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991.
Trenbolone (TRE) is a steroid used by veterinarians on livestock to increase appetite and body weight. The use of TRE has been restricted because of its harmful side effect for consumers. To effectively control TRE residue in food and food product, a rapid and convenient immunoassay was developed by preparing an anti-TRE monoclonal antibody. The immunogen and coating antigen were prepared by coupling TRE hapten with carrier proteins via 1-ethyl-3-(dimethylaminopropyl)carbodiimide hydrochloride (EDC) method. The optimized method gave an average IC50 value of 0.323 ng mL−1 towards TRE and an average detection limit (LOD) of 0.06 ng mL−1, which is much lower than the maximum residue levels (2.0 ng g−1) accepted by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). The specificity of the antibody was evaluated by measuring cross-reactivity of six structurally related compounds, including 19-nortestosterone (9.7%), testosterone (0.13%), methyltestosterone (<0.01%), methandrostenolone (<0.01%), (+)-dehydroisoandrosterone (<0.001%) and β-estradiol (<0.001%). The recovery rates of the test in detection of TRE-fortified animal tissue, urine and animal feed samples were in the range of 81.3-89.4%, while the intra- and inter-assay coefficients of variation were less than 12.0%. 相似文献
992.
993.
Xu J Cao T Zhang M Li Z Zhang M Ni L Xie P 《Rapid communications in mass spectrometry : RCM》2011,25(21):3267-3273
Stable isotopic turnover with isotopic change due to growth and metabolic tissue replacement associated with a change in environmental conditions is a critical aspect of the use of stable isotope analyses as time-integrating tracers of resource-consumer interactions. However, stable isotopic turnover in plants remains poorly understood compared with those of animals, and here we used continuous flow elemental analyzer-isotopic ratio mass spectrometry (EA-IRMS) to analyse the turnover of stable carbon and nitrogen isotopes in a submersed macrophyte (Vallisneria natans) after transplantation to hypereutrophic and mesoeutrophic treatments in a field mesocosm experiment. The direction and magnitude of the isotopic shifts of V. natans were suggested to be determined by the inorganic nutrient availability and its isotopic content in the different treatments. Based on the modelling results of turnover, the contribution of growth to the isotopic turnover was as high as those observed in various aquatic ectotherms. However, the contribution of metabolism was also considerable, especially for nitrogen in the hypereutrophic treatment, which was argued to be a response, co-occurring with growth inhabitation and biochemical disorder of V. natans, to the stress induced by the eutrophication. Our results indicated that isotope turnover in a macrophyte is a feasible technique for estimating its ecophysiological conditions in the natural environment, and that it may facilitate understanding of isotopic data in field studies of food web and habitat restoration under eutrophic conditions. 相似文献
994.
Hong J Zhang L Yu X Li M Zhang Z Zheng P Nishiura M Hou Z Zhou X 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(7):2130-2137
Unsolvated, trinuclear, homometallic, rare-earth-metal multimethyl methylidene complexes [{(NCN)Ln(μ(2)-CH(3))}(3)(μ(3)-CH(3))(μ(3)-CH(2))] (NCN = L = [PhC{NC(6)H(4)(iPr-2,6)(2)}(2)](-); Ln = Sc (2a), Lu (2b)) have been synthesized by treatment of [(L)Ln{CH(2)C(6)H(4)N(CH(3))(2)-o}(2)] (Ln = Sc (1a), Lu (1b)) with two equivalents of AlMe(3) in toluene at ambient temperature in good yields. Treatment of 1 with three equivalents of AlMe(3) gives the heterometallic trinuclear complexes [(L)Ln(AlMe(4))(2)] (Ln = Sc (3a), Lu (3b)) in good yields. Interestingly, 2 can also be generated by recrystallization of 3 in THF/toluene, thereby indicating that the THF molecule can also induce C-H bond activation of 2. Reaction of 2 with one equivalent of ketones affords the trinuclear homometallic oxo-trimethyl complexes [{(L)Ln(μ(2) -CH(3))}(3) (μ(3)-CH(3))(μ(3)-O)] (Ln = Sc(4a), Lu(4b)) in high yields. Complex 4b reacts with one equivalent of cyclohexanone to give the methyl abstraction product [{(L)Lu(μ(2) -CH(3) )}(3) (μ(3) -OC(6)H(9))(μ(3)-O)] (5b), whereas reaction of 4b with acetophenone forms the insertion product [{(L)Lu(μ(2)-CH(3))}(3){μ(3)-OCPh(CH(3))(2)}(μ(3)-O)] (6b). Complex 4a is inert to ketone under the same conditions. All these new complexes have been characterized by elemental analysis, NMR spectroscopy, and confirmed by X-ray diffraction determination. 相似文献
995.
