全文获取类型
收费全文 | 339928篇 |
免费 | 22728篇 |
国内免费 | 7552篇 |
专业分类
耳鼻咽喉 | 4077篇 |
儿科学 | 9549篇 |
妇产科学 | 6561篇 |
基础医学 | 27575篇 |
口腔科学 | 7996篇 |
临床医学 | 37245篇 |
内科学 | 42656篇 |
皮肤病学 | 4583篇 |
神经病学 | 19456篇 |
特种医学 | 7885篇 |
外国民族医学 | 31篇 |
外科学 | 36463篇 |
综合类 | 50824篇 |
现状与发展 | 12篇 |
一般理论 | 32篇 |
预防医学 | 35269篇 |
眼科学 | 5302篇 |
药学 | 30185篇 |
377篇 | |
中国医学 | 30571篇 |
肿瘤学 | 13559篇 |
出版年
2023年 | 5475篇 |
2022年 | 9684篇 |
2021年 | 13215篇 |
2020年 | 12353篇 |
2019年 | 18116篇 |
2018年 | 15830篇 |
2017年 | 12746篇 |
2016年 | 10249篇 |
2015年 | 9585篇 |
2014年 | 19713篇 |
2013年 | 21242篇 |
2012年 | 18114篇 |
2011年 | 19619篇 |
2010年 | 15753篇 |
2009年 | 14480篇 |
2008年 | 14090篇 |
2007年 | 14560篇 |
2006年 | 12692篇 |
2005年 | 11035篇 |
2004年 | 8986篇 |
2003年 | 7911篇 |
2002年 | 6207篇 |
2001年 | 5569篇 |
2000年 | 4603篇 |
1999年 | 4012篇 |
1998年 | 3259篇 |
1997年 | 3109篇 |
1996年 | 2684篇 |
1995年 | 2585篇 |
1994年 | 2498篇 |
1993年 | 1990篇 |
1992年 | 2025篇 |
1991年 | 1746篇 |
1990年 | 1553篇 |
1989年 | 1386篇 |
1988年 | 1316篇 |
1987年 | 1132篇 |
1985年 | 3792篇 |
1984年 | 4800篇 |
1983年 | 3345篇 |
1982年 | 3806篇 |
1981年 | 3551篇 |
1980年 | 3162篇 |
1979年 | 2908篇 |
1978年 | 2537篇 |
1977年 | 1909篇 |
1976年 | 2150篇 |
1975年 | 1634篇 |
1974年 | 1430篇 |
1973年 | 1279篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
991.
We report a newly developed MR simulation system for intracavitary brachytherapy for cervical cancer and subsequent treatment results. MR simulation was performed on six patients. The spatial relationship of the tumor to the bladder, rectum, bowel, applicators, etc. was depicted well. Doses to the tumor and surrounding normal tissues were read from isodose curves superimposed on the T2-weighted sagittal image. This system promises to be useful in customizing the dose distribution. 相似文献
992.
Emilio Bombardieri Antonia Martinetti Rosalba Miceli Luigi Mariani Maria Rita Castellani Ettore Seregni 《European journal of nuclear medicine and molecular imaging》1997,24(11):1349-1355
Bone scintigraphy plays a major role in the diagnosis of bone metastases. The clinical utility of new biochemical markers
of bone metabolism has recently been investigated in various bone diseases. This study evaluated the role of some bone metabolism
markers in comparison with bone scan in the follow-up of breast cancer patients. We studied 149 patients with breast cancer,
33 (22%) of whom had bone metastases. IRMAs were used for the evaluation of blood levels of osteocalcin, bone alkaline phosphatase
(BAP), the C-terminal propeptide of type I procollagen and the C-terminal cross-linked telopeptide of type I collagen (ICTP).
Multivariate regression analysis showed that menopausal status (P=0.007) and metastatic bone lesions (P=0.001) affected bone marker levels. When considering post-menopausal women, the only subset in which bone metabolism marker
behaviour could be reliably investigated, we found a high degree of overlap in marker distribution for scan-positive and scan-negative
patients. Discrimination between scan-negative and scan-positive patients based on the above markers, taken singly or jointly,
was assessed by means of logistic discriminant analysis. The best discrimination was achieved with BAP, closely followed by
ICTP. BAP and ICTP together gave a slight improvement over the use of the two markers separately. However, even in this case
the degree of discrimination was poor and its clinical utility was limited. In fact, to achieve a specificity of 95%, the
sensitivity of the test was about 20%; conversely, with a sensitivity of 95%, the specificity was below 10%. In conclusion,
based on our findings, we believe that blood levels of the investigated markers cannot replace bone scintigraphy in the follow-up
of breast cancer patients for the early detection of bone metastases.
Received 14 April and in revised form 5 July 1997 相似文献
993.
Richard C. Semelka Nikolaos L. Kelekis Gesine John Susan M. Ascher Derek Burdeny Evan S. Siegelman 《Journal of magnetic resonance imaging : JMRI》1997,7(1):153-156
The objective of this study was to demonstrate the appearance of ampullary carcinoma using current MR techniques, including fat suppression, gadolinium enhancement, and MR cholangiography. Nine patients with ampullary carcinoma were examined by MRI at 1.5 T. MR examinations included T1-weighted spoiled gradient echo, T1-weighted fat-suppressed, and immediate postgadolinium spoiled gradient echo images for all patients and MR cholangiography for three patients. The imaging features of ampullary carcinomas, including tumor size and morphology, signal intensity, and enhancement characteristics, were determined. Ampullary carcinomas shown on MR images ranged in size from 1.5 to 5.5 cm. Tumors were low in signal intensity on precontrast T1-weighted spoiled gradient echo and T1-weighted fat-suppressed images relative to normal pancreatic tissue and enhanced less than normal pancreas on immediate postgadolinium spoiled gradient echo images. Tumor conspicuity was greatest on immediate postgadolinium spoiled gradient echo images. MR cholangiography demonstrated high grade obstruction of the common bile duct and mild dilatation of the pancreatic duct at the level of the ampulla with abrupt termination of the ducts in two untreated patients and moderate dilatation of the common bile duct in one patient who had a biliary stent. Ampullary carcinomas can be demonstrated on MR images as small masses arising at the ampulla. Tumors are well defined on immediate postgadolinium spoiled gradient echo images. 相似文献
994.
