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991.
Wei‐Guang Wang Zhao‐Yuan Wu Rui Chen Hai‐Zhou Li Hong‐Mei Li Yuan‐Dan Li Rong‐Tao Li Huai‐Rong Luo 《化学与生物多样性》2013,10(6):1061-1071
Four highly acylated diterpenoids, designated as pierisformotoxins A–D ( 1 – 4 , resp.), along with 26 known compounds, were isolated from the flowers of Pieris formosa. Among them, pierisformotoxins A and B ( 1 and 2 , resp.) were new highly acylated grayanane diterpenoids, of which the five‐membered ring A has undergone an oxidative cleavage between C(3) and C(4), followed by lactonization, to give rise to a five‐membered lactone ring between C(3) and C(5), differing from the previously reported grayanane diterpenoids with a 5/7/6/5 ring system. Results of the cAMP‐regulation‐activity assay showed that pierisformotoxin C ( 3 ) at 10 μM (inhibitory ratio (IR): 10.1%) or 2 μM (9.8%), and pierisformotoxin B ( 2 ) at 50 μM (13.9%) significantly decreased the cAMP level in N1E‐115 neuroblastoma cells (p<0.05). 相似文献
992.
Ren‐Hua Chen Yi‐Gang Li Kun‐Li Jiao Peng‐Pai Zhang Yu Sun Li‐Ping Zhang Xiang‐Fei Fong Wei Li Yi Yu 《Journal of cellular and molecular medicine》2013,17(5):608-616
The expression of the chemorepellent Sema3a is inversely related to sympathetic innervation. We investigated whether overexpression of Sema3a in the myocardial infarction (MI) border zone could attenuate sympathetic hyper‐innervation and decrease the vulnerability to malignant ventricular tachyarrhythmia (VT) in rats. Survived MI rats were randomized to phosphate buffered saline (PBS, n = 12); mock lentivirus (MLV, n = 13) and lentivirus‐mediated overexpression of Sema3a (SLV, n = 13) groups. Sham‐operated rats served as control group (CON, n = 20). Cardiac function and electrophysiological study (PES) were performed at 1 week later. Blood and tissue samples were collected for histological analysis, epinephrine (EPI), growth‐associated factor 43 (GAP43) and tyrosine hydroxylase (TH) measurements. QTc intervals were significantly shorter in SLV group than in PBS and MLV groups (168.6 ± 7.8 vs. 178.1 ± 9.5 and 180.9 ± 8.2 ms, all P < 0.01). Inducibility of VT by PES was significantly lower in the SLV group [30.8% (4/13)] than in PBS [66.7% (8/12)] and MLV [61.5% (8/13)] groups (P < 0.05). mRNA and protein expressions of Sema3a were significantly higher and the protein expression of GAP43 and TH was significantly lower at 7 days after transduction in SLV group compared with PBS, MLV and CON groups. Myocardial EPI in the border zone was also significantly lower in SLV group than in PBS and MLV group (8.73 ± 1.30 vs. 11.94 ± 1.71 and 12.24 ± 1.54 μg/g protein, P < 0.001). Overexpression of Sema3a in MI border zone could reduce the inducibility of ventricular arrhythmias by reducing sympathetic hyper‐reinnervation after infarction. 相似文献
993.
Zhensheng Liu Erich M Sturgis Qingyi Wei 《Journal of cellular and molecular medicine》2013,17(7):873-878
Recently, several studies have investigated the association between a newly reported rare functional single nucleotide polymorphism (SNP) in TP53 (rs78378222) and cancer risk, but generated inconsistent findings. The present study further investigated this association with risk of melanoma, squamous cell carcinoma of head and neck (SCCHN) and lung cancer. Using volunteers of non‐Hispanic Whites recruited for three large case–control studies, we genotyped the TP53 rs78378222 SNP in 1329 patients with melanoma, 1096 with SCCHN, 1013 with lung cancer and 3000 cancer‐free controls. Overall, we did not observe any variant homozygotes in this study population, nor significant associations between the TP53 rs78378222AC genotype or C allele and risk for melanoma (P = 0.680 and 0.682 respectively) and lung cancer (P = 0.379 and 0.382 respectively), but a protection against SCCHN (P = 0.008 and 0.008 respectively), compared with the AA genotype or A allele. An additional meta‐analysis including 19,423 cancer patients and 54,050 controls did not support such a risk association either. Our studies did not provide statistical evidence of an association between this rare TP53 variant and increased risk of melanoma, nor of lung cancer, but a possible protection against SCCHN. 相似文献
994.
