全文获取类型
收费全文 | 20106篇 |
免费 | 1888篇 |
国内免费 | 330篇 |
专业分类
耳鼻咽喉 | 105篇 |
儿科学 | 558篇 |
妇产科学 | 267篇 |
基础医学 | 1201篇 |
口腔科学 | 361篇 |
临床医学 | 3734篇 |
内科学 | 2398篇 |
皮肤病学 | 152篇 |
神经病学 | 1088篇 |
特种医学 | 1224篇 |
外科学 | 1279篇 |
综合类 | 2862篇 |
现状与发展 | 1篇 |
一般理论 | 1篇 |
预防医学 | 4254篇 |
眼科学 | 282篇 |
药学 | 1187篇 |
64篇 | |
中国医学 | 541篇 |
肿瘤学 | 765篇 |
出版年
2024年 | 88篇 |
2023年 | 447篇 |
2022年 | 810篇 |
2021年 | 1059篇 |
2020年 | 968篇 |
2019年 | 906篇 |
2018年 | 861篇 |
2017年 | 897篇 |
2016年 | 789篇 |
2015年 | 785篇 |
2014年 | 1424篇 |
2013年 | 1887篇 |
2012年 | 1158篇 |
2011年 | 1213篇 |
2010年 | 973篇 |
2009年 | 915篇 |
2008年 | 944篇 |
2007年 | 889篇 |
2006年 | 750篇 |
2005年 | 625篇 |
2004年 | 501篇 |
2003年 | 451篇 |
2002年 | 396篇 |
2001年 | 307篇 |
2000年 | 245篇 |
1999年 | 253篇 |
1998年 | 197篇 |
1997年 | 204篇 |
1996年 | 172篇 |
1995年 | 139篇 |
1994年 | 139篇 |
1993年 | 122篇 |
1992年 | 107篇 |
1991年 | 88篇 |
1990年 | 69篇 |
1989年 | 61篇 |
1988年 | 67篇 |
1987年 | 56篇 |
1986年 | 45篇 |
1985年 | 48篇 |
1984年 | 31篇 |
1983年 | 29篇 |
1982年 | 36篇 |
1981年 | 30篇 |
1980年 | 33篇 |
1979年 | 26篇 |
1978年 | 19篇 |
1977年 | 21篇 |
1976年 | 15篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
72.
目的:探寻丹参酮提取物化学成分的含量与物理性质之间的相关性。方法:HPLC测定50批丹参酮提取物中隐丹参酮、丹参酮IIA的含量,经典方法测定物理性质,将成分含量与物理性质进行相关性分析。结果:两变量组组内的隐丹参酮与丹参酮IIA含量,D10、D50、D90 之间,松装密度与振实密度,豪斯纳比率与压缩度指数均具有较强的相关性,休止角与均齐度、豪斯纳比率、压缩度指数具有一定的相关性,但相关性不强。两变量组的原始变量组间相关性系数最大不超过0.400,相关性不强。经过典型相关分析,3对典型变量的相关性显著,相关系数分别为0.851,0.674,0.565。结论:对于丹参酮提取物的化学、物理质量属性,原始变量组内具有较好的相关性,但组间相关性较差。相比原始变量,典型变量呈现出了较好的组间相关性,表明丹参酮提取物的物理化学属性之间具有一定的相关性。 相似文献
73.
The objective of this study was to explore the effect of COVID-19 and Ramadan on physical activity (PA) and burnout in teachers and the relationship between them. A total of 57 secondary school teachers from public education centers participated in the present study. They were aged between 29 and 52 years. To determine the effect of Ramadan and COVID-19 on PA and burnout, participants completed the online questionnaires before COVID-19, one week before Ramadan and during the second week of Ramadan. The International Physical Activity Questionnaire-BREF and the Maslach Burnout Inventory-Human Services Survey were used to assess PA intensities and burnout, respectively. The data revealed that total PA (p < 0.001, p < 0.05, respectively) vigorous metabolic equivalent of task (MET) (p < 0.001, p < 0.05, respectively), moderate MET (p < 0.001, p < 0.01, respectively) were higher before COVID-19 and before Ramadan than during Ramadan. Regarding burnout subscales, emotional exhaustion (p < 0.001, p < 0.01, respectively) was higher before Ramadan than before COVID-19 and during Ramadan. A lower personal accomplishment was reported before Ramadan than before COVID-19 and during Ramadan (both p < 0.05). In addition, low to high correlations were observed between PA intensities and burnout subscales, except for the correlation between depersonalization and all PA intensities. In conclusion, Ramadan intermittent fasting along with PA was highly recommended for teachers and the general population to improve positive emotions and general health. 相似文献
74.
用自制原料制备了前列地尔静注乳剂,并对其一些物理性质进行了测定,结果表明该制剂的粒度分布、pH值、渗透压等项均符合静脉注射制剂的要求. 相似文献
75.
76.
