全文获取类型
收费全文 | 275734篇 |
免费 | 22636篇 |
国内免费 | 6489篇 |
专业分类
耳鼻咽喉 | 3428篇 |
儿科学 | 5817篇 |
妇产科学 | 4383篇 |
基础医学 | 23406篇 |
口腔科学 | 7642篇 |
临床医学 | 29800篇 |
内科学 | 31512篇 |
皮肤病学 | 2738篇 |
神经病学 | 13685篇 |
特种医学 | 8454篇 |
外国民族医学 | 15篇 |
外科学 | 25260篇 |
综合类 | 44985篇 |
现状与发展 | 15篇 |
一般理论 | 24篇 |
预防医学 | 32952篇 |
眼科学 | 2669篇 |
药学 | 26974篇 |
407篇 | |
中国医学 | 30058篇 |
肿瘤学 | 10635篇 |
出版年
2024年 | 1082篇 |
2023年 | 5025篇 |
2022年 | 9273篇 |
2021年 | 12696篇 |
2020年 | 12319篇 |
2019年 | 13217篇 |
2018年 | 11890篇 |
2017年 | 10578篇 |
2016年 | 9740篇 |
2015年 | 9244篇 |
2014年 | 17943篇 |
2013年 | 18706篇 |
2012年 | 16067篇 |
2011年 | 17245篇 |
2010年 | 13877篇 |
2009年 | 12155篇 |
2008年 | 11585篇 |
2007年 | 11824篇 |
2006年 | 10206篇 |
2005年 | 8869篇 |
2004年 | 7549篇 |
2003年 | 6756篇 |
2002年 | 5466篇 |
2001年 | 4775篇 |
2000年 | 4115篇 |
1999年 | 3454篇 |
1998年 | 2937篇 |
1997年 | 2850篇 |
1996年 | 2307篇 |
1995年 | 2243篇 |
1994年 | 2090篇 |
1993年 | 1726篇 |
1992年 | 1625篇 |
1991年 | 1452篇 |
1990年 | 1213篇 |
1989年 | 1178篇 |
1988年 | 1122篇 |
1987年 | 961篇 |
1986年 | 896篇 |
1985年 | 2310篇 |
1984年 | 2498篇 |
1983年 | 1561篇 |
1982年 | 2104篇 |
1981年 | 1478篇 |
1980年 | 1274篇 |
1979年 | 1101篇 |
1978年 | 893篇 |
1977年 | 700篇 |
1976年 | 823篇 |
1975年 | 541篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Lymphoma arising in an adenolymphoma 总被引:1,自引:0,他引:1
A malignant lymphoma that originated in association with an adenolymphoma (Warthin's tumor) of the parotid salivary gland is reported. The occurrence of lymphomas in salivary glands is discussed briefly. 相似文献
992.
OLAV STOKLAND J
RGEN THORVALDSON ARNFINN ILEBEKK FREDRIK KIIL 《Acta physiologica (Oxford, England)》1983,117(4):481-489
To examine the factors contributing to the rise in systemic blood pressure during α- and β- adrenergic stimulation, phenylephrine, an α-adrenergic agonist, and norepinephrine, an α- and β-adrenergic agonist, were infused intravenously to anesthetized dogs until mean aortic blood pressure was raised equally by 40–60 mmHg. Changes in preload were estimated by changes in left ventricular end-diastolic pressure or segment length recorded by an ultrasonic technique. By obstructing the inferior vena cava (IVC), the increase in preload could be reduced to control level during phenylephrine and norepinephrine infusions without altering peripheral resistance (mean aortic blood pressure/cardiac output). Normalization of preload reduced the pressure response by 2/3 during phenylephrine infusion and by 1/4 during norepinephrine infusion. However, after β-adrenergic blockade by propranolol, normalization of preload reduced the pressure response by 2/3 during both phenylephrine and norepinephrine infusions. Thus, during α-adrenergic stimulation, the increase in preload is a more important factor than the increase in peripheral resistance. Norepinephrine raised stroke volume by 24±5%. When the increase in stroke volume was prevented by IVC obstruction, the pressure response to norepinephrine was halved. Thus, during norepinephrine infusion the rise in stroke volume caused by β-adrenergic stimulation is as important as α-adrenergic stimulation for the pressure response. 相似文献
993.
