全文获取类型
收费全文 | 1308篇 |
免费 | 24篇 |
国内免费 | 2篇 |
专业分类
1334篇 |
出版年
2015年 | 11篇 |
2014年 | 15篇 |
2013年 | 121篇 |
2012年 | 13篇 |
2011年 | 20篇 |
2010年 | 54篇 |
2009年 | 111篇 |
2008年 | 35篇 |
2007年 | 14篇 |
2006年 | 12篇 |
2005年 | 15篇 |
2004年 | 30篇 |
2003年 | 34篇 |
2002年 | 45篇 |
2001年 | 28篇 |
2000年 | 33篇 |
1999年 | 41篇 |
1998年 | 47篇 |
1997年 | 51篇 |
1996年 | 13篇 |
1995年 | 20篇 |
1994年 | 11篇 |
1993年 | 24篇 |
1992年 | 11篇 |
1991年 | 9篇 |
1989年 | 17篇 |
1988年 | 24篇 |
1987年 | 15篇 |
1986年 | 17篇 |
1985年 | 22篇 |
1984年 | 12篇 |
1983年 | 18篇 |
1982年 | 12篇 |
1981年 | 24篇 |
1980年 | 11篇 |
1979年 | 19篇 |
1978年 | 23篇 |
1977年 | 27篇 |
1976年 | 19篇 |
1975年 | 19篇 |
1974年 | 15篇 |
1966年 | 10篇 |
1964年 | 12篇 |
1963年 | 7篇 |
1959年 | 7篇 |
1953年 | 11篇 |
1949年 | 14篇 |
1948年 | 6篇 |
1853年 | 8篇 |
1852年 | 7篇 |
排序方式: 共有1334条查询结果,搜索用时 0 毫秒
1.
2.
3.
4.
5.
l-Methionine-dl-sulfoximine (MSX) stimulated nitrate uptake but inhibited14CO2 fixation and O2 evolution inAnabaena doliolum. Nitrate uptake was inhibited by ammonium (NH
4
+
) in the absence of MSX, but not in the presence of MSX. Glutamine or a derivative of it appears to be the actual negative effector of nitrate utilization. In presence of nitrate, MSX-treated cells ofA. doliolum evolve more O2 than do untreated cells. Our results suggest a close relation between photoassimilation of carbon and utilization of nitrogen. 相似文献
6.
Molecular cloning and characterization of human atrial and ventricular myosin alkali light chain cDNA clones 总被引:9,自引:0,他引:9
M Kurabayashi I Komuro H Tsuchimochi F Takaku Y Yazaki 《The Journal of biological chemistry》1988,263(27):13930-13936
We have isolated essentially full-length cDNA clones for atrial (ALC1) and ventricular (VLC1) myosin alkali light chains from a human fetal heart cDNA library. Comparison of overall nucleotide sequences of ALC1 and VLC1 cDNA clones has revealed that, while these two inserts show significant DNA sequence homology (78.4%) with respect to their coding regions, the 5'- and 3'-untranslated regions are highly divergent. Our statistical analysis suggests that human ALC1 and VLC1 diverged approximately 300 million years ago, during the time of separation of birds and mammals. RNA blot analysis shows that ALC1 mRNA is expressed in fetal ventricular and fetal skeletal muscles as well as fetal and adult atrial muscles and VLC1 mRNA is expressed in adult slow skeletal muscle as well as fetal and adult ventricular muscles. Southern blot analysis indicates that each protein is encoded by a single gene. Finally, we show that VLC1 mRNA is induced in pressure-overloaded human atrium. 相似文献
7.
