全文获取类型
收费全文 | 42867篇 |
免费 | 3317篇 |
国内免费 | 457篇 |
专业分类
耳鼻咽喉 | 384篇 |
儿科学 | 1260篇 |
妇产科学 | 802篇 |
基础医学 | 6470篇 |
口腔科学 | 587篇 |
临床医学 | 4086篇 |
内科学 | 9319篇 |
皮肤病学 | 953篇 |
神经病学 | 3583篇 |
特种医学 | 1513篇 |
外国民族医学 | 16篇 |
外科学 | 5027篇 |
综合类 | 1296篇 |
现状与发展 | 1篇 |
一般理论 | 4篇 |
预防医学 | 3422篇 |
眼科学 | 784篇 |
药学 | 3149篇 |
6篇 | |
中国医学 | 628篇 |
肿瘤学 | 3351篇 |
出版年
2023年 | 358篇 |
2022年 | 785篇 |
2021年 | 1384篇 |
2020年 | 836篇 |
2019年 | 1049篇 |
2018年 | 1345篇 |
2017年 | 925篇 |
2016年 | 976篇 |
2015年 | 1177篇 |
2014年 | 1541篇 |
2013年 | 1989篇 |
2012年 | 2916篇 |
2011年 | 2916篇 |
2010年 | 1715篇 |
2009年 | 1520篇 |
2008年 | 2212篇 |
2007年 | 2278篇 |
2006年 | 2159篇 |
2005年 | 2109篇 |
2004年 | 1825篇 |
2003年 | 1763篇 |
2002年 | 1603篇 |
2001年 | 1152篇 |
2000年 | 1140篇 |
1999年 | 1045篇 |
1998年 | 423篇 |
1997年 | 359篇 |
1996年 | 304篇 |
1995年 | 253篇 |
1994年 | 242篇 |
1993年 | 197篇 |
1992年 | 530篇 |
1991年 | 512篇 |
1990年 | 484篇 |
1989年 | 433篇 |
1988年 | 458篇 |
1987年 | 385篇 |
1986年 | 378篇 |
1985年 | 372篇 |
1984年 | 264篇 |
1983年 | 191篇 |
1982年 | 121篇 |
1979年 | 213篇 |
1978年 | 115篇 |
1977年 | 125篇 |
1976年 | 113篇 |
1974年 | 131篇 |
1973年 | 107篇 |
1972年 | 129篇 |
1969年 | 104篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
R Bachmann B Genin P Bugmann D Belli S Hanquinet P Liniger C Le Coultre 《Zeitschrift für Kinderchirurgie》2003,13(4):280-284
Although benign, hepatic haemangioendotheliomas (HHE) are rare vascular tumours of the infant which have a high mortality rate secondary to high output congestive heart failure. The management of these tumours is still controversial and none of the different medical or surgical options has been unanimously accepted. We report the case of a neonate with congestive heart failure (CHF) due to a localized HHE, treated successfully by selective ligation of the left hepatic artery branch irrigating the tumour, under perioperative ultrasound Doppler control. A review of the literature showed 35 cases of HHE treated by hepatic artery ligation (HAL) with a survival rate of 80 %. 相似文献
62.
The cyclic vomiting syndrome is defined by episodes of vomiting lasting from hours to days with free intervals between episodes. Various symptoms can be associated with vomiting: nausea, abdominal pain, photophobia, fever, pallor, dehydratation, excess salivation, social withdrawal. Some factors often precipitate the crisis: infection, psychological stresses, menstruation. Excluding a medical condition, especially a gastro-intestinal or a neurological disease is compulsory for the diagnostic of cyclic vomiting syndrome. The cyclic vomiting syndrome shares many common features with migraine including treatment. Due to negative paraclinical testing, a psychiatric disease is often suspected in these children. Pathophysiology of cyclic vomiting syndrome is unknown. As for migraine, mitochondrial and ionic channels abnormalities are thought to play a role. Overactivation of hypothalamic-pituitary-adrenal axis and autonomic dysfunction seem to be involved too. Three clinical vignets will illustrate these aspects. 相似文献
63.
