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81.
Junghans U Langenfeld-Heyser R Polle A Teichmann T 《Plant biology (Stuttgart, Germany)》2004,6(1):22-29
The influence of the auxin transport inhibitors naphthylphthalamic acid (NPA) and methyl-2-chloro-9-hydroxyflurene-9-carboxylate (CF), as well as the gaseous hormone ethylene on cambial differentiation of poplar was determined. NPA treatment induced clustering of vessels and increased vessel length. CF caused a synchronized differentiation of cambial cells into either vessel elements or fibres. The vessels in CF-treated wood were significantly smaller and fibre area was increased compared with controls. Under the influence of ethylene, the cambium produced more parenchyma, shorter fibres and shorter vessels than in controls. Since poplar is the model tree for molecular biology of wood formation, the modulation of the cambial differentiation of poplar towards specific cell types opens an avenue to study genes important for the development of vessels or fibres. 相似文献
82.
Giorcelli A Sparvoli F Mattivi F Tava A Balestrazzi A Vrhovsek U Calligari P Bollini R Confalonieri M 《Transgenic research》2004,13(3):203-214
When present, stilbene synthase leads to the production of resveratrol compounds, which are major components of the phytoalexin response against fungal pathogens of the plant and are highly bioactive substances of pharmaceutical interest. White poplar (Populus alba L.) was transformed with a construct containing a cDNA insert encoding stilbene synthase from grapevine (Vitis vinifera L.), under the control of the cauliflower mosaic virus (CaMV) 35S promoter, and a chimeric kanamycin resistance gene. Southern blot hybridization analysis demonstrated the presence and integration of exogenous DNA sequences in the poplar genome. Expression of the stilbene synthase-encoding gene in different transgenic lines was confirmed by Western blot and Northern analyses. Compared to the controls, in the transgenic plants two new compounds were detected and were identified as the trans- and cis-isomers of resveratrol-3-glucoside (piceid) by high-pressure liquid chromatography (HPLC), UV spectrophotometry, electrospray mass spectrometry (HPLC-ESI-MS) and enzymatic hydrolysis. Since poplar is a good biomass producer and piceids are accumulated in substantial amounts (up to 615.2 microg/g leaf fresh weight), the transgenic plants represent a potential alternative source for the production of these compounds with high pharmacological value. Despite the presence of piceid, in our experimental conditions no increased resistance against the pathogen Melampsora pulcherrima, which causes rust disease, was observed when in vitro bioassays were performed. 相似文献
83.
F.?Zhang Y.?L.?Yang W.?L.?He X.?Zhao L.?X.?ZhangEmail author 《In vitro cellular & developmental biology. Plant》2004,40(5):491-494
Summary The present study aimed to evaluate the response to salinity of Populus euphratica, which is more salt-resistant than other poplar cultivars, at the cellular level. To this purpose, callus was induced from
shoot segments of P. euphratica on Murashige and Skoog (MS) medium supplemented with 0.5 mg l−1 (2.2 μM) 6-benzyladenine (BA) and 0.5 mg l−1 (2.7 μM 1-naphthaleneacetic acid (NAA). Callus was transferred to MS medium supplemented with 0.25 mg l−1 (1.1 μM) BA and 0.5 mg l−1 NAA. The relative growth rate of callus reached a maximum in the presence of 50 mmol l−1 NaCl and growth was inhibited with increasing NaCl concentrations. Examination of the changes of osmotic substances under
salt stress showed that accumulation of proline, glycine betaine, and total soluble sugars increased with increasing salt
concentrations. The results indicate that the response of the callus of P. euphratica to salt stress is similar to that of the whole plant. 相似文献
84.
本文首次报道了杨白织潜蛾LeucopterasusinellaHerrich-Schaffer在贵州的发生危害情况,详细记述了杨白纹潜蛾各虫态的形态特征和生物学特性。在贵阳和铜仁地区,杨树受害株率达95%~100%,受害叶率达75%以上,受害叶每叶虫数3.6米以上,株虫口密度84.8头以上。该虫在铜仁地区1年发生5代,越冬代9月上旬化蛹,翌年4月上旬羽化。成虫寿命4~8天。卵块产于叶片正面贴近主脉或主侧脉处,卵历期2~5天,每卵块平均16卵粒。幼虫孵化时从卵壳底部咬孔潜入叶片组织取食叶肉,历期8~20天,幼虫老熟后咬破上表皮钻出,在被害叶片背面或吐丝下垂至下部叶片的叶背或下部主干与分技交界处的树皮裂缝中织“H”形茧化蛹。第一至第四代蛹历期为8~11天。本文还提出了该虫的防治方法。 相似文献
85.
This study was aimed at making a quantitative evaluation of the biomass, carbohydrates and mineral nutrients partitioning
in the canopy of aspen (Populus tremula L.) growing in a forest stand. Tree canopy biomass was divided into ten equal horizontal layers and the material for the
study was sampled from all canopy layers. The results indicated that the specific leaf mass and the dry matter content increased
but the area of leaves decreased toward the top of the canopy. The content of the non-structural carbohydrates depended largely
on the position of the leaves in the canopy and the N, P and K contents in the leaves, reaching a maximum in the upper canopy
layers better exposed to light. Regression analysis showed a linear relationship between the leaf mass per area and the percentage
of dry matter on the one hand and the content of carbohydrates, N, P and K in the canopy on the other.
Received: 11 March 1997 / Accepted: 16 June 1997 相似文献
86.
