全文获取类型
收费全文 | 4286篇 |
免费 | 349篇 |
国内免费 | 2篇 |
出版年
2021年 | 33篇 |
2020年 | 23篇 |
2019年 | 27篇 |
2018年 | 35篇 |
2017年 | 27篇 |
2016年 | 61篇 |
2015年 | 91篇 |
2014年 | 115篇 |
2013年 | 282篇 |
2012年 | 183篇 |
2011年 | 187篇 |
2010年 | 135篇 |
2009年 | 112篇 |
2008年 | 209篇 |
2007年 | 206篇 |
2006年 | 215篇 |
2005年 | 199篇 |
2004年 | 225篇 |
2003年 | 189篇 |
2002年 | 179篇 |
2001年 | 125篇 |
2000年 | 131篇 |
1999年 | 110篇 |
1998年 | 53篇 |
1997年 | 56篇 |
1996年 | 44篇 |
1995年 | 63篇 |
1994年 | 56篇 |
1993年 | 61篇 |
1992年 | 99篇 |
1991年 | 91篇 |
1990年 | 71篇 |
1989年 | 76篇 |
1988年 | 77篇 |
1987年 | 52篇 |
1986年 | 54篇 |
1985年 | 58篇 |
1984年 | 45篇 |
1983年 | 45篇 |
1982年 | 46篇 |
1981年 | 30篇 |
1980年 | 41篇 |
1979年 | 48篇 |
1978年 | 31篇 |
1977年 | 50篇 |
1976年 | 34篇 |
1975年 | 26篇 |
1974年 | 29篇 |
1973年 | 30篇 |
1969年 | 26篇 |
排序方式: 共有4637条查询结果,搜索用时 15 毫秒
111.
Naoko Sakihama Izumi Nishimura Shigehiro Obata Masateru Shin 《Photosynthesis research》1995,46(1-2):323-328
When 35%-acetone extract of spinach chloroplasts was separated by SDS-PAGE, ferredoxin-NADP reductase (FNR) appeared as a single band at a molecular mass of 35 kDa. After the polypeptides on the SDS-PAGE plate were electroblotted onto PVDF membrane, the FNR band was cut out and analyzed for N-terminal structure in a gas-phase protein sequencer. Two different FNR peptides were identified: one with glutamine at its N-terminus (Gln-FNR) and the other with -pyroglutamic acid (tFNR) fraction was extracted from chloroplasts with their loosely bound FNR (lFNR) fraction removed in advance. The tFNR fraction contained Gln-FNR only. The Gln-FNR could be highly purified by affinity chromatography using a ferredoxin column. The purified Gln-FNR was digested with arginyl endopeptidase for peptide mapping and partial sequence analysis. Primary structure of Gln-FNR differed from that of lFNR
loosely bound FNR
-
tFNR
tightly bound FNR
- -pyroglutamic acid at N-terminus 相似文献
112.
H. Sawada S. Iwasa O. Nishimura K. Kitano 《Applied microbiology and biotechnology》1995,43(3):445-451
For industrial production of human monoclonal antibodies (hmAb) against hepatitis B virus surface antigen (HBsAg), we scaled-up
a short-term perfusion culture in serum-free medium, which was chosen as the most suitable culture method, to a 50-l fermentor
equipped with a rotating shear filter. Using hydrophobic chromatography as the initial step of hmAb purification, the mAb
HBW4, HBW6 and W471 were isolated in good quality from the respective culture broths in yields of approximately 75%. Each
of the three purified hmAb alone, and a cocktail of the three, protected chimpanzees against HB virus, when injected intravenously
3 h after viral challenge, as long as the serum antibody levels were significant. A pharmacokinetic study using cynomolgus
monkeys demonstrated that the hmAb have a long plasma half-life and bioavailability of approximately 76% upon intramuscular
injection in primates. Thus, anti-HBsAg hmAb produced by an industrial process are expected to be successfully used in clinical
fields.
Received: 20 June 1994/Received revision: 16 September 1994/Accepted: 10 October 1994 相似文献
113.
