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961.
Information on cadmium (Cd) uptake and transport is essential to understand better the physiology of Cd tolerance in plants.
In this study, Cd uptake, translocation, and tolerance were investigated in AHA1 (Arabidopsis plasma membrane H+-ATPase gene) overexpressed plants. Exposed to 10 μM CdCl2, AHA1OX showed a higher root elongation, accumulated more Cd, and maintained better integrity of nucleus membrane of root
tips in comparison to the control plant (WT), suggesting that AHA1OX was more Cd tolerant than WT. To investigate Cd tolerance
mechanism of AHA1OX plants, we measured the activity of plasma membrane H+-ATPase and the secretion of citrate. Results indicated that treatment with 10 μM of Cd stimulated the activity of plasma
membrane H+-ATPase and the secretion of citrate, while 30 μM of Cd inhibited them. AHA1OX had higher activity of H+-ATPase and secretion of citrate than WT. Addition of citrate enhanced root-to-shoot translocation of Cd significantly. A
higher root-to-shoot Cd translocation was observed in AHA1OX than in WT plants. Treatment with low temperature or metabolic
inhibitor (carbonyl cyanide m-chlorophenylhydrazone) inhibited Cd uptake and translocation. The study of Cd forms using sequential extraction indicated
that Cd was mainly present as a protein-bound form, and AHA1OX had more water-soluble Cd than WT. Taken together, our results
suggested that the Cd tolerance of AHA1OX was associated with its root-to-shoot Cd translocation and secretion of citrate,
which converts Cd2+ into less toxic and more easily transportable forms in plant cells. 相似文献
962.
Vedat Cinar Yahya Polat Abdulkerim Kasim Baltaci Rasim Mogulkoc 《Biological trace element research》2011,140(1):18-23
This study was performed to assess how 4 weeks of magnesium supplementation and exercise affect the free and total plasma
testosterone levels of sportsmen practicing tae kwon do and sedentary controls at rest and after exhaustion. The testosterone
levels were determined at four different periods: resting before supplementation, exhaustion before supplementation, resting
after supplementation, and exhaustion after supplementation in three study groups, which are as follows: Group 1—sedentary
controls supplemented with 10 mg magnesium per kilogram body weight. Group 2—tae kwon do athletes practicing 90–120 min/day
supplemented with 10 mg magnesium per kilogram body weight. Group 3—tae kwon do athletes practicing 90–120 min/day receiving
no magnesium supplements. The free plasma testosterone levels increased at exhaustion before and after supplementation compared
to resting levels. Exercise also increased testosterone levels relative to sedentary subjects. Similar increases were observed
for total testosterone. Our results show that supplementation with magnesium increases free and total testosterone values
in sedentary and in athletes. The increases are higher in those who exercise than in sedentary individuals. 相似文献
963.
Shi-Xiao Xu Xiao-Dong Cai Bin Tan Wen-Wu Guo 《Plant Cell, Tissue and Organ Culture》2011,104(2):199-207
The green fluorescent protein (GFP) has become an ideal visual marker to monitor and quantify the expression of the transgene.
It can be targeted to specific subcellular locations, including the endoplasmic reticulum, mitochondria, actin cytoskeleton
and nuclei through the addition of signal peptides. Our previous work has resulted in transgenic citrus plants expressing
cytoplasmic targeted GFP (Cy-GFP) or endoplasmic reticulum targeted GFP (Er-GFP) gene. To evaluate the localization of three
different subcellular targeted GFP, i.e., Cy-GFP, Er-GFP and mitochondria targeted GFP (Mt-GFP) in citrus tissues and to utilize
cell lines containing Mt-GFP for basic research in cell fusion, the plasmid pBI-mgfp4-coxIV encoding the Mt-GFP gene was successfully
transferred into embryogenic callus of Valencia sweet orange (Citrus sinensis (L.) Osbeck) via Agrobacterium tumefaciens-mediated transformation. Furthermore, we compared the specific expression of these three different subcellular localized
GFP constructs in cells of different mature leaf tissues (upper epidermis, palisade parenchyma, spongy parenchyma and lower
epidermis) by a confocal laser scanning microscope (CLSM). Cytoplasmic-localized GFP expression was observed throughout the
cytoplasm but appeared to accumulate within the nucleoplasm. The Er-GFP occurred within a layer very close to the cell wall.
In addition, a stable fluorescence on the ER network throughout the guard cells was detected. Interestingly, the Mt-GFP specifically
expressed in the guard cells to particles of about 1–2 μm within the cytoplasm in this case. To verify that the fluorescent
particles observable in the guard cells are indeed mitochondria, we co-localize the Mt-GFP fusion protein with a mitochondrial-specific
dye in citrus protoplasts. These results demonstrate that the subcellular distribution of the three subcellular targeted GFP
is very distinct in citrus leaf cells and the cell lines containing Mt-GFP gene can be further used in citrus basic cell fusion
research. 相似文献
964.
