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91.
Yahya Al-Abed Emma Gray Konrad Wolfe Gavin W Watters Jonathan M Philpott 《International Seminars in Surgical Oncology : ISSO》2008,5(1):14
Background
Hurthle cell carcinoma of the thyroid is a rare form of thyroid cancer. It may present as a low grade tumour or can present as a more aggressive metastatic carcinoma. Hurthle cell carcinoma has the highest incidence of metastasis among all differentiated thyroid cancers. Most commonly haematogenous spread to lungs, bones and brain, however spread to regional lymph nodes is not uncommon. The breast is a rare site for metastasis from extramammary sources. We present the first case of breast metastasis from Hurthle cell carcinoma of the thyroid.Case presentation
We report a 77 year old lady who had total thyroidectomy and bilateral neck dissection followed by radiotherapy for a high grade metastatic Hurthle cell carcinoma of the thyroid. Ten months later she presented to the breast clinic with left breast lump and a lump at the left axilla. Fine needle aspiration cytology of the lumps and histology after wide local excision of the breast lump confirmed metastatic Hurthle cell carcinoma.Conclusion
The presence of breast lumps in patients with history of extramammary cancer should raise the possibility of metastasis.92.
Monotosylation of 1,6-anhydro-β-D-glucofuranose is a highly selective process, which yields the 5-O-tosyl derivative 2 preferentially (77%). By-products of the reaction are the 2-O-monotosyl derivative (6%) and the 2,5- and 3,5-di-O-tosyl derivatives (both 5%). The substitution pattern of all compounds was derived from n.m.r. spectra, especially from those of the acetylated compounds. Attempts to use 2 in the synthesis of 1,6-anhydro-α-L-idofuranose by intermolecular nucleophilic substitution failed, but instead yielded 1,6:3,5-dianhydro-α-L-idofuranose. This first representative of a new class of dianhydrohexoses was characterized by n.m.r. and m.s. Acetylation gave the 2-monoacetate showing an n.m.r. spectrum in agreement with the proposed structure. This tricyclic structure is expected to be very rigid and is composed of four-, five-, six-, seven-, and eight-membered rings. 相似文献
93.
Bacterial light-harvesting II (LH-II) centers contain two types of Bacteriochlorophylls (Bchl). One is named B800 and found
as a single molecule within one monomer of the complex while the other named B850 is found as a dimer. Their names indicate
their peak of UV absorbance around red spectrum. Both types of molecules are attached to the protein chain via ligation of
their central Magnesium atom to an either Histidine or Deoxymethionine amino acid. They are also coordinated by peripheral
hydrogen bonds that they accept with their carboxyl side group. Both the ligation and the hydrogen bonding are thought to
have an effect on electronic structure of the Bchl hence its UV absorbance and energy transfer rate. Experiments and theoretic
studies performed on this subject support the above idea. This theoretical molecular modeling study case aims to mimic the
experimental mutations performed on certain amino acids in silico and study its effects on the electronic structure of Bchl. By comparison with experimental results it was observed that the
likely place for the nearby Arginine is not below the plane of the Bchl as in the X-ray crystallographic structure but above
the plane defined by the four nitrogen atoms and their rings. It was also seen that the coordination of the acetyl group is
very sensitive to changes in ligation of the Bchl molecule. 相似文献
94.
A key requirement for encoding the auditory environment is the ability to dynamically alter cochlear sensitivity. However,
merely attaining a steady state of maximal sensitivity is not a viable solution since the sensory cells and ganglion cells
of the cochlea are prone to damage following exposure to loud sound. Most often, such damage is via initial metabolic insult
that can lead to cellular death. Thus, establishing the highest sensitivity must be balanced with protection against cellular
metabolic damage that can lead to loss of hair cells and ganglion cells, resulting in loss of frequency representation. While
feedback mechanisms are known to exist in the cochlea that alter sensitivity, they respond only after stimulus encoding, allowing
potentially damaging sounds to impact the inner ear at times coincident with increased sensitivity. Thus, questions remain
concerning the endogenous signaling systems involved in dynamic modulation of cochlear sensitivity and protection against
metabolic stress. Understanding endogenous signaling systems involved in cochlear protection may lead to new strategies and
therapies for prevention of cochlear damage and consequent hearing loss. We have recently discovered a novel cochlear signaling
system that is molecularly equivalent to the classic hypothalamic–pituitary–adrenal (HPA) axis. This cochlear HPA-equivalent
system functions to balance auditory sensitivity and susceptibility to noise-induced hearing loss, and also protects against
cellular metabolic insults resulting from exposures to ototoxic drugs. We review the anatomy, physiology, and cellular signaling
of this system, and compare it to similar signaling in other organs/tissues of the body. 相似文献
95.
