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861.
Responses of phytoplankton diversity to physical disturbance under manual operation in a large reservoir, China 总被引:3,自引:0,他引:3
In aquatic ecosystems, physical disturbances have been suggested to be one of the main factors influencing phytoplankton structure
and diversity. To elucidate whether large-scale artificial operation of a hydroelectric reservoir has potential impacts on
phytoplankton diversity, the impact on phytoplankton biodiversity of physical disturbances under artificial operation from
May 2007 to April 2008 in tributaries of the Three Gorges Reservoir (TGR), China, was analysed. Two disturbance parameters,
i.e. the absolute incremental rates of discharge (R
d,i
) and precipitation (R
p,i
), were created in this study for evaluating physical disturbance intensities during low and high water level periods of the
TGR. Results showed that river discharge seemed to be the main factor controlling the phytoplankton diversity in low water
level periods (≤151 m), and that precipitation was a potential promoter of the physical disturbance. During the 156-m impoundment
process, the species diversity clearly decreased due to the high dilution effect on the phytoplankton communities. At high
water level periods (>151 m), the low levels of disturbance eventually allowed the phytoplankton community to approach competitive
exclusion in late February 2008. Sharply declining diversity values appeared when the Dinophyta blooms occurred in late March
and late April 2008 (Peridinium and Ceratium, respectively). 相似文献
862.
863.
Gao X Appelbee MJ Mekuria GT Chalmers KJ Mather DE 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2012,124(2):333-343
Bread is one of the major constituents of the human diet and wheat (Triticum aestivum L.) is the most important cereal for bread making. The gluten proteins (glutenins and gliadins) are recognised as important
components affecting the processing quality of wheat flour. In this research, we investigated a particular glutenin subunit
allele in an Australian cultivar, H45. Based on protein and DNA assays, the Glu-B1 allele of H45 seems to be Glu-B1al, an allele that includes a functional duplication of a gene encoding an x-type high-molecular-weight glutenin subunit, and
is thought to increase dough strength through overexpression of that subunit. Yet H45 does not have the dough properties that
would be expected if it carries the Glu-B1al allele. After confirming that H45 overexpresses Bx subunits and that it has relatively low un-extractable polymeric protein
(an indicator of weak dough), we cloned and sequenced two Bx genes from H45. The sequences of the two genes differ from each
other, and they each differ by four single-nucleotide polymorphisms (SNPs) from the sequence that has been reported for the
Glu-B1al x-type glutenin genes of the Canadian wheat cultivar Glenlea. One of the SNPs leads to an extra cysteine residue in one of
the subunits. The presence of this additional cysteine may explain the dough properties of H45 through effects on cross-linkage
within or between glutenin subunits. We propose that the Glu-B1 allele of H45 be designated Glu-B1br, and we present evidence that Glu-B1br is co-inherited with low un-extractable polymeric protein. 相似文献
864.
Guan-Zheng Qu Lina Zang Hu Xilin Caiqiu Gao Tangchun Zheng Kai-Long Li 《Plant Molecular Biology Reporter》2012,30(2):512-518
In this study, the additive effects of a late embryogenesis abundant (LEA) gene and a basic leucine zipper (bZIP) gene on salt and osmotic stress in Tamarix plants were analyzed. The constructs containing one or both of the LEA and bZIP genes were transformed into tobacco. Northern blot analysis showed the genes were overexpressed under the control of the
CaMV 35S promoter in both dual and single gene-transgenic tobacco lines. The effects of salt and osmotic stress in transgenic
tobacco plant were investigated. Following exposure to NaCl, mannitol, and PEG6000 stress, dual gene-transgenic lines showed
higher seed generation and growth rates than single gene-transgenic lines and the wild-type. In response to NaCl stress, the
dual gene-transgenic lines showed lower malondialdehyde and higher leaf chlorophyll content than single gene-transgenic lines
and the wild-type. These results suggested that the co-expression of LEA and bZIP resulted in an additive enhancement of stress tolerance in dual gene-transgenic tobacco. 相似文献
865.
Oryzoideae (Poaceae) plants have economic and ecological value. However, the phylogenetic position of some plants is not clear,
such as Hygroryza aristata (Retz.) Nees. and Porteresia coarctata (Roxb.) Tateoka (syn. Oryza coarctata). Comprehensive molecular phylogenetic studies have been carried out on many genera in the Poaceae. The different DNA sequences,
including nuclear and chloroplast sequences, had been extensively employed to determine relationships at both higher and lower
taxonomic levels in the Poaceae. Chloroplast DNA ndhF gene and atpB-rbcL spacer were used to construct phylogenetic trees and estimate the divergence time of Oryzoideae, Bambusoideae, Panicoideae,
Pooideae and so on. Complete sequences of atpB-rbcL and ndhF were generated for 17 species representing six species of the Oryzoideae and related subfamilies. Nicotiana tabacum L. was the outgroup species. The two DNA datasets were analyzed, using Maximum Parsimony and Bayesian analysis methods. The
molecular phylogeny revealed that H. aristata (Retz.) Nees was the sister to Chikusichloa aquatica Koidz. Moreover, P. coarctata (Roxb.) Tateoka was in the genus Oryza. Furthermore, the result of evolution analysis, which based on the ndhF marker, indicated that the time of origin of Oryzoideae might be 31 million years ago. 相似文献
866.
