全文获取类型
收费全文 | 13928篇 |
免费 | 1564篇 |
国内免费 | 40篇 |
专业分类
耳鼻咽喉 | 244篇 |
儿科学 | 464篇 |
妇产科学 | 307篇 |
基础医学 | 2153篇 |
口腔科学 | 230篇 |
临床医学 | 1818篇 |
内科学 | 2901篇 |
皮肤病学 | 175篇 |
神经病学 | 892篇 |
特种医学 | 470篇 |
外科学 | 1767篇 |
综合类 | 378篇 |
一般理论 | 12篇 |
预防医学 | 1543篇 |
眼科学 | 163篇 |
药学 | 1102篇 |
中国医学 | 5篇 |
肿瘤学 | 908篇 |
出版年
2022年 | 101篇 |
2021年 | 195篇 |
2020年 | 126篇 |
2019年 | 202篇 |
2018年 | 230篇 |
2017年 | 196篇 |
2016年 | 189篇 |
2015年 | 222篇 |
2014年 | 298篇 |
2013年 | 448篇 |
2012年 | 635篇 |
2011年 | 661篇 |
2010年 | 340篇 |
2009年 | 327篇 |
2008年 | 548篇 |
2007年 | 654篇 |
2006年 | 589篇 |
2005年 | 598篇 |
2004年 | 580篇 |
2003年 | 598篇 |
2002年 | 523篇 |
2001年 | 476篇 |
2000年 | 528篇 |
1999年 | 468篇 |
1998年 | 210篇 |
1997年 | 191篇 |
1996年 | 166篇 |
1995年 | 163篇 |
1994年 | 156篇 |
1993年 | 133篇 |
1992年 | 357篇 |
1991年 | 342篇 |
1990年 | 332篇 |
1989年 | 333篇 |
1988年 | 282篇 |
1987年 | 277篇 |
1986年 | 255篇 |
1985年 | 267篇 |
1984年 | 181篇 |
1983年 | 152篇 |
1982年 | 125篇 |
1981年 | 99篇 |
1980年 | 104篇 |
1979年 | 205篇 |
1978年 | 140篇 |
1977年 | 109篇 |
1976年 | 106篇 |
1974年 | 111篇 |
1973年 | 100篇 |
1972年 | 101篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Twenty-five persons with diabetes (aged 55–83 years) who were living independently in the community, and 40 age- and sex-matched non-diabetic controls were assessed for tactile sensitivity, vibration sense, proprioception, quadriceps strength and body sway. In both men and women, those with diabetes performed significantly worse in tests of body sway on firm and compliant surfaces compared with the control subjects after controlling for weight and body mass index. The female diabetic subjects also performed significantly worse in tests of peripheral sensation and strength compared with controls. Age-related declines in sensori-motor function were greater in the diabetic group (r = 0.55–0.75) than in the controls (r < 0.44), while within the diabetic group, duration of diabetes and vibration sense were significantly correlated with sway on a compliant (foam rubber) surface with the eyes open (partial r = 0.52, p < 0.01 and r = 0.55, p < 0.01, respectively). The study findings provide evidence that older people with diabetes have problems with stability and related sensori-motor factors which may place them at increased risk of falls. 相似文献
82.
Amy Y. Chen MD MPH Nicole Schrag MSPH Yongping Hao PhD W. Dana Flanders MD DSc James Kepner PhD Andrew Stewart MS Elizabeth Ward PhD 《Otolaryngology--head and neck surgery》2006,135(6):831-837
OBJECTIVE: In 1991, a randomized study was published and demonstrated that use of nonsurgical therapy (chemoradiation) provided similar survival to total laryngectomy (the gold standard) for patients with advanced-stage laryngeal cancer. The purpose of this study was to assess how treatment of advanced laryngeal cancer was influenced by such developments in non-surgical therapy. STUDY DESIGN: Patterns of care study using National Cancer Database (1985-2001). RESULTS: The percentage of advanced-stage patients treated with chemoradiation increased from 8.3% to 20.8% while the proportion treated with radiation alone decreased from 38.9% to 23.0%. Use of chemoradiation increased at a significantly faster rate after the 1991 publication at both community cancer centers and teaching research facilities. The use of total laryngectomy decreased slightly during this period. CONCLUSIONS: The use of chemoradiation increased after the 1991 publication. It was impossible to determine from the NCDB whether additional patients who could benefit from chemo-RT were not offered or did not complete this treatment option. We recommend that treatment recommendations discussed at tumor boards be recorded in cancer registries. 相似文献
83.
