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991.
Kouwen TR Andréll J Schrijver R Dubois JY Maher MJ Iwata S Carpenter EP van Dijl JM 《Journal of molecular biology》2008,379(3):520-534
Thioredoxin functions in nearly all organisms as the major thiol-disulfide oxidoreductase within the cytosol. Its prime purpose is to maintain cysteine-containing proteins in the reduced state by converting intramolecular disulfide bonds into dithiols in a disulfide exchange reaction. Thioredoxin has been reported to contribute to a wide variety of physiological functions by interacting with specific sets of substrates in different cell types. To investigate the function of the essential thioredoxin A (TrxA) in the low-GC Gram-positive bacterium Bacillus subtilis, we purified wild-type TrxA and three mutant TrxA proteins that lack either one or both of the two cysteine residues in the CxxC active site. The pure proteins were used for substrate-binding studies known as “mixed disulfide fishing” in which covalent disulfide-bonded reaction intermediates can be visualized. An unprecedented finding is that both active-site cysteine residues can form mixed disulfides with substrate proteins when the other active-site cysteine is absent, but only the N-terminal active-site cysteine forms stable interactions. A second novelty is that both single-cysteine mutant TrxA proteins form stable homodimers due to thiol oxidation of the remaining active-site cysteine residue. To investigate whether these dimers resemble mixed enzyme-substrate disulfides, the structure of the most abundant dimer, C32S, was characterized by X-ray crystallography. This yielded a high-resolution (1.5Å) X-ray crystallographic structure of a thioredoxin homodimer from a low-GC Gram-positive bacterium. The C32S TrxA dimer can be regarded as a mixed disulfide reaction intermediate of thioredoxin, which reveals the diversity of thioredoxin/substrate-binding modes. 相似文献
992.
Breeding antarctic krill in captivity 总被引:5,自引:0,他引:5
Yasuo Hirano Tsuyoshi Matsuda So Kawaguchi 《Marine and Freshwater Behaviour and Physiology》2003,36(4):259-269
Antarctic krill were maintained in large aquaria at Port of Nagoya Aquarium, Japan, under controlled photoperiod and were fed on phytoplankton and enriched animal feed. Maturation and spawning were induced after the light : dark (L : D) cycle was increased from 8 : 16 or 12 : 12 to 24 : 0, or when the L : D cycle was held constant at 14 : 10. This study is one of the first studies that demonstrate initiation of maturation and spawning events of krill under controlled photoperiod. Out of three experimental batches of krill, a total of 28 spawning events were observed. The mean number of eggs per event was 1424 with a range between 139 and 3458. The mean hatching success per batch was 19.1%. The relation between photoperiod and maturity/spawning is discussed. Furthermore, hatching is compared to previous studies and the reason for the low success is discussed. 相似文献
993.
So Jae-Seong Lim Hyoung Taek Oh Eun-Taex Heo Tae-Ryeon Koh Sung-Cheol Leung Kam Tin Lee Hung Trevors Jack T. 《World journal of microbiology & biotechnology》2002,18(1):17-21
The plant pathogen, Xanthomonas campestris NRRL B-1459 was chromosomally tagged with gfp, and the transformant, which was subjected to Southern hybridization showed the presence of gfp in the chromosome. The virulence-related gene of the transformant was not affected by the insertion of gfp. After inoculation into cabbage plants, the infection process was visually studied in planta. Using a fluorescence microscope, the migration and distribution of gfp-labelled bacteria was visualized in real time. As the gfp-labelled cells were easily visualized from the beginning of infection, we observed a time delay of 2 days between distribution of the Xanthomonas cells in cabbage plant and the appearance of visible necrosis. 相似文献
994.
