全文获取类型
收费全文 | 3191篇 |
免费 | 262篇 |
国内免费 | 85篇 |
专业分类
耳鼻咽喉 | 13篇 |
儿科学 | 115篇 |
妇产科学 | 99篇 |
基础医学 | 483篇 |
口腔科学 | 73篇 |
临床医学 | 403篇 |
内科学 | 585篇 |
皮肤病学 | 44篇 |
神经病学 | 220篇 |
特种医学 | 349篇 |
外科学 | 370篇 |
综合类 | 80篇 |
一般理论 | 4篇 |
预防医学 | 262篇 |
眼科学 | 32篇 |
药学 | 224篇 |
中国医学 | 1篇 |
肿瘤学 | 181篇 |
出版年
2022年 | 20篇 |
2021年 | 31篇 |
2020年 | 22篇 |
2019年 | 39篇 |
2018年 | 39篇 |
2017年 | 30篇 |
2016年 | 36篇 |
2015年 | 54篇 |
2014年 | 50篇 |
2013年 | 69篇 |
2012年 | 109篇 |
2011年 | 91篇 |
2010年 | 75篇 |
2009年 | 77篇 |
2008年 | 110篇 |
2007年 | 163篇 |
2006年 | 91篇 |
2005年 | 105篇 |
2004年 | 98篇 |
2003年 | 89篇 |
2002年 | 101篇 |
2001年 | 105篇 |
2000年 | 80篇 |
1999年 | 87篇 |
1998年 | 97篇 |
1997年 | 96篇 |
1996年 | 76篇 |
1995年 | 82篇 |
1994年 | 56篇 |
1993年 | 56篇 |
1992年 | 82篇 |
1991年 | 62篇 |
1990年 | 84篇 |
1989年 | 82篇 |
1988年 | 93篇 |
1987年 | 73篇 |
1986年 | 72篇 |
1985年 | 95篇 |
1984年 | 59篇 |
1983年 | 52篇 |
1982年 | 46篇 |
1981年 | 33篇 |
1980年 | 43篇 |
1979年 | 43篇 |
1978年 | 29篇 |
1977年 | 30篇 |
1976年 | 39篇 |
1975年 | 23篇 |
1972年 | 20篇 |
1969年 | 23篇 |
排序方式: 共有3538条查询结果,搜索用时 31 毫秒
61.
A Orr M Rubillowicz R LeBlanc C Seamone C Mann 《Canadian journal of ophthalmology. Journal canadien d'ophtalmologie》1990,25(3):133-137
We compared the results of suprathreshold testing of the nasal periphery with those of quantitative assessment of the same area. One eye each from 81 patients in four categories (normal [21 subjects], low-risk ocular hypertensive [20 subjects], high-risk ocular hypertensive [20 subjects] and early glaucoma [20 subjects]) was tested with the nasal suprathreshold points of the Octopus G1 program and the Sargon peripheral field-nasal (PFN) program. Simple algorithms were developed to generate from the nasal suprathreshold points of the G1 program two "qualitative indices", mean defect-qualitative (MD-Q) and loss variance-qualitative (LV-Q); these are analogous to the indices mean defect and loss variance respectively, which were calculated from the PFN program data. MD-Q and LV-Q were found to be well correlated with their quantitative counterparts. They provide a uniform method for interpreting the nasal suprathreshold points of the G1 program and help identify patients in whom further quantitative testing is likely to yield useful information. 相似文献
62.
1 临床资料 患者 ,女 ,6 1岁 ,1999- 0 6 - 0 3日确诊为急性红白血病 (M6 ) .先后 4次住院 ,鉴定血型均为 O型 . 2 0 0 0 - 0 1- 2 2日复诊 ,正反鉴定表明 ,患者红细胞与抗 - B不凝集 ,与抗 - A凝集 ,血清中有抗 - B抗体 (表 1) ,吸收释放试验证实为 A型 (表2 ) .输 A型浓缩红细胞 2 μ,无不良反应 .表 1 血型正反鉴定试剂血清试剂红细胞标本抗 A 抗 B 抗 A+ B Ac Bc Oc被检红细胞 2 + -3+ ---自身血清 -3+ -表 2 吸收、放散试验被检 RBC吸收抗血清后上清被检 RBC吸收抗血清后释放液试剂细胞抗 A修正液抗 B修正液抗 A修正液抗… 相似文献
63.
