全文获取类型
收费全文 | 28712篇 |
免费 | 2367篇 |
国内免费 | 49篇 |
专业分类
耳鼻咽喉 | 347篇 |
儿科学 | 1033篇 |
妇产科学 | 677篇 |
基础医学 | 3459篇 |
口腔科学 | 593篇 |
临床医学 | 3668篇 |
内科学 | 5274篇 |
皮肤病学 | 443篇 |
神经病学 | 2774篇 |
特种医学 | 1088篇 |
外科学 | 3629篇 |
综合类 | 695篇 |
一般理论 | 46篇 |
预防医学 | 3169篇 |
眼科学 | 507篇 |
药学 | 2158篇 |
2篇 | |
中国医学 | 33篇 |
肿瘤学 | 1533篇 |
出版年
2021年 | 398篇 |
2020年 | 235篇 |
2019年 | 349篇 |
2018年 | 423篇 |
2017年 | 301篇 |
2016年 | 359篇 |
2015年 | 411篇 |
2014年 | 619篇 |
2013年 | 938篇 |
2012年 | 1173篇 |
2011年 | 1331篇 |
2010年 | 764篇 |
2009年 | 568篇 |
2008年 | 1161篇 |
2007年 | 1300篇 |
2006年 | 1291篇 |
2005年 | 1195篇 |
2004年 | 1200篇 |
2003年 | 1033篇 |
2002年 | 972篇 |
2001年 | 969篇 |
2000年 | 981篇 |
1999年 | 776篇 |
1998年 | 304篇 |
1997年 | 294篇 |
1996年 | 261篇 |
1995年 | 253篇 |
1994年 | 217篇 |
1992年 | 691篇 |
1991年 | 707篇 |
1990年 | 656篇 |
1989年 | 621篇 |
1988年 | 602篇 |
1987年 | 562篇 |
1986年 | 568篇 |
1985年 | 547篇 |
1984年 | 432篇 |
1983年 | 421篇 |
1982年 | 272篇 |
1981年 | 255篇 |
1980年 | 236篇 |
1979年 | 426篇 |
1978年 | 311篇 |
1977年 | 270篇 |
1976年 | 244篇 |
1975年 | 234篇 |
1974年 | 299篇 |
1973年 | 261篇 |
1972年 | 233篇 |
1971年 | 226篇 |
排序方式: 共有10000条查询结果,搜索用时 625 毫秒
101.
D L Goad C M Davis P Liem C C Fuselier J R McCormack K M Olsen 《The Journal of clinical psychiatry》1991,52(8):342-345
BACKGROUND: Currently there is no regimen for managing the inappropriate behavior seen in Alzheimer's disease that does not cause significant patient sedation. Preliminary evidence suggests selegiline may be effective in behavioral modification without the adverse effects observed with other regimens. The purpose of this study was to document the efficacy of selegiline in Alzheimer's patients with behavior problems. METHOD: Eight Alzheimer's patients (6 women and 2 men) ranging in age from 50 to 82 years (mean +/- SD = 74.0 +/- 10.5) were enrolled in this single-blind study. Patients received selegiline 10 mg each day for 8 weeks. Prior to drug administration and at the end of Weeks 1, 2, 4, 6, and 8, patients were evaluated for behavior (BEHAVEAD), cognitive function (Mini-Mental State Examination), and caregiver stress (Caregiver Burden Scale). RESULTS: Of eight enrolled patients, five were available for analysis. No statistically significant differences were found between mean baseline and mean 8-week scores for any of the three tests. However, clinical significance was noted by improvement in cognition (orientation and recall), caregiver stress, and behavior. Behavior was noted to improve in the areas of paranoid and delusional ideation, hallucinations, activity disturbances, anxiety, and phobias. CONCLUSION: These data suggest that some Alzheimer's patients with behavior problems may benefit from selegiline therapy. 相似文献
102.
After years of decline to near disappearance, there recently has been an increasing incidence of syphilis in America. New cases of tertiary neurosyphilis are being reported which often have associated significant urologic sequelae. For the first time in the English literature, the uro-dynamic findings of a patient with tabes dorsalis are presented. Our findings indicate that treatment of urinary retention associated with tabes dorsalis is better managed by intermittent catheterization than by prostate surgery because of the impaired detrusor activity. A review of neurosyphilis and its urologic implications and urodynamic findings are presented. Prompt recognition of this entity should encourage a full urodynamic evaluation prior to a commitment to prostatic surgery. 相似文献
103.