Kallnik V Schulz C Schultz C Schweiger P Deppenmeier U 《Applied microbiology and biotechnology》2011,90(4):1285-1293
The first hyperthermophilic d-arabitol dehydrogenase from Thermotoga maritima was heterologously purified from Escherichia coli. The protein was purified with and without a Strep-tag. The enzyme exclusively catalyzed the NAD(H)-dependent oxidoreduction of d-arabitol, d-xylitol, d-ribulose, or d-xylulose. A twofold increase of catalytic rates was observed upon addition of Mg2+ or K+. Interestingly, only the tag-less protein was thermostable, retaining 90% of its activity after 90 min at 85 °C. However,
the tag-less form of d-arabitol dehydrogenase had similar kinetic parameters compared to the tagged enzyme, demonstrating that the Strep-tag was not deleterious to protein function but decreased protein stability. A single band at 27.6 kDa was observed on SDS-PAGE
and native PAGE revealed that the protein formed a homohexamer and a homododecamer. The enzyme catalyzed oxidation of d-arabitol to d-ribulose and therefore belongs to the class of d-arabitol 2-dehydrogenases, which are typically observed in yeast and not bacteria. The product d-ribulose is a rare ketopentose sugar that has numerous industrially applications. Given its thermostability and specificity,
d-arabitol 2-dehydrogenase is a desirable biocatalyst for the production of rare sugar precursors. 相似文献
965.
Expression of key antioxidant enzymes under combined effect of heat and cadmium toxicity in growing rice seedlings 总被引:2,自引:0,他引:2
Effect of Cd2+ toxicity and heat stress in sensitive rice cv. DR-92 and tolerant rice cv. Bh-1 grown in North East region of India were studied in sand cultures. Increasing levels of 0–500 μM Cd2+ alone and/or heat stress showed increased activities of superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase and
glutathione reductase enzymes which were associated with induced oxidative stress and altered enzyme activities. The values
for SOD and POD activities were always more in cv. DR-92 whereas CAT and GR activities were higher in cv. Bh-1 in roots and shoots under Cd2+ or heat stress alone in sensitive cv. DR-92. Upon imposition of a combination of Cd2+ + heat the activities of SOD and POD decreased significantly in root/shoot of both the sensitive and tolerant rice varieties.
A nine fold increase in GR activity under combination of heat + 100 μM Cd2+ stress in shoots of cv. Bh-1 at day 15 was noted when compared to controls. The dual stress combination of Cd2+ + heat did not alter catalase activity in vivo in both the rice varieties. Results suggest a time-specific and varietal distribution
of the antioxidant enzymes in rice plants subjected to Cd2+ and/or heat stress. Tolerant cv. Bh-1 has better survival to combined stressors like Cd2+ and heat than sensitive rice cv. DR-92 and heat stress when given in combination with Cd2+ toxicity seem to mitigate the effect of Cd2+ stress alone in rice. The study indicates individual Cd2+ toxicity and heat stress and a combination of the two stresses to have separate implications on antioxidative defense mechanism
in rice plants. Among enzymes of the defense apparatus ascorbate peroxidase and glutathione reductase appear to serve as an
important component for better survival of rice plants under combination of Cd2+ + heat stress. 相似文献
966.
There are classes of microbial enzymes that have the ability to degrade harmful organophosphorus (OP) compounds that are present
in some pesticides and nerve agents. To date, the most studied and potentially important OP-degrading enzymes are organophosphorus
hydrolase (OPH) and organophosphorus acid anhydrolase (OPAA), which have both been characterized from a number of organisms.
Here we provide an update of what is experimentally known about OPH and OPAA to include their structures, substrate specificity,
and catalytic properties. Current and future potential applications of these enzymes in the hydrolysis of OP compounds are
also addressed. 相似文献
967.
Porro D Gasser B Fossati T Maurer M Branduardi P Sauer M Mattanovich D 《Applied microbiology and biotechnology》2011,89(4):939-948
Recombinant DNA (rDNA) technologies allow the production of a wide range of peptides, proteins and metabolites from naturally
non-producing cells. Since human insulin was the first heterologous compound produced in a laboratory in 1977, rDNA technology
has become one of the most important technologies developed in the 20th century. Recombinant protein and metabolites production
is a multi-billion dollar market. The development of a new product begins with the choice of the cell factory. The final application
of the compound dictates the main criteria that should be taken into consideration: (1) quality, (2) quantity, (3) yield and
(4) space time yield of the desired product. Quantity and quality are the most predominant requirements that must be considered
for the commercial production of a protein. Quantity and yield are the requirements for the production of a metabolite. Finally,
space time yield is crucial for any production process. It therefore becomes clear why the perfect host does not exist yet,
and why—despite important advances in rDNA applications in higher eukaryotic cells—microbial biodiversity continues to represent
a potential source of attractive cell factories. In this review, we compare the advantages and limitations of the principal
yeast and bacterial workhorse systems. 相似文献
968.