综合疗法治愈狼疮性急性肾衰1例 总被引:3,自引:2,他引:1
1 病例报告 患者 ,女 ,6 0岁 ,因反复发热 2 5 a、全身性关节疼痛 2 3 a,双下肢水肿 2 mo,腹胀、尿少 1mo,于 1998- 10 - 2 0入院 .1975年患者出现发热 ,全身关节疼痛 ,四肢关节周围皮肤出现结节性红斑 ,触之疼痛 ,多次化验血沉 115 mm· h- 1 ,抗核抗体阴性 ,类风湿因子阳性 ,未找到狼疮细胞 ,诊断为“类风湿性关节炎”.1986年因上述症状复发再次入我院 ,多次检查后发现血抗核抗体 ( ) ,抗双链 DNA抗体 ( ) ,临床确诊为系统性红斑狼疮 (SL E) ,狼疮性肝炎 ,狼疮性胸膜炎 ,狼疮性肺炎 .经治疗好转 ,但上述症状反复发作 .此次上述症状复… 相似文献
64.
The aim of this study was to ascertain the status of CuZn superoxide dismutase (CuZn-SOD) expression in the central nervous system of Drosophila melanogaster. Immunoblot analysis of dissected tissue extracts revealed low levels of the CuZn-SOD protein in adult brains relative to other adult and larval tissues. To explore further this observation, three different reporter constructs containing different elements of the CuZn-SOD promoter domain were used for the generation of transgenic flies. A high level of reporter gene expression occurred during the second wave of neurogenesis (third instar and early pupal stages) in scattered, proliferating neuroblasts (NBs) and in proliferation centers of the optic lobe. In mature, postmitotic neurons, this expression was lower relative to other tissues. In adult flies, at all ages examined, there was little if any detectable reporter gene expression in cells of the central nervous system. These results suggest that one of the key components of the antioxidant defenses, CuZn-SOD, is quite low in postmitotic neural tissue, rendering it particularly susceptible to oxidative damage during aging. 相似文献
65.
66.
Patterson LH McKeown SR Robson T Gallagher R Raleigh SM Orr S 《Anti-cancer drug design》1999,14(6):473-486
An ideal cancer chemotherapeutic prodrug is completely inactive until metabolized by a tumour-specific enzyme, or by an enzyme that is only metabolically competent towards the prodrug under physiological conditions unique to the tumour. Human cancers, including colon, breast, lung, liver, kidney and prostate, are known to express cytochrome P450 (CYP) isoforms including 3A and 1A subfamily members. This raises the possibility that tumour CYP isoforms could be a focus for tumour-specific prodrug activation. Several approaches are reviewed, including identification of prodrugs activated by tumour-specific polymorphic CYPs, use of CYP-gene directed enzyme prodrug therapy and CYPs acting as reductases in hypoxic tumour regions. The last approach is best exemplified by AQ4N, a chemotherapeutic prodrug that is bioreductively activated by CYP3A. This study shows that freshly isolated murine T50/80 mammary carcinoma and RIF-1 fibrosarcoma 4-electron reduces AQ4N to its cytotoxic metabolite, AQ4 (T50/80 Km = 26.7 microM, Vmax = 0.43 microM/mg protein/min; RIF-1 Km = 33.5 microM, Vmax = 0.42 microM/mg protein/min) via AQM, a mono-N-oxide intermediate (T50/80 Km = 37.5 microM; Vmax = 1.4 microM/mg protein/min; RIF-1 Km = 37.5 microM; Vmax = 1.2 microM/mg protein/ min). The prodrug conversion was dependent on NADPH and inhibited by air or carbon monoxide. Cyp3A mRNA and protein were both