全文获取类型
收费全文 | 120611篇 |
免费 | 6172篇 |
国内免费 | 147篇 |
专业分类
耳鼻咽喉 | 1828篇 |
儿科学 | 5350篇 |
妇产科学 | 4072篇 |
基础医学 | 16785篇 |
口腔科学 | 2927篇 |
临床医学 | 8825篇 |
内科学 | 22979篇 |
皮肤病学 | 3429篇 |
神经病学 | 9314篇 |
特种医学 | 5192篇 |
外国民族医学 | 32篇 |
外科学 | 19737篇 |
综合类 | 1616篇 |
一般理论 | 30篇 |
预防医学 | 6072篇 |
眼科学 | 3446篇 |
药学 | 8331篇 |
中国医学 | 338篇 |
肿瘤学 | 6627篇 |
出版年
2018年 | 953篇 |
2017年 | 832篇 |
2016年 | 1166篇 |
2015年 | 1299篇 |
2014年 | 1726篇 |
2013年 | 2538篇 |
2012年 | 3339篇 |
2011年 | 3405篇 |
2010年 | 2109篇 |
2009年 | 2048篇 |
2008年 | 3448篇 |
2007年 | 3696篇 |
2006年 | 3837篇 |
2005年 | 3953篇 |
2004年 | 3855篇 |
2003年 | 3738篇 |
2002年 | 3689篇 |
2001年 | 7160篇 |
2000年 | 7074篇 |
1999年 | 5968篇 |
1998年 | 1691篇 |
1997年 | 1623篇 |
1996年 | 1392篇 |
1995年 | 1234篇 |
1994年 | 1137篇 |
1993年 | 1160篇 |
1992年 | 3832篇 |
1991年 | 3628篇 |
1990年 | 3619篇 |
1989年 | 3409篇 |
1988年 | 3041篇 |
1987年 | 2945篇 |
1986年 | 2854篇 |
1985年 | 2665篇 |
1984年 | 1975篇 |
1983年 | 1630篇 |
1982年 | 952篇 |
1981年 | 943篇 |
1980年 | 792篇 |
1979年 | 1870篇 |
1978年 | 1388篇 |
1977年 | 1145篇 |
1976年 | 965篇 |
1975年 | 1210篇 |
1974年 | 1246篇 |
1973年 | 1223篇 |
1972年 | 1079篇 |
1971年 | 1031篇 |
1970年 | 905篇 |
1969年 | 820篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Gender differences in facial reactions to facial expressions 总被引:3,自引:0,他引:3
This study explored whether males and females differ in facial muscle reactivity when exposed to facial expressions. The study also examined whether the sex of the stimulus faces differentially influences the response patterns to facial stimuli. Thus, the sex was manipulated in a 2 x 2 factorial design by exposing males and females to slides of angry and happy faces displayed by both sexes. Facial electromyographic (EMG) activity was measured from the corrugator and zygomatic muscle regions. The subjects were also required to rate the stimuli on different dimensions. The results showed that angry faces evoked increased corrugator activity whereas happy faces evoked increased zygomatic activity. As predicted, these effects were more pronounced for females, particularly for the response to happy faces. Interestingly, there were no facial EMG effects for gender of stimulus. It was further found that males and females perceived the stimuli similarly. The results are consistent with previous findings indicating that females are more facially reactive than are males. 相似文献
992.
Expression of tetanus toxin subfragments in vitro and characterization of epitopes. 总被引:1,自引:0,他引:1 下载免费PDF全文
B Andersen-Beckh T Binz H Kurazono T Mayer U Eisel H Niemann 《Infection and immunity》1989,57(11):3498-3505
993.
994.
Hendrik Schimmelpenning Elina T. Eriksson Bo Franzén Anders Zetterberg Gert U. Auer 《Virchows Archiv : an international journal of pathology》1993,423(4):273-279
The expression of theS-phase associated, nuclear protein proliferating cell nuclear antigen (PCNA) was investigated in routinely paraffin-embedded surgical specimens from 209 breast cancer patients. Cytometric DNA assessments were performed on fine-needle aspirates, upon which the primary diagnosis of breast cancer had been based. The mean clinical follow-up was 16 years (range 13–20 years). The percentage of PCNA immunoreactive tumour cells ranged between less than 5 to 60% (mean value 13.34%). There was a direct association between PCNA expression, high histological tumour grade (p<0.01), and DNA aneuploidy (p=0.009). In a subgroup of 22 patients with near-diploid DNA distribution patterns the PCNA expression yielded additional prognostic information. Patients with tumours of near-diploid DNA histograms and more than 20% of PCNA immunoreactive neoplastic cells had a significantly worse clinical course, than patients with neardiploid tumours containing less than 20% PCNA immunoreactive cells (p=0.0001). In contrast, the PCNA immunoreactivity did not yield additional prognostic information for patients with distinctly diploid or highly aneuploid tumour variants. In a multivariate analysis comprising all 209 patients, nodal status (p<0.01), tumour size (p<0.01), and DNA ploidy (p<0.01) were found to have significant prognostic effect. The findings indicate that carcinomas characterised by high proliferative activity and near-diploid DNA distribution patterns can show rapid tumour progression. The combined assessment of the PCNA immunoreactivity and of the nuclear DNA content in routinely processed surgical specimens of breast cancer patients appears to be of prognostic value. 相似文献
995.