S Kimel L O Svaasand M Hammer-Wilson V Gottfried S Cheng E Svaasand M W Berns 《Lasers in surgery and medicine》1992,12(4):432-440
The chick chorioallantoic membrane (CAM) model was used to study vascular effects of photodynamic therapy (PDT) and hyperthermia (HPT) and the synergism of these modalities. The CAM is a convenient medium for monitoring the modifications of the vasculature. It is possible to view the CAM and to examine structural changes of individual blood vessels in real time. Moreover, the CAM is a closed system which lends itself to mathematical modeling of the temporal and spatial temperature profile and in which HPT can be performed quantitatively and to a selected depth, using different lasers. A porphyrin-type photosensitizer solution was applied to areas of the CAM, defined by teflon O-rings placed on the surface. Uptake dynamics of the sensitizer into the CAM was determined by analyzing its fluorescence in vivo. The CAM area was irradiated with a dual-wavelength laser system composed of a dye laser at 644 nm (to induce PDT) and a CO2 laser at 10.6 microns (to bring about HPT). Damage to the CAM vasculature, due to combined PDT+HPT, was compared to the outcome of the separate modalities, and a synergistic effect of about 40% was observed. 相似文献
995.
Wataru Kimura 《Journal of hepato-biliary-pancreatic sciences》2003,10(2):156-162
The differences and similarities between intraductal papillary mucinous tumor (IPMT) and mucinous cystadenoma or carcinoma (mucinous cystic tumor; MCT) of the pancreas have been noted. The similarities include: (1) both tumors originate from pancreatic duct cells, (2) massive mucin production is found in both tumors, and (3) papillary projection is a common histological characteristic. However, there are also many differences. IPMT is most frequently found in men in their sixties, and originates in the head of the pancreas, with 62% (123/199) of tumors reported to be found in the head of the pancreas. This tumor sometimes spreads throughout the entire pancreas. The tumor itself basically is of the dilated pancreatic duct type, and the prognosis is generally good. In contrast, MCT frequently develops in women in their forties. This tumor is usually large, round, and almost totally encapsulated by fibrous tissue, with no communication with the pancreatic duct. The tumor histologically has an ovarian-like stroma. It most often develops in the body or tail of the pancreas. Invasion is often present and the operative prognosis is not good. IPMT resembles the shape of a bunch of grapes and MCT resembles that of an orange. From the differences between these two types of tumors, they are classified into different categories. With regard to therapeutic strategies for MCT, the tumor should be resected with lymph node dissection immediately when it is detected. In contrast, some patients with branch-type IPMT can be followed without surgical procedures. Because IPMT shows good prognosis and little tendency for infiltration, some kinds of organ-preserving procedures would be possible for some patients with this tumor. Such organ-preserving procedures are: duodenum-preserving pancreas head resection, spleen-preserving distal pancreatectomy with conservation of the splenic artery and vein, and so on. 相似文献
996.
997.
医院统计在医院要素分配中的作用 总被引:4,自引:2,他引:2
目的 为支持医院内部要素分配调整改革,医院统计应展开与要素分配有关的项目进行统计,为医院要素分配向高、精、尖、绩效好的医务人员倾斜提供统计数据。方法 应用ExCEL软件的合并功能对病人信息和病案信息进行深层次的挖掘、提取、重新整合统计,制成简明易懂的统计报表给予反馈公布,作为医师提取个人奖酬、职称晋升或聘任竞岗的考核依据。结果通过统计作用实现了劳动价值创造,调动了广大医务人员的积极性,促使医院经营理念成为引导个人自觉行为的杠杆,实现了医院提高综合竞争实力的整体效应。结论 要素分配中统计工作应遵循公平、合理、反映医院经营理念的原则和利用网络科技实现高效管理并且应与改革同步,深化统计内涵,完善医院的统计方法。 相似文献
998.
999.
用高效液相色谱跟踪2-甲基-7-亚甲基-1,4,6-三氧螺[4,4]壬烷(MMTN)与丙烯腈(AN),丙烯酸甲酯(MA)的共聚合反应。根据Lowry-Meyer共聚积分方程式,采用插值法进行数据拟合测定单体的竞聚率。对于体系MMTN(M_1)-AN(M_2),r_1=0.048;r_2=0.213;MMTN(M_1)-MA(M_2)r_1=0.025,r_2=0.764。说明两组共聚体系均有较强的交替共聚趋势。 相似文献
1000.
James F. Meschia MD Robert M. Pascuzzi MD José Biller MD 《Journal of stroke and cerebrovascular diseases》1997,6(6):434-435
Limited randomized clinical trial data favor the use of anticoagulation in patients with cerebral venous thrombosis. We present a patient with deep cerebral venous thrombosis in whom anticoagulation was withheld because of coexistent intraventricular hemorrhage. She had a benign clinical course without anticoagulation, suggesting that close observation may be a management option in these patients. 相似文献