Wei Gao Jiqing Jiao Huajie Feng Xiaopeng Xuan Liuping Chen 《Journal of molecular modeling》2013,19(3):1273-1283
A combined and sequential use of quantum mechanical (QM) calculations and classical molecular dynamics (MD) simulations was made to investigate the σ and π types of hydrogen bond (HB) in benzene-water and pyrrole-water as clusters and as their liquid mixture, respectively. This paper aims at analyzing similarities and differences of these HBs resulted from QM and MD on an equal footing. Based on the optimized geometry at ωb97xD/aug-cc-pVTZ level of theory, the nature and property of σ and π types of HBs are unveiled by means of atoms in molecules (AIM), natural bond orbital (NBO) and energy decomposition analysis (EDA). In light of the above findings, MD simulation with OPLS-AA and SPC model was applied to study the liquid mixture at different temperatures. The MD results further characterize the behavior and structural properties of σ and π types HBs, which are somewhat different but reasonable for the clusters by QM. Finally, we provide a reasonable explanation for the different solubility between benzene/water and pyrrole/water. Figure
The σ and π types of hydrogen bond as benzene-water and pyrrole-water clusters in gas; Snapshot of benzene/water and pyrrole/water as 1:1 liquid mixture extracted from the MD simulations 相似文献
995.
Molecular dynamics study on the correlation between structure and sensitivity for defective RDX crystals and their PBXs 总被引:1,自引:0,他引:1
Ji Jun Xiao Song Yuan Li Jun Chen Guang Fu Ji Wei Zhu Feng Zhao Qiang Wu He Ming Xiao 《Journal of molecular modeling》2013,19(2):803-809
Molecular dynamics simulation was applied to investigate the sensitivities of perfect and defective RDX (cyclotrimethylene trinitramine) crystals, as well as their PBXs (polymer-bonded explosives) with the polymeric binder F2311, in the NPT (constant number of particles, constant pressure, constant temperature) ensemble using the COMPASS force field. Five kinds of defects—two dislocations, one vacancy, and two types of doping—were considered separately. The bond length distribution and the maximum (L max) and average (L ave) bond lengths of the N–NO2 trigger bonds in RDX were obtained and their relationships to the sensitivities of RDX and PBXs are discussed. L max was found to be an important structural parameter for judging the relative sensitivity, and defects were observed to have little effect on the sensitivities of PBXs, due to the strong desensitizing effect of the polymer F2311. 相似文献
996.
Yang Bai Zhong-Jun Zhou Jia-Jun Wang Ying Li Di Wu Wei Chen Zhi-Ru Li Chia-Chung Sun 《Journal of molecular modeling》2013,19(9):3983-3991
How to generate a non-zero first hyperpolarizability for a centrosymmetric molecule is a challenging question. In this paper, an external (pump) electric field is used to make a centrosymmetric benzene molecule generate a non-zero value of the electric field induced first hyperpolarizability (β F ). This comes from the centrosymmetry breaking of electron cloud. Two interesting rules are exhibited. (1) β F is anisotropic for different directional fields (F i, i?=?X, Y, Z). (2) The field dependence of β F is a non-monotonic function, and an optimum external electric field causes the maximum value of β F . The largest first hyperpolarizability β F reaches the considerable level of 3.9?×?105 a.u. under F Y?=?330?×?10?4 a.u. for benzene. The external electric field effects on non-centrosymmetric edge-modified graphene ribbon H2N-(3,3)ZGNR-NO2 was also studied in this work. The first hyperpolarizability reaches as much as 2.1?×?107 a.u. under F X?=?600?×?10?4 a.u. for H2N-(3,3)ZGNR-NO2. We show that the external electric field can not only create a non-zero first hyperpolarizability for centrosymmetric molecule, but also remarkably enhance the first hyperpolarizability for a non-centrosymmetric molecule. 相似文献
997.
Qi Liang Lu Wen Jun Song Jun Wei Meng Jian Guo Wan 《Journal of molecular modeling》2013,19(3):1205-1209
The possibility of a new endohedral fullerene with a trapped aluminum carbide cluster, Al4C @C80-I h , was theoretical investigated. The geometries and electronic properties of it were investigated using density functional theory methods. The Al4C unit formally transfers six electrons to the C80 cage which induces stabilization of Al4C@C80. A favorable binding energy, relatively large HOMO-LUMO gap, electron affinities and ionization potentials suggested the Al4C@C80 is rather stable. The analysis of vertical ionization potential and vertical electron affinity indicate Al4C@C80 is a good electron acceptor. Figure
An endohedral fullerene with a trapped aluminum carbide cluster, Al4C @C80-I h , was investigated using density functional theory. A favorable binding energy, relatively large HOMO-LUMO gap, electron affinities and ionization potentials suggested it is rather stable 相似文献
998.
