全文获取类型
收费全文 | 2522篇 |
免费 | 127篇 |
出版年
2022年 | 10篇 |
2021年 | 9篇 |
2020年 | 6篇 |
2019年 | 16篇 |
2018年 | 31篇 |
2017年 | 23篇 |
2016年 | 41篇 |
2015年 | 67篇 |
2014年 | 95篇 |
2013年 | 162篇 |
2012年 | 179篇 |
2011年 | 159篇 |
2010年 | 112篇 |
2009年 | 86篇 |
2008年 | 160篇 |
2007年 | 149篇 |
2006年 | 154篇 |
2005年 | 161篇 |
2004年 | 145篇 |
2003年 | 147篇 |
2002年 | 149篇 |
2001年 | 29篇 |
2000年 | 20篇 |
1999年 | 24篇 |
1998年 | 40篇 |
1997年 | 50篇 |
1996年 | 26篇 |
1995年 | 29篇 |
1994年 | 15篇 |
1993年 | 20篇 |
1992年 | 22篇 |
1991年 | 29篇 |
1990年 | 22篇 |
1989年 | 23篇 |
1988年 | 12篇 |
1987年 | 11篇 |
1986年 | 17篇 |
1985年 | 19篇 |
1984年 | 21篇 |
1983年 | 11篇 |
1982年 | 21篇 |
1981年 | 20篇 |
1980年 | 17篇 |
1979年 | 15篇 |
1978年 | 15篇 |
1977年 | 8篇 |
1976年 | 13篇 |
1975年 | 9篇 |
1974年 | 7篇 |
1973年 | 8篇 |
排序方式: 共有2649条查询结果,搜索用时 15 毫秒
41.
Hirofumi Fukushima Shigenobu Umeki Takehito Watanabe Yoshinori Nozawa 《Biochemical and biophysical research communications》1982,105(2):502-508
With the use of detergents and successive column chromatographies, Tetrahymena b-type cytochrome was purified from microsomes to a specific content of 36.0 nmol per mg of protein. The purified form showed a single band on SDS-polyacrylamide gel with molecular weight of 22,000. The spectral properties of the reduced b-type cytochrome, the α-peak of which is situated at 560 nm and asymmetric with a shoulder at 556 nm, was different from that of rat liver microsomal cytochrome b5. However, it was reducible by NADH in the presence of NADH-cytochrome b5 reductase purified from rat liver microsomes.The results indicated that the microsomal b-type cytochrome should be designated as cytochrome b5 of a ciliated protozoan, Tetrahymena pyriformis. 相似文献
42.
Neurotensin and Neuromedin N Are Differently Metabolized in Ventral Tegmental Area and Nucleus Accumbens 总被引:2,自引:2,他引:0
Frédéric Checler Pascale Dauch Yoshinori Masuo Jean-Pierre Vincent 《Journal of neurochemistry》1991,56(4):1320-1328
Whole homogenates and membrane-bound and cytosoluble fractions prepared from rat ventral tegmental area (VTA) and nucleus accumbens were examined for their content of peptidasic activities and for their ability to metabolize neurotensin and its natural related hexapeptide neuromedin N. No qualitative differences were observed between these two brain regions concerning the presence and the subcellular distribution of a series of activities able to hydrolyze various specific fluorimetric enzymatic substrates. However, aminopeptidase B, endopeptidase 24-15, and endopeptidase 24-11 were significantly lower in the VTA than in the nucleus accumbens membrane preparations, while proline endopeptidase was detected in significantly higher amount only in the cytosolic fraction prepared from nucleus accumbens. Both neurotensin and neuromedin N were metabolized more rapidly in the nucleus accumbens than in the VTA. Furthermore, the degradation rate of neuromedin N was considerably faster than that of neurotensin whatever the cerebral area examined. Studies carried out with highly specific peptidase inhibitors revealed that endopeptidase 24-15 mainly contributed to the catabolism of neurotensin in homogenates and membrane-bound preparations of nucleus accumbens and VTA, while aminopeptidase B appeared predominantly responsible for the rapid disappearance of neuromedin N in both cerebral tissues. The possibility that the different metabolic processes of the two peptide congeners could explain their distinct pharmacological profiles observed after their microinjection in the nucleus accumbens and in the VTA is discussed. 相似文献
43.
Effects of Hypoxia on the Activity of the Dopaminergic Neuron System in the Rat Striatum as Studied by In Vivo Brain Microdialysis 总被引:1,自引:0,他引:1
Yoshinori Akiyama Kunio Koshimura Tetsuya Ohue Ken Lee Soichi Miwa Sen Yamagata Haruhiko Kikuchi 《Journal of neurochemistry》1991,57(3):997-1002
The purpose of the present study is to clarify the effects of hypoxia on the activity of the dopaminergic neurons in the brain and its mechanism of action. For this purpose, the effects of hypoxia on the extracellular levels of 3,4-dihy-droxyphenylethylamine (dopamine) were examined in the rat Striatum using in vivo brain microdialysis in the presence or absence of pretreatment with either tetrodotoxin (a blocker of voltage-dependent sodium channels) or nomifensine (a blocker of dopamine reuptake). Exposure to various degrees of hypoxia (15, 10, and 8% O2 in N2) increased dopamine levels in striatal dialysates to 200, 400, and 1,100%, respectively, of the control value. On reoxygenation, dopamine levels in the dialysates rapidly returned to the control level. Reexposure to hypoxia increased the dopamine levels to the same extent as during the first exposure. After addition of tetrodotoxin (40 mUM) to the perfusion fluid or pretreatment with nomifensine (100 mg/kg, i.p.), exposure to hypoxia no longer increased the dopamine levels. These results suggest that although hypoxia induces an increase in the extracellular dopamine levels (hence, an apparent increase in the activity of the dopaminergic neurons), this increase is not the result of an increase in dopamine release itself, but rather the result of inhibition of the dopamine reuptake mechanism. 相似文献
44.
