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991.
Thomas Ledermann 《European Journal of Forest Research》2011,130(4):521-531
In this study, a non-linear model was developed that predicts the five-year change of height to crown base (HCB) of Norway
spruce (Picea abies [L.] Karst.). Data were available from the Austrian National Forest Inventory and comprised 2,419 trees from 1,637 permanent
sample plots measured during 1981 and 2002. The dynamic model explained 36% of the variation in the observed change of HCB.
It is well behaved and meets biological expectations. Based on five independent data sets, the predictive ability of the new
dynamic model was compared to an already existing static crown ratio model. For this comparison, the models were applied as
follows: the new ∆ HCB model was used to predict the change in HCB directly. For the semi-dynamic method, the static model
was applied at the end and at the start of the growth period to obtain two estimates of HCB. The difference of these two estimates
was then added to the initial HCB. For the static method, the model was only applied at the end of the prediction period to
obtain the new estimate of HCB. Except for one plot, the new ∆ HCB model yielded the smallest BIAS and the highest precision,
followed by the semi-dynamic and the static method. Because the independent data sets cover a broad range of age classes and
thinning regimes, the validation results also indicate that the new ∆ HCB is robust and the effect of stand management is
adequately represented. 相似文献
992.
Natalia Kirichenko Julie Flament Yuri Baranchikov Jean-Claude Grégoire 《European Journal of Forest Research》2011,130(6):1067-1074
The Siberian moth, Dendrolimus sibiricus, Tschtv. is the most harmful defoliator of coniferous forests in North Asia. The pest has already spread over the Urals and
continues moving westwards. Recently, it has been recommended for quarantine in member countries by European and Mediterranean
Plant Protection Organization (EPPO). The performances of the pest on coniferous species planted in Europe were assessed on
a range of potted trees corresponding to the spectrum of economically important conifers in the EU: European larch Larix decidua, Norway spruce Picea abies, Scots pine Pinus sylvestris, European black pine Pinus nigra, and the North American species: Douglas fir Pseudotsuga menziesii and grand fir Abies grandis. Larvae showed a potential to survive and complete the development on all these host tree species. Favorable hosts were grand
fir, European larch, and Douglas fir that allowed higher survival, better larval development, and as a result, yielded heavier
pupae and adult moths with higher longevity. Black pine was a poor host but, however, could still support larval and pupal
development. Norway spruce and Scots pine had an intermediate behavior. If accidentally introduced to Europe, the Siberian
moth may become especially damaging in forest stands predominated by European larch and by the North American firs. Norway
spruce and especially the two-needle pines will be less prone to intensive defoliation by this species. The fact that the
pest may damage the range of economically important coniferous species should be taken into account in the pest risk assessment
for Europe and also for North America where the Siberian moth occurrence is considered likely. 相似文献
993.
Raffaele Spinelli Natascia Magagnotti Carla Nati 《European Journal of Forest Research》2011,130(5):737-744
In Italy, poplar plantations represent an important source of wood products, and especially of high-quality veneer logs. These
plantations offer favourable conditions to the introduction of forest mechanisation, and especially easy access and industrial
management. However, owners fear that mechanised log-making may cause value losses, due to poor length measurement, log surface
damage and improper grading. This study compared the performance of manual and mechanised log-making on ten commercial operations,
in order to determine the occurrence and the severity of possible value losses due to product degrade. The study found that
length measurement errors are smaller for mechanised processing, while the frequency and severity of log surface damage are
the same for both treatments. In three cases out of five, mechanised log-making extracted the same value from the stems as
manual log-making: in the remaining two, differences were very small and went opposite directions. Significant differences
were found between operators, stressing the importance of operator skills and motivation. In fact, the log-making specifications
and the pricing structure applied to poplar processing are relatively simple and are unlikely to challenge the ability of
personnel and equipment. At present, most Italian poplar growers are unaware of the potential offered by modern technology,
whose intelligent use would boost value recovery and decrease harvesting cost. Significant benefits may derive from the introduction
of optimised bucking, which may help shifting to a more articulated and rewarding product strategy. 相似文献
994.
