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111.
High concentrations of heavy metals are known to be toxic to many soil organisms. The effects of long-term exposure to lower levels of metals on the soil microbial community are, however, less well understood. The southern Pennines of the U.K. are characterised by expanses of ombrotrophic peat soils that have experienced deposition of high levels of heavy metals since the mid to late 1800s. Concentrations of metals in the peat remain high but the effect of the contamination on the in-situ microbial communities is unknown. Geochemical and molecular polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and sequencing techniques were used to derive new information on the metal chemistry and microbial populations in peat soils from six locations in the southern Pennines. All sites were highly acidic (pH 3.00–3.14) with high concentrations of potentially toxic heavy metals, particularly porewater Zn and particulate-associated Pb. The results also reveal a split in site characteristics between the most polluted sites with the highest levels of bioavailable metals (Bleaklow, FeatherBed Moss and White Hill) and those with much lower bioavailable metals (Cowms Moor, Holme Moss and Round Hill). There was no difference in the number of dominant bacterial species between the sites but there were significant differences in the species composition. At the three sites with the highest levels of bioavailable metals, bacterial species with a high similarity to acidophilic sulphur- and iron-oxidizing bacteria and those from high metal environments were detected. The transformations carried out by these metal mobilising and acid producing bacteria may make heavy metals more bioavailable and therefore more toxic to higher organisms. Bacteria with similarity to those typically found in forest and grassland soils were documented at the three sites with the lowest levels of bioavailable metals. The data highlight the need for further studies to elucidate the species diversity and functionality of bacteria in heavy metal contaminated peats in order to assess implications for moorland restoration.  相似文献   
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Results from examining shellfish collected from ‘safe’ (2–34Escherichia coli/100 mL) and ‘unsafe’ (> 34E. coli/100 mL) waters for the presence ofYersinia enterocolitica and related bacteria are reported. The recovery of these microorganisms was low in bivalve mollusks destined for food consumption, high in those derived from prohibited areas. No human pathogenic bio-serogroup f Yersinia was found during the entire survey.  相似文献   
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Archaeologists often encounter problems in interpreting the genesis of layers and the context in which specific materials occur in excavations. Field visits of geologists, soil scientists or biologists can solve a number of questions, but often, problems remain that only can be studied by microscopic research as, for example, soil micromorphology and palynology. In the past, the employment of these two disciplines, one in earth science and one in biology, generally occurred independently of each other, also in interdisciplinary research and contract research. Consequently, results could not always be correlated, permitting only a restricted integration of data. It was realised that soils, as archives, contain much more information than generally utilised. A skillful employment and balancing of both specialties create a real integrated approach that offers a substantially improved interpretation potential without hardly additional efforts and costs. The results of 7 years of experience were very stimulating and presented here.In this article, the essence of soil micromorphology and palynology applied to archaeology is briefly outlined and illustrated by selected examples of the different research themes covered, showing the possibilities and results of integrated research. Both specialties generate essential information that, when combined and integrated properly, lead to improved understanding of the landscape genesis and human activities in the past. To be able to employ the full interpretive potential of this integrated approach, the research procedures followed by both specialties had to be compared. The key requirements for optimal integration of each other's databases comprised a combined effort to compare the pros and cons during the first four steps of the research procedure: defining research questions, field survey, selection of sampling locations and sampling. This approach enabled optimal correlation of the individual results, made cross-checking and references possible and led to higher levels of interpretation that would not have been possible otherwise. The integrated research elucidated lacunae in the other's discipline, resulting in a distinctly more complete reconstruction of paleoenvironments and past land uses, important research themes of archaeologists for the specialties concerned.  相似文献   
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Much of the genetic predisposition to colorectal cancer (CRC) in humans is unexplained. Studying a Caucasian-dominated population in the United States, we showed that germline allele-specific expression (ASE) of the gene encoding transforming growth factor-beta (TGF-beta) type I receptor, TGFBR1, is a quantitative trait that occurs in 10 to 20% of CRC patients and 1 to 3% of controls. ASE results in reduced expression of the gene, is dominantly inherited, segregates in families, and occurs in sporadic CRC cases. Although subtle, the reduction in constitutive TGFBR1 expression alters SMAD-mediated TGF-beta signaling. Two major TGFBR1 haplotypes are predominant among ASE cases, which suggests ancestral mutations, but causative germline changes have not been identified. Conservative estimates suggest that ASE confers a substantially increased risk of CRC (odds ratio, 8.7; 95% confidence interval, 2.6 to 29.1), but these estimates require confirmation and will probably show ethnic differences.  相似文献   
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The deepening U.S. farm crisis has been accompanied by numerous benefit fund raisers, individual donations and volunteer programs—all an expression of cooperation and concern on the part of U.S. citizens, farmer and non-farmer alike. These responses have received wide media attention and much public praise. A sense of patriotism and self-reliance underlies their popularity. Nevertheless, such efforts work to undermine their own ultimate objective—that of improving the economic circumstances of the family farm and farm family. This irony, it is argued, arises from the fact that these charitable responses typically depoliticize the nature of the U.S. farm crisis. First, they deflect public attention away from the larger economic context and the structural inequities within it. Second they revitalize agrarian-based myths which serve to rationalize and to reproduce the ‘independent’ behavior of small, commercial farmers. Finally, it is argued that the depoliticization of the farm crisis is itself a political strategy, one which supports and legitimizes ‘business as usual’ and is compatible with the interests of corporate agriculture.  相似文献   
119.
We report the design and total chemical synthesis of "synthetic erythropoiesis protein" (SEP), a 51-kilodalton protein-polymer construct consisting of a 166-amino-acid polypeptide chain and two covalently attached, branched, and monodisperse polymer moieties that are negatively charged. The ability to control the chemistry allowed us to synthesize a macromolecule of precisely defined covalent structure. SEP was homogeneous as shown by high-resolution analytical techniques, with a mass of 50,825 +/-10 daltons by electrospray mass spectrometry, and with a pI of 5.0. In cell and animal assays for erythropoiesis, SEP displayed potent biological activity and had significantly prolonged duration of action in vivo. These chemical methods are a powerful tool in the rational design of protein constructs with potential therapeutic applications.  相似文献   
120.
RNA polymerase II (Pol II) transcribes genes that encode proteins and noncoding small nuclear RNAs (snRNAs). The carboxyl-terminal repeat domain (CTD) of the largest subunit of mammalian RNA Pol II, comprising tandem repeats of the heptapeptide consensus Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7, is required for expression of both gene types. We show that mutation of serine-7 to alanine causes a specific defect in snRNA gene expression. We also present evidence that phosphorylation of serine-7 facilitates interaction with the snRNA gene-specific Integrator complex. These findings assign a biological function to this amino acid and highlight a gene type-specific requirement for a residue within the CTD heptapeptide, supporting the existence of a CTD code.  相似文献   
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