全文获取类型
收费全文 | 1345589篇 |
免费 | 90663篇 |
国内免费 | 2806篇 |
专业分类
耳鼻咽喉 | 18633篇 |
儿科学 | 43314篇 |
妇产科学 | 37918篇 |
基础医学 | 200511篇 |
口腔科学 | 37688篇 |
临床医学 | 113970篇 |
内科学 | 262171篇 |
皮肤病学 | 29534篇 |
神经病学 | 102756篇 |
特种医学 | 52543篇 |
外国民族医学 | 392篇 |
外科学 | 208360篇 |
综合类 | 26500篇 |
一般理论 | 357篇 |
预防医学 | 99001篇 |
眼科学 | 30965篇 |
药学 | 99210篇 |
中国医学 | 2658篇 |
肿瘤学 | 72577篇 |
出版年
2018年 | 13113篇 |
2016年 | 11123篇 |
2015年 | 12443篇 |
2014年 | 17496篇 |
2013年 | 27268篇 |
2012年 | 36440篇 |
2011年 | 39351篇 |
2010年 | 23552篇 |
2009年 | 22301篇 |
2008年 | 37705篇 |
2007年 | 40257篇 |
2006年 | 40630篇 |
2005年 | 39652篇 |
2004年 | 38262篇 |
2003年 | 36901篇 |
2002年 | 36419篇 |
2001年 | 61605篇 |
2000年 | 63685篇 |
1999年 | 53608篇 |
1998年 | 14637篇 |
1997年 | 13185篇 |
1996年 | 13391篇 |
1995年 | 12404篇 |
1994年 | 11822篇 |
1993年 | 11134篇 |
1992年 | 41713篇 |
1991年 | 41089篇 |
1990年 | 40660篇 |
1989年 | 39236篇 |
1988年 | 36343篇 |
1987年 | 35840篇 |
1986年 | 34209篇 |
1985年 | 32635篇 |
1984年 | 24305篇 |
1983年 | 20742篇 |
1982年 | 12069篇 |
1981年 | 10801篇 |
1979年 | 22904篇 |
1978年 | 16264篇 |
1977年 | 13787篇 |
1976年 | 13137篇 |
1975年 | 14705篇 |
1974年 | 17526篇 |
1973年 | 16616篇 |
1972年 | 15951篇 |
1971年 | 14977篇 |
1970年 | 14202篇 |
1969年 | 13419篇 |
1968年 | 12764篇 |
1967年 | 11624篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
42.
M. Zamparas V.C. Kapsalis G.L. Kyriakopoulos K.G. Aravossis A.E. Kanteraki A. Vantarakis I.K. Kalavrouziotis 《Sustainable Chemistry and Pharmacy》2019
At this study a multi-criteria model was developed to examine the available procedures, techniques and methods of handling infectious waste in the large healthcare unit of University Regional General Hospital of Patras, Western Greece. Particularly, this study examined the: a) current legislation and Directives issued for medical waste management at Greece and among the other EU-members, b) contribution of healthcare wastes (HCW) generation rate on social and economic parameters in selected European countries, c) available procedures, techniques, and methods upon the disposal of infectious wastes at the healthcare studied, and, d) propositions for integrated management of such hazardous wastes. Specifically, the Analytic Hierarchy Process (AHP) methodology was applied under pair wise comparison matrices in two stages: 1) the scale factors and the indicators, and 2) the criteria and their sub–criteria. The assessment of these pair wise matrices included the indicators and the sub–criteria. Subsequently, two pair wise comparison matrices, upon a) the “Fulfillment of environmental objectives” indicator and b) the “Energy consumption” sub criterion, were denoted. The AHP methodology yielded good results; however there is still space of improving the environmental performance. The normalized relative weights obtained for the criteria and sub criteria motivated specific actions that have to be handled. Particularly, the results indicated a very good value in environmental management criteria due the values obtained for the commitment towards the environmental policy standards and the waste management procedures. However, further improvements on staff awareness (such as development programs to enhance sensitivity) and more green purchasing suppliers, should be further addressed. 相似文献
43.
44.
45.
