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221.
A putative cytosolic alpha-mannosidase gene from a hyperthermophilic marine bacterium Thermotoga maritima was cloned and expressed in Escherichia coli. The purified recombinant enzyme appeared to be a homodimer of a 110-kDa subunit. The enzyme showed metal-dependent ability to hydrolyze p-nitrophenyl-alpha-D-mannopyranoside. In the absence of a metal, the enzyme was inactive. Cobalt and cadmium supported high activity (60 U/mg at 70 degrees C), while the activity with zinc and chromium was poor. Cobalt (0.8 mol) bound to 1 mol monomer with a K(d) of 70 microM. The optimum pH and temperature were 6.0 and 80 degrees C, respectively. The activity was inhibited by swainsonine, but not by 1-deoxymannojirimycin, which is in agreement with the features of cytosolic alpha-mannosidase. 相似文献
222.
Suzuki N Hishinuma T Saga T Sato J Toyota T Goto J Mizugaki M 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2003,783(2):383-389
We developed a determination method for human urinary 12-hydroxyeicosatetraenoic acid (12-HETE) using LC-MS-MS. This method, which includes simple extraction and detection in the SRM mode, allows precise and accurate determination of 12-HETE. There was a significant sex difference in urinary 12-HETE levels. Chiral analysis of 12-HETE using LC-MS-MS with column-switching technique revealed that the major enantiomer was 12(S)-HETE. Furthermore, the urinary level in patients with diabetes mellitus (DM) was analyzed. The present in vivo findings indicate that there could be difference in production of 12(S)-HETE between genders and 12(S)-HETE may play a role in the pathogenesis of DM. 相似文献
223.
Yamada K Suzuki T Kohara A Hayashi M Hakura A Mizutani T Saeki K 《Mutation research》2002,521(1-2):187-200
Benzo[a]pyrene (BaP), an environmental carcinogen, shows genotoxicity after metabolic transformation into the bay-region diol epoxide, BaP-7,8-diol 9,10-epoxide. 10-Azabenzo[a]pyrene (10-azaBaP), in which a ring nitrogen is located in the bay-region, is also a carcinogen and shows mutagenicity in the Ames test in the presence of the rat liver microsomal enzymes. In order to evaluate the effect of aza-substitution on in vivo genotoxicity, BaP and 10-azaBaP were assayed for their in vivo mutagenicity using the lacZ-transgenic mouse (MutaMouse). BaP was potently mutagenic in all of the organs examined (liver, lung, kidney, spleen, forestomach, stomach, colon, and bone marrow), as described in our previous report, whereas, 10-azaBaP was slightly mutagenic only in the liver and colon. The in vitro mutagenicities of BaP and 10-azaBaP were evaluated by the Ames test using liver homogenates prepared from several sources, i.e. CYP1A-inducer-treated rats, CYP1A-inducer-treated and non-treated mice, and humans. BaP showed greater mutagenicities than 10-azaBaP in the presence of a liver homogenate prepared from CYP1A-inducer-treated rodents. However, 10-azaBaP showed mutagenicities similar to or more potent than BaP in the presence of a liver homogenate or S9 from non-treated mice and humans. These results indicate that 10-aza-substitution markedly modifies the nature of mutagenicity of benzo[a]pyrene in both in vivo and in vitro mutagenesis assays. 相似文献
224.
Blood protein polymorphism of gelada baboon (Theropithecus gelada) to the south of the Rift Valley, Arsi Region, were examined for 36 genetic loci using three electrophoresis techniques for
48 blood samples from three localities, and compared with the northern geladas. New variant alleles and genetic markers of
Hb-α, PA-2, and TBPA loci were detected. The distribution patterns of the variant alleles of Hb-α, PA-2, TBPA, Pi, Gc, PGM-II,
and TBPA loci were localized in the geographic regions of south and north gelada populations, respectively. Genetic variability
of southern geladas was estimated as Ppoly=0.083 and
, which was comparable to northern geladas. A remarkably high genetic differentiation between the two geographic populations
was shown byNei's genetic distance=0.071 and GST value=0.420. Our results of genetic analysis suggest that the southern and northern gelada populations have been separated
for several hundred thousand years, and gene flow between the two geographic populations is severely restricted. The southern
gelada baboon may be regarded as a distinct subspecies. 相似文献
225.