Pulmonary disease during the treatment of rheumatoid arthritis with low dose pulse methotrexate 总被引:11,自引:0,他引:11
C W Carson G W Cannon M J Egger J R Ward D O Clegg 《Seminars in arthritis and rheumatism》1987,16(3):186-195
Methotrexate therapy has been effective in the treatment of RA with short term experience suggesting little serious adverse reactions. Our review of 168 patients receiving methotrexate has identified nine patients with probable or possible methotrexate-induced pulmonary toxicity, giving a prevalence of 5% and an incidence of 3.9 per 100 patients per year. No clinical or laboratory features showed an association that could potentially predict the development of pulmonary disease. All patients experienced complete recovery with supportive care and/or corticosteroid therapy. Clinical monitoring for this complication is warranted in all patients receiving long term methotrexate therapy for RA. 相似文献
84.
Safety, tolerance, and pharmacokinetics of atevirdine mesylate (U-87201E) in asymptomatic human immunodeficiency virus-infected patients.
下载免费PDF全文
![点击此处可从《Antimicrobial agents and chemotherapy》网站下载免费的PDF全文](/ch/ext_images/free.gif)
85.
The mode of action and the structure of a herbicide in complex with its target: binding of activated hydantocidin to the feedback regulation site of adenylosuccinate synthetase. 总被引:4,自引:0,他引:4
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
R Fonné-Pfister P Chemla E Ward M Girardet K E Kreuz R B Honzatko H J Fromm H P Sch?r M G Grütter S W Cowan-Jacob 《Proceedings of the National Academy of Sciences of the United States of America》1996,93(18):9431-9436
(+)-Hydantocidin, a recently discovered natural spironucleoside with potent herbicidal activity, is shown to be a proherbicide that, after phosphorylation at the 5' position, inhibits adenylosuccinate synthetase, an enzyme involved in de novo purine synthesis. The mode of binding of hydantocidin 5'-monophosphate to the target enzyme was analyzed by determining the crystal structure of the enzyme-inhibitor complex at 2.6-A resolution. It was found that adenylosuccinate synthetase binds the phosphorylated compound in the same fashion as it does adenosine 5'-monophosphate, the natural feedback regulator of this enzyme. This work provides the first crystal structure of a herbicide-target complex reported to date. 相似文献
86.
The respiratory-dependent pacemaker (RDP3 or MB-1, Biorate, Biotec International, S.p.A., Bologna, Italy) detects the respiratory rate by measuring thoracic impedance using a subcutaneous auxiliary lead. The sensed respiratory rate is used to determine the pacing rate response. This pacemaker had been implanted in 9 patients with a mean age of 58 (range 42-69) years. During symptom-limited treadmill exercise, rate-modulated pacing resulted in a significant increase in pacing rate (mean +/- SD, 124 +/- 10 vs. 71 +/- 3 beats/min p less than 0.001) and exercise capacity (343 +/- 147 vs. 463 +/- 120 s, p less than 0.05) compared to those achieved with constant rate ventricular pacing. Brief treadmill exercise tests showed appropriate rate response to increased walking speed and gradient. However, rate response was modified by arm swinging-induced motion artefact which affected the measured "impedance." Complications observed on follow-up included perforation of the auxiliary lead in 2 patients and symptomatic myopotential interference in 3 patients with the RDP3 pacemaker, all of whom required unit replacement. It is concluded that although the respiratory-dependent pacemaker can confer physiological benefit in patients with bradycardia, myopotential interference (largely overcome by the new version MB-1 with programmable sensitivity) and the auxiliary lead can be problematic in some patients. 相似文献
87.