Hitoshi Horie Hiromu Yoshida Kumiko Matsuura Miwako Miyazawa Yoshihiro Ota Takashi Nakayama Yutaka Doi So Hashizume 《Applied and environmental microbiology》2002,68(1):138-142
Sixteen type 1 poliovirus strains were isolated from a sewage disposal plant located downstream of the Oyabe River in Japan between October 1993 and September 1995. The isolates were intratypically differentiated as vaccine-derived strains. Neutralizing antigenicity analysis with monoclonal antibodies and estimation of neurovirulence by mutant analysis by PCR and restriction enzyme cleavage (MAPREC) were performed for 13 type 1 strains of these isolates. The isolates were classified into three groups. Group I (five strains) had a variant type of antigenicity and neurovirulent phenotype. Group II (four strains) had the vaccine type of antigenicity and neurovirulent phenotype. Group III (four strains) had the vaccine type of antigenicity and an attenuated phenotype. Furthermore, it was demonstrated that the virulent isolates were neutralized by human sera obtained after oral poliomyelitis vaccine (OPV) administration, and the sera of rats immunized with inactivated poliovirus vaccine. Although vaccination was effective against virulent polioviruses, virulent viruses will continue to exist in the environment as long as OPV is in use. 相似文献
995.
Qiuju Yuan David E. Scott Kwow-Fai So Zhixiu Lin Wutian Wu 《Neurochemical research》2009,34(11):1907-1913
Previous investigations from this laboratory have demonstrated that hypophysectomy induces up-regulation of neuronal nitric
oxide synthase (nNOS) in magnocellular neurons of the mammalian hypothalamo-neurohypophyseal system (HNS). Accompanied by
this upregulation of nNOS, both neuronal regeneration and degeneration are also observed in this system following hypophysectomy.
The specific aim of this study was to determine the potential role of nNOS upregulation in neuronal survival and regeneration
after hypophysectomy in the adult Sprague–Dawley (SD) rat by using a competitive nitric oxide synthase blocker, N(G)-nitrol-l-arginine methyl ester (l-NAME). We found that l-NAME treatment effectively blocked the regeneration of magnocellular neurons of the rodent hypothalamus as observed in the
lumen of the third cerebral ventricle following hypophysectomy. However, l-NAME had no effect on the survival of magnocellular neurons in the supraoptic (SON) and paraventricular (PVN) nuclei after
hypophysectomy. These results suggest that the induced increase of nNOS expression enhance the regenerative ability of magnocellular
neurons of the HNS following hypophysectomy. 相似文献
996.
Ga Eun Lee Ho-Sung Lee So Deok Lee Jung-Ho Kim Won-Ki Kim Yong-Chul Kim 《Bioorganic & medicinal chemistry letters》2009,19(3):954-958
Iminium quaternary protoberberine alkaloids (QPA) have been found to be novel P2X7 antagonists. To assess their structure–activity relationships, these compounds were modified at their R1 and R2 groups and assayed for their ability to inhibit the 2′(3′)-O-(4-benzoylbenzoyl)-ATP (BzATP)-induced uptake of fluorescent ethidium by HEK-293 cells stably expressing the human P2X7 receptor, and their ability to inhibit BzATP-induced IL-1β release by differentiated THP-1 cells. Compounds 15a and 15d, with alkyl groups at the R1 position, and especially compound 19h, with the 2-NO2-4,5-dimethoxy-benzyl group at the R2 position, had potent inhibitory efficacy as P2X7 antagonists. 相似文献
997.
Tae Sik Sung Min Ji Kim Soojin Hong Jae-Pyo Jeon Byung Joo Kim Ju-Hong Jeon Seon Jeong Kim Insuk So 《Molecules and cells》2009,27(2):167-173
The classical type of transient receptor potential (TRPC) channel is a molecular candidate for Ca2+-permeable cation channels in mammalian cells. Because TRPC4 and TRPC5 belong to the same subfamily of TRPC, they have been
assumed to have the same physiological properties. However, we found that TRPC4 had its own functional characteristics different
from those of TRPC5. TRPC4 channels had no constitutive activity and were activated by muscarinic stimulation only when a
muscarinic receptor was co-expressed with TRPC4 in human embryonic kidney (HEK) cells. Endogenous muscarinic receptor appeared
not to interact with TRPC4. TPRC4 activation by GTPγS was not desensitized. TPRC4 activation by GTPγS was not inhibited by
either Rho kinase inhibitor or MLCK inhibitor. TRPC4 was sensitive to external pH with pK
a of 7.3. Finally, TPRC4 activation by GTPγS was inhibited by the calmodulin inhibitor W-7. We conclude that TRPC4 and TRPC5
have different properties and their own physiological roles.
