首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   23738篇
  免费   1412篇
  国内免费   191篇
耳鼻咽喉   145篇
儿科学   653篇
妇产科学   726篇
基础医学   2898篇
口腔科学   363篇
临床医学   1624篇
内科学   5450篇
皮肤病学   554篇
神经病学   2058篇
特种医学   851篇
外国民族医学   2篇
外科学   3755篇
综合类   188篇
一般理论   8篇
预防医学   1492篇
眼科学   411篇
药学   1574篇
中国医学   91篇
肿瘤学   2498篇
  2023年   135篇
  2022年   382篇
  2021年   599篇
  2020年   396篇
  2019年   455篇
  2018年   639篇
  2017年   428篇
  2016年   509篇
  2015年   646篇
  2014年   825篇
  2013年   1125篇
  2012年   1561篇
  2011年   1551篇
  2010年   1034篇
  2009年   893篇
  2008年   1390篇
  2007年   1392篇
  2006年   1300篇
  2005年   1223篇
  2004年   1215篇
  2003年   1040篇
  2002年   1067篇
  2001年   583篇
  2000年   517篇
  1999年   484篇
  1998年   265篇
  1997年   196篇
  1996年   200篇
  1995年   188篇
  1994年   161篇
  1993年   145篇
  1992年   291篇
  1991年   264篇
  1990年   257篇
  1989年   243篇
  1988年   195篇
  1987年   159篇
  1986年   165篇
  1985年   145篇
  1984年   129篇
  1983年   102篇
  1982年   59篇
  1981年   57篇
  1979年   66篇
  1975年   41篇
  1974年   49篇
  1973年   42篇
  1969年   40篇
  1968年   45篇
  1967年   41篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
Alpha-1-antichymotrypsin in renal biopsies   总被引:1,自引:0,他引:1  
Alpha 1-Antichymotrypsin (alpha 1-AK) and alpha-1-antitrypsin (alpha 1-AT) represent a defense mechanism to protect the tissues from proteolytic enzyme activity. We studied the implication of alpha 1-AK and alpha 1-AT in glomeruli of patients with different nephropathies based on the analysis of 52 paraffin-embedded renal biopsies with alpha 1-AK and alpha 1-AT antisera. The results demonstrate an intense alpha 1-AK glomerular staining in renal biopsies from patients with minimal-change disease, while a minor staining of this protein was found in the other nephropathies. No significant evidence of alpha 1-AT deposits was observed in our cases. Our findings suggest that when alpha 1-AK is lacking in glomeruli the defense mechanisms against proteolytic enzymes may not be efficient enough to protect the glomerular structures and limit the damage. Since alpha 1-AK is a reactant of the acute phase of inflammation, it may be considered as a marker of activity for monocyte-macrophages in glomerular damage.  相似文献   
92.
In 1980, the ratio of home birth to public hospital perinatal and neonatal mortality rates decreased from Northern to Southern Italy, being inversely related to the proportion of home deliveries and probably reflecting the effect of planned versus unplanned home births. The post neonatal mortality rate in Southern Italy was about four times as high in children born at home (9.5/1,000 live births) than in those delivered in public hospitals (2.6/1,000 live births), probably reflecting differences in the socioeconomic status according to the birthplace selection in various regions.  相似文献   
93.
An influence on drug-taking behaviours of the stress-related hypothalamo-pituitary-adrenal (HPA) axis and its final hormonal mediator, corticosterone, has previously been demonstrated. A role for cortically projecting cholinergic neurons in these behaviours can also be proposed. The experiments presented here examine the effect of the drug of abuse cocaine (15 mg/kg) on the release of acetylcholine (ACh) in the cortex of freely moving rats, using the technique of in vivo microdialysis. To assess a possible modulatory influence of the HPA axis via its final hormonal mediator corticosterone, the cocaine-induced effect on cortical ACh release in intact rats was compared to that in adrenalectomized (ADX) rats, which thus lacked their endogenous source of corticosterone, and in ADX rats in which the cocaine-induced corticosterone peak and/or the basal circadian concentrations of serum corticosterone were simulated by replacement treatments. The results reported here demonstrate that cortical ACh release is greatly increased by cocaine in intact rats; ADX prolongs the return to basal levels of cortical ACh, and the chronic replacement of circadian levels of corticosterone normalizes this effect. In contrast, during the plateau period of cocaine-induced increased cortical ACh release, where no effect of ADX is evident, rats with chronic replacement of corticosterone show an attenuated cocaine-induced cortical ACh release, and the acute replacement of the cocaine-induced corticosterone secretion further attenuates this response. These results demonstrate that cocaine stimulates cortically projecting cholinergic neurons, and that the HPA hormone corticosterone modulates this interaction in a complex manner which merits further investigation.  相似文献   
94.