R.S.K. Chaganti Roller B. Bailey Suresh C. Jhanwar Zalmen A. Arlin Bayard D. Clarkson 《Cancer Genetics and Cytogenetics》1982,5(3):215-221
Malignancy in patients with constitutional chromosome abnormality is of interest not only because it permits insights into the relationship between chromosome abnormality and cancer, but also because it provides opportunities to address such questions as the clonality and evolution of tumors. We report Ph1-positive chronic myelogenous leukemia (CML) in a 50-year-old mosaic (45,X/46,XX) Turner syndrome patient whose leukemia was restricted to the monosomic cell line. Our extensive cytogenetic studies of this patient demonstrated that non-leukemic normal cells persisted in the marrow and were able to proliferate during a period of temporary suppression of the leukemic clone following aggressive treatment. 相似文献
994.
Background: Posttraumatic stress disorder (PTSD) is common in refugees but its association with longer-term psychosocial dysfunction remains unclear. We examined whether a subgroup of refugees with comorbid PTSD and depression were at particularly high risk of disability. We also investigated whether specific trauma experiences were linked to this comorbid pattern. Methods: Consecutive Bosnians (and one or two compatriots nominated by them) were recruited from a community centre, yielding a total sample of 126 participants (response rate 86%). Measures included a trauma inventory, the Clinician Administered PTSD Scale (CAPS) (Blake et al., 1995) and the depression module of the Structured Clinical Interview (SCID) (First et al., 1997). Results: Three diagnostic groupings emerged: normals (n=39), pure PTSD (n=29), and comorbid PTSD and depression (n=58). Of four trauma dimensions derived from principle components analysis (human rights violations, dispossession and eviction, life threat and traumatic loss), life threat alone was associated with pure PTSD, with life threat and traumatic loss both being associated with comorbidity. Compared to normals and those with pure PTSD, the comorbid group manifested more severe PTSD symptoms as well as higher levels of disability on all indices (global dysfunction: odds RATIO=5.0, P<0.001, distress: odds RATIO=6.0, P<0.001, social impairment: odds ratio 5.9, P<0.001, and occupational disability: odds ratio 5.0, P<0.001). Limitations: Recruitment was not random, the sample size was modest, and trauma event endorsement was based on retrospective accounts. Conclusions: The combination of life threat and traumatic loss may be particularly undermining to the psychological well-being of refugees and consequent comorbidity of PTSD and depression may be associated with longer-term psychosocial dysfunction. The findings raise the question whether the comorbid pattern identified should be given more recognition as a core posttraumatic affective disorder. 相似文献
995.
Bartha Maria Knoppers 《American journal of medical genetics. Part A》2002,108(1):29-35
The word “serious” appears in laws and policies regarding genetics services but is not defined. Genetics professionals would most likely be consulted if definitions are made. We surveyed all U.S. board‐certified genetics services providers and all members of the European Society of Human Genetics (ESHG), Canadian College of Medical Geneticists (CCMG), and Ibero‐American Society of Human Genetics (IASHG), using anonymous, mailed questionnaires. Respondents were asked to list three conditions they considered lethal, three that were serious but not lethal, and three that were not serious. Of 3,317 asked to respond, 1,481 (45%) returned questionnaires. Analysis was limited to responses of the 1,264 (85%) who saw patients. Respondents listed 537 conditions, with extensive overlap between categories; 46% of conditions listed as serious were also listed as not serious and 41% were listed as lethal. Respondents did not want professional societies, laws, or national ethics committees to define serious. They favored individual patients as decision makers, with the help of individual doctors. Their reasons were that genetic disorders vary in expression, individuals perceive disorders differently, professional or legal definitions could be unfair to minority groups, definitions tend to be inflexible when new treatments appear. In the United States, most would not use a definition of serious to limit reproductive services, carrier screening, or neonatal intensive care; outside the United States, more supported limitations. There is not sufficient consensus among experienced genetics professionals to define serious genetic conditions for purposes of law or policy. Responses point to social and economic influences on perceptions of what constitutes a serious genetic disorder. © 2002 Wiley‐Liss, Inc. 相似文献
996.
