全文获取类型
收费全文 | 186107篇 |
免费 | 1820篇 |
国内免费 | 69篇 |
专业分类
耳鼻咽喉 | 1341篇 |
儿科学 | 6967篇 |
妇产科学 | 3251篇 |
基础医学 | 17779篇 |
口腔科学 | 1758篇 |
临床医学 | 13421篇 |
内科学 | 32488篇 |
皮肤病学 | 882篇 |
神经病学 | 17680篇 |
特种医学 | 9449篇 |
外科学 | 30302篇 |
综合类 | 2517篇 |
一般理论 | 8篇 |
预防医学 | 19189篇 |
眼科学 | 3305篇 |
药学 | 10100篇 |
1篇 | |
中国医学 | 624篇 |
肿瘤学 | 16934篇 |
出版年
2022年 | 114篇 |
2021年 | 250篇 |
2020年 | 115篇 |
2019年 | 210篇 |
2018年 | 22118篇 |
2017年 | 17491篇 |
2016年 | 19638篇 |
2015年 | 1066篇 |
2014年 | 1073篇 |
2013年 | 1182篇 |
2012年 | 7493篇 |
2011年 | 21543篇 |
2010年 | 19136篇 |
2009年 | 11829篇 |
2008年 | 19973篇 |
2007年 | 22163篇 |
2006年 | 1006篇 |
2005年 | 2627篇 |
2004年 | 3855篇 |
2003年 | 4766篇 |
2002年 | 2867篇 |
2001年 | 589篇 |
2000年 | 706篇 |
1999年 | 476篇 |
1998年 | 289篇 |
1997年 | 302篇 |
1996年 | 173篇 |
1995年 | 199篇 |
1994年 | 195篇 |
1993年 | 139篇 |
1992年 | 237篇 |
1991年 | 284篇 |
1990年 | 330篇 |
1989年 | 240篇 |
1988年 | 217篇 |
1987年 | 231篇 |
1986年 | 195篇 |
1985年 | 229篇 |
1984年 | 144篇 |
1983年 | 123篇 |
1982年 | 107篇 |
1980年 | 119篇 |
1979年 | 118篇 |
1978年 | 121篇 |
1977年 | 88篇 |
1976年 | 93篇 |
1974年 | 117篇 |
1973年 | 100篇 |
1970年 | 107篇 |
1969年 | 91篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Scarlett Lin Gomez Cynthia D O'Malley Antoinette Stroup Sarah J Shema William A Satariano 《BMC cancer》2007,7(1):193
Background
Colorectal cancer, if detected early, has greater than 90% 5-year survival. However, survival has been shown to vary across racial/ethnic groups in the United States, despite the availability of early detection methods. 相似文献62.
Carmen Guillén Ponce María Pilar Garrido López María José Molina Garrido Gema Muñoz Molina Alfredo Carrato 《Clinical & translational oncology》2007,9(1):53-55
Pituitary metastases of solid tumours are infrequent, specially as a first manifestation. When they happen, they are usually
due to breast or lung cancer and are asymptomatic or produce diabetes insipidus. It is very strange that they produce hormonal
deficiency.
We present a case report of a bronchogenic adenocarcinoma in a 65-year-old man which began with panhypopituitarism, diabetes
insipidus and visual alterations. Magnetic resonance imaging revealed a large sellar mass, with clivus infiltration and invading
the right cavernous sinus. The biopsy result was adenocarcinoma metastases from lung cancer. 相似文献
63.
Ricardo J. Wray Jo Ellen Stryker Eric Winer George Demetri Karen M. Emmons 《Journal of cancer education》2007,22(1):21-24
Background. Accepted practices of informed consent often result in suboptimal patient understanding of research studies.Methods. This pilot study aimed to assess trial-specific tailored materials, compared to a widely used generic booklet about clinical
trials, randomly assigned to 118 candidates for cancer clinical trials. Study outcomes were: satisfaction with decision-making;
satisfaction with materials; and subjective understanding of the clinical trial.Results. There were no major differences between groups. Participants rated tailored materials higher as a useful reference.Conclusions. Trial-specific materials hold utility for reference during clinical trials. Studies of informed consent are feasible, although
important factors limit research. 相似文献
64.
