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101.
Saif-ur-Rehman Khattak Dilnawaz Shaikh Iqbal Ahmad Khan Usmanghani Muhammad Ali Sheraz Sofia Ahmed 《AAPS PharmSciTech》2013,14(1):177-182
The effects of solvent [acetonitrile, methanol, and acetonitrile/water mixture (20:80, v/v)], buffer concentration (phosphate buffer, pH 7.5), ionic strength and commonly employed adjuvants on the photodegradation of betamethasone-17 valerate in cream and gel formulations have been studied on exposure to UV light (300–400 nm). A validated high-performance liquid chromatography method has been used to determine the parent compound and its photodegraded products. The photodegradation data in the studied solvents showed greater decomposition of the drug in solvents with a lower dielectric constant. A comparatively higher rate of photodegradation was observed in the cream formulation compared to that for the gel formulation. The kinetic treatment of the photodegradation data revealed that the degradation of the drug follows first-order kinetics and the apparent first-order rate constants for the photodegradation reactions, in the media studied, range from 1.62 to 11.30 × 10−3 min−1. The values of the rate constants decrease with increasing phosphate concentration and ionic strength which could be due to the deactivation of the excited state and radical quenching. The second-order rate constant (k′) for the phosphate ion-inhibited reactions at pH 7.5 has been found to be 5.22 × 10−2 M−1 s−1. An effective photostabilization of the drug has been achieved in cream and gel formulations with titanium dioxide (33.5–42.5%), vanillin (21.6–28.7%), and butyl hydroxytoluene (18.2–21.6%).Key words: betamethasone-17 valerate, creams and gels, kinetics, photodegradation, photostabilization 相似文献
102.
Muhammad Murtaza Hassan Ayat Yaseen Abdelaziz Ebead Gerald Audette 《Nucleosides, nucleotides & nucleic acids》2013,32(9):518-531
AbstractA synthesis of cyclobutene nucleoside analogs in which the nucleobase is tethered by a methylene group is described. The coupling of 6-chloropurine with 3-hydroxymethyl-cyclobutanone proceeds via its triflate to give both N-7 and N-9 regioisomers with relative yields corresponding to the calculated charge distribution of the 6-chloropurinyl anion. The stereoselective reduction of the N-alkylated ketones yielded quantitatively one stereoisomer in each case. The structural assignments were based on spectroscopic data and single crystal X-ray diffraction. Attempts to photoexcite the N-7 and N-9 ketones in order to promote ring-expansion did not ensue. Preliminary evidence suggests a photodecarbonylation to cyclopropanes took place. 相似文献
103.
Iqbal Ahmad Kiran Qadeer Kefi Iqbal Sofia Ahmed Muhammad Ali Sheraz Syed Abid Ali Tania Mirza Ambreen Hafeez 《AAPS PharmSciTech》2013,14(3):1101-1107
In the spectrophotometric assay of multicomponent systems involved in drug degradation studies, some minor or unknown degradation products may be present. These products may interfere in the assay and thus invalidate the results due to their absorption in the range of analytical wavelengths. This interference may be eliminated by the application of an appropriate correction procedure to obtain reliable data for kinetic treatment. The present study is based on the application of linear and non-linear irrelevant absorption corrections in the multicomponent spectrophotometric assay of riboflavin and formylmethylflavin during the photolysis and hydrolysis studies. The correction procedures take into account the interference caused by minor or unknown products and have shown considerable improvement in the assay data in terms of the molar balance. The treatment of the corrected data has led to more accurate kinetic results in degradation studies. 相似文献
104.
Muhammad Asgher Qamar Yasmeen Hafiz Muhammad Nasir Iqbal 《Saudi Journal of Biological Sciences》2013,20(4):347-352
An indigenously isolated white rot fungus, Schizophyllum commune IBL-06 was used to decolorize Solar brilliant red 80 direct dye in Kirk’s basal salts medium. In initial screening study, the maximum decolorization (84.8%) of Solar brilliant red 80 was achieved in 7 days shaking incubation period at pH 4.5 and 30 °C. Different physical and nutritional factors including pH, temperature and fungal inoculum density were statistically optimized through Completely Randomized Design (CRD), to enhance the efficiency of S. commune IBL-06 for maximum decolorization of Solar brilliant red 80 dye. The effects of inexpensive carbon and nitrogen sources were also investigated. Percent dye decolorization was determined by a reduction in optical density at the wavelength of maximum absorbance (λmax, 590 nm). Under optimum conditions, the S. commune IBL-06 completely decolorized (100%) the Solar brilliant red 80 dye using maltose and ammonium sulfate as inexpensive carbon and nitrogen sources, respectively in 3 days. S. commune IBL-06 produced the three major ligninolytic enzymes lignin peroxidase (LiP), manganase peroxidase (MnP) and lacaase (Lac) during the decolorization of Solar brilliant red 80. LiP was the major enzyme (944 U/mL) secreted by S. commune IBL-06 along with comparatively lower activities of MnP and Laccase. 相似文献
105.