A wide diversity of models have been proposed to account for the spiking response of central neurons, from the integrate-and-fire
(IF) model and its quadratic and exponential variants, to multiple-variable models such as the Izhikevich (IZ) model and the
well-known Hodgkin–Huxley (HH) type models. Such models can capture different aspects of the spiking response of neurons,
but there is few objective comparison of their performance. In this article, we provide such a comparison in the context of
well-defined stimulation protocols, including, for each cell, DC stimulation, and a series of excitatory conductance injections,
arising in the presence of synaptic background activity. We use the dynamic-clamp technique to characterize the response of
regular-spiking neurons from guinea-pig visual cortex by computing families of post-stimulus time histograms (PSTH), for different
stimulus intensities, and for two different background activities (low- and high-conductance states). The data obtained are
then used to fit different classes of models such as the IF, IZ, or HH types, which are constrained by the whole data set.
This analysis shows that HH models are generally more accurate to fit the series of experimental PSTH, but their performance
is almost equaled by much simpler models, such as the exponential or pulse-based IF models. Similar conclusions were also
reached by performing partial fitting of the data, and examining the ability of different models to predict responses that
were not used for the fitting. Although such results must be qualified by using more sophisticated stimulation protocols,
they suggest that nonlinear IF models can capture surprisingly well the response of cortical regular-spiking neurons and appear
as useful candidates for network simulations with conductance-based synaptic interactions. 相似文献
96.
Increasing maize seed weight by enhancing the cytoplasmic ADP-glucose pyrophosphorylase activity in transgenic maize plants 总被引:2,自引:1,他引:2
Zhangying Wang Xiaoping Chen Jianhua Wang Tingsong Liu Yan Liu Li Zhao Guoying Wang 《Plant Cell, Tissue and Organ Culture》2007,88(1):83-92
ADP-glucose pyrophosphorylase (AGPase) plays a key role in regulating starch biosynthesis in cereal seeds and is likely the
most important determinant of seed strength. The Escherichia coli mutant glgC gene (glgC16), which encodes a highly active and allosterically insensitive AGPase, was introduced into maize (Zea mays L.) under the control of an endosperm-specific promoter. Developing seeds from transgenic maize plants showed up to 2–4-fold
higher levels of AGPase activity in the presence of 5 mM inorganic phosphate (Pi). Transgenic plants with higher cytoplasmic
AGPase activity under Pi-inhibitory conditions showed increases (13–25%) in seed weight over the untransformed control. In
addition, in all transgenic maize plants, the seeds were fully filled, and the seed number of transgenic plants had no significant
difference compared with that of untransformed control. These results indicate that increasing cytoplasmic AGPase activity
has a marked effect on sink activity and, in turn, seed weight in transgenic maize plants. 相似文献
97.
Two new cycloartane-type glycosides oleifoliosides A (1) and B (2) were isolated from the lower stem parts of Astragalus oleifolius. Their structures were identified as 3-O-[beta-xylopyranosyl-(1 --> 2)-alpha-arabinopyranosyl]-6-O-beta-xylopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane and 3-O-[beta-xylopyranosyl-(1 --> 2)-alpha-arabinopyranosyl]-6-O-beta-glucopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane, respectively, by means of spectroscopic methods (IR, 1D and 2D NMR, ESI-MS). Three known cycloartane glycosides cyclocanthoside E (3), astragaloside II (4) and astragaloside IV (5) were also isolated and characterized. All five compounds were evaluated for in vitro trypanocidal, leishmanicidal and antiplasmodial activities as well as their cytotoxic potential on primary mammalian (L6) cells. Except for the compound 5, all compounds showed notable growth inhibitory activity against Leishmania donovani with IC50 values ranging from 13.2 to 21.3 microg/ml. Only weak activity against Trypanosoma brucei rhodesiense was observed with the known compounds astragaloside II (4, IC50 66.6 microg/ml) and cyclocanthoside E (3, IC50 85.2 microg/ml), while all compounds were inactive against Trypanosoma cruzi and Plasmodium falciparum. None of the compounds were toxic to mammalian cells (IC50's > 90 microg/ml). This is the first report of leishmanicidal and trypanocidal activity of cycloartane-type triterpene glycosides. 相似文献
98.
