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141.
Eberhard Gischler 《Facies》2010,56(2):173-177
Shallow fore-reef areas worldwide are usually characterized by spurs and grooves. A comparison of examples from the three
world oceans suggests that Indo-Pacific spurs and grooves are shaped predominantly by erosion, whereas western Atlantic spur
and groove systems are largely a product of constructive processes. I propose that this difference is caused by regional differences
in Holocene sea-level change, which controlled exposure to waves and currents, and reef-accretion rates. The transgressive–regressive
sea-level curve in the Indo-Pacific realm, i.e., the Mid-to-Late Holocene sea-level fall in these areas has maintained high-energy
conditions in the shallow fore reef. Higher exposure to waves and currents favors erosion and leads to a dominance of crustose
coralline algae that have relatively slow growth rates. In the western Atlantic, the transgressive Holocene sea level has
caused Mid-to-Late Holocene deepening and has maintained accommodation space for reef accretion. Fast-growing acroporid corals
thrive under lower exposure and are more common than coralline algae. The fossil record of the spur and groove system is rather
poor, which is probably a consequence of the need of excellent, three-dimensional outcrops for identification. 相似文献
142.
143.
144.
Steven I. Higgins Robert B. O’Hara Olga Bykova Michael D. Cramer Isabelle Chuine Eva‐Maria Gerstner Thomas Hickler Xavier Morin Michael R. Kearney Guy F. Midgley Simon Scheiter 《Journal of Biogeography》2012,39(12):2132-2145
Aim To develop a physiologically based model of the plant niche for use in species distribution modelling. Location Europe. Methods We link the Thornley transport resistance (TTR) model with functions which describe how the TTR’s model parameters are influenced by abiotic environmental factors. The TTR model considers how carbon and nutrient uptake, and the allocation of these assimilates, influence growth. We use indirect statistical methods to estimate the model parameters from a high resolution data set on tree distribution for 22 European tree species. Results We infer, from distribution data and abiotic forcing data, the physiological niche dimensions of 22 European tree species. We found that the model fits were reasonable (AUC: 0.79–0.964). The projected distributions were characterized by a false positive rate of 0.19 and a false negative rate 0.12. The fitted models are used to generate projections of the environmental factors that limit the range boundaries of the study species. Main conclusions We show that physiological models can be used to derive physiological niche dimensions from species distribution data. Future work should focus on including prior information on physiological rates into the parameter estimation process. Application of the TTR model to species distribution modelling suggests new avenues for establishing explicit links between distribution and physiology, and for generating hypotheses about how ecophysiological processes influence the distribution of plants. 相似文献
145.
The climbing habit has evolved independently in many plant taxa, offering vines the ability to compete with non-climbing vegetation
for resources such as light, nutrients, and water. This review examines the structural and functional characteristics that
allow climbing plants to (1) achieve widespread dispersal, (2) transport large amounts of water throughout vessels, (3) maintain
high photosynthesis levels through a large leaf area to biomass ratio, (4) achieve rapid vertical and horizontal expansion
by fast growth rates and various climbing mechanisms and (5) survive and recover from disturbances. Due to the competitive
effects of vines on trees, management of vine growth is used to preserve tropical timber plantations, combat invasive weeds,
and promote rainforest recovery. In order to sustainably manage the vines into the future, it is necessary to understand the
mechanisms by which they can alter tropical forest succession and the impacts of various management techniques. 相似文献
146.
147.
Previous studies by us and others established that cell-cell adhesion is mediated by specific carbohydrate-to-carbohydrate
interaction (CCI). Those previous studies were based on various biochemical and biophysical approaches, including the use
of labeled glycosyl epitopes with fluorescent tag. However, these methods ideally require that the glycosyl epitope must be
fixed to a solid phase molecule, preferably with multivalency. The purpose of the present study is to establish a CCI process
using specific glycosyl residues conjugated to biotinylated diaminopyridine (BAP), and to observe: (i) clear occurrence of
homotypic CCI between “Os Fr.B” having 5–6 GlcNAc termini, vs. absence of such homotypic CCI between “Os Fr.1” having 2 GlcNAc termini; (ii) occurrence of heterotypic CCI between GM3
ganglioside and Os Fr.B, vs. absence of such heterotypic CCI between GM3 and Os Fr.1. Interaction between Os Fr.B-BAP conjugate and Os Fr.B-ceramide
mimetic (Os Fr.B-mCer) was demonstrated based on two experiments: (i) dose-dependent binding of Os Fr.B-BAP conjugate to polystyrene
plates coated with Os Fr.B-mCer was observed in the presence of bivalent cation, a prerequisite for all CCI processes, and
such binding was abolished by EDTA; (ii) binding between equal nanomolar Os Fr.B-BAP and Os Fr.B-mCer was inhibited by mM
concentration Os Fr.B without conjugate, in dose-dependent manner. Thus, cell adhesion processes based on homotypic CCI between
N-linked glycans having multiple GlcNAc termini, and heterotypic CCI between GM3 and such glycans, were clearly observed using
BAP conjugates of glycosyl epitopes. 相似文献
148.
Background
Many molecules are flexible and undergo significant shape deformation as part of their function, and yet most existing molecular shape comparison (MSC) methods treat them as rigid bodies, which may lead to incorrect shape recognition. 相似文献149.
Gillian D Alton David L Pearl Ken G Bateman W Bruce McNab Olaf Berke 《BMC veterinary research》2010,6(1):42
Background
Ontario provincial abattoirs have the potential to be important sources of syndromic surveillance data for emerging diseases of concern to animal health, public health and food safety. The objectives of this study were to: (1) describe provincially inspected abattoirs processing cattle in Ontario in terms of the number of abattoirs, the number of weeks abattoirs process cattle, geographical distribution, types of whole carcass condemnations reported, and the distance animals are shipped for slaughter; and (2) identify various seasonal, secular, disease and non-disease factors that might bias the results of quantitative methods, such as cluster detection methods, used for food animal syndromic surveillance. 相似文献150.
Knowledge on transport and deposition of fine particulate organic matter (FPOM) from reservoir dams is increasingly required
for habitat management and restoration of dam tailwater ecosystems. Variations in the transport distance of FPOM, however,
have never been studied well, particularly in relation to channel morphology, due to channel size restrictions of artificial
tracers such as corn pollen when applied to larger river channels. This study aims to show the relations between FPOM retention
efficiency and channel morphology in dam tailwaters using lentic plankters as tracers. We estimated the mean transport distance,
S
p, by calculating downstream reduction ratios of lentic tracer plankters and calculated the deposition velocity, v
dep. Suspended FPOM samples were collected in tailwaters of two river channels below reservoir dams and two artificial canals
below Lake Biwa in the Yodo River system. The longest S
p (19.2 km) and the shortest one (2.2 km) were recorded in the deep canal and shallow canal, respectively, showing a positive
correlation with channel hydraulic radius. The values of v
dep were 4.7–6.4 times higher in river channels than in artificial canals. These results indicate that increasing complexity
of bed morphology can minimize S
p, whereas bed degradation and armored bed materials may lead to increased S
p. Advantages of lentic plankters as tracers for estimating distance ranges of reservoir dam impact on river ecosystems are
also discussed. 相似文献