The case is described of a 73 year old man who presented with a lupus-like syndrome related to treatment with isoniazid and had IgG antinuclear antibodies against the nucleo-histone complex (H2A-H2B)-DNA. After a short course of treatment with prednisone and discontinuation of isoniazid the patient's lupus symptoms resolved and a gradual decrease in antibodies to (H2A-H2B)-DNA occurred. This case suggests that isoniazid is capable of inducing an autoantibody specificity associated with drug related lupus.  相似文献   
95.
96.
Results of 33 simultaneous pancreas and kidney transplantations performed at the San Raffaele Hospital, Milan, Italy are presented. In 26 cases segmental neoprene duct-injected grafts were transplanted and in seven cases, duodenopancreatic bladder-drained grafts. Five-year patient, kidney and pancreas survival were respectively, 89%,72% and 58%. Five-year survival in patients with technically successful pancreas transplants was 73%. Thrombosis occured in 20% of cases. Mortality was 6% and overall morbidity 76%. Surgical complications were present in 51% of cases.  相似文献   
97.
People undergoing medical procedures sometimes experience feelings that may influence the results. In this study, we explore the relationship between changes in mood state self-ratings and cerebral glucose metabolism during positron emission tomography (PET) in persons with age-associated memory impairment (mean age 59.4±9.8 years). Brain regions of interest involved in both mood and memory were examined. Mood ratings of increased boredom correlated significantly with mesial temporal and parietal asymmetry and decreased parietal metabolism. Mood ratings of increased fatigue correlated with basal ganglia asymmetry and the right basal ganglia and left mesial temporal metabolism. These findings suggest that subjective mood state changes during PET may influence metabolism in brain regions implicated in emotion and memory function in people with age-related memory complaints.  相似文献   
98.
99.
A comparative study of indomethacin controlled release from poly(lactide-co-glycolide) (50:50, molecular weight 3000) (PLGA) microspheres loaded with two different amounts of drug (10.9 ± 1%, and 34.1 ± 1% w/w) and pure free indomethacin, considering the effects exerted by the drug on the thermotropic behavior of dipalmitoylphosphatidylcholine multilamellar vesicles, was carried out by differential scanning calorimetry (DSC). The release was monitored by comparing the effect exerted by the free indomethacin on lipid thermotropic behavior with that of the drug released by the microspheres and relating these effects to a lipid aqueous dispersion containing the molar ratio of drug able to cause it. By DSC measurements, the pure free indomethacin was found to be able to have a fluidifying effect on the model membrane, causing a shift toward lower values of the transitional temperature (Tm), characteristic of phospholipid liposomes, without variations in the enthalpic changes (ΔH). This shift was found to be modulated by the drug molar fraction with respect to the lipid concentration in the aqueous dispersion. Successively, calorimetric measurements were performed on suspensions of blank liposomes added to weighed amounts of unloaded and indometha-cin-loaded microspheres as well as free powdered indomethacin, and the Tm shifts of the lipid bilayer caused by the drug released from the polymeric system, as well as by the free drug, were compared with that caused by free drug increasing molar fractions dispersed directly on the membrane, employed as a calibration curve to obtain the fraction of drug released. This drug release model could be employed to determine the different kinetics involved in the drug transfer from the microspheres to a membrane. This in vitro study suggests that the kinetic process involved in drug release is influenced by the amount of drug loaded in the microspheres. This calorimetric study shows that the PLGA microspheres are a good delivery system able to sustain drug release. Moreover, the DSC technique applied to the drug interaction with biomembranes constitutes a good tool for determining the drug release representing an innovative alternative in vitro model.  相似文献   
100.
The results of panoramic diagnostic microhysteroscopy are reported in 284 patients with sterility or infertility problems. In 33.5% of the patients, microhysteroscopy revealed uterine pathology; in the majority of cases they were pathologies which are unanimously recognized as being causes of sterility, while in others there were pathologies whose role infertilities is still unclear. There was a good correlation between microhysteroscopy and histology in cases of endometrial hyperplasia and of endometritis, whereas in cases of endometrial polyps and functional diagnosis of the endometrium, the correlation was less satisfactory. Although it is not possible at present to draw definite conclusions about the real value and advantages of microhysteroscopy in the diagnosis of female infertility, we are convinced that it is of great use and that it should be at the basis of any investigation involving the infertile woman.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号