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1.
The species composition of aquatic insects in theboreal stream, Skiftesåa, was investigated usingemergence traps, Malaise traps and kick samples. Atleast 13 Ephemeroptera, 16 Plecoptera, 25 Trichopteraand 120 Chironomidae species were recorded. This faunais representative for non-polluted, northern streams.The production of macrobenthos was estimated to beonly about 1 g dry weight per year and m2,possibly due to the fluctuating flow of water. 相似文献
2.
Hans-Peter Hanssen 《Phytochemistry》1982,21(5):1159-1160
Several sesquiterpene hydrocarbons, mainly of the cadinane skeleton, have been identified in cultures of the brown rot fungus Lentinus lepideus. The main compounds are δ-cadinene, α- and γ-muurolene. 相似文献
3.
4.
Litman GW; Rast JP; Shamblott MJ; Haire RN; Hulst M; Roess W; Litman RT; Hinds- Frey KR; Zilch A; Amemiya CT 《Molecular biology and evolution》1993,10(1):60-72
Immunoglobulins are encoded by a large multigene system that undergoes
somatic rearrangement and additional genetic change during the development
of immunoglobulin-producing cells. Inducible antibody and antibody-like
responses are found in all vertebrates. However, immunoglobulin possessing
disulfide-bonded heavy and light chains and domain-type organization has
been described only in representatives of the jawed vertebrates. High
degrees of nucleotide and predicted amino acid sequence identity are
evident when the segmental elements that constitute the immunoglobulin gene
loci in phylogenetically divergent vertebrates are compared. However, the
organization of gene loci and the manner in which the independent elements
recombine (and diversify) vary markedly among different taxa. One striking
pattern of gene organization is the "cluster type" that appears to be
restricted to the chondrichthyes (cartilaginous fishes) and limits
segmental rearrangement to closely linked elements. This type of gene
organization is associated with both heavy- and light-chain gene loci. In
some cases, the clusters are "joined" or "partially joined" in the germ
line, in effect predetermining or partially predetermining, respectively,
the encoded specificities (the assumption being that these are expressed)
of the individual loci. By relating the sequences of transcribed gene
products to their respective germ-line genes, it is evident that, in some
cases, joined-type genes are expressed. This raises a question about the
existence and/or nature of allelic exclusion in these species. The
extensive variation in gene organization found throughout the vertebrate
species may relate directly to the role of intersegmental
(V<==>D<==>J) distances in the commitment of the individual
antibody-producing cell to a particular genetic specificity. Thus, the
evolution of this locus, perhaps more so than that of others, may reflect
the interrelationships between genetic organization and function.
相似文献
5.
The breeding performance of captive willow ptarmigan on different diets has been studied. The nutritional factors tested were protein concentration, natural feed supplement and grass meal and flavonoid admixture, and effects on egg numbers, fertility, hatchability, chick weights at hatching and 0–14 days mortality have been recorded. The breeding performance of ptarmigan hen in captivity showed great individual variations. Egg numbers were not statistically different in groups fed the different diets. Hens fed a 15 % crude protein died tended to produce smaller chicks with significantly lower viability than chicks from hens fed a 20 % crude protein diet. Supplement of natural feed tended to increase the number of chicks hatched through a combination of tendency to higher egg numbers and improved fertility. These tendencies were, however, statistically nonsignificant. Inclusion of 34 % grass meal to the diet also tended (non-significantly) to improve fertility and hatchability, while inclusion of flavonoids had no positive effect on reproduction. Eggs from captive hens showed significantly lower fertility, and a tendency to lower hatchability than eggs from wild hens. The former difference was probably caused by the close cage confinements for the captive ptarmigan, while the latter condition probably was due to different start of incubation, most of the eggs from wild hens being started naturally. 相似文献
6.
Lipopolysaccharide-activated B cells down-regulate Th1 immunity and prevent autoimmune diabetes in nonobese diabetic mice. 总被引:10,自引:0,他引:10
J Tian D Zekzer L Hanssen Y Lu A Olcott D L Kaufman 《Journal of immunology (Baltimore, Md. : 1950)》2001,167(2):1081-1089
B cells can serve dual roles in modulating T cell immunity through their potent capacity to present Ag and induce regulatory tolerance. Although B cells are necessary components for the initiation of spontaneous T cell autoimmunity to beta cell Ags in nonobese diabetic (NOD) mice, the role of activated B cells in the autoimmune process is poorly understood. In this study, we show that LPS-activated B cells, but not control B cells, express Fas ligand and secrete TGF-beta. Coincubation of diabetogenic T cells with activated B cells in vitro leads to the apoptosis of both T and B lymphocytes. Transfusion of activated B cells, but not control B cells, into prediabetic NOD mice inhibited spontaneous Th1 autoimmunity, but did not promote Th2 responses to beta cell autoantigens. Furthermore, this treatment induced mononuclear cell apoptosis predominantly in the spleen and temporarily impaired the activity of APCs. Cotransfer of activated B cells with diabetogenic splenic T cells prevented the adoptive transfer of type I diabetes mellitus (T1DM) to NOD/scid mice. Importantly, whereas 90% of NOD mice treated with control B cells developed T1DM within 27 wk, <20% of the NOD mice treated with activated B cells became hyperglycemic up to 1 year of age. Our data suggest that activated B cells can down-regulate pathogenic Th1 immunity through triggering the apoptosis of Th1 cells and/or inhibition of APC activity by the secretion of TGF-beta. These findings provide new insights into T-B cell interactions and may aid in the design of new therapies for human T1DM. 相似文献
7.
