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991.
Organelle transport along microtubules in Xenopus melanophores: evidence for cooperation between multiple motors 下载免费PDF全文
Xenopus melanophores have pigment organelles or melanosomes which, in response to hormones, disperse in the cytoplasm or aggregate in the perinuclear region. Melanosomes are transported by microtubule motors, kinesin-2 and cytoplasmic dynein, and an actin motor, myosin-V. We explored the regulation of melanosome transport along microtubules in vivo by using a new fast-tracking routine, which determines the melanosome position every 10 ms with 2-nm precision. The velocity distribution of melanosomes transported by cytoplasmic dynein or kinesin-2 under conditions of aggregation and dispersion presented several peaks and could not be fit with a single Gaussian function. We postulated that the melanosome velocity depends linearly on the number of active motors. According to this model, one to three dynein molecules transport each melanosome in the minus-end direction. The transport in the plus-end direction is mainly driven by one to two copies of kinesin-2. The number of dyneins transporting a melanosome increases during aggregation, whereas the number of active kinesin-2 stays the same during aggregation and dispersion. Thus, the number of active dynein molecules regulates the net direction of melanosome transport. The model also shows that multiple motors of the same polarity cooperate during the melanosome transport, whereas motors of opposite polarity do not compete. 相似文献
992.
Evidence of DNA replication in an arbuscular mycorrhizal fungus in the absence of the host plant 总被引:1,自引:0,他引:1
Summary This study provides evidence thatGigaspora margarita replicates its nuclear DNA, even in the absence of a host plant. Three experimental approaches were used: (i) static cytofluorimetry to quantify the DNA content, (ii) pulse treatments with bromodeoxyuridine (BrdU), which is an analogue of thymidine, to reveal nuclei undergoing DNA synthesis, and (iii) ultrastructural observations to study changes in chromatin morphology during the fungal cell cycle. A slight second peak of approximately twice the value of a major peak was found by cytofluorimetry, showing that a small number of nuclei had entered in cycle during in vitro development. Nuclei which had incorporated BrdU were observed after pulses of 24 h; nuclei with condensed chromatin were also apparent at this time. The results demonstrate thatG. margarita has all the metabolic pathways needed to replicate its nuclear DNA even in the absence of the host, suggesting that more complex mechanisms inhibit the extended growth in vitro of arbuscular mycorrhizal fungi.Abbreviations AM-fungi
arbuscular mycorrhizal fungi
- A.U.
arbitrary units
- BrdU
5-bromo-2-deoxyuridine
- DAPI
4,6-diamidino-2-phenylindole
- UV
ultraviolet light 相似文献
993.
R De Luca A Renzulli M R Cafaro A Officioso R D'Alessandro C Sellitto V Di Donna 《Bollettino della Società italiana di biologia sperimentale》1984,60(4):745-748
In this research we have determined the behaviour of hypophisary hormones determined by radioimmunoassay. We have noted a constant increase of GH and HPrL. In one case we have seen also the decrease of LH and FSH. This changes are determined by the large dose of heparin necessary during C.E.C. 相似文献
994.
Sofia M Efremova Valeria B Itskovich Valentina Parfenova Valentin V Drucker Werner E G Müller Heinz C Schr?der 《Cellular and molecular biology, including cyto-enzymology》2002,48(4):359-371
Lake Baikal is considered as a unique place to study evolution. In this review, we report on recent data on the evolution of endemic freshwater sponges of this ancient lake. Nucleotide sequence data support the idea that these sponges are of monophyletic origin and evolved from Spongillidae. Baikalian sponges form the dominating biomass in the benthos of the lake. Data on the expression of the biomarker heat shock protein 70, revealed that the endemic sponge species of Lake Baikal are useful as bioindicators to assess the anthropogenic impact on the lake. 相似文献
995.
Cuprizone affects the liver of treated mice in a random manner, causing no appreciable change in some cases and inducing the formation of megamito-chondria with altered properties in others. Lack of a full appreciation of this variability may be at the origin of some discrepancies in published work dealing with the properties of cuprizone mouse liver mitochondria (CMLM). CMLM from fully affected livers were remarkably labile and difficult to isolate in a coupled state by homogenization and centrifugation techniques. The integral respiratory chain proteins of CMLM were functionally normal, with the exception of succinic dehydrogenase which showed considerable inhibition. Coupled morphological and functional analysis provided evidence that these properties were independent of CMLM size, a matter which had remained doubtful thus far and bears on the validity of literature reports.Abbreviations MLM
mouse liver mitochondria
- CMLM
cuprizone mouse liver mitochondria
- PMS
phenazine methosulfate
- Mops
4-morphoinopropanesulfonic acid
- TMPD
tetramethyl-p-phenylenediamine
- AA
Antimycin A
- RCR
respiratory control ratio
- BSA
bovine serum albumin 相似文献
996.
Roberto Mrquez Valeria Ramírez‐Castaeda Adolfo Amzquita 《Evolution; international journal of organic evolution》2019,73(2):390-400
Toxicity is widespread among living organisms, and evolves as a multimodal phenotype. Part of this phenotype is the ability to avoid self‐intoxication (autoresistance). Evolving toxin resistance can involve fitness tradeoffs, so autoresistance is often expected to evolve gradually and in tandem with toxicity, resulting in a correlation between the degrees of toxicity and autoresistance among toxic populations. We investigate this correlation in Phyllobates poison frogs, notorious for secreting batrachotoxin (BTX), a potent neurotoxin that targets sodium channels, using ancestral sequence reconstructions of BTX‐sensing areas of the muscular voltage‐gated sodium channel. Reconstructions suggest that BTX resistance arose at the root of Phyllobates, coinciding with the evolution of BTX secretion. After this event, little or no further evolution of autoresistance seems to have occurred, despite large increases in toxicity throughout the history of these frogs. Our results, therefore, provide no evidence in favor of an evolutionary correlation between toxicity and autoresistance, which conflicts with previous work. Future research on the functional costs and benefits of mutations putatively involved in BTX resistance, as well as their prevalence in natural populations, should shed light on the evolutionary mechanisms driving the relationship between toxicity and autoresistance in Phyllobates frogs. 相似文献
997.
998.
De Laurentiis Valeria Hunt Dexter V. L. Lee Susan E. Rogers Christopher D. F. 《The International Journal of Life Cycle Assessment》2019,24(7):1222-1238
The International Journal of Life Cycle Assessment - This paper describes the research that underpins the development of EATS (the Environmental Assessment Tool for School meals), a life... 相似文献
999.
Spampinato Mariarita Sferrazzo Giuseppe Pittalà Valeria Di Rosa Michelino Vanella Luca Salerno Loredana Sorrenti Valeria Carota Giuseppe Parrinello Nunziatina Raffaele Marco Tibullo Daniele Li Volti Giovanni Barbagallo Ignazio 《Molecular biology reports》2020,47(3):1949-1964
Molecular Biology Reports - Non-small cell lung cancer (NSCLC) remains the leading cause of cancer-related death mainly due to its high metastatic rate. Impairment of redox homeostasis mechanisms... 相似文献
1000.