Effects of different cellulose derivatives on drug release mechanism studied at a preformulation stage. 总被引:2,自引:0,他引:2
O Chambin D Champion C Debray M H Rochat-Gonthier M Le Meste Y Pourcelot 《Journal of controlled release》2004,95(1):101-108
As a matter of fact, in vitro dissolution is well known to be the method of choice for the pharmaceutical industry to develop effective medicines. However, many experiments must be performed all along a new product life and they represent an overcharge of work for researchers. The purpose of this paper was to assess the relevance of new parameters obtained during preformulation stage by Nuclear Magnetic Resonance (NMR) experiments to better understand drug release mechanism. This study was carried out with three cellulose derivatives currently used as carrier matrices (Microcrystalline cellulose (MCC), Hydroxypropylmethyl cellulose (HPMC) and Ethyl cellulose (EC)). Granules and tablets were produced with these three excipients (60% w/w) and theophylline as drug model (40%). On the one hand, in vitro dissolution studies were performed with the rotating paddle method displaying the different release behaviour of these three matrices (immediate release for MCC, steady release for HPMC and sustained release for EC). On the other hand, the evolution of the T2m spin-spin relaxation time in NMR experiments during granules hydration was recorded. NMR findings shore up dissolution data, both depending on interactions between the matrix and water. NMR spectroscopy appears to be a valuable tool for obtaining, at an earlier stage of drug development, more information about drug release mechanism. 相似文献
64.
OBJECTIVE: This study analyzed the influence of the acquisition method in image-free computer-assisted total knee arthroplasty (CAS-TKA), and the reproducibility of implant planning using BoneMorphing, a 3D morphometric model obtained by a 3D-to-3D elastic registration of statistical models to sparse point clouds acquired directly on the bone surface with a pointer. MATERIALS AND METHODS: Five surgeons (one expert, four trainees) each performed a CAS-TKA hybrid protocol based on morphometric models and landmarks on a cadaveric knee 10 times. In addition, several additional landmarks were digitized during each acquisition. The reproducibility of the implant positioning and sizing, as determined by an implant planning algorithm with morphometric models, was compared to direct digitization accuracy. RESULTS: Femoral and tibial implant positioning parameters with the hybrid protocol resulted in intra-surgeon standard deviations (SDs) of less than+/-1.4 degrees for rotation and 1.9 mm for translation for all surgeons in all directions except for tibial axial rotation (the only parameter determined by a digitized landmark and not recomputed in the 3D model). The variability in individual landmark digitization varied from 2 to 5 mm SD for certain landmarks, with ranges of 15-25 mm across all surgeons. The comparison study showed an improvement in femoral rotation reproducibility with the morphometric model when using the posterior condylar axis. Tibial implant reproducibility for each method was comparable, with the morphometric model giving better results in well-digitized areas such as the tibial plateau. CONCLUSION: A CAS-TKA protocol based on a deformed statistical model offers reproducible implant positioning. Some landmarks, such as distal condyles, show sufficient reproducibility in the direction of interest, while others, such as the anterior tibial tubercle, can lead to hazardous implant positioning. This should be taken into consideration when designing a CAS-TKA system with bony landmarks. In areas where a sufficient number of points have been digitized with good coverage, such as on the distal and posterior femoral condyles or the tibial plateau areas, the information derived from the 3D model is more accurate and reproducible than that derived from digitization. Good training and a guiding user interface are essential to guarantee coverage quality. 相似文献
65.
G G Varela A López-Loredo J F García León 《JSLS, Journal of the Society of Laparoendoscopic Surgeons》2007,11(1):127-130
BACKGROUND AND OBJECTIVE: We present the case of a female patient 29 years of age with antecedents of laparoscopic laser ablation for endometriosis, laparoscopic appendectomy, and umbilical hernioplasty. METHODS: The patient was admitted to the hospital's emergency room for abdominal pain in the epigastrium, transfixing, irradiating to both upper quadrants and to the lumbar region, accompanied by nausea and gastrobiliary vomiting. Lipase determination was 170 mg/dL. Other laboratory findings were normal. Plain abdominal films on the patient's admission were normal, and computed tomography (CT) showed data compatible with acute pancreatitis. Without improvement during the patient's hospital stay, pain and vomiting increased in intensity and frequency. RESULTS: New abdominal x-rays revealed dilatation of small bowel loops. Management was begun for intestinal obstruction, with intravenous hydration and placement of a nasogastric tube without a good response. At 48 hours, a diagnostic laparoscopy was performed, revealing a 3-cm internal hernia in the left broad ligament in which a 20-cm segment of terminal ileum was encased. We performed liberation of the ileal segment and closed the hernial orifice by using the laparoscopic approach. CONCLUSION: The patient's evolution was excellent. 相似文献
66.
67.
68.
