全文获取类型
收费全文 | 19626篇 |
免费 | 1347篇 |
国内免费 | 35篇 |
专业分类
耳鼻咽喉 | 169篇 |
儿科学 | 650篇 |
妇产科学 | 339篇 |
基础医学 | 2459篇 |
口腔科学 | 980篇 |
临床医学 | 2222篇 |
内科学 | 3351篇 |
皮肤病学 | 194篇 |
神经病学 | 1780篇 |
特种医学 | 763篇 |
外国民族医学 | 2篇 |
外科学 | 2587篇 |
综合类 | 264篇 |
一般理论 | 14篇 |
预防医学 | 1976篇 |
眼科学 | 540篇 |
药学 | 1319篇 |
中国医学 | 13篇 |
肿瘤学 | 1386篇 |
出版年
2021年 | 233篇 |
2020年 | 162篇 |
2019年 | 276篇 |
2018年 | 284篇 |
2017年 | 240篇 |
2016年 | 261篇 |
2015年 | 296篇 |
2014年 | 407篇 |
2013年 | 692篇 |
2012年 | 950篇 |
2011年 | 1128篇 |
2010年 | 589篇 |
2009年 | 583篇 |
2008年 | 1033篇 |
2007年 | 1104篇 |
2006年 | 1146篇 |
2005年 | 1119篇 |
2004年 | 1047篇 |
2003年 | 943篇 |
2002年 | 976篇 |
2001年 | 421篇 |
2000年 | 377篇 |
1999年 | 354篇 |
1998年 | 221篇 |
1997年 | 216篇 |
1996年 | 179篇 |
1995年 | 176篇 |
1994年 | 144篇 |
1993年 | 143篇 |
1992年 | 301篇 |
1991年 | 319篇 |
1990年 | 295篇 |
1989年 | 323篇 |
1988年 | 275篇 |
1987年 | 284篇 |
1986年 | 254篇 |
1985年 | 245篇 |
1984年 | 233篇 |
1983年 | 185篇 |
1982年 | 151篇 |
1981年 | 149篇 |
1980年 | 140篇 |
1979年 | 191篇 |
1978年 | 150篇 |
1977年 | 137篇 |
1976年 | 154篇 |
1975年 | 122篇 |
1974年 | 150篇 |
1973年 | 159篇 |
1972年 | 138篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
Temporal Changes in Micturition and Bladder Contractility after Sucrose Diuresis and Streptozotocin-induced Diabetes Mellitus in Rats 总被引:2,自引:0,他引:2
Teuvo L.J. Tammela Robert E. Leggett Robert M. Levin Penelope A. Longhurst 《The Journal of urology》1995,153(6):2014-2021
Studies were done to compare the acute effects of streptozotocin-induced diabetes and sucrose consumption on micturition, bladder mass and contractile responses of bladder strips to field stimulation and contractile agonists. Micturition changes occurred gradually in diabetic rats, reached maximal values within 7 to 14 days, and were accompanied by significant increases in bladder mass after 7 days. Bladder strips from diabetics responded to field stimulation, carbachol and KCl with significantly greater contractions than did those from controls within 7 days. Sucrose-drinking rats had maximal increases in fluid consumption and micturition frequency on the first night after starting treatment. Increases in micturition volumes were slower to develop than in diabetics. Bladder mass was significantly increased 30 and 60 days after starting sucrose treatment. Bladder strips from sucrose-drinking rats responded to field stimulation and carbachol with significantly greater contractions than did those from controls only after 60 days. Monitoring of drinking and micturition patterns established that diabetic rats drink and urinate during both the dark and light cycles. In contrast, control and sucrose-drinking rats drink and urinate principally at night. The results demonstrate that differences in bladder function between diabetic and sucrose drinking rats are apparent during the first month after treatment begins. The data suggest that the effects of diabetes and sucrose consumption on contractile bladder function are related to the diuresis-induced increases in bladder mass. 相似文献
32.
S Warach J M Levin D L Schomer B L Holman R R Edelman 《AJNR. American journal of neuroradiology》1994,15(5):965
MR using a susceptibility-weighted sequence and dynamic contrast enhancement with gadolinium demonstrated relative hyperperfusion of the right temporoparietal cortex in a patient in focal status epilepticus. A single-photon emission CT (SPECT) scan also demonstrated hyperperfusion of the right temporoparietal cortex. Perfusion MR, SPECT, and electroencephalogram normalized when the seizures ended. 相似文献
33.
Despite growth in the field of gerontological research over the past 50 years, no consensus has emerged on either the definition of gerontology or on its scope and boundaries. This confusion is rooted historically in developments involving the origins and adoption of the term. These include the divergent agendas and world views of particular disciplines and gerontological institutions, as well as conflicts over both ideology and turf among major gerontologists. Speculation is offered on the potential, as well as the costs, of developing consensus-in the future. 相似文献
34.
35.
