全文获取类型
收费全文 | 4711篇 |
免费 | 438篇 |
国内免费 | 85篇 |
专业分类
耳鼻咽喉 | 16篇 |
儿科学 | 221篇 |
妇产科学 | 77篇 |
基础医学 | 612篇 |
口腔科学 | 121篇 |
临床医学 | 622篇 |
内科学 | 928篇 |
皮肤病学 | 71篇 |
神经病学 | 306篇 |
特种医学 | 404篇 |
外国民族医学 | 1篇 |
外科学 | 508篇 |
综合类 | 126篇 |
一般理论 | 5篇 |
预防医学 | 499篇 |
眼科学 | 55篇 |
药学 | 274篇 |
中国医学 | 8篇 |
肿瘤学 | 380篇 |
出版年
2021年 | 50篇 |
2019年 | 52篇 |
2018年 | 54篇 |
2017年 | 50篇 |
2016年 | 51篇 |
2015年 | 69篇 |
2014年 | 84篇 |
2013年 | 164篇 |
2012年 | 162篇 |
2011年 | 184篇 |
2010年 | 118篇 |
2009年 | 126篇 |
2008年 | 199篇 |
2007年 | 190篇 |
2006年 | 152篇 |
2005年 | 143篇 |
2004年 | 177篇 |
2003年 | 159篇 |
2002年 | 167篇 |
2001年 | 173篇 |
2000年 | 140篇 |
1999年 | 136篇 |
1998年 | 123篇 |
1997年 | 120篇 |
1996年 | 100篇 |
1995年 | 91篇 |
1994年 | 78篇 |
1993年 | 80篇 |
1992年 | 123篇 |
1991年 | 93篇 |
1990年 | 100篇 |
1989年 | 112篇 |
1988年 | 96篇 |
1987年 | 100篇 |
1986年 | 88篇 |
1985年 | 103篇 |
1984年 | 71篇 |
1983年 | 56篇 |
1982年 | 43篇 |
1980年 | 43篇 |
1979年 | 71篇 |
1978年 | 40篇 |
1977年 | 39篇 |
1975年 | 40篇 |
1974年 | 43篇 |
1973年 | 47篇 |
1972年 | 50篇 |
1971年 | 45篇 |
1969年 | 46篇 |
1968年 | 39篇 |
排序方式: 共有5234条查询结果,搜索用时 15 毫秒
81.
The ensheathment of the olfactory nerve fibres is achieved by cooperation of two cell types. The olfactory ensheathing cells have a rounded outer surface enclosed in a continuous single basal lamina, and enclose an inner compartment from which overlapping processes of the same and adjacent cells enwrap interweaving territories of tightly apposed aligned axons. The olfactory nerve fibroblasts are highly flattened, dense cells generating multiple layers of very thin processes encircling individual or groups of olfactory ensheathing cells. This paper illustrates the unique ultrastructural features of this ensheathment. 相似文献
82.
Although infants have been noted to have greater relative right or left frontal EEG as early as the neonatal period, other ways in which these newborns differ have not been reported. In this study, 48 newborns were divided on the basis of greater relative right versus greater relative left frontal EEG to determine whether these groups differed in other ways at the neonatal period including behavior, physiology, and biochemistry. We also were interested in whether these EEG patterns were related to any prenatal maternal variables including mood states (depression, anxiety, anger) and biochemistry as well as fetal activity. The greater relative right frontal EEG newborns had mothers with lower prenatal and postnatal serotonin and higher postnatal cortisol levels. The mothers of the greater relative right frontal EEG newborns also had greater relative right frontal EEG activation and lower vagal tone. The greater relative right frontal EEG newborns themselves had elevated cortisol levels, showed a greater number of state changes during sleep/wake behavior observations, and performed less optimally on the Brazelton Neonatal Behavior Assessment (T. B. Brazelton, 1973) including the habituation, motor, range of state, excitability, and depressive symptoms scales. These data suggest that greater relative right frontal EEG newborns may be at greater risk for developmental problems than those with greater relative left frontal EEG activation. In addition, a discriminant function analysis correctly classified 67% of the newborns' EEGs by prenatal maternal variables, suggesting that these might be used to target pregnant women for prenatal intervention. 相似文献
83.
