全文获取类型
收费全文 | 767篇 |
免费 | 35篇 |
国内免费 | 1篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 14篇 |
妇产科学 | 13篇 |
基础医学 | 74篇 |
口腔科学 | 4篇 |
临床医学 | 169篇 |
内科学 | 144篇 |
皮肤病学 | 4篇 |
神经病学 | 75篇 |
特种医学 | 92篇 |
外科学 | 92篇 |
综合类 | 4篇 |
一般理论 | 2篇 |
预防医学 | 42篇 |
眼科学 | 8篇 |
药学 | 33篇 |
中国医学 | 2篇 |
肿瘤学 | 21篇 |
出版年
2022年 | 2篇 |
2021年 | 10篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 7篇 |
2017年 | 10篇 |
2016年 | 6篇 |
2015年 | 12篇 |
2014年 | 12篇 |
2013年 | 31篇 |
2012年 | 33篇 |
2011年 | 29篇 |
2010年 | 36篇 |
2009年 | 22篇 |
2008年 | 63篇 |
2007年 | 51篇 |
2006年 | 44篇 |
2005年 | 42篇 |
2004年 | 37篇 |
2003年 | 51篇 |
2002年 | 52篇 |
2001年 | 16篇 |
2000年 | 28篇 |
1999年 | 22篇 |
1998年 | 16篇 |
1997年 | 14篇 |
1996年 | 7篇 |
1995年 | 12篇 |
1994年 | 11篇 |
1993年 | 8篇 |
1992年 | 18篇 |
1991年 | 7篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1985年 | 11篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1977年 | 2篇 |
1976年 | 4篇 |
1975年 | 3篇 |
1973年 | 3篇 |
1972年 | 3篇 |
1967年 | 2篇 |
1956年 | 2篇 |
1942年 | 4篇 |
排序方式: 共有803条查询结果,搜索用时 31 毫秒
51.
Effects of temperature on chemical toxicity to a collembolan,Folsomia candida, in relation to time were studied in this experiment. Field soil was used as a test substrate. Collembolans were incubated at three different temperatures (+13, +16, and +19°C) and in two different dimethoate concentrations (1 and 3 mg/kg), clean soil serving as the control. Four destructive samplings were done at 2-week intervals. Dimethoate degradation was also analyzed. Dimethoate 1 mg/kg had a slight effect on both adult growth and reproduction, whereas 3 mg/kg was fatal toF. candidain the soil used. Toxic effects tended to last longer at low temperature than at high temperature, but the differences were not extensive. Temperature was negatively correlated with adult growth but positively correlated with reproduction. The dimethoate degradation rate was similar at all temperatures but differed with the concentration. 相似文献
52.
Laitinen HM Toppila EM Olkinuora PS Kuisma K 《Applied occupational and environmental hygiene》2003,18(3):177-182
The purpose of the study was to determine how and when the personnel of the Finnish National Opera are exposed to noise and whether exposure depends on musical selection of repertoire. Additionally, an evaluation of sound exposure level due to individual rehearsals was included. The measurements were done using individual noise dosimeters and fixed-point measurements. From the measurements, annual noise exposure in the Opera was evaluated. The conductors, dancers, and double bass players were exposed to levels below 85 decibels, A-weighted, dB(A), which is the national action level. The choir members were exposed to sound levels of 92 and 94 dB(A). Within the orchestra, the highest sound exposure levels were found among percussionists, 95 dB(A); flute/piccolo players, 95 dB(A); and brass players, 92-94 dB(A). Other sound exposure levels among orchestra members varied from 83 to 89 dB(A). Soloists and rehearsal pianists are likely to be exposed to sound levels exceeding the national action level. From an exposure perspective, the individual rehearsals, 79-100 dB(A), proved to be as important as performances and group rehearsals, 82-99 dB(A), among orchestra musicians and choir singers. The ambient sound level for the lighting crew was 76 +/- 4 dB(A). However, the measured sound levels at the ear varied from 77 to 92 dB(A) due to the communication via headphones that had individual volume control. For the majority of personnel of the Finnish National Opera, sound exposure level exceeded the national action level value of 85 dB(A). Artists exceeded the action level during both individual and group rehearsals, as well as during performances. Hearing protection has been designed for musicians. Education/reinforcement is required to ensure it is worn. 相似文献
53.
