全文获取类型
收费全文 | 1764篇 |
免费 | 142篇 |
国内免费 | 46篇 |
专业分类
耳鼻咽喉 | 7篇 |
儿科学 | 83篇 |
妇产科学 | 37篇 |
基础医学 | 173篇 |
口腔科学 | 39篇 |
临床医学 | 230篇 |
内科学 | 571篇 |
皮肤病学 | 28篇 |
神经病学 | 125篇 |
特种医学 | 186篇 |
外科学 | 154篇 |
综合类 | 39篇 |
预防医学 | 93篇 |
眼科学 | 37篇 |
药学 | 70篇 |
1篇 | |
中国医学 | 9篇 |
肿瘤学 | 70篇 |
出版年
2023年 | 9篇 |
2022年 | 8篇 |
2021年 | 25篇 |
2020年 | 18篇 |
2019年 | 31篇 |
2018年 | 46篇 |
2017年 | 33篇 |
2016年 | 34篇 |
2015年 | 35篇 |
2014年 | 57篇 |
2013年 | 70篇 |
2012年 | 57篇 |
2011年 | 71篇 |
2010年 | 58篇 |
2009年 | 84篇 |
2008年 | 63篇 |
2007年 | 89篇 |
2006年 | 69篇 |
2005年 | 65篇 |
2004年 | 44篇 |
2003年 | 43篇 |
2002年 | 38篇 |
2001年 | 46篇 |
2000年 | 33篇 |
1999年 | 35篇 |
1998年 | 75篇 |
1997年 | 85篇 |
1996年 | 59篇 |
1995年 | 55篇 |
1994年 | 41篇 |
1993年 | 48篇 |
1992年 | 35篇 |
1991年 | 40篇 |
1990年 | 29篇 |
1989年 | 37篇 |
1988年 | 33篇 |
1987年 | 39篇 |
1986年 | 30篇 |
1985年 | 27篇 |
1984年 | 16篇 |
1983年 | 22篇 |
1982年 | 17篇 |
1981年 | 12篇 |
1980年 | 15篇 |
1979年 | 5篇 |
1978年 | 8篇 |
1977年 | 11篇 |
1976年 | 8篇 |
1968年 | 4篇 |
1967年 | 4篇 |
排序方式: 共有1952条查询结果,搜索用时 31 毫秒
11.
To find out the efficacy of sucralfate in preventing gastrointestinal side effects of non-steroidal anti-inflammatory drugs (NSAIDs) a prospective, randomised single blind study was conducted from 1989 to 1992. Patients with osteoarthritis, rheumatoid arthritis and other long standing painful conditions, who were expected to receive NSAIDs for over three months, were recruited into the study. All medicines were discontinued for a period of 10–15 days prior to initial endoscopic assessment. NSAID therapy was started and the patients were randomised to receive either placebo (group A) or sucralfate (group B) in addition. Patient were reassessed clinically every week and an endoscopic examination was repeated after 6–8 weeks of follow-up. A total of 176 patients were studied in group A (n=91) and group B (n=85). At the end of 8 weeks gastrointestinal symptoms were present in 30.6% and 26.4% patients of group A and B respectively. Endoscopic assessment showed superficial lesions in 36.5% and 18.7% while endoscopic ulcer in 2.4% and 1.1% patients of groups A and B respectively. Thus in patients receiving chronic NSAID therapy, simultaneous administration of sucralfate reduces the incidence of superficial gastric lesions but has no significant effect on symptoms or ulcer formation.KEY WORDS: Gastropathy, Sucralfate, Nonsteroidal anti-inflammatory drugs 相似文献
12.
The foveal increment threshold spectral sensitivity function for a 500 msec raised cosine stimulus without spatial edges exhibits a sharp drop or "notch" in sensitivity that coincides with the wavelength of a long-wavelength adapting field. An appropriate name for this phenomenon is the "Sloan notch", after Louise Sloan, who first observed a notch in a foveal threshold spectrum. We have examined suprathreshold discriminability on both sides of the Sloan notch produced by a 6700 td, 578 nm adapting field. In a temporal two-alternative forced-choice paradigm, a suprathreshold 650 nm low-frequency "standard" stimulus was paired with low-frequency "test" stimuli, of wavelength between 600 and 670 nm and varied intensity; the observer's task was to identify the interval containing the standard. Discriminability of the test and standard typically dropped to chance for some particular test intensity, producing "indiscriminability action spectra", up to 0.7 log units above threshold. Truncated spectra (between about 530 and 560 nm) were also obtained from observers on the middle wavelength side of the Sloan notch, for a 550 nm standard. The indiscriminability action spectra of each observer were identical, up to scaling, with the observer's threshold action spectrum. Analysis of the action spectra shows that the indiscriminable stimuli are rendered equivalent at the input to a neural pathway where L- and M-cone signals converge with opposite sign. We also investigated discriminability in the spectral region containing and immediately surrounding the Sloan notch. Suprathreshold stimuli in the spectral region near the notch produce percepts that are always discriminable from 650 and 550 nm standards (and from one another), and thus we conclude that in this spectral region, perception is mediated in part by a pathway distinct from that which signals the standards. The action spectrum of this latter pathway was estimated with a variant of the discrimination procedure, and found similar to V lambda over the spectral region 575-610 nm. 相似文献
13.
A significant number of casualties in previous conflicts died from peripheral vascular wounds. A well-designed tourniquet could possibly have prevented these deaths. The objective of this study was the identification of such a tourniquet. A survey of Special Operations corpsmen established important characteristics necessary in an ideal tourniquet. Because most available devices do not and patented ideas could not meet these criteria, a number of prototypes were developed. Seven potentially satisfactory tourniquets were evaluated by 15 Navy SEAL corpsmen. The success and timing of placement were recorded, and a follow-up questionnaire was completed. Of the several successful tourniquets, two were preferred. Tourniquets incorporating a windlass technique take longer to place and often fail when placed with only one hand. New, relatively simple tourniquet devices incorporating bladder and ratchet mechanisms can significantly improve tourniquet performance. 相似文献
14.