8.
Nyland Cecilia Askham Modahl Ingunn Saur Raadal Hanne Lerche Hanssen Ole Jørgen 《The International Journal of Life Cycle Assessment》2003,8(6):331-336
Aim, Scope and Background When materials are recycled they are made available for use for several future life cycles and can therefore replace virgin
material more than just once. In order to analyse the optimal waste management system for a given material, the authors have
analysed the material flows in a life cycle perspective. It is important to distinguish this approach for material flow analysis
for a given material from life cycle analysis of products. A product life cycle analysis analyses the product system from
cradle to grave, but uses some form of allocation in order to separate the life cycle of one product from another in cases
where component materials are recycled. This paper does not address allocation of burdens between different product systems,
but rather focuses on methodology for decision making for waste management systems where the optimal waste management system
for a given material is analysed. The focus here is the flow of the given material from cradle (raw material extraction) to
grave (the material, or its inherent energy, is no longer available for use). The limitation on the number of times materials
can be recycled is set by either the recycling rate, or the technical properties of the recycled material.
Main Features This article describes a mathematical geometric progression approach that can be used to expand the system boundaries and
allow for recycling a given number of times. Case studies for polyethylene and paperboard are used to illustrate the importance
of including these aspects when part of the Goal and Scope for the LCA study is to identify which waste management treatment
options are best for a given material. The results and discussion examine the different conclusions that can be reached about
which waste management option is most environmentally beneficial when the higher burdens and benefits of recycling several
times are taken into account.
Results In order to assess the complete picture of the burdens and benefits arising from recycling the system boundaries must be expanded
to allow for recycling many times. A mathematical geometric progression approach manages to take into account the higher burdens
and benefits arising from recycling several times. If one compares different waste management systems, e.g. energy recovery
with recycling, without expanding the system to include the complete effects of material recycling one can reach a different
conclusion about which waste management option is preferred.
Conclusions When the purpose of the study is to compare different waste management options, it is important that the system boundaries
are expanded in order to include several recycling loops where this is a physical reality. The equations given in this article
can be used to include these recycling loops. The error introduced by not expanding the system boundaries can be significant.
This error can be large enough to change the conclusions of a comparative study, such that material recycling followed by
incineration is a much better option than waste incineration directly.
Recommendations and Outlook When comparing waste management solutions, where material recycling is a feasible option, it is important to include the relevant
number of recycling loops to ensure that the benefits of material recycling are not underestimated. The methodology presented
in this article should be used in future comparative studies for strategic decision-making for waste management. The approach
should not be used for LCAs for product systems without due care, as this could lead to double counting of the benefits of
recycling (depending on the goal and scope of the analysis). For materials where the material cycle is more of a closed loop
and one cannot truly say that recycled materials replace virgin materials, a more sophisticated approach will be required,
taking into account the fact that recycled materials will only replace a certain proportion of virgin materials. 相似文献
9.
M Alonso N Alonso Rodriguez C Garzelli M Martínez Lirola M Herranz S Samper MJ Ruiz Serrano E Bouza D García de Viedma 《BMC microbiology》2010,10(1):151
Background
The Beijing lineage of Mycobacterium tuberculosis is causing concern due to its global distribution and its involvement in severe outbreaks. Studies focused on this lineage are mainly restricted to geographical settings where its prevalence is high, whereas those in other areas are scarce. In this study, we analyze Beijing isolates in the Mediterranean area, where this lineage is not prevalent and is mainly associated with immigrant cases. 相似文献10.
Wood pellets,what else? Greenhouse gas parity times of European electricity from wood pellets produced in the south‐eastern United States using different softwood feedstocks 下载免费PDF全文
Steef V. Hanssen Anna S. Duden Martin Junginger Virginia H. Dale Floor van der Hilst 《Global Change Biology Bioenergy》2017,9(9):1406-1422
Several EU countries import wood pellets from the south‐eastern United States. The imported wood pellets are (co‐)fired in power plants with the aim of reducing overall greenhouse gas (GHG) emissions from electricity and meeting EU renewable energy targets. To assess whether GHG emissions are reduced and on what timescale, we construct the GHG balance of wood‐pellet electricity. This GHG balance consists of supply chain and combustion GHG emissions, carbon sequestration during biomass growth and avoided GHG emissions through replacing fossil electricity. We investigate wood pellets from four softwood feedstock types: small roundwood, commercial thinnings, harvest residues and mill residues. Per feedstock, the GHG balance of wood‐pellet electricity is compared against those of alternative scenarios. Alternative scenarios are combinations of alternative fates of the feedstock materials, such as in‐forest decomposition, or the production of paper or wood panels like oriented strand board (OSB). Alternative scenario composition depends on feedstock type and local demand for this feedstock. Results indicate that the GHG balance of wood‐pellet electricity equals that of alternative scenarios within 0–21 years (the GHG parity time), after which wood‐pellet electricity has sustained climate benefits. Parity times increase by a maximum of 12 years when varying key variables (emissions associated with paper and panels, soil carbon increase via feedstock decomposition, wood‐pellet electricity supply chain emissions) within maximum plausible ranges. Using commercial thinnings, harvest residues or mill residues as feedstock leads to the shortest GHG parity times (0–6 years) and fastest GHG benefits from wood‐pellet electricity. We find shorter GHG parity times than previous studies, for we use a novel approach that differentiates feedstocks and considers alternative scenarios based on (combinations of) alternative feedstock fates, rather than on alternative land uses. This novel approach is relevant for bioenergy derived from low‐value feedstocks. 相似文献