全文获取类型
收费全文 | 25217篇 |
免费 | 2213篇 |
国内免费 | 80篇 |
专业分类
耳鼻咽喉 | 233篇 |
儿科学 | 510篇 |
妇产科学 | 352篇 |
基础医学 | 3492篇 |
口腔科学 | 763篇 |
临床医学 | 2730篇 |
内科学 | 5076篇 |
皮肤病学 | 362篇 |
神经病学 | 2253篇 |
特种医学 | 1272篇 |
外科学 | 3871篇 |
综合类 | 406篇 |
一般理论 | 22篇 |
预防医学 | 1963篇 |
眼科学 | 684篇 |
药学 | 1677篇 |
中国医学 | 19篇 |
肿瘤学 | 1825篇 |
出版年
2023年 | 145篇 |
2022年 | 285篇 |
2021年 | 595篇 |
2020年 | 361篇 |
2019年 | 505篇 |
2018年 | 577篇 |
2017年 | 461篇 |
2016年 | 510篇 |
2015年 | 632篇 |
2014年 | 804篇 |
2013年 | 1042篇 |
2012年 | 1668篇 |
2011年 | 1712篇 |
2010年 | 998篇 |
2009年 | 937篇 |
2008年 | 1432篇 |
2007年 | 1529篇 |
2006年 | 1360篇 |
2005年 | 1326篇 |
2004年 | 1195篇 |
2003年 | 1139篇 |
2002年 | 949篇 |
2001年 | 532篇 |
2000年 | 547篇 |
1999年 | 458篇 |
1998年 | 237篇 |
1997年 | 214篇 |
1996年 | 173篇 |
1995年 | 159篇 |
1994年 | 159篇 |
1993年 | 146篇 |
1992年 | 308篇 |
1991年 | 291篇 |
1990年 | 268篇 |
1989年 | 251篇 |
1988年 | 244篇 |
1987年 | 249篇 |
1986年 | 207篇 |
1985年 | 239篇 |
1984年 | 207篇 |
1983年 | 164篇 |
1982年 | 136篇 |
1981年 | 119篇 |
1979年 | 200篇 |
1978年 | 130篇 |
1977年 | 134篇 |
1976年 | 107篇 |
1973年 | 132篇 |
1972年 | 116篇 |
1971年 | 116篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
M. Sivakumaran Stephen J. Richards Kaye M. Hunt rew J. Steed A. Geraldine Bynoe Mary M. Morgan Roger Pyrah Bryon E. Roberts Colin Stephen Scott 《British journal of haematology》1991,78(3):368-377
Phenotypic characteristics, and correlations between the expression of membrane NK-associated (NKa) determinants (CD11b, CD16, CD56 and CD57) and T cell receptor (TCR) genotypic patterns, were examined in 25 patients with persistent (greater than 6 months) expansions of CD3+WT31+NKa+ (CD8+ and CD8dim+) lymphocytes. These studies showed that distinct NKa phenotypic profiles were restricted to cases with rearranged TCR configurations and that clonal CD3+NKa+ components could be predicted in most cases by assessing relationships between membrane CD16 and CD56 expression. For all normal NKa subpopulations, there was a high correlation (P less than 0.0001; n = 31) between the expression of these two membrane determinants. Markedly increased CD16 expression by CD3+NKa+ cells, in relation to CD56 (i.e. a high CD16:CD56 ratio), was found exclusively in cases with rearranged TCR (13/16 cases); 2/3 of the remaining cases showing significantly reduced CD16:CD56 ratios and high (greater than 2.0) CD3+CD56+ absolute numbers. In contrast, 7/9 of the germline TCR cases had a normal CD16:CD56 ratio and 2/9 a decreased ratio with low (less than 1.0) CD3+CD56+ absolute numbers. A high ratio of CD16:CD56 expression by CD3+NKa+ lymphocytes was therefore informative for 82% of TCR rearrangements in this series; and analysis of CD16 and CD56 expression was predictive for germline and rearranged TCR configurations in 24/25 persistent CD3+NKa+ expansions. 相似文献
102.
The retinal pigment epithelium (RPE) plays several important roles in the continual support and renewal of photoreceptor outer segments. In the present study, we have demonstrated that RPE cells contain a low molecular weight protein with a high capacity for zinc binding that is dependent on available sulfhydryl groups. This protein is inducible by a 24 hour incubation of cultured RPE in medium supplemented with zinc, cadmium, or dexamethasone. The induction of this protein is correlated with an increased capacity for zinc-65 uptake into cultured RPE. Analysis with a cDNA probe specific for the human metallothionein II gene corroborated the existence and induction of metallothionein gene products in RPE cells. Based on these properties, we have identified this protein as metallothionein. The induction of metallothionein likely has a critical influence on the zinc economy of the RPE. 相似文献
103.
