全文获取类型
收费全文 | 337903篇 |
免费 | 22500篇 |
国内免费 | 7503篇 |
专业分类
耳鼻咽喉 | 4063篇 |
儿科学 | 9523篇 |
妇产科学 | 6541篇 |
基础医学 | 27428篇 |
口腔科学 | 7919篇 |
临床医学 | 37034篇 |
内科学 | 42460篇 |
皮肤病学 | 4559篇 |
神经病学 | 19261篇 |
特种医学 | 7825篇 |
外国民族医学 | 31篇 |
外科学 | 36329篇 |
综合类 | 50432篇 |
现状与发展 | 12篇 |
一般理论 | 29篇 |
预防医学 | 34823篇 |
眼科学 | 5264篇 |
药学 | 29998篇 |
372篇 | |
中国医学 | 30542篇 |
肿瘤学 | 13461篇 |
出版年
2023年 | 5426篇 |
2022年 | 9643篇 |
2021年 | 13139篇 |
2020年 | 12277篇 |
2019年 | 18038篇 |
2018年 | 15759篇 |
2017年 | 12667篇 |
2016年 | 10171篇 |
2015年 | 9503篇 |
2014年 | 19570篇 |
2013年 | 21089篇 |
2012年 | 17988篇 |
2011年 | 19485篇 |
2010年 | 15646篇 |
2009年 | 14364篇 |
2008年 | 13995篇 |
2007年 | 14468篇 |
2006年 | 12615篇 |
2005年 | 10969篇 |
2004年 | 8930篇 |
2003年 | 7849篇 |
2002年 | 6159篇 |
2001年 | 5534篇 |
2000年 | 4574篇 |
1999年 | 3974篇 |
1998年 | 3221篇 |
1997年 | 3079篇 |
1996年 | 2666篇 |
1995年 | 2568篇 |
1994年 | 2477篇 |
1993年 | 1973篇 |
1992年 | 2006篇 |
1991年 | 1728篇 |
1990年 | 1539篇 |
1989年 | 1370篇 |
1988年 | 1301篇 |
1987年 | 1120篇 |
1985年 | 3785篇 |
1984年 | 4795篇 |
1983年 | 3339篇 |
1982年 | 3800篇 |
1981年 | 3545篇 |
1980年 | 3156篇 |
1979年 | 2904篇 |
1978年 | 2534篇 |
1977年 | 1906篇 |
1976年 | 2149篇 |
1975年 | 1631篇 |
1974年 | 1429篇 |
1973年 | 1277篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
981.
谢林 《湖南中医药大学学报》1994,14(2):1-3
本文从髌骨软骨软化症的病因病理出发,阐述了活血化瘀疗法治疗髌骨软骨软化症的作用及其原理,列举了活血化瘀法在该病治疗中的具体运用,同时强调了在辨证施治基础上活血化瘀的重要性。 相似文献
982.
Kurtis W. Andrews David A. Savitz Irva Hertz-Picciotto 《American journal of industrial medicine》1994,26(1):13-32
Although the adverse effect on pregnancy outcomes at high levels of lead exposure in the workplace has been recognized for years, there is uncertainty regarding the impact of exposure at the lower community exposure levels commonly encountered today. This review summarizes the epidemiologic literature and discusses pertinent methodologic issues and possible sources of interstudy variation. The authors conclude that prenatal lead exposure is unlikely to increase the risk of premature membrane rupture but does appear to increase the risk of preterm delivery. Whether prenatal lead exposure decreases gestational age in terms of infants is unclear. Prenatal lead exposure also appears to be associated with reduced birth weight, but results vary in relation to study design and degree of control for confounding. Adjustment for gestational age, a possible confounder of the birth weight-lead exposure association, did not yield clearer results. 相似文献
983.
We present a patient with vertebrobasilar insufficiency, with vertigo and horizontal nystagmus, induced by turning the head to the right. Angiography demonstrated transient occlusion of the left vertebral artery at the atlantoaxial joint during rotation of the head. The pathogenesis and angiographic findings are discussed. 相似文献
984.
We describe how adverse drug reactions (ADRs) can play an important role in pharmaceutical research and drug development. Not only do ADRs represent the risks and drawbacks associated with drugs but they can also be related to other knowledge available in pharmaceutical and medical research. We offer a model that can be used to systematically map the pathways through which ADRs can lead to innovative research. These pathways include chemical, therapeutic or pathophysiological steps that can be taken to arrive at new knowledge based on ADRs. We used the development of angiotensin-converting enzyme inhibitors, especially captopril, as a case study. The similarity between the ADR profiles of captopril and penicillamine was a starting point for further innovation. Historical analysis shows that in several instances research in the field of angiotensin-converting enzyme inhibitors has been triggered by ADRs. The model presented here might be applicable to other areas of innovative drug research. 相似文献
985.
人大肠癌细胞体外常温及温热环境中药物敏感性试验 总被引:1,自引:0,他引:1
用MTT比色法对20例大肠癌患者术后标本在常温及温热环境中进行体外药物敏感性试验,结果显示,某些药物在温热环境中,对癌细胞的杀伤作用有显著提高,此项试验为临床温热化疗法提供了理论依据。 相似文献
986.
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
987.
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
988.
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
989.
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
990.
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