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81.
The response to high concentrations of B in soil was compared for Triticum aestivum L. (vars. Chinese Spring and Halberd) and the amphiploid of Chinese Spring × Agropyron elongatum (Host). The tolerance of the three genotypes, with respect to yield at the high B treatments, was amphipolid>Halberd>Chinese Spring. The concentration of B in whole shoots was similar for the amphiploid and Halberd and significantly higher for Chinese Spring. The mechanism for tolerance to B appears to be the same for the amphiploid and wheat and is related to reduced accumulation of B in shoots. 相似文献
82.
Seedlings of two cultivars of wheat (Triticum aestivum L.) differing in tolerance to aluminium (Al) were grown using a split-root sand/soil culture technique. Each culture tube
was divided horizontally into a surface (0–150 mm) compartment and a subsurface (150–250 mm) compartment separated by a root-permeable
paraffin wax barrier. Thus phosphorus (P) supplied to surface roots could not percolate or diffuse into the soil in the subsurface
compartment. The soil in the subsurface compartment was divided into ‘rhizosphere’ and ‘non-rhizosphere’ zones using a porous
(5 μm) membrane.
Root growth of both cultivars into the subsurface zone was enhanced by increased P supply to surface roots, but did not conform
to known relationships between root growth and soil pH, extractable-Al, or pH, Al or P concentrations in soil solution. Concentrations
of Al in soil solution in the rhizosphere were greater than those in solution in the bulk soil. Concentrations of Al reactive
with pyrocatechol violet (30s-RRAI) in the rhizosphere soil solution were generally greater than those in non-rhizosphere
soil. With the Al-sensitive cultivar, root dry weight and length increased as concentrations of RRAl in the rhizosphere soil
solution increased. Increased concentrations of Al in rhizosphere soil solutions were not related to the presence of organic
ligands in solution.
The effect of P in promoting root penetration into the acidic subsurface stratum was not related to differential attainment
of maturity by the plant shoots, but appeared to be related to the effect of P in enhancing the rate of root growth. Thus,
suboptimal supply of P to the surface roots of a plant, even at levels sufficient to preclude development of nutritional (P)
stress symptoms, may seriously reduce tolerance to Al, and hence diminish the ability of roots to penetrate into acidic subsoils. 相似文献
83.
The physiological basis of plant reaction to and tolerance of aluminium (Al) is poorly understood. We review the results of
investigations into Al toxicity and root physiology to develop a theoretical basis for explaining the reaction of the root
to Al, including suggested roles for Ca2+, mucilaginous cap secretions and endogenous growth regulators in mediating a transmitted response between Al-damaged cap
cells and the interacting cell populations of the cap and root.
This information is used to identify possible mechanisms of Al tolerance, notably involving signal transduction, Al uptake
pathways and root morphogenesis; and to briefly discuss how procedures selecting for Al tolerance may be improved by incorporating
the concept of stimulus-response coupling.
Similarities in the responses of roots to Al and other signals (e.g. gravity, light, mechanical impedance) are used to develop the hypothesis that roots respond to environmental signals by way
of a common regulatory system. New research prospects for extending our perception of Al tolerance mechanisms are identified. 相似文献
84.
Nicole Benhamou Pierre J. Lafontaine Dominique Mazau Marie-Thérèse Esquerré-Tugayé 《Planta》1991,184(4):457-467
An antiserum raised against deglycosylated hydroxyproline-rich glycoproteins (HPGPs) from melon (Cucumis melo L.) was used to study the relationship between Rhizobium infection and induction of HRGPs in bean (Phaseolus vulgaris L.) root nodule cells infected with either the wild-type or a C4-dicarboxylic acid mutant strain of Rhizobium leguminosarum bv. phaseoli. In effective nodules, where fixation of atmospheric dinitrogen is taking place, HRGPs were found to accumulate mainly in the walls of infected cells and in peribacteroid membranes surrounding groups of bacteroids. Internal ramifications of the peribacteroid membrane were also enriched in HRGPs whereas the peribacteroid space as well as the bacteroids themselves were free of these glycoproteins. In mutant-induced root nodules, HRGPs were specifically associated with the electron-dense, laminated structures formed in plastids as a reaction to infection by this mutant. The presence of HRGPs was also detected in the host cytoplasm. The aberrant distribution of HRGPs in infected cells of mutant-induced nodules likely reflects one aspect of the altered host metabolism in relation to peribacteroid-membrane breakdown. The possibility that the antiserum used for HRGP localization may have cross-reacted with ENOD 2 gene products is discussed in relation to amino-acid sequences and sites of accumulation. 相似文献
85.
Cold acclimation and cold-regulated gene expression in ABA mutants of Arabidopsis thaliana 总被引:22,自引:0,他引:22
We have examined the cold-induced enhancement of freezing tolerance and expression of cold-regulated (cor) genes in Arabidopsis thaliana (L.) Heynh (Landsberg erecta) and abscisic acid (ABA)-deficient (aba) and ABA-insensitive (abi) mutants derived from it. The results indicate that the abi mutations had no apparent effect on freezing tolerance, while the aba mutations did: cold-acclimated aba mutants were markedly impaired in freezing tolerance compared to wild-type plants. In addition, it was observed that non-frozen leaves from both control and cold-treated aba mutant plants were more ion-leaky than those from corresponding wild-type plants. These data are consistent with previous observations indicating that ABA levels can affect freezing tolerance. Whether ABA has a direct role in the enhancement of freezing tolerance that occurs during cold acclimation, however, is uncertain. Several studies have suggested that ABA might mediate certain changes in gene expression that occur during cold acclimation. Our data indicate that the ABA-induced expression of three ABA-regulated Arabidopsis cor genes was unaffected in the abi2, abi3, and aba-1 mutants, but was dramatically impaired in the abi1 mutant. Cold-regulated expression of all three cor genes, however, was nearly the same in wild-type and abi1 mutant plants. These data suggest that the cold-regulated and ABA-regulated expression of the three cor genes may be mediated through independent control mechanisms. 相似文献
86.
