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991.
The incertae sedis Carpathoporella Dragastan, 1995, reported from the Lower Cretaceous of the Western Tethyan domain, is usually interpreted as remains of calcareous algae
(Dasycladales or Characeae). New thin-section material from the Aptian of Albania sheds light not only on its biogenic nature
but also on the morphological variability of this taxon. In fact, Carpathoporella represents the debris of colonial, bushy, most likely gorgonid octocorals with tuberculated spheroids that may be fused at
least near the basal root-like holdfast. Colony branching originates from longitudinally grooved calcareous branches or internodes.
Possible relationships to other Upper Cretaceous to Palaeogene genera are discussed and a revised critical inventory of Cretaceous
octocorals is presented. Due to the evidenced morphological features, Carpathoporella could either represent an ancestral isidid octocoral of the order Alcyonacea such as Moltkia Steenstrup or, due to the likely primary aragonitic skeletal mineralogy, a representative of Epiphaxum Lonsdale of the order Helioporacea. Due to morphological analogies, the new combination Carpathoporella elliotti (Radoičić) is proposed. In any case, the Lower Cretaceous record from Tethyan peri-reefal shallow-water carbonates is highlighted
since numerous skeletal findings of fossil gorgonid Octocorallia were so far only known from Upper Cretaceous and younger
strata of outer shelf environments of the boreal realm. The origin of deep-water Upper Cretaceous octocorals from Lower Cretaceous
shallow-water taxa such as Carpathoporella is proposed as a possible further example of onshore/offshore evolutionary pattern. 相似文献
992.
Plasmonic nanorods and their clusters are the fundamental units in plasmonic nanoantenna engineering. A theory that can predict the resonance of single nanorod already exists but is in lack for a heterodimer. Here, we propose a model combining the effective circuit theory for the response of spherical nanoparticles together with standard transmission line theory for hemispherically capped nanorod antennas. The resonances of multiple orders are predictable by defining the reflection phase at the terminals of such antennas, in both symmetric and asymmetric coupled nanorods. The theoretical results compare favorably with full-wave finite element numerical calculations. By the analytical formula, it is easy to control the length of the antennas for regulating the cooperative resonant properties and consequently the radiation characteristics of a nearby electric dipole. Consequently, we obtain both commensurate and incommensurate resonance features in such nanorod-based heterodimer antennas, showing respectively cumulative and selective responses from the individual nanorods. 相似文献
993.
RICHARD M. WEINSHILBOUM RICHARD KVETNANSKY JULIUS AXELROD IRWIN J. KOPIN 《Nature: New biology》1971,230(17):287-288
THE formation of the neurotransmitter noradrenaline from 3,4-dihydroxyphenylethylamine (dopamine) is catalysed by the enzyme dopamine-β-hydroxylase (DBH)1. This enzyme is associated both with the catecholamine-containing chromaffin granules in the adrenal medulla2,3 and with the vesicular structures in sympathetic nerve terminals which contain catecholamines4. Furthermore, DBH activity is released with catecholamines into the perfusate after stimulation of either the isolated perfused adrenal gland5 or the isolated perfused spleen6–8. DBH activity has been reported in the serum of both man and the rat9,10. This activity is similar to adrenal and sympathetic nerve DBH activity with regard to cofactor requirements, oxygen requirement and kinetic characteristics9,10. It has been suggested that serum DBH activity might be present as a result of release of enzyme with catecholamines from the adrenal glands and sympathetic nerves. If this is the case, serum DBH activity might be a useful and convenient index of sympathetic-adrenal activity. The work described here was undertaken to investigate both the source of the serum DBH and the effect on this activity of forced immobilization, a procedure which has been used as a model of stress and which has been shown to release catecholamines from the adrenal gland and increase catecholamine excretion11. 相似文献
994.