The prevalence of complement-fixing (CF) antibody against the AG-4 early antigen of herpes simplex virus (HSV) type 2 (HSV-2) was determined in patients with culture confirmed HSV-2 genital herpes and control groups using a commercial HSV-2 early antigen (Simplex-2; Gene Link Australia Ltd). Eighty seven per cent of 39 sera collected between 14 and 28 days after confirmed primary and recurrent HSV-2 infection were positive. In acute sera collected between 2-10 days after onset the Simplex-2 test was negative in all 90 patients with presumed primary infection but positive in 53% of 230 sera from recurrent infection. A specificity of 90-94.5% was obtained by testing 36 patients with recent proven HSV-1 infection and 331 control group patients. The Simplex-2 test may be useful in some cases of culture-negative, clinically suspected genital HSV-2 lesions only when sera are collected between 14-28 days after primary and recurrent infection. Its lack of specificity makes it unsuitable for the routine diagnosis of recent HSV-2 infection in the general population. 相似文献
84.
Eme L Iloeje Michael J. Katovich Edward E. Soltis F. Peter Field 《Pharmaceutical research》1985,2(6):298-301
Alterations in - and -adrenergic responsiveness were investigated prior to and during the development of hypertension in rats treated with desoxycorticosterone acetate and NaCl (DOCA/ NaCl). The DOCA/NaCl rats became noticeably hypertensive (> 150 mm Hg) six weeks after the initiation of treatment. Prior to the development of hypertension, a reduced in vivo and in vitro - and an enhanced -adrenergic responsiveness of the DOCA/NaCl group resulted. At 2 and 12 weeks of the study, the dipsogenic response to isoproterenol was significantly attenuated in the DOCA/NaCl rats, whereas no difference in the dipsogenic response to 24 hour water deprivation was observed between control and DOCA/NaCl rats. Isoproterenol-induced relaxation of aortic smooth muscle from the DOCA/NaCl treated rats was significantly reduced at 4 weeks and further attenuated at 12 weeks of the study. However, aortic smooth muscle sensitivity to norepinephrine stimulation was significantly increased at 4 and 12 weeks of the study. These results suggest that alterations in both in vivo and in vitro - and -adrenergic responsiveness occur prior to establishment of hypertension of the DOCA/NaCl rats and that these alterations may have a role in the early stages of the development of this form of hypertension. 相似文献
85.
J C Thomas L L Wiltse E H Widell C W Spencer M R Zindrick B T Field 《Clinical orthopaedics and related research》1986,(206):61-66
An 11.8-year median follow-up evaluation of 42 "ideal" patients who had chemonucleolysis was obtained by examination, questionnaire, and roentgenograms. The excellent and good rating of this group was 81%, as compared to the total of 135 patients previously evaluated at 42 months and showing 85.2%. No complications were noted. Disc space rewidening, after initial narrowing, was observed in eight patients and 26% of all discs injected. While all who showed rewidening had excellent results, widening was not necessary to achieve an excellent rating. Marked narrowing and sclerosis of intervertebral margins were seen in many excellent and good clinical results. Chemonucleolysis represents a viable option as definitive treatment for a herniated nucleus pulposus in carefully selected patients. 相似文献
86.
87.