Saku Väätäinen Henri Tuomilehto Jouko Saramies Jaakko Tuomilehto Hannu Uusitalo Esko Hussi Sirkka Keinänen-Kiukaanniemi Janne Martikainen 《Quality of life research》2013,22(10):2737-2748
Purpose
The aim of the study is to examine the health-related quality-of-life (HRQOL) impact of the nocturnal awakenings and the duration of the sleep in the Finnish middle-aged and older population.Methods
Cross-sectional sample consisted of 823 community-dwelling persons aged 55–75 living in a single municipality in a rural area of Eastern Finland. Frequency of the nocturnal awakenings was dichotomized as reporting “frequent,” if the participant reported subjectively awakening “often” or “very often,” and “infrequent” if the participant reported awakening “sometimes” or less frequently. HRQOL was measured with a preference-based HRQOL-index instrument, 15D. Analyses were adjusted for gender, BMI, morbidities, depression, employment and marital status, current smoking and drinking, exercise, recommendation to exercise from a health care professional, and subjective opinion about own exercise habits.Results
Frequent nocturnal awakenings had statistically and clinically significant negative impact on HRQOL, the mean (SE) adjusted marginal HRQOL impact being ?0.0416 (0.006). More than 10 and less than 6.5 h of daily sleep were associated with higher probability of having low HRQOL, adjusted odd ratios (95 % CI) being 2.65 (1.11–6.33) and 2.65 (1.55–4.52), respectively. However, the changes in daily sleep duration did not have noticeable influence on the significance or magnitude of the negative HRQOL impact of the frequent nocturnal awakenings.Conclusions
Nocturnal awakenings displayed a strong independent association with decreased HRQOL. The findings suggest that both clinicians and researchers should pay closer attention to nocturnal awakenings and other sleep problems in order to find ways to improve the quality of life in individuals with such conditions. 相似文献54.
Chinese hamster ovary cell adhesion to human platelet thrombospondin is dependent on cell surface heparan sulfate proteoglycan. 总被引:9,自引:0,他引:9 下载免费PDF全文
P R Kaesberg W B Ershler J D Esko D F Mosher 《The Journal of clinical investigation》1989,83(3):994-1001
Thrombospondin is a 420-kD platelet alpha-granule glycoprotein that binds specifically to heparin. We examined adhesion to thrombospondin of CHO K1 cells and three mutant CHO lines with varying deficiencies in glycosaminoglycan (GAG) synthesis. In an experiment in which the parent line (K1) had 78% adherence to thrombospondin adsorbed to tissue culture plastic, CHO S745 cells, with less than 6% normal GAG synthesis had 11% adherence. CHO S677 cells, with decreased heparan sulfate proteoglycan but increased chondroitin sulfate proteoglycan, had 42% adherence. CHO S803 cells, with decreased heparan sulfate proteoglycan and normal chondroitin sulfate proteoglycan, had 31% adherence. Heparin inhibited K1 cell adhesion to thrombospondin, but not fibronectin, in a concentration-dependent manner. Dermatan sulfate but not chondroitin sulfate was also inhibitory. There was markedly decreased K1 cell adhesion to a thrombospondin core fragment that lacked the heparin binding NH2-terminal domain. Purified heparin binding domain, although poorly adhesive when adsorbed to substratum, inhibited cell adhesion to intact thrombospondin. Adhesion was better for all cell lines tested, including three human tumor cell lines, when thrombospondin was adsorbed at pH 4.0 compared with pH 7.4. When adsorption of thrombospondin was done at pH 7.4, cell adhesion was better when thrombospondin was adsorbed in the presence of greater than or equal to 0.6 mM calcium, compared to 0.1 mM calcium or EDTA. These findings suggest that thrombospondin can adsorb to plastic with varying degrees of exposure of a cell adhesion domain. We conclude that the thrombospondin cell adhesion receptor on CHO cells is a heparan sulfate proteoglycan, and that cell adhesion to thrombospondin depends on conformation of adsorbed thrombospondin. 相似文献
55.
