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81.
Evidence that microbial sulphate reduction is mainly responsible for the formation of the natron (hydrated Na2 CO3 ) deposits in Wadi Natrûn is presented. The sulphate in the infiltrating water is reduced during passage through the surrounding waterlogged soil and the bicarbonate formed is later concentrated by evaporation in the lakes. 相似文献
82.
Basu Samar Kindahl Hans Harvey Denis Betteridge Keith J. 《Acta veterinaria Scandinavica》1987,28(3-4):409-420
The metabolism of PGF2α in cattle results initially in the formation of 15-keto-13,14-dihydro-PGF2α (15-ketodihydro-PGF2α) and later the 11-ketotetranor PGF metabolites. Both types of metabolites appear in the peripheral circulation and finally the 11-ketotetranor PGF metabolites are found in large quantities in the urine in a species-related pattern. Several approaches can be made to the quantitative analysis of PGF2α release during reproductive studies. First, assay of the 15-ketodihydro-PGF2α metabolite in the peripheral circulation; second, analysis of the longer-lived 11-ketotetranor PGF metabolites in the peripheral circulation; and finally analysis of the latter metabolites in the urine. The antibodies used in radioimmunoassays of both types of metabolites of PGF2α were found to be specific and the results agree well with those obtained earlier by mass spectrometric analysis. The assay of 11-ketotetranor PGF metabolites was used to study the excretion of urinary metabolites in the cow after i.v. infusion of PGF2α and also during the normal estrous cycle and early pregnancy. These studies suggest that 11-ketotetranor PGF metabolites in cow urine serve as a good parameter of PGF2α release, especially for long–term studies, but when a precise pattern of PGF2α release is required, measurement of 15-ketodihydro-PGF2α levels in frequently collected plasma samples is preferable. 相似文献
83.
M Rizk J H Pavlovitch L Didierjean J H Saurat S Balsan 《Biochemical and biophysical research communications》1984,123(1):230-237
The amount of skin calcium-binding protein, evaluated using a sensitive radioimmunoassay and indirect immunofluorescence, was decreased in vitamin-D deficient rats and increased after one week vitamin D3 or 1 alpha-hydroxyvitamin D3 treatment. In vitamin D replete and in vitamin D-deficient animals, skin calcium-binding protein was not sensitive to changes in dietary and/or serum calcium concentrations. These results indicate that this protein is different from other calcium-binding proteins such as parvalbumin and calmodulin which are not vitamin D-dependent, and also different from intestinal calcium-binding protein which, in D replete animals, is sensitive to changes in dietary and serum calcium concentrations. Skin calcium-binding protein may, therefore, represent a new class of vitamin D-dependent protein. 相似文献
84.
85.
Salhah D. Al-Qahtani Razan M. Snari Kholood Alkhamis Nada M. Alatawi Mona Alhasani Samar Y. Al-nami Nashwa M. El-Metwaly 《Luminescence》2022,37(3):479-489
Long-persistent phosphorescent smart paints have the ability to continue glowing in the dark for a prolonged time period to function as energy-saving products. Herein, new epoxy/silica nanocomposite paints were prepared with different concentrations of lanthanide-doped aluminate nanoparticles (LAN; SrAl2O4:Eu2+,Dy3+). The LAN pigment was firstly coated with silicon dioxide (SiO2) utilizing the heterogeneous precipitation technique to provide LAN-encapsulated between SiO2 nanoparticles (LAN@SiO2). The epoxy/silica/lanthanide-doped aluminate nanoparticles (ESLAN) nanocomposite paints were coated on steel. The prepared ESLAN paints were studied by transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray fluorescence (XRF) analysis, and energy-dispersive X-ray spectroscopy (EDS). The transparency and coloration properties of the nanocomposite coated films were explored by CIE Lab parameters and photoluminescence spectra. The ultraviolet-induced luminescence properties of the transparent coated films demonstrated greenish phosphorescence at 518 nm upon excitation at 368 nm. Both hardness and hydrophobic activities were investigated. The anticorrosion activity of the nanocomposite films coated onto mild steel substrates immersed in aqueous sodium chloride (NaCl(aq)) (3.5%) was studied by electrochemical impedance spectroscopy (EIS). The silica-containing coatings were monitored to exhibit anticorrosion properties. Additionally, the nanocomposite films with LAN@SiO2 (25%) exhibited the optimized long-lasting luminescence properties in the dark for 90 min. The nanocomposite films showed highly reversible and durable long-lived phosphorescence. 相似文献
86.
The purpose of this study was to formulate topically effective controlled release ophthalmic acetazolamide liposomal formulations.
Reverse-phase evaporation and lipid film hydration methods were used for the preparation of reversephase evaporation (REVs)
and multilamellar (MLVs) acetazolamide liposomes consisting of egg phosphatidylcholine (PC) and cholesterol (CH) in the molar
ratios of (7∶2), (7∶4), (7∶6), and (7∶7) with or without stearylamine (SA) or dicetyl phosphate (DP) as positive and negative
charge inducers, respectively. The prepared liposomes were evaluated for their entrapment efficiency and in vitro release.
