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51.
Average height of the free population in the United States born in the mid-1830s began to decline despite growing per capita incomes. Explanations for this "antebellum puzzle" revolve around a possibly deteriorating disease environment promoted by urban agglomeration and increases in the relative price of protein-rich foods. However, several groups were immune to the effect, including members of the middle class, whose income was high enough, and increased enough to overcome the adverse developments and maintain their nutritional status. Although at the opposite end of the social spectrum, the height of male slaves also increased, as it was in their owners' interest to raise their slaves' food allotments. The height of Tennessee convicts, analyzed in this article, also increased in the late-1830s, being the third exception to the "antebellum puzzle." Mid-19th century Tennessee was integrated into interstate commerce in cotton and tobacco and experienced considerable movement of people who would have brought with them diseases from elsewhere, hence, it would have been integrated into the US disease pool, and the fact that heights did not decline in the 1830s is therefore an indication that the antebellum puzzle cannot be explained exclusively by the spread of diseases. Yet, Tennessee's economy was quite different to that of the rest of the country. Although it did export live swine to the South, these exports did not increase during the antebellum decades. Hence, Tennessee remained self-sufficient in pork, and consumption of pork did not decline. Thus, the evidence presented here is consistent with the economic interpretation of the "antebellum puzzle": self-sufficiency in protein production protected even the members of the lower-classes of Tennessee from the negative externalities associated with the onset of industrialization.  相似文献   
52.
Very-long-chain fatty acids (VLCFAs) are essential for many aspects of plant development and necessary for the synthesis of seed storage triacylglycerols, epicuticular waxes, and sphingolipids. Identification of the acetyl-CoA carboxylase PASTICCINO3 and the 3-hydroxy acyl-CoA dehydratase PASTICCINO2 revealed that VLCFAs are important for cell proliferation and tissue patterning. Here, we show that the immunophilin PASTICCINO1 (PAS1) is also required for VLCFA synthesis. Impairment of PAS1 function results in reduction of VLCFA levels that particularly affects the composition of sphingolipids, known to be important for cell polarity in animals. Moreover, PAS1 associates with several enzymes of the VLCFA elongase complex in the endoplasmic reticulum. The pas1 mutants are deficient in lateral root formation and are characterized by an abnormal patterning of the embryo apex, which leads to defective cotyledon organogenesis. Our data indicate that in both tissues, defective organogenesis is associated with the mistargeting of the auxin efflux carrier PIN FORMED1 in specific cells, resulting in local alteration of polar auxin distribution. Furthermore, we show that exogenous VLCFAs rescue lateral root organogenesis and polar auxin distribution, indicating their direct involvement in these processes. Based on these data, we propose that PAS1 acts as a molecular scaffold for the fatty acid elongase complex in the endoplasmic reticulum and that the resulting VLCFAs are required for polar auxin transport and tissue patterning during plant development.  相似文献   
53.
Chromatophore organs are complex and unique structures responsible for the variety of body coloration patterns used by cephalopods to communicate and camouflage. They are formed by a pigment-containing cytoelastic sacculus, surrounded by muscle fibers directly innervated from the brain. Muscle contraction and relaxation are responsible for expansion and retraction of the pigment-containing cell. Their functioning depends on glutamate and Phe-Met-Arg-Phe-NH2-related peptides, which induce fast and slow cell expansion, respectively, and 5-hydroxytryptamine, which induces retraction. Apart from these three substances and acetylcholine, which acts presynaptically, no other neuroactive compounds have so far been found to be involved in the neuroregulation of chromatophore physiology, and the detailed signaling mechanisms are still little understood. Herein, we disclose the role of nitric oxide (NO) as mediator in one of the signaling pathways by which glutamate activates body patterning. NO and nitric-oxide synthase have been detected in pigment and muscle fibers of embryo, juvenile, and adult chromatophore organs from Sepia officinalis. NO-mediated Sepia chromatophore expansion operates at slower rate than glutamate and involves cGMP, cyclic ADP-ribose, and ryanodine receptor activation. These results demonstrate for the first time that NO is an important messenger in the long term maintenance of the body coloration patterns in Sepia.  相似文献   
54.
