全文获取类型
收费全文 | 24495篇 |
免费 | 8283篇 |
国内免费 | 163篇 |
专业分类
耳鼻咽喉 | 223篇 |
儿科学 | 547篇 |
妇产科学 | 469篇 |
基础医学 | 4926篇 |
口腔科学 | 955篇 |
临床医学 | 3764篇 |
内科学 | 6117篇 |
皮肤病学 | 532篇 |
神经病学 | 1911篇 |
特种医学 | 1715篇 |
外科学 | 5861篇 |
综合类 | 277篇 |
一般理论 | 11篇 |
预防医学 | 2831篇 |
眼科学 | 416篇 |
药学 | 1262篇 |
1篇 | |
中国医学 | 11篇 |
肿瘤学 | 1112篇 |
出版年
2021年 | 348篇 |
2020年 | 260篇 |
2018年 | 333篇 |
2017年 | 365篇 |
2016年 | 535篇 |
2015年 | 860篇 |
2014年 | 1461篇 |
2013年 | 2092篇 |
2012年 | 630篇 |
2011年 | 534篇 |
2010年 | 1151篇 |
2009年 | 1256篇 |
2008年 | 494篇 |
2007年 | 296篇 |
2006年 | 423篇 |
2005年 | 347篇 |
2004年 | 308篇 |
2002年 | 291篇 |
2001年 | 439篇 |
2000年 | 353篇 |
1999年 | 559篇 |
1998年 | 793篇 |
1997年 | 759篇 |
1996年 | 805篇 |
1995年 | 768篇 |
1994年 | 654篇 |
1993年 | 605篇 |
1992年 | 592篇 |
1991年 | 565篇 |
1990年 | 504篇 |
1989年 | 594篇 |
1988年 | 620篇 |
1987年 | 606篇 |
1986年 | 562篇 |
1985年 | 598篇 |
1984年 | 536篇 |
1983年 | 524篇 |
1982年 | 585篇 |
1981年 | 548篇 |
1980年 | 528篇 |
1979年 | 507篇 |
1978年 | 500篇 |
1977年 | 502篇 |
1976年 | 436篇 |
1975年 | 391篇 |
1974年 | 354篇 |
1973年 | 333篇 |
1972年 | 335篇 |
1971年 | 304篇 |
1970年 | 256篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
12.
The impact of AIDS on state and local health departments: issues and a few answers. 总被引:5,自引:5,他引:0 下载免费PDF全文
Owing to large differences in the incidence of AIDS (acquired immunodeficiency syndrome) and in public health resources and priorities, the impact of AIDS on state and local health departments has been variable. Nonetheless, health departments everywhere are being held responsible for surveillance and control of the HIV (human immunodeficiency virus) epidemic which we believe requires, at minimum, convenient, free HIV testing and counseling; expanded HIV services in sexually transmitted diseases clinics and substance treatment centers; locally oriented AIDS information/education; notification of persons unknowingly exposed to HIV; restrictive measures for HIV-infected persons who, after counseling, persist in exposing others; regulation or closure of public establishments in which HIV transmission is likely to result; and confidential reporting of all HIV test results to public health departments. In Colorado new legislation was passed to require reporting of HIV test results, to provide the reports with near absolute protections against unauthorized disclosure, and to modify quarantine statues to incorporate rights to due process, appeals, and confidentially. States in which there is a legal basis for discrimination against gay men will need to rectify this problem first. There is no evidence that reporting of HIV infections in Colorado has adversely affected the rate at which persons with HIV risk behaviors volunteer to be tested. For Denver and Colorado Departments of Health, more than 70 per cent of the estimated $2,796,000 expended in AIDS activities during 1987 was federal. 相似文献
13.
14.
Edwin B. Fisher Jr. 《Addictive behaviors》1997,22(6):680
The commodity model of social support and features of Nondirective Support may clarify varied results of support interventions for smoking cessation. A commodity model views social support as attractive in and of itself and as an alternative to high-risk choices such as smoking. If such support is easily accessible, a would-be quitter is less likely to choose to smoke. Consistent with the commodity model, social support interventions tend to be effective as long as support remains available, but they lose their effects when support is terminated. From a second approach, Nondirective Support entails accepting recipients' goals, cooperating without taking control, and validating recipients' feelings. In contrast, Directive Support entails taking control and telling recipients what to do and feel. Review of support interventions indicates the value of the continued availability of support suggested by the commodity model and of Nondirective Support's flexibility and responsiveness to the person. 相似文献
15.
