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901.
López-Marín LM Segura E Hermida-Escobedo C Lemassu A Salinas-Carmona MC 《FEMS immunology and medical microbiology》2003,36(1-2):47-54
Mycobacterial O-acyltrehaloses have been described as highly specific and sensitive reagents for tuberculosis immunodiagnosis. An O-acyltrehalose-containing lipid fraction from the rapidly growing Mycobacterium fortuitum was found to include additional antigens, which presented high cross-reactivity with sera from tuberculosis-infected patients. Based on a combination of selective chemical degradations, thin-layer-chromatography analyses and (1)H-nuclear magnetic resonance spectroscopy, the antigenic by-product was identified as 6,6'-dimycoloyl trehalose, the so-called cord factor. The lipid was purified and tested in ELISA for pulmonary tuberculosis serodiagnosis. Sensitivity and specificity of the test were found to be 66.6-74.1% and 95.2-99.0%, respectively, showing a slightly higher efficiency as compared to the ELISA performed using 6,6'-dimycoloyl trehalose from Mycobacterium tuberculosis. No cross-reactivity was found with sera from Nocardia-infected individuals. 相似文献
902.
This work describes the long-term acclimation of the halotolerant microalga Dunaliella viridis to different photon irradiance, ranging from darkness to 1500 μmol m−2 s−1. In order to assess the effects of long-term photoinhibition, changes in oxygen production rate, pigment composition, xanthophyll
cycle and in vivo chlorophyll fluorescence using the saturating pulse method were measured. Growth rate was maximal at intermediate irradiance
(250 and 700 μmol m−2 s−1). The increase in growth irradiance from 700 to 1500 μmol m−2 s−1 did not lead to further significant changes in pigment composition or EPS, indicating saturation in the pigment response
to high light. Changes in Photosystem II optimum quantum yield (Fv/Fm) evidenced photoinhibition at 700 and especially at 1500 μmol m−2 s−1. The relation between photosynthetic electron flow rate and photosyntetic O2 evolution was linear for cultures in darkness shifting to curvilinear as growth irradiance increased, suggesting the interference
of the energy dissipation processes in oxygen evolution. Carbon assimilation efficiencies were studied in relation to changes
in growth rate, internal carbon and nitrogen composition, and organic carbon released to the external medium. All illuminated
cultures showed a high capability to maintain a C:N ratio between 6 and 7. The percentage of organic carbon released to the
external medium increased to its maximum under high irradiance (1500 μmol m−2 s−1). These results suggest that the release of organic carbon could act as a secondary dissipation process when the xanthophyll
cycle is saturated.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
903.
Méndez AT Roig-López JL Santiago P Santiago C García-Arrarás JE 《Marine biotechnology (New York, N.Y.)》2000,2(3):231-240
The Echinodermata is a unique animal group forming an early branch in the deuterostomes phylogenetic tree. In echinoids and
asteroids a single Hox cluster with nine cognates of the vertebrate Hox paralogous groups has been reported, but no data are available from other echinoderm classes. We report here nine Hox-type sequences from the sea cucumber Holothuria glaberrima, a member of the class Holothuroidea. Partial homeodomain sequences were amplified by polymerase chain reaction from genomic
DNA and from a regenerating gastrointestinal tract complementary DNA library. Sequence analyses suggest that the holothuroid
cluster has at least three genes of the anterior, one of the medial, and five of the posterior groups. This is the first evidence
of five posterior sequences in echinoderms.
Received July 19, 1999; accepted October 18, 1999. 相似文献
904.
Association of the low-density lipoprotein receptor gene with obesity in Native American populations 总被引:3,自引:0,他引:3
Five low-density lipoprotein receptor gene (LDLR) restriction fragment length polymorphisms (RFLPs: TaqI, intron 4; HincII, exon 12; AvaII, exon 13; MspI and NcoI, exon 18) were investigated in 131 individuals from five Brazilian Indian tribes. All markers were polymorphic in this ethnic group. In the whole sample of Amerindians, 13 (41%) of the 32 expected haplotypes were identified, but only three were shared by all tribes. The Xavante, Suruí, Zoró, and Gavi?o tribes, who had been studied for anthropometry, were grouped according to their genotypes, and the corresponding mean values were examined. Significant associations were observed between HincII *H-, AvaII *A+, MspI *M-, and NcoI *N+ and the body mass index (BMI), triceps and subscapular skinfolds, and the arm fat index (AFI). Haplotypes were derived for these four RFLPs, and (*H-/*A+/*M-/*N+) haplotype carriers were compared with noncarriers of this haplotype with equally significant results for the three parameters (BMI, P=0.021; skinfold thickness, P<0.001; AFI, P=0.005). These results suggest that the LDLR gene has some influence over adipose tissue deposition. 相似文献
905.
