全文获取类型
收费全文 | 10809篇 |
免费 | 784篇 |
国内免费 | 33篇 |
专业分类
耳鼻咽喉 | 138篇 |
儿科学 | 339篇 |
妇产科学 | 262篇 |
基础医学 | 1406篇 |
口腔科学 | 195篇 |
临床医学 | 1307篇 |
内科学 | 2160篇 |
皮肤病学 | 136篇 |
神经病学 | 1074篇 |
特种医学 | 521篇 |
外国民族医学 | 3篇 |
外科学 | 1745篇 |
综合类 | 103篇 |
一般理论 | 5篇 |
预防医学 | 686篇 |
眼科学 | 168篇 |
药学 | 622篇 |
中国医学 | 37篇 |
肿瘤学 | 719篇 |
出版年
2023年 | 65篇 |
2022年 | 94篇 |
2021年 | 225篇 |
2020年 | 144篇 |
2019年 | 220篇 |
2018年 | 289篇 |
2017年 | 221篇 |
2016年 | 206篇 |
2015年 | 258篇 |
2014年 | 362篇 |
2013年 | 432篇 |
2012年 | 712篇 |
2011年 | 709篇 |
2010年 | 381篇 |
2009年 | 355篇 |
2008年 | 615篇 |
2007年 | 645篇 |
2006年 | 625篇 |
2005年 | 632篇 |
2004年 | 693篇 |
2003年 | 626篇 |
2002年 | 519篇 |
2001年 | 122篇 |
2000年 | 141篇 |
1999年 | 140篇 |
1998年 | 131篇 |
1997年 | 114篇 |
1996年 | 98篇 |
1995年 | 92篇 |
1994年 | 83篇 |
1993年 | 61篇 |
1992年 | 105篇 |
1991年 | 91篇 |
1990年 | 81篇 |
1989年 | 100篇 |
1988年 | 69篇 |
1987年 | 70篇 |
1986年 | 75篇 |
1985年 | 76篇 |
1984年 | 92篇 |
1983年 | 62篇 |
1982年 | 75篇 |
1981年 | 71篇 |
1980年 | 56篇 |
1979年 | 54篇 |
1978年 | 59篇 |
1977年 | 67篇 |
1976年 | 49篇 |
1974年 | 40篇 |
1973年 | 53篇 |
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
101.
Expression of hepatitis B surface antigen with a recombinant adenovirus. 总被引:11,自引:3,他引:11 下载免费PDF全文
A R Davis B Kostek B B Mason C L Hsiao J Morin S K Dheer P P Hung 《Proceedings of the National Academy of Sciences of the United States of America》1985,82(22):7560-7564
Early region 1 of the adenovirus type 5 genome was replaced with a DNA sequence containing the gene coding for the hepatitis B surface antigen (HBsAg) flanked by the major late promoter from adenovirus 2 and processing and polyadenylylation signals from simian virus 40. In one type of hybrid virus only the adenovirus 2 major late promoter, including just 33 base pairs of the adenovirus type 2 tripartite leader, preceded the coding region of the HBsAg gene. In another, this region was preceded by both the adenovirus major late promoter and almost the entire tripartite leader. The structure of the substituted sequence in each of the recombinant viral DNAs was identical to that in the plasmids used to construct the viruses. Approximately equivalent amounts of HBsAg-specific mRNA were produced late in infection with each recombinant virus. Although HBsAg production was detected late in infection of the hybrid virus not containing the full tripartite leader sequence, its level was 1/70th of that obtained with the hybrid virus containing this sequence. One likely interpretation is that the presence of the tripartite leader at the 5' end of this mRNA is critical for the synthesis of HBsAg polypeptide in the late stage of infection. HBsAg produced upon infection with the hybrid adenoviruses was glycosylated and secreted into the culture medium as particles that were essentially indistinguishable from the 22-nm particles found in human serum. 相似文献
102.
