全文获取类型
收费全文 | 16614篇 |
免费 | 951篇 |
国内免费 | 26篇 |
专业分类
耳鼻咽喉 | 219篇 |
儿科学 | 414篇 |
妇产科学 | 201篇 |
基础医学 | 2062篇 |
口腔科学 | 607篇 |
临床医学 | 1471篇 |
内科学 | 3190篇 |
皮肤病学 | 333篇 |
神经病学 | 1805篇 |
特种医学 | 1184篇 |
外国民族医学 | 1篇 |
外科学 | 2455篇 |
综合类 | 153篇 |
一般理论 | 4篇 |
预防医学 | 1500篇 |
眼科学 | 318篇 |
药学 | 807篇 |
中国医学 | 14篇 |
肿瘤学 | 853篇 |
出版年
2021年 | 202篇 |
2020年 | 125篇 |
2019年 | 154篇 |
2018年 | 238篇 |
2017年 | 191篇 |
2016年 | 217篇 |
2015年 | 273篇 |
2014年 | 387篇 |
2013年 | 506篇 |
2012年 | 704篇 |
2011年 | 753篇 |
2010年 | 490篇 |
2009年 | 415篇 |
2008年 | 746篇 |
2007年 | 818篇 |
2006年 | 750篇 |
2005年 | 746篇 |
2004年 | 672篇 |
2003年 | 648篇 |
2002年 | 651篇 |
2001年 | 635篇 |
2000年 | 588篇 |
1999年 | 478篇 |
1998年 | 190篇 |
1997年 | 133篇 |
1996年 | 117篇 |
1995年 | 156篇 |
1994年 | 128篇 |
1992年 | 334篇 |
1991年 | 361篇 |
1990年 | 304篇 |
1989年 | 284篇 |
1988年 | 265篇 |
1987年 | 228篇 |
1986年 | 253篇 |
1985年 | 254篇 |
1984年 | 200篇 |
1983年 | 182篇 |
1982年 | 122篇 |
1981年 | 121篇 |
1980年 | 115篇 |
1979年 | 238篇 |
1978年 | 153篇 |
1977年 | 147篇 |
1975年 | 147篇 |
1974年 | 127篇 |
1973年 | 135篇 |
1972年 | 142篇 |
1971年 | 110篇 |
1970年 | 117篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
The postoperative patient may present with one or more of a variety of problems amenable to management by interventional radiologic techniques, which may be curative by themselves or may, in addition, require or allow successful surgical intervention. To optimize patient care, a good working relationship between the vascular surgeon and the interventional radiologist is essential. Consideration should be given to the patient's presenting signs and symptoms, the surgical history with its alteration of anatomy, the results of available noninvasive studies, and knowledge of various therapeutic alternatives. Vascular radiologic interventions include angioplasty, thrombolytic therapy, a combination of both angioplasty and thrombolysis, and newer techniques such as percutaneous valvectomy. In this report, examples of some of the experience at Indiana University are presented. Emphasis is placed on the appropriate approach to the patient. 相似文献
52.
53.
54.
B D Hardin R A Becker R J Kavlock J M Seidenberg N Chernoff 《Teratogenesis, carcinogenesis, and mutagenesis》1987,7(1):119-127
The Chernoff/Kavlock assay, proposed as a preliminary screen for teratogenic potential, was the subject of a 2-day workshop sponsored by the National Institute for Occupational Safety and Health. Data from three large testing programs were presented, representing tests of 165 chemicals, of which 33 were tested at least twice. Applications of the test in industrial laboratories and product development, hazard identification, and risk assessment were discussed. Workshop participants recognized the assay as one of several valid ways to preliminarily evaluate chemicals with unknown developmental toxicity. Other preliminary tests were also discussed in terms of their relationship to this test, which was seen as having the advantage of providing information on neonatal viability. Other techniques, particularly an abbreviated conventional teratology study, were also recognized as appropriate screens. The preferred test in a particular laboratory will be dependent upon the particular skills and objectives of that laboratory. Standardized protocols were suggested, but flexibility in experimental design was considered necessary, and many variations on the basic test could be appropriate. This preliminary test has been used most often as a single-dose test in mice, but might provide more generally useful data if conducted in rats using two dose levels. Workshop participants viewed the test as highly reliable in correctly identifying developmentally toxic chemicals and suggested that a negative finding in a properly conducted Chernoff/Kavlock test could be a sufficient basis for regulatory agencies to determine that conventional teratology tests in the same species are not warranted. 相似文献
55.