Linear lesions in myocardium created by Nd:YAG laser using diffusing optical fibers: in vitro and in vivo results 总被引:3,自引:0,他引:3
Fried NM Lardo AC Berger RD Calkins H Halperin HR 《Lasers in surgery and medicine》2000,27(4):295-304
BACKGROUND AND OBJECTIVE: Linear lesions may be necessary for successful catheter ablation of cardiac arrhythmias such as atrial fibrillation. This study uses laser energy delivered through diffusing optical fibers as an alternative to radiofrequency energy for the creation of linear lesions in cardiac tissue in a single application. STUDY DESIGN/MATERIALS AND METHODS: Samples of canine myocardium were placed in a heated, circulating saline bath and irradiated with a 1.06-microm, continuous-wave Nd:YAG laser during in vitro studies. Laser ablation was then performed in vivo on the epicardial surface of the right ventricle during an open-chest procedure by using similar ablation parameters. Laser energy was delivered to the tissue by being diffused radially through flexible optical fiber tips oriented parallel to the tissue surface. Histology and temperature measurements verified transmurality, continuity, and linearity of the lesions. RESULTS: Peak tissue temperatures measured in vitro remained low (51 +/- 1 degrees C at the endocardial surface, 61 +/- 6 degrees C in the mid-myocardium, and 55 +/- 6 degrees C at the epicardial surface) with no evidence of tissue charring or vaporization. Lesion dimensions produced in vitro and in vivo were similar (depth, 6 mm; width, 8-10 mm; length, 16-22 mm), demonstrating that tissue perfusion in vivo did not significantly alter the heating. CONCLUSION: Long linear lesions, necessary for duplication of the surgical maze procedure during catheter ablation of atrial fibrillation, may be created by using laser radiation delivered through flexible diffusing optical fiber tips. Further development of steerable catheters for endocardial atrial ablation and studies correlating thermal damage zones with electrophysiologic indicators of irreversible conduction block are warranted. 相似文献
15.
BACKGROUND: Despite an increased awareness among clinicians regarding pain and pain management for infants undergoing surgery, pain associated with procedures performed outside the operating room may not be adequately managed. PURPOSE: To examine the beliefs and self-described behavior of physicians and nurses regarding the management of procedural pain in newborn infants. METHODS: A survey was distributed to 467 clinicians (nurses and physicians) working in 11 level II and 4 level III nurseries in a large metropolitan area. Respondents were asked to rate the painfulness of 12 common bedside nursery procedures and how often pharmacologic and nonpharmacologic (comfort) measures are currently used and should be used for those procedures. Demographic data were also collected. RESULTS: Surveys were completed by 374 clinicians (80% response rate). Physicians and nurses believe infants feel as much pain as adults and that 9 of the 12 listed procedures are moderately to very painful. Neither pharmacologic nor comfort measures are believed to be used frequently, even for the most painful procedures. Physicians and nurses believe both pharmacologic and comfort measures should be used more frequently, but nurses believe comfort measures should be used more frequently than do physicians. Beliefs about infant pain and procedural pain were related to pain management preferences. Physicians' but not nurses' ratings were associated with significant personal pain. CONCLUSIONS: Despite their beliefs that infants experience significant procedure-related pain, clinicians believe pain management for infants remains below optimal levels. Barriers to more consistent and effective pain management need to be identified and surmounted. 相似文献
16.
17.
An Australian study of functional status after childbirth 总被引:1,自引:0,他引:1
18.
19.
Non-invasive detection of fecal protein kinase C betaII and zeta messenger RNA: putative biomarkers for colon cancer 总被引:2,自引:0,他引:2
Davidson LA; Aymond CM; Jiang YH; Turner ND; Lupton JR; Chapkin RS 《Carcinogenesis》1998,19(2):253-257
We have developed a non-invasive method utilizing feces, containing
sloughed colonocytes, as a sensitive technique for detecting diagnostic
colonic biomarkers. In this study, we used the rat colon carcinogenesis
model to determine if changes in fecal protein kinase C (PKC) expression
have predictive value in monitoring the neoplastic process. Weanling rats
were injected with saline or azoxymethane (AOM) and 36 weeks later fecal
samples and mucosa were collected, poly A+ RNA isolated, and quantitative
RT-PCR performed using primers to PKC betaII and zeta. Fecal PKC betaII and
zeta mRNA levels were altered by the presence of a tumor, with
tumor-bearing animals having a 3-fold higher (P < 0.05) PKC betaII
expression as compared with animals without tumors. In addition,
AOM-injection increased mucosal PKC betaII mRNA expression compared with
saline controls. No effect of tumor incidence on mucosal PKC betaII
expression was observed. In contrast, fecal PKC zeta expression was
2.5-fold lower (P < 0.05) in animals injected with azoxymethane versus
saline. Since tumor incidence exerts a reciprocal effect on fecal PKC
betaII and zeta mRNA expression, data were also expressed as the ratio
between PKC betaII and zeta. The isozyme ratio was strongly related to
tumor incidence, i.e. ratio for animals with tumors was 2.18 +/- 1.25,
animals without tumors was 0.50 +/- 0.16, P = 0.025. We demonstrate that
the expression of fecal PKC betaII and zeta may serve as a noninvasive
marker for development of colon tumors. A sensitive technique for the
detection of colon cancer is of importance since early diagnosis can
substantially reduce mortality.
相似文献
20.