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991.
Eutrophication assessment and bioremediation strategy in a marine fish cage culture area in Nansha Bay,China 总被引:3,自引:0,他引:3
On the basis of field data measured during four cruises from January to November 2007, variations in the characteristics of
dissolved inorganic nitrogen and phosphate were analyzed in Nansha marine fish cage culture area, Ningbo City, China. Dissolved
inorganic nitrogen (DIN) was selected as the parameter to balance seaweed absorption and fish DIN production. The contents
of DIN and phosphate varied with different seasons, and eutrophication index (E) value ranged from 2.41 to 15.99, indicating serious eutrophication conditions; the annual average value of N/P of 32.95
indicates a nitrogen surplus in this system. The eutrophication condition in Nansha Bay was mainly caused by the fish cage
culture activities. Based on their biological characteristics, Laminaria and Gracilaria were selected as the bioremediation species in winter and spring and summer and autumn, respectively. The optimal co-cultivation
proportion of fish cage to Laminaria and Gracilaria in this bay was 1 cage, 450 m2 and one cage, 690 m2, respectively. 相似文献
992.
Yun Sook Kim Dae-Sung Lee Seong-Yun Jeong Woe Jae Lee Myung-Suk Lee 《Journal of microbiology (Seoul, Korea)》2009,47(1):9-18
A bacterial strain named AB-4 showing algicidal activity against Chattonella marina was isolated from coastal water of ULjin, Republic of Korea. The isolated strain was identified as Bacillus sp. by culture morphology, biochemical reactions, and homology research based on 16S rDNA. The bacterial culture led to the
lysis of algal cells, suggesting that the isolated strain produced a latent algal-lytic compound. Amongst changes in algicidal
activity by different culture filtrate volumes, the 10% (100 μl/ml) concentration showed the biggest change in algicidal activity;
there, estimated algicidal activity was 95%. The swimming movements of Chattonella marina cells were inhibited because of treatment of the bacterial culture; subsequently, Chattonella marina cells became swollen and rounded. With longer exposure time, algal cells were disrupted and cellular components lost their
integrity and decomposed. The released algicide(s) were heat-tolerant and stable in pH variations, except pH 3, 4, and 5.
Culture filtrate of Bacillus sp. AB-4 was toxic against harmful algae bloom (HAB) species and nontoxic against livefood organisms. Bacillus sp. AB-4 showed comparatively strong activity against Akashiwo sanguinea, Fibriocapsa japonica, Heterosigma akashiwo, and Scrippsiella trochoidea. These results suggest that the algicidal activity of Bacillus sp. AB-4 is potentially useful for controlling outbreaks of Chattonella marina. 相似文献
993.
Coppoolse ER de Vroomen MJ van Gennip F Hersmus BJ van Haaren MJ 《Plant molecular biology》2005,58(5):687-698
Cre/lox recombination in vivo has become an important tool to induce chromosomal rearrangements like deletions. Using a combination of Ds transposition and Cre/lox recombination in two independent experiments on chromosomes 6 and 7 of tomato, two sets of somatic deletions up to a size of 200 kb were obtained. The efficiency of somatic deletion decreased with increasing deletion size. The largest germinally transmitted deletion had a size of only 55 kb. The results show that Cre-mediated deletion in somatic cells is less efficient when the lox sites are separated over larger distances. A further drop of the deletion efficiency after germinal transmission of the larger deletions can be explained by the probable loss of genes that are of vital importance to gametophyte function. Plasmid rescue of an 8.4 kb circularised deleted DNA showed that the Cre-mediated deletion takes place in tomato as expected. Since the circular Cre-deleted DNA could only be PCR amplified in plant cells where the deletion was not complete, the double-stranded DNA circle is assumed to be instable. 相似文献
994.
Glycan microarray analysis of the hemagglutinins from modern and pandemic influenza viruses reveals different receptor specificities 总被引:17,自引:0,他引:17
Stevens J Blixt O Glaser L Taubenberger JK Palese P Paulson JC Wilson IA 《Journal of molecular biology》2006,355(5):1143-1155
Influenza A virus specificity for the host is mediated by the viral surface glycoprotein hemagglutinin (HA), which binds to receptors containing glycans with terminal sialic acids. Avian viruses preferentially bind to alpha2-3-linked sialic acids on receptors of intestinal epithelial cells, whereas human viruses are specific for the alpha2-6 linkage on epithelial cells of the lungs and upper respiratory tract. To define the receptor preferences of a number of human and avian H1 and H3 viruses, including the 1918 H1N1 pandemic strains, their hemagglutinins were analyzed using a recently described glycan array. The array, which contains 200 carbohydrates and glycoproteins, not only revealed clear differentiation of receptor preferences for alpha2-3 and/or alpha2-6 sialic acid linkage, but could also detect fine differences in HA specificity, such as preferences for fucosylation, sulfation and sialylation at positions 2 (Gal) and 3 (GlcNAc, GalNAc) of the terminal trisaccharide. For the two 1918 HA variants, the South Carolina (SC) HA (with Asp190, Asp225) bound exclusively alpha2-6 receptors, while the New York (NY) variant, which differed only by one residue (Gly225), had mixed alpha2-6/alpha2-3 specificity, especially for sulfated oligosaccharides. Only one mutation of the NY variant (Asp190Glu) was sufficient to revert the HA receptor preference to that of classical avian strains. Thus, the species barrier, as defined by the receptor specificity preferences of 1918 human viruses compared to likely avian virus progenitors, can be circumvented by changes at only two positions in the HA receptor binding site. The glycan array thus provides highly detailed profiles of influenza receptor specificity that can be used to map the evolution of new human pathogenic strains, such as the H5N1 avian influenza. 相似文献
995.