M S Saag W G Powderly G A Cloud P Robinson M H Grieco P K Sharkey S E Thompson A M Sugar C U Tuazon J F Fisher 《The New England journal of medicine》1992,326(2):83-89
BACKGROUND. Intravenous amphotericin B, with or without flucytosine, is usually standard therapy for cryptococcal meningitis in patients with the acquired immunodeficiency syndrome (AIDS). Fluconazole, an oral triazole agent, represents a promising new approach to the treatment of cryptococcal disease. METHODS. In a randomized multicenter trial, we compared intravenous amphotericin B with oral fluconazole as primary therapy for AIDS-associated acute cryptococcal meningitis. Eligible patients, in all of whom the diagnosis had been confirmed by culture, were randomly assigned in a 2:1 ratio to receive either fluconazole (200 mg per day) or amphotericin B. Treatment was considered successful if the patient had had two consecutive negative cerebrospinal fluid cultures by the end of the 10-week treatment period. RESULTS. Of the 194 eligible patients, 131 received fluconazole and 63 received amphotericin B (mean daily dose, 0.4 mg per kilogram of body weight in patients with successful treatment and 0.5 mg per kilogram in patients with treatment failure; P = 0.34). Treatment was successful in 25 of the 63 amphotericin B recipients (40 percent; 95 percent confidence interval, 26 percent to 53 percent) and in 44 of the 131 fluconazole recipients (34 percent; 95 percent confidence interval, 25 percent to 42 percent) (P = 0.40). There was no significant difference between the groups in overall mortality due to cryptococcosis (amphotericin vs. fluconazole, 9 of 63 [14 percent] vs. 24 of 131 [18 percent]; P = 0.48); however, mortality during the first two weeks of therapy was higher in the fluconazole group (15 percent vs. 8 percent; P = 0.25). The median length of time to the first negative cerebrospinal fluid culture was 42 days (95 percent confidence interval, 28 to 71) in the amphotericin B group and 64 days (95 percent confidence interval, 53 to 67) in the fluconazole group (P = 0.25). Multivariate analyses identified abnormal mental status (lethargy, somnolence, or obtundation) as the most important predictive factor of a high risk of death during therapy (P less than 0.0001). CONCLUSIONS. Fluconazole is an effective alternative to amphotericin B as primary treatment of cryptococcal meningitis in patients with AIDS. Single-drug therapy with either drug is most effective in patients who are at low risk for treatment failure. The optimal therapy for patients at high risk remains to be determined. 相似文献
996.
B. Poch F. Gansauge S. Gansauge T. Anger U. Nilsson M. H. Schoenberg H. G. Beger 《Inflammation research》1996,45(8):428-433
Oxygen derived free radicals are involved in many pathological processes such as postischemic reperfusion injuries, hepatotoxicity of drugs and inflammatory processes. Thereby these oxygen radicals induce lipid peroxidation and perturbation of cellular membranes. The aim of our present study was to determine whether oxygen radicals generated by the xanthine oxidase/hypoxanthine system cause a release of histamine in human blood cell cultures. Stimulation of blood cell cultures with oxygen radicals induced a histamine liberation which was mainly due to calcium independent processes during the first 30 min, whereas then calcium requiring processes took part in the release of histamine. The regulation of the leukocyte selectin LECAM-1 was altered by oxygen radicals whereas histamine, which is known to modulate vascular selectin expression, did not affect the expression of LECAM-1. Our data indicate that oxygen radicals induce a direct calcium independent release of histamine which is due to membrane pertubating processes during the first phase but also induce a specific reaction leading to a further indirect histamine liberation which is probably mediated by PAF.accepted by W. LorenzThe first two authors contributed equally to this paper. 相似文献
997.
Genotoxicity testing of antiparasitic nitrofurans in the Drosophila wing somatic mutation and recombination test 总被引:2,自引:0,他引:2
Nifurtimox and eight structurally related 5-nitrofuran compounds active against Trypanosoma cruzi were tested for genotoxicity in the wing somatic mutation and recombination test in Drosophila melanogaster. Nifurtimox, compound ada and compound 1B were clearly mutagenic and recombinogenic whereas the remaining six compounds were negative. In contrast to the situation in bacterial mutagenicity tests, nitroreductase activity is probably not decisive for the genotoxicity of these compounds in Drosophila. The three non-genotoxic nitrofurans with high antiparasitic activity are promising candidates for the replacement of nifurtimox. However, these compounds require further genotoxicity testing in eukaryotic assay systems for a final evaluation. 相似文献
998.