Mitsutoshi Kitao Thomas T. Lei Takayoshi Koike Hiroyuki Tobita Yutaka Maruyama 《Physiologia plantarum》2003,118(3):406-413
The influence of long‐term drought stress on photosynthesis of Japanese mountain birch (Betula ermanii Cham.) was examined using chlorophyll fluorescence and gas exchange measurements. Drought stress was imposed in potted plants by reducing irrigation frequency from daily (control) to twice‐weekly and once‐weekly. Thirty‐day‐old leaves, which had developed under fully stressed conditions, were used for the measurements. The decline in net CO2 assimilation rate (A) observed in situ in drought‐stressed plants resulted from a lower intercellular CO2 concentration (Ci) due to stomatal closure but the carboxylation efficiency was not affected as there was no difference in the initial slope of the A/Ci response after watering. Although there were no treatment differences in A at Ci below 270 μmol mol?1 (with ambient air at 360 μmol mol?1 CO2), higher electron transport rate (ETR), photochemical quenching (qP) and the efficiency of energy conversion of open PSII (Fv′/Fm′), and similar or even lower non‐photochemical quenching (NPQ) were observed at a given Ci in drought‐stressed plants (of both twice‐ and once‐weekly irrigation), suggesting a higher fraction of open PSII resulting from energy dissipation achieved through higher electron flow rather than through thermal dissipation in PSII antennae. The once‐weekly watered plants showed a lower ratio of gross carbon assimilation rate to ETR (A*/ETR), suggesting an enhanced alternative pathway of electron flow probably involving the Mehler‐peroxidase (MP) reaction as indicated by a higher ΦPSII at a given ΦCO2 under non‐photorespiratory conditions. On the other hand, plants of twice‐weekly watering exhibited almost the same A*/ETR and ΦPSII–ΦCO2 relationship as control plants, indicating no enhanced alternative pathways under mild drought stress. 相似文献
226.
Shigeki Kishi & Takayoshi Nishida 《Ethology : formerly Zeitschrift fur Tierpsychologie》2006,112(12):1239-1245
If parents can invest resources optimally per offspring, they should adjust the amount of investment in an offspring according to environmental heterogeneity. Many studies have demonstrated changes in egg size or the amount of resource supplied in response to environmental heterogeneity. However, it remains unclear whether parents simply know the resource type a priori or can assess resource quality and adjust the quantity of investment accordingly. We examined the parental capability to adjust the amount of investment per offspring by providing Onthophagus atripennis dung beetle parents with one of three dung types of different quality: monkey dung (high quality), cow dung (low quality), or a mixture of monkey and cow dung (medium quality). The beetle parents cooperatively produce dung brood masses each with one egg under the ground. The size of a brood mass, on which a larva can only feed until adult, represents a large part of the amount of investment. Parents produced a greater number of smaller brood masses given high‐quality resource, while they compensated for low quality of the resource by providing a larger amount of the resource, at the cost of offspring number. However, despite this compensation in the amount of food, offspring raised on low‐quality food was still smaller than offspring raised on high‐quality food. Thus, O. atripennis parents assessed resource quality partly and adjusted the amount of resource provided for their offspring. 相似文献
227.
Bahulekar Raman Tokiwa Takayoshi Kano Junko Matsumura Toshiharu Kojima Isao Kodama Makoto 《Biotechnology Techniques》1998,12(10):721-724
Homo polymers of acrylamide having glucose (PAAm-glucose) and galactose (PAAm-galactose) as pendent groups were synthesized. Tissue culture polystyrene (TCPS) plates coated with these polymers showed increased surface wettability. Coating of PAAm-glucose and PAArn-galactose on to TCPS plates was also confirmed by X-ray photoelectron spectroscopic (XPS) characterization. Rat hepatocytes in primary culture attached to the surfaces of PAArn-galactose homopolymer, but not to those of PAAm-glucose homopolymer. © Rapid Science Ltd. 1998 相似文献
228.
