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31.
High molar-mass aromatic polyamides were obtained from 7,7'-bis(4-carboxyphenoxy)-4,4,4′,4′-tetramethyl-2,2′-spirobichroman, a novel dicarboxylic acid monomer, by direct polycondensation reaction in N-methyl-2-pyrrolidone (NMP) with various aromatic diamines, using triphenyl phosphite and pyridine as condensing agents. Polyamides having inherent viscosities of 0,73–1,08 dL/g were obtained in quantitative yield. All the polyamides, even that derived from benzidine, are completely amorphous and readily soluble in a variety of organic solvents such as NMP, N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), and m-cresol. Their solutions can be cast into transparent, flexible and tough films. All the polyamides show distinct glass transitions in the range of 182–235°C on their differential scanning calorimetry (DSC) traces. The 10% weight loss temperatures in nitrogen and air are above 416 and 422°C, respectively. 相似文献
32.
Chin-Ping Yang Ju-Ming Cheng Sheng-Huei Hsiao 《Macromolecular chemistry and physics.》1992,193(2):445-453
An imide-ring-containing dicarboxylic acid, N,N′-(9-fluorenylidenedi-1,4-phenylene)diphthal-imide-4-carboxylic acid ( 1 ), was prepared by condensation of trimellitic anhydride and 9,9-bis(4-aminophenyl)fluorene. A series of new aromatic cardo poly(amide-imide)s having inherent viscosities of 0,59-1,13 dL/g were prepared by the direct polycondensation of this diimide-diacid with various aromatic diamines using triphenyl phosphite and pyridine as condensing agents in 1-methyl-2-pyrrolidone (NMP) in the presence of calcium chloride. The polymers are amorphous and readily soluble in highly polar solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, NMP, and m-cresol. Transparent and tough films can be easily cast from the polymer solutions. The glass transition temperatures of these poly(amide-imide)s are above 320°C. Thermal analyses indicated that these polymers are fairly stable, and the 10% weight loss temperatures were recorded in the range of 532–622°C in nitrogen atmosphere. 相似文献
33.
Chen Du Megan Chong Hueh Zan Min Jung Cho Jenifer I. Fenton Pao Ying Hsiao Richard Hsiao Laura Keaver Chang-Chi Lai HeeSoon Lee Mary-Jon Ludy Wan Shen Winnie Chee Siew Swee Jyothi Thrivikraman Kuo-Wei Tseng Wei-Chin Tseng Stephen Doak Sara Yi Ling Folk Robin M. Tucker 《Nutrients》2021,13(2)
Background: The coronavirus disease 2019 (COVID-19) pandemic has increased the already high levels of stress that higher education students experience. Stress influences health behaviors, including those related to dietary behaviors, alcohol, and sleep; yet the effects of stress can be mitigated by resilience. To date, past research studying the connections between dietary behaviors, alcohol misuse, sleep, and resilience commonly investigated singular relationships between two of the constructs. The aim of the current study was to explore the relationships between these constructs in a more holistic manner using mediation and moderation analyses. Methods: Higher education students from China, Ireland, Malaysia, South Korea, Taiwan, the Netherlands, and the United States were enrolled in a cross-sectional study from April to May 2020, which was during the beginning of the COVID-19 pandemic for most participants. An online survey, using validated tools, was distributed to assess perceived stress, dietary behaviors, alcohol misuse, sleep quality and duration, and resilience. Results: 2254 students completed the study. Results indicated that sleep quality mediated the relationship between perceived stress and dietary behaviors as well as the relationship between perceived stress and alcohol misuse. Further, increased resilience reduced the strength of the relationship between perceived stress and dietary behaviors but not alcohol misuse. Conclusion: Based on these results, higher education students are likely to benefit from sleep education and resilience training, especially during stressful events. 相似文献
34.
Nonhereditary p53 mutations in T-cell acute lymphoblastic leukemia are associated with the relapse phase 总被引:2,自引:0,他引:2
We have previously reported that greater than 60% of human leukemic T- cell lines possess mutations in the p53 tumor suppressor gene. To determine whether T-cell acute lymphoblastic leukemia (T-ALL) patient samples possess p53 mutations, we screened peripheral blood-and bone marrow-derived leukemia samples, taken at diagnosis and at relapse, for p53 mutations. Exons 4 through 9 and selected intron regions of the p53 gene were analyzed using polymerase chain reaction-single-strand conformation polymorphism and direct sequencing. p53 mutations were found in 0 of 15 T-ALL diagnosis samples, as compared with 10 of 36 (28%) T-ALL relapse samples. To determine whether p53 mutations play a role in the recurrence (relapse) of T-ALL, two special groups of T-ALL patients were studied: (1) a group of 8 relapse patients whose disease was refractory to chemotherapeutic treatment, and (2) a group of 6 "paired" T-ALL cell samples from patients for whom we possess both diagnosis and relapse samples. Three of 8 relapsed patients (37.5%) whose disease was refractory to the reinduction of remission by chemotherapy possessed missense mutations of the p53 gene. All 3 cases had mutations in exon 5. Among the paired samples, 3 of 6 patients harbored p53 mutations at disease recurrence, but possessed only wild- type p53 alleles at diagnosis. One case had mutation on exon 4, 1 case in exon 5, and 1 case in exon 8 with loss of heterozygosity. These data clearly indicate that recurrence of T-ALL is associated with missense mutations in p53. Our results indicate that (1) mutations of p53 do occur in T-ALL in vivo, and such mutations are associated with the relapse phase of the disease; and (2) p53 mutation is involved in the progression of T-ALL. This conclusion is supported by our observation that the introduction of T-ALL-derived mutant p53 expression constructs into T-ALL cell lines further increases their growth rate in culture, enhances cell cloning in methylcellulose, and increases tumor formation in nude mice. 相似文献
35.