Compared with results obtained in locally anesthetized, paralyzed rats, the dissociative anesthetic ketamine did not alter either the number of spontaneously active striatal neurons or the basal firing rate of striatal neurons; 90% of these cells exhibited the type I striatal neuron waveform. Chloral hydrate anesthesia suppressed both the occurrence and the firing rate of spontaneously active type I cells, but did not alter the activity of type II striatal neurons. Cortical stimulation preferentially activated type II cells in paralyzed rats and in chloral hydrate-anesthetized rats. Thus, under dissociative anesthesia it is possible to study spontaneously active type I striatal neurons. However, a method of activation such as cortical stimulation is necessary to study type II striatal neurons. 相似文献
65.
Ramona A. Cole Anita Bansal Debra M. Moriarity William A. Haber William N. Setzer 《Journal of natural medicines》2007,61(4):414-417
The leaf essential oil of Eugenia zuchowskiae from Monteverde, Costa Rica, has been obtained by hydrodistillation and analyzed by GC–MS. The principal constituents of
E. zuchowskiae leaf oil were α-pinene (28.3%), β-caryophyllene (13.2%), α-humulene (13.1%), and α-copaene (8.1%). The leaf essential oil
of E. zuchowskiae showed pronounced in-vitro cytotoxic activity against MCF-7, MDA-MB-468, and UACC-257 human tumor cell lines. The major components
showed cytotoxic activities comparable to doxorubicin (LC50 14–70 μg/ml). 相似文献
66.
American Diabetes Association The initial draft of this paper was prepared by Rebecca G. Schafer MS RD ; Betsy Bohannon MS RD; Marion J. Franz MS RD; Janine Freeman RD; Alberta Holmes MS RD; Sue McLaughlin RD; Linda B. Haas RN; Davida F. Kruger MSN RN; Rodney A. Lorenz MD; Molly M.McMahon MD 《Journal of the American Dietetic Association》1997,97(1):52-53
67.
68.
Williams C. A. Jones H. D. Freeman R. W. Wernke M. J. Williams P. L. Roberts S. M. James R. C. 《Regulatory toxicology and pharmacology : RTP》1994,20(3)
Reference doses (RfDs) and reference concentrations (RfCs) developed by the United States Environmental Protection Agency (USEPA) are typically used in the quantitation of risk of potential adverse human health effects from exposure to environmental chemicals. For a large number of chemicals, however, USEPA RfDs and RfCs have not yet been determined. Thus, for risk assessments that involve a large number of chemicals, there is insufficient toxicity information with which to evaluate potential adverse human health effects for all chemicals present at a particular site. Due to this insufficiency, the risk assessor must either (1) ignore potential exposures on the assumption that omitting these exposures does not significantly alter decisions concerning the remediation of the site or (2) undertake a lengthy and costly analysis to generate the necessary RfDs or RfCs. A potential solution to this problem is to develop estimated permissible concentrations (EPCs), values which represent permissible environmental concentrations or related acceptable daily dosages derived from occupational exposure limits. In the present analysis, acceptable daily dosages determined using the EPC method were compared to USEPA RfDs or RfCs which were converted to dosages based on standard exposure assumptions. Based on a comparative analysis of EPCs and USEPA reference values for 103 chemicals, it was found that EPC daily dosages represent a reasonably conservative surrogate value when USEPA or state reference values are unavailable. Given that there are hundreds of chemicals with occupational exposure limits but no state or USEPA reference values, acceptance of the EPC methodology would provide an interim solution for the problem of insufficient toxicity information for a substantial number of environmental chemical contaminants. 相似文献
69.
70.