Zaeem Lone Prithvi B. Murthy JJ Haijing Zhang Kyle J. Ericson Lewis Thomas Abhinav Khanna Georges-Pascal Haber Byron H. Lee 《Urologic oncology》2021,39(5):301.e1-301.e9
PurposeRenal function outcomes following robot-assisted radical cystectomy (RARC) have not been well established. We sought to compare long-term renal function outcomes between open radical cystectomy, RARC with extracorporeal urinary diversion and intracorporeal urinary diversion at a high volume institution.Materials and MethodsWe retrospectively reviewed our institutional bladder cancer database for patients who underwent RC from 2010 to 2019 with pre-operative estimated glomerular filtration rate (eGFR) > 45 ml/min/1.73m2. Changes in renal function were assessed through locally weighted scatter plot smoothing and comparison of median eGFR between surgical groups. Chronic Kidney Disease Stage 3B was defined as eGFR < 45 ml/min/1.73m2. Renal function decline was defined as a ≥10 ml/min/1.73m2 drop in eGFR. Kaplan Meier method with log-rank was used to compare CKD 3B-free survival and renal function decline. Cox Proportional Hazards model was used to identify predictors of CKD 3B.ResultsSix hundred and forty four patients were included with median follow-up of 32 months (IQR 12–56). Preoperative characteristics were similar among the groups with no differences in median pre-operative eGFR (ORC: 74.6, extracorporeal urinary diversion: 74.3, intracorporeal urinary diversion: 71.6 ml/min/1.73m2, P = 0.15). Median postoperative eGFR on follow up was not different between groups (P = 0.56). 33% of patients developed CKD 3B. There were no differences in CKD 3B-free survival by surgical approach (P = 0.23) or urinary diversion (P = 0.09). 64% of patients experienced renal function decline with a median time of 2.4 years (P 0.23). Predictors of CKD were pathologic T3 disease or greater (HR: 1.77, P = 0.01), ureteroenteric anastomotic stricture (HR: 2.80, P < 0.001), preoperative CKD Stage 2 (HR: 1.81, P =0.02), and preoperative CKD Stage 3A (HR: 5.56, P < 0.001).ConclusionRenal function decline is common after RC. Tumor stage, pre-operative eGFR, and ureteral stricture development, not surgical approach, influence renal function decline. 相似文献
88.
89.
Single sperm typing demonstrates that reduced recombination is associated with the production of aneuploid 24,XY human sperm 总被引:13,自引:0,他引:13
Shi Q Spriggs E Field LL Ko E Barclay L Martin RH 《American journal of medical genetics》2001,99(1):34-38
To account for the increased proportion of paternal nondisjunction in 47,XXY males as compared to other trisomies, it has been suggested that the XY bivalent, with its reduced region of homology, is particularly susceptible to nondisjunction. Molecular studies of liveborn Klinefelter syndrome (47,XXY) individuals have reported an association between the absence of recombination in the pseudoautosomal region and nondisjunction of the XY bivalent. In this study we examined single sperm from a normal 46,XY male to determine if there is any alteration in the recombination frequency of aneuploid disomic 24,XY sperm compared to unisomic sperm (23,X or Y). Two DNA markers STS/STS pseudogene and DXYS15 were typed in sperm from a heterozygous man to determine if recombination had occurred in the pseudoautosomal region. Individual unisomic sperm (23,X or Y) were isolated using a FACStar(Plus) flow cytometer into PCR tubes. To identify disomic 24,XY sperm, 3-colour FISH analysis was performed with probes for chromosomes X,Y and 1. The 24,XY cells were identified using fluorescence microscopy, each disomic sperm was scraped off the slide using a glass needle attached to a micromanipulator and then put into a PCR tube. Hemi-nested PCR analysis of the two markers was performed to determine the frequency of recombination. A total of 329 unisomic sperm and 150 disomic sperm have been typed. The frequency of recombination between the two DNA markers was 38.3% for the unisomic sperm, similar to frequencies previously reported. The 24,XY disomic sperm had an estimated recombination frequency of 25.3%, however, a highly significant decrease compared to the unisomic 23,X or 23,Y sperm (chi(2) = 10.7, P = 0.001). This direct analysis of human sperm indicates that lack of recombination in the pseudoautosomal region is a significant cause of XY nondisjunction and thus Klinefelter syndrome. Copyright Wiley-Liss. Inc. 相似文献
90.
A patient with severe hyperemesis gravidarum persisting throughout pregnancy is described. She had marked abnormalities of liver function and failed to respond to conservative management. Total parenteral nutrition was used to maintain her nutritional status as well as that of the foetus. Her vomiting continued and was complicated by severe oesophagitis. On delivery her symptoms settled, but she later developed an oesophageal stricture. Changes in liver function tests are described. 相似文献