Tsui-Lien Hung Fen-Fen Chen Jacqueline M Liu Wu-Wei Lai Ai-Li Hsiao Wen-Tsung Huang Helen H W Chen Wu-Chou Su 《Clinical cancer research》2003,9(7):2605-2612
PURPOSE: Lung adenocarcinoma presenting as malignant pleural effusion (MPE) is common in Taiwan. Microscopically, the involved pleurae are infiltrated by numerous tumor foci, which suggests that the cancer cells are highly invasive. Overexpression of HER-2/neu has been related to proliferation, antiapoptosis, and the high invasiveness of various cancer cells. We therefore were interested in studying the role of HER-2/neu in MPE-associated adenocarcinoma cell lung cancer (ADCLC). Experimental Design: The expression of HER-2/neu in pleural effusion was measured by ELISA. The HER-2/neu protein expression on tumor cells was evaluated by immunohistochemical (IHC) staining, and gene amplification was assayed by fluorescence in situ hybridization. RESULTS: The mean value of HER-2/neu in pleural effusions of patients with ADCLC and other nonmalignant lung diseases was 9.9 and 2.7 ng/ml, respectively. The difference is statistically significant (P < 0.001). Compared with cytokeratin 19 fragment CYFRA 21-1, the performance of HER-2/neu as a tumor marker in pleural effusion diagnosis was better. Overexpression of HER-2/neu in tumor tissues was found in 70% (23 of 32) of patients with MPE-associated ADCLC, 30% (13 of 43) with stage I/II non-small cell lung cancer (NSCLC), and 44% (14 of 32) with stage III NSCLC. The incidence of HER-2/neu overexpression in tumor tissues of patients with MPE-associated ADCLC was significantly higher than that of patients with stage I-III NSCLC without MPE. HER-2/neu gene amplification was uncommon (1.9%). The correlation between the IHC H-score in tumor samples and the pleural effusion level of HER-2/neu was significant (P < 0.01). A higher incidence of HER-2/neu expression beyond the cutoff point (5.5 ng/ml) in pleural effusions was also found in patients whose IHC H-scores were >50. CONCLUSIONS: These findings indicate that HER-2/neu is important in the pathogenesis of MPE-associated ADCLC and is a potential tumor marker for a diagnosis of pleural effusion. 相似文献
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38.
Shih-Hsuan Hsiao Peter D Constable Geoffrey W Smith Wanda M Haschek 《Toxicological sciences》2005,86(1):194-199
Fumonisin mycotoxicosis in pigs causes a decrease in mean aortic pressure, an increase in mean pulmonary arterial pressure, and increases in serum concentrations of sphinganine (3.2 microM) and sphingosine (1.4 microM). To determine a causal relationship between the hemodynamic changes and sphingolipid alterations, we examined the in vitro effects of sphinganine, sphingosine, and sphingosine-1-phosphate on porcine aortic and pulmonary arterial rings. Both sphinganine and sphingosine relaxed un-contracted and phenylephrine-contracted aortic rings at > or = 10 microM and > or = 1 microM, respectively. Sphingosine (> or = 10 microM) relaxed un-contracted and phenylephrine-contracted pulmonary arterial rings, whereas sphingosine-1-phosphate (10 microM) contracted pulmonary arterial rings. Sphingosine (3 microM) also impaired the contractile response of pulmonary artery rings to 60 mM KCl. The results suggested that the systemic hypotension caused by fumonisin is mediated, in part, by increases in serum sphinganine and sphingosine concentrations, and the pulmonary hypertension is mediated, in part, by increased sphingosine-1-phosphate concentrations. 相似文献
39.
Teh-Ying Chou Chao-Hua Chiu Ling-Hui Li Chun-Yen Hsiao Chin-Yuan Tzen Kuo-Ting Chang Yuh-Min Chen Reury-Perng Perng Shih-Feng Tsai Chun-Ming Tsai 《Clinical cancer research》2005,11(10):3750-3757
PURPOSE: Mutations in epidermal growth factor receptor (EGFR) can be used to predict the tumor response of patients receiving gefitinib for non-small cell lung cancer (NSCLC). We investigated the association between mutations in EGFR tyrosine kinase domain and tumor response and survival in gefitinib-treated NSCLC patients. EXPERIMENTAL DESIGN: EGFR mutations in exons 18 to 21 were analyzed by DNA sequencing of paraffin-embedded tumor tissues from gefitinib-treated NSCLC patients. The results were correlated with clinical variables. RESULTS: EGFR mutations were found in 61.1% (33 of 54) of cases; response rate and disease control rate were 56.8% and 68.5%, respectively. There was no significant difference in mutation rates between adenocarcinoma (29 of 43) and nonadenocarcinoma (4 of 11; P = 0.085). However, all four nonadenocarcinomas with EGFR mutations had no response to gefitinib. Presence of EGFR mutations was the only independent predictor for disease control (P = 0.003) and tumor response (P = 0.017) in multivariate analysis; positive predictive values were 87.9% and 70.8% and negative predictive values were 61.9% and 69.2%, respectively. In comparison with patients whose tumor was negative for EGFR mutations, patients with EGFR mutations had better progression-free survival (median, 7.6 versus 1.7 months; P = 0.011) and overall survival (median, 14.7 versus 4.7 months; P = 0.046). CONCLUSIONS: Mutations in EGFR tyrosine kinase correlate with treatment response and survival in gefitinib-treated NSCLC patients and can be used as a predictive and prognostic factor. Thus, analysis of EGFR tyrosine kinase mutations in lung adenocarcinoma is of clinical significance, as it can permit the customization of treatment with EGFR tyrosine kinase inhibitors. 相似文献
40.