These authors contributed equally to this work. 相似文献
998.
Carbachol regulates pacemaker activities in cultured interstitial cells of Cajal from the mouse small intestine 总被引:1,自引:0,他引:1
Keum Young So Sang Hun Kim Hong Moon Sohn Soo Jin Choi Shankar Prasad Parajuli Seok Choi Cheol Ho Yeum Pyung Jin Yoon Jae Yeoul Jun 《Molecules and cells》2009,27(5):525-531
We studied the effect of carbachol on pacemaker currents in cultured interstitial cells of Cajal (ICC) from the mouse small
intestine by muscarinic stimulation using a whole cell patch clamp technique and Ca2+-imaging. ICC generated periodic pacemaker potentials in the current-clamp mode and generated spontaneous inward pacemaker
currents at a holding potential of–70 mV. Exposure to carbachol depolarized the membrane and produced tonic inward pacemaker
currents with a decrease in the frequency and amplitude of the pacemaker currents. The effects of carbachol were blocked by
1-dimethyl-4-diphenylacetoxypiperidinium, a muscarinic M3 receptor antagonist, but not by methotramine, a muscarinic M2 receptor antagonist. Intracellular GDP-β-S suppressed the carbachol-induced effects. Carbachol-induced effects were blocked
by external Na+-free solution and by flufenamic acid, a non-selective cation channel blocker, and in the presence of thapsigargin, a Ca2+-ATPase inhibitor in the endoplasmic reticulum. However, carbachol still produced tonic inward pacemaker currents with the
removal of external Ca2+. In recording of intracellular Ca2+ concentrations using fluo 3-AM dye, carbachol increased intracellular Ca2+ concentrations with increasing of Ca2+ oscillations. These results suggest that carbachol modulates the pacemaker activity of ICC through the activation of non-selective
cation channels via muscarinic M3 receptors by a G-protein dependent intracellular Ca2+ release mechanism. 相似文献
999.
1000.
Molecular cloning and characterization of a serine protease-like protein from silkworm (Bombyx mori)
TheBombyx mori (B. mori) serine protease-like protein (BmSp) coding region (946 bp, GenBank accession number of mRNA, DQ118520; protein, AAZ40503) was generated from two separate and overlapping cDNA fragments using sequence homology withTrichoplusia ni azurocidin in aBombyx EST database (Silkbase; http://www.ab.a.u-tokyo.ac.jp/silkbase/). The deduced amino acid sequence of BmSp, which encodes 303 amino acids, shows 44% amino acid identity toA. gambiae serine protease (CAA89967), 43% amino acid identity toSarcophagi peregrina 26-kDa protease, an antibacterial protein and 31% identity toB. mori serine protease-2 (BmSP-2), a potential antiviral protein. Typical features of the BmSp included the serine protease active site triad His / Asp / Ser, three pairs of cysteine residues for disulfide bridges, and three residues, Asp / Gly / Gly, that help to confer trypsin-like specificity to the enzymes. Based on the result of sequence comparison and characterization, our results suggest that the BmSp probably the new subfamily of trypsin-like serine protease. Using RT-PCR and enzyme digestion, the full encoding sequence for BmSp was cloned into theE. coli expression vector pGEX-5X-1. The fusion protein GST-BmSp was effectively expressed inE. coli BL21(DE3) pLysS as inclusion bodies, and a denaturation and refolding procedure were performed to obtain soluble GST-BmSp. The purified protein was tested for antibacterial activity against Gram-positive and Gram-negative bacteria, but it did not show antibacterial activity in the agar well diffusion assay and liquid growth inhibition assay. 相似文献