cDNA of the immunoglobulin kappa chain of an Epstein-Barr virus-transformed human lymphoid cell line: partial sequence determination and bacterial expression. 下载免费PDF全文
J W Morin A Black M Wu S Beychok 《Proceedings of the National Academy of Sciences of the United States of America》1985,82(20):7025-7029
We report the isolation, nucleotide sequence determination, and bacterial expression of a partial cDNA for the immunoglobulin kappa chain from the Epstein-Barr virus-transformed human lymphoid cell line GM131. The cDNA, cloned in pBR322 by use of oligo(dG) X oligo(dC) tails, yields two Pst I fragments of 250 and 600 base pairs (bp). Various restriction enzyme fragments of the cDNA were subcloned in the vectors M13 mp10 and M13 mp11 for sequence analysis. As a result of instability of the 250-bp M13 subclones, the base sequence of the 250-bp Pst I fragment could not be determined. The 600-bp Pst I fragment contains coding sequences for part of the variable (V) region (residues 78-95) and all of the joining (J) (residues 96-108) and constant (C) regions (residues 109-212) and extends 148 bp into the 3' flanking region. Although the C- and 3'-flanking-region sequences are identical to germ-line sequences, the J-region sequence does not correspond to any of the five human germ-line J regions. The sequence is most similar to that of J4, with three base changes resulting in one silent mutation and two amino acid substitutions, at residues 103 (Lys----Tyr) and 106 (Ile---Met). The silent mutation appears to be the result of RNA splicing between the J and the C regions. The V-region sequence differs from published V-region germ-line sequences at several codons and from the more common amino acid sequences at two positions, residues 91 and 93. At these positions, histidine residues are found in place of the more common tyrosine and serine, respectively. None of the four amino acid substitutions observed for the GM131 kappa-chain are unique, suggesting that the changes, which most likely contribute to antigenic specificity, are compatible with antibody structure and function. The 600-bp Pst I fragment was subcloned in two prokaryotic expression vectors, pATH11 and pUC8. In both instances, a kappa-chain fusion protein detectable by immunoblotting was produced. 相似文献
103.
J J Goy V Grec M Payot A Fischer D Morin R Maendly F Stumpe U Sigwart H Sadeghi 《Archives des maladies du coeur et des vaisseaux》1985,78(9):1377-1382
Between September 1979 and December 1982, 56 St Jude Medical valvular prostheses were implanted in 54 patients over 65 years of age. Surgery consisted in simple aortic valve replacement (35 cases), simple mitral valve replacement (12 cases), double aortic and mitral valve replacement (2 cases), valve replacement and coronary artery bypass surgery (3 cases), aortic valve replacement and replacement of the ascending aorta (1 case) and mitral valve replacement and tricuspid annuloplasty (1 case). The operative mortality (within 30 days of surgery) was 3.5% (2 cases). Patients were assessed by clinical examination, ECG, chest X-ray, echocardiogram and laboratory investigations on average 19 months after surgery. There were 3 late deaths (1 endocarditis, 1 cardiac failure and 1 subdural haematoma). No cases of significant haemolysis were observed. There were no cases of thrombosis of the valve or any deaths directly related to the valve. Four patients had cerebral embolism (4.9% per patient/year). None were fatal and only 1 patient had sequellae. Clinical improvement was very significant; 96% of the patients are now in the NYHA Classes I and II whilst 80% were in Class III or IV before surgery. The cardiothoracic ratio decreased significantly from 0.56 to 0.51 (p less than 0.01). The authors conclude that elderly patients may derive great benefits from valvular cardiac surgery and that age in itself is not a contraindication to this type of surgery. The St Jude Medical prosthesis is an excellent prosthesis but thromboembolism remains a major problem as with other mechanical prostheses. Anticoagulation for life is essential. 相似文献
104.