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107.
David N. Juurlink Colin R. Dormuth Anjie Huang Chelsea Hellings J. Michael Paterson Colette Raymond Anita Kozyrskyj Yola Moride Erin M. Macdonald Muhammad M. Mamdani 《PloS one》2013,8(12)
Background
Recent evidence suggests that proton pump inhibitors (PPIs) might be linked with adverse cardiac events, but a causal relationship is unproven.Methods
We applied the self-matched case series method to two studies using population-based health care data from Ontario, Canada between 1996 and 2008. The first included subjects aged 66 years or older hospitalized for acute myocardial infarction within 12 weeks following initiation of PPI, while the second included subjects hospitalized for heart failure. In both studies we designated the primary risk interval as the initial 4 weeks of therapy and the control interval as the final 4 weeks. To test the specificity of our findings we examined use of histamine H2 receptor antagonists and benzodiazepines, drugs with no plausible causal link to adverse cardiac events.Results
During the 13-year study period, we identified 5550 hospital admissions for acute myocardial infarction and 6003 admissions for heart failure within 12 weeks of commencing PPI therapy. In the main analyses, we found that initiation of a PPI was associated with a higher risk of acute myocardial infarction (odds ratio 1.8; 95% confidence interval 1.7 to 1.9) and heart failure (odds ratio 1.8; 95% confidence interval 1.7 to 1.9). However, secondary analyses revealed similar risk estimates histamine H2 receptor antagonists and benzodiazepines, drugs with no known or suspected association with adverse cardiac events.Conclusion
PPIs are associated with a short-term risk of adverse cardiac events, but similar associations are seen with other drugs exhibiting no known cardiac toxicity. Collectively these observations suggest that the association between PPIs and adverse cardiac events does not represent reflect cause-and-effect. 相似文献108.
109.
Nazish Badar Uzma Bashir Aamir Muhammad Rashid Mehmood Nadia Nisar Muhammad Masroor Alam Birjees Mazhar Kazi Syed Sohail Zahoor Zaidi 《PloS one》2013,8(11)
Background
There is little information about influenza among the Pakistani population. In order to assess the trends of Influenza-like-Illness (ILI) and to monitor the predominant circulating strains of influenza viruses, a country-wide lab-based surveillance system for ILI and Severe Acute Respiratory Illness (SARI) with weekly sampling and reporting was established in 2008. This system was necessary for early detection of emerging novel influenza subtypes and timely response for influenza prevention and control.Methods
Five sentinel sites at tertiary care hospitals across Pakistan collected epidemiological data and respiratory samples from Influenza-like illness (ILI) and severe acute respiratory illness (SARI) cases from January 2008 to December 2011. Samples were typed and sub-typed by Real-Time RT-PCR assay.Results
A total of 6258 specimens were analyzed; influenza virus was detected in 1489 (24%) samples, including 1066 (72%) Influenza type A and 423 (28%) influenza type B viruses. Amongst influenza A viruses, 25 (2%) were seasonal A/H1N1, 169 (16%) were A/H3N2 and 872 (82 %) were A(H1N1)pdm09. Influenza B virus circulation was detected throughout the year along with few cases of seasonal A/H1N1 virus during late winter and spring. Influenza A/H3N2 virus circulation was mainly observed during summer months (August-October).Conclusions
The findings of this study emphasize the need for continuous and comprehensive influenza surveillance. Prospective data from multiple years is needed to predict seasonal trends for vaccine development and to further fortify pandemic preparedness. 相似文献110.
Youssif M. Ali Hany I. Kenawy Adnan Muhammad Robert B. Sim Peter W. Andrew Wilhelm J. Schwaeble 《PloS one》2013,8(12)
The complement system is an essential component of the immune response, providing a critical line of defense against different pathogens including S. pneumoniae. Complement is activated via three distinct pathways: the classical (CP), the alternative (AP) and the lectin pathway (LP). The role of Pneumolysin (PLY), a bacterial toxin released by S. pneumoniae, in triggering complement activation has been studied in vitro. Our results demonstrate that in both human and mouse sera complement was activated via the CP, initiated by direct binding of even non-specific IgM and IgG3 to PLY. Absence of CP activity in C1q−/− mouse serum completely abolished any C3 deposition. However, C1q depleted human serum strongly opsonized PLY through abundant deposition of C3 activation products, indicating that the LP may have a vital role in activating the human complement system on PLY. We identified that human L-ficolin is the critical LP recognition molecule that drives LP activation on PLY, while all of the murine LP recognition components fail to bind and activate complement on PLY. This work elucidates the detailed interactions between PLY and complement and shows for the first time a specific role of the LP in PLY-mediated complement activation in human serum. 相似文献