全文获取类型
收费全文 | 18925篇 |
免费 | 2375篇 |
国内免费 | 31篇 |
专业分类
耳鼻咽喉 | 129篇 |
儿科学 | 763篇 |
妇产科学 | 371篇 |
基础医学 | 2824篇 |
口腔科学 | 519篇 |
临床医学 | 2023篇 |
内科学 | 4307篇 |
皮肤病学 | 166篇 |
神经病学 | 1459篇 |
特种医学 | 705篇 |
外科学 | 2797篇 |
综合类 | 456篇 |
一般理论 | 16篇 |
预防医学 | 1871篇 |
眼科学 | 237篇 |
药学 | 1623篇 |
中国医学 | 10篇 |
肿瘤学 | 1055篇 |
出版年
2022年 | 147篇 |
2021年 | 274篇 |
2020年 | 199篇 |
2019年 | 282篇 |
2018年 | 300篇 |
2017年 | 230篇 |
2016年 | 227篇 |
2015年 | 281篇 |
2014年 | 442篇 |
2013年 | 576篇 |
2012年 | 917篇 |
2011年 | 902篇 |
2010年 | 486篇 |
2009年 | 456篇 |
2008年 | 820篇 |
2007年 | 921篇 |
2006年 | 840篇 |
2005年 | 894篇 |
2004年 | 820篇 |
2003年 | 843篇 |
2002年 | 805篇 |
2001年 | 623篇 |
2000年 | 659篇 |
1999年 | 582篇 |
1998年 | 280篇 |
1997年 | 229篇 |
1996年 | 239篇 |
1995年 | 204篇 |
1994年 | 229篇 |
1993年 | 203篇 |
1992年 | 461篇 |
1991年 | 424篇 |
1990年 | 425篇 |
1989年 | 362篇 |
1988年 | 345篇 |
1987年 | 317篇 |
1986年 | 316篇 |
1985年 | 342篇 |
1984年 | 267篇 |
1983年 | 208篇 |
1982年 | 167篇 |
1981年 | 170篇 |
1979年 | 236篇 |
1978年 | 178篇 |
1977年 | 187篇 |
1976年 | 144篇 |
1975年 | 166篇 |
1974年 | 205篇 |
1973年 | 207篇 |
1972年 | 136篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
William R. C. Knight Cara R. Baker Nyree Griffin Wahyu Wulaningsih Mark Kelly Andrew R. Davies James A. Gossage 《British journal of cancer》2021,124(10):1653
Background A high Mandard score implies a non-response to chemotherapy in oesophageal adenocarcinoma. However, some patients exhibit tumour volume reduction and a nodal response despite a high score. This study examines survival and recurrence patterns in these patients.Methods Clinicopathological factors were analysed using multivariable Cox regression assessing time to death and recurrence. Computed tomography-estimated tumour volume change was examined in a subgroup of consecutive patients.Results Five hundred and fifty-five patients were included. Median survival was 55 months (Mandard 1–3) and 21 months (Mandard 4 and 5). In the Mandard 4 and 5 group (332 patients), comparison between complete nodal responders and persistent nodal disease showed improved survival (90 vs 18 months), recurrence rates (locoregional 14.75 vs 28.74%, systemic 24.59 vs 48.42%) and circumferential resection margin positivity (22.95 vs 68.11%). Complete nodal response independently predicted improved survival (hazard ratio 0.34 (0.16–0.74). Post-chemotherapy tumour volume reduction was greater in patients with a complete nodal response (−16.3 vs −7.7 cm3, p = 0.033) with no significant difference between Mandard groups.Conclusion Patients with a complete nodal response to chemotherapy have significantly improved outcomes despite a poor Mandard score. High Mandard score does not correspond with a non-response to chemotherapy in all cases and patients with nodal downstaging may still benefit from adjuvant chemotherapy.Subject terms: Oesophageal cancer, Surgical oncology 相似文献
2.