S Antila H Huuskonen T Nevalainen H Kanerva P Vanninen L Lehtonen 《European journal of pharmaceutical sciences》1999,9(1):85-91
Site specific bioavailability and metabolism of levosimendan was studied in ten dogs by placing intestinal access port catheters in different parts of the gastrointestinal tract. 14C-labelled levosimendan (0.1 mg/kg) was administered intravenously, by gastric tube and directly through catheters that were placed in the duodenum, jejunum and ileum. Plasma samples were collected and radioactivity in the different organs and tissues was measured. The results of the present study showed that bioavailability of levosimendan was high varying from 71 to 86% after extravascular administration. Metabolite OR-1855 concentrations in the plasma were about 3-4 times higher after administration to the ileum compared to the other administration routes. It can be concluded that the bioavailability of levosimendan is not affected by site specific administration. The bacteria or enzymes responsible for the metabolism of levosimendan are located in the lower parts of the gastrointestinal tract. 相似文献
56.
Early sequential changes in serum markers of acute pancreatitis induced by endoscopic retrograde cholangiopancreatography. 总被引:3,自引:0,他引:3
Marko Lempinen Ulf-H?kan Stenman Jorma Halttunen Pauli Puolakkainen Reijo Haapiainen Esko Kemppainen 《Pancreatology》2005,5(2-3):157-164
BACKGROUND/AIMS: Trypsinogen activation is thought to play a crucial role in the pathogenesis of acute pancreatitis (AP). Our aim was to characterize the very early sequential changes of trypsinogen-1, trypsinogen-2, the trypsin-2-alpha1-antitrypsin complex (T2-AAT), and pancreatic secretory trypsin inhibitor (PSTI) in serum from patients with pancreatitis induced by endoscopic retrograde cholangiopancreatography (ERCP), a model for studying the early phase of the disease in humans. PATIENTS AND METHODS: The study population consisted of 659 consecutive patients with 897 ERCP procedures. Blood samples were obtained before and at different time points after the procedure. The serum concentrations of trypsinogen-1 and trypsinogen-2, PSTI and T2-AAT were determined by time-resolved immunofluorometric assays. RESULTS: ERCP-induced pancreatitis developed after 50 of the 897 ERCP procedures (5.6%). Sixty-one randomly selected ERCP patients without post-ERCP pancreatitis served as controls. Trypsinogen-1 and trypsinogen-2 showed an equally steep increase during the two first hours after ERCP in patients developing AP, but trypsinogen-1 decreased more rapidly than trypsinogen-2, which remained elevated during the 5-day study period. Serum PSTI also increased rapidly whereas T2-AAT increased more slowly peaking at 24 h. In patients developing post-ERCP pancreatitis the median concentration of trypsinogen-1 was markedly higher than in the controls already before the ERCP procedure. In the control group the concentrations of trypsinogen-1, trypsinogen-2, PSTI and T2-AAT did not change significantly. CONCLUSIONS: The rapid increase of trypsinogen-1 and trypsinogen-2 and PSTI in the early phase of AP suggests that release of pancreatic enzymes is the initial event while the delayed increase of T2-AAT may reflect that the capacity of the intrapancreatic PSTI-based inhibitory mechanism has been exhausted. 相似文献
57.