Y. Ermias I.A. Morgan K.M. Curtis M.K. Whiteman L.G. Horton L.B. Zapata 《Contraception》2019,99(5):300-305
ObjectiveIdentify factors associated with healthcare providers' frequency of depot medroxyprogesterone acetate (DMPA) provision to adolescents.Study designWe analyzed data from surveys mailed to a nationally representative sample of public-sector providers and office-based physicians (n=1984). We estimated adjusted odds ratios (aORs) and 95% confidence intervals (CIs) of factors associated with frequent DMPA provision to adolescents in the past year.ResultsAlthough most providers (>95%) considered DMPA safe for adolescents, fewer reported frequent provision (89% of public-sector providers; 64% of office-based physicians). Among public-sector providers, factors associated with lower odds of frequent provision included working in settings without Title X funding (aOR 0.44, 95% CI 0.30–0.64), reporting primary care as their primary clinical focus versus reproductive or adolescent health (aOR 0.42, 95% CI 0.28–0.61), and providing fewer patients with family planning services. Among office-based physicians, factors associated with lower odds of frequent provision included specializing in obstetrics/gynecology (aOR 0.50, 95% CI 0.27–0.91) and family medicine (aOR 0.21, 95% CI 0.09–0.47) versus adolescent medicine, completing training ≥15 versus <5 years ago (aOR 0.27, 95% CI 0.09–0.83), and reporting that 0–24% of patients pay with Medicaid or other government healthcare assistance versus ≥50% (aOR 0.23, 95% CI 0.09–0.61). The reason most commonly reported by providers for infrequent DMPA provision was patient preference for another method.ConclusionsWhile most providers reported frequently providing DMPA to adolescents, training on evidence-based recommendations for contraception, focused on subgroups of providers with lower odds of frequent DMPA provision, may increase adolescents' access to contraception.ImplicationsAlthough >95% of providers considered depot medroxyprogesterone (DMPA) a safe contraceptive for adolescents, only 89% of public-sector providers and 64% of office-based physicians reported frequently providing DMPA to adolescents. Provider training on evidence-based recommendations for contraception counseling and provision may increase adolescents' access to DMPA and all methods of contraception. 相似文献
46.
B. Siska I. Machac P. Dolecek J. Martiska 《Pharmaceutical development and technology》2019,24(1):80-88
Rheological behaviour of pharmaceutical semisolid preparations significantly affects manufacturing process, administration, stability, homogeneity of incorporated drug, accuracy of dosing, adhesion in the place of application, drug release, and resulting therapeutic effect of the product. We performed test of consistency by penetrometry, rotational, oscillation and creep tests, and squeeze and tack tests of model samples to introduce methods suitable for characterization and comparison of semisolids in practice. Penetrometry is a simple method allowing sorting the semisolids to low and high stress-resistant materials but deficient for rheological characterization of semisolids. Value of yield stress, generally considered to be appropriate feature of semisolids, is significantly influenced by the method of testing and the way of evaluation. The hysteresis loops of model semisolids revealed incomplete thixotropy, therefore, three-step thixotropy test was employed. Semisolids showed nonlinear response in the creep phase of tests and partial recovery of structure by storing energy in the recovery phase. Squeeze and tack tests seem to be convenient ways for comparison of semisolids. Our study can contribute to a better understanding of different flow behaviour of semisolids given by different physicochemical properties of excipients and can bring useful approaches to evaluation and comparison of semisolids in practice. 相似文献
47.
48.
49.
Sandrine F. Chebekoue 《Journal of occupational and environmental hygiene》2019,16(4):308-319
This study aimed at deriving occupational thresholds of toxicological concern for inhalation exposure to systemically-acting organic chemicals using predicted internal doses. The latter were also used to evaluate the quantitative relationship between occupational exposure limit and internal dose. Three internal dose measures were identified for investigation: (i) the daily area under the venous blood concentration vs. time curve, (ii) the daily rate of the amount of parent chemical metabolized, and (iii) the maximum venous blood concentration at the end of an 8-hr work shift. A dataset of 276 organic chemicals with 8-hr threshold limit values-time-weighted average was compiled along with their molecular structure and Cramer classes (Class I: low toxicity, Class II: intermediate toxicity, Class III: suggestive of significant toxicity). Using a human physiologically-based pharmacokinetic model, the three identified dose metrics were predicted for an 8-hr occupational inhalation exposure to the threshold limit value for each chemical. Distributional analyses of the predicted dose metrics were performed to identify the percentile values corresponding to the occupational thresholds of toxicological concern. Also, simple linear regression analyses were performed to evaluate the relationship between the 8-hr threshold limit value and each of the predicted dose metrics, respectively. No threshold of toxicological concern could be derived for class II due to few chemicals. Based on the daily rate of the amount of parent chemical metabolized, the proposed internal dose-based occupational thresholds of toxicological concern were 5.61?×?10?2 and 9?×?10?4 mmol/d at the 10th percentile level for classes I and III, respectively, while they were 4.55?×?10?1 and 8.5?×?10?3 mmol/d at the 25th percentile level. Even though high and significant correlations were observed between the 8-hr threshold limit values and the predicted dose metrics, the one with the rate of the amount of chemical metabolized was remarkable regardless of the Cramer class (r2 = 0.81; n = 276). The proposed internal dose-based occupational thresholds of toxicological concern are potentially useful for screening-level assessments as well as prioritization within an integrated occupational risk assessment framework. 相似文献
50.