A "closed bath" cremaster muscle preparation is described which permits the administration of vasoactive materials to the microvasculature via intraarterial injection and topical suffusion. The technique is evaluated in spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats by comparing arteriolar responses to intraarterial and topically suffused arginine vasopressin. The preparation utilizes a thermostatically heated brass suffusion chamber overlying the cremaster. The chamber is closed with a glass coverslip. Experimental materials are presented to the microvessels via intraarterial injection or suffusion through the chamber. The coverglass permits high optical resolution with both routes of administration. Following vasopressin administration, changes in arteriolar diameter were continuously monitored by image-shearing techniques or variable-resistance calipers. The responses were analyzed by comparing both the peak 5-sec vasoconstriction and a 60-sec integrated response. Intraarterial and topical suffusion of vasopressin (1.25 X 10(-10)-3.75 X 10(-7) M) caused dose-dependent vasoconstriction among 23-microns arterioles. Compared to the WKY, vasoconstriction was greater in the SHR when vasopressin was administered intraarterially. A similar strain difference was not observed with topical suffusion. The dose-response curves with intraarterial vasopressin were shifted approximately 100-fold in concentration to the right relative to those with topically suffused vasopressin. The "closed bath" cremaster muscle preparation described has several distinct advantages: (1) it permits introduction of different vasoactive materials in the most physiological manner in the same animal, and (2) it maintains high optical resolution and clarity for critical observation of the smallest vessels, even with suffusion. 相似文献
105.
Morin AM Bezler T Eberhart LH Mayer R Schreiber MN Kilian J Georgieff M 《Der Anaesthesist》1999,48(1):19-25
Background: Droperidol even in low doses such as 0,5?mg to 1,25?mg can increase postoperative anxiety and state of tension. The aim of this study was to determine whether these side effects occur frequently following low-dose droperidol and to see whether these are dose related. Methods: 184 female in- and outpatients ASA grade 1 and 2 undergoing gynaecological laparoscopy were recruited to this prospective, double-blind study. General anaesthesia was standardized (induction with thiopentone, fentanyl 2?µg/kg and vecuronium 0,1?mg/kg, tracheal intubation, maintainance with enflurane in N2O/O2). Patients were randomly allocated to receive saline (n=45), 0,625?mg (n=46), 1,25?mg (n=47) or 2,5?mg (n=46) droperidol i.v. 10 minutes before the end of surgery. 1, 3, 6, and 24 hours postoperatively, the patients’ anxiety, state of tension and overall mood was evaluated using two psychological questionnaires which had been tested for the perioperative period (Erlanger anxiety and tension-scale / BSKE-EWL-test). Sedation was evaluated by the staff of the recovery room. In addition, postoperative nausea and vomiting (PONV) was assessed using a 100?mm visual analogue scale and by counting the episodes of retching or vomiting. PONV was then rated over the whole observation period as none, mild, moderate or severe using a fixed scoring algorithm. Statistical analysis was performed using the ANOVA and the chi2-test. Results: The patients did not differ with regard to biometric data, duration of surgery and anaesthesia. The postoperative scores for anxiety, state of tension and overall mood were not different between the groups at any observation time (Fig.?1: anxiety and tension: P=0,5687; figure 2: overall mood: P=0,0647). Quality of sleep in the first night after surgery was the same in all groups (Table?2 and 3). Sedation was not significantly different (Table?4; P=0,0704). Furthermore, duration of stay in the recovery room did not differ (P=0,4353). On the other hand, three patients from the 2,5?mg droperidol group had to stay unexpectedly on the ward overnight, because they had been too much sedated to be discharged at home. This was not the case with any patient from the other groups. Compared to placebo, PONV over the whole 24?h observation period was significantly reduced by droperidol (Fig.?3; P=0,0338): completely free from PONV: placebo: 41,3%, 0,625?mg droperidol: 67,4%, 1,25?mg droperidol: 53,2%, 2,5?mg droperidol: 71,7%. Also the severity of PONV was reduced. Conclusion: In gynaecological laparoscopy under general anaesthesia with tracheal intubation, we recommend droperidol 0,625?mg in the prevention of PONV, as it reduces PONV as well as 2,5?mg with no severe sedation in this dosage. Psychological side effects did not occur more frequently after droperidol compared to placebo in any of the investigated dosages. 相似文献
106.
