全文获取类型
收费全文 | 13147篇 |
免费 | 968篇 |
国内免费 | 118篇 |
专业分类
耳鼻咽喉 | 94篇 |
儿科学 | 442篇 |
妇产科学 | 404篇 |
基础医学 | 1780篇 |
口腔科学 | 271篇 |
临床医学 | 1136篇 |
内科学 | 2541篇 |
皮肤病学 | 211篇 |
神经病学 | 920篇 |
特种医学 | 460篇 |
外科学 | 2278篇 |
综合类 | 615篇 |
一般理论 | 4篇 |
预防医学 | 726篇 |
眼科学 | 343篇 |
药学 | 740篇 |
1篇 | |
中国医学 | 78篇 |
肿瘤学 | 1189篇 |
出版年
2023年 | 134篇 |
2022年 | 183篇 |
2021年 | 340篇 |
2020年 | 235篇 |
2019年 | 306篇 |
2018年 | 334篇 |
2017年 | 263篇 |
2016年 | 289篇 |
2015年 | 348篇 |
2014年 | 442篇 |
2013年 | 541篇 |
2012年 | 858篇 |
2011年 | 915篇 |
2010年 | 547篇 |
2009年 | 472篇 |
2008年 | 722篇 |
2007年 | 683篇 |
2006年 | 711篇 |
2005年 | 701篇 |
2004年 | 670篇 |
2003年 | 593篇 |
2002年 | 552篇 |
2001年 | 518篇 |
2000年 | 411篇 |
1999年 | 351篇 |
1998年 | 114篇 |
1997年 | 111篇 |
1996年 | 91篇 |
1995年 | 85篇 |
1994年 | 65篇 |
1993年 | 53篇 |
1992年 | 162篇 |
1991年 | 149篇 |
1990年 | 161篇 |
1989年 | 158篇 |
1988年 | 132篇 |
1987年 | 139篇 |
1986年 | 108篇 |
1985年 | 86篇 |
1984年 | 53篇 |
1983年 | 44篇 |
1981年 | 34篇 |
1980年 | 29篇 |
1979年 | 52篇 |
1978年 | 37篇 |
1977年 | 32篇 |
1976年 | 26篇 |
1975年 | 25篇 |
1974年 | 21篇 |
1973年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
181.
Doppler sonographic detection of reverse twin-twin transfusion after intrauterine death of the donor
We report a "stuck" twin, in which a reverse blood shunt from the recipient to the donor was detected by Doppler sonography after death of the donor. This acute reverse transfusion caused intrauterine fetal distress and severe neonatal anemia of the surviving recipient. We believe that acute hemodynamic change after death of one fetus, in addition to causing a derangement in coagulation, causes immediate danger or subsequent organ damage for the surviving co-twin. 相似文献
182.
Forty-two heroin addicts and 31 normal persons were examined for the effect of acupuncture and electrical stimulation (AES) on plasma ACTH, cortisol and cyclic-AMP levels. Both ACTH and cortisol levels were reduced significantly in the addicts after treatment whereas no such significant reduction was observed in the normals. Plasma cyclic-AMP level was not affected in either group. Taken together, results from the present study suggest that the mechanism of AES in the treatment of addiction may have a neuroendocrinological basis. This hypothesis is particularly attractive in view of the isolation of opiate-like peptides from the brain. 相似文献
183.
The dopamine-beta-hydroxylase inhibitor, FLA-57, was reported by several investigators to reduce voluntary ethanol consumption in rats. The nature of the effect of FLA-57 on this behavior had been attributed to its involvement in both the mediation of positive reinforcing and aversive processes. In the present study, the capacity of FLA-57 to induce a conditioned taste aversion (CTA) in both a forward and a "nominally backward conditioning" paradigms was investigated. This was done in an attempt to assess the possible contribution of a FLA-57-induced CTA to the previously observed reduction in ethanol intake in several drinking studies. Furthermore, the ability of FLA-57 to induce a CTA in a nonnovel situation, where the taste of the presented solution (ethanol or saccharin) was familiar to the animals, was also assessed. The inclusion of these specific conditions was necessitated by the attempt to create conditions similar to those prevalent in drinking studies. We found that FLA-57, in both conditioning paradigms, induced a significant CTA. Animals, naive and experienced with the taste of ethanol or saccharin, exhibited a CTA following the administration of FLA-57. However, the magnitude and rate of extinction of the observed CTAs did not resemble those observed in studies on the effects of FLA-57 on ethanol intake. The results of this study suggest that while it is possible that FLA-57 exerts its effect on ethanol intake, at least in part, through an aversive mechanism, such a mechanism is unlikely to be the exclusive process through which ethanol ingestion is attenuated. 相似文献
184.
185.
Automated noninvasive blood pressure (NIBP) monitors have found widespread use both inside and outside clinical environments in recent years. Present methods for evaluating the measurement accuracy of this class of devices involve population studies that are meticulous, time-consuming and costly. These methods are also impractical for routine evaluation. NIBP simulators offer an alternative approach to evaluating automated NIBP monitors without directly using human subjects. They enable evaluation to be carried out on demand with little training, providing a safe and convenient way for manufacturers and hospitals to validate the performance of both new and existing monitors. 相似文献
186.
187.