present in T50/80 carcinoma grown in vivo (RIF-1 not measured). Exposure of isolated tumour cells to anoxia (2 h) immediately after tumour excision increased cyp3A protein 2-3-fold over a 12 h period, after which time the cyp protein levels returned to the level found under aerobic conditions. Conversely, cyp3A mRNA expression showed an initial 3-fold decrease under both oxic and anoxic conditions; this returned to near basal levels after 8-24 h. These results suggest that cyp3A protein is stabilized in the absence of air, despite a decrease in cyp3A mRNA. Such a 'stabilization factor' may decrease cyp3A protein turnover without affecting the translation efficiency of cyp3A mRNA. Confirmation of the CYP activation of AQ4N bioreduction was shown with human lymphoblastoid cell microsomes transfected with CYP3A4, but not those transfected with CYP2B6 or cytochrome P450 reductase. AQ4N is also reduced to AQ4 in NADPH-fortified human renal cell carcinoma (Km = 4 microM, Vmax = 3.5 pmol/mg protein/min) and normal kidney (Km = 4 microM, Vmax = 4.0 pmol/mg protein/min), both previously shown to express CYP3A. Germane to the clinical potential of AQ4N is that although both normal and tumour cells are capable of reducing AQ4N to its cytotoxic species, the process requires low oxygen conditions. Hence, AQ4N metabolism should be restricted to hypoxic tumour cells. The isoform selectivity of AQ4N reduction, in addition to its air sensitivity, indicates that AQ4N haem coordination and subsequent oxygen atom transfer from the active-site-bound AQ4N is the likely mechanism of N-oxide reduction. The apparent increase in CYP3A expression under hypoxia makes this a particularly interesting application of CYPs for tumour-specific prodrug activation. 相似文献
67.
Patho-radiologic correlation of invasive pulmonary aspergillosis in the compromised host 总被引:5,自引:0,他引:5
The autopsy findings and antemortem radiographic abnormalities were correlated in 20 patients with invasive pulmonary aspergillosis to define typical radiographic patterns, their progression and anatomic basis. Sixteen (80%) patients had radiographic abnormalities due to aspergillosis. Fifty-nine percent of the specific radiographic abnormalities seen in these patients were caused by anatomic lesions of asperigillosis and 67% of such anatomic lesions were radiographically definable. The most common initial radiographic pattern was a patchy density (single or multifocal) or a well defined nodule. The densities remained stable in half the patients but progressed, over several weeks to either diffuse consolidation or cavitation in the others. Most anatomic lesions were categorized as either nodular ("target") lesions (1-3 cm in diameter) or hemorrhagic infarctions (5-10 cm in diameter), both due to vascular invasion causing thrombosis and ischemic necrosis. Unlike pulmonary candidiasis, which is usually radiographically undetectable, invasive pulmonary asperigillosis frequently caused radiographically visible lesions. 相似文献
68.