Background
Fructans – β-D-fructofuranosyl polymers with a sucrose starter unit – constitute a carbohydrate reservoir synthesised by a considerable number of bacteria and plant species. Biosynthesis of levan (αGlc(1–2)βFru [(2–6)βFru]n), an abundant form of bacterial fructan, is catalysed by levansucrase (sucrose:2,6-β-D-fructan-6-β-D-fructosyl transferase), utilizing sucrose as the sole substrate. Previously, we described the tertiary structure of Bacillus subtilis levansucrase in the ligand-free and sucrose-bound forms, establishing the mechanistic roles of three invariant carboxylate side chains, Asp86, Asp247 and Glu342, which are central to the double displacement reaction mechanism of fructosyl transfer. Still, the structural determinants of the fructosyl transfer reaction thus far have been only partially defined. 相似文献996.
Melissa K. Wilson Alison B. Lane Bibiana F. Law William G. Miller Lynn A. Joens Michael E. Konkel Bryan A. White 《Microbial ecology》2009,58(4):843-855
Campylobacter jejuni is one of the leading bacterial causes of food-borne illness in the USA. Molecular typing methods are often used in food
safety for identifying sources of infection and pathways of transmission. Moreover, the identification of genetically related
isolates (i.e., clades) may facilitate the development of intervention strategies for control and prevention of food-borne
diseases. We analyzed the pan genome (i.e., core and variable genes) of 63 C. jejuni isolates recovered from chickens raised in conventional, organic, and free-range poultry flocks to gain insight into the
genetic diversity of C. jejuni isolates recovered from different environments. We assessed the discriminatory power of three genotyping methods [i.e., pulsed-field
gel electrophoresis (PFGE), multilocus sequence typing (MLST), and repetitive extragenic palindromic polymerase chain reaction
(rep-PCR)]. The rep-PCR fingerprint was generated by determining the presence of repetitive sequences that are interspersed throughout
the genome via repetitive extragenic palindromic PCR, enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR),
and BOX element PCR (BOX-PCR) and combining the data to form a composite fingerprint. The genetic fingerprints were subjected
to computer-assisted pattern analysis. Comparison of the three genotypic methods revealed that repREB-PCR showed greater discriminatory
power than PFGE and MLST. ERIC-PCR and BOX-PCR yielded the highest number of PCR products and greatest reproducibility. Regardless
of the genotyping method, C. jejuni isolates recovered from chickens reared in conventional, organic, and free-range environments all exhibit a high level of
genotypic diversity. 相似文献
997.
d-lactic acid is a versatile and important industrial chemical that can be applied in the synthesis of thermal-resistant poly-lactic acid. Biosynthesis of d-lactic acid can be achieved by a variety of microorganisms, including lactic acid bacteria, yeast, and fungi; however, the final product yield, optical purity, and the utilization of both glucose and xylose are restricted. Consequently, engineered microbial systems are essential to attain high titer, productivity, and complete utilization of sugars. Herein, we critically evaluate the promising wild-type microorganisms, as well as genetically modified microorganisms to produce enantiomerically pure d-lactic acid, particularly from renewable lignocellulosic biomass. In addition, innovative bioreactor operation, metabolic flux analysis, and recent genetic engineering methods for targeted microbial d-lactic acid synthesis will be discussed. 相似文献
998.
Gareth Jones Björn M. Siemers 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2011,197(5):447-457
Ecological constraints often shape the echolocation pulses emitted by bat species. Consequently some (but not all) bats emit
species-specific echolocation pulses. Because echolocation pulses are often intense and emitted at high rates, they are potential
targets for eavesdropping by other bats. Echolocation pulses can also vary within species according to sex, body size, age,
social group and geographic location. Whether these features can be recognised by other bats can only be determined reliably
by playback experiments, which have shown that echolocation pulses do provide sufficient information for the identification
of sex and individual in one species. Playbacks also show that bats can locate conspecifics and heterospecifics at foraging
and roost sites by eavesdropping on echolocation pulses. Guilds of echolocating bat species often partition their use of pulse
frequencies. Ecology, allometric scaling and phylogeny play roles here, but are not sufficient to explain this partitioning.
Evidence is accumulating to support the hypothesis that frequency partitioning evolved to facilitate intraspecific communication.
Acoustic character displacement occurs in at least one instance. Future research can relate genetic population structure to
regional variation in echolocation pulse features and elucidate those acoustic features that most contribute to discrimination
of individuals. 相似文献
999.
1000.