A new test for the assessment of sperm- zona pellucida penetration: relationship with results of other sperm tests and fertilization in vitro 总被引:1,自引:0,他引:1
The spermatozoa of some patients attending for in-vitro fertilization(IVF) fail to penetrate the zona pellucida in vitro. A testhas been devised to identify these cases. It is based on thenumber of spermatozoa penetrating into the zona pellucida, whichwere counted after removing spermatozoa bound to the zona surfaceby vigorous aspiration of each oocyte through a narrow gauge(120 µm) glass pipette. The oocytes were collected from197 patients undergoing IVF treatment with their own gametes;79 with no oocytes fertilized and 118 with some oocytes fertilized.Sperm motility, morphology and DNA normality (acridine orangestain) were also measured. The relationships between sperm testresults and IVF rate were examined by logistic regression. Theproportions of penetrated zonae, normal sperm morphology andnormal DNA were the most significant factors related to IVFrate in the whole group. Also, in patients with 30 spermatozoabound per zona pellucida or with normal sperm morphology 30%,the proportion of penetrated zonae and normal DNA were mostsignificant. Oocytes from 42 patients who had zero fertilizationand low sperm-zona binding (average, 2.2 spermatozoa/zona pellucida)were re-incubated with normal donor spermatozoa: large numbersof spermatozoa bound (average, 88 spermatozoa/zona pellucida)and each zona was penetrated by at least one spermatozoon. Inconclusion, the percentage of zonae penetrated was the variablemost significantly correlated with IVF rate. Penetration ofthe zona was also strongly related to fertilization rates inpatients without defects of sperm morphology and sperm-zonabinding. In patients where all zonae were penetrated, poor fertilizationmay be due to sperm morphology and DNA abnormalities. Failureof sperm-zona binding and penetration in vitro in patients withfailure of fertilization was mainly due to sperm defects andnot oocyte defects 相似文献
997.
We tested the hypothesis that pharmacological reduction of the increase in cardiac output during dynamic exercise with a large muscle mass would influence the cerebral blood velocity/perfusion. We studied the relationship between changes in cerebral blood velocity (transcranial Doppler), rectus femoris blood oxygenation (near-infrared spectroscopy) and systemic blood flow (cardiac output from model flow analysis of the arterial pressure wave) as induced by dynamic exercise of large (cycling) vs. small muscle groups (rhythmic handgrip) before and after cardioselective β1 adrenergic blockade (0.15 mg kg?1 metoprolol i.v.). During rhythmic handgrip, the increments in systemic haemodynamic variables as in middle cerebral artery mean blood velocity were not influenced significantly by metoprolol. In contrast, during cycling (e.g. 113 W), metoprolol reduced the increase in cardiac output (222 ± 13 vs. 260 ± 16%), heart rate (114 ± 3 vs. 135 ± 7 beats min?1) and mean arterial pressure (103 ± 3 vs.112 ± 4 mmHg), and the increase in cerebral artery mean blood velocity also became lower (from 59 ± 3 to 66 ± 3 vs. 60 ± 2 to 72 ± 3 cm s?1; P < 0.05). Likewise, during cycling with metoprolol, oxyhaemoglobin in the rectus femoris muscle became reduced (compared to rest; ?4.8 ± 1.8 vs. 1.2 ± 1.7 μmol L?1, P < 0.05). Neither during rhythmic handgrip nor during cycling was the arterial carbon dioxide tension affected significantly by metoprolol. The results suggest that as for the muscle blood flow, the cerebral circulation is also affected by a reduced cardiac output during exercise with a large muscle mass. 相似文献
998.
Marc Gellman Susan Spitzer Gail Ironson Maria Llabre Patrice Saab Rosemary De Carlo Pasin Donald J. Weidler Neil Schneiderman 《Psychophysiology》1990,27(5):544-551
Ambulatory blood pressure was studied as a function of posture, place, and mood in 131 subjects classified according to race, gender, and hypertensive status. The effect of posture was significant and explained a substantial proportion of within-subject variability. After controlling for posture, significant place and mood effects were observed when subjects were sitting but not when they were standing. Home vs. work differences in both systolic and diastolic blood pressure were significantly greater in Whites than in Blacks. Similar differences in systolic blood pressure were greater in mild hypertensive than in normotensive subjects. The results of this study underscore the need to control for effects of posture when interpreting ambulatory blood pressure readings. 相似文献
999.
目的:探讨脂血、高胆红素和溶血标本对乙肝病毒DNA(HBVDNA)荧光定量测定结果的影响。方法:将乙肝大三阳高脂血和非脂血、溶血血清和未溶血血清同时作HBVDNA荧光定量检测;将HBVDNA阴性黄疸血清和HBVDNA阴性正常血清与来自同一份乙肝大三阳血清混合,在相同条件下进行HBVDNA荧光定量。结果:乙肝大三阳溶血与未溶血样本HBVDNA含量都在同一数量级。乙肝大三阳高脂血的HBVDNA含量明显低于对照标本。高黄疸血清、正常对照血清与相同的HBVDNA阳性模板组合后所测得的HBVDNA结果无差异。结论:脂血对HBVD-NA定量测定有严重干扰;溶血样本、高胆红素样本对HBVDNA测定结果无影响。 相似文献
1000.