Intensive versus standard blood glucose awareness training (BGAT) with insulin-dependent diabetes: mechanisms and ancillary effects 总被引:1,自引:0,他引:1
D J Cox L Gonder-Frederick D Julian P Cryer J H Lee F E Richards W Clarke 《Psychosomatic medicine》1991,53(4):453-462
Insulin-dependent diabetes mellitus (IDDM) patients make critical daily self-care decisions on the basis of what they estimate their blood glucose (BG) levels to be. This study: a) replicated efficacy of Standard Blood Glucose Awareness Training (BGAT), b) evaluated the relative efficacy of an Intensive Blood Glucose Awareness Training (BGAT) to enhance patient accuracy of BG estimation, and c) evaluated the mechanisms and ancillary effects of BGAT. Thirty-nine subjects were randomly assigned to one of three groups. Compared with Control, both Standard and Intensive BGAT improved accuracy (p less than 0.001). Intensive BGAT post-treatment accuracy relative to Standard BGAT did not reach statistical significance (p = 0.177). Greater improvement in accuracy was associated with poorer pretreatment accuracy. Only Intensive BGAT improved metabolic control (glycosylated hemoglobin), and this improvement was associated with poorer pretreatment control. The effects of BGAT were highly specific, affecting only accuracy and metabolic control, and not affecting fear of hypoglycemia, diabetes knowledge, of frequency of blood glucose monitoring. 相似文献
104.
R Benoit D Dorval J Loulergue Y Bacq J M Oliver A Audurier E H Metman 《Gastroentérologie clinique et biologique》1992,16(11):860-864
From May 1989 to January 1991, 20 patients were investigated for antibiotic-associated acute diarrhea. Colonoscopy or rectosigmoidoscopy was performed in each patient. Cultures of colonic mucosal biopsies were carried out using conventional culture grounds (cystine-lactose-electrolyte-deficient). The aim of this study was to investigate the role of a gram negative bacillus: Klebsiella oxytoca. Among the 20 patients with antibiotic-associated acute diarrhea, 11 had bloody and mucus diarrhea and colitis ranging from a right-sided hemorrhagic to diffuse acute ulcerative or erosive colitis, 7 had a grossly normal colonic appearance, while 2 had mucus diarrhea and pseudomembranous colitis. Of colonic biopsies cultures obtained from 36 control patients, 15 had a normal colonic appearance, 15 had ulcerative or crohn's colitis, 6 had well-tolerated amoxicillin therapy. Klebsiella oxytoca was never found in the 36 control patients; Klebsiella oxytoca was noted among 8/11 patients with mucus-discharging and bloody diarrhea. These results suggest that antibiotic-associated, non pseudomembranous colitis is frequently associated with Klebsiella oxytoca infection, which may be the cause of this type of colitis. 相似文献
105.
M A López Cara P J Tárraga López M Cerdán Oliver J M Oca?a López A Celada Rodríguez J Solera Albero M A Palomino Medina 《Revista española de enfermedades digestivas》2006,98(6):449-459
OBJECTIVE: To Determine the incidence of constipation in Albacete province and its relation with diet and lifestyle. PATIENTS AND METHODS: Cross-sectional population survey. We studied 414 participants over 50 years of age in Albacete province. 445 persons over 50 years of age were included in the study. All participants were selected by systematic random sampling; 414 participants filled in the questionnaire correctly. Main measures: age, weight and height, marital status, level of education and occupation; presence of a disease, number of sleep hours a day, physical exercise, smoking, alcohol intake, drug intake (anti-inflammatories and laxatives); bowel habit, diet, meal frequency and place; food intake frequency per week, daily intake of water, coffee, tea and herbal beverages; vitamin and fiber supplements; presence of cancer in the family. RESULTS: 56.9% of participants were women. Mean age 67.07 years. In Albacete province, 4.4% of the population over 50 years have a bowel habit consistent with constipation. Most participants had three meals a day (breakfast, lunch, and supper), while 50% had another meal in the morning or afternoon. These meals took place, habitually, in the domicile. There was a preponderance in daily intake of the following foods: milk (83.7%), bread (95.1%), vegetables (68.8%), fruit (91.8%), and virgin olive oil (96.6%). Fish was eaten every one to two days, and pulses and meat every three to six days. 44.4% of participants drank one to two liters of water a day. Only 3.9% of participants took some supplement; 35% of participants were on a diet. It was observed that 97.7% of participants with more than three defecations a week had a high intake of virgin olive oil; 65.7% of participants did some physical exercise customarily; 70.2% of participants were non-smokers, 10.2% were smokers, and 18.4% were ex-smokers. With regard to alcohol, the percentage of drinkers was 35.1%. The main class of medications taken by participants was NSAIDs - 14.5%; 79.7% took neither NSAIDs nor laxatives. Only 2.7% of participants took laxatives regularly. CONCLUSIONS: Most participants had relatively healthy eating habits. 相似文献
106.