Body awareness group therapy for patients with personality disorders. 2. Evaluation of the Body Awareness Rating Scale 总被引:1,自引:0,他引:1
The Body Awareness Rating Scale (BARS) was developed to evaluate the treatment process of the Body Awareness Group Therapy. The BARS subscales proved to have high interrater reliability. A factor analysis revealed two factors which seemed to measure one awareness and one movement dimension. The BARS was sensitive to change. As hypothesized, the BARS improvement enlarged with increasing duration of treatment. At discharge the good BARS outcome patients had improved significantly more than the poor BARS outcome ones, both concerning symptoms and global psychopathology. 相似文献
999.
Clostridium difficile toxins A and B inhibit human immune response in vitro. 总被引:1,自引:1,他引:1 下载免费PDF全文
Two Clostridium difficile toxins isolated from strain VPI 10463 were tested for their effect on different human T-cell proliferation systems. In mitogen- and antigen-driven T-cell proliferation systems, toxins inhibited the proliferative response in a dose-dependent fashion. In interleukin-2-driven culture systems, no effect of toxins could be found on preactivated T cells. We suspected that monocytes were the influenced cells, since in antigen- and mitogen-driven systems monocytes were necessary for the proliferative response, whereas the interleukin-2-driven system was independent of monocytes. To prove this concept, purified monocytes were treated with toxins. The treatment was found to markedly reduce the capacity of monocytes to stimulate T-cell proliferation. No inhibition of the proliferative response was measured when, instead of monocytes, resting or preactivated T cells were treated with toxins. These experiments clearly show that C. difficile toxins interact with monocytes and not with T cells. The effect of toxins on cells of the immune system might be one factor in the development of pseudomembranous colitis. 相似文献
1000.
H. Seibold U. Roth R. Lippert J. Kohler S. Wieshammer E. Henze M. Stauch 《Journal of molecular medicine (Berlin, Germany)》1986,64(9):433-441
Summary In patients with varying degrees of chronic obstructive pulmonary disease (COPD), simultaneous measurements of central hemodynamics and left ventricular radionuclide ventriculograms at rest and during exercise were made. In 21 of these patients, satisfactory echocardiograms could be performed. In seven of the patients, arterial blood pressure at rest was increased. Decreased compliance of the left ventricle was thought to be present in patients with COPD and additional arterial hypertension. The left ventricular ejection fraction (LVEF) at rest was in the high normal range in all patients. During exercise, no further increase was observed. This pattern of LVEF response seems to be typical in patients with COPD. Because the highest values were observed in the more severe COPD and right ventricular hypertrophy, it is unlikely that an impairment of left ventricular function is caused by COPD. In five of 27 patients, an abnormal decrease of LVEF and regional hypokinesis occurred during exercise, thus suggesting additional coronary heart disease. The fact that at least 30% of the patients with COPD suffered from arterial hypertension and 20% of the patients exhibited unexpected ischemia detected by regional hypokinesis in RNV during exercise, but not in the ECG, may be of practical relevance. Coronary angiography was not indicated because most of these patients were over 65 and the factor limiting the working capacity was ventilatory impairment and not angina pectoris, in all patients. For this reason, a diagnostic uncertainty remains with regard to additional coronary heart disease in the older patients with advanced chronic obstructive pulmonary disease.Lung Function Parameters VC (1)
inspiratory vital capacity
- FEV1 (1)
forced exspiratory volume in 1 sec
- Raw (cmH20/l/s)
airways resistance
- RV/TLC (%)
residual volume/total lung capacity
- paO2 (mm Hg)
O2 partial pressure
Hemodynamic Parameters CI (1/min/sqm)
cardiac index
- SVI (ml/sqm)
stroke volume index
- PAP (mm Hg)
pulmonary artery mean pressure
- PwP (mm Hg)
pulmonary capillary wedge pressure
- RRs (mm Hg)
systolic arterial pressure
- RRd (mm Hg)
diastolic arterial pressure (at the time of catheterization)
- RR(WHO) (mm Hg)
mean values measured at different days (at least 3 values).
Parameters Derived from Combined Radionuclide Ventriculography and Central Hemodynamics LVEF (%)
left ventricular ejection fraction
- LVESVI (ml/sqm)
left ventricular endsystolic volume index
- P/V (mm Hg/ml/sqm)
peak systolic pressure/endsystolic volume index
- PFR (1/sec)
peak filling rate: endsystolic volume/sec
Echocardiographic Parameters RV d wth (mm)
right ventricular enddiastolic wall thickness
- LV d wth (mm)
left ventricular enddiastolic wall thickness
In honor to Prof. W.E. Adam's 60th birthday 相似文献