Benintende GB López-Meza JE Cozzi JG Piccinetti CF Ibarra JE 《Current microbiology》2000,41(6):396-401
Several isolates of Bacillus thuringiensis native to Argentina obtained in a nationwide screening program showed atypical crystal morphology. One of these strains,
INTA 51-3, was further characterized in order to determine other features like protein composition of its parasporal crystal,
plasmid pattern, identification of cry genes and toxicological properties. B. thuringiensis INTA 51-3 (serovar tohokuensis) had an amorphous inclusion containing a major protein component of ca. 130 kDa. After trypsin digestion of solubilized crystals, SDS-PAGE resolved a unique protease-resistant peptide of ca. 90 kDa. The plasmid pattern from INTA 51-3 resembled that of the standard strain HD-1. However, Southern analysis showed
no hybridization to fragments of cry1Aa, cry2Aa, cry3A, and cry11A genes. Degenerate primers were used for identification of the cry1 genes by PCR. Nevertheless, the presence of cry1 type gene(s) in B. thuringiensis INTA 51-3 was confirmed. Highly concentrated crystal suspensions showed to be weakly toxic only to lepidopteran species.
Received: 23 May 2000 / Accepted: 26 June 2000 相似文献
906.
The association of tubulin carboxypeptidase with microtubules has been demonstrated in crude brain extracts and in living non-nervous cells. Here, we studied this phenomenon in cultured brain cells. To determine the association of the enzyme with neural microtubules we isolated the cytoskeletons (detergent-extraction under microtubule-stabilizing conditions) and measured the content of Tyr, Glu, and 2 tubulin as a function of the in vitro incubation time of the cytoskeletons. The carboxypeptidase was found associated with microtubules in 2 days-cultured cells but not in 7 days-cultured cells. Quantitative analysis of digitized images after immunofluorescent staining revealed that detyrosination during the incubation of the cytoskeletons occurred preferentially in the distal regions of the neural processes. Prolonged taxol-treatment of the cells promoted higher detyrosination but Tyr tubulin was not depleted suggesting the existence of a subset of microtubules that has not associated carboxypeptidase and therefore cannot be detyrosinated even after prolonged taxol-treatment. This hypothesis was supported, although not conclusively, by additional experiments. 相似文献
907.
Ricardo Barra Juan Carlos Colombo Gabriela Eguren Nadia Gamboa Wilson F. Jardim 《Neurochemical research》2000,25(1):1-1
Dedication
Special Issue Dedicated to Dr. Héctor S. Barra 相似文献908.
909.
Astyanax scabripinnis specimens from four distinct populations in Brazil were studied with respect to their karyotype macrostructure, nucleolar
organizer regions, and 18S and 5S rRNA genes. The four populations showed a 2n = 50 chromosomes (3 M + 11 SM + 5 ST + 6 A pairs) and 1–2 B chromosomes. No chromosomal differentiations were observed between
sexes. Although a karyotypic diversity has been characterized in this fish group, the populations now analyzed presented the
same macrokaryotypic pattern. Chromosome mapping of 5S rDNA showed a total of eight sites located in four distinct chromosomal
pairs, with no apparent differences among populations. A comparative study on 18S rDNA locations and Ag-NORs showed some secondary
NOR sites that are not usually expressed in karyotypes and a probable differential NOR activity among populations. Correlations
between these data, environmental conditions and B chromosomes are discussed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
910.
Specimens of Astyanax scabripinnisfrom three different altitudes (1920, 1800 and 700?m) along the Ribeirão Grande stream in the Campos do Jordão region (São Paulo State, Brazil) were investigated. The same diploid number, 2n?=?50, was detected in the three populations, with the following karyotypic constitution: 6M, 22SM, 10ST and 12A. The populations located at 1920 and 1800?m altitude presented a high incidence of B chromosomes varying in number (0–2), shape (meta- and submetacentrics), size (large and small) and sex-related frequency (they were more frequent among females). The two morphologically variant B chromosomes probably evolved from a metacentric macrochromosome, which is the most commonly observed B chromosome in several A. scabripinnispopulations. 相似文献