996.
A simple and stability-indicating reverse phase high performance liquid chromatographic (RP-HPLC) method was developed and validated for the determination of olanzapine (OLN) and related impurities in bulk drugs. Eight impurities were characterized respectively, and particularly a new process impurity from OLN synthesis was structurally confirmed as 1-(5-methylthionphen-2-yl)-1H-benzimidazol-2(3H)-one (Imp-7) by X-ray single crystal diffraction, MS, (1)H NMR, (13)C NMR and HSQC. A mechanism of formation pathway for Imp-7 was proposed. Optimum separation for OLN and eight related impurities was carried out on an Agilent Octyldecyl silica column (TC-C(18), 4.6 mm × 250 mm, 5 μm) using a gradient HPLC method. The method was validated with respect to specificity, linearity, accuracy, precision, LOD and LOQ. Regression analysis showed good correlation (r(2) > 0.9985) between the investigated component concentrations and their peak areas within the test ranges for OLN and eight impurities. The repeatability and intermediate precision, expressed as RSD, were less than 1.74%. The proposed stability-indicating method was suitable for routine quality control and drug analysis of OLN in bulk drugs. 相似文献
997.
Lykourinou V Chen Y Wang XS Meng L Hoang T Ming LJ Musselman RL Ma S 《Journal of the American Chemical Society》2011,133(27):10382-10385
Microperoxidase-11 has for the first time been successfully immobilized into a mesoporous metal-organic framework (MOF) consisting of nanoscopic cages and it demonstrates superior enzymatic catalysis performances compared to its mesoporous silica counterpart. 相似文献
998.
Electrochemical activities of typically electrochemical targets at three kinds of modified carbon electrodes, i.e. carbon ionic liquid electrode (CILE), graphene/carbon paste electrode (CPE), and ionic liquid-functionalized graphene (IL-graphene)/CPE, were compared in detail. The redox processes of the probes at IL-graphene/CPE were faster than those at CILE and graphene/CPE from cyclic voltammetry. An electrochemical method for the simultaneous determination of guanine and adenine was described with detection limits of 6.5 × 10−8 mol L−1 (guanine) and 3.2 × 10−8 mol L−1 (adenine). Single A → G mutation of sequence-specific DNA could be discriminated by the IL-graphene/CPE. 相似文献
999.
A novel hyperbranched conjugated chemosensor with bipyridyl groups as periphery groups(BPY-HPV) was synthesized.BPY-HPV was highly sensitive to metal ions(Cu2+,Ni2+) for the strong coordination interaction(Ksv at the order of 107 mol-1 L) monitored by fluorescence spectroscopy.Moreover,by hydrogen bonds and charge transfer interaction,BPY-HPV shows strong interaction with 1,1,2,2-tetrachloroethane whatever in CH2Cl2(Ksv~106 mol-1 L) or film. 相似文献
1000.
Lead nanotapes were synthesized in liquid ammonia solvent in the presence of sodium metal at low temperature.The process was template free.Transmission electron microscopy(TEM) observations and X-ray diffraction(XRD) characterizations revealed that the as-prepared Pb nanotapes have average diameters in the range of 40-50 nm.and lengths up to several hundred nanometers, and exhibit cubic crystal structures. 相似文献