Activation of complement by hydroxyl radical in thermal injury 总被引:6,自引:0,他引:6
Complement activation resulting from local burn injury of skin and other soft tissues can be linked to systemic complications, such as intravascular hemolysis, neutrophil activation, and acute lung injury. This study was designed to clarify the relationship between cutaneous thermal injury, oxygen radical formation, and complement activation in vivo. A model for "selective" venous sampling from the area of a partial-thickness cutaneous burn over 25% to 30% of the total body surface in the rat was developed. Interventions involving oxygen radical scavengers, antioxidant enzymes, xanthine oxidase inhibitors, an iron chelator, complement depletion, and neutrophil depletion were used to probe the nature of the oxygen products involved in complement activation. Plasma from the area of burn was examined for total hemolytic complement activity, content of C5a-related chemotactic peptide, and relationship of oxygen products to appearance of this peptide. Xanthine oxidase inhibitors, hydroxyl radical scavengers, and complement depletion diminished the generation of C5a activity at the burn site, whereas neutrophil depletion was without effect. These data suggest that C5a activity may be related to oxygen products from xanthine oxidase. The catalase sensitivity and iron dependency of C5a generation suggest that hydroxyl radical may be related to complement activation and C5a appearance. This is the first report to directly link oxygen radical generation and complement activation in vivo. 相似文献
88.
Hypoxemia is a nearly constant accompaniment of head injury. Diverse theories have been proposed to explain this relationship. The authors report the case of a patient who suffered an episode of severe, transient, arterial oxygen desaturation during "controlled" brain trauma: an otherwise uneventful stereotaxic biopsy of a small germinoma of the hypothalamus. Evidence is provided that pure ventilation-perfusion mismatching, without pulmonary edema, underlay the hypoxemia. The hypothalamus is intimately involved in matching pulmonary ventilation to perfusion; the hypoxemia of various brain injuries may be mediated by perturbation of this structure. 相似文献
89.
L Weiss P M Ward 《International journal of cancer. Journal international du cancer》1988,41(3):450-455
The present studies are based on autopsy data showing that in upper esophageal and lower rectal carcinomas, hematogenous metastasis occurs mainly first to the lungs, and cancer cells from pulmonary metastases generate arterial metastases. In lower esophageal and upper rectal carcinomas, hematogenous metastases occur first in the liver, then in the lungs, and are further disseminated by the arterial route. The arterial metastatic patterns are different in the 2 groups. One possible explanation for these differences in pattern is that liver "residence" is associated with different metastatic behavior; this has been tested in a model system. Experiments with the transplantable colon-26 carcinoma in mice reveal that, when cancer cells from common s.c. transplant sites are grown in the liver, lungs or liver-and-lungs, and then injected into the bloodstream of fresh recipients via the left ventricle, the portal vein or the tail vein, different patterns and degrees of colonization of 11 different target sites are observed. These results are consistent with the hypothesis that growth of cancers in different anatomic sites may modify the subsequent arterial metastatic patterns, due to site-induced changes occurring in cancer cell populations, which influence metastasis from metastases or so-called "cascade" processes. 相似文献
90.
Simultaneous visualization of seven different DNA probes by in situ hybridization using combinatorial fluorescence and digital imaging microscopy. 总被引:14,自引:5,他引:9
下载免费PDF全文
![点击此处可从《Proceedings of the National Academy of Sciences of the United States of America》网站下载免费的PDF全文](/ch/ext_images/free.gif)
T Ried A Baldini T C Rand D C Ward 《Proceedings of the National Academy of Sciences of the United States of America》1992,89(4):1388-1392
Combinatorial labeling of probes (i.e., with two or more different reporters) increases the number of target sequences that can be detected simultaneously by fluorescence in situ hybridization. We have used an epifluorescence microscope equipped with a digital imaging camera and computer software for pseudocoloring and merging images to distinguish up to seven different probes using only three fluorochromes. Chromosome-specific centromere repeat clones and chromosome-specific "composite" probe sets were generated by PCR in which different mixtures of modified nucleotides, including fluorescein-conjugated dUTP, were incorporated. Cosmid clones were labeled similarly by nick-translation. The technique has been used to delineate the centromeres of seven different human chromosomes, on both 4',6-diamidino-2-phenylindole-stained metaphase spreads and interphase nuclei, to map six cosmid clones in a single hybridization experiment and to detect chromosome translocations by chromosome painting. Multiparameter hybridization analysis should facilitate molecular cytogenetics, probe-based pathogen diagnosis, and gene mapping studies. 相似文献