Renal transplantation from elderly living donors 总被引:1,自引:0,他引:1
N Sumrani V Delaney Z K Ding R Davis P Daskalakis A Tejani K Butt J Hong 《Transplantation》1991,51(2):305-309
A worldwide shortage of cadaveric donors has led to the increased utilization of elderly living donors, with controversial results. In an attempt to assess the effect of donor age on graft survival and subsequent renal function, we analyzed our clinical results in 276 consecutive recipients of living related renal transplants spanning both the cyclosporine and the azathioprine eras, of whom a total of 44 recipients received kidneys from donors over 55 years old. All recipients were otherwise similar in age, race, haplotype mismatch, number of retransplants, and number of pretransplant transfusions, apart from an increased number of diabetics among the CsA-treated recipients of elderly kidneys (38% vs. 14%). The cumulative patient and graft survival rates at 1 and 5 years were independent of donor age whether CsA or AZA was utilized. Nor was the incidence of rejection or infection significantly different in the older donor group when compared with the younger cohort. Short-term and intermediate-term renal function, as assessed by serum creatinine, was however poorer but stable in the older donor group when compared with the younger one. The mean serum creatinine levels at 1 year in the CsA- and AZA-treated recipients of kidneys from older donors were 2.4 and 2.0 mg/dl, respectively, compared with 1.6 and 1.4 mg/dl, respectively, when the donor age was less than 55 years (P less than 0.001). Since renal function at the end of the first posttransplant year is considered a determinant of long-term graft survival, this is a cause for concern, but in view of the universal shortage of organs and the negligible morbidity to donors, renal transplantation from elderly living donors remains an acceptable practice. 相似文献
104.
A psychobiological perspective on the personality disorders 总被引:3,自引:0,他引:3
A preliminary but growing body of evidence supports the existence of genetic and biological substrates of personality, suggesting the utility of a psychobiological perspective on the personality disorders. The investigation of biological correlates of personality disorders can provide an empirical base to explore the relationship between biological predispositions and psychological function. The authors propose a psychobiological model based on dimensions of cognitive/perceptual organization, impulsivity/aggression, affective instability, and anxiety/inhibition. These dimensions span the DSM-III-R axis I and axis II disorders. The authors review phenomenological, genetic, and biological evidence in relation to each of these dimensions. Although such an approach remains heuristic, this model provides a promising vantage point from which to generate investigation of the development and treatment of the personality disorders. 相似文献
105.
Systemic administration of the phosphodiesterase inhibitor rolipram (0.05–10.0 mg/kg, IP) produced a rapid and dose-related
increase in the amplitude of the acoustic startle response in rats. The (−) isomer was more potent than the (+) isomer in
enhancing startle amplitude. Rolipram increased startle responses that were elicited by brief electrical stimulation of the
ventral cochlear nucleus or nucleus reticularis pontis caudalis, two brainstem relay nuclei of the startle neural circuit.
A low (5 μg) dose of rolipram produced an excitatory effect on startle following spinal (lumbar intrathecal) infusion but
not following supraspinal (lateral ventricle) infusion. Rolipram (0.5 mg/kg, IP) excitation of startle was not blocked by
drugs which differentially disrupt the release of monoamines (DSP4, reserpine + alpha-methylpara-tyrosine, reserpine + para-chloro-phenylalanine)
or by drugs which differentially block monoamine receptors (haloperidol, prazosin, idazoxan, cinanserin, or cyproheptadine).
The marked increase in startle seen following systemic rolipram injection is attributable, at least in part, on an action
in the lumbar spinal cord that directly or indirectly facilitates neural transmission along the reticulospinal component of
the startle reflex neural pathway. The startle reflex should be a useful behavioral test system for studying the mechanism
of action of rolipram and related compounds purported to selectively inhibit calmodulin-independent forms of phosphodiesterase. 相似文献
106.
Exercise training ameliorates progressive renal disease in rats with subtotal nephrectomy 总被引:7,自引:0,他引:7
To determine the effect of chronic exercise training on renal function in animals with moderate renal insufficiency, rats with 75% renal ablation were either exercise trained by swimming for two months or remained sedentary. Glomerular filtration rate was significantly higher in trained (1.89 +/- 0.07 ml/min) than in sedentary rats (1.52 +/- 0.11 ml/min). No change was observed in renal blood flow or the degree of hypertension. Proteinuria was reduced in trained (13.6 +/- 4.9 mg/24 hr) compared to sedentary animals (33.5 +/- 9.2 mg/24 hr). The degree of glomerulosclerosis was much less prominent in trained animals. Plasma, low-density lipoprotein cholesterol-levels and total triglycerides were reduced in trained compared to sedentary rats. This study suggests that chronic exercise training ameliorates the progression of renal disease and improves plasma lipids in rats with moderate renal insufficiency. The mechanism for this improvement in renal function appears to be independent of the influence of systemic blood pressure. 相似文献
107.
