CaCl2 at pH 7. Tobacco callus was derivedfrom the pith (Em=104.4%16.2 mV). The membrane potentialsof the callus cells did not show a symmetrical Gaussian distributionbut were scattered over a wide range. The percentage of highmembrane potential cells increased as the subculture was continueduntil about 11 months and then decreased. The response of themembrane potential to electric stimulus, ionic composition,metabolic inhibitors, sugars and amino acids was characteristicof high (Em={small tilde}160 220 mV; H-cells)and low (Em=80{small tilde}90 mV; L-cells) membranepotential cells. The membrane potential of H-cells was largelydepolarized by addition of CN, carbonium cyanide m-chlorophenylhydrazone,decyclohexylcarbodiimide, and triphenyltin chloride and transientlydepolarized by addition of glucose, galactose, mannose or sucrose,and D-alanine, L-alanine or Llysine, but the membrane potentialof L-cells was not. (Received December 3, 1982; Accepted March 16, 1983) 相似文献