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101.
Goutam Gupta Mukti H. Sarma Ramaswamy H. Sarma 《Journal of biomolecular structure & dynamics》2013,31(6):1457-1472
Abstract Antibiotic netropsin is known to bind specifically to A and T regions in DNA; the mode of binding being non-intercalative. Obviously, H-bonding between the proton donors of netropsin and acceptors N3 of A and 02 of T comes as a strong possibility which might render this specificity. In netropsin there could be 8 proton donors: four terminal amino groups and four internal imino groups. However, methylation of the terminal amino groups does not alter the binding affinity of netropsin to DNA—but the modification of the internal imino groups significantly lowers the binding affinity. Hence, the logical conclusion is that netropsin may specifically interact with A and T through H-bonding and in order to do so, it should approach the helix from the minor groove. The present paper provides experimental data which verify the conclusion mentioned above. Using poly(dA-dT)? poly(dA-dT) as a model system it was observed following a thorough theoretical stereochemical analysis that netropsin could bind to -(T-A-T) sequence of the polymer in the B-form through the minor groove by forming specific B-bonding. Models could be either right or left-handed B-DNA with a mono or dinucleotide repeat. By monitoring the 31P signals of free poly(dA-dT) ? poly(dA-dT) and netropsin-poly(dA-dT)? poly(dA-dT) complex we show that the drug changes the DNA structure from essentially a mononucleotide repeat to that of very dominant dinucleotide repeat; however the base- pairing in the DNA-drug complex remain to be Watson-Crick. Whether H-bonding is the specific mode of interaction was judged by monitoring the imino protons of netropsin in the presence of poly(dA-dT) ? poly(dA-dT). This experiment was conducted in 90% H2O + 10% D2O Using the time-shared long pulse. It was found that exchangeable imino protons of netropsin appear in the drug-DNA complex and disappear upon increasing the D2O content; thus confirming that H-bonding is indeed the specific mode of interaction. From these and several NOE measurements, we propose a structure for poly(dA-dT)? poly(dA-dT(-netropsin complex. In summary, experimental data indicate that netropsin binds to poly(dA-dT)? poly(dA-dT) by forming specific hydrogen bonds and that the binding interaction causes the structure to adopt a Watson-Crick paired dinucleotide repeat motif. The proposed hydrogen bonds can form only if the drug approaches the DNA from the minor groove. Within the NMR time scale the interaction between the ligand and DNA is a fast one. From the NOE experimental data, it appears that poly(dA-dT)? poly(dA-dT) in presence of netropsin exists as an equilibrium mixture of right- and left-handed B-DNA duplexes with a dinucleotide repeat—with a predominance of the left-handed form. The last conclusion is a soft one because it was very difficult to make sure the absence of spin diffusion. In a 400 base pairs long DNA duplex- drug complex (as used in this study), equilibrium between right and left-handed helices can also mean the existence of both helical domains in the same molecule with fast interchange between these domains or/and unhindered motion/propagation of these domains along the helix axis. 相似文献
102.
Zygomycosis was produced experimentally in 20 New Zealand white rabbits (Oryctolagus cuniculus) by intra-nasal administration
of spores of Absidia corymbifera. Infected animals showed dullness, depression, coughing and mucopurulent nasal discharge,
but no mortality. Haematology revealed no significant change in Hb and PCV, but leukocytosis due to neutrophilia in the initial
stages of the experiment. There was a significant increase in serum total proteins, creatinine, AST, ALT, total Igs and CICs.
A. corymbifera specific IgM and IgG antibodies were detected in the sera of the infected animals. Gross lesions consisted
of pneumonic consolidations of the antero-ventral lobes of the lungs. Microscopically, histology showed formation of pyogranulommas
in the lungs. Fungal elements typical of A. corymbifera were demonstrated in the tissues upto 15 days after infection by special
stains and confirmed by indirect immunoperoxidase. Re-isolation of the fungus from lungs was also achieved consistently up
to 15 days only. It was concluded that intra-nasal instillation of A. corymbifera in rabbits produced significant clinico-pathological
alterations with the lesions confined mainly to the lungs. In the present study, neither systemic dissemination of the disease
occurred nor were kidneys site of predilection as reported earlier.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
103.
104.
The aim of this work was to study the effect of a high voltage pulsed electric field (PEF) on the inactivation of E. coli in cranberry juice to achieve the regulatory requirement of a 5‐log reduction in the microbial count. PEF processing involved the application of high voltage pulses to liquid or semi‐solid materials, placed between two electrodes at ambient, sub‐ambient, or supra‐ambient temperature. In this work, cranberry juice, inoculated with E. coli was subjected to 60 pulses in the voltage range of 5 to 40 kV/cm. The experiments were carried out at 20 °C. The temperature rise was less than 2 °C at the average treatment time of 80 s. PEF is an emerging non‐thermal technology for food preservation that retains the natural taste of food. It has mainly been applied to improve the shelf life of such foods as milk, liquid eggs and fruit juices. 相似文献
105.
106.