Kimio Fukami Shinya Nishimura Masamichi Ogusa Miki Asada Toshitaka Nishijima 《Hydrobiologia》1997,358(1-3):245-249
A continuous culture system for a benthic food diatom Nitzschia sp. wasestablished by using properties of high nutrient and clean of deep seawater(DSW). DSW collected from 320 m depth in Muroto City, Japan, was introducedinto a glass-pipe bioreactor (14 cm length, 3 cm diam.) containing glassbeads of 0.5 cm diam. as substrata for the alga, and it was incubated at18°C · 80Em–2sec–1 · L:D=14:10. The chlorophyll a yield of benthicdiatoms in a reactor as a unit of surface area of the substratum was only0.001–0.003 g cm–2 when the flow rate of DSW was 0(batch culture conditions). However, when DSW was supplied continuously to areactor, the yield increased to 1.4 g-chl.a cm–2 alongwith the increase in flow rate of DSW. Moreover, amounts of chl.a washed outof the system were negligible, 0.0014 to 0.0045%, even though theflow rate of DSW was as much as 25 times h–1, suggesting thatsloughing of benthic diatoms from the substratum was minimized. Although theyield of diatoms fluctuated significantly at the time that the DSW wascollected, the variation could be minimized by increasing the flow rate ofDSW. These results indicate that the continuous culturing system with DSWsupports the stable and effective mass culture of benthic food diatom. 相似文献
114.
Does endothelin-1 participate in the exercise-induced changes of blood flow distribution of muscles in humans? 总被引:1,自引:0,他引:1
Maeda Seiji; Miyauchi Takashi; Sakane Michiko; Saito Makoto; Maki Shinichi; Goto Katsutoshi; Matsuda Mitsuo 《Journal of applied physiology》1997,82(4):1107-1111
Maeda, Seiji, Takashi Miyauchi, Michiko Sakane, MakotoSaito, Shinichi Maki, Katsutoshi Goto, and Mitsuo Matsuda. Does endothelin-1 participate in the exercise-induced changes of blood flowdistribution of muscles in humans? J. Appl.Physiol. 82(4): 1107-1111, 1997.Endothelin-1(ET-1) is an endothelium-derived potent vasoconstrictor peptide thatpotentiates contractions to norepinephrine in human vessels. Wepreviously reported that the circulating plasma concentration of ET-1is significantly increased after exercise (S. Maeda, T. Miyauchi, K. Goto, and M. Matsuda. J. Appl.Physiol. 77: 1399-1402, 1994). Tostudy the roles of ET-1 during and after exercise, we investigatedwhether endurance exercise affects the production of ET-1 in thecirculation of working muscles and nonworking muscles. Male athletesperformed one-leg cycle ergometer exercise of 30-min duration atintensity of 110% of their individual ventilatory threshold. Plasmaconcentrations of ET-1 in both sides of femoral veins (veins in theworking leg and nonworking leg) and in the femoral artery (artery inthe nonworking leg) were measured before and afterexercise. The plasma ET-1 concentration in the femoralvein in the nonworking leg was significantly increased after exercise,whereas that in femoral vein in the working leg was not changed. Thearteriovenous difference in ET-1 concentration was significantlyincreased after exercise in the circulation of the nonworking leg butnot of the working leg, which suggests that the production of ET-1 wasincreased in the circulation of the nonworking leg by exercise. Thepresent study also demonstrated that the plasma norepinephrineconcentrations were elevated by exercise in the femoral veins of boththe working and nonworking legs, suggesting that the sympathetic nerveactivity was augmented in both legs during exercise. Therefore, thepresent study demonstrates the possibility that the increase inproduction of ET-1 in nonworking muscles may cause vasoconstriction andhence decrease blood flow in nonworking muscles through its directvasoconstrictive action or through an indirect effect of ET-1 toenhance vasoconstrictions to norepinephrine and that these responsesmay be helpful in increasing blood flow in workingmuscles. We propose that endogenous ET-1 contributes tothe exercise-induced redistribution of blood flow in muscles. 相似文献
115.
Hidekazu Nishimura Kanetsu Sugawara Peng Gao Yasushi Muraki Seiji Hongo Fumio Kitame Kiyoto Nakamura 《Microbiology and immunology》1995,39(9):737-740
The HMV-II cells infected with influenza C virus were labeled with inorganic [32P]phosphate to identify phosphorylated proteins. Analysis by radioimmunoprecipitation with antiviral serum or monoclonal antibodies revealed that three major structural proteins of the virus, hemagglutinin-esterase (HE), nucleoprotein (NP), and matrix protein (M1) are all phosphorylated in both infected cells and virions. It was also observed that, in the presence of trypsin (10 μg/ml), the unphosphorylated form of the HE glycoprotein was cleaved efficiently whereas the phosphorylated form was not, raising the possibility that phosphorylation of HE may influence its susceptibility to degradation by proteolytic enzymes. 相似文献
116.