Expression and stability of amplified genes encoding 5-enolpyruvylshikimate-3-phosphate synthase in glyphosate-tolerant tobacco cells 总被引:10,自引:0,他引:10
Yunxia Wang James D. Jones Stephen C. Weller Peter B. Goldsbrough 《Plant molecular biology》1991,17(6):1127-1138
Two distinct cDNAs for 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) were obtained from a glyphosate-tolerant tobacco cell line. The cDNAs were 89% identical and the predicted sequences of the mature proteins were greater than 83% identical with EPSPS proteins from other plants. Tobacco EPSPS proteins were more similar to those from tomato and petunia than Arabidopsis. One cDNA clone, EPSPS-1, represented a gene that was amplified in glyphosate-tolerant cells, while the gene for EPSPS-2 was unaltered in these cells. Consequently, EPSPS-1 mRNA was more abundant in tolerant than unselected cells, whereas EPSPS-2 mRNA was at relatively constant levels in these cell lines. Exposure of unselected cells and tobacco leaves to glyphosate produced a transient increase in EPSPS mRNA. However, glyphosate-tolerant cells containing amplified copies of EPSPS genes did not show a similar response following exposure to glyphosate. A significant proportion of the EPSPS gene amplification was maintained when tolerant cells were grown in the absence of glyphosate for eight months. Plants regenerated from these cells also contained amplified EPSPS genes. 相似文献
87.
An alternative procedure to obtain the parameters of Monod's growth model in batch culture is presented. It is based on the integral kinetic analysis methodology, employs a one-dimensional Golden Section search optimization method and is implemented on a spread-sheet programme. The procedure is discussed in detail and is illustrated by analysis of batch substrate consumption data by an aerobic bacterial consortium. 相似文献
88.
湘中、湘东地区早籼稻耐土壤潜育性评价 总被引:2,自引:0,他引:2
我国南方稻区的主要低产稻田是潜育性稻田,约有一亿亩。挖掘其“潜在生产力”,种植耐潜育性土壤逆境胁迫能力较强的水稻品种,则是简便、经济而有效的重要途径之一。本文就几个早籼稻品种(组合)对潜育性稻田的生态适应性进行了较系统的观测,并初步提出了耐潜育性的几个鉴定指标,诸如根系生长量和幼穗分化期根系氧化力;分蘖早期茎蘖增长速率;分蘖后期单株干物质产量;乳熟期剑叶片过氧化氢酶活性GDI和光合强度等。上述鉴定指标,综合应用于水稻品种生态适应性和耐潜育性育种研究,有助于提高水稻抗逆性育种的效率。 相似文献
89.
Ding W. Wu John G. Duman Chi-Hing C. Cheng Francis J. Castellino 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1991,161(3):271-278
Summary Four antifreeze proteins (AFPs) were purified from larvae of the beetle Dendroides canadensis. The AFPs are similar in amino acid compositions, having high contents of hydrophilic amino acids (45–55 mol%) and cysteine (16 mol% Cys). Approximately half of the Cys residues form disulfide bridges, and both the disulfide bridges and free sulfhydryls are essential for activity. The N-terminals of the AFPs are blocked. The pH optimum of the AFPs is 7.8, but major loss of activity occurred only at very high pH (12.0). The detergents SDS and Triton X-100 did not inactivate the AFPs. Circular dichroism spectra indicate the presence of both and secondary structures in the AFPs, in addition to a large random structure component.Abbreviations
AFP
antifreeze protein
-
CD
circular dichroism
-
DTT
dithiothreitol
-
HPLC
high pressure liquid chromatography
-
PAGE
polyacrylamide gel electrophoresis
-
PAS
periodic acid Schiff
-
SDS
sodium dodecyl sulfate
-
TFA
trifluoroacetic acid 相似文献
90.
Ding Wen Wu John G. Duman 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1991,161(3):279-283
Summary Purified antifreeze proteins (AFPs) from the larvae of the beetle Dendroides canadensis do not produce the high levels of antifreeze activity seen in the hemolymph of overwintering larvae, even when the purified AFPs are assayed at very high concentrations. However, addition of certain proteins or agar (at concentrations sufficiently low that the gel state does not result) to the Dendroides AFP resulted in a 2–3-fold increase in activity. A 70-kDa protein with AFP-activating capabilities was purified from Dendroides larvae. Addition of this endogenous activator protein to a 4 mg·ml-1 solution of AFP increased the activity of the AFPs to values comparable to those of the hemolymph of overwintering larvae. Data derived from a modified immunoblot technique demonstrate that the activators bind to the AFP, or vice versa. Formation of this association must allow the AFP to block ice crystal growth by binding to the surface of potential seed crystals in the normal fashion. However, because the AFP-activator complex is much larger than the AFP alone, the complex probably blocks a greater surface area of the crystal and is thus a more efficient antifreeze.Abbreviations
AFP
antifreeze protein
-
BSA
bovine serum albumine
-
DEAE
diethylaminoethyl
-
Ig
immunoglubolin
-
LPIN
lipoprotein ice nucleator
-
PIN
protein ice nucleator
-
SDS
sodium dodecyl sulfate
-
PAGE
polyacrylamide gel electrophoresis
-
TH
thermal hysteresis 相似文献