Percutaneous Imaging–Guided Radiofrequency Ablation in Patients With Colorectal Pulmonary Metastases: 1-Year Follow-Up 总被引:3,自引:2,他引:3
Steinke K Glenn D King J Clark W Zhao J Clingan P Morris DL 《Annals of surgical oncology》2004,11(2):207-212
Background: We assessed the safety and evidence of efficacy of radiofrequency ablation (RFA) for colorectal lung metastases with follow-up to 1 year.Methods: Twenty-three patients had percutaneous RFA for 52 colorectal pulmonary metastases under fluoro-computed tomography (CT). Patients received intravenous conscious sedation and local analgesia with routine hospitalization and monitoring for 24 hours after RFA. Patients had CT scanning at 1 month and then every 3 months, with serum carcinoembryonic antigen assessment monthly and every 3 months.Results: All ablations were technically successful. Tumor diameter ranged from .3 to 4.2 cm. Pneumothorax occurred in 43% (10 of 23) of patients. Six patients required intercostal chest drain placement. Six patients had a second RFA, four for new lesions and two for re-treatment of a previously treated lesion. The median admission was 2.0 days (range, 1–9 days). The median follow-up was 428 days (range, 173–829 days); data are reported to 1 year in this article. Five patients died at 5, 6, 8, 8, and 12 months after RFA from extrapulmonary (n = 1) or widespread (n = 4) disease. One patient developed a malignant pleural effusion at 6 months after RFA. Cavitation was seen in nine treated lesions (17%); all resolved with scar tissue contraction by 12 months. Eighteen patients with CT scan follow-up at 1 year have 40 lesions classified as disappeared (n = 17), decreased (n = 5), stable/same size (n = 4), or increased (n = 14).Conclusions: Percutaneous imaging–guided RFA of multiple colorectal pulmonary metastases is a minimally invasive treatment option with modest morbidity. A significant proportion of patients show good evidence of successful local control at 1 year. 相似文献
107.
108.
Savdie R Horvath LG Benito RP Rasiah KK Haynes AM Chatfield M Stricker PD Turner JJ Delprado W Henshall SM Sutherland RL Kench JG 《BJU international》2012,109(12):1794-1800
Study Type – Prognosis (case series) Level of Evidence 4 What's known on the subject? and What does the study add? Only 30–35% of patients with positive surgical margins after radical prostatectomy develop recurrent disease. Adjuvant radiotherapy reduces the rate of biochemical relapse or metastasis and improves overall survival after radical prostatectomy. Various pathological factors, such as location and extent of positive margins, have been proposed as possible prognostic factors in men with margin‐positive prostate cancer, however, the recent International Society of Urological Pathology consensus meeting in Boston noted that there is limited data on the significance of Gleason grade of the carcinoma at a positive margin. The present study shows that the presence of high grade prostate cancer, i.e. Gleason pattern 4 or 5, at a positive surgical margin is an independent predictor of biochemical recurrence after radical prostatectomy. Moreover, patients with lower grade carcinoma at the margin have a similar prognosis to men with negative margins. Hence, assessment of Gleason grade at the site of positive margin may aid optimal selection of patients for adjuvant radiotherapy.
OBJECTIVE
- ? To establish predictors of biochemical recurrence by analysing the pathological characteristics of positive surgical margins (PSMs), including Gleason grade of the carcinoma at the involved margin.
PATIENTS AND METHODS
- ? Clinicopathological and outcome data on 940 patients who underwent radical prostatectomy (RP) between 1997 and 2003 were collected.