Stefano Casalegno Giuseppe Amatulli Annemarie Bastrup-Birk Tracy Houston Durrant Anssi Pekkarinen 《European Journal of Forest Research》2011,130(6):971-981
Proactive forest conservation planning requires spatially accurate information about the potential distribution of tree species.
The most cost-efficient way to obtain this information is habitat suitability modelling i.e. predicting the potential distribution
of biota as a function of environmental factors. Here, we used the bootstrap-aggregating machine-learning ensemble classifier
Random Forest (RF) to derive a 1-km resolution European forest formation suitability map. The statistical model use as inputs
more than 6,000 field data forest inventory plots and a large set of environmental variables. The field data plots were classified
into different forest formations using the forest category classification scheme of the European Environmental Agency. The
ten most dominant forest categories excluding plantations were chosen for the analysis. Model results have an overall accuracy
of 76%. Between categories scores were unbalanced and Mesophitic deciduous forests were found to be the least correctly classified
forest category. The model’s variable ranking scores are used to discuss relationship between forest category/environmental
factors and to gain insight into the model’s limits and strengths for map applicability. The European forest suitability map
is now available for further applications in forest conservation and climate change issues. 相似文献
995.
Rohny Setiawan Maail Kenji Umemura Hideo Aizawa Shuichi Kawai 《Journal of Wood Science》2011,57(4):302-307
This study examined the effects of supercritical CO2 treatment on the curing and degradation of cementbonded particleboard (CBP). Significant correlations were found between
the supercritical CO2 treatment and mechanical properties during both curing and degradation processes. Internal bond (IB) strength, modulus of
rupture (MOR), and modulus of elasticity (MOE) values of CBP achieved their maximums by supercritical CO2 treatment in 30 min. These conditions indicated that supercritical CO2 treatment accelerates the curing process rapidly and enhances the mechanical properties of the CBP. However, these values
decreased in treatment from 60 min to 10 days and had a negative effect on board performance, indicating that supercritical
CO2 treatment over a longer time span leads to degradation of the CBP. Furthermore, X-ray diffractometry (XRD), thermal gravimetry
(TG-DTG), and scanning electron microscopy (SEM) observation clarified that the mechanisms of degradation are directly affected
by the mineralogical composition of the system, in par ticular, by the calcium carbonate content as caused by carbonation. 相似文献
996.
997.
998.
Mikko Mönkkönen Pasi Reunanen Janne S. Kotiaho Artti Juutinen Olli-Pekka Tikkanen Jari Kouki 《European Journal of Forest Research》2011,130(5):717-727
Setting aside parcels of land is the main conservation strategy to reduce the rate of biodiversity loss worldwide. Because
funding for biological conservation is limited, it is important to distinguish the most efficient ways to use it. Here, we
assess implications of alternative measures to conserve biodiversity in managed boreal forest landscapes. We calculated four
alternative spatio-temporal scenarios and compared these to the current management regime over 100-year time period. In the
alternative scenarios, a fixed amount of funding was invested in (1) permanent large reserves (each tens of ha in size), (2)
permanent small reserves (each a few ha in size), (3) temporary small reserves (based on 10-year contracts with private land
owners), and (4) green-tree retention (small groups of trees retained on clear-cuts). To assess biodiversity implications,
we used habitat suitability indices to calculate overall habitat availability for five groups of red-listed and habitat-specific
species associated with decaying spruce logs. The possibilities for timber harvests did not differ among the scenarios, but
biodiversity performance was different. The scenarios with permanent reserves tended to outperform other scenarios, suggesting
that conservation policies based on permanent reserves are the most cost-efficient in the long term. Results, however, varied
among time scales and species groups. In the short term, a strategy of investment in temporary small reserves was the most
efficient. Habitat for species associated with old spruce dead-wood and preferring shade was rare throughout all simulations,
and therefore, it is likely that these species cannot be sustained in managed forests. Species that live on fresh dead-wood
and are associated with forest edges coped well in all scenarios suggesting that such species will persist in managed landscapes
without additional conservation efforts. Explicit definition of conservation objectives and time frames for conservation action
are thus prerequisites for successful conservation planning. 相似文献
999.
1000.