Min Cen Jian Fen Fan Dong Yan Liu Xue Zeng Song Jian Liu Wei Qun Zhou He Ming Xiao 《Journal of molecular modeling》2013,19(2):601-611
Molecular dynamic (MD) simulations have been performed to study the behaviors of ten kinds of cyclo-hexa-peptides (CHPs) composed of amino acids with the diverse hydrophilic/hydrophobic side chains at the water/cyclohexane interface. All the CHPs take the “horse-saddle” conformations at the interface and the hydrophilicity/hydrophobicity of the side chains influences the backbones’ structural deformations. The orientations and distributions of the CHPs at the interface and the differences of interaction energies (ΔΔE) between the CHPs and the two liquid phases have been determined. RDF analysis shows that the H-bonds were formed between the OC atoms of the CHPs’ backbones and Hw atoms of water molecules. N atoms of the CHPs’ backbones formed the H-bonds or van der Waals interactions with the water solvent. It was found that there is a parallel relationship between ΔΔE and the lateral diffusion coefficients (D xy ) of the CHPs at the interface. The movements of water molecules close to the interface are confined to some extent, indicating that the dynamics of the CHPs and interfacial water molecules are strongly coupled. Figure
Scheme of the ten kinds of CHPs formed by even alternating D- and L- amino acids with the different hydrophilic/hydrophobic side chains. The letters in the parentheses stand for the abbreviations of the composed amino acids in the CHPs 相似文献
999.
Xiao Ran Zhao Yu Jie Wu Juan Han Qian Jin Shen Wei Jun Jin 《Journal of molecular modeling》2013,19(1):299-304
MP2(full)/aug-cc-pVDZ(-PP) computations predict that new triangular bonding complexes (where X? is a halide and H–C refers to a protic solvent molecule) consist of one halogen bond and two hydrogen bonds in the gas phase. Carbon tetrabromide acts as the donor in the halogen bond, while it acts as an acceptor in the hydrogen bond. The halide (which commonly acts as an acceptor) can interact with both carbon tetrabromide and solvent molecule (CH3CN, CH2Cl2, CHCl3) to form a halogen bond and a hydrogen bond, respectively. The strength of the halogen bond obeys the order CBr4???Cl? > CBr4???Br? > CBr4???I?. For the hydrogen bonds formed between various halides and the same solvent molecule, the strength of the hydrogen bond obeys the order C-H???Cl? > C-H???Br? > C-H???I?. For the hydrogen bonds formed between the same halide and various solvent molecules, the interaction strength is proportional to the acidity of the hydrogen in the solvent molecule. The diminutive effect is present between the hydrogen bonds and the halogen bond in chlorine and bromine triangular bonding complexes. Complexes containing iodide ion show weak cooperative effects. Figure
The triangular bonding complexes consisting of halogen bond and hydrogen bonds were predict in the gas phase by computational quantum chemistry. 相似文献
1000.
The photophysical properties of five blue light-emitting polymers based on spirobifluorene applied in polymer light-emitting diodes (PLED) materials have been studied by quantum chemistry. In order to understand the intrinsic reasons for the different performances displayed by the polymers, we carried out density functional theory (DFT) and Marcus theory investigations on their oligomers in terms of structure and properties stability, absorption and emission properties, and carrier injection and transport properties. Especially, some important parameters which had not been reported to our knowledge were given in this contribution, such as the ionization potentials (IPs), electron affinities (EAs), reorganization energies (λ), k e /k h (the ratio between the electron transfer rate (k e ) and hole transfer rate (k h )), and the radiative lifetimes (τ). The main results indicate that the co-oligomers of PCC-1, PCC-2, and PCC-3 with push-pull interactions produced by the existing D-A segments have better carrier injection and transport properties than the oligomers of PSF and PCF. Especially PCC-2 co-oligomer, its large radiation lifetime (7.46 ns) and well balanced and adequate carrier transport guarantee its champion performance for PLED. The calculated results coincide with the experimental ones. Besides, PNF structurally similar to PCC-2 has similar photoelectric properties to PCC-2 in theory, and the fluorescence emission of PNF co-oligomer is superior to PCC-2 co-oligomer. Therefore, we predict that PNF is a promising candidate for PLED. 相似文献