Akira Kobayashi Terumasa Nishiyama Takayoshi Ikegaya Masanori Kaneko Noboru Yamazaki 《Molecular and cellular biochemistry》1993,121(1):59-65
In general, it is recognized that prolonged exposure to catecholamine leads to a reduction in the -adrenoceptor density (downregulation). However, it has been previously reported that the myocardial -adrenoceptor densities and norepinephrine levels significantly increase in the hearts of BIO 14.6 cardiomyopathic hamsters in the early stage. The mechanism of the increased -adrenoceptor density is not clearly elucidated, and it can not be excluded that this phenomenon may be a secondary effect. The purpose of this study was to assess the effect of verapamil on the density of -adrenoceptors in the heart of BIO 14.6 cardiomyopathic hamsters. The total number of -adrenoceptors in untreated BIO 14.6 hamsters was significantly higher at 90 days of age (30.4±2.2 v.s. 25.9±1.4 fmol/mg protein, p<0.05). BIO 14.6 hamsters received daily intraperitoneal injections of 5 mg/kg verapamil for 70 days, from an age of 20 days. Verapamil protected against progressive myocardial damage (total damage; 8.2±0.7 v.s. 0.4±0.2%/area, p<0.05) and the myocardial -adrenoceptor density returned to that of the normal control group (26.9±3.0 fmol/mg protein). Conversely, verapamil did not have an effect on the number of myocardial -adrenoceptors in normal golden hamsters. This study showed that verapamil protected against progressive myocardial damage and myocardial -adrenoceptor density returned to those of normal hamsters. These results suggest that an increased number of -adrenoceptors in the early stage of BIO 14.6 cardiomyopathic hamsters may be involved in the secondary pathogenesis of cardiomyopathy. 相似文献
229.
Takayoshi Nishida 《Population Ecology》1994,36(2):209-218
Spatio-temporal variations of lifetime reproductive succes (LRS) of both male and female individuals of a coreid bugColpula lativentris were measured and analyzed using the multiple regression method of Arnold and Wade (1984a, b). The standardized variance of LRS was larger in males than that in females as males often to secure mates for a long period whereas females could easily find mates and oviposit simply dependent on ovarial maturation. LRS was partitioned into 4 consecutive fitness components: (1) reproductive lifespan, (2) copulating efficiency, (3) guarding efficiency (for males) or oviposition efficiency (for females), and (4) number of eggs per clutch. In males copulating efficiency was the largest determining factor of LRS, whereas in females reproductive lifespan was the most important factor. Such tendencies were stable on both a yearly and local basis. Patterns of relative contribution of natural selection (reproductive lifespan and number of eggs per clutch) and sexual selection (copulating efficiency and guarding or oviposition efficiency) to LRS were clearly different between males and females. This sexual difference is, at least to some extent, thought to be brought about by sexual selection among males for mating opportunity, though no physical fight was observed among males. Directional selection on body length was found only in relation to the clutch size of females because large females tended to lay larger clutches. No significant directional selection was found in other fitness components. 相似文献
230.
Bacteria, yeasts, and molds which grew in a medium containing a synthetic lignin — a dehydrogenation polymer (DHP) of coniferyl alcohol — as a sole carbon source, were isolated from soil. One fungus, Fusarium solani M-13-1, was found to degrade the DHP most vigorously among the isolated organisms. It was shake-cultured in a medium containing dehydrodiconiferyl alcohol (DHCA) (I), an important lignin model compound, and the following six metabolic products were isolated and identified: 1) Phenylcoumaran--aldehydic (II) and -carboxylic compounds, 2) phenylcoumaran--aldehydic compound (IV), formed by release of a 2-carbon fragment from the phenylcoumaran--carboxylic compound, 3) 5-acetylvanillyl alcohol (V), formed by cleavage of the coumaran ring and reduction of the -aldehyde group, 4) 5-carboxyvanillyl alcohol (VI), formed by subsequent oxidation of the acetyl group, and 5) the -ether of DHCA (VII), considered to be a by-product. A degradation pathway for DHCA was proposed on the basis of these metabolic products.Non-Standard Abbreviations DHP
dehydrogenation polymer
- DHCA
dehydrodiconiferyl alcohol
- DDQ
dichlorodicyano-p-benzoquinone
- DDHQ
dichlorodicyano-p-hydroquinone
- Ar
aromatic
- TLC
thin layer chromatography
- GC-MS
gas chromatography-mass spectrometry 相似文献