Nehal Elkhoshkhany Samir Marzouk Mohammed El-Sherbiny Heba Ibrahim Bozena Burtan-Gwizdala Mohammed S. Alqahtani Khalid I. Hussien Manuela Reben El Sayed Yousef 《Materials》2022,15(15)
A novel series of glass, consisting of B2O3, Bi2O3, TeO2, and TiO2 (BBTT) containing rare earth oxide RE2O3, where RE is La, Ce, Sm, Er, and Yb, was prepared. We investigated the structural, optical, and gamma attenuation properties of the resultant glass. The optical energy bands, the linear refractive indices, the molar refractions, the metallization criteria, and the optical basicity were all determined for the prepared glass. Furthermore, physical parameters such as the density, the molar volume, the oxygen molar volume, and the oxygen packing density of the prepared glass, were computed. Both the values of density and optical energy of the prepared glass increased in the order of La2O3, Ce2O3, Sm2O3, Er2O3, and then Yb2O3. In addition, the glass doped with Yb2O3 had the lowest refractive index, electronic polarizability, and optical basicity values compared with the other prepared glass. The structures of the prepared glass were investigated by the deconvolution of infrared spectroscopy, which determined that TeO4, TeO3, BO4, BO3, BiO6, and TiO4 units had formed. Furthermore, the structural changes in glass are related to the ratio of the intensity of TeO4/TeO3, depending on the type of rare earth. It is also clarified that the resultant glass samples are good attenuators against low-energy radiation, especially those that modified by Yb2O3, which exhibited superior shielding efficiency at energies of 622, 1170, and 1330 keV. The optical and gamma ray spectroscopy results of the prepared glass show that it is a good candidate for nonlinear optical fibers, laser solid material, and optical shielding protection. 相似文献
77.
Background: Obesity relates to impaired olfactory function. Abnormal olfactory function is also associated with poor diet; however, whether obesity-related markers shape this relationship is unknown. Methods: Cross-sectional analysis (n = 1415, age > 40 years) of NHANES 2013–2014 examined body fat percent (BF%) and waist circumference (WC) as moderators of the relationship between olfactory function and diet. The olfactory function test identified adults with olfactory dysfunction (OD) or normal olfaction (NO). Validated 24 h recall captured nutrient intake and Healthy Eating Index-2010 scores. BF% and WC were measured. We tested adjusted linear regression models, with an interaction term between olfactory function and BF%/WC, for each nutrient or HEI score, and reported coefficients (β), standard errors (SE), and p-values for significant interaction terms. Results: In OD (9.5%; mean age 50.9 years, 95% CI 49.6, 52.2) compared with NO (mean age 49.3 years, 95% CI 48.8, 49.9), higher BF% was associated with higher intake of saturated fat (β (SE): 0.2 (0.1) g; p = 0.06) and percent of total calories from total fat (0.2 (0.1); p = 0.07), saturated (0.1 (0.004); p = 0.02), and monounsaturated fat (0.1 (0.1); p = 0.08); lower percent of total calories from carbohydrates (−0.2 (0.1); p = 0.09) and mg of sodium (−17.8 (09.6); p = 0.08); and a higher (healthier) refined grain score (0.1 (0.1); p = 0.04). Higher WC was associated with higher refined grain scores (0.01 (0.02); p = 0.01) in OD. Conclusion: BF% may shape dietary intake and quality in OD. Longitudinal studies are needed to elucidate the directionality of these relationships and develop strategies to improve dietary intake among OD. 相似文献
78.
目的:探讨无创正压通气(NPPV)联合镇静剂和(或)纤维支气管镜〔纤支镜)吸痰治疗肺心病并肺性脑病患者的疗效和安全性。方法:实验组22例,男13例,女9例,平均年龄(71.2±4.7)岁,肺心病并肺性脑病患者在常规治疗的基础上,应用NPPV联合纤支镜检查行深部痰细菌培养和清除分泌物,并依据病情必要时予镇静剂。对照组为同期达到同样标准的患者25例,男16例,女9例,平均年龄(70.6±5.3)岁。结果:实验组患者均能进行NPPV治疗,通气前后PaCO2,分别为(11.03±2.12)kPa和(7.65±1.69)kPa,PaO2,为(7.82±1.88)kPa和(11.15±2.08)kPa,有显著改善(P<0.01);实验组患者均行纤支镜吸痰并全部取得了合格的深部痰标本,操作过程无并发症;与对照组比较,实验组的痰菌阳性率(73.9%与32%)、插管率(30.4%与60.0%)、病死率(21.7%与52.0%)、住院天数(21.6±7.2)d与(34.3±12.3)d均有显著差异(P<0.01)。实验组有10例患者接受镇静剂治疗。结论:NPPV联合镇静剂和(或)纤支镜吸痰治疗老年肺心病并肺性脑病患者的效果良好;应用镇静剂时,应做好机械通气的准备。 相似文献
79.
Tadayoshi Nonoyama Hiroko Shigemi Masafumi Kubota Akihiko Matsumine Kenji Shigemi Tamotsu Ishizuka 《Medicine》2022,101(31)
Critically ill patients in the intensive care unit (ICU) develop muscle atrophy and decreased physical function. Though neuromuscular electrical stimulation (NMES) therapy has been shown to be effective in preventing this, but its effect on older patients is unknown.To examine the course of critically ill older patients treated with NMES in the ICU and to define the impact of its use.A retrospective cohort study was conducted using older ICU patients (≥65 years) categorized into a control group (n = 20) and an NMES group (n = 22). For subgroup analysis, each group was further classified into pre-old age (65–74 years) and old age (≥75 years).The control group showed significant decrease in muscle thickness during ICU and hospital stay. The NMES group showed lower reduction in muscle thickness and showed decrease in muscle echo intensity during hospital stay, compared to the control group. NMES inhibited decrease in muscle thickness in the pre-old age group versus the old age group. The decreasing effect of NMES on echo intensity during hospital stay manifested only in the pre-old age group. We did not find much difference in physical functioning between the NMES and control groups.Lower limb muscle atrophy reduces in critically ill older patients (≥65 years) with NMES and is pronounced in patients aged < 75 years. The impact of NMES on the physical functioning of older patients in ICU needs to be further investigated. 相似文献
80.