双能量X线骨质密度测量仪监测小儿下肢骨延长骨矿物质的变化 总被引:1,自引:0,他引:1
目的 在儿童骨延长的患儿中 ,为了能够有效地控制骨延长的速率 ,达到骨延长的目的 ,采用双能量X线骨质密度测量仪 (dualenergyX Rayabsorptiometry ,DEXA)监测延长断端骨矿含量 (bonemineralcontent,BMC)的变化。方法 30例患儿中有 5 0处下肢作了骨延长术 ,平均年龄10 .9岁 (5~ 17岁 ) ,引起短肢的病因不同。术后 7~ 10d开始行骨延长 ,每次延长 0 .2 5mm ,每天 4次。牵引延长期间每周扫描一次 ,拆除外固定器后每 2周扫描一次到术后 2年。DEXA扫描的分辨率是 1mm× 1mm ,扫描速度 30mm/s。比较不同延长时期中骨矿含量的变化。分析不同病因和不同外固定器之间骨矿含量变化的差别。结果 不同固定器之间骨矿含量的差别无著性意义。根据骨延长区BMC增加速率 ,将患儿分为快速组、一般组和慢速组。快速组每日BMC增加速率为 0 .3%~ 0 .6 % ,新骨生长快速 ;一般组每日BMC增加 0 .1%~ 0 .3% ,新骨中速生长 ;慢速组每日增加 <0 .1% ,新骨生成缓慢。骨矿化速率与原发病因相关。结论 DEXA能动态监测骨延长中新生骨的骨矿含量的变化 ,根据骨矿含量变化的程度 ,能够调整骨延长的速率 ,从而达到预期骨延长的目的。 相似文献
188.
Prostatic neoplasia in transgenic mice with prostate-directed overexpression of the c-myc oncoprotein 总被引:3,自引:0,他引:3
BACKGROUND: Promoter elements within the 5' DNA region of the rat C(3)1 gene have been shown to direct prostate-specific expression of gene products when they are fused through recombinant DNA procedures and used to produce transgenic mice. In order to test the in vivo effects of chronic overexpression of the mouse c-myc protooncogene on the prostate glands of transgenic mice, we created several lines of C(3)1-c-myc transgenic mice and then examined the phenotype of males with this genetic alteration. METHODS: The modified promoter and 5' region of the rat C(3)1 gene was fused to the coding region of the mouse c-myc gene using recombinant DNA techniques. This DNA was used to create three different founder lines of transgenic mice. Tissues from males and females heterozygous for the transgene were examined for expression of the recombinant mouse c-myc mRNA by an RNase protection assay. Prostates from males were examined for expression of recombinant c-myc mRNA by in situ hybridization. Thin sections of fixed ventral prostates from males were analyzed by microscopy for histological abnormalities. RESULTS: Three different lines of transgenic mice were obtained from these procedures. These mice demonstrated expression of recombinant mouse c-myc mRNA in the testis and ventral prostates of males and in the uterus of females. In situ hybridization demonstrated that the epithelial cells were the source of recombinant c-myc expression in the ventral prostates of the transgenic lines. Microscopic analysis of the ventral prostates from these mice demonstrated abnormalities in epithelial cell morphology seemingly typical of an intraepithelial neoplasia-like phenotype. However, none of the males of any of the lines developed overt prostatic adenocarcinoma over their lifetimes. CONCLUSIONS: Chronic overexpression of c-myc in the ventral prostate epithelial cells of C3(1)-c-myc transgenic mice leads to the development of epithelial cell abnormalities similar to those seen in low-grade prostatic intraepithelial neoplasia in humans. These abnormalities were not found to progress to adenocarcinoma over the lifetimes of the transgenic mice, suggesting the need for additional oncogenic changes in the pathway to prostatic adenocarcinomas. Furthermore, our cumulative experience with the use of the C3(1) gene promoter in the generation of transgenic mice suggests that the probasin promoter element provides a much more specific and effective means to target transgenes to the prostate glands of mice. 相似文献
189.
Siow WY Yip SK Ng LG Tan PH Cheng WS Foo KT 《Journal of the Royal College of Surgeons of Edinburgh》2000,45(5):291-295
In developed countries, there has been increased incidental detection of renal cell carcinoma (RCC). The incidence, pathological stage and survival of incidentally detected carcinoma in a developing country in Asia where, from 1990 to 1998, 165 renal cell carcinomas were identified. The clinical presentation, diagnostic-imaging modality employed, pathological staging and patient survival was reviewed. Incidental renal cancers included those that were diagnosed through health screening or detected incidentally through imaging studies for other conditions. The survival between these incidentally detected lesions and their symptomatic counterparts (suspected group) was compared. Sixty-four patients (39%) had their tumours detected incidentally, including 39 who were entirely asymptomatic and 25 who presented with non-specific symptoms, not initially suggestive of RCC. For the entire group, computed tomography provided the definitive diagnosis in 81% of cases. The incidental detection group had significantly smaller size of tumour (5.9 cm c.f. 7.6 cm), lower stage and lower histological grading. In particular, 78% of patients with incidental RCC had stage I or II diseases (TNM stage classification), compared with 57% of patients with suspected tumour (p < 0.05; Chi-square test). The disease free survival was significantly better for those with incidental detection (86% c.f. 66% at last follow up; p < 0.05; log-rank test) over a mean follow up period of 33 months (range 1-91). Regression analysis showed that stage of disease was the only independent variable predictive of clinical outcome. In conclusion, that significant numbers of RCC were detected incidentally. These tumours were of a lower clinical pathological stage and had a better prognosis. 相似文献