Platelet aggregability is known to be enhanced and platelet-survival time shortened in smokers when compared with nonsmokers. Up to now it is unknown which of the substances in tobacco smoke are responsible for these effects. To evaluate a possible role of nicotine, rats were chronically treated with the alkaloid (10 mg/kg/day), continuously released from subcutaneously implanted osmotic minipumps. Surprisingly, after 8 weeks, platelet sensitivity toward the aggregating stimulus adenosine 5'-diphosphate (ADP) was markedly reduced. The mean ADP concentration required to induce half the maximum rate of aggregation (EC50) was 0.88 mumol/L in nicotine-treated animals, as compared with 0.67 mumol/L in controls (p less than 0.002). Platelet aggregability remained normal when the rats were treated simultaneously with nicotine and the beta blocker propranolol (3.5 mg/kg/day); for these animals, the mean EC50 for ADP was 0.73 mumol/L. These results are suggestive of a catecholamine-mediated action of nicotine. However, neither the basal levels of cAMP in platelet-rich plasma, nor the cAMP levels attained after stimulation of platelet adenylate cyclase with prostaglandin E1 (PGE1), were affected by 8 weeks of treatment with nicotine or nicotine plus propranolol. No effect on platelet aggregation was observed when the rats were treated with nicotine for only 2 weeks, or when nicotine or nicotine plus cotinine were added to platelet-rich plasma in vitro in concentrations equal to those attained in vivo after 8 weeks. Thus, prolonged application of nicotine in vivo caused an inhibition of ADP-induced rat platelet aggregation presumably mediated by beta-catecholaminergic stimulation of platelets.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
56.
57.
58.
PURPOSE: New federal regulations allow for office-based treatment of opioid dependent patients with opioid agonist medication (e.g., buprenorphine). We sought to evaluate the literature on office-based physicians' acceptance of this practice. METHODS: We searched the MEDLINE database for original research examining office-based providers' acceptance or satisfaction with office-based treatment. Articles included in the analysis met the following criteria: (1) discussed the treatment of patients with substance abuse disorders, (2) focused on the treatment of opioid dependent patients, (3) discussed treatment with opioid agonist therapy, (4) discussed treatment by office-based physicians, (5) presented original research, and (6) provided data examining physician acceptance or satisfaction. RESULTS: Eight studies met the criteria. Their heterogeneity precluded aggregate analysis. Four of 8 studies revealed that providers had a positive perception concerning the efficacy of opioid agonist treatment, 4/8 indicated that providers believed that opioid dependent patients were more complex than others in their practices, and 3/8 studies indicated the need for additional support services. CONCLUSIONS: There are few studies of provider satisfaction with office-based treatment of opioid dependence. This literature reveals overall provider acceptance of this practice but highlights the need for support services. Further research, designed to identify the barriers to provider satisfaction with office-based opioid agonist therapy, is needed to ensure that these barriers do not limit expansion of this practice. 相似文献
59.
The impact of the Texas 1989 motorcycle helmet law on total and head-related fatalities, severe injuries, and overall injuries. 总被引:7,自引:0,他引:7
The State of Texas implemented a mandatory total motorcycle helmet law for all operators and passengers, effective September 1, 1989. In this study the impact of this intervention on frequency of both total and head-related fatalities, severe injuries, and overall injuries for operators during the subsequent year was quantified. This quantification is important because 26 states in the United States fail to have strict, mandatory helmet laws. The Box-Tiao time-series intervention methodology is used to estimate secular trends before and changes after the implementation of the law, analyzing Department of Public Safety monthly injury accident data for a period of 6 years collected from traffic accident reports filed for each motorcycle injury accident. Trends in fatalities and injuries (except for head-related deaths) estimated before implementation of the law approximated the 9.4% average annual decline in motorcycle registrations. Additional declines of 12.6% and 57.0%, respectively, were estimated for total and head-related fatalities during the year after the law was implemented. Declines of 13.1% and 54.6% were estimated for severe injuries for total and head-related accidents. Declines of 12.3% and 52.9% were found for total and head-related injuries overall. 相似文献
60.
Judith V. Becker PhD John A. Hunter PhD Dennis Goodwin BS Meg S. Kaplan PhD Douglas Martinez MA 《Sexual abuse : a journal of research and treatment》1992,5(1):45-51
Twenty adolescent male sexual offenders were evaluated by penile plethysmography on two separate occasions. Stimuli consisted of 19, two-minute audiotaped cues. Test-retest reliability was demonstrated for 15 of the 19 audiotaped vignettes. The highest correlations were found for those sexual behaviors in which the adolescents had engaged. 相似文献