Jennifer Willms S. B. Rood Walter Willms Melvin Tyree 《Trees - Structure and Function》1998,12(4):215-223
The conservation of riparian (river valley flood plain) forests relies on the provision of instream flows that are sufficient
to sustain tree growth. In the present study, annual branch growth increments were investigated as an indicator of environmental
favorability for riparian cottonwoods. Trees of three species, Populus angustifolia, P. balsamifera, and P. deltoides, and their natural interspecific hybrids, were studied at five sites along the Oldman and South Saskatchewan rivers in Alberta,
Canada. Annual branch growth increments for the interval from 1983 to 1992 were positively correlated with stream flows (r
2 = 0.79 at Lethbridge) and slightly negatively correlated with weather variables that contribute to water demand: evaporation,
temperature, wind, and/or sunshine. The combination of January to May stream flow (water supply) and June evaporation (water
demand) almost entirely accounted for the branch growth variation across years (r
2 = 0.91 at Lethbridge). Tree ring increments were also investigated but were less closely correlated than branch increments
across trees or with stream flow. Branch growth increments thus provide an accurate but short duration (1 or 2 decades) record
of environmental favorability for growth. The close correlation between branch growth and stream flow indicates that water
is the principal limitation to growth of these riparian cottonwoods and that these trees obtained their water from a source
linked to the stream, the riparian water table. Analyses of branch increments should provide a management tool for (i) determining
instream flow needs for riparian cottonwoods and (ii) analyzing impacts of stream flow alterations due to river damming or
water diversion.
Received: 8 May 1997 / Accepted: 23 September 1997 相似文献
87.
Factors determining the midday depression of photosynthesis in trees under monsoon climate 总被引:9,自引:0,他引:9
Field studies of gas exchange of Populus deltoides, Prosopis juliflora and Acacia auriculiformis showed large diurnal changes in net photosynthesis (A) and stomatal conductance (gs) during autumn. P. deltoides and P. juliflora undergo pronounced midday depression in A and gs while A. auriculiformis showed a one-peak response. Several factors indicative of photosynthetic performance were found to be reversibly affected
during afternoon decline. These include (i) decrease in initial slope of the CO2 response curve (carboxylation efficiency), (ii) substantial increase in CO2 compensation point and (iii) decrease in overall quantum yield of photosystem II. The phenomenon can be duplicated in potted
plants by simulating a typical daily pattern of PPFD and VPD. It is found that high VPD induces significant decline in A and
gs at moderate temperature and saturating PPFD (800 μmol m–2 s–1) whereas these parameters are only marginally affected at high PPFD and low VPD. Fluorescence data show that the tree species
under study have a high capacity for safe dissipation of excessive excitation energy. The activation of photorespiration,
as evident from an increase in CO2 compensation point, maintains constant internal CO2 concentration (Ci) which may aid in minimizing photoinhibition during stomatal closure at midday. In case of P. deltoides and P. juliflora the stomata seem to be quite sensitive to the changes in humidity whereas this does not appear to be essential in case of
A. auriculiformis because of its phyllode structure that endows it with mechanisms for conserving water without undergoing large-scale stomatal
changes.
Received: 16 October 1997 / Accepted: 5 March 1998 相似文献
88.
The genetic structure of remaining black poplar ( Populus nigra ) trees on the banks of the Dutch Rhine branches was investigated using the AFLP technique. In total, 143 trees, including one P. deltoides and some P. x euramericana , were analysed using six AFLP primer combinations which generated 319 polymorphic bands. The AFLP patterns showed that some of the trees sampled as P. nigra were clearly different. These deviating patterns were also observed for the P. deltoides tree and all trees already identified as hybrid P. x euramericana . Hybrids between the two species are morphologically sometimes difficult to distinguish from the species itself. Two important possible source populations for recolonization of the riverbanks of the river Rhine, consisting of mature flowering P. nigra trees, appeared to consist of only a few genotypes each. In contrast, young black poplar trees growing alone or in small groups downstream of the possible source populations appeared to be predominantly generatively derived because no clones of mature trees were found among them. Therefore vegetative propagation seems a very local strategy whereas colonization of new areas appears to occur through generative propagation. Whether the genetic diversity within these black poplars is sufficient for recolonization of river banks and survival of the metapopulation is a question for further research. 相似文献
89.
Effects of overstory and understory vegetation on the understory light environment in mixed boreal forests 总被引:2,自引:0,他引:2
Abstract. The percentage of above-canopy Photosynthetic Photon Flux Density (%PPFD) was measured at 0, 50 and 100 cm above the forest floor and above the main understory vegetation in stands of (1) pure Betula papyrifera (White birch), (2) pure Populus tremuloides (Trembling aspen), (3) mixed broad-leaf-conifer, (4) shade-tolerant conifer and (5) pure Pinus banksiana (Jack pine) occurring on both clay and till soil types. %PPFD was measured instantaneously under overcast sky conditions (nine locations within each of 29 stands) and continuously for a full day under clear sky conditions (five locations within each of eight stands). The percentage cover of the understory layer was estimated at the same locations as light measurements. Mean %PPFD varied from 2% at the forest floor under Populus forests to 15% above the understory vegetation cover under Betula forests. Percent PPFD above the understory vegetation cover was significantly higher under shade intolerant tree species such as Populus, Betula and Pinus than under shade tolerant conifers. No significant differences were found in %PPFD above the understory vegetation cover under similar tree species between clay and till soil types. The coefficient of variation in %PPFD measured in the nine locations within each stand was significantly lower under deciduous dominated forests (mean of 19%) than under coniferous dominated forests (mean of 40%). %PPFD measured at the forest floor was positively correlated with %PPFD measured above the understory vegetation and negatively correlated with cumulative total percent cover of the understory vegetation (R2 = 0.852). The proportion of sunflecks above 250 and 500 mmol m–2 s–1 was much lower and %PPFD in shade much higher under Populus and Betula forests than under the other forests. Differences in the mean, variability and nature of the light environment found among forest and soil types are discussed in relation to their possible influences on tree succession. 相似文献
90.