We have previously identified two broad electrophysiological classes of spiral ganglion neuron that differ in their rate of accommodation ( Mo & Davis, 1997 a ). In order to understand the underlying ionic basis of these characteristic firing patterns, we used α-dendrotoxin (α-DTX) to eliminate the contribution of a class of voltage-gated K+ channels and assessed its effects on a variety of electrophysiological properties by using the whole-cell configuration of the patch-clamp technique. Exposure to α-DTX caused neurons that initially displayed rapid accommodation to fire continuously during 240 ms depolarizing test pulses within a restricted voltage range. We found a non-monotonic relationship between number of action potentials fired and membrane potential in the presence of α-DTX that peaked at voltages between –40 to –10 mV and declined at more depolarized and hyperpolarized test potentials. The α-DTX-sensitive current had two components that activated in different voltage ranges. Analysis of recordings made from acutely isolated neurons gave estimated half-maximal activation voltages of –63 and 12 mV for the two components. Because α-DTX blocks the Kv1.1, Kv1.2 and Kv1.6 subunits, we examined the action of the Kv1.1-selective blocker dendrotoxin K (DTX-K). We found that this antagonist reproduced the effects of α-DTX on neuronal firing, and that the DTX-K-sensitive current also had two separate components. These data suggest that the transformation from a rapidly adapting to a slowly adapting firing pattern was mediated by the low voltage-activated component of DTX-sensitive current with a potential contribution from the high voltage-activated component at more depolarized potentials. In addition, the effects of DTX-K indicate that Kv1.1 subunits are important constituents of the underlying voltage-gated potassium channels. 相似文献
108.
K L Davis L E Hollister A A Mathé B M Davis A B Rothpearl K F Faull J Y Hsieh J D Barchas P A Berger 《The American journal of psychiatry》1981,138(12):1555-1562
The authors performed dexamethasone suppression tests (DST), TRH infusions, 72-hour urine collections, and lumbar punctures on a group of male depressed patients. Approximately 60% of the patients were DST positive and 33% had a blunted TSH response. Two biologic variables, the 8 a.m. postdexamethasone cortisol and the postprobenecid CSF 5-hydroxyindoleacetic acid (5-HIAA), accounted for over half of the variance in the behavioral measure, the Hamilton score. Plasma cortisol elevation was associated with high 3-methoxy-4-hydroxyphenyl glycol (MHPG) excretion; TSH blunting was associated with low urinary MHPG excretion. Comprehensive biologic measures showed certain significant interrelationships and correlations with the severity of depression. 相似文献
109.
Retrorenal colon: implications for percutaneous diskectomy 总被引:1,自引:0,他引:1
It has been recommended that computed tomography (CT) with the patient prone be performed in every patient undergoing percutaneous diskectomy; this would enable detection of a retrorenal location of the colon, which could interfere with the percutaneous procedure. In this evaluation of 346 prone CT studies, only one patient (0.29%) was found to have retrorenal or retropsoas bowel that would have been perforated at diskectomy. Because of this extremely low prevalence, the performance of prone CT in every patient undergoing percutaneous lumbar diskectomy is not believed to be necessary. 相似文献
110.
Water-suppressed 1H magnetic resonance spectra were recorded from two brain regions of psychiatric patients and normal volunteers. The two regions studied were (a) the basal ganglia structures surrounding the anterior horn of the lateral ventricle and (b) the occipital cortex. N-Acetylaspartate (NAA), phosphocreatine-creatine (PCr-Cr), choline and inositol resonances were seen in both regions. Ratios of metabolite peak integrals to PCr-Cr peak integral were calculated for each spectrum. To control for partial volume effects, comparisons between patients and controls were made only from identical regions i.e. basal ganglia vs basal ganglia, and likewise for occipital cortex. Metabolite ratios from the occipital region of patients were similar to those from the occipital region of normal subjects. Bipolar patients being treated with lithium had elevated NAA/PCr-Cr in the basal ganglia region when compared to normals. These patients also demonstrated elevated choline/PCr-Cr and inositol/PCr-Cr ratios in the basal ganglia region. 相似文献