- ? Of these, 285 (30.3%) patients with PSMs were identified for pathological review, including assessment of location of margin, linear extent, number of PSMs, plane of margin and Gleason grade (3 vs 4 or 5) at the margin.
RESULTS
- ? At a median follow‐up of 82 months, the biochemical recurrence rate of the PSM cohort was 29%.
- ? On univariate analysis, the presence of Gleason grade 4 or 5 at the margin (34.4% of cases) was significantly associated with biochemical recurrence (hazard ratio [HR] 2.80, 95% confidence interval [CI]= 1.82–4.32, P < 0.001) compared with the presence of Gleason grade 3.
- ? Linear extent of margin involvement was also associated with recurrence (P= 0.009).
- ? Single vs multiple margin involvement, location, and plane of the involved margin were not significant predictors of recurrence.
- ? On multivariate analysis, Gleason grade 4 or 5 at the margin remained an independent predictor of recurrence (HR 2.14, 95% CI = 1.29–4.03, P= 0.003).
CONCLUSION
- ? The Gleason grade at the site of a PSM identifies patients at increased risk of biochemical recurrence and should aid stratification of patients for adjuvant radiation therapy.
109.
McGuire BB Helfand BT Loeb S Hu Q O'Brien D Cooper P Yang X Catalona WJ 《BJU international》2012,109(12):1764-1769
Study Type – Therapy (case series) Level of Evidence 4 What's known on the subject? and What does the study add? High‐grade prostate cancers are associated with poor disease‐specific outcomes. A proportion of these tumours produce little PSA. This study demonstrates that among Gleason 8–10 prostate cancers, some of the worst survival outcomes are associated with the lowest PSA levels.
OBJECTIVE
- ? To assess outcomes of patients with Gleason score 8–10 prostate cancer (CaP) with a low (≤2.5 ng/mL) vs higher preoperative serum PSA levels.
PATIENTS AND METHODS
- ? From 1983 to 2003, 5544 patients underwent open radical prostatectomy, of whom 354 had a Gleason 8–10 tumour in the prostatectomy specimen.
- ? Patients were stratified according to preoperative PSA level into four strata: ≤2.5 ng/mL (n= 31), 2.6–4 ng/mL (n= 31), 4.1–10 ng/mL (n= 174), and >10 ng/mL (n= 118).
- ? We compared biochemical progression‐free survival (PFS), metastasis‐free survival (MFS), and cancer‐specific survival (CSS) as a function of preoperative PSA level.
RESULTS
- ? Patients with PSA level ≤2.5 ng/mL were more likely to have seminal vesicle invasion (P= 0.003).
- ? On Kaplan–Meier survival analysis, patients with a PSA level ≤2.5 ng/mL had proportionately worse outcomes than their counterparts with higher PSA levels.
- ? The 7‐year PFS in the PSA ≤2.5 ng/mL stratum was lower than those of the PSA 2.6–4 ng/mL and 4–10 ng/mL strata (36% vs 50 and 42%, respectively); however, the lowest 7‐year PFS was found in those with a PSA level >10 ng/mL (32%, P= 0.02).
- ? Gleason score 8–10 tumours with a PSA level ≤2.5 ng/mL also tended to have the lowest 7‐year MFS (75, 93, 89 and 92% for PSA level ≤2.5, 2.6–4, 4.1–10 and >10 ng/mL, respectively, P= 0.2) and CSS (81, 100, 94 and 90% for PSA level ≤2.5, 2.6–4, 4.1–10 and >10 ng/mL, respectively, P= 0.3), although these differences were not statistically significant.
- ? In the subset with palpable disease, Gleason grade 8–10 disease with PSA level ≤2.5 ng/mL also was associated with a worse prognosis.
CONCLUSIONS
- ? In patients with Gleason grade 8–10 disease, a proportion of these tumours are so poorly differentiated that they produce relatively little PSA.
- ? Patients with high‐grade, low‐PSA tumours had less favourable outcomes than many of those with higher PSA levels.
110.