Qianqian Zheng Biao Wang Jian Gao Na Xin Wei Wang Xiaowen Song Yue Shao Chenghai Zhao 《Journal of cellular and molecular medicine》2018,22(1):131-140
CD155, one of the nectin‐like molecule family members, is involved in cell adhesion and motility. CD155 is overexpressed in several human cancers, but its role in proliferation and apoptosis of colorectal cancer remains unclear. We found that CD155 was up‐regulated in colorectal cancer tissues. CD155 knockdown via shRNA lentiviruses inhibited colon cancers cell migration and invasion, with a reduction in the expression of FAK, Src and MMP‐2. CD155 down‐regulation also suppressed colon cancer cell proliferation, accompanied by changing expressions of some molecules related to cell cycle. Finally, CD155 knockdown increased the expression ratio between Bax and Bcl‐2, resulting in a significant increase in colon cancer cell apoptosis. Taken together, these results demonstrate that CD155 is involved in not only migration and invasion but also proliferation and survival abilities of colon cancer cells, suggesting that CD155 is one of key molecules promoting the growth and metastasis of colorectal cancer. 相似文献
867.
Characterization and functional analysis of hsp21.8b: An orthologous small heat shock protein gene in Tribolium castaneum 下载免费PDF全文
J. Xie W. Xiong X. Hu S. Gu S. Zhang S. Gao X. Song J. Bi B. Li 《Journal of Applied Entomology》2018,142(7):654-666
Small heat shock proteins (sHSPs) act as molecular chaperones and are widely distributed in all kinds of organisms. Comparative analysis revealed that an orthologous shsp was present during insect evolution. Here, hsp21.8b, one insect orthologous shsp, had been identified in Tribolium castaneum. Quantitative real‐time PCR illustrated that Tchsp21.8b was expressed in all developmental stages, along with the lowest expression at early embryonic stage and relative high expression at other stages especially in late eggs and late pupae. In the adult period, Tchsp21.8b exhibited the highest expression level in central nervous system and followed in elytron, epidermis, ovary and fat body. Moreover, it was upregulated 3.39‐fold in response to enhanced heat stress (45°C) for 4 hr but not to cold stress (4°C) and was upregulated by 1.73‐ to 1.94‐fold under ultraviolet (UV) exposure during 4–6 hr. It was also downregulated by 20.8%–41.8% under starvation in 3 days and had a “down‐up‐down” trend under the pathogen stresses. Larval RNA interference of Tchsp21.8b caused 40.6% insects mortality and reduced the oviposition amount by 66.0% and only 21.0% of the ds‐Tchsp21.8b eggs could hatch into larvae. These results suggested that as an orthologous shsp, Tchsp21.8b not only plays important roles in the growth, development and fecundity of T. castaneum but with the competence to resist the environment stresses, although the response is relatively weak compared to other hsps. Results from this study also uncovered the functions of the orthologous shsp in the development and anti‐stresses ability of T. castanuem. It provided more scientific evidence for revealing the physiological mechanisms of shsps of the insects and enhanced the capabilities to control different pests. 相似文献
868.
869.
870.
Li Gao Yuanyuan Ma Xiting Li Liping Zhang Chi Zhang Qianying Chen Chuanjiang Zhao 《Journal of cellular biochemistry》2020,121(1):93-102
Porphyromonas gingivalis, as a major pathogen of periodontitis, could rapidly adhere to and invade host gingival epithelial cells (GECs) for the induction of infection. One ATP-binding cassette (ABC) transporter gene was found to be upregulated during this infection process, however, the molecular mechanisms remain unclear. In this study, we systemically investigated the messenger RNA level changes of all ABC transporter family genes in P. gingivalis while being internalized within GECs by real-time polymerase chain reaction. We identified that two ABC transporter genes, PG_RS04465 (PG1010) and PG_RS07320 (PG1665), were significantly increased in P. gingivalis after coculturing with GECs. Mutant strains with knockout (KO) of these two genes were generated by homogenous recombination. PG_RS04465 and PG_RS07320 KO mutants showed no change in the growth of bacteria per se. Knockdown of PG_RS07320, but not PG_RS04465, caused decreased endotoxin level in the bacteria. In contrast, both mutant strains showed decreased Arg- and Lys-gingipains activities, with significantly reduced adhesion and invasion capabilities. Secreted interleukin-1β (IL-1β) and IL-6 levels in GECs cocultured with PG_RS04465 or PG_RS07320 KO mutants were also decreased, whereas, only the cells cocultured with PG_RS07320 KO mutants showed significant decrease. In addition, virulence study using mouse revealed that both KO mutant strains infection caused less mouse death than wild-type strains, showing reduced virulence of two KO strains. These results indicated that ABC transporter genes PG_RS04465 and PG_RS07320 are positive regulators of the virulence of P. gingivalis. 相似文献