Prospective study of the occurrence of monoclonal gammapathies following bone marrow transplantation in young children 总被引:2,自引:0,他引:2
We have prospectively studied the occurrence of monoclonal serum immunoglobulins in 38 recipients of BMT. Patients were young children with primary immunodeficiencies (n = 31), other inherited diseases (n = 4), leukemia (n = 2), or aplastic anemia (n = 1). Twenty-nine received an HLA-nonidentical marrow and nine an HLA-identical marrow. Serum monoclonal immunoglobulins were detected by the immunofixation method. Monoclonal immunoglobulins were found in 26 patients. Monoclonal components were more frequently detected in patients with primary severe T cell deficiencies (21/25) rather than in the other patients (6/13). In 7 of 29 recipients of HLA-nonidentical transplants, versus 0 out of 9 recipients of HLA-identical transplants, serum monoclonal immunoglobulins were found associated with a B lymphocyte proliferation syndrome due to an Epstein-Barr virus infection. In this group, monoclonal immunoglobulins were detected early, prior to the onset of the clinical syndrome. The simultaneous occurrence of several monoclonal immunoglobulins was more frequent in these patients, while monoclonal immunoglobulin concentrations increased faster, especially those of IgM isotype. These characteristics may allow in patients at risk (recipients with primary T cell immunodeficiencies and receiving HLA-nonidentical transplantation) an earlier diagnosis of B lymphocyte proliferative syndrome that may eventually lead to early and more efficient therapy. 相似文献
69.
D Komiotis C T Lim J P Dieter G C Le Breton D L Venton 《Journal of medicinal chemistry》1992,35(16):3033-3039
Previous observations implicating PgH2 as a direct activator of platelets suggested that derivatives of U46619, a well-characterized TxA2 receptor agonist having structural homology with PgH2, might possess antiplatelet activity. The present work describes the synthesis of [1S-(1 alpha,2 beta,3 alpha,4 alpha)]-3-[(tetrahydropyranyloxy)methyl]- 2-[2-[(triphenylmethyl)oxy]ethyl]-5-oxabicyclo[2.2.1]heptane (14) a potentially useful intermediate for the synthesis of various epoxymethano derivatives. The latter was converted to [1S-(1 alpha,2 beta (Z),3 alpha,4 alpha)]-7-[3-[[2- [(phenylamino)carbonyl]-hydrazino]methyl]-5-oxabicylo[2.2.1]hept-2 - yl]-5-heptenoic acid (23), an epoxymethano derivative of PgH2 containing a hydrazide lower side chain as previously used in the TxA2 antagonist, SQ 29,548. The intermediate 14 was also converted to [1S-(1 alpha,2 beta (Z),3 alpha,4 alpha)]-7- [3-[(hexylamino)methyl]-5-oxabicyclo[2.2.1]hept-2-yl]-5-heptenoic acid (25) which contained a simple aza side chain as used in earlier antagonists. Derivatives 23 and 25 appeared to be specific antagonists of the human platelet TxA2 receptor as evidenced by their inhibition of U46619 (1.5 microM) induced aggregation of human platelet rich plasma (IC50 = 22 and 7 microM, respectively), while having little effect on ADP (2 microM) induced aggregation at much higher concentrations. In addition, one of these derivatives, the bicycloamine 25, was shown to compete for [3H]U46619 binding to washed human platelets with an IC50 value of 25 microM, supporting the notion that these derivatives were acting at the thromboxane receptor. However, the potency of these derivatives was less than for previously reported TxA2 antagonists, suggesting that simple linear combinations of functionality from molecules active at the human platelet thromboxane receptor will be of limited predictive value. 相似文献
70.
Kim Hahn Le Quan Sang Jean-Luc Elghozi Philippe Meyer Marie-Aude Devynck 《Clinical and experimental pharmacology & physiology》1987,14(3):187-189
1. Plasma renin activity (PRA) and platelet cytosolic free calcium concentration ([Ca2+]i) were simultaneously determined in 18 untreated essential hypertensive subjects and 17 normotensive controls. A significant positive correlation was found between [Ca2+]i and PRA (slope = 42 nmol/l/ng/ml/h) in these 35 subjects. 2. Two determinations more than one week apart in nine subjects confirmed the parallel fluctuations of [Ca2+]i and PRA. A strict sodium restriction produced a progressive PRA elevation associated with a parallel rise in [Ca2+]i in one subject. 3. These results are consistent with the hypothesis that angiotensin II causes a concentration-dependent calcium mobilization. 相似文献