全文获取类型
收费全文 | 28454篇 |
免费 | 2358篇 |
国内免费 | 33篇 |
专业分类
耳鼻咽喉 | 346篇 |
儿科学 | 1017篇 |
妇产科学 | 678篇 |
基础医学 | 3420篇 |
口腔科学 | 571篇 |
临床医学 | 3662篇 |
内科学 | 5259篇 |
皮肤病学 | 435篇 |
神经病学 | 2772篇 |
特种医学 | 1040篇 |
外科学 | 3596篇 |
综合类 | 655篇 |
一般理论 | 46篇 |
预防医学 | 3161篇 |
眼科学 | 503篇 |
药学 | 2127篇 |
3篇 | |
中国医学 | 33篇 |
肿瘤学 | 1521篇 |
出版年
2021年 | 397篇 |
2020年 | 234篇 |
2019年 | 347篇 |
2018年 | 416篇 |
2017年 | 299篇 |
2016年 | 361篇 |
2015年 | 408篇 |
2014年 | 612篇 |
2013年 | 924篇 |
2012年 | 1176篇 |
2011年 | 1322篇 |
2010年 | 748篇 |
2009年 | 550篇 |
2008年 | 1162篇 |
2007年 | 1275篇 |
2006年 | 1273篇 |
2005年 | 1191篇 |
2004年 | 1190篇 |
2003年 | 1025篇 |
2002年 | 965篇 |
2001年 | 963篇 |
2000年 | 975篇 |
1999年 | 772篇 |
1998年 | 285篇 |
1997年 | 273篇 |
1996年 | 240篇 |
1995年 | 243篇 |
1994年 | 216篇 |
1992年 | 689篇 |
1991年 | 705篇 |
1990年 | 656篇 |
1989年 | 604篇 |
1988年 | 599篇 |
1987年 | 554篇 |
1986年 | 567篇 |
1985年 | 540篇 |
1984年 | 425篇 |
1983年 | 418篇 |
1982年 | 271篇 |
1981年 | 255篇 |
1980年 | 230篇 |
1979年 | 424篇 |
1978年 | 309篇 |
1977年 | 266篇 |
1976年 | 240篇 |
1975年 | 230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 15 毫秒
91.
Larry E. Davis Mario Kornfeld Herbert S. Mooney Kurt J. Fiedler Kathleen Y. Haaland William W. Orrison Elsa Cernichiari Thomas W. Clarkson 《Annals of neurology》1994,35(6):680-688
For 3 months in 1969 a family in the United States that included a pregnant mother consumed pork containing methylmercury. Children, aged 20, 13, and 8 years and a neonate, developed severe neurological signs. Twenty-two years later, the 2 oldest had cortical blindness or constricted visual fields, diminished hand proprioception, choreoathetosis, and atentional deficits. Magnetic resonance images showed tissue loss in the calcarine and parietal cortices and cerebellar folia. The youngest had quadriplegia, blindness, and severe mental retradation until their deaths. The brain of the 8-year-old who died at age 30 showed cortical atrophy, neuronal loss, and gliosis, most pronounced in the paracentral and parietooccipital regions. The total mercury level in formalin-fixed, left occipital cortex was 1,974 ng/gm as measured by atomic absorption. Regional brain mercury levels correlated with extent of brain damage. A control patient had 38.5 ng of mercury/gm in the occipital cortex. Systemic organs in the patient and a control subject had comparable mercury levels. In mercury-intoxicated rats, we found that only 5 to 10% of total brain mercury was lost by formalin fixation. Brain inorganic mercury in the patient ranged from 82 to 100%. Since inorganic mercury crosses the blood-brain barrier poorly, biotransformation of methyl to inorganic mercury may have occurred after methylmercury crossed the blood-brain barrier, accounting for its persistence in brain and causing part of the brain damage. 相似文献
92.
Role of frozen section and clinical parameters in distinguishing benign from malignant follicular neoplasms of the thyroid. 总被引:2,自引:0,他引:2
The determination of malignancy preoperatively or intraoperatively is difficult in patients with follicular neoplasms of the thyroid. This study reviews a series of 395 patients treated for follicular neoplasms at the Vancouver General Hospital and the British Columbia Cancer Agency between the years of 1955 and 1988, 198 of whom had frozen section at the time of surgery. Frozen section was 79% accurate in differentiating follicular adenomas from carcinomas, with a sensitivity of 52% and a specificity of 100%. The positive predictive value of a frozen section showing carcinoma was 100%, and the negative predictive value was 73%. An incorrect diagnosis of a benign lesion was made in 21% of patients in whom the final diagnosis by fixed section was carcinoma. These same statistics were calculated for patients aged greater than 50 years, tumor size greater than 3 cm, and patients with a history of previous neck irradiation, three clinical factors shown in a previous study to be strong prognostic indicators of malignancy. The results were compared with those found by frozen section. The implications of these results in terms of patient management are discussed. 相似文献
93.
94.
The rates of incorporation of [3H]choline and [3H]ethanolamine into membrane phospholipids of platelets from 22 drug-free Alzheimer's disease patients and 18 normal elderly controls were compared. No significant differences between groups were found. If alterations in lipid metabolism are involved in the pathophysiological processes underlying Alzheimer's disease, such alterations are not manifest in measures of radiolabeled base incorporation into platelet phospholipids. 相似文献
95.
96.
C E Davis J L Carpenter S Trevino J Koch A J Ognibene 《Diagnostic microbiology and infectious disease》1987,8(3):149-155
In vitro agar dilution susceptibility studies were performed utilizing 20 isolates (24 against rifamycin) of Mycobacterium avium complex against several antimicrobial agents not routinely tested in the mycobacteriology laboratory. Thirteen strains were susceptible to gentamicin at 4 micrograms/ml, 20 to amikacin at 8 micrograms/ml, 18 to streptomycin at 8 micrograms/ml, 20 to kanamycin at 8 micrograms/ml, 20 to trimethoprim/sulfamethoxazole at 2 micrograms/ml, 12 to sulfisoxazole at 10 micrograms/ml, 14 to rifabutin at 1 microgram/ml. No activity was found with penicillin G, cephapirin, moxalactam, vancomycin, clindamycin, erythromycin, trimethoprim, or minocycline. This data suggests a potential use of trimethoprim/sulfamethoxazole, sulfisoxazole, amikacin, gentamicin, and kanamycin in the treatment of infections caused by this group of organisms. 相似文献
97.
Acute myelocytic leukemia and prior allergies 总被引:1,自引:0,他引:1
R K Severson S Davis D B Thomas R G Stevens L Heuser L E Sever 《Journal of clinical epidemiology》1989,42(10):995-1001
The relationship between prior allergies and adult acute myelocytic leukemia was investigated in a population-based case-control study. Based on data from personal interviews of 98 cases and 133 controls, a history of any type of allergy was associated with a significantly decreased risk of acute myelocytic leukemia (OR = 0.35, 95% CI = 0.20-0.60). Risk declined with the total number of specific allergies reported (p less than 0.001), and was reduced in relation to a history of prior asthma, eczema and hives. The implications of these findings in relation to natural immune surveillance against developing neoplasms are discussed. 相似文献
98.
99.
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
100.
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