Deposition of amphiphilic porphyrin derivatives occurs spontaneously on silanised glass surfaces, in a controlled fashion. The resulting porphyrin films show appreciable fluorescence emission. This emission can be effectively quenched by immersion of the slides into a diluted solution of Hg(2+) (microM concentration). The initial intensity can be restored by washings with a solution of N,N,N',N'-tetrakis(2-pyridilmethyl)ethylenediammine with no loss of efficiency. A remarkable selectivity is featured toward the detection of Hg(2+) over Cu(2+), Cd(2+), Pb(2+) and Zn(2+) counterparts. This protocol can be extended to a flow-through apparatus. The presented results are of importance for the achievement of a solid-state chemosensor for mercuric ions, at micromolar concentration, in water.  相似文献   
55.
Prey animals must balance antipredatory behaviour with foraging behaviour. According to the risk allocation hypothesis, prey increase antipredatory behaviour and reduce foraging activity during pulses of high risk, but with continuous risk, other activities must continue and antipredatory behaviour decreases despite the risk. We studied the impact of lynx presence on the vigilance behaviour of wild roe deer under conditions of (i) a pulsed elevated risk by experimentally spreading lynx urine as an olfactory cue, and (ii) continuous risk by comparing an area where lynx was eradicated 160 years ago to an area where lynx has been re‐introduced 30 years ago. Roe deer were extremely vigilant in response to the predator olfactory cue; however, roe deer vigilance did not differ measurably among areas with or without potential lynx presence. Deer were more vigilant before sunset than during the night at both study areas, probably due to long‐term adaptation of roe deer to human hunting during daytime. Vigilance decreased from August to September even though activity of lynx increases in autumn, which may be a result either of increased foraging due to decrease in food quality in autumn, or of changes in social organization of the deer. Our results suggested that the degree of vigilance depends on environmental cues. We found that roe deer respond to lynx urine despite a long absence of lynx in the ecosystem. Our results support the risk allocation hypothesis for responses to pulses of high risk but not for responses to continuous elevated levels of risk.  相似文献   
56.
The mechanism for generating double minutes chromosomes (dmin) and homogeneously staining regions (hsr) in cancer is still poorly understood. Through an integrated approach combining next-generation sequencing, single nucleotide polymorphism array, fluorescent in situ hybridization and polymerase chain reaction-based techniques, we inferred the fine structure of MYC-containing dmin/hsr amplicons harboring sequences from several different chromosomes in seven tumor cell lines, and characterized an unprecedented number of hsr insertion sites. Local chromosome shattering involving a single-step catastrophic event (chromothripsis) was recently proposed to explain clustered chromosomal rearrangements and genomic amplifications in cancer. Our bioinformatics analyses based on the listed criteria to define chromothripsis led us to exclude it as the driving force underlying amplicon genesis in our samples. Instead, the finding of coexisting heterogeneous amplicons, differing in their complexity and chromosome content, in cell lines derived from the same tumor indicated the occurrence of a multi-step evolutionary process in the genesis of dmin/hsr. Our integrated approach allowed us to gather a complete view of the complex chromosome rearrangements occurring within MYC amplicons, suggesting that more than one model may be invoked to explain the origin of dmin/hsr in cancer. Finally, we identified PVT1 as a target of fusion events, confirming its role as breakpoint hotspot in MYC amplification.  相似文献   
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Scuba diving is now one of the major form of commercial use of marine protected areas (MPAs) around the world and the control of its potential impacts on the marine environment represents a fundamental key to manage this recreational activity in highly dived areas. A potential tool to tackle such issues has been thought to be the definition of a value of recreational carrying capacity of an area, but this approach has been rarely considered management-effective. Therefore, the first step for effectively managing scuba-diving should be ‘bottom-up’: characterizing the benthic communities potentially affected by diving and evaluating their vulnerability. Aim of this paper is to propose a tool to define an index of vulnerability for dive trails (STVI: scuba trail vulnerability index). This has taken into consideration both physical and biological features of each trail. All the considered features are represented by non-quantitative variables, because either they are purely qualitative or their quantitative measurement is impractical. The management of such qualitative information and its translation into a formal methodology was performed by means of fuzzy logic, which has been repeatedly proposed as a powerful technique to develop indices of environmental quality. The approach adopted in this study provided a useful tool for the preliminary assessment of the potential vulnerability of benthic assemblages to scuba-diving and may represent an alternative method to the assessment of carrying capacity. The application of this index will enable management strategies for potentially reducing the degradation of benthic organisms/assemblages, and allowing a sustainable use of MPAs.  相似文献   
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