The urinary bladder, as do all smooth muscle organs, depends on the delivery of oxygen and metabolic substrates for proper functioning. Although glucose metabolism has been studied and evaluated for a variety of smooth muscle systems, little is known about carbohydrate metabolism of the urinary bladder. In the present investigation glucose metabolism and glycogen formation of the urinary bladder of the rabbit was studied in vitro. Isolated urinary bladder strips were prepared from bladder base and body and the following metabolic determinations were made: glucose utilization, glycogen formation, CO2, and lactic acid formation. In addition, the effect of insulin on glucose metabolism was investigated. Glucose utilization was similar in bladder base and body (6.57 +/- 0.67 mumols/gm./2 hours in combined tissues). Eighty-one percent of the glucose utilized was metabolized to lactate whereas 11% was oxidized to CO2 and 4.7% was incorporated into glycogen. Insulin caused a small but significant increase in glucose utilization by bladder strips. 相似文献
36.
Peter R. Martin Sondra Levin Giovanni Impeduglia Yoomi Choe John Karanian Anil B. Mukherjee 《Psychopharmacology》1989,97(2):253-256
To determine whether prenatal thiamine deficiency, a frequent concomitant of alcoholism, reduces the response to ethanol during adulthood in the rat as does ethanol exposure in utero (Abel et al. 1981), pregnant Sprague-Dawley rats received either control or thiamine deficient diets together with daily injections of the thiamine antagonist pyrithiamine. At 7 months of age, male offspring were exposed to precisely regulated ethanol vapor concentrations in an inhalation chamber for 24 h and blood ethanol concentrations (BECs) and ethanol-induced intoxication were determined. Prenatally thiamine deficient rats and controls were indistinguishable in terms of appearance, body and liver weights, and the ratios of liver to body weight and brain to liver weight. However, total body water was significantly greater, and BECs and behavioral impairment were decreased, in the experimental rats. These findings indicate that prenatal thiamine deprivation is associated with reduced pharmacologic effect of ethanol as a result of increases in its volume of distribution and rate of metabolism. 相似文献
37.
A S Levin A A Barone M Shiroma 《Revista do Instituto de Medicina Tropical de S?o Paulo》1989,31(4):213-220
24 cases of fulminant hepatitis (FH) hospitalized in the Clínica de Doen?as Infecciosas e Parasitárias do Hospital das Clínicas da Faculdade de Medicina da Universidade de S?o Paulo during the period from January 1976 to December 1986 were reviewed from their clinical, epidemiological and laboratorial aspects. 88% of the patients died; 20 patients (83%) presented hemorrhages and, of these, 19 died. Bacterial infections occurred in 14 patients (58%) all of whom died. Ascitis was noted in 3 cases; cerebral edema was present in 16 cases. Maximal ALT levels for each patient during hospitalization ranged widely from 81 to 4,460 UI/l. Thirteen patients presented high creatinine levels (54%). Prothrombin time activity ranged from 2.1% to 67%. Fever was present in 20 cases (83%). Encephalopathy occurred within the first 2 weeks of illness in 72% of the cases. In 7 cases other illnesses were present. The etiology could not be determined in 13 cases. In 3 cases it was due to yellow fever and 6 cases were caused by viruses other than yellow fever. In one case the cause was drug usage and in another case, possibly alcohol. The authors believe that the clinical definition of FH requires further discussion before it is established. In this study FH is a young person's disease. The mortality found was similar to that by other authors. Factors that contributed to death were: hemorrhages and bacterial infection. Factors that worsened the prognosis of hepatitis were: associated illnesses and surgical procedure. The levels of ALT during hospitalization did not correlate well with the severity of the hepatitis.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
38.
It has been recently suggested that nitrofurantoin may induce symptoms of interstitial cystitis by acting as a surface active agent that destroys glycosaminoglycan (GAG) on the bladder surface. Evidence accumulated over the past decade has demonstrated that the bladder surface GAG prevents bacterial adherence. In this experiment, exposure of the bladder lumen to nitrofurantoin at more than twice the therapeutic concentration did not destroy the bladder GAG layer (as evidenced by periodic acid-Schiff histochemistry) nor increase bacterial adherence as did a true surface active agent (Triton X-100). Acid treatment as well as all tested organic solvents except 50% dimethyl sulfoxide (DMSO) also removed the bladder GAG layer and increased bacterial adherence. These results indicate that neither nitrofurantoin nor 50% DMSO has adverse effects on the bladder surface and thus is unlikely to initiate the interstitial cystitis symptom complex by means of surfactant activity. 相似文献
39.
40.
Radiation levels near an imaging chain commonly used in angiography were measured with both a 100- and a 200-mm-thick scatter phantom. The scatter was measured in lines parallel in space to the central ray of the x-ray beam, at lateral distances of 300, 500, and 800 mm. The effects of fluoroscopic kilovoltage and image intensifier magnification mode were also measured. The results indicate that the highest scattered radiation levels occur near the surface of the patient where the x-ray beam enters. Exposure rates were measured in both anteroposterior (AP) and posteroanterior (PA) geometries on a U-arm system. In PA geometry, the highest radiation levels occur below the angiographer's waist, an area well protected by the lead apron. The AP geometry increases the exposure rate to the neck, head, and upper extremities, areas where apron shielding is less effective. 相似文献