K Yamazaki A Kumazawa K Ito K Kurihara M Nakayama T Wakabayashi 《Laboratory animal science》1992,42(4):378-381
Senescence-accelerated mice (SAM) are one of the animal models used for studying senescence, which consist of several substrains such as SAM-R/1, R/2, P/1, P/2. SAM-R/1/Eis maintained in Eisai Tsukuba Research Laboratories, Ibaraki, Japan, was originally introduced as a substrain of a normal control SAM-R/1 from Kyoto University, Japan. We have noted signs of convulsions in SAM-R/1/Eis mice during routine animal care, particularly while changing cages. We identified the clinical signs and determined the concentrations of glucose and immunoreactive insulin in plasma of SAM-R/1/Eis mice. There were no differences in the male:female ratios of mice showing prodrome only, grand mal, or no-signs. The ages at which prodrome and grand mal were first noted peaked between 20 and 25 weeks. Concentrations of glucose and immunoreactive insulin in plasma did not indicate the mice were in insulin hypoglycemia, which is one cause of convulsions. AKR strain mice, some of which originated with the SAM strain are known to become convulsive by repeated "throwing" stimulations. Conversely, in SAM-R/1/Eis, throwing stimuli are not needed to cause convulsive signs. Thus it is likely that in SAM-R/1/Eis mice the signs are triggered by repeating mild environmental changes, such as changing cages. The results of this study show that SAM-R/1/Eis is neither a normal control strain, nor an original SAM-R/1 strain. But it is possible that SAM-R/1/Eis is another useful animal model for studying spontaneous convulsion. 相似文献
45.
46.
A novel method for the reconstitution of oxygen evolution in cholate-extracted spinach thylakoid membranes was established and a protein essential for the reconstitution was purified from cholate extracts. Purification of the protein was accomplished by chromatography on a DEAE-Sephacel column. This protein (Mr 17 000) was reinserted into vesicular membranes reconstituted from cholate-extracted thylakoids in the presence of 25% glycerol to reactivate oxygen evolution. 相似文献
47.
Yoshinori Asakawa Masao Toyota Reiji Takeda Claude Suire Tsunematsu Takemoto 《Phytochemistry》1981,20(4):725-728
Riccardia species (Metzgeriales) contain various types of sesquiterpenes. R. jackii produces ent-selinane-, ent-aromadendrane-and ent-bicyclogermacrane-type sesquiterpenes together with (R)-cuparene and α-barbatene. Aneura pinguis (= Riccardia pinguis) is chemically quite different from R. multifida and R. jackii. The former produces a large amount of pinguisone. R. multifida contains 6-(3-methyl-2-butenyl)-indole and (+)-β-elemene as the major components. Pallavicinia longispina (Dilaenaceae; Metzgeriales) produces mainly spathulenol. The chiral properties of the sesquiterpenes isolated from R. jackii are quite similar to those of red algae, Laurencia species. 相似文献
48.
A new bibenzyl having a dihydrooxepin ring was isolated from the acetone extract of the liverwort Radula tokiensis, together with the previously known 5 bibenzyls and 3 sesquiterpenes, trans-β-farnesene, cuparene and (Jcuparenol. Two known bibenzyls were isolated from R. japonica. The bibenzyl derivatives are significant chemosystematic markers of the Radulaceae. 相似文献
49.
Eiji Ichishima Yoshinori Tsuruda Taro Ushijima Takehiko Nomi Shoji Suzuki Michio Takeuchi Akiko Yamane 《Current microbiology》1980,4(2):85-89
The enzymological, physical, and immunological properties of soluble and bound forms of intracellular acid carboxypeptidase
isolated from fresh mycelia ofAspergillus saitoi are reported. In the broken mycelia, about 60% of the total activity was found in the 2,000×g precipitate, with most of the remainder in the 100,000×g supernantant. The highly purified enzymes, Ia and Ib, from the 100,000×g supernatant were found to be homogeneous by such criteria as disc gel electrophoresis at pH 9.4 The bound enzyme, II, was
solubilized from the 2,000×g precipitate by self-digestion at pH 6.4 and was highly purified by chromotography. The two forms of intracellular enzymes,
the soluble enzymes (Ia and Ib) from the 100,00×g supernatant and the solubilized enzyme (II) from the 2,000×g precipitate, were closely related to, but not completely identical with, the extracellular acid carboxypeptidase. 相似文献
50.
Teruyoshi Marunaka Toshiaki Shibata Yoshinori Minami Yukihiko Umeno 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1980,183(3):331-338
A high-performance liquid chromatographic method was developed for the simultaneous determination of phenylbutazone and its metabolites, oxyphenbutazone and γ-hydroxyphenylbutazone, in plasma and urine. Samples were acidified with hydrochloric acid and extracted with benzene—cyclohexane (1:1, v/v). The extract was redissolved in methanol and chromatographed on a μBondapak C15 column using a mobile phase of methanol—0.01 M sodium acetate buffer (pH 4.0) in a linear gradient (50 to 100% methanol at 5%/min; flow-rate 2.0 ml/min) in a high-performance liquid chromatograph equipped with an ultra-violet absorbance detector (254 nm). The detection limit for phenylbutazone, oxyphenbutazone and for γ-hydroxyphenylbutazone was 0.05 μg/ml.A precise and sensitive assay for the determination of phenylbutazone and its metabolites was established. 相似文献