Imaging of acute mesenteric ischemia using multidetector CT and CT angiography in a porcine model 总被引:3,自引:0,他引:3
David E. Rosow M.D. Dushyant Sahani M.D. Oliver Strobel M.D. Sanjeeva Kalva M.D. Mari Mino-Kenudson M.D. Nagaraj S. Holalkere M.D. Guido Alsfasser M.D. Sanjay Saini M.D. Susanna I. Lee M.D. Peter R. Mueller M.D. Carlos Fernándezdel Castillo M.D. Andrew L. Warshaw M.D. Sarah P. Thayer M.D. Ph.D. 《Journal of gastrointestinal surgery》2005,9(9):1262-1275
Acute mesenteric ischemia, a frequently lethal disease, requires prompt diagnosis and intervention for favorable clinical
outcomes. This goal remains elusive due, in part, to lack of a noninvasive and accurate imaging study. Traditional angiography
is the diagnostic gold standard but is invasive and costly. Computed tomography (CT) is readily available and noninvasive
but has shown variable success in diagnosing this disease. The faster scanning time of multidetector row CT (M.D.CT) greatly
facilitates the use of CT angiography (CTA) in the clinical setting. We sought to determine whether M.D.CT-CTA could accurately
demonstrate vascular anatomy and capture the earliest stages of mesenteric ischemia in a porcine model. Pigs underwent embolization
of branches of the superior mesenteric artery, then imaging by M.D.CT-CTA with three-dimensional reconstruction protocols.
After scanning, diseased bowel segments were surgically resected and pathologically examined. Multidetector row CT and CT
angiography reliably defined normal and occluded mesenteric vessels in the pig. It detected early changes of ischemia including
poor arterial enhancement and venous dilatation, which were seen in all ischemic animals. The radiographic findingsd—compared
with pathologic diagnosesd—predicted ischemia, with a positive predictive value of 92%. These results indicate that M.D.CT-CTA
holds great promise for the early detection necessary for successful treatment of acute mesenteric ischemia.
Presented at the Forty-Sixth Annual Meeting of The Society for Surgery of the Alimentary Tract, Chicago, Illinois, May 14–18,
2005 (oral presentation).
Supported by the Karin Grunebaum Research Fellowship, Harvard Medical School (D.E.R.), the German Research Fellowship, German
Research Foundation STR 690/1-1 (O.S.), and the Phillip H. Meyers Grant from the Society of Gastrointestinal Radiologists
(S.P.T.). 相似文献
107.
Abnormalities of thirst regulation in patients with chronic renal failure on hemodialysis. 总被引:3,自引:0,他引:3
A Martinez-Vea C García J Gaya F Rivera J A Oliver 《American journal of nephrology》1992,12(1-2):73-79
To determine whether thirst mechanisms are altered in nondiabetic patients with chronic renal failure on hemodialysis, 4 patients with an average weight gain between dialysis sessions of more than 5% of dry body weight (group I), 5 patients with less than 3% weight gain (group II), and a group of 6 healthy subjects (group III) were submitted to infusion of hypertonic saline. After infusion the subjects had free access to water. Thirst was evaluated by visual analogue rating scales. Despite similar increments of effective plasma osmolality during saline infusion, patients of group I were thirstier than groups II and III (p less than 0.005 and p less than 0.01, respectively). Changes in thirst ratings were similar in groups II and III. Osmotic thresholds for thirst onset were similar in groups II and III (288.9 +/- 8.5 and 289.8 +/- 3.4 mosm/kg, respectively), but lower in group I (277.6 +/- 7.6 mosm/kg). Nevertheless, great variations were observed in the latter group. Thus, 2 patients showed thresholds for thirst within the normal range, whereas the others had low osmolar thresholds for thirst and baseline plasma osmolalities and high basal thirst scores. During the drinking period, the patients of group I drank more (14.2 +/- 2.8 ml/kg) than those of groups II (5.3 +/- 1.6 ml/kg; p less than 0.02) and III (10.2 +/- 1.6 ml/kg; n.s.) The plasma levels of angiotensin II in uremic patients were higher than in healthy subjects, although there were no differences between groups I and II and no correlation between basal angiotensin II levels and the interdialytic weight gain.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
108.
W. M. Gregory P. Smith M. A. Richards C. J. Twelves R. K. Knight R. D. Rubens 《British journal of cancer》1993,68(5):988-995
The outcome for 758 consecutive patients who had received one or more chemotherapy regimens for recurrent or metastatic breast cancer is presented. The response rate following first line treatment was 34%. Median duration of response was 7.8 months, median time to progression was 3.7 months and median survival was 7.9 months. The only factor predicting for response, of factors recorded at presentation and at initiation of chemotherapy, was the use of anthracycline based regimens, though this may reflect the patient selection policy. Initial disease free interval, presence of liver metastases and use of anthracyclines were significantly related to time to progression. Several factors related to survival following first chemotherapy, but anthracycline usage showed only a very weak correlation. One third of patients (249/758) received two or more chemotherapy regimens. The response rate (16%) and median time to progression (2.3 months) were significantly worse than for first line treatment. The outcome after third line chemotherapy was very similar to that observed following second line treatment. Achievement of an objective response with first line chemotherapy predicted for second response, but with insufficient power to be of use in selecting patients for subsequent chemotherapy. Time to progression following first line chemotherapy did not influence that after second line treatment. 相似文献
109.
110.