Randomized, placebo-controlled study of oregovomab for consolidation of clinical remission in patients with advanced ovarian cancer. 总被引:8,自引:0,他引:8
Jonathan S Berek Peyton T Taylor Alan Gordon Mary J Cunningham Neil Finkler James Orr Saul Rivkin Birgit C Schultes Theresa L Whiteside Christopher F Nicodemus 《Journal of clinical oncology》2004,22(17):3507-3516
PURPOSE: To assess oregovomab as consolidation treatment of advanced ovarian cancer and refine the immunotherapeutic strategy for subsequent study. PATIENTS AND METHODS: Patients with stage III/IV ovarian cancer who had a complete clinical response to primary treatment were randomly assigned to oregovomab or placebo administered at weeks 0, 4, and 8, and every 12 weeks up to 2 years or until recurrence. The primary end-point was time to relapse (TTR). RESULTS: One hundred forty-five patients were treated with oregovomab (n = 73) or placebo (n = 72). For the population overall, median TTR was not different between treatments at 13.3 months for oregovomab and 10.3 months for placebo (P =.71). Immune responses were induced in most actively treated patients. This was associated with prolonged TTR. Quality of life was not adversely impacted by treatment. Adverse events were reported with similar frequency in oregovomab and placebo groups, indicating a benign safety profile. A long-term survival follow-up is ongoing. Cox analysis of relapse data identified significant factors: performance status, CA-125 before third cycle, and baseline CA-125. Further evaluation identified a subpopulation with favorable prognostic indicators designated as the successful front-line therapy (SFLT) population. For the SFLT population, TTR was 24.0 months in the oregovomab group compared with 10.8 months for placebo (unadjusted hazard ratio of 0.543 [95% CI, 0.287 to 1.025]), a hypothesis-generating observation. CONCLUSION: Consolidation therapy with oregovomab did not significantly improve TTR overall. A set of confirmatory phase III studies has been initiated to determine whether the SFLT population derives benefit from oregovomab treatment. 相似文献
69.
WG Mitchell H Lynn JF Bale MA Maeder SM Donfield B Garg AH Tilton JK Willis TP Bohan 《Pediatrics》1997,100(5):817-824
BACKGROUND: Boys and young men with hemophilia treated with factor infusions before 1985 had a substantial risk of acquiring the human immunodeficiency virus (HIV) and the acquired immunodeficiency syndrome. This study was designed to assess the effects of HIV and hemophilia per se on neurological function in a large cohort of subjects with hemophilia, and to investigate the relationships between neurological disease and death during follow-up. METHODS: Three hundred thirty-three boys and young men (207 HIV seropositive and 126 HIV seronegative) were evaluated longitudinally in a multicenter, multidisciplinary study. Neurological history and examination were conducted at baseline and annually for 4 years. The relationship between neurological variables, HIV serostatus, CD4+ cell counts, and vital status at the conclusion of the study was examined using logistic regression models. RESULTS: The risks of nonhemophilia-associated muscle atrophy, behavior change, and gait disturbance increased with time in immune compromised HIV-seropositive subjects compared with HIV seronegative or immunologically stable HIV-seropositive subjects. The risk of behavior change in immune compromised HIV-seropositive hemophiliacs, for example, rose to 60% by year 4 versus 10% to 17% for the other study groups. Forty-five subjects (13.5%), all of whom were HIV seropositive, died by year 4. Subjects who died had had increased risks of hyperreflexia, nonhemophilia-associated muscle atrophy, and behavior change. CONCLUSIONS: These results indicate that immune compromised, HIV-seropositive hemophiliacs have high rates of neurological abnormalities over time and that neurological abnormalities were common among subjects who later died. By contrast, immunologically stable HIV-seropositive subjects did not differ from the HIV-seronegative participants. Hemophilia per se was associated with progressive abnormalities of gait, coordination, and motor function. 相似文献
70.
Dermoid tumours in children usually occur in two locations: at the anterior fontanelle and on the occipital squama. An exceptional site of origin for a posterior fossa dermoid cyst is the extradural space. There are only six previous cases of this situation reported in the literature. A series of 103 subscalp and calvarial masses in children were reviewed and three children are reported with extradural dermoids of the posterior fossa, which communicated with the skin through midline occipital dermal sinuses. All three children were seen after the rapid growth or the formation of an abscess in a previously noted occipital subcutaneous mass present since birth. Although computed tomography or magnetic resonance imaging showed the dermal sinus and the intracranial tumour, these studies were unable to ascertain the intradural or extradural nature of the tumours, their exact origin only being established at operation. Histopathological study showed preclinical signs of infection in the two patients that had not yet formed an abscess. It is suggested that early neurosurgical treatment of these neoplasms should be done to prevent the development of severe intracranial infection. The previously reported simplicity of surgical removal of occipital extradural dermoids was not confirmed in this series. 相似文献