A range of surfactants, including the anionic sodium dodecyl sulfate, the cationic cetyltrimethylammonium bromide and the nonionics octylphenoxy polyethoxyethanol (Triton X100) and polyoxyethylene 20 sorbitan monoleate (Tween 80) was studied for effects on proliferation, contractibility and attachment of cultured human fibroblasts. Only ionic surfactants exhibited a stimulatory effect on fibroblast proliferation, whereas all the surfactants tested increased the contraction of collagen gels containing fibroblasts, with the greatest effect from the non-ionic surfactants. This activity was not correlated with an increase of cell population or cell attachment within the collagenous matrix. The activity of the surfactants was seen only at levels close to their LD50 values and in a narrow range of concentrations. Thus, we consider that they are the result of the so-called hormesis phenomenon.Abbreviations CTAB
cetyltrimethyl-ammonium bromide
- FCS
fetal calf serum
- LD100
dose lethal to 100% of exposed
- MCD
maximal contraction dose
- PDL
population doubling level
- SDS
sodium dodecyl sulfate 相似文献
8.
K Inada S Endo K Takahashi M Suzuki T Narita T Yoshida H Suda T Komuro M Yoshida 《Microbiology and immunology》1991,35(4):303-314
We established a new method of plasma treatment for the removal of interfering factors in the plasma to allow detection of endotoxin by limulus test. The limulus test used was an endotoxin-specific chromogenic test, the Endospecy test. Perchloric acid (PCA) treatment and centrifugation (PCA method) is usually used to remove interfering factors from plasma, with the precipitate being discarded and the supernatant used to detect endotoxin. As the solubilized precipitates of endotoxin-spiked plasma and some patient plasma were found to contain the Endospecy activity, we have devised a new method assaying endotoxin in both the supernatant and precipitate. This study confirmed that the solubilized precipitate of endotoxin-spiked plasma had Endospecy activity and found that the precipitate had other endotoxin activities, such as lethality in galactosamine-sensitized mice and pyrogenicity in rabbits. We also confirmed that interfering factors were completely removed from plasma samples by this new method. The endotoxin level after the new PCA method was found to be about 8 times higher than that determined after PCA treatment and the new PCA method surpasses the conventional PCA method with regard to the positive rate of endotoxin contents in clinical samples. These results indicate that the new PCA method is superior to the PCA method as a plasma pretreatment method for limulus test. 相似文献
9.
E Niki M Takahashi J Tsuchiya E Komuro E Ito K Terao 《Chemico-biological interactions》1988,67(1-2):81-93
The abilities of two kinds of water-soluble diarylamines, disodium 4-chloro-2,2'-iminodibenzoate (CCA) and disodium 4-chloro-3',6'-dimethyl-2,2'-iminodibenzoate (CCM), to protect lipids, membranes and biological tissues from oxidative damages have been studied. The experimental systems studied include the oxidations of methyl linoleate micelles and soybean phosphatidylcholine (Pc) liposomal membranes in aqueous dispersions, oxidative hemolysis of rabbit erythrocytes, and the in vivo oxidative damages of biological tissues all induced by free radicals generated from an azo radical initiator. The two diarylamines functioned as moderate chain-breaking antioxidants and retarded the above oxidations. 相似文献
10.
Partial purification of two distinct enkephalin-degrading aminopeptidases from human cerebrospinal fluid 总被引:1,自引:0,他引:1
In human cerebrospinal fluid, aminopeptidase, dipeptidyl aminopeptidase, dipeptidyl carboxypeptidase, and carboxypeptidase which were capable of hydrolyzing enkephalins were detected. Among these enzymes, two distinct aminopeptidase, designated C-AP1 and C-AP2, were partially purified. These enzymes were not purified thoroughly, but the characteristics of C-AP2 were similar to those of an aminopeptidase purified from monkey brain. But the inhibitory activity of amastatin on C-AP2 was stronger, and that of substance P was negligible. On the other hand, characteristics of C-Ap1 were extremely differ from those of C-AP2 or an aminopeptidase purified from monkey brain. C-AP1 had an optimum pH more in the acidic range (the highest at pH 6.0) and was not inhibited by any of the protease inhibitor tested including bestatin and amastatin. 相似文献