Jim Zhong Michael Gallagher Chris Hounslow Gareth Iball Tze Wah 《Diagnostic and interventional radiology (Ankara, Turkey)》2021,27(2):244
PURPOSEWe aimed to evaluate the effect on the radiation dose to the patient by reducing the tube current during the placement of the ablation needles (reduced dose group) compared with the patient doses delivered when scanning at the standard fully diagnostic level (full dose group) in computed tomography (CT)-guided percutaneous cryoablation.METHODSWe conducted a retrospective study of 103 patients undergoing cryoablation in a tertiary cancer center. Overall, 62 patients were scanned with standard exposure parameters (full dose group) set on a 64-slice multidetector CT scanner, while 41 patients were scanned on a reduced dose protocol. Dose levels were retrieved from the hospital picture and archiving communication system including the volumetric CT dose index (CTDIvol), total dose length product (DLP), length of cryoablation procedure, number of cryoablation needles and patient size. Wilcoxon Mann-Whitney (rank-sum) tests were used to compare the median DLP, CTDIvol and skin dose between the two groups.RESULTSMedian total DLP for the full dose group was 6025 mGy·cm (1909–13353 mGy·cm) compared with 3391 mGy·cm (1683–6820 mGy·cm) for the reduced dose group. The reduced dose group had a 44% reduction in total DLP and 42% reduction in total CTDIvol (p < 0.001). The estimated skin doses were 384 mGy for the full dose group and 224 mGy for the reduced dose group (42% reduction) (p < 0.001). At 12-month follow-up, the technical success for the full dose (n=62) was 97% with 2 patients requiring a further cryoablation treatment for residual tumor. The technical success for the reduced dose group (n=41) was 100%.CONCLUSIONCT dose reduction technique during image-guided cryoablation treatment of renal tumors can achieve significant radiation dose reduction whilst maintaining sufficient image quality.Renal cell carcinoma is the most common kidney cancer and has a rising incidence (1–4), with obesity and smoking being major risk factors (5–8).Image-guided ablation offers a more minimally invasive option compared with surgery and the current evidence base shows that it is a safe and effective treatment for T1a tumors, with a low rate of complications (9–11). The major advantage of cryoablation over other modalities is the ability to accurately visualize the iceball and therefore zone of ablation on intraprocedural imaging, either with computed tomography (CT) or magnetic resonance imaging (MRI) (12, 13). However, renal cryoablation involves the placement of more ablation probes and can have almost three times the radiation exposure compared with CT-guided radiofrequency ablation procedures (14).In addition to this substantial radiation dose per cryoablation, estimated to be between 32 and 39.7 mSv, the follow-up CT imaging will also add to the total radiation burden (15, 16). Whilst this level of radiation dose and associated stochastic risk may be a lesser concern in the older patients, greater consideration needs to be given to younger patients (<50 years old) and in patients requiring lifelong follow-up imaging, in particular those with hereditary diseases such as Von Hippel-Lindau syndrome (15). To our knowledge, the potential for reducing radiation dose for cryoablation patients.The principle aim of this study was to evaluate the effect on the radiation dose to the patient by reducing the tube current during the placement of the ablation needles (reduced dose group) compared with the patient doses delivered when scanning at the standard fully diagnostic level (full dose group) in CT-guided percutaneous cryoablation. 相似文献
3.
4.
5.
Dr. Arthur A. Dunk MRCP Natasha Kyprianou MSc Peter Davies PhD Howard C. Thomas PhD FRCP 《Digestive diseases and sciences》1988,33(4):472-476
Castrated or sham-operated male athymic mice were inoculated with cells from the human hepatocellular carcinoma cell line PLC/PRF/5. There were no significant differences between the two groups with respect to the number of animals developing tumors, the time to tumor development, or the subsequent rate of increase in either tumor base area or mouse serum alpha-fetoprotein concentration. Androgen receptors were assayed in nuclei obtained from three separate liver cancer cell lines and from normal adult human liver. Similar concentrations, ranging from 235 to 550 fmol/mg DNA, of nuclear androgen receptors were detected in all tissues. Low percentages of androgen receptors were retained on DNA-cellulose. Although the presence of receptors implies the potential for metabolic effects of androgens in normal and malignant liver, our in vivostudies suggest that castration does not alter significantly the growth of liver cancer xenografts in athymic mice. 相似文献
6.