Protein is one of the three main storage chemical components in maize grains, and is negatively correlated with starch concentration
(SC). Our objective was to analyse the influence of genetic backgrounds on QTL detection for protein concentration (PC) and
to reveal the molecular genetic associations between PC and both SC and grain weight (GWP). Two hundred and eighty-four (Pop1)
and 265 (Pop2) F2:3 families were developed from two crosses between one high-oil maize inbred GY220 and two normal maize inbreds 8984 and 8622
respectively, and were genotyped with 185 and 173 pairs of SSR markers. PC, SC and GWP were evaluated under two environments.
Composite interval mapping (CIM) and multiple interval mapping (MIM) methods were used to detect single-trait QTL for PC,
and multiple-trait QTL for PC with both SC and GWP. No common QTL were shared between the two populations for their four and
one PC QTL. Common QTL with opposite signs of effects for PC and SC/GWP were detected on three marker intervals at bins 6.07–6.08,
8.03 and 8.03–8.04. Multiple-traits QTL mapping showed that tightly-linked QTL, pleiotropic QTL and QTL having effects with
opposite directions for PC and SC/GWP were all observed in Pop1, while all QTL reflected opposite effects in Pop2. 相似文献
995.
996.
The climate (especially temperature) often plays an important role in the structure, function as well as composition of soil organisms in different latitudes and altitudes. As one of the essential components of soil ecosystem, soil faunal community not only lays their roles as soil engineer in material cycling and energy flow, but also acts as the sensitive bio-indicator to environmental change. However, little information has been available on the responses of soil faunal community to the changed environment at different altitudes and seasons. In order to understand the seasonal dynamics of soil faunal diversity under different forests with varying altitudes, three fir (Abies faxoniana) forests were selected covering a 600 m vertical transition zone. The primary fir forest at 3600 m (A1) of altitude, mixed fir and birch forest at 3300 m (A2) of altitude, and secondary fir forest at 3000 m (A3) of altitude are representative forests in the subalpine and alpine region of west Sichuan. A 2 years study was conducted in the three subalpine and alpine forests from May in 2009 until October in 2010. Soil samples were collected in both the soil organic layer and mineral soil layer. Soil macro-fauna were picked up by hand in the fields. Meso/micro-fauna and damp living fauna were separated and collected from the soil samples by Baermann and Tullgren methods in laboratory, respectively. A total of 74,827 individuals were collected in the 2 years, belonging to seven phyla, 16 classes, 31 orders and 125 families by preliminary identification. Similar dominant groups were detected in different forests at different altitudes, consisting of Spirostreptida, Formicidae, Staphylinidae, Hesperinidae, Onychiuridae, Isotomidae, Oribatuloidae, Alicoragiidae, Secernentea, and Adenophorea. In contrast, the ordinary species of macro-fauna and the ratios of Acarina to Collembolan were obviously different. For instance, the ordinary species were dominated by Cydmaenidae and Mycetophilidae at the A1, Scaphidiidae and Helicinidae at the A2, and Lumbricida and Agelenidae at the A3, respectively. Both the individual density and the number of soil faunal groups were significantly higher in soil organic layer than those in mineral soil layer. The density and group of macro-, meso- and micro-fauna in different forests showed the order as A2 > A1 > A3, but the density of damp living fauna showed the order as A1 > A2 > A3. The functional groups of macro-fauna were mainly dominated by saprozoic. The highest density and group of macro-fauna was observed in August, while the highest value of meso/micro-fauna was detected in October. In addition, the Jacard similarity indices showed that the composition and structure of soil fauna were similar in the different forests varied with altitudes, but the Shannon–Wiener indices were significantly different. The highest values of Shannon–Wiener indices were observed in October at both the A1 and A3, and in August at the A2. The results suggested that soil faunal community kept a high diversity in the subalpine and alpine forests of west Sichuan, and their structures were significantly affected by the variation of altitudes, which provided important scientific evidences for understanding the ecological processes in the subalpine and alpine coniferous forests. 相似文献
997.