The present work proposes new boundaries for the current submediterranean territories of the Iberian Peninsula, defining them
at the smallest scale attempted to date. The boundaries proposed are not sharp divisions but somewhat ‘gradual’, reflecting
the transitional nature of the territories they encompass. Climate change predictions were used to estimate how the distribution
of these submediterranean regions might change in the near future. The maps constructed are based on the distribution of marcescent
Quercus species—trees that characterise the submediterranean plant landscape where they form the main forest communities. To determine
their climatic range, the distribution of different types of Iberian oak forest was represented in ‘climate diagrams’ (ordination
diagrams derived from principal components analysis), both in terms of individual species and groups of species based on leaf
ecophysiological type, i.e. marcescent (Submediterranean), sclerophyllous (Mediterranean), semideciduous (Mediterranean) and
deciduous (Eurosiberian). The climate range of each type of forest was determined, and the means of representative climate
variables are analysed by one way ANOVA. The variables differentiating the forest groups were also examined by discriminant
analysis. The range of the climate variables found to be associated with the majority of marcescent forests was used to determine
the distribution of territories throughout the Peninsula with the same conditions (i.e. whether marcescent forests were present
or not), thus providing a map of the Iberian submediterranean territories. Predictions of climate change were used to investigate
possible climate-induced modifications in the boundaries of these territories in the near future. The patterns obtained show
dramatic reductions in the extension of the Iberian submediterranean environment. Submediterranean conditions will probably
disappear from the areas where they currently reign, and it seems unlikely that any new, large submediterranean areas will
form by displacement towards higher altitudes. The outlook for the unique submediterranean vegetation of the Iberian Peninsula
is gloomy.
相似文献
Helios Sainz-OlleroEmail: |
99.
Deifilia Ahuatzi-chacón Guadalupe Ordorica-morales Nora Ruiz-ordaz Eliseo Cristiani-urbina Cleotilde Juárez-ramírez Juvencio Galíndez-mayer 《World journal of microbiology & biotechnology》2004,20(7):695-702
When Candida tropicalis was grown on phenol, catechol or resorcinol, the highest levels of specific activity of phenol hydroxylase (EC. 1.14.13.7) and catechol 1,2-dioxygenase (EC. 1.13.11.1) were attained with phenol. With the three aromatic compounds tested, the yeast cells exhibited sharp peaks of specific activity of both enzymes at particular incubation times. Phenol-induced cells containing high levels of both enzymes were capable of degrading rapidly and without delay 4-chlorophenol and 2,6-dichlorophenol, and to a lesser extend pentachlorophenol. However, the yeast could not grow on chlorophenols as major carbon and energy source. 相似文献
100.
Merz Felicitas Müller Mareike Taucher-Scholz Gisela Rödel Franz Stöcker Horst Schopow Kosta Laprell Laura Dehghani Faramarz Durante Marco Bechmann Ingo 《Radiation and environmental biophysics》2010,49(3):457-462
The aim of this interdisciplinary project is to establish slice culture preparations from rodents and humans as a new model
system for studying effects of X-rays and heavy ions within normal and tumor tissues. The advantage of such slice cultures
relies on the conservation of an organotypic environment, the easy treatment and observation by live-imaging microscopy, and
the independence from genetic immortalization strategies used to generate cell lines. Rat brains as well as human tumors were
cut into 300-μm-thick sections and cultivated in an incubator in a humidified atmosphere at 37°C. This is realized by a membrane-based
culture system with a liquid–air interface. With this system, it is possible to keep rodent slices viable for several months.
Human brain tumor slices remained vital for at least 21 days. Slices were irradiated with X-rays at the radiation facility
of the University Hospital in Frankfurt/Main at doses up to 40 Gy. Heavy ion irradiations were performed at GSI (Darmstadt)
with different ions, energies, and doses. The irradiated slices were analyzed by 3D-confocal microscopy following immunostaining
for DNA damage, microglia, and proliferation markers. The phosphorylated histone γH2AX proved to be suitable for the detection
of ion traversals in this system. 相似文献