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71.
利用流态化化学气相淀积(CVD)制备Al_2O_3-SnO_2复合粒子。探讨了SnO_2在Al_2O_3超细颗粒上的包敷状态,考察了反应温度、反应物进料浓度比、反应时间等对反应结果的影响。结果表明,SnO_2在复合粒子团聚体体相中呈均匀分布,形成Al_2O_3-SnO_2复合粒子,SnO_2均匀淀积在Al_2O_3超细颗粒原生粒子表面,流态化CVD包敷效果优于非流化过程;随反应时间的延长,产物中SnO_2含量线性递增;而当反应温度高于300℃,反应物H_2O和SnCl_4配比大于4:1时,SnO_2含量基本保持不变。 相似文献
72.
研究目的探讨苯酞类天然产物的合成方法及其生物活性。研究方法以邻苯二甲酐为底物,首先引入丁烯基,再进行烯丙位氧化,制得目标化合物。结果通过丁基锂反应,得到了具有药物活性的丁烯基苯酞,然后利用SeO2烯丙位氧化,首次合成了Z-3-(2-羟基丁烯基)苯酞。结论此合成方法原料易得,方法简便,为苯酞类化合物的合成研究提供了一个新的途径。 相似文献
73.
74.
Cardiovascular malformations, work attendance, and occupational exposures during pregnancy in Finland 总被引:1,自引:0,他引:1
J Tikkanen K Kurppa H Timonen P C Holmberg E Kuosma K Rantala 《American journal of industrial medicine》1988,14(2):197-204
To explore for associations between occupational factors and cardiovascular malformations, information on the parents of 160 infants with cardiovascular malformations and 160 control parents was studied. The case infants had been reported consecutively to the Finnish Register of Congenital Malformations. All mothers were interviewed identically after delivery, using both open and pro forma questions about detailed work tasks, exposures, and leisure activities during pregnancy. The interview information was evaluated blindly. Neither parental occupational titles nor maternal working per se gave new clues to the teratogenic risk; nor did shift working, wearing of personal protective equipment, or the mother's own opinion on exposures during pregnancy. Identified occupational exposures, as categorized by an industrial hygienist, showed no remarkable associations to cardiovascular malformations. Few mothers were exposed substantially to specific occupational hazards. Comparing mothers who used medications in the first trimester with those who did not showed an odds ratio of 2.2 (95% confidence interval 1.3-3.9) when adjusted for potential confounding by multivariate logistic methods. 相似文献
75.
羧基化多壁碳纳米管修饰电极伏安法测定多巴胺 总被引:7,自引:2,他引:5
目的 :研究用羧基化多壁碳纳米管修饰电极伏安法测定痕量多巴胺 (DA)的效果。方法 :采用涂布法制成羧基化多壁碳纳米管修饰电极 ;在pH =5 .4的KH2 PO4 Na2 HPO4缓冲溶液中 ,采用该修饰电极伏安法测定DA。结果 :该修饰电极对DA有着显著的电催化作用 ,与裸玻碳电极相比较 ,其灵敏度大大提高 ,在2 .0× 10 -7~ 6 .0× 10 -4mol/L浓度范围内 ,DA的氧化峰电流与浓度成良好的线性关系 ,检测限为 5 .0× 10 -8mol/L。将该修饰电极用于盐酸多巴胺针剂的测定 ,相对平均偏差为 1.4 % ,平均回收率为 99.2 %。结论 :该修饰电极响应快 ,灵敏度高 ,稳定性好 ,寿命长 ,适合于具有电活性生物分子的测定 相似文献
76.
In spite of significant efforts in academic and commercial laboratories, major breakthroughs in oral peptide and protein formulation have not been achieved. The major barriers to developing oral formulations for peptides and proteins include poor intrinsic permeability, lumenal and cellular enzymatic degradation, rapid clearance, and chemical and conformational stability. Pharmaceutical approaches to address these barriers, which have been successful with traditional, small, organic drug molecules, have not readily translated into effective peptide and protein formulations. The success achieved by Sandoz with cyclosporin formulations remains one clear example of what can be achieved, although it is likely that effective oral formulations for peptides and proteins will remain highly compound specific. Although the challenges are significant, the potential therapeutic benefit remains high, particularly with the increasing identification of potential peptide and protein drug candidates emerging from the biotechnology arena. Successful formulations will most likely require a systematic and careful merger of formulation and design delivery systems which maximize the potential for absorption across the epithelial cell layer. 相似文献
77.
本文定义了一类“近乎双线性”系统。可用以近似一类奇异摄动双线性系统,而且可以描述某些实际工业对象。并发现其控制器的设计较方便。文中还给出了一种简单的反馈控制器的设计方法。又对一类多输入双线性系统,提出一种设计反馈控制器的改进方案,根据Lyapunov定理得到一非线性反馈控制律。以上设计方法分别对某合成氨反应器作了应用研究,仿真结果表明了方法的有效性。 相似文献
78.
Tryptamine (TA) occurs in trace levels in the brain, but its role in the central nervous system is not clear. However, there is evidence that TA may be a neuromodulator since it binds to specific binding sites in the brain. TA was measured as a diheptafluorobutyryl derivative in rat whole brain by capillary gas chromatography—mass spectrometry using negative chemical ionization (NCI) and single ion monitoring (SIM). d4-TA was used as the internal standard. The ions m/z 532 and m/z 536 were monitored to identify TA and d4-TA, respectively and to calculate the concentration of TA in rat whole brain which was found to be 0.19 ± 0.08 ng g−1 (n = 8). The results confirm the earlier TA concentrations measured by GC—MS using positive electron impact ionization. However, NCI improved the signal/noise ratio of the method increasing its sensitivity for TA. 相似文献
79.
Berner Bret Wilson Donald R. Guy Richard H. Mazzenga Gerard C. Clarke Frank H. Maibach Howard I. 《Pharmaceutical research》1988,5(10):660-663
The relationship between pK
a and skin irritation in man is studied for a homologous series of benzoic acid derivatives, which permeate through human skin at comparable rates (15–88 µg/cm2/hr). Skin irritation and pK
a are correlated for pK
a 4. Laser Doppler velocimetric assessment of skin blood flow, color meter readings, erythema, edema, and the primary irritation index are all linearly correlated and related to pK
a, erythema at 24 hr appears to be the most sensitive parameter to variation in pK
a when pK
a 4. 相似文献
80.
目的探讨装潢居室空气中挥发性化合物的遗传毒性.方法采用小鼠骨髓嗜多染性红细胞微核试验和小鼠精子畸形试验检测居室装潢后空气中挥发性化合物的遗传毒性.结果该化合物对小鼠呼吸系统有明显的刺激作用,与阴性对照组比较,高、中、低剂量组的微核率、精子畸形率均有显著差异性.结论居室装潢后室内空气中挥发性化合物具有遗传毒性作用. 相似文献