Tai‐An Chiang Yu‐Lin Yang Ya‐Ying Yang Min‐Hsiu Hu Pei‐Fen Wu Shu‐Fen Liu Ruay‐Ming Huang Tung‐Nan Liao Chien‐Ya Hung Tsung‐Jen Hung Tao‐Chen Lee 《Journal of cellular biochemistry》2010,109(4):663-671
Hyperosmolarity plays an essential role in the pathogenesis of diabetic tubular fibrosis. However, the mechanism of the involvement of hyperosmolarity remains unclear. In this study, mannitol was used to evaluate the effects of hyperosmolarity on a renal distal tubule cell line (MDCK). We investigated transforming growth factor‐β receptors and their downstream fibrogenic signal proteins. We show that hyperosmolarity significantly enhances the susceptibility to exogenous transforming growth factor (TGF)‐β1, as mannitol (27.5 mM) significantly enhanced the TGF‐β1‐induced increase in fibronectin levels compared with control experiments (5.5 mM). Specifically, hyperosmolarity induced tyrosine phosphorylation on TGF‐β RII at 336 residues in a time (0–24 h) and dose (5.5–38.5 mM) dependent manner. In addition, hyperosmolarity increased the level of TGF‐β RI in a dose‐ and time‐course dependent manner. These observations may be closely related to decreased catabolism of TGF‐β RI. Hyperosmolarity significantly downregulated the expression of an inhibitory Smad (Smad7), decreased the level of Smurf 1, and reduced ubiquitination of TGF‐β RI. In addition, through the use of cycloheximide and the proteasome inhibitor MG132, we showed that hyperosmolarity significantly increased the half‐life and inhibited the protein level of TGF‐β RI by polyubiquitination and proteasomal degradation. Taken together, our data suggest that hyperosmolarity enhances cellular susceptibility to renal tubular fibrosis by activating the Smad7 pathway and increasing the stability of type I TGF‐β receptors by retarding proteasomal degradation of TGF‐β RI. This study clarifies the mechanism underlying hyperosmotic‐induced renal fibrosis in renal distal tubule cells. J. Cell. Biochem. 109: 663–671, 2010. © 2010 Wiley‐Liss, Inc. 相似文献
998.
James P. Kehrer 《Cell biology and toxicology》2010,26(2):83-89
Survival and apoptosis signaling pathways are altered concomitantly in response to numerous endogenous and exogenous stressors.
The lipocalin family of small soluble proteins has been implicated in modulating apoptosis. However, the overall effect of
these proteins has been variable, showing both pro- and anti-apoptotic activities. The goal of this minireview is to summarize
the studies on lipocalins and apoptosis and consider what roles lipocalin-2 may play in cell death and survival. 相似文献
999.
Angiogenesis is the formation of new blood vessels from pre-existing vasculature. Pathologic angiogenesis in the eye can lead
to severe visual impairment. In our review, we discuss the roles of both pro-angiogenic and anti-angiogenic molecular players
in corneal angiogenesis, proliferative diabetic retinopathy, exudative macular degeneration and retinopathy of prematurity,
highlighting novel targets that have emerged over the past decade. 相似文献
1000.
N. T. Moldogazieva K. V. Shaitan K. B. Tereshkina Yu. M. Antonov A. A. Terentiev 《Biophysics》2007,52(4):365-374
A comparative study of the conformation dynamics of the human alpha-fetoprotein fragment LDSYQCT and heptapeptides derived from it by point substitutions has revealed a significant influence of electrostatic interactions on the set of preferred conformations and dynamics of amino acid residues when the peptides with blocked termini are examined at ? = 1. Peptide flexibility rises when the termini are left free (charged). At ? = 10 or 80, the set of probable conformations for all residues expands to much the same extent, i.e., at higher permittivity of the medium the dynamic effects of amino acid changes are leveled off. 相似文献