Luís Vázquez Rosario Panadero Vicente Dacal Francisco Javier Pato Ceferino López Pablo Díaz María Sol Arias Gonzalo Fernández Pablo Díez-Baños Patrocinio Morrondo 《Experimental & applied acarology》2011,53(4):399-409
During the 2007 and 2008 hunting seasons (April–October) the skin of 367 roe deer (Capreolus capreolus L.), hunted in different preserves from Galicia (Northwestern Spain), were examined for ticks (Acari: Ixodidae). The overall
prevalence of infestation by ticks was 83.1%. The predominant species was Ixodes ricinus (83.1%), whereas a single Dermacentor marginatus specimen appeared in one roe deer. All developmental stages of I. ricinus were found parasitizing roe deer, the adults being the most frequent (82.2%), followed by nymphs (45.6%) and larvae (27.2%).
The mean intensity of infestation by I. ricinus was 43.2 ± 49.85; most of them were adults (30.7 ± 31.64) and in a lesser extend nymphs (16.9 ± 24.74) and larvae (10.7 ± 29.90).
Ixodes ricinus was present all over the study with percentages that oscillated between 100% in spring and 57.4% in autumn. CHAID algorithm
showed the sex of roe deer as the most influential factor in tick prevalence, followed by the climatic area. The different
developmental stages of I. ricinus were more frequent in males than in females, and the prevalence of adults and larvae were higher in roe deer from coastal
areas than in those from mountainous and central areas, whereas nymphs were more frequent in mountainous areas. Host age and
density were not determinants for tick infestation. Our results confirm that roe deer are important hosts for I. ricinus in northwestern Spain, serving as a vehicle for the geographic distribution of these ticks. 相似文献
969.
Marie E. Herberstein Jutta M. Schneider Aaron M. T. Harmer Anne C. Gaskett Katherine Robinson Kim Shaddick Daniel Soetkamp Peter D. Wilson Stano Pekár Mark A. Elgar 《Journal of Ethology》2011,29(1):9-15
Female St Andrew’s Cross spiders control copulation duration by timing sexual cannibalism and may thereby control paternity
if cannibalism affects sperm transfer. We have investigated the effect of copulation duration on sperm transfer and documented
sperm storage patterns when we experimentally reduced the ability of females to attack and cannibalise the male. Virgin males
and females were paired and randomly allocated either to a control treatment, where females were allowed to attack and cannibalise
the male during copulation, or to an experimental treatment, where females were unable to cannibalise the male. The latter
was achieved by placing a paintbrush against her chelicerae during copulation. Our experimental manipulation did not affect
copulation duration or sperm storage. However, the number of sperm stored by the female increased with copulation duration
only if the male was cannibalised, suggesting that cannibalism increases relative paternity not only through prolonged copulation
duration following a fair raffle model but also through the cannibalism act itself. Future studies should explore whether
cannibalised males ejaculate more sperm or whether females selectively store the sperm of cannibalised males. 相似文献
970.
A hyperthermophilic heterotrophic archaeon (strain WB1) was isolated from a thermal pool in the Washburn hot spring group
of Yellowstone National Park, USA. WB1 is a coccus, 0.6–1.2 μm in diameter, with a tetragonal S-layer, vacuoles, and occasional
stalk-like protrusions. Growth is optimal at 84°C (range 64–93°C), pH 5–6 (range 3.5–8.5), and <1 g/l NaCl (range 0–4.6 g/l
NaCl). Tests of metabolic properties show the isolate to be a strict anaerobe that ferments complex organic substrates. Phylogenetic
analysis of the 16S rRNA gene sequence places WB1 in a clade of previously uncultured Desulfurococcaceae and shows it to have
≤96% 16S rRNA sequence identity to Desulfurococcus mobilis, Staphylothermus marinus, Staphylothermus hellenicus, and Sulfophobococcus zilligii. The 16S rRNA gene contains a large insertion similar to homing endonuclease introns reported in Thermoproteus and Pyrobaculum species. Growth is unaffected by the presence of S0 or SO4
2−, thereby differentiating the isolate from its closest relatives. Based on phylogenetic and physiological differences, it
is proposed that isolate WB1 represents the type strain of a novel genus and species within the Desulfurococcaceae, Thermogladius shockii gen. nov., sp. nov. (RIKEN = JCM-16579, ATCC = BAA-1607, Genbank 16S rRNA gene = EU183120). 相似文献