Conditionally replicating luciferase reporter phages: improved sensitivity for rapid detection and assessment of drug susceptibility of Mycobacterium tuberculosis. 总被引:7,自引:1,他引:6 下载免费PDF全文
C Carrire P F Riska O Zimhony J Kriakov S Bardarov J Burns J Chan W R Jacobs Jr 《Journal of clinical microbiology》1997,35(12):3232-3239
TM4 is a lytic mycobacteriophage which infects mycobacteria of clinical importance. A luciferase reporter phage, phAE40, has been constructed from TM4 and was previously shown to be useful for the rapid detection and drug susceptibility testing of Mycobacterium tuberculosis. However, the lytic nature of the phage results in a loss of detectable light output and limits the sensitivity of detection. We describe several strategies aimed at improving the luciferase activity generated by TM4 luciferase phages, including (i) varying the position of the luciferase gene in the phage genome, (ii) isolating host-range mutants of the phage, and (iii) introducing temperature-sensitive mutations in the phage such that it will not replicate at the infecting temperature. Several new phages generated by these methods show increased intensity of luciferase production compared to the first-generation reporter phage phAE40, and one phage, phAE88, also demonstrates an enhanced duration of luciferase activity. This has allowed the detection of as few as 120 BCG cells and the determination of drug susceptibilities of M. tuberculosis in as little as 1 day. 相似文献
16.
An educational intervention was developed to improve family practice residents' ability to obtain useful information from pharmaceutical representatives. The curriculum is based on the traditional one-on-one drug detail. The objectives are to develop residents' skills in controlling the interview, promote skills for critically analyzing drug-promotional material, and discuss ethical issues. The contents include an assessment tool, suggested readings, and interview questions with rationale. After 5 years, residents' confidence in all areas of the curriculum improved significantly. 相似文献
17.
18.
Phase I study of high-dose cytosine arabinoside and etoposide in patients with advanced malignancies
Bayard L. Powell Hyman B. Muss Robert L. Capizzi Mary E. Caponera Douglas R. White Patricia J. Zekan James N. Atkins Don V. Jackson Jr. Frederick Richards II John B. Craig Julia M. Cruz Charles L. Spurr 《Cancer chemotherapy and pharmacology》1987,19(3):250-252
Summary Cytosine arabinsodie (ara-C) and etoposide (VP-16) display synergy in the laboratory. Twenty-six patients participated in a phase I study of high-dose ara-C in combination with VP-16. The dose of VP-16 was held constant at 50 mg/m2 as an intermittent infusion over 33 h; escalating doses of ara-C were given as infusions during hours 9–12 and 21–24. Myelosuppression was the dose-limiting toxicity and occurred with doses considerably less than those expected from studies of the two drugs as single agents. The suggested initial doses for phase II trials with this schedule are 750 mg/m2×2 doses of ara-C and 50 mg/m2 of VP-16. Nonhematologic toxicity was minimal; therefore, further dose escalation is feasible in patients in whom myelosuppression is acceptable.Supported in part by grants from the National Cancer Institute (CA-12197 and CA-09422) and the American Cancer Society CF-85-182 相似文献
19.
20.
Performance characteristics of pooled rabbit IgG polyclonal anti-C3d are compared with one mouse IgM and three mouse IgG monoclonal anti-C3d antibodies (MAs). IgG MA,s employed singly or in combination, failed to precipitate C3d; by contrast, IgM MA and polyclonal anti-C3d precipitated C3d. Measurements of polyclonal anti-C3d concentration by chemical means and by 125I-C3d radioimmunoassay (RIA) agreed closely. RIA values were 50% of chemical measurement values for three of the four MAs. Use of sucrose density gradient ultracentrifugation to assess MA C3d/anti-C3d molar combining ratios for soluble anti-C3d/C3d was not possible because fast-sedimenting multimeric C3d/anti-C3d complexes did not form. Dissociation and competitive binding studies indicate that (1) two MAs had substantially lower affinities than the other anti-C3d antibodies, and (2) polyclonal anti-C3d recognizes more C3d epitopes than are recognized by individual MAs. The results demonstrate antigenic complexity of C3d fragment and illustrate the difficulties of predicting individual MA performance based on prior experience with polyclonal antibodies. 相似文献