The skin cells chiefly depend on carbohydrate metabolism for their energy requirement during cutaneous wound healing. Since the glucose metabolism is greatly hampered in diabetes and this might affect wound repair process. This prompted us to investigate the intermediate steps of energy metabolism by measuring enzyme activities in the wound tissues of normal and streptozotocin-induced diabetic rats following excision-type of cutaneous injury. The activities of key regulatory enzymes namely hexokinase (HK), phosphofructokinase (PFK), lactate dehydrogenase (LDH), citrate synthase (CS) and glucose-6 phosphate dehydrogenase (G6PD) have been monitored in the granulation tissues of normal and diabetic rats at different time points (2, 7, 14 and 21 days) of postwounding. Interestingly, a significant alteration in all these enzyme activities was observed in diabetic rats. The activity of PFK was increased but HK, LDH and CS showed a decreased activity in the wound tissue of diabetics as compared to normal rats. However G6PD exhibited an elevated activity only at early stage of healing in diabetic rats. Thus, the results suggest that significant alterations in the activities of energy metabolizing enzymes in the wound tissue of diabetic rats may affect the energy availability for cellular activity needed for repair process and this may perhaps be one of the factor responsible for impaired healing in these subjects. (Mol Cell Biochem 270: 71–77, 2005) 相似文献
107.
K. V. Chowdari A. P. Davierwala V. S. Gupta P. K. Ranjekar O. P. Govila 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1998,97(1-2):154-162
The potential of DNA markers such as microsatellites, minisatellites and RAPDs was investigated in pearl millet [Pennisetum glaucum (L.) R. Br] with respect to their abundance and variability. Southern analysis, using 22 different di-, tri-, tetra- and
penta-oligonucleotide probes and five minisatellite probes, identified (GATA)4 as the most useful probe for the detection of multiple polymorphic fragments among pearl millet cultivars and landraces from
India. The clustering patterns of pearl millet cultivars and landraces based on (GATA)4 and RAPD (randomly amplified polymorphic DNA) markers differed. The landraces, representing eight states in India, could
not be grouped based on their geographical distribution with the DNA markers. RAPD analysis revealed a high degree of genetic
diversity among the cultivars and landraces employed in this study. The probability of an identical match by chance for any
two genotypes using (GATA)4 and RAPDs was 3.02×10-20 for cultivars and 5.2×10-9 for landraces. The microsatellite (GATA)4 and RAPDs provide useful tools for genotype identification and for the assessment of genetic relationships in pearl millet.
Received: 19 October 1997 / Accepted: 9 December 1997 相似文献
108.
OBJECTIVE: To assess the utility of indigenously prepared cell blocks (CBs) as an adjunct to a conventional smear test in providing a reliable diagnosis of clinically suspicious cervical cancer in resource-limited settings. METHODS: Eighty-six clinically suspicious cervical cancer cases underwent a conventional smear test, CB preparation from residual cellular samples and biopsies at the same sitting. Correlations were performed between these modalities in order to derive the sensitivity and specificity of the CB technique to diagnose cervical cancer. OBSERVATION & RESULTS: Out of 86 clinically suspicious cervical cancers, 72 (83.7%), 70 (81.4%) and 67 (77.9%) cases were diagnosed as malignant on tissue biopsies, CBs and smears respectively. CB-biopsy agreement in the diagnosis of malignancy was feasible in 87.5% of the cases while CB-Pap smear agreement was feasible in 92.5% of the cases. Sensitivity and specificity of CB preparation to diagnose malignancy was 92.5% and 100%, respectively, when the smear was taken as the reference test (excluding the unsatisfactory smears). When biopsy was taken as the gold standard, the sensitivity and specificity of CBs were 87.5% and 100% respectively (excluding the unsatisfactory biopsies). In 8/19 cases where the smear diagnoses were either unsatisfactory or atypical squamous cells/atypical glandular cells, CBs picked up malignant lesions. CONCLUSION: CBs prepared from the residual cellular sample of conventional cervical scrapes augment the sensitivity of the smear test. When used as an adjunct to the smear, CBs aid in providing a reliable diagnosis of cervical cancer in the majority of the clinically suspected cases and thus the biopsy load can be reduced significantly in resource-poor settings. 相似文献
109.
Jun Zhang Kevin A. Fengler John L. Van Hemert Rajeev Gupta Nick Mongar Jindong Sun William B. Allen Yang Wang Benjamin Weers Hua Mo Renee Lafitte Zhenglin Hou Angela Bryant Farag Ibraheem Jennifer Arp Kankshita Swaminathan Stephen P. Moose Bailin Li Bo Shen 《Plant biotechnology journal》2019,17(12):2272-2285
110.
P Lemansky D K Gupta S Meyale G Tucker A M Tartakoff 《Molecular and cellular biology》1991,11(8):3879-3885
Essentially all eukaryotic cells, including murine lymphomas, express surface proteins, such as Thy-1, which are anchored by a phosphoinositol mannolipid. Putative mannolipid anchor precursors can be detected in these cells. Six distinct Thy-1-negative lymphoma mutants lack complete mannolipids, and three mutants synthesize atypical mannolipids. The absence of complete mannolipids can account for the lack of expression of multiple mannolipid-anchored proteins and may also account for the lack of lipid anchoring in the human disease paroxysmal nocturnal hemoglobinuria. Structural information on the mannolipids of wild-type and mutant cells indicates that anchor biosynthesis in these cells may involve both transmembrane flip-flop of intermediates and a deacylation step. 相似文献