Multilamellar liposomes entrapped greater amounts of drug than REVs liposomes. Drug loading was increased by increasing CH
content as well as by inclusion of SA. Drug release rate showed an order of negatively charged > neutral > positively charged
liposomes, which is the reverse of the data of drug loading efficiency. Physical stability study indicated that approximately
89%, 77%, and 69% of acetazolamide was retained in positive, negative, and neutral MLVs liposomal formulations up to a period
of 3 months at 4°C. The intraocular pressure (IOP)-lowering activity of selected acetazolamide liposomal formulations was
determined and compared with that of plain liposomes and acetazolamide solution. Multilamellar acetazolamide liposomes revealed
more prolonged effect than REVs liposomes. The positively charged and neutral liposomes exhibited greater lowering in IOP
and a more prolonged effect than the negatively charged ones. The positive multilamellar liposomes composed of PC:CH:SA (7:4:1)
molar ratio showed the maximal response, which reached a value of −7.8±1.04 mmHg after 3 hours of topical administration.
Published: January 5, 2007 相似文献
87.
Riaz N Nawaz SA Mukhtar N Malik A Afza N Ali S Ullah S Muhammad P Choudhary MI 《化学与生物多样性》2007,4(1):72-83
Bractin A (=(2S,3S,4R,5E)-2-{[(2R)-2-hydroxydodecanoyl]amino}triacont-5-ene-1,3,4-triol; 1) and bractin B (=(2S,3S,4R,5E,8E)-2-{[(2R)-2-hydroxyhexacosanoyl]amino}pentadeca-5,8-diene-3,4,15-triol 1-O-beta-D-glucopyranoside; 2), new sphingolipids, and bractic acid (=(5Z,10Z,15Z)-2-decyl-4,7,8,12,13,17,18-heptahydroxy-20,23-dioxopentacosa-5,10,15-trienoic acid; 3), a long-chain polyhydroxy acid, were isolated from the whole plant Ajuga bracteosa along with four known diterpenoids 4-7. Their structures were deduced by spectral studies including 1D- and 2D-NMR spectroscopy. Compounds 1-3 displayed inhibitory potential against enzyme lipoxygenase, while compounds 4-7 inhibited cholinesterase enzymes in a concentration-dependent manner with IC(50) values in the range 10.0-33.0, 14.0-35.2, and 10.0-19.0 microM for lipoxygenase, acetylcholinesterase, and butyrylcholinesterase, respectively. Lineweaver-Burk, and Dixon plots, and their secondary replots indicated that all compounds exhibit non-competitive type of inhibition with K(i) values in the range of 9.5-35.2, 15.2-36.0, and 11.6-20.5 microM, for lipoxygenase, acetylcholinesterase, and butyrylcholinesterase, respectively. 相似文献
88.
Bhushan S Kumar A Malik F Andotra SS Sethi VK Kaur IP Taneja SC Qazi GN Singh J 《Apoptosis : an international journal on programmed cell death》2007,12(10):1911-1926
A triterpenediol (TPD) comprising of isomeric mixture of 3α, 24-dihydroxyurs-12-ene and 3α, 24-dihydroxyolean-12-ene from
Boswellia serrata induces apoptosis in cancer cells. An attempt was made in this study to investigate the mechanism of cell death by TPD in
human leukemia HL-60 cells. It inhibited cell proliferation with IC50 ∼ 12 μg/ml and produced apoptosis as measured by various biological end points e.g. increased sub-G0 DNA fraction, DNA ladder
formation, enhanced AnnexinV-FITC binding of the cells. Further, initial events involved massive reactive oxygen species (ROS)
and nitric oxide (NO) formation, which were significantly inhibited by their respective inhibitors. Persistent high levels
of NO and ROS caused Bcl-2 cleavage and translocation of Bax to mitochondria, which lead to loss of mitochondrial membrane
potential (Δψm) and release of cytochrome c, AIF, Smac/DIABLO to the cytosol. These events were associated with decreased expression of
survivin and ICAD with attendant activation of caspases leading to PARP cleavage. Furthermore, TPD up regulated the expression
of cell death receptors DR4 and TNF-R1 level, leading to caspase-8 activation. These studies thus demonstrate that TPD produces
oxidative stress in cancer cells that triggers self-demise by ROS and NO regulated activation of both the intrinsic and extrinsic
signaling cascades. 相似文献
89.
90.
Bhahwal Ali Shah Rajbir Kaur Pankaj Gupta Ajay Kumar Vijay Kumar Sethi Samar Singh Andotra Jaswant Singh Ajit Kumar Saxena Subhash Chandra Taneja 《Bioorganic & medicinal chemistry letters》2009,19(15):4394-4398
Analogues of parthenin were synthesized by substitutions at different reaction centres to establish a structure–activity relationship (SAR). Some of the molecules have displayed significant cytotoxicity in human cervical carcinoma (HeLa) and human myeloid leukemia (HL-60) cells. A few of the compounds also induced apoptosis in HL-60 cells measured in terms of sub-Go/G1 DNA fraction. Also one of the lead molecules has been shown to be the inhibitor of both telomerase and topoisomerase-II. 相似文献