Souichi Morikawa Kazuhiro Ogata Ai Sekikawa Akinori Sarai Shunsuke Ishii Yoshifumi Nishimura Haruki Nakamura 《Journal of biomolecular NMR》1995,6(3):294-305
Summary The solution structure of a specific DNA complex of the minimum DNA-binding domain of the mouse c-Myb protein was determined by distance geometry calculations using a set of 1732 nuclear Overhauser enhancement (NOE) distance restraints. In order to determine the complex structure independent of the initial guess, we have developed two different procedures for the docking calculation using simulated annealing in four-dimensional space (4D-SA). One is a multiple-step procedure, where the protein and the DNA were first constructed independently by 4D-SA using only the individual intramolecular NOE distance restraints. Here, the initial structure of the protein was a random coil and that of the DNA was a typical B-form duplex. Then, as the starting structure for the next docking procedure, the converged protein and DNA structures were placed in random molecular orientations, separated by 50 Å. The two molecules were docked by 4D-SA utilizing all the restraints, including the additional 66 intermolecular distance restraints. The second procedure comprised a single step, in which a random-coil protein and a typical B-form DNA duplex were first placed 70 Å from each other. Then, using all the intramolecular and intermolecular NOE distance restraints, the complex structure was constructed by 4D-SA. Both procedures yielded the converged complex structures with similar quality and structural divergence, but the multiple-step procedure has much better convergence power than the single-step procedure. A model study of the two procedures was performed to confirm the structural quality, depending upon the number of intermolecular distance restraints, using the X-ray structure of the engrailed homeodomain-DNA complex.Abbreviations rmsd
root-mean-square deviation
- NOE
nuclear Overhauser enhancement
- 4D-SA
simulated annealing in four-dimensional space
- Myb-R2R3
repeats 2 and 3 of the DNA-binding domain of the c-Myb protein
- DNA 16
Myb-specific binding DNA duplex with 16 base pairs
- IHDD-C
residues 3 to 59 of the C-chain of the engrailed homeodomain-DNA complex
- DNA11
DNA duplex with base pairs 9 to 19 of the engrailed homeodomain-DNA complex 相似文献
117.
Shinji Hosoi Mitsuo Satoh Hiromasa Miyaji Tatsunari Nishi Tamio Mizukami Mamoru Hasegawa Seiga Itoh Tatsuya tamaoki 《Cytotechnology》1995,19(1):1-10
Pro-UKS1 was designed as a thrombin-resistant derivative of pro-urokinase (pro-UK) by introducing a glycosylation site using site-directed mutagenesis. An expression plasmid for pro-UKS1, pMo1UKS1SEd1-5, was constructed and introduced into Namalwa KJM-1 cells (Hosoiet al., 1988), and cells resistant to G418 and Methotrexate (MTX) were obtained. Amongst them, the highest pro-UKS1 producer (resistant to 500 nM of MTX), clone 41-8, was selected and further characterized. Clone 41-8 was cultured in serum-free ITPSGF medium (Hosoiet al., 1988). Under the conventional conditions, the concentration of pro-UKS1 reached 26 g ml–1. Addition of glucose and tri-iodothyronine (T3) improved productivity, and the maximal productivity of pro-UKS1 was 67 g ml–1 day–1. In this conditioned medium, content of pro-UKS1 was above 80% of total proteins.Abbreviations BSA
bovine serum albumin
- dhfr
dihydrofolate reductase
- HEPES
4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- kb
kilobase pairs
- kDa
kilodaltons
- MTX
Methotrexate
- PBS
phosphate buffered saline
- pro-UK
pro-urokinase
- SDS-PAGE
sodium dodecyl sulfate-polyacrylamide gel electrophoresis
- T3
tri-iodothyronine
- Tween-PBS
phosphate buffered saline containing 0.05% Tween 80 相似文献
118.
Yoshimoto T. Takahashi K. Nishimura H. Ajima A. Tamaura Y. Inada Y. 《Biotechnology letters》1984,6(6):337-340
Summary Lipoprotein lipase modified with polyethylene glycol dissolved in benzene, and catalyzed various reactions of ester synthesis, ester exchange and aminolysis. This modified enzyme had a high stability; 50% of the initial enzymic activity were retained after about 3 months-storage in benzene at room temperature. We can repeatedly re-use the enzyme by recovering from benzene solution; the enzyme precipitates upon addition of n-hexane(or petroleum ether). 相似文献
119.
E Sato M Fujie T Uezato M Fujita K Nishimura 《Biochemical and biophysical research communications》1984,119(3):1168-1173
The composition of intestinal glycosphingolipids during normal and hormone-perturbed development was investigated. The concentrations of glycosphingolipids of mouse small intestine were affected by the injection of thyroxine or cortisone during suckling and weaning periods. GDla was reduced by the hormonal treatment among major gangliosides, GM3, GM1 and GD1a, of mouse small intestine during the suckling period. In contrast, asialo GM1 was precociously produced by the treatment, which scarcely found in control suckling mouse small intestine. The results showed that these hormones were related to developmental alteration of small-intestinal glycolipids. 相似文献
120.