G E Davies A V Thompson Z Niewola G E Burrows E L Teasdale D J Bird D A Phillips 《Occupational and environmental medicine》1983,40(4):442-449
Twenty four volunteers who had been allergic to laboratory animals for some years were examined by means of a questionnaire paying particular attention to symptoms associated with rats and by serological and skin tests with extracts of rat urine (retrospective study). Nasal and eye symptoms were reported by 21 and 16 individuals respectively: 13 had asthma. Positive skin tests and high levels of specific IgE antibody to rat urine extract were found in 17 of the more severely affected individuals and this group included 12 of those with asthma. Latent periods of work with animals before symptoms appeared varied from 0.5 to 12 years. Also 148 individuals were studied during their first year of work with animals (prospective study). Symptoms developing during the year were reported by 15%, asthma by 2%. IgE antibody levels to rat urine were raised in 40% of affected and 6% of the unaffected individuals but there was no significant correlation between symptoms and either antibody levels or positive skin tests. Allergic symptoms developing during the first year of postemployment were, on the whole, much milder than those seen in the retrospective study. A tentative conclusion is that most individuals who become allergic to laboratory animals develop the condition in a mild form during their first year of employment but it appears probable that atopic individuals, although having an equal chance of developing allergy as compared with non-atopic individuals, may eventually progress to a more severe form of the disease. 相似文献
7.
The bulk of research into drug driving in Australia has been undertaken from a road safety orientation where drug driving is viewed within the broader context of road safety and driver behaviour. Such a specific focus precludes the broader behavioural, contextual and cultural issues associated with substance use. This study aimed to address this issue by focusing on drug driving behaviour within the context of illicit substance use. A series of focused interviews were conducted with 211 illicit drug users from urban and regional centres. A consistent theme identified in the interviews was that drug driving was not necessarily viewed as risky behaviour but rather as an outcome of illicit substance use. Further, some interviewees saw their drug use as enhancing their driving skills and frequently the motor vehicle was viewed as a safe place to use. Overall there was agreement among interviewees that the likelihood of being apprehended for drug driving by police was minimal; this perception was reinforced by past experience. The lack of concern for detection of drug driving behaviour suggests that research should continue into the development and implementation of enforcement programs and roadside detection. 相似文献
8.
A cohort of 1163 pregnant women in two small towns in South Wales, UK, was identified and followed until the children born to them were five years of age. Growth in these children is described and a number of determinants identified. Social-class differences were very small at birth but differences in height became clear by the age of two years and in head circumference before this. In height the differences were largely accounted for by greater growth in social class I, but there was a gradient in head circumference throughout all the social classes. The social class effects gradually increased as the children became older. Parity of the mothers had a small effect on size at birth but age of the mother had no effect once parity was allowed for. Data on illnesses in the children were collected but no effect on growth could be detected. By far the most important determinant of growth which could be controlled is maternal smoking. About 40% of the women smoked, about 17% heavily (15 or more cigarettes per day) and the prevalence of smoking altered little during pregnancy. There was a graded effect of smoking on growth up to a 9% deficit in birth-weight, a 2% deficit in length at birth and a 1.5% deficit in head circumference in the babies born to the mothers who smoked most heavily (25 or more cigarettes per day) compared with non-smokers. There effects decreased with age but there were still residual effects at age five years. 相似文献
9.
Changes in the biophysical properties and ultrastructure of lungs, and intrapulmonary fibrin deposition in experimental acute pancreatitis
下载免费PDF全文
![点击此处可从《Gut》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Using an experimental model of acute pancreatitis in the rat, we have studied changes in the biophysical properties of lungs and intrapulmonary fibrin deposition in this condition. Acute pancreatitis is associated with a significant decrease in pulmonary compliance (p less than 0.01) and a significant increase in lung weight (p less than 0.01) compared with a control sham operation group. These changes are associated with a 24% increase in intrapulmonary 125I fibrinogen deposition (p less than 0.01), and an 18% increase in 125I fibrinogen deposition per gram of lung tissue (p less than 0.05) in acute pancreatitis, compared with a control sham operation group. The increased fibrinogen deposition is abolished by treatment with low dose heparin. Using the same animal model changes in pulmonary ultrastructure are shown using scanning electron microscopy. The results indicate that pulmonary abnormalities are associated with intrapulmonary fibrin deposition in experimental acute pancreatitis and these findings may be relevant to the well described respiratory complications of the condition in man. 相似文献
10.
Successful and unsuccessful coronary thrombolysis 总被引:1,自引:0,他引:1
M J Davies 《British heart journal》1989,61(5):381-384