Juha Mustonen Matti Uusitupa Kalevi Selkinaho Esko Lnsimies 《Clinical physiology and functional imaging》1984,4(2):177-182
Summary. Systolic time intervals (STI) were recorded six times in 12 male students. All 72 recordings were measured twice by a physician and once by two nurses. By comparing these measurements an intra- and interobserver (= methodological) variation was obtained. For measured parameters (QS2- interval and LVET) variation was less than 2%. For calculated parameters the variation was larger, but did not reach the level of statistical significance. Methodological variation was smaller than physiologic variation. The internal consistency was almost perfect for measured parameters and only slightly worse for calculated parameters. 相似文献
58.
Thymidine kinase gene therapy for human malignant glioma, using replication-deficient retroviruses or adenoviruses 总被引:9,自引:0,他引:9
Sandmair AM Loimas S Puranen P Immonen A Kossila M Puranen M Hurskainen H Tyynelä K Turunen M Vanninen R Lehtolainen P Paljärvi L Johansson R Vapalahti M Ylä-Herttuala S 《Human gene therapy》2000,11(16):2197-2205
Herpes simplex virus thymidine kinase (HSV tk) gene therapy combined with ganciclovir (GCV) medication is a potential new method for the treatment of malignant glioma. We have used both retrovirus-packaging cells (PA317/tk) and adenoviruses (Adv/tk) for gene therapy for malignant glioma. Retrovirus-packaging cells were used for eight tumors in seven patients and adenoviruses were used for seven tumors in seven patients. As a control group, seven tumors in seven patients were transduced with lacZ marker gene 4-5 days before tumor resection. Safety and efficacy of the gene therapy were studied with clinical evaluation, blood and urine samples, MRI follow-up, and survival of the patients. Four patients with adenovirus injections had a significant increase in anti-adenovirus antibodies and two of them had a short-term fever reaction. Frequency of epileptic seizures increased in two patients. No other adverse events possibly related to gene therapy were detected. In the retrovirus group, all treated gliomas showed progression by MRI at the 3-month time point, whereas three of the seven patients treated with Adv/tk remained stable (p < 0.05). Mean survival times for retrovirus, adenovirus, and control groups were 7.4, 15.0, and 8. 3 months, respectively. The difference in the survival times between the adenovirus and retrovirus groups was significant (p < 0.012). It is concluded that HSV tk gene therapy is safe and well tolerated. On the basis of these results further trials are justified, especially with adenovirus vectors. 相似文献
59.
60.
The purpose of the study was to examine the effects of a workplace physical exercise intervention on the perceived intensity of headache and the intensity of symptoms in the neck and shoulders, as well as on the extension and flexion strength of the upper extremities. The study was a cluster randomized controlled trial. The cross-over design consisted of physical exercise intervention (15 weeks) and no-intervention (15 weeks). The subjects (n=53) were office workers (mean age 46.6 (SD 8.4)) who reported headache (n=41) symptoms in the neck (n=37) or shoulders (n=41), which had restricted their daily activities during the last 12 months. Pain symptoms were measured using the Borg CR10 scale and muscular strength with a 5RM test. Statistical analyses were based on linear mixed models. Physical exercise intervention resulted in a slight, but statistically significant, decrease in the intensity of headache and neck symptoms, as well as an increase in the extension strength of the upper extremities. The mean decrease in headache during the 5-week period was 0.64 CR10 (95% CI 0.28-1.00) (P=0.001) or 49% (95% CI 22-77), and 0.42 CR10 (95% CI 0.11-0.72) (P=0.002) or 49% (95% CI 13-85) in the intensity of neck symptoms. The mean increase in the extension strength of the upper extremities was 1.3 kg (95% CI 0.5-2.1) (P=0.001) or 4% (95% CI 1-6). The intervention had no effect on the intensity of shoulder symptoms or the flexion strength